bims-mepmim 2022-07-17 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2022–07–17
twenty-six papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Metabolic requirement for GOT2 in pancreatic cancer depends on environmental context.
Altered Nutrient Uptake Causes Mitochondrial Dysfunction in Senescent CD8+ EMRA T Cells During Type 2 Diabetes.
Elucidating tumour-associated microglia/macrophage diversity along glioblastoma progression and under ACOD1 deficiency.
Tumor cells dictate anti-tumor immune responses by altering pyruvate utilization and succinate signaling in CD8+ T cells.
Obesity Accelerates Age-Associated Defects in Human B Cells Through a Metabolic Reprogramming Induced by the Fatty Acid Palmitate.
Multiomics reveal the central role of pentose phosphate pathway in resident thymic macrophages to cope with efferocytosis-associated stress.
Cancer-Associated Fibroblast-Derived Exosomal miRNA-320a Promotes Macrophage M2 Polarization In Vitro by Regulating PTEN/PI3Kγ Signaling in Pancreatic Cancer.
Butyrate oxidation attenuates the butyrate-induced improvement of insulin sensitivity in myotubes.
Human alveolar macrophages do not rely on glucose metabolism upon activation by lipopolysaccharide.
Systems Immunology Analyses of STAT1 Gain-of-Function Immune Phenotypes Reveal Heterogeneous Response to IL-6 and Broad Immunometabolic Roles for STAT1.
Mitochondrial function in intestinal epithelium homeostasis and modulation in diet-induced obesity.
Nicotinamide Mononucleotide Administration Triggers Macrophages Reprogramming and Alleviates Inflammation During Sepsis Induced by Experimental Peritonitis.
NAD+ salvage governs mitochondrial metabolism invigorating NK cell anti-tumor immunity.
MicroRNA-21 guide and passenger strand regulation of adenylosuccinate lyase-mediated purine metabolism promotes transition to an EGFR-TKI-tolerant persister state.
BAF60a Deficiency in Macrophage Promotes Diet-Induced Obesity and Metabolic Inflammation.
High dietary methionine intake may contribute to the risk of nonalcoholic fatty liver disease by inhibiting hepatic H2S production.
Metastatic Metabolic Plasticity Is Shaped by RNA Methylation Modifications.
GCN2 inhibition sensitizes arginine-deprived hepatocellular carcinoma cells to senolytic treatment.
Bias caused by incomplete metabolite extraction and matrix effect: Evaluation of critical factors for plasma sample preparation prior to metabolomics.
Acetyl-CoA-Carboxylase 1-mediated de novo fatty acid synthesis sustains Lgr5+ intestinal stem cell function.
The role of adipose tissue-derived hydrogen sulfide in inhibiting atherosclerosis.
Proton export upregulates aerobic glycolysis.
An In Vivo Model of Human Macrophages in Metastatic Melanoma.
A ROS-dependent mechanism promotes CDK2 phosphorylation to drive progression through S phase.
Conditioned medium of amniotic fluid-derived stromal cells exerts a bone anabolic effect by enhancing progenitor population and angiogenesis.
Rnd3 Expression is Necessary to Maintain Mitochondrial Homeostasis but Dispensable for Autophagy.

Elife. 2022 Jul 11. pii: e73245. [Epub ahead of print]11

Metabolic requirement for GOT2 in pancreatic cancer depends on environmental context.

Samuel Kerk, Lin Lin, Amy L Myers, Damien J Sutton, Anthony Andren, Peter Sajjakulnukit, Li Zhang, Yaqing Zhang, Jennifer A Jiménez, Barbara S Nelson, Brandon Chen, Anthony Robinson, Galloway Thurston, Samantha B Kemp, Nina G Steele, Megan T Hoffman, Hui-Ju Wen, Daniel Long, Sarah E Ackenhusen, Johanna Ramos, Xiaohua Gao, Zeribe C Nwosu, Stefanie Galban, Christopher J Halbrook, David B Lombard, David R Piwnica-Worms, Haoqiang Ying, Marina Pasca di Magliano, Howard C Crawford, Yatrik M Shah, Costas A Lyssiotis.

  Mitochondrial glutamate-oxaloacetate (GOT2) is part of the malate-aspartate shuttle (MAS), a mechanism by which cells transfer reducing equivalents from the cytosol to the mitochondria. GOT2 is a key component of mutant KRAS (KRAS*)-mediated rewiring of glutamine metabolism in pancreatic ductal adenocarcinoma (PDA). Here, we demonstrate that the loss of GOT2 disturbs redox homeostasis and halts proliferation of PDA cells in vitro. GOT2 knockdown (KD) in PDA cell lines in vitro induced NADH accumulation, decreased Asp and α-ketoglutarate (αKG) production, stalled glycolysis, disrupted the TCA cycle, and impaired proliferation. Oxidizing NADH through chemical or genetic means resolved the redox imbalance induced by GOT2 KD, permitting sustained proliferation. Despite a strong in vitro inhibitory phenotype, loss of GOT2 had no effect on tumor growth in xenograft PDA or autochthonous mouse models. We show that cancer-associated fibroblasts (CAFs), a major component of the pancreatic tumor microenvironment (TME), release the redox active metabolite pyruvate, and culturing GOT2 KD cells in CAF conditioned media (CM) rescued proliferation in vitro. Furthermore, blocking pyruvate import or pyruvate-to-lactate reduction prevented rescue of GOT2 KD in vitro by exogenous pyruvate or CAF CM. However, these interventions failed to sensitize xenografts to GOT2 KD in vivo, demonstrating the remarkable plasticity and differential metabolism deployed by PDA cells in vitro and in vivo. This emphasizes how the environmental context of distinct pre-clinical models impacts both cell-intrinsic metabolic rewiring and metabolic crosstalk with the tumor microenvironment (TME).

Keywords:  biochemistry; cancer biology; chemical biology; human; mouse

DOI:  https://doi.org/10.7554/eLife.73245
Front Aging. 2021 ;2 681428

Altered Nutrient Uptake Causes Mitochondrial Dysfunction in Senescent CD8+ EMRA T Cells During Type 2 Diabetes.

Lauren A Callender, Elizabeth C Carroll, Conor Garrod-Ketchley, Johannes Schroth, Jonas Bystrom, Victoria Berryman, Melanie Pattrick, Desiree Campbell-Richards, Gillian A Hood, Graham A Hitman, Sarah Finer, Sian M Henson.

  Mitochondrial health and cellular metabolism can heavily influence the onset of senescence in T cells. CD8+ EMRA T cells exhibit mitochondrial dysfunction and alterations to oxidative phosphorylation, however, the metabolic properties of senescent CD8+ T cells from people living with type 2 diabetes (T2D) are not known. We show here that mitochondria from T2D CD8+ T cells had a higher oxidative capacity together with increased levels of mitochondrial reactive oxgen species (mtROS), compared to age-matched control cells. While fatty acid uptake was increased, fatty acid oxidation was impaired in T2D CD8+ EMRA T cells, which also showed an accumulation of lipid droplets and decreased AMPK activity. Increasing glucose and fatty acids in healthy CD8+ T cells resulted in increased p-p53 expression and a fragmented mitochondrial morphology, similar to that observed in T2D CD8+ EMRA T cells. The resulting mitochondrial changes are likely to have a profound effect on T cell function. Consequently, a better understanding of these metabolic abnormalities is crucial as metabolic manipulation of these cells may restore correct T cell function and help reduce the impact of T cell dysfunction in T2D.

Keywords:  T cell; ageing; inflammation; metabolism; mitochondria; senescence; type 2 diabetes

DOI:  https://doi.org/10.3389/fragi.2021.681428
Mol Oncol. 2022 Jul 15.

Elucidating tumour-associated microglia/macrophage diversity along glioblastoma progression and under ACOD1 deficiency.

Yolanda Pires-Afonso, Arnaud Muller, Kamil Grzyb, Anaïs Oudin, Yahaya A Yabo, Carole Sousa, Andrea Scafidi, Aurélie Poli, Antonio Cosma, Rashi Halder, Djalil Coowar, Anna Golebiewska, Alexander Skupin, Simone P Niclou, Alessandro Michelucci.

  In glioblastoma (GBM), tumour-associated microglia/macrophages (TAMs) represent the major cell type of the stromal compartment and contribute to tumour immune escape mechanisms. Thus, targeting TAMs is emerging as a promising strategy for immunotherapy. However, TAM heterogeneity and metabolic adaptation along GBM progression represent critical features for the design of effective TAM-targeted therapies. Here, we comprehensively study the cellular and molecular changes of TAMs in the GL261 GBM mouse model, combining single-cell RNA-sequencing with flow cytometry and immunohistological analyses along GBM progression and in the absence of Acod1 (also known as Irg1), a key gene involved in the metabolic reprogramming of macrophages towards an anti-inflammatory phenotype. Similarly to patients, we identify distinct TAM profiles, mainly based on their ontogeny, that reiterate the idea that microglia- and macrophage-like cells show key transcriptional differences and dynamically adapt along GBM stages. Notably, we uncover decreased antigen-presenting cell features and immune reactivity in TAMs along tumour progression that are instead enhanced in Acod1-deficient mice. Overall, our results provide insight into TAM heterogeneity and highlight a novel role for Acod1 in TAM adaptation during GBM progression.

Keywords:  ACOD1/IRG1; Glioblastoma; Heterogeneity; Metabolic reprogramming; Single-cell RNA-sequencing; Tumour-associated microglia/macrophages

DOI:  https://doi.org/10.1002/1878-0261.13287
Cell Metab. 2022 Jul 07. pii: S1550-4131(22)00228-5. [Epub ahead of print]

Tumor cells dictate anti-tumor immune responses by altering pyruvate utilization and succinate signaling in CD8+ T cells.

Ilaria Elia, Jared H Rowe, Sheila Johnson, Shakchhi Joshi, Giulia Notarangelo, Kiran Kurmi, Sarah Weiss, Gordon J Freeman, Arlene H Sharpe, Marcia C Haigis.

  The tumor microenvironment (TME) is a unique metabolic niche that can inhibit T cell metabolism and cytotoxicity. To dissect the metabolic interplay between tumors and T cells, we establish an in vitro system that recapitulates the metabolic niche of the TME and allows us to define cell-specific metabolism. We identify tumor-derived lactate as an inhibitor of CD8+ T cell cytotoxicity, revealing an unexpected metabolic shunt in the TCA cycle. Metabolically fit cytotoxic T cells shunt succinate out of the TCA cycle to promote autocrine signaling via the succinate receptor (SUCNR1). Cytotoxic T cells are reliant on pyruvate carboxylase (PC) to replenish TCA cycle intermediates. By contrast, lactate reduces PC-mediated anaplerosis. The inhibition of pyruvate dehydrogenase (PDH) is sufficient to restore PC activity, succinate secretion, and the activation of SUCNR1. These studies identify PDH as a potential drug target to allow CD8+ T cells to retain cytotoxicity and overcome a lactate-enriched TME.

Keywords:  T cells; cancer metabolism; lactate; pyruvate; succinate; tumor immunity

DOI:  https://doi.org/10.1016/j.cmet.2022.06.008
Front Aging. 2021 ;2 828697

Obesity Accelerates Age-Associated Defects in Human B Cells Through a Metabolic Reprogramming Induced by the Fatty Acid Palmitate.

Daniela Frasca, Maria Romero, Denisse Garcia, Alain Diaz, Bonnie B Blomberg.

  We have measured the secretion of autoimmune antibodies in plasma samples and in culture supernatants of blood-derived B cells from four groups of individuals: young lean (YL), elderly lean (EL), young obese (YO) and elderly obese (EO). We found secretion comparable in YO and EL individuals, suggesting that obesity accelerates age-associated defects in circulating B cells. To define at least one possible molecular pathway involved, we used an in vitro model in which B cells from YL and EL individuals have been stimulated with the Fatty Acid (FA) palmitate, the most common saturated FA in the human body. The rationale to use palmitate is that there is a chronic increase in circulating levels of palmitate, due to increased spontaneous lipolysis occurring during aging and obesity, and this may induce autoimmune B cells. Results herein show that in vitro incubation of B cells from YL and EL individuals with the FA palmitate induces mRNA expression of T-bet, the transcription factor for autoimmune antibodies, as well as secretion of autoimmune IgG antibodies, with B cells from YL individuals looking similar to B cells from EL individuals, confirming our initial hypothesis. The generation of autoimmune B cells in the presence of the FA palmitate was found to be associated with a metabolic reprogramming of B cells from both YL and EL individuals. These results altogether show the critical role of the FA palmitate in inducing human B cell immunosenescence and show for the first time the importance of metabolic pathways in this process.

Keywords:  B cells; aging; autoimmunity; metabolism; obesity

DOI:  https://doi.org/10.3389/fragi.2021.828697
Cell Rep. 2022 Jul 12. pii: S2211-1247(22)00863-4. [Epub ahead of print]40(2): 111065

Multiomics reveal the central role of pentose phosphate pathway in resident thymic macrophages to cope with efferocytosis-associated stress.

Tsung-Lin Tsai, Tyng-An Zhou, Yu-Ting Hsieh, Ju-Chu Wang, Hui-Kuei Cheng, Chen-Hua Huang, Pei-Yuan Tsai, Hsiu-Han Fan, Hsing-Kai Feng, Yu-Chia Huang, Chen-Ching Lin, Chao-Hsiung Lin, Chih-Yu Lin, Ivan L Dzhagalov, Chia-Lin Hsu.

  Tissue-resident macrophages (TRMs) are heterogeneous cell populations found throughout the body. Depending on their location, they perform diverse functions maintaining tissue homeostasis and providing immune surveillance. To survive and function within, TRMs adapt metabolically to the distinct microenvironments. However, little is known about the metabolic signatures of TRMs. The thymus provides a nurturing milieu for developing thymocytes yet efficiently removes those that fail the selection, relying on the resident thymic macrophages (TMφs). This study harnesses multiomics analyses to characterize TMφs and unveils their metabolic features. We find that the pentose phosphate pathway (PPP) is preferentially activated in TMφs, responding to the reduction-oxidation demands associated with the efferocytosis of dying thymocytes. The blockade of PPP in Mφs leads to decreased efferocytosis, which can be rescued by reactive oxygen species (ROS) scavengers. Our study reveals the key role of the PPP in TMφs and underscores the importance of metabolic adaptation in supporting Mφ efferocytosis.

Keywords:  CP: Immunology; CP: Metabolism; efferocytosis; metabolic flexibility; pentose phosphate pathway; reduction-oxidation; thymus; tissue-resident macrophage

DOI:  https://doi.org/10.1016/j.celrep.2022.111065
J Oncol. 2022 ;2022 9514697

Cancer-Associated Fibroblast-Derived Exosomal miRNA-320a Promotes Macrophage M2 Polarization In Vitro by Regulating PTEN/PI3Kγ Signaling in Pancreatic Cancer.

Mingkun Zhao, Aobo Zhuang, Yuan Fang.

Our previous study has indicated that cancer-associated fibroblasts (CAFs) play a crucial role in regulating gemcitabine resistance through transferring exosomal miRNA-106b to cancer cells. Tumor-associated macrophages (TAMs) are recently verified to facilitate gemcitabine resistance. However, the effect of CAFs in regulating TAMs function in pancreatic cancer (PCa) remains unclear. Here, primary CAFs were extracted from tumor tissues of PCa patients, and CAFs-derived exosomes (CAFs-Exo) were acquired and authenticated by transmission electron microscopy, qNano, and western blot analysis. The role of exosomal miRNA-320a in facilitating macrophage M2 polarization was investigated in vitro. We found that CAFs-derived conditioned medium (CM) possessed a higher potential to promote macrophage M2 polarization compared with normal fibroblasts (NFs) or PCa cell-derived CM. Furthermore, CAFs-Exo treatment polarized macrophage to M2 phenotype. miRNA-320a levels were remarkably increased in CAFs-Exo versus NFs-Exo. More important, miRNA-320a could be transferred from CAFs to macrophages through exosomes, and miRNA-320a overexpression in macrophages facilitated its M2 polarization. Functionally, miRNA-320a-overexpressed macrophages facilitated PCa cell proliferation and invasion. CAFs pretreated with miRNA-320a inhibitor reduced miRNA-320a expression in CAFs-Exo and led to decreased M2 macrophage polarization. Finally, we verified that miRNA-320a polarized macrophage to M2 phenotype by regulating PTEN/PI3Kγ signaling. Taken together, the current data demonstrated that CAFs-derived exosomal miRNA-320a facilitated macrophage M2 polarization to accelerate malignant behavior of PCa cells.

DOI: https://doi.org/10.1155/2022/9514697
Biochim Biophys Acta Mol Basis Dis. 2022 Jul 07. pii: S0925-4439(22)00147-8. [Epub ahead of print] 166476

Butyrate oxidation attenuates the butyrate-induced improvement of insulin sensitivity in myotubes.

Melany Rios-Morales, Marcel A Vieira-Lara, Esther Homan, Miriam Langelaar-Makkinje, Albert Gerding, Zhuang Li, Nicolette Huijkman, Patrick C N Rensen, Justina C Wolters, Dirk-Jan Reijngoud, Barbara M Bakker.

  Skeletal muscle insulin resistance is a key pathophysiological process that precedes the development of type 2 diabetes. Whereas an overload of long-chain fatty acids can induce muscle insulin resistance, butyrate, a short-chain fatty acid (SCFA) produced from dietary fibre fermentation, prevents it. This preventive role of butyrate has been attributed to histone deacetylase (HDAC)-mediated transcription regulation and activation of mitochondrial fatty-acid oxidation. Here we address the interplay between butyrate and the long-chain fatty acid palmitate and investigate how transcription, signalling and metabolism are integrated to result in the butyrate-induced skeletal muscle metabolism remodelling. Butyrate enhanced insulin sensitivity in palmitate-treated, insulin-resistant C2C12 cells, as shown by elevated insulin receptor 1 (IRS1) and pAKT protein levels and Slc2a4 (GLUT4) mRNA, which led to a higher glycolytic capacity. Long-chain fatty-acid oxidation capacity and other functional respiration parameters were not affected. Butyrate did upregulate mitochondrial proteins involved in its own oxidation, as well as concentrations of butyrylcarnitine and hydroyxybutyrylcarnitine. By knocking down the gene encoding medium-chain 3-ketoacyl-CoA thiolase (MCKAT, Acaa2), butyrate oxidation was inhibited, which amplified the effects of the SCFA on insulin sensitivity and glycolysis. This response was associated with enhanced HDAC inhibition, based on histone 3 acetylation levels. Butyrate enhances insulin sensitivity and induces glycolysis, without the requirement of upregulated long-chain fatty acid oxidation. Butyrate catabolism functions as an escape valve that attenuates HDAC inhibition. Thus, inhibition of butyrate oxidation indirectly prevents insulin resistance and stimulates glycolytic flux in myotubes treated with butyrate, most likely via an HDAC-dependent mechanism.

Keywords:  Butyrate; Fatty-acid oxidation; Glycolysis; Insulin resistance; Skeletal muscle

DOI:  https://doi.org/10.1016/j.bbadis.2022.166476
Biochim Biophys Acta Mol Basis Dis. 2022 Jul 11. pii: S0925-4439(22)00159-4. [Epub ahead of print] 166488

Human alveolar macrophages do not rely on glucose metabolism upon activation by lipopolysaccharide.

Liza Pereverzeva, Christine C A van Linge, Alex R Schuurman, Augustijn M Klarenbeek, Ivan Ramirez Moral, Natasja A Otto, Hessel Peters Sengers, Joe M Butler, Bauke V Schomakers, Michel van Weeghel, Riekelt H Houtkooper, W Joost Wiersinga, Peter I Bonta, Jouke T Annema, Alex F de Vos, Tom van der Poll.

  Most macrophages generate energy to mount an inflammatory cytokine response by increased glucose metabolism through intracellular glycolysis. Previous studies have suggested that alveolar macrophages (AMs), which reside in a glucose-poor natural environment, are less capable to utilize glycolysis and instead rely on other substrates to fuel oxidative phosphorylation (OXPHOS) for energy supply. At present, it is not known whether AMs are capable to use glucose metabolism to produce cytokines when other metabolic options are blocked. Here, we studied human AMs retrieved by bronchoalveolar lavage from healthy subjects, and examined their glucose metabolism in response to activation by the gram-negative bacterial component lipopolysaccharide (LPS) ex vivo. The immunological and metabolic responses of AMs were compared to those of cultured blood monocyte-derived macrophages (MDMs) from the same subjects. LPS stimulation enhanced cytokine release by both AMs and MDMs, which was associated with increased lactate release by MDMs (reflecting glycolysis), but not by AMs. In agreement, LPS induced higher mRNA expression of multiple glycolytic regulators in MDMs, but not in AMs. Flux analyses of [13C]-glucose revealed no differences in [13C]-incorporation in glucose metabolism intermediates in AMs. Inhibition of OXPHOS by oligomycin strongly reduced LPS-induced cytokine production by AMs, but not by MDMs. Collectively, these results indicate that human AMs, in contrast to MDMs, do not use glucose metabolism during LPS-induced activation and fully rely on OXPHOS for cytokine production.

Keywords:  Alveolar macrophages; Glucose metabolism; Lipopolysaccharide; Monocyte-derived macrophages

DOI:  https://doi.org/10.1016/j.bbadis.2022.166488
Immunohorizons. 2022 Jul 15. 6(7): 447-464

Systems Immunology Analyses of STAT1 Gain-of-Function Immune Phenotypes Reveal Heterogeneous Response to IL-6 and Broad Immunometabolic Roles for STAT1.

Saara Kaviany, Todd Bartkowiak, Daniel E Dulek, Yasmin W Khan, Madeline J Hayes, Samuel G Schaefer, Xiang Ye, Debolanle O Dahunsi, James A Connelly, Jonathan M Irish, Jeffrey C Rathmell.

Patients with STAT1 gain-of-function (GOF) pathogenic variants have enhanced or prolonged STAT1 phosphorylation following cytokine stimulation and exhibit increased yet heterogeneous susceptibility to infections, autoimmunity, and cancer. Although disease phenotypes are diverse and other genetic factors contribute, how STAT1 GOF affects cytokine sensitivity and cell biology remains poorly defined. In this study, we analyzed the immune and immunometabolic profiles of two patients with known pathogenic heterozygous STAT1 GOF mutation variants. A systems immunology approach of peripheral blood cells from these patients revealed major changes in multiple immune cell compartments relative to healthy adult and pediatric donors. Although many phenotypes of STAT1 GOF donors were shared, including increased Th1 cells but decreased class-switched B cells and plasmacytoid dendritic cell populations, others were heterogeneous. Mechanistically, hypersensitivity for cytokine-induced STAT1 phosphorylation in memory T cell populations was particularly evident in response to IL-6 in one STAT1 GOF patient. Immune cell metabolism directly influences cell function, and the STAT1 GOF patients shared an immunometabolic phenotype of heightened glucose transporter 1 (GLUT1) and carnitine palmitoyl transferase 1A (CPT1a) expression across multiple immune cell lineages. Interestingly, the metabolic phenotypes of the pediatric STAT1 GOF donors more closely resembled or exceeded those of healthy adult than healthy age-similar pediatric donors, which had low expression of these metabolic markers. These results define new features of STAT1 GOF patients, including a differential hypersensitivity for IL-6 and a shared increase in markers of metabolism in many immune cell types that suggests a role for STAT1 in metabolic regulation of immunity.

DOI: https://doi.org/10.4049/immunohorizons.2200041
Mol Metab. 2022 Jul 08. pii: S2212-8778(22)00115-6. [Epub ahead of print] 101546

Mitochondrial function in intestinal epithelium homeostasis and modulation in diet-induced obesity.

Thomas Guerbette, Gaëlle Boudry, Annaïg Lan.

   BACKGROUND: Systemic low-grade inflammation observed in diet-induced obesity has been associated with dysbiosis and disturbance of intestinal homeostasis. This latter relies on an efficient epithelial barrier and coordinated intestinal epithelial cell (IEC) renewal that are supported by their mitochondrial function. However, IEC mitochondrial function might be impaired by high fat diet (HFD) consumption, notably through gut-derived metabolite production and fatty acids, that may act as metabolic perturbators of IEC.
SCOPE OF REVIEW: This review presents the current general knowledge on mitochondria, before focusing on IEC mitochondrial function and its role in the control of intestinal homeostasis, and featuring the known effects of nutrients and metabolites, originating from the diet or gut bacterial metabolism, on IEC mitochondrial function. It then summarizes the impact of HFD on mitochondrial function in IEC of both small intestine and colon and discusses the possible link between mitochondrial dysfunction and altered intestinal homeostasis in diet-induced obesity.
MAJOR CONCLUSIONS: HFD consumption provokes a metabolic shift toward fatty acid β-oxidation in the small intestine epithelial cells and impairs colonocyte mitochondrial function, possibly through downstream consequences of excessive fatty acid β-oxidation and/or the presence of deleterious metabolites produced by the gut microbiota. Decreased levels of ATP and concomitant O2 leaks into the intestinal lumen could explain the alterations of intestinal epithelium dynamics, barrier disruption and dysbiosis that contribute to the loss of epithelial homeostasis in diet-induced obesity. However, the effect of HFD on IEC mitochondrial function in the small intestine remains unknown and the precise mechanisms by which HFD induces mitochondrial dysfunction in the colon have not been elucidated so far.

Keywords:  Energy metabolism; High fat diet; Intestine; Mitochondria; Obesity

DOI:  https://doi.org/10.1016/j.molmet.2022.101546
Front Mol Biosci. 2022 ;9 895028

Nicotinamide Mononucleotide Administration Triggers Macrophages Reprogramming and Alleviates Inflammation During Sepsis Induced by Experimental Peritonitis.

Cécile Cros, Marielle Margier, Hélène Cannelle, Julie Charmetant, Nicolas Hulo, Laurent Laganier, Alessia Grozio, Matthias Canault.

  Peritonitis and subsequent sepsis lead to high morbidity and mortality in response to uncontrolled systemic inflammation primarily mediated by macrophages. Nicotinamide adenine dinucleotide (NAD+) is an important regulator of oxidative stress and immunoinflammatory responses. However, the effects of NAD+ replenishment during inflammatory activation are still poorly defined. Hence, we investigated whether the administration of β-nicotinamide mononucleotide (β-NMN), a natural biosynthetic precursor of NAD+, could modulate the macrophage phenotype and thereby ameliorate the dysregulated inflammatory response during sepsis. For this purpose, C57BL6 mice were subjected to the cecal ligation and puncture (CLP) model to provoke sepsis or were injected with thioglycolate to induce sterile peritonitis with recruitment and differentiation of macrophages into the inflamed peritoneal cavity. β-NMN was administered for 4 days after CLP and for 3 days post thioglycolate treatment where peritoneal macrophages were subsequently analyzed. In the CLP model, administration of β-NMN decreased bacterial load in blood and reduced clinical signs of distress and mortality during sepsis. These results were supported by transcriptomic analysis of hearts and lungs 24 h post CLP-induction, which revealed that β-NMN downregulated genes controlling the immuno-inflammatory response and upregulated genes involved in bioenergetic metabolism, mitochondria, and autophagy. In the thioglycolate model, a significant increase in the proportion of CD206 macrophages, marker of anti-inflammatory M2 phenotype, was detected on peritoneal exudate macrophages from β-NMN-administered mice. Transcriptomic signature of these macrophages after bacterial stimulation confirmed that β-NMN administration limited the pro-inflammatory M1 phenotype and induced the expression of specific markers of M2 type macrophages. Furthermore, our data show that β-NMN treatment significantly impacts NAD + metabolism. This shift in the macrophage phenotype and metabolism was accompanied by a reduction in phagolysosome acidification and secretion of inflammatory mediators in macrophages from β-NMN-treated mice suggesting a reduced pro-inflammatory activation. In conclusion, administration of β-NMN prevented clinical deterioration and improved survival during sepsis. These effects relied on shifts in the metabolism of organs that face up an increased energy requirement caused by bacterial infection and in innate immunity response, including reprogramming of macrophages from a highly inflammatory phenotype to an anti-inflammatory/pro-resolving profile.

Keywords:  macrophage; monocyte; nicotinamide adenine dinucleotide; nicotinamide mononucleotide; peritonitis; sepsis

DOI:  https://doi.org/10.3389/fmolb.2022.895028
Hepatology. 2022 Jul 11.

NAD+ salvage governs mitochondrial metabolism invigorating NK cell anti-tumor immunity.

Xiaowei Guo, Siyu Tan, Tixiao Wang, Renhui Sun, Shuangjie Li, Panpan Tian, Mengzhen Li, Yuzhen Wang, Yankun Zhang, Yuchuan Yan, Zhaoru Dong, Lunjie Yan, Xuetian Yue, Zhuanchang Wu, Chunyang Li, Kazuya Yamagata, Lifen Gao, Chunhong Ma, Tao Li, Xiaohong Liang.

BACKGROUND & AIMS: Natural killer (NK) cells are key players in tumor immunosurveillance and metabolic adaption manipulates their fate and functional state. The nicotinamide adenine dinucleotide (NAD+ ) has emerged as a vital factor to link cellular metabolism and signaling transduction. Here, we identified NAD+ metabolism as a central hub to determine the homeostasis and function of NK cells.
APPROACH & RESULTS: NAD+ level was elevated in activated NK cells. NAD+ supplementation not only enhanced cytokine production and cytotoxicity, but also improved the proliferation and viability of NK cells. Intriguingly, the salvage pathway was involved in maintaining NAD+ homeostasis in activated NK cells. Genetic ablation or pharmacological blockade of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD+ salvage pathway, markedly destroyed the viability and function of NK cells. Mechanistically, NAD+ salvage dictated the mitochondrial homeostasis and oxidative phosphorylation activity to support the optimal function of NK cells. However, in human hepatocellular carcinoma (HCC) tissues, NAMPT expression and NAD+ level were significantly downregulated in tumor-infiltrating NK cells (TINKs), which negatively correlated with patient survival. And, lactate accumulation in tumor microenvironment was at least partially responsible for the transcriptional repression of NAMPT in NK cells. Further, deficiency of Nampt in NK cells accelerated the growth of HCC and melanoma. Supplementation of NAD+ precursor, nicotinamide mononucleotide (NMN), significantly improved NK anti-tumor response in both mouse and human cell-derived xenograft.
CONCLUSIONS: These findings reveal NAD+ salvage as an essential factor for NK cell homeostasis and function, suggesting a potential strategy for invigorating NK cell-based immunotherapy.

DOI: https://doi.org/10.1002/hep.32658
Cancer Gene Ther. 2022 Jul 15.

MicroRNA-21 guide and passenger strand regulation of adenylosuccinate lyase-mediated purine metabolism promotes transition to an EGFR-TKI-tolerant persister state.

Wen Cai Zhang, Nicholas Skiados, Fareesa Aftab, Cerena Moreno, Luis Silva, Paul Joshua Anthony Corbilla, John M Asara, Aaron N Hata, Frank J Slack.

In EGFR-mutant lung cancer, drug-tolerant persister cells (DTPCs) show prolonged survival when receiving EGFR tyrosine kinase inhibitor (TKI) treatments. They are a likely source of drug resistance, but little is known about how these cells tolerate drugs. Ribonucleic acids (RNAs) molecules control cell growth and stress responses. Nucleic acid metabolism provides metabolites, such as purines, supporting RNA synthesis and downstream functions. Recently, noncoding RNAs (ncRNAs), such as microRNAs (miRNAs), have received attention due to their capacity to repress gene expression via inhibitory binding to downstream messenger RNAs (mRNAs). Here, our study links miRNA expression to purine metabolism and drug tolerance. MiR-21-5p (guide strand) is a commonly upregulated miRNA in disease states, including cancer and drug resistance. However, the expression and function of miR-21-3p (passenger strand) are not well understood. We found that upregulation of miR-21-5p and miR-21-3p tune purine metabolism leading to increased drug tolerance. Metabolomics data demonstrated that purine metabolism was the top pathway in the DTPCs compared with the parental cells. The changes in purine metabolites in the DTPCs were partially rescued by targeting miR-21. Analysis of protein levels in the DTPCs showed that reduced expression of adenylosuccinate lyase (ADSL) was reversed after the miR-21 knockdown. ADSL is an essential enzyme in the de novo purine biosynthesis pathway by converting succino-5-aminoimidazole-4-carboxamide riboside (succino-AICAR or SAICAR) to AICAR (or acadesine) as well as adenylosuccinate to adenosine monophosphate (AMP). In the DTPCs, miR-21-5p and miR-21-3p repress ADSL expression. The levels of top decreased metabolite in the DTPCs, AICAR was reversed when miR-21 was blocked. AICAR induced oxidative stress, evidenced by increased reactive oxygen species (ROS) and reduced expression of nuclear factor erythroid-2-related factor 2 (NRF2). Concurrently, miR-21 knockdown induced ROS generation. Therapeutically, a combination of AICAR and osimertinib increased ROS levels and decreased osimertinib-induced NRF2 expression. In a MIR21 knockout mouse model, MIR21 loss-of-function led to increased purine metabolites but reduced ROS scavenging capacity in lung tissues in physiological conditions. Our data has established a link between ncRNAs, purine metabolism, and the redox imbalance pathway. This discovery will increase knowledge of the complexity of the regulatory RNA network and potentially enable novel therapeutic options for drug-resistant patients.

DOI: https://doi.org/10.1038/s41417-022-00504-y
Diabetes. 2022 Jul 13. pii: db220114. [Epub ahead of print]

BAF60a Deficiency in Macrophage Promotes Diet-Induced Obesity and Metabolic Inflammation.

Qin Kong, Jiahuan Zou, Ziyin Zhang, Ran Pan, Zhe Yu Zhang, Shuang Han, Yanyong Xu, Yue Gao, Zhuo-Xian Meng.

Adipose tissue macrophage (ATM) has been shown to play a key role in the pathogenesis of obesity-associated adipose tissue inflammation and metabolic diseases. However, the upstream factors that integrate the environmental signals to control ATM activation and adipose inflammation in obesity remain elusive. Here, we identify BAF60a, a subunit of the SWI/SNF chromatin remodeling complexes, as the central checkpoint regulator of obesity-induced ATM activation, adipose tissue inflammation and systemic metabolic impairment. BAF60a expression was robustly downregulated in the adipose tissue stromal vascular fractions (SVFs) in type 2 diabetic mice. Myeloid-specific BAF60a ablation (BaMKO) promotes ATM pro-inflammatory activation, exacerbating diet-induced obesity, insulin resistance and metabolic dysfunction. Conversely, myeloid-specific overexpression of BAF60a in mice attenuates macrophage pro-inflammatory activation. Mechanistically, transcriptome and chromatin landscape analyses demonstrate that BAF60a inactivation triggers the expression of pro-inflammatory gene program through chromatin remodeling. Moreover, motif analysis of ATAC-Seq and CUT&Tag-Seq data identifies the transcription factor Atf3 that physically interacts with BAF60a to suppress the pro-inflammatory gene expression, thereby controlling ATM activation and metabolic inflammation in obesity. Consistently, myeloid-specific Atf3 deficiency also promotes the pro-inflammatory activation of macrophage. Together, this work uncovers BAF60a/Atf3 axis as the key regulator in obesity-associated ATM activation, adipose tissue inflammation and metabolic diseases.

DOI: https://doi.org/10.2337/db22-0114
Food Res Int. 2022 Aug;pii: S0963-9969(22)00565-8. [Epub ahead of print]158 111507

High dietary methionine intake may contribute to the risk of nonalcoholic fatty liver disease by inhibiting hepatic H2S production.

Yuhui Yang, Manman Lu, Yuncong Xu, Jing Qian, Guowei Le, Yanli Xie.

  Methionine, an essential sulfur-containing amino acid, is associated with hepatic lipid accumulation; however, the underlying mechanism is unknown. This study aimed to investigate the effects of different dietary methionine levels on hepatic lipid accumulation in mice and clarify the possible mechanisms involved. The Institute of Cancer Research (ICR) mice were fed a normal diet (ND, 0.86% methionine), high-methionine diet (HMD, 2.58% methionine), or methionine-restricted diet (MRD, 0.17% methionine) for 11 consecutive weeks. Our results showed that HMD increased the liver weight and liver index, plasma and hepatic lipid profiles, and hepatic fatty infiltration area and perirenal fat volume. In addition, HMD promoted lipid synthesis, inhibited lipid catabolism and glycolysis metabolism, reduced the activities of mitochondrial respiratory chain enzyme complexes (Ⅰ and Ⅴ) and adenosine triphosphate (ATP) production, and elevated oxidative stress and inflammation in the liver. Moreover, HMD inhibited homocysteine metabolism and significantly decreased the expression and activity of cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST), thereby reducing endogenous H2S production in the liver. Interestingly, MRD reversed these adverse effects, and promoted endogenous H2S production. In conclusion, inhibition of hepatic H2S production may be the mechanism behind an increased risk of nonalcoholic fatty liver disease (NAFLD) associated with high dietary methionine intake. Therefore, it is necessary to reduce methionine intake in the daily diet to prevent NAFLD and maintain good physical health.

Keywords:  Excess methionine; Fatty liver; Hepatic lipid accumulation; Hydrogen sulfide; Methionine; Methionine restriction; Oxidative stress

DOI:  https://doi.org/10.1016/j.foodres.2022.111507
Cancer Discov. 2022 Jul 15. OF1

Metastatic Metabolic Plasticity Is Shaped by RNA Methylation Modifications.

The m5c and f5c RNA modifications support mitochondrial mRNA translation promoting metastasis.

DOI: https://doi.org/10.1158/2159-8290.CD-RW2022-126
Cell Metab. 2022 Jul 08. pii: S1550-4131(22)00230-3. [Epub ahead of print]

GCN2 inhibition sensitizes arginine-deprived hepatocellular carcinoma cells to senolytic treatment.

Rindert Missiaen, Nicole M Anderson, Laura C Kim, Bailey Nance, Michelle Burrows, Nicolas Skuli, Madeleine Carens, Romain Riscal, An Steensels, Fuming Li, M Celeste Simon.

  Hepatocellular carcinoma (HCC) is a typically fatal malignancy exhibiting genetic heterogeneity and limited therapy responses. We demonstrate here that HCCs consistently repress urea cycle gene expression and thereby become auxotrophic for exogenous arginine. Surprisingly, arginine import is uniquely dependent on the cationic amino acid transporter SLC7A1, whose inhibition slows HCC cell growth in vitro and in vivo. Moreover, arginine deprivation engages an integrated stress response that promotes HCC cell-cycle arrest and quiescence, dependent on the general control nonderepressible 2 (GCN2) kinase. Inhibiting GCN2 in arginine-deprived HCC cells promotes a senescent phenotype instead, rendering these cells vulnerable to senolytic compounds. Preclinical models confirm that combined dietary arginine deprivation, GCN2 inhibition, and senotherapy promote HCC cell apoptosis and tumor regression. These data suggest novel strategies to treat human liver cancers through targeting SLC7A1 and/or a combination of arginine restriction, inhibition of GCN2, and senolytic agents.

Keywords:  GCN2; arginine; hepatocellular carcinoma; senescence; urea cycle

DOI:  https://doi.org/10.1016/j.cmet.2022.06.010
J Pharm Biomed Anal. 2022 Jul 06. pii: S0731-7085(22)00351-X. [Epub ahead of print]219 114930

Bias caused by incomplete metabolite extraction and matrix effect: Evaluation of critical factors for plasma sample preparation prior to metabolomics.

Hsiao-Wei Liao, Yu-Wen Cheng, Sung-Chun Tang, Ching-Hua Kuo.

  Metabolomics is an omics strategy to study the metabolite alteration in the biological system. Unbiased observation of the metabolite level is essential for targeted metabolite quantification and untargeted metabolic profiling. State-of-the-art instruments and versatile tools have been developed for accurate observation of metabolic alterations in various studies. Several analytical pitfalls, such as sample overloading and signal-saturation-induced bias, have been revealed and addressed. In this study, we proposed incomplete-metabolite-extraction-caused bias is also an important issue that results in biased observation when performing metabolomics. In the demonstration example, numerous metabolites exhibited no significant difference between extracted plasma samples with different plasma contents, which is attributed to incomplete-metabolite-extraction-caused bias and matrix effect. Matrix effect is a well-known factor that result in biased observation, it can be reduced by sample dilution and compensated by using stable isotope labelled internal standards. The detection of metabolite signals in the following consecutive extractions provided further evidence of incomplete metabolite extraction. The completeness of metabolite extraction is crucial for unbiased observation of metabolic profile changes. To address this issue, we optimized the extraction time and methanol volume to reduce the incomplete-metabolite-extraction-caused bias and evaluated the metabolite signals in consecutive extractions. Methanol extraction performed with a plasma-to-methanol ratio of 1:14 resulted in metabolite responses of less than 18.1 % in the second extractions observed by metabolomic profiling. Finally, the optimized sample preparation procedure and untargeted profiling platform were applied to detect metabolite alterations associated with patients with cerebrovascular diseases and several features with significant difference were successfully identified. This study revealed and evaluated the bias caused by incomplete metabolite extraction and matrix effect in the commonly used methanol extraction method for human plasma sample preparation for metabolomics. We anticipate the proposed metabolite extraction evaluation method could benefit more clinical and biological metabolomics studies.

Keywords:  Cerebrovascular diseases; Incomplete metabolite extraction; Liquid chromatography electrospray ionization-mass spectrometry; Metabolomics; Plasma

DOI:  https://doi.org/10.1016/j.jpba.2022.114930
Nat Commun. 2022 Jul 09. 13(1): 3998

Acetyl-CoA-Carboxylase 1-mediated de novo fatty acid synthesis sustains Lgr5+ intestinal stem cell function.

Shuting Li, Chia-Wen Lu, Elia C Diem, Wang Li, Melanie Guderian, Marc Lindenberg, Friederike Kruse, Manuela Buettner, Stefan Floess, Markus R Winny, Robert Geffers, Hans-Hermann Richnow, Wolf-Rainer Abraham, Guntram A Grassl, Matthias Lochner.

Basic processes of the fatty acid metabolism have an important impact on the function of intestinal epithelial cells (IEC). However, while the role of cellular fatty acid oxidation is well appreciated, it is not clear how de novo fatty acid synthesis (FAS) influences the biology of IECs. We report here that interfering with de novo FAS by deletion of the enzyme Acetyl-CoA-Carboxylase (ACC)1 in IECs results in the loss of epithelial crypt structures and a specific decline in Lgr5+ intestinal epithelial stem cells (ISC). Mechanistically, ACC1-mediated de novo FAS supports the formation of intestinal organoids and the differentiation of complex crypt structures by sustaining the nuclear accumulation of PPARδ/β-catenin in ISCs. The dependency of ISCs on cellular de novo FAS is tuned by the availability of environmental lipids, as an excess delivery of external fatty acids is sufficient to rescue the defect in crypt formation. Finally, inhibition of ACC1 reduces the formation of tumors in colitis-associated colon cancer, together highlighting the importance of cellular lipogenesis for sustaining ISC function and providing a potential perspective to colon cancer therapy.

DOI: https://doi.org/10.1038/s41467-022-31725-2
Nitric Oxide. 2022 Jul 12. pii: S1089-8603(22)00071-4. [Epub ahead of print]

The role of adipose tissue-derived hydrogen sulfide in inhibiting atherosclerosis.

Zhen Tian, Nian-Hua Deng, Zhi-Xiang Zhou, Zhong Ren, Wen-Hao Xiong, Zhi-Sheng Jiang.

  Hydrogen sulfide (H2S) is the third gaseous signaling molecule discovered in the body after NO and CO and plays an important organismal protective role in various diseases. Within adipose tissue, related catalytic enzymes (cystathionine-β-synthetase, cystathionine-γ-lyase, and 3-mercaptopyruvate transsulfuration enzyme) can produce and release endogenous H2S. Atherosclerosis (As) is a pathological change in arterial vessels that is closely related to abnormal glucose and lipid metabolism and a chronic inflammatory response. Previous studies have shown that H2S can act on the cardiovascular system, exerting effects such as improving disorders of glycolipid metabolism, alleviating insulin resistance, protecting the function of vascular endothelial cells, inhibiting vascular smooth muscle cell proliferation and migration, regulating vascular tone, inhibiting the inflammatory response, and antagonizing the occurrence and development of As.

Keywords:  Adipose tissue; Atherosclerosis; Hydrogen sulfide; PVAT

DOI:  https://doi.org/10.1016/j.niox.2022.07.001
BMC Biol. 2022 Jul 15. 20(1): 163

Proton export upregulates aerobic glycolysis.

Shonagh Russell, Liping Xu, Yoonseok Kam, Dominique Abrahams, Bryce Ordway, Alex S Lopez, Marilyn M Bui, Joseph Johnson, Tamir Epstein, Epifanio Ruiz, Mark C Lloyd, Pawel Swietach, Daniel Verduzco, Jonathan Wojtkowiak, Robert J Gillies.

   INTRODUCTION: Aggressive cancers commonly ferment glucose to lactic acid at high rates, even in the presence of oxygen. This is known as aerobic glycolysis, or the "Warburg Effect." It is widely assumed that this is a consequence of the upregulation of glycolytic enzymes. Oncogenic drivers can increase the expression of most proteins in the glycolytic pathway, including the terminal step of exporting H+ equivalents from the cytoplasm. Proton exporters maintain an alkaline cytoplasmic pH, which can enhance all glycolytic enzyme activities, even in the absence of oncogene-related expression changes. Based on this observation, we hypothesized that increased uptake and fermentative metabolism of glucose could be driven by the expulsion of H+ equivalents from the cell.
RESULTS: To test this hypothesis, we stably transfected lowly glycolytic MCF-7, U2-OS, and glycolytic HEK293 cells to express proton-exporting systems: either PMA1 (plasma membrane ATPase 1, a yeast H+-ATPase) or CA-IX (carbonic anhydrase 9). The expression of either exporter in vitro enhanced aerobic glycolysis as measured by glucose consumption, lactate production, and extracellular acidification rate. This resulted in an increased intracellular pH, and metabolomic analyses indicated that this was associated with an increased flux of all glycolytic enzymes upstream of pyruvate kinase. These cells also demonstrated increased migratory and invasive phenotypes in vitro, and these were recapitulated in vivo by more aggressive behavior, whereby the acid-producing cells formed higher-grade tumors with higher rates of metastases. Neutralizing tumor acidity with oral buffers reduced the metastatic burden.
CONCLUSIONS: Therefore, cancer cells which increase export of H+ equivalents subsequently increase intracellular alkalization, even without oncogenic driver mutations, and this is sufficient to alter cancer metabolism towards an upregulation of aerobic glycolysis, a Warburg phenotype. Overall, we have shown that the traditional understanding of cancer cells favoring glycolysis and the subsequent extracellular acidification is not always linear. Cells which can, independent of metabolism, acidify through proton exporter activity can sufficiently drive their metabolism towards glycolysis providing an important fitness advantage for survival.

Keywords:  CA-IX; Cancer; Glycolysis; Metastasis; PMA1; Proton; Warburg; pH

DOI:  https://doi.org/10.1186/s12915-022-01340-0
J Immunol. 2022 Jul 11. pii: ji2101109. [Epub ahead of print]

An In Vivo Model of Human Macrophages in Metastatic Melanoma.

Valentin Voillet, Trisha R Berger, Kelly M McKenna, Kelly G Paulson, Wei Hong Tan, Kimberly S Smythe, Daniel S Hunter, William J Valente, Stephanie Weaver, Jean S Campbell, Teresa S Kim, David R Byrd, Jason H Bielas, Robert H Pierce, Aude G Chapuis, Raphaël Gottardo, Anthony Rongvaux.

Despite recent therapeutic progress, advanced melanoma remains lethal for many patients. The composition of the immune tumor microenvironment (TME) has decisive impacts on therapy response and disease outcome, and high-dimensional analyses of patient samples reveal the heterogeneity of the immune TME. Macrophages infiltrate TMEs and generally associate with tumor progression, but the underlying mechanisms are incompletely understood. Because experimental systems are needed to elucidate the functional properties of these cells, we developed a humanized mouse model reconstituted with human immune cells and human melanoma. We used two strains of recipient mice, supporting or not supporting the development of human myeloid cells. We found that human myeloid cells favored metastatic spread of the primary tumor, thereby recapitulating the cancer-supportive role of macrophages. We next analyzed the transcriptome of human immune cells infiltrating tumors versus other tissues. This analysis identified a cluster of myeloid cells present in the TME, but not in other tissues, which do not correspond to canonical M2 cells. The transcriptome of these cells is characterized by high expression of glycolytic enzymes and multiple chemokines and by low expression of gene sets associated with inflammation and adaptive immunity. Compared with humanized mouse results, we found transcriptionally similar myeloid cells in patient-derived samples of melanoma and other cancer types. The humanized mouse model described here thus complements patient sample analyses, enabling further elucidation of fundamental principles in melanoma biology beyond M1/M2 macrophage polarization. The model can also support the development and evaluation of candidate antitumor therapies.

DOI: https://doi.org/10.4049/jimmunol.2101109
Dev Cell. 2022 Jul 05. pii: S1534-5807(22)00448-8. [Epub ahead of print]

A ROS-dependent mechanism promotes CDK2 phosphorylation to drive progression through S phase.

Dilyana Georgieva Kirova, Kristyna Judasova, Julia Vorhauser, Thomas Zerjatke, Jacky Kieran Leung, Ingmar Glauche, Jörg Mansfeld.

  Reactive oxygen species (ROS) at the right concentration promote cell proliferation in cell culture, stem cells, and model organisms. However, the mystery of how ROS signaling is coordinated with cell cycle progression and integrated into the cell cycle control machinery on the molecular level remains unsolved. Here, we report increasing levels of mitochondrial ROS during the cell cycle in human cell lines that target cyclin-dependent kinase 2 (CDK2). Chemical and metabolic interferences with ROS production decrease T-loop phosphorylation on CDK2 and so impede its full activation and thus its efficient DNA replication. ROS regulate CDK2 activity through the oxidation of a conserved cysteine residue near the T-loop, which prevents the binding of the T-loop phosphatase KAP. Together, our data reveal how mitochondrial metabolism is coupled with DNA replication and cell cycle progression via ROS, thereby demonstrating how KAP activity toward CDKs can be cell cycle regulated.

Keywords:  CDK2; DNA replication; KAP; T-loop phosphorylation; cell cycle; cyclin-dependent kinase; metabolism; mitochondria; proliferation; reactive oxygen species

DOI:  https://doi.org/10.1016/j.devcel.2022.06.008
J Tissue Eng Regen Med. 2022 Jul 12.

Conditioned medium of amniotic fluid-derived stromal cells exerts a bone anabolic effect by enhancing progenitor population and angiogenesis.

Min-Kyoung Song, Hyun Jin Sun, Sun Wook Cho.

  A cell-free approach utilizing the paracrine effects of mesenchymal stromal cells is receiving attention in regenerative medicine. In the present study, we evaluated the effects of a conditioned medium of amniotic fluid-derived stromal cells (AFSC-CM) on bone metabolism. In mice, intraperitoneal injections of AFSC-CM increased bone mass and enhanced bone turnover. The precursor populations of myeloid and mesenchymal lineages, as well as endothelial cells in bone marrow, were also augmented by AFSC-CM administration. In an in vitro culture experiment, AFSC-CM increased osteoclast differentiation of bone marrow-derived macrophages, but had no significant effect on the osteogenic differentiation of preosteoblasts. However, AFSC-CM administration dramatically accelerated the migration and tube formation of endothelial cells, and a cytokine array showed that AFSC-CM contained many angiogenic factors. These results indicate that AFSC-CM exerts a bone anabolic effect by changing the bone marrow microenvironment, including angiogenesis and precursor expansion. Therefore, ameliorating marrow angiogenesis is a potential therapeutic strategy for bone regeneration, for which AFSCs can be a good cellular source.

Keywords:  amniotic fluid derived stromal cells (AFSC); angiogenesis; bone; bone marrow microenvironment; conditioned medium

DOI:  https://doi.org/10.1002/term.3340
Front Cell Dev Biol. 2022 ;10 834561

Rnd3 Expression is Necessary to Maintain Mitochondrial Homeostasis but Dispensable for Autophagy.

Cristina Cueto-Ureña, Enric Mocholí, Josep Escrivá-Fernández, Susana González-Granero, Sabina Sánchez-Hernández, Amalia Solana-Orts, Begoña Ballester-Lurbe, Karim Benabdellah, Rosa M Guasch, José Manuel García-Verdugo, Francisco Martín, Paul J Coffer, Ignacio Pérez-Roger, Enric Poch.

  Autophagy is a highly conserved process that mediates the targeting and degradation of intracellular components to lysosomes, contributing to the maintenance of cellular homeostasis and to obtaining energy, which ensures viability under stress conditions. Therefore, autophagy defects are common to different neurodegenerative disorders. Rnd3 belongs to the family of Rho GTPases, involved in the regulation of actin cytoskeleton dynamics and important in the modulation of cellular processes such as migration and proliferation. Murine models have shown that Rnd3 is relevant for the correct development and function of the Central Nervous System and lack of its expression produces several motor alterations and neural development impairment. However, little is known about the molecular events through which Rnd3 produces these phenotypes. Interestingly we have observed that Rnd3 deficiency correlates with the appearance of autophagy impairment profiles and irregular mitochondria. In this work, we have explored the impact of Rnd3 loss of expression in mitochondrial function and autophagy, using a Rnd3 KO CRISPR cell model. Rnd3 deficient cells show no alterations in autophagy and mitochondria turnover is not impaired. However, Rnd3 KO cells have an altered mitochondria oxidative metabolism, resembling the effect caused by oxidative stress. In fact, lack of Rnd3 expression makes these cells strictly dependent on glycolysis to obtain energy. Altogether, our results demonstrate that Rnd3 is relevant to maintain mitochondria function, suggesting a possible relationship with neurodegenerative diseases.

Keywords:  OXPHOS (oxidative phosphorylation); Rnd3/RhoE; autophagy; mitochondrial dysfunction (MtD); neurodisorders

DOI:  https://doi.org/10.3389/fcell.2022.834561