bims-midhyp 2023-10-29 papers

bims-midhyp

Biomed News

on Mitochondrial dysfunction and hypoxia

Issue of 2023‒10‒29
eighteen papers selected by
Alia Abukiwan, University of Heidelberg

Mitochondrial complex I ROS production and redox signaling in hypoxia.
Hypoxia and HIF-1α Regulate the Activity and Expression of Na,K-ATPase Subunits in H9c2 Cardiomyoblasts.
Endoplasmic Reticulum Stress Promotes the Expression of TNF-α in THP-1 Cells by Mechanisms Involving ROS/CHOP/HIF-1α and MAPK/NF-κB Pathways.
Endothelial Cell Dysfunction and Hypoxia as Potential Mediators of Pain in Fabry Disease: A Human-Murine Translational Approach.
Acute Kidney Injury by Ischemia/Reperfusion and Extracellular Vesicles.
NDRG1 promotes endothelial dysfunction and hypoxia-induced pulmonary hypertension by targeting TAF15.
MicroRNA-specific therapeutic targets and biomarkers of apoptosis following myocardial ischemia-reperfusion injury.
MDM2 Regulation of HIF Signaling Causes Microvascular Dysfunction in Hypertrophic Cardiomyopathy.
Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency.
Transcriptomics and metabolomics study in mouse kidney of the molecular mechanism underlying energy metabolism response to hypoxic stress in highland areas.
Role of prostanoids, nitric oxide and endothelin pathways in pulmonary hypertension due to COPD.
Mitochondrial translocase TOMM22 is overexpressed in pancreatic cancer and promotes aggressive growth by modulating mitochondrial protein import and function.
HSP70 inhibitor amplifies the bFGF‑induced release of IL‑6 in osteoblasts.
Metabolic switches during development and regeneration.
The interplay between metabolic stochasticity and cAMP-CRP regulation in single E. coli cells.
Microcirculation and Mitochondria: The Critical Unit.
Adaptive responses of neuronal cells to chronic endoplasmic reticulum (ER) stress.
Cell phenotypes can be predicted from propensities of protein conformations.

Redox Biol. 2023 Oct 16. pii: S2213-2317(23)00327-0. [Epub ahead of print]67 102926

Mitochondrial complex I ROS production and redox signaling in hypoxia.

Chidozie N Okoye, Shon A Koren, Andrew P Wojtovich.

  Mitochondria are a main source of cellular energy. Oxidative phosphorylation (OXPHOS) is the major process of aerobic respiration. Enzyme complexes of the electron transport chain (ETC) pump protons to generate a protonmotive force (Δp) that drives OXPHOS. Complex I is an electron entry point into the ETC. Complex I oxidizes nicotinamide adenine dinucleotide (NADH) and transfers electrons to ubiquinone in a reaction coupled with proton pumping. Complex I also produces reactive oxygen species (ROS) under various conditions. The enzymatic activities of complex I can be regulated by metabolic conditions and serves as a regulatory node of the ETC. Complex I ROS plays diverse roles in cell metabolism ranging from physiologic to pathologic conditions. Progress in our understanding indicates that ROS release from complex I serves important signaling functions. Increasing evidence suggests that complex I ROS is important in signaling a mismatch in energy production and demand. In this article, we review the role of ROS from complex I in sensing acute hypoxia.

Keywords:  Acute hypoxia; Mitochondrial complex I; Oxygen sensing; ROS signaling

DOI:  https://doi.org/10.1016/j.redox.2023.102926
Curr Issues Mol Biol. 2023 Oct 12. 45(10): 8277-8288

Hypoxia and HIF-1α Regulate the Activity and Expression of Na,K-ATPase Subunits in H9c2 Cardiomyoblasts.

Beyza Gurler, Gizem Gencay, Emel Baloglu.

  The optimal function of the Na,K-ATPase (NKA) pump is essential for the heart. In ischemic heart disease, NKA activity decreases due to the decreased expression of the pump subunits. Here, we tested whether the hypoxia-inducible transcription factor (HIF-1α), the key signaling molecule regulating the adaptation of cells to hypoxia, is involved in controlling the expression and cellular dynamics of α1- and β1-NKA isoforms and of NKA activity in in-vitro hypoxic H9c2 cardiomyoblasts. HIF-1α was silenced through adenoviral infection, and cells were kept in normoxia (19% O2) or hypoxia (1% O2) for 24 h. We investigated the mRNA and protein expression of α1-, β1-NKA using RT-qPCR and Western blot in whole-cell lysates, cell membranes, and cytoplasmic fractions after labeling the cell surface with NHS-SS-biotin and immunoprecipitation. NKA activity and intracellular ATP levels were also measured. We found that in hypoxia, silencing HIF-1α prevented the decreased mRNA expression of α1-NKA but not of β1-NKA. Hypoxia decreased the plasma membrane expression of α1-NKA and β1- NKA compared to normoxic cells. In hypoxic cells, HIF-1α silencing prevented this effect by inhibiting the internalization of α1-NKA. Total protein expression was not affected. The decreased activity of NKA in hypoxic cells was fully prevented by silencing HIF-1α independent of cellular ATP levels. This study is the first to show that in hypoxic H9c2 cardiomyoblasts, HIF-1α controls the internalization and membrane insertion of α1-NKA subunit and of NKA activity. The mechanism behind this regulation needs further investigation.

Keywords:  H9c2 cardiomyoblasts; HIF-1α; Na,K-ATPase; hypoxia; ischemic heart disease; ouabain

DOI:  https://doi.org/10.3390/cimb45100522
Int J Mol Sci. 2023 Oct 14. pii: 15186. [Epub ahead of print]24(20):

Endoplasmic Reticulum Stress Promotes the Expression of TNF-α in THP-1 Cells by Mechanisms Involving ROS/CHOP/HIF-1α and MAPK/NF-κB Pathways.

Nadeem Akhter, Ajit Wilson, Hossein Arefanian, Reeby Thomas, Shihab Kochumon, Fatema Al-Rashed, Mohamed Abu-Farha, Ashraf Al-Madhoun, Fahd Al-Mulla, Rasheed Ahmad, Sardar Sindhu.

  Obesity and metabolic syndrome involve chronic low-grade inflammation called metabolic inflammation as well as metabolic derangements from increased endotoxin and free fatty acids. It is debated whether the endoplasmic reticulum (ER) stress in monocytic cells can contribute to amplify metabolic inflammation; if so, by which mechanism(s). To test this, metabolic stress was induced in THP-1 cells and primary human monocytes by treatments with lipopolysaccharide (LPS), palmitic acid (PA), or oleic acid (OA), in the presence or absence of the ER stressor thapsigargin (TG). Gene expression of tumor necrosis factor (TNF)-α and markers of ER/oxidative stress were determined by qRT-PCR, TNF-α protein by ELISA, reactive oxygen species (ROS) by DCFH-DA assay, hypoxia-inducible factor 1-alpha (HIF-1α), p38, extracellular signal-regulated kinase (ERK)-1,2, and nuclear factor kappa B (NF-κB) phosphorylation by immunoblotting, and insulin sensitivity by glucose-uptake assay. Regarding clinical analyses, adipose TNF-α was assessed using qRT-PCR/IHC and plasma TNF-α, high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and oxidized low-density lipoprotein (OX-LDL) via ELISA. We found that the cooperative interaction between metabolic and ER stresses promoted TNF-α, ROS, CCAAT-enhancer-binding protein homologous protein (CHOP), activating transcription factor 6 (ATF6), superoxide dismutase 2 (SOD2), and nuclear factor erythroid 2-related factor 2 (NRF2) expression (p ≤ 0.0183),. However, glucose uptake was not impaired. TNF-α amplification was dependent on HIF-1α stabilization and p38 MAPK/p65 NF-κB phosphorylation, while the MAPK/NF-κB pathway inhibitors and antioxidants/ROS scavengers such as curcumin, allopurinol, and apocynin attenuated the TNF-α production (p ≤ 0.05). Individuals with obesity displayed increased adipose TNF-α gene/protein expression as well as elevated plasma levels of TNF-α, CRP, MDA, and OX-LDL (p ≤ 0.05). Our findings support a metabolic-ER stress cooperativity model, favoring inflammation by triggering TNF-α production via the ROS/CHOP/HIF-1α and MAPK/NF-κB dependent mechanisms. This study also highlights the therapeutic potential of antioxidants in inflammatory conditions involving metabolic/ER stresses.

Keywords:  CHOP; ER stress; HIF-1α; MAPK/NF-κB; ROS; TNF-α; inflammation; metabolic stress; metabolic syndrome; obesity

DOI:  https://doi.org/10.3390/ijms242015186
Int J Mol Sci. 2023 Oct 21. pii: 15422. [Epub ahead of print]24(20):

Endothelial Cell Dysfunction and Hypoxia as Potential Mediators of Pain in Fabry Disease: A Human-Murine Translational Approach.

Katharina Klug, Marlene Spitzel, Clara Hans, Alexandra Klein, Nicole Michelle Schottmann, Christoph Erbacher, Nurcan Üçeyler.

  Fabry disease (FD) is caused by α-galactosidase A (AGAL) enzyme deficiency, leading to globotriaosylceramide accumulation (Gb3) in several cell types. Pain is one of the pathophysiologically incompletely understood symptoms in FD patients. Previous data suggest an involvement of hypoxia and mitochondriopathy in FD pain development at dorsal root ganglion (DRG) level. Using immunofluorescence and quantitative real-time polymerase chain reaction (qRT PCR), we investigated patient-derived endothelial cells (EC) and DRG tissue of the GLA knockout (KO) mouse model of FD. We address the question of whether hypoxia and mitochondriopathy contribute to FD pain pathophysiology. In EC of FD patients (P1 with pain and, P2 without pain), we found dysregulated protein expression of hypoxia-inducible factors (HIF) 1a and HIF2 compared to the control EC (p < 0.01). The protein expression of the HIF downstream target vascular endothelial growth factor A (VEGFA, p < 0.01) was reduced and tube formation was hampered in the P1 EC compared to the healthy EC (p < 0.05). Tube formation ability was rescued by applying transforming growth factor beta (TGFβ) inhibitor SB-431542. Additionally, we found dysregulated mitochondrial fusion/fission characteristics in the P1 and P2 EC (p < 0.01) and depolarized mitochondrial membrane potential in P2 compared to control EC (p < 0.05). Complementary to human data, we found upregulated hypoxia-associated genes in the DRG of old GLA KO mice compared to WT DRG (p < 0.01). At protein level, nuclear HIF1a was higher in the DRG neurons of old GLA KO mice compared to WT mice (p < 0.01). Further, the HIF1a downstream target CA9 was upregulated in the DRG of old GLA KO mice compared to WT DRG (p < 0.01). Similar to human EC, we found a reduction in the vascular characteristics in GLA KO DRG compared to WT (p < 0.05). We demonstrate increased hypoxia, impaired vascular properties, and mitochondrial dysfunction in human FD EC and complementarily at the GLA KO mouse DRG level. Our data support the hypothesis that hypoxia and mitochondriopathy in FD EC and GLA KO DRG may contribute to FD pain development.

Keywords:  Fabry disease; GLA KO mouse model; blood vessels; dorsal root ganglion; endothelial cells; hypoxia; iPSC; mitochondriopathy; vasculopathy

DOI:  https://doi.org/10.3390/ijms242015422
Int J Mol Sci. 2023 Oct 18. pii: 15312. [Epub ahead of print]24(20):

Acute Kidney Injury by Ischemia/Reperfusion and Extracellular Vesicles.

Mikkel Ørnfeldt Nørgård, Per Svenningsen.

  Acute kidney injury (AKI) is often caused by ischemia-reperfusion injury (IRI). IRI significantly affects kidney metabolism, which elicits pro-inflammatory responses and kidney injury. The ischemia/reperfusion of the kidney is associated with transient high mitochondrial-derived reactive oxygen species (ROS) production rates. Excessive mitochondrial-derived ROS damages cellular components and, together with other pathogenic mechanisms, elicits a range of acute injury mechanisms that impair kidney function. Mitochondrial-derived ROS production also stimulates epithelial cell secretion of extracellular vesicles (EVs) containing RNAs, lipids, and proteins, suggesting that EVs are involved in AKI pathogenesis. This literature review focuses on how EV secretion is stimulated during ischemia/reperfusion and how cell-specific EVs and their molecular cargo may modify the IRI process. Moreover, critical pitfalls in the analysis of kidney epithelial-derived EVs are described. In particular, we will focus on how the release of kidney epithelial EVs is affected during tissue analyses and how this may confound data on cell-to-cell signaling. By increasing awareness of methodological pitfalls in renal EV research, the risk of false negatives can be mitigated. This will improve future EV data interpretation regarding EVs contribution to AKI pathogenesis and their potential as biomarkers or treatments for AKI.

Keywords:  extracellular vesicle release; ischemia; metabolism; mitochondria; reperfusion

DOI:  https://doi.org/10.3390/ijms242015312
Precis Clin Med. 2023 Dec;6(4): pbad024

NDRG1 promotes endothelial dysfunction and hypoxia-induced pulmonary hypertension by targeting TAF15.

Chengwei Li, Junzhu Lv, Gulinuer Wumaier, Yu Zhao, Liang Dong, Yuzhen Zeng, Ning Zhu, Xiujuan Zhang, Jing Wang, Jingwen Xia, Shengqing Li.

  Background: Pulmonary hypertension (PH) represents a threatening pathophysiologic state that can be induced by chronic hypoxia and is characterized by extensive vascular remodeling. However, the mechanism underlying hypoxia-induced vascular remodeling is not fully elucidated.Methods and Results: By using quantitative polymerase chain reactions, western blotting, and immunohistochemistry, we demonstrate that the expression of N-myc downstream regulated gene-1 (NDRG1) is markedly increased in hypoxia-stimulated endothelial cells in a time-dependent manner as well as in human and rat endothelium lesions. To determine the role of NDRG1 in endothelial dysfunction, we performed loss-of-function studies using NDRG1 short hairpin RNAs and NDRG1 over-expression plasmids. In vitro, silencing NDRG1 attenuated proliferation, migration, and tube formation of human pulmonary artery endothelial cells (HPAECs) under hypoxia, while NDRG1 over-expression promoted these behaviors of HPAECs. Mechanistically, NDRG1 can directly interact with TATA-box binding protein associated factor 15 (TAF15) and promote its nuclear localization. Knockdown of TAF15 abrogated the effect of NDRG1 on the proliferation, migration and tube formation capacity of HPAECs. Bioinformatics studies found that TAF15 was involved in regulating PI3K-Akt, p53, and hypoxia-inducible factor 1 (HIF-1) signaling pathways, which have been proved to be PH-related pathways. In addition, vascular remodeling and right ventricular hypertrophy induced by hypoxia were markedly alleviated in NDRG1 knock-down rats compared with their wild-type littermates.
Conclusions: Taken together, our results indicate that hypoxia-induced upregulation of NDRG1 contributes to endothelial dysfunction through targeting TAF15, which ultimately contributes to the development of hypoxia-induced PH.

Keywords:  N-myc downstream regulated gene-1; TATA-box binding protein associated factor 15; endothelial dysfunction; hypoxia-induced pulmonary hypertension; vascular remodeling

DOI:  https://doi.org/10.1093/pcmedi/pbad024
Mol Cell Biochem. 2023 Oct 25.

MicroRNA-specific therapeutic targets and biomarkers of apoptosis following myocardial ischemia-reperfusion injury.

Teng Ge, Bo Ning, Yongqing Wu, Xiaolin Chen, Hongfei Qi, Haifang Wang, Mingjun Zhao.

  MicroRNAs are single-stranded non-coding RNAs that participate in post-transcriptional regulation of gene expression, it is involved in the regulation of apoptosis after myocardial ischemia-reperfusion injury. For example, the alteration of mitochondrial structure is facilitated by MicroRNA-1 through the regulation of apoptosis-related proteins, such as Bax and Bcl-2, thereby mitigating cardiomyocyte apoptosis. MicroRNA-21 not only modulates the expression of NF-κB to suppress inflammatory signals but also activates the PI3K/AKT pathway to mitigate ischemia-reperfusion injury. Overexpression of MicroRNA-133 attenuates reactive oxygen species (ROS) production and suppressed the oxidative stress response, thereby mitigating cellular apoptosis. MicroRNA-139 modulates the extrinsic death signal of Fas, while MicroRNA-145 regulates endoplasmic reticulum calcium overload, both of which exert regulatory effects on cardiomyocyte apoptosis. Therefore, the article categorizes the molecular mechanisms based on the three classical pathways and multiple signaling pathways of apoptosis. It summarizes the targets and pathways of MicroRNA therapy for ischemia-reperfusion injury and analyzes future research directions.

Keywords:  Apoptosis; Endoplasmic reticulum; Exogenous death signals; MicroRNA; Mitochondria; Myocardial ischemia–reperfusion injury; Targeted therapy

DOI:  https://doi.org/10.1007/s11010-023-04876-z
Circulation. 2023 Oct 27.

MDM2 Regulation of HIF Signaling Causes Microvascular Dysfunction in Hypertrophic Cardiomyopathy.

Puneeth Shridhar, Michael S Glennon, Soumojit Pal, Christina J Waldron, Ethan J Chetkof, Payel Basak, Nicolas G Clavere, Dipanjan Banerjee, Sebastien Gingras, Jason R Becker.

  BACKGROUND: Microvasculature dysfunction is a common finding in pathologic remodeling of the heart and is thought to play an important role in the pathogenesis of hypertrophic cardiomyopathy (HCM), a disease caused by sarcomere gene mutations. We hypothesized that microvascular dysfunction in HCM was secondary to abnormal microvascular growth and could occur independent of ventricular hypertrophy.METHODS: We used multimodality imaging methods to track the temporality of microvascular dysfunction in HCM mouse models harboring mutations in the sarcomere genes Mybpc3(cardiac myosin binding protein 3) or Myh6 (myosin heavy chain 6). We performed complementary molecular methods to assess protein quantity, interactions, and post-translational modifications to identify mechanisms regulating this response. We manipulated select molecular pathways in vivo using both genetic and pharmacological methods to validate these mechanisms.
RESULTS: We found that microvascular dysfunction in our HCM models occurred secondary to reduced myocardial capillary growth during the early postnatal time period and could occur before the onset of myocardial hypertrophy. We discovered that the E3 ubiquitin protein ligase MDM2 (murine double minute 2) dynamically regulates the protein stability of both HIF1α (hypoxia-inducible factor 1 alpha) and HIF2α (hypoxia-inducible factor 2 alpha)/EPAS1 (endothelial PAS domain protein 1) through canonical and noncanonical mechanisms. The resulting HIF imbalance leads to reduced proangiogenic gene expression during a key period of myocardial capillary growth. Reducing MDM2 protein levels by genetic or pharmacological methods normalized HIF protein levels and prevented the development of microvascular dysfunction in both HCM models.
CONCLUSIONS: Our results show that sarcomere mutations induce cardiomyocyte MDM2 signaling during the earliest stages of disease, and this leads to long-term changes in the myocardial microenvironment.

Keywords:  capillaries; cardiomyopathy, hypertrophic; myosin heavy chains; proteasome endopeptidase complex

DOI:  https://doi.org/10.1161/CIRCULATIONAHA.123.064332
Redox Biol. 2023 Oct 17. pii: S2213-2317(23)00333-6. [Epub ahead of print]67 102932

Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency.

Gerardo G Piroli, Allison M Manuel, Richard S McCain, Holland H Smith, Oliver Ozohanics, Sara Mellid, J Hunter Cox, William E Cotham, Michael D Walla, Alberto Cascón, Attila Ambrus, Norma Frizzell.

  The NDUFS4 knockout (KO) mouse phenotype resembles the human Complex I deficiency Leigh Syndrome. The irreversible succination of protein thiols by fumarate is increased in select regions of the NDUFS4 KO brain affected by neurodegeneration. We report that dihydrolipoyllysine-residue succinyltransferase (DLST), a component of the α-ketoglutarate dehydrogenase complex (KGDHC) of the tricarboxylic acid (TCA) cycle, is succinated in the affected regions of the NDUFS4 KO brain. Succination of DLST reduced KGDHC activity in the brainstem (BS) and olfactory bulb (OB) of KO mice. The defective production of KGDHC derived succinyl-CoA resulted in decreased mitochondrial substrate level phosphorylation (SLP), further aggravating the existing oxidative phosphorylation (OXPHOS) ATP deficit. Protein succinylation, an acylation modification that requires succinyl-CoA, was reduced in the KO mice. Modeling succination of a cysteine in the spatial vicinity of the DLST active site or introduction of succinomimetic mutations recapitulates these metabolic deficits. Our data demonstrate that the biochemical deficit extends beyond impaired Complex I assembly and OXPHOS deficiency, functionally impairing select components of the TCA cycle to drive metabolic perturbations in affected neurons.

Keywords:  Alpha-ketoglutarate dehydrogenase; Complex I; Fumarate; Leigh syndrome; Protein succination; Substrate level phosphorylation

DOI:  https://doi.org/10.1016/j.redox.2023.102932
Exp Ther Med. 2023 Nov;26(5): 533

Transcriptomics and metabolomics study in mouse kidney of the molecular mechanism underlying energy metabolism response to hypoxic stress in highland areas.

Yujie Gao, Qifu Long, Hui Yang, Ying Hu, Yuzhen Xu, Chaoqun Tang, Cunlin Gu, Sheng Yong.

  Exposure to hypoxia disrupts energy metabolism and induces inflammation. However, the pathways and mechanisms underlying energy metabolism disorders caused by hypoxic conditions remain unclear. In the present study, a hypoxic animal model was created and transcriptomic and non-targeted metabolomics techniques were applied to further investigate the pathways and mechanisms of hypoxia exposure that disrupt energy metabolism. Transcriptome results showed that 3,007 genes were significantly differentially expressed under hypoxic exposure, and Gene Ontology annotation analysis and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis showed that the differentially expressed genes (DEGs) were mainly involved in energy metabolism and were significantly enriched in the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) pathway. The DEGs IDH3A, SUCLA2, and MDH2 in the TCA cycle and the DEGs NDUFA3, NDUFS7, UQCRC1, CYC1 and UQCRFS1 in the OXPHOS pathway were validated using mRNA and protein expression, and the results showed downregulation. The results of non-targeted metabolomics showed that 365 significant differential metabolites were identified under plateau hypoxia stress. KEGG enrichment analysis showed that the differential metabolites were mainly enriched in metabolic processes, such as energy, nucleotide and amino acid metabolism. Hypoxia exposure disrupted the TCA cycle and reduced the synthesis of amino acids and nucleotides by decreasing the concentration of cis-aconitate, α-ketoglutarate, NADH, NADPH and that of most amino acids, purines, and pyrimidines. Bioinformatics analysis was used to identify inflammatory genes related to hypoxia exposure and some of them were selected for verification. It was shown that the mRNA and protein expression levels of IL1B, IL12B, S100A8 and S100A9 in kidney tissues were upregulated under hypoxic exposure. The results suggest that hypoxia exposure inhibits the TCA cycle and the OXPHOS signalling pathway by inhibiting IDH3A, SUCLA2, MDH2, NDUFFA3, NDUFS7, UQCRC1, CYC1 and UQCRFS1, thereby suppressing energy metabolism, inducing amino acid and nucleotide deficiency and promoting inflammation, ultimately leading to kidney damage.

Keywords:  hypoxia; inflammation; kidney; metabolomics; mitochondrial dysfunction; oxidative phosphorylation; transcriptomics; tricarboxylic acid cycle

DOI:  https://doi.org/10.3892/etm.2023.12232
Front Med (Lausanne). 2023 ;10 1275684

Role of prostanoids, nitric oxide and endothelin pathways in pulmonary hypertension due to COPD.

Abdullah A Alqarni, Abdulelah M Aldhahir, Sara A Alghamdi, Jaber S Alqahtani, Rayan A Siraj, Hassan Alwafi, Abdulkareem A AlGarni, Mansour S Majrshi, Saad M Alshehri, Linhua Pang.

  Pulmonary hypertension (PH) due to chronic obstructive pulmonary disease (COPD) is classified as Group 3 PH, with no current proven targeted therapies. Studies suggest that cigarette smoke, the most risk factor for COPD can cause vascular remodelling and eventually PH as a result of dysfunction and proliferation of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs). In addition, hypoxia is a known driver of pulmonary vascular remodelling in COPD, and it is also thought that the presence of hypoxia in patients with COPD may further exaggerate cigarette smoke-induced vascular remodelling; however, the underlying cause is not fully understood. Three main pathways (prostanoids, nitric oxide and endothelin) are currently used as a therapeutic target for the treatment of patients with different groups of PH. However, drugs targeting these three pathways are not approved for patients with COPD-associated PH due to lack of evidence. Thus, this review aims to shed light on the role of impaired prostanoids, nitric oxide and endothelin pathways in cigarette smoke- and hypoxia-induced pulmonary vascular remodelling and also discusses the potential of using these pathways as therapeutic target for patients with PH secondary to COPD.

Keywords:  COPD; COPD-associated pulmonary hypertension; endothelin; nitric oxide; prostanoid; pulmonary hypertension; pulmonary hypertension in COPD; type 3 pulmonary hypertension

DOI:  https://doi.org/10.3389/fmed.2023.1275684
Mol Cancer Res. 2023 Oct 25.

Mitochondrial translocase TOMM22 is overexpressed in pancreatic cancer and promotes aggressive growth by modulating mitochondrial protein import and function.

Mary Oluwadamilola Haastrup, Kunwar Somesh Vikramdeo, Shashi Anand, Mohammad Aslam Khan, James Elliot Carter, Seema Singh, Ajay Pratap Singh, Santanu Dasgupta.

Pancreatic cancer has the worst prognosis among all cancers underscoring the need for improved management strategies. Dysregulated mitochondrial function is a common feature in several malignancies, including pancreatic cancer. Although mitochondria have their own genome, most mitochondrial proteins are nuclear-encoded and imported by a multi-subunit translocase of the outer mitochondrial membrane (TOMM). TOMM22 is the central receptor of the TOMM complex and plays a role in complex assembly. Pathobiological roles of TOMM subunits remain largely unexplored. Here we report that TOMM22 protein/mRNA is overexpressed in pancreatic cancer and inversely correlated with disease outcomes. TOMM22 silencing decreased, while its forced overexpression promoted the growth and malignant potential of the pancreatic cancer cells. Increased import of several mitochondrial proteins, including those associated with mitochondrial respiration, was observed upon TOMM22 overexpression which was associated with increased RCI activity, NAD+/NADH ratio, oxygen consumption rate, membrane potential, and ATP production. Inhibition of RCI activity decreased ATP levels and suppressed pancreatic cancer cell growth and malignant behavior confirming that increased TOMM22 expression mediated the phenotypic changes via its modulation of mitochondrial protein import and functions. Altogether, these results suggest that TOMM22 overexpression plays a significant role in pancreatic cancer pathobiology by altering mitochondrial protein import and functions. Implications: TOMM22 bears potential for early diagnostic/prognostic biomarker development and therapeutic targeting for better management of pancreatic cancer patients.

DOI: https://doi.org/10.1158/1541-7786.MCR-23-0138
Mol Med Rep. 2023 Dec;pii: 230. [Epub ahead of print]28(6):

HSP70 inhibitor amplifies the bFGF‑induced release of IL‑6 in osteoblasts.

Gen Kuroyanagi, Tomoyuki Hioki, Rie Matsushima-Nishiwaki, Osamu Kozawa, Haruhiko Tokuda.

  Heat shock protein 70 (HSP70) functions as an ATP‑dependent molecular chaperone under stress and is involved in protein homeostasis, folding and degradation. HSP70 inhibitors amplify TGF‑β‑stimulated VEGF synthesis in the mouse osteoblastic MC3T3‑E1 cell line. Basic fibroblast growth factor (bFGF) stimulates IL‑6 release via p38 MAPK in MC3T3‑E1 osteoblast‑like cells. In the present study, the effects of HSP70 on the bFGF‑stimulated release of IL‑6 was evaluated using MC3T3‑E1 osteoblast‑like cells. IL‑6 release and mRNA expression levels were analyzed using ELISA and reverse transcription‑quantitative PCR, respectively. Phosphorylation of p38 MAPK and HSP70 was assessed using western blotting. HSP70 inhibitor VER‑155008 significantly increased the bFGF‑stimulated release of IL‑6 in both MC3T3‑E1 osteoblastic cells and normal human osteoblasts. Furthermore, VER‑155008 significantly enhanced the mRNA expression levels of IL‑6 stimulated by bFGF. Western blotting demonstrated a significant increase in the bFGF‑stimulated phosphorylation of p38 MAPK in VER‑155008‑treated MC3T3‑E1 cells. A significant increase in the bFGF‑stimulated phosphorylation of p38 MAPK was also demonstrated in MC3T3‑E1 cells treated with YM‑08, another HSP70 inhibitor. VER‑155008 or YM‑08 did not significantly affect the expression of HSP70 with or without bFGF stimulation. Finally, the specific p38 MAPK inhibitor SB203580 markedly suppressed the enhancing effects of VER‑155008 on bFGF‑stimulated release of IL‑6. Taken together, these results indicated that HSP70 inhibitor amplified bFGF‑stimulated release of IL‑6 through p38 MAPK activation in the osteoblastic MC3T3‑E1 cell line.

Keywords:  IL‑6; basic fibroblast growth factor; heat shock protein 70; heat shock protein 70 inhibitor; osteoblast; p38 MAP kinase

DOI:  https://doi.org/10.3892/mmr.2023.13117
Development. 2023 Oct 15. pii: dev202008. [Epub ahead of print]150(20):

Metabolic switches during development and regeneration.

Ahmed I Mahmoud.

  Metabolic switches are a crucial hallmark of cellular development and regeneration. In response to changes in their environment or physiological state, cells undergo coordinated metabolic switching that is necessary to execute biosynthetic demands of growth and repair. In this Review, we discuss how metabolic switches represent an evolutionarily conserved mechanism that orchestrates tissue development and regeneration, allowing cells to adapt rapidly to changing conditions during development and postnatally. We further explore the dynamic interplay between metabolism and how it is not only an output, but also a driver of cellular functions, such as cell proliferation and maturation. Finally, we underscore the epigenetic and cellular mechanisms by which metabolic switches mediate biosynthetic needs during development and regeneration, and how understanding these mechanisms is important for advancing our knowledge of tissue development and devising new strategies to promote tissue regeneration.

Keywords:  Embryonic development; Epigenetics; Metabolic switch; Postnatal development; Regeneration; Reprogramming; Stem cells

DOI:  https://doi.org/10.1242/dev.202008
Cell Rep. 2023 Oct 20. pii: S2211-1247(23)01296-2. [Epub ahead of print]42(10): 113284

The interplay between metabolic stochasticity and cAMP-CRP regulation in single E. coli cells.

Martijn Wehrens, Laurens H J Krah, Benjamin D Towbin, Rutger Hermsen, Sander J Tans.

  The inherent stochasticity of metabolism raises a critical question for understanding homeostasis: are cellular processes regulated in response to internal fluctuations? Here, we show that, in E. coli cells under constant external conditions, catabolic enzyme expression continuously responds to metabolic fluctuations. The underlying regulatory feedback is enabled by the cyclic AMP (cAMP) and cAMP receptor protein (CRP) system, which controls catabolic enzyme expression based on metabolite concentrations. Using single-cell microscopy, genetic constructs in which this feedback is disabled, and mathematical modeling, we show how fluctuations circulate through the metabolic and genetic network at sub-cell-cycle timescales. Modeling identifies four noise propagation modes, including one specific to CRP regulation. Together, these modes correctly predict noise circulation at perturbed cAMP levels. The cAMP-CRP system may thus have evolved to control internal metabolic fluctuations in addition to external growth conditions. We conjecture that second messengers may more broadly function to achieve cellular homeostasis.

Keywords:  CP: Cell biology; CP: Microbiology; CRP; Escherichia coli; cAMP-CRP; gene expression; heterogeneity; noise; regulation; single cell; stochasticity; time lapse microscopy

DOI:  https://doi.org/10.1016/j.celrep.2023.113284
J Clin Med. 2023 Oct 11. pii: 6453. [Epub ahead of print]12(20):

Microcirculation and Mitochondria: The Critical Unit.

Guangjian Wang, Hui Lian, Hongmin Zhang, Xiaoting Wang.

  Critical illness is often accompanied by a hemodynamic imbalance between macrocirculation and microcirculation, as well as mitochondrial dysfunction. Microcirculatory disorders lead to abnormalities in the supply of oxygen to tissue cells, while mitochondrial dysfunction leads to abnormal energy metabolism and impaired tissue oxygen utilization, making these conditions important pathogenic factors of critical illness. At the same time, there is a close relationship between the microcirculation and mitochondria. We introduce here the concept of a "critical unit", with two core components: microcirculation, which mainly comprises the microvascular network and endothelial cells, especially the endothelial glycocalyx; and mitochondria, which are mainly involved in energy metabolism but perform other non-negligible functions. This review also introduces several techniques and devices that can be utilized for the real-time synchronous monitoring of the microcirculation and mitochondria, and thus critical unit monitoring. Finally, we put forward the concepts and strategies of critical unit-guided treatment.

Keywords:  critical illness; critical unit; microcirculation; mitochondria; monitoring technique; treatment strategy

DOI:  https://doi.org/10.3390/jcm12206453
Redox Biol. 2023 Oct 20. pii: S2213-2317(23)00344-0. [Epub ahead of print]67 102943

Adaptive responses of neuronal cells to chronic endoplasmic reticulum (ER) stress.

Thu Nguyen Minh Pham, Natarajan Perumal, Caroline Manicam, Marion Basoglu, Stefan Eimer, Dominik C Fuhrmann, Claus U Pietrzik, Albrecht M Clement, Hagen Körschgen, Jana Schepers, Christian Behl.

  Accumulation of misfolded proteins or perturbation of calcium homeostasis leads to endoplasmic reticulum (ER) stress and is linked to the pathogenesis of neurodegenerative diseases. Hence, understanding the ability of neuronal cells to cope with chronic ER stress is of fundamental interest. Interestingly, several brain areas uphold functions that enable them to resist challenges associated with neurodegeneration. Here, we established novel clonal mouse hippocampal (HT22) cell lines that are resistant to prolonged (chronic) ER stress induced by thapsigargin (TgR) or tunicamycin (TmR) as in vitro models to study the adaption to ER stress. Morphologically, we observed a significant increase in vesicular und autophagosomal structures in both resistant lines and 'giant lysosomes', especially striking in TgR cells. While autophagic activity increased under ER stress, lysosomal function appeared slightly impaired; in both cell lines, we observed enhanced ER-phagy. However, proteomic analyses revealed that various protein clusters and signaling pathways were differentially regulated in TgR versus TmR cells in response to chronic ER stress. Additionally, bioenergetic analyses in both resistant cell lines showed a shift toward aerobic glycolysis ('Warburg effect') and a defective complex I of the oxidative phosphorylation (OXPHOS) machinery. Furthermore, ER stress-resistant cells differentially activated the unfolded protein response (UPR) comprising IRE1α and ATF6 pathways. These findings display the wide portfolio of adaptive responses of neuronal cells to chronic ER stress. ER stress-resistant neuronal cells could be the basis to uncover molecular modulators of adaptation, resistance, and neuroprotection as potential pharmacological targets for preventing neurodegeneration.

Keywords:  Aerobic glycolysis; ER stress resistance; ER-Phagy; Giant lysosomes; Neuroprotection; Warburg effect

DOI:  https://doi.org/10.1016/j.redox.2023.102943
Curr Opin Struct Biol. 2023 Oct 21. pii: S0959-440X(23)00196-3. [Epub ahead of print]83 102722

Cell phenotypes can be predicted from propensities of protein conformations.

Ruth Nussinov, Yonglan Liu, Wengang Zhang, Hyunbum Jang.

  Proteins exist as dynamic conformational ensembles. Here we suggest that the propensities of the conformations can be predictors of cell function. The conformational states that the molecules preferentially visit can be viewed as phenotypic determinants, and their mutations work by altering the relative propensities, thus the cell phenotype. Our examples include (i) inactive state variants harboring cancer driver mutations that present active state-like conformational features, as in K-Ras4BG12V compared to other K-Ras4BG12X mutations; (ii) mutants of the same protein presenting vastly different phenotypic and clinical profiles: cancer and neurodevelopmental disorders; (iii) alterations in the occupancies of the conformational (sub)states influencing enzyme reactivity. Thus, protein conformational propensities can determine cell fate. They can also suggest the allosteric drugs efficiency.

Keywords:  Cancer; Cell fate; Conformational ensembles; Neurodevelopmental disorders; Occupancy; RASopathies

DOI:  https://doi.org/10.1016/j.sbi.2023.102722