bims-midhyp 2023-11-19 papers

bims-midhyp

Biomed News

on Mitochondrial dysfunction and hypoxia

Issue of 2023–11–19
twelve papers selected by
Alia Ablieh, Universität Heidelberg

GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress.
Do the Effects of Krebs Cycle Intermediates on Oxygen-Dependent Processes in Hypoxia Mediated by the Nitric Oxide System Have Reciprocal or Competitive Relationships?
The essential chaperone DNAJC17 activates HSP70 to coordinate RNA splicing and G2-M progression.
Sleep, Hypoxia, and Survival in Group 1 Pulmonary Arterial Hypertension: What to Do?
Targeting mitochondrial shape: at the heart of cardioprotection.
Transcriptional co-activators: emerging roles in signaling pathways and potential therapeutic targets for diseases.
Female sex protects against renal edema, but not lung edema, in mice with partial deletion of the endothelial barrier regulator Tie2 compared to male sex.
Interrogating the Role of miR-125b and Its 3'isomiRs in Protection against Hypoxia.
Endothelial cell dysfunction in cardiac disease: driver or consequence?
PAX3-FOXO1 dictates myogenic reprogramming and rhabdomyosarcoma identity in endothelial progenitors.
The human mitochondrial mRNA structurome reveals mechanisms of gene expression.
Centromere innovations within a mouse species.

bioRxiv. 2023 Oct 26. pii: 2023.10.26.564170. [Epub ahead of print]

GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress.

Paramesha Bugga, Janet R Manning, Bellina A S Mushala, Michael W Stoner, John Sembrat, Iain Scott.

Cardiomyocyte apoptosis and cardiac fibrosis are the leading causes of mortality in patients with ischemic heart disease. As such, these processes represent potential therapeutic targets to treat heart failure resulting from ischemic insult. We previously demonstrated that the mitochondrial acetyltransferase protein GCN5L1 regulates cardiomyocyte cytoprotective signaling in ischemia- reperfusion injury in vivo and hypoxia-reoxygenation injury in vitro . The current study investigated the mechanism underlying GCN5L1-mediated regulation of the Akt/mTORC2 cardioprotective signaling pathway. Rictor protein levels in cardiac tissues from human ischemic heart disease patients were significantly decreased relative to non-ischemic controls. Rictor protein levels were similarly decreased in cardiac AC16 cells following hypoxic stress, while mRNA levels remained unchanged. The reduction in Rictor protein levels after hypoxia was enhanced by the knockdown of GCN5L1, and was blocked by GCN5L1 overexpression. These findings correlated with changes in Rictor lysine acetylation, which were mediated by GCN5L1 acetyltransferase activity. Rictor degradation was regulated by proteasomal activity, which was antagonized by increased Rictor acetylation. Finally, we found that GCN5L1 knockdown restricted cytoprotective Akt signaling, in conjunction with decreased mTOR abundance and activity. In summary, these studies suggest that GCN5L1 promotes cardioprotective Akt/mTORC2 signaling by maintaining Rictor protein levels through enhanced lysine acetylation.

DOI: https://doi.org/10.1101/2023.10.26.564170
Cell Physiol Biochem. 2023 Nov 15. 57(6): 426-451

Do the Effects of Krebs Cycle Intermediates on Oxygen-Dependent Processes in Hypoxia Mediated by the Nitric Oxide System Have Reciprocal or Competitive Relationships?

Natalia Kurhaluk, Oleksandr Lukash, Halina Tkaczenko.

   BACKGROUND/AIMS: Currently, it is proven that the cellular metabolism of nitric oxide is necessary to maintain optimal health and adaptation of the organism to the impact of various environmental factors. The aim of this work was to reveal the biological role of nitric oxide, its metabolic changes, and its mechanism of action in tissues under hypoxia, as well as the possibility of tissue metabolism correction through NO-dependent systems under the influence of Krebs cycle intermediates.
METHODS: A systematic assessment of the effect of succinate (SC, 50 mg/kg b.w.) and α-ketoglutarate (KGL, 50 mg/kg b.w.) in the regulation of oxygendependent processes in rats (mitochondrial oxidative phosphorylation, microsomal oxidation, intensity of lipid peroxidation processes, and the state of the antioxidant defense system) depending on functional changes in nitric oxide production during hypoxia was evaluated. The state of the nitric oxide system was estimated spectrophotometrically by determination of the concentration of its stable nitrite anion metabolite (NO2 -). The levels of catecholamines were estimated from the content of epinephrine and norepinephrine using the differentially fluorescent method. The activity of cytochrome P450-dependent aminopyrine-N-demethylase was determined with the Nash reagent.
RESULTS: Tissue hypoxia and metabolic disorders caused by this condition through changes in the content of catecholamines (epinephrine, norepinephrine, dopamine, DOPA) as well as the cholinesterase-related system (acetylcholine content and acetylcholinesterase activity) were the studied experimental parameters under acute hypoxia (AH, 7% O2 in N2, 30 min). The activation of lipid peroxidation and oxidatively modified proteins and an increase in the epinephrine content in AH are associated with an increased role of SC and a decrease in KGL as substrates of oxidation in mitochondria. A more pronounced effect of exogenous KGL, compared to SC, on the content of nitrite anion as a stable metabolite of nitric oxide in the liver under acute hypoxia against the background of a decrease in the intensity of lipid peroxidation processes was revealed. The activation of SC-dependent mitochondrial oxidative processes caused by AH was found to decrease in animals after an intermittent hypoxia training (IHT) course. IHT (7% O2 in N2, 15-min, 5 times daily, 14 days) prevented the activation of oxidative stress in tissues and blood after the AH impact and increased the efficiency of energy-related reactions in the functioning of hepatic mitochondria through increased oxidation of KGL.
CONCLUSION: The studied effects of adaptation are mediated by an increase in the role of NO-dependent mechanisms, as assessed by changes in the pool of nitrates, nitrites, carbamides, and total polyamines.

Keywords:  Succinate; α-ketoglutarate; Mitochondrial oxidative phosphorylation; Microsomal oxidation; Intermittent hypoxia training; Catecholamines

DOI:  https://doi.org/10.33594/000000669
bioRxiv. 2023 Oct 26. pii: 2023.10.25.564066. [Epub ahead of print]

The essential chaperone DNAJC17 activates HSP70 to coordinate RNA splicing and G2-M progression.

David V Allegakoen, Kristen Kwong, Jacqueline Morales, Trever G Bivona, Amit J Sabnis.

Molecular chaperones including the heat-shock protein 70-kilodalton (HSP70) family and the J-domain containing protein (JDP) co-chaperones maintain homeostatic balance in eukaryotic cells through regulation of the proteome. The expansive JDP family helps direct specific HSP70 functions, and yet loss of single JDP-encoding genes is widely tolerated by mammalian cells, suggesting a high degree of redundancy. By contrast, essential JDPs might carry out HSP70-independent functions or fill cell-context dependent, highly specialized roles within the proteostasis network. Using a genetic screen of JDPs in human cancer cell lines, we found the RNA recognition motif (RRM) containing DNAJC17 to be pan-essential and investigated the contribution of its structural domains to biochemical and cellular function. We found that the RRM exerts an auto-inhibitory effect on the ability of DNAJC17 to allosterically activate ATP hydrolysis by HSP70. The J-domain, but neither the RRM nor a distal C-terminal alpha helix are required to rescue cell viability after loss of endogenous DNAJC17 . Knockdown of DNAJC17 leads to relatively few conserved changes in the abundance of individual mRNAs, but instead deranges gene expression through exon skipping, primarily of genes involved in cell cycle progression. Concordant with cell viability experiments, the C-terminal portions of DNAJC17 are dispensable for restoring splicing and G2-M progression. Overall, our findings identify essential cellular JDPs and suggest that diversification in JDP structure extends the HSP70-JDP system to control divergent processes such as RNA splicing. Future investigations into the structural basis for auto-inhibition of the DNAJC17 J-domain and the molecular regulation of splicing by these components may provide insights on how conserved biochemical mechanisms can be programmed to fill unique, non-redundant cellular roles and broaden the scope of the proteostasis network.

DOI: https://doi.org/10.1101/2023.10.25.564066
J Am Coll Cardiol. 2023 Nov 21. pii: S0735-1097(23)07737-9. [Epub ahead of print]82(21): 2006-2008

Sleep, Hypoxia, and Survival in Group 1 Pulmonary Arterial Hypertension: What to Do?

Shahrokh Javaheri, Virend K Somers.



Keywords:  connective tissue disease-associated pulmonary arterial hypertension; obstructive sleep apnea; pulmonary arterial hypertension; pulmonary hypertension; right ventricular dysfunction; sleep-related hypoxia

DOI:  https://doi.org/10.1016/j.jacc.2023.10.005
Basic Res Cardiol. 2023 Nov 13. 118(1): 49

Targeting mitochondrial shape: at the heart of cardioprotection.

Sauri Hernandez-Resendiz, Aishwarya Prakash, Sze Jie Loo, Martina Semenzato, Kroekkiat Chinda, Gustavo E Crespo-Avilan, Linh Chi Dam, Shengjie Lu, Luca Scorrano, Derek J Hausenloy.

  There remains an unmet need to identify novel therapeutic strategies capable of protecting the myocardium against the detrimental effects of acute ischemia-reperfusion injury (IRI), to reduce myocardial infarct (MI) size and prevent the onset of heart failure (HF) following acute myocardial infarction (AMI). In this regard, perturbations in mitochondrial morphology with an imbalance in mitochondrial fusion and fission can disrupt mitochondrial metabolism, calcium homeostasis, and reactive oxygen species production, factors which are all known to be critical determinants of cardiomyocyte death following acute myocardial IRI. As such, therapeutic approaches directed at preserving the morphology and functionality of mitochondria may provide an important strategy for cardioprotection. In this article, we provide an overview of the alterations in mitochondrial morphology which occur in response to acute myocardial IRI, and highlight the emerging therapeutic strategies for targeting mitochondrial shape to preserve mitochondrial function which have the future therapeutic potential to improve health outcomes in patients presenting with AMI.

Keywords:  Acute myocardial infarction; Acute myocardial ischemia–reperfusion injury; Cardioprotection; Cardiovascular diseases; Heart failure; Mitochondrial morphology

DOI:  https://doi.org/10.1007/s00395-023-01019-9
Signal Transduct Target Ther. 2023 Nov 13. 8(1): 427

Transcriptional co-activators: emerging roles in signaling pathways and potential therapeutic targets for diseases.

Priyanka Dey Talukdar, Urmi Chatterji.

Specific cell states in metazoans are established by the symphony of gene expression programs that necessitate intricate synergic interactions between transcription factors and the co-activators. Deregulation of these regulatory molecules is associated with cell state transitions, which in turn is accountable for diverse maladies, including developmental disorders, metabolic disorders, and most significantly, cancer. A decade back most transcription factors, the key enablers of disease development, were historically viewed as 'undruggable'; however, in the intervening years, a wealth of literature validated that they can be targeted indirectly through transcriptional co-activators, their confederates in various physiological and molecular processes. These co-activators, along with transcription factors, have the ability to initiate and modulate transcription of diverse genes necessary for normal physiological functions, whereby, deregulation of such interactions may foster tissue-specific disease phenotype. Hence, it is essential to analyze how these co-activators modulate specific multilateral processes in coordination with other factors. The proposed review attempts to elaborate an in-depth account of the transcription co-activators, their involvement in transcription regulation, and context-specific contributions to pathophysiological conditions. This review also addresses an issue that has not been dealt with in a comprehensive manner and hopes to direct attention towards future research that will encompass patient-friendly therapeutic strategies, where drugs targeting co-activators will have enhanced benefits and reduced side effects. Additional insights into currently available therapeutic interventions and the associated constraints will eventually reveal multitudes of advanced therapeutic targets aiming for disease amelioration and good patient prognosis.

DOI: https://doi.org/10.1038/s41392-023-01651-w
PLoS One. 2023 ;18(11): e0293673

Female sex protects against renal edema, but not lung edema, in mice with partial deletion of the endothelial barrier regulator Tie2 compared to male sex.

Anoek L I van Leeuwen, Elise Beijer, Roselique Ibelings, Nicole A M Dekker, Marjolein R A van der Steen, Joris J T H Roelofs, Matijs van Meurs, Grietje Molema, Charissa E van den Brom.

BACKGROUND: The endothelial angiopoietin/Tie2 system is an important regulator of endothelial permeability and targeting Tie2 reduces hemorrhagic shock-induced organ edema in males. However, sexual dimorphism of the endothelium has not been taken into account. This study investigated whether there are sex-related differences in the endothelial angiopoietin/Tie2 system and edema formation.
METHODS: Adult male and female heterozygous Tie2 knockout mice (Tie2+/-) and wild-type controls (Tie2+/+) were included (n = 9 per group). Renal and pulmonary injury were determined by wet/dry weight ratio and H&E staining of tissue sections. Protein levels were studied in plasma by ELISA and pulmonary and renal mRNA expression levels by RT-qPCR.
RESULTS: In Tie2+/+ mice, females had higher circulating angiopoietin-2 (138%, p<0.05) compared to males. Gene expression of angiopoietin-1 (204%, p<0.01), angiopoietin-2 (542%, p<0.001) were higher in females compared to males in kidneys, but not in lungs. Gene expression of Tie2, Tie1 and VE-PTP were similar between males and females in both organs. Renal and pulmonary wet/dry weight ratio did not differ between Tie2+/+ females and males. Tie2+/+ females had lower circulating NGAL (41%, p<0.01) compared to males, whereas renal NGAL and KIM1 gene expression was unaffected. Interestingly, male Tie2+/- mice had 28% higher renal wet/dry weight ratio (p<0.05) compared to Tie2+/+ males, which was not observed in females nor in lungs. Partial deletion of Tie2 did not affect circulating angiopoietin-1 or angiopoietin-2, but soluble Tie2 was 44% and 53% lower in males and females, respectively, compared to Tie2+/+ mice of the same sex. Renal and pulmonary gene expression of angiopoietin-1, angiopoietin-2, estrogen receptors and other endothelial barrier regulators was comparable between Tie2+/- and Tie2+/+ mice in both sexes.
CONCLUSION: Female sex seems to protect against renal, but not pulmonary edema in heterozygous Tie2 knock-out mice. This could not be explained by sex dimorphism in the endothelial angiopoietin/Tie2 system.

DOI: https://doi.org/10.1371/journal.pone.0293673
Int J Mol Sci. 2023 Nov 06. pii: 16015. [Epub ahead of print]24(21):

Interrogating the Role of miR-125b and Its 3'isomiRs in Protection against Hypoxia.

Lee Lee Wong, Azizah Binti Fadzil, Qiying Chen, Miriam T Rademaker, Christopher J Charles, Arthur Mark Richards, Peipei Wang.

  MiR-125b has therapeutic potential in the amelioration of myocardial ischemic injury. MicroRNA isomiRs, with either 5' or 3' addition or deletion of nucleotide(s), have been reported from next-generation sequencing data (NGS). However, due to technical challenges, validation and functional studies of isomiRs are few. In this study, we discovered using NGS, four 3'isomiRs of miR-125b, i.e., addition of A (adenosine), along with deletions of A, AG (guanosine) and AGU (uridine) from rat and sheep heart. These findings were validated using RT-qPCR. Comprehensive functional studies were carried out in the H9C2 hypoxia model. After miR-125b, isomiRs of Plus A, Trim A, AG and AGU mimic transfection, the H9C2 cells were subjected to hypoxic challenge. As assessed using cell viability, apoptosis, CCK-8 and LDH release, miR-125b and isomiRs were all protective against hypoxia. However, Plus A and Trim A were more effective than miR-125b, whilst Trim AG and Trim AGU had far weaker effects than miR-125b. Interestingly, both the gene regulation profile and apoptotic gene validation indicated a major overlap among miR-125b, Plus A and Trim A, whilst Trims AG and AGU revealed a different profile compared to miR-125b. Conclusions: miR-125b and its 3' isomiRs are expressed stably in the heart. miR-125b and isomiRs with addition or deletion of A might function concurrently and concordantly under specific physiological and pathophysiological conditions. In-depth understanding of isomiRs' metabolism and function will contribute to better miRNA therapeutic drug design.

Keywords:  and apoptosis; hypoxia; isomiR; miR-125b; microRNA

DOI:  https://doi.org/10.3390/ijms242116015
Front Cell Dev Biol. 2023 ;11 1278166

Endothelial cell dysfunction in cardiac disease: driver or consequence?

Jules D Allbritton-King, Guillermo García-Cardeña.

  The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.

Keywords:  cardiomyocytes; endothelial cells; endothelial dysfunction; heart disease; paracrine signaling

DOI:  https://doi.org/10.3389/fcell.2023.1278166
Nat Commun. 2023 Nov 15. 14(1): 7291

PAX3-FOXO1 dictates myogenic reprogramming and rhabdomyosarcoma identity in endothelial progenitors.

Madeline B Searcy, Randolph K Larsen, Bradley T Stevens, Yang Zhang, Hongjian Jin, Catherine J Drummond, Casey G Langdon, Katherine E Gadek, Kyna Vuong, Kristin B Reed, Matthew R Garcia, Beisi Xu, Darden W Kimbrough, Grace E Adkins, Nadhir Djekidel, Shaina N Porter, Patrick A Schreiner, Shondra M Pruett-Miller, Brian J Abraham, Jerold E Rehg, Mark E Hatley.

Fusion-positive rhabdomyosarcoma (FP-RMS) driven by the expression of the PAX3-FOXO1 (P3F) fusion oncoprotein is an aggressive subtype of pediatric rhabdomyosarcoma. FP-RMS histologically resembles developing muscle yet occurs throughout the body in areas devoid of skeletal muscle highlighting that FP-RMS is not derived from an exclusively myogenic cell of origin. Here we demonstrate that P3F reprograms mouse and human endothelial progenitors to FP-RMS. We show that P3F expression in aP2-Cre expressing cells reprograms endothelial progenitors to functional myogenic stem cells capable of regenerating injured muscle fibers. Further, we describe a FP-RMS mouse model driven by P3F expression and Cdkn2a loss in endothelial cells. Additionally, we show that P3F expression in TP53-null human iPSCs blocks endothelial-directed differentiation and guides cells to become myogenic cells that form FP-RMS tumors in immunocompromised mice. Together these findings demonstrate that FP-RMS can originate from aberrant development of non-myogenic cells driven by P3F.

DOI: https://doi.org/10.1038/s41467-023-43044-1
bioRxiv. 2023 Nov 02. pii: 2023.10.31.564750. [Epub ahead of print]

The human mitochondrial mRNA structurome reveals mechanisms of gene expression.

J Conor Moran, Amir Brivanlou, Michele Brischigliaro, Flavia Fontanesi, Silvi Rouskin, Antoni Barrientos.

The mammalian mitochondrial genome encodes thirteen oxidative phosphorylation system proteins, crucial in aerobic energy transduction. These proteins are translated from 9 monocistronic and 2 bicistronic transcripts, whose native structures remain unexplored, leaving fundamental molecular determinants of mitochondrial gene expression unknown. To address this gap, we developed a mitoDMS-MaPseq approach and used DREEM clustering to resolve the native human mitochondrial mt-mRNA structurome. We gained insights into mt-mRNA biology and translation regulatory mechanisms, including a unique programmed ribosomal frameshifting for the ATP8/ATP6 transcript. Furthermore, absence of the mt-mRNA maintenance factor LRPPRC led to a mitochondrial transcriptome structured differently, with specific mRNA regions exhibiting increased or decreased structuredness. This highlights the role of LRPPRC in maintaining mRNA folding to promote mt-mRNA stabilization and efficient translation. In conclusion, our mt-mRNA folding maps reveal novel mitochondrial gene expression mechanisms, serving as a detailed reference and tool for studying them in different physiological and pathological contexts.

DOI: https://doi.org/10.1101/2023.10.31.564750
Sci Adv. 2023 Nov 17. 9(46): eadi5764

Centromere innovations within a mouse species.

Craig W Gambogi, Nootan Pandey, Jennine M Dawicki-McKenna, Uma P Arora, Mikhail A Liskovykh, Jun Ma, Piero Lamelza, Vladimir Larionov, Michael A Lampson, Glennis A Logsdon, Beth L Dumont, Ben E Black.

Mammalian centromeres direct faithful genetic inheritance and are typically characterized by regions of highly repetitive and rapidly evolving DNA. We focused on a mouse species, Mus pahari, that we found has evolved to house centromere-specifying centromere protein-A (CENP-A) nucleosomes at the nexus of a satellite repeat that we identified and termed π-satellite (π-sat), a small number of recruitment sites for CENP-B, and short stretches of perfect telomere repeats. One M. pahari chromosome, however, houses a radically divergent centromere harboring ~6 mega-base pairs of a homogenized π-sat-related repeat, π-satB, that contains >20,000 functional CENP-B boxes. There, CENP-B abundance promotes accumulation of microtubule-binding components of the kinetochore and a microtubule-destabilizing kinesin of the inner centromere. We propose that the balance of pro- and anti-microtubule binding by the new centromere is what permits it to segregate during cell division with high fidelity alongside the older ones whose sequence creates a markedly different molecular composition.

DOI: https://doi.org/10.1126/sciadv.adi5764