Alternative start codon is associated to production of human non‐hypusinated EIF5A1 isoform A

Sem informação29

Alternative human eIF5A protein isoform plays a critical role in mitochondria

The eukaryotic translation initiation factor 5A (eIF5A) is the only known protein containing the amino acid residue hypusine, essential for its activity. Hypusine residue is produced by a posttranslational modification involving deoxyhypusine synthetase and deoxyhypusine hydroxylase. Herein, we aimed to describe the role of the alternative human isoform A on mitochondrial processes. Isoform A depletion modulates oxidative metabolism in association with the downregulation of mitochondrial biogenesis‐related genes. Through positive feedback, it increases cell respiration leading to highly reactive oxygen species production, which impacts mitochondrial bioenergetics. These metabolic changes compromise mitochondrial morphology, increasing its electron density and fission, observed by transmission electron microscopy. This set of changes leads the cells to apoptosis, evidenced by increased DNA fragmentation and proapoptotic BAK protein content increase. Thus, we show that the alternative eIF5A isoform A is crucial for energy metabolism controlled by mitochondria and cellular survivalOnline Version of Record before inclusion in an issu

Modulation of miR-26a-5p and miR-15b-5p Exosomal Expression Associated with Clopidogrel-Induced Hepatotoxicity in HepG2 Cells

Clopidogrel is an essential antiplatelet drug used to prevent thrombosis complications associated with atherosclerosis. However, hepatotoxicity is a potential adverse effect related to clopidogrel therapy. Exosome-derived miRNAs may be useful for improved monitoring of drug response and hepatotoxicity risk. In the present study, the expression of several exosomal miRNAs (miR-26a-5p, miR-145-5p, miR-15b-5p, and miR-4701-3p) and cell-derived mRNA targets (PLOD2, SENP5, EIF4G2, HMGA2, STRADB, and TLK1) were evaluated in HepG2 cells treated with clopidogrel (6.25, 12.5, 25, 50, and 100 μM) for 24 and 48 h. Then, clopidogrel cytotoxicity was evaluated by analyzing DNA fragmentation and the cell cycle profile using flow cytometry. Differential expression of exosome-derived miRNAs and cell-derived mRNAs was analyzed by RT-qPCR. Exposure of HepG2 cells to high concentrations of clopidogrel (50 and 100 μM) for 24 h caused significant DNA fragmentation (17.6 and 44.4%, respectively; p < 0.05) and 48 h (26.8 and 48.9%, respectively; p < 0.05), indicating cellular toxicity. Upregulation of miR-26a-5p and downregulation of miR-15b-5p was observed in cells exposed to 100 μM clopidogrel for 24 and 48 h. The miR-26a-5p target mRNAs HMGA2, EIF4G2, STRADB, and SENP5 were downregulated in HepG2 cells following exposure to cytotoxic concentrations of clopidogrel (50 and 100 μM) for 24 h, and HMGA2 levels remained low after 48 h of treatment. TLK1, a target of miR-15b-5p, was downregulated by 50 and 100 μM clopidogrel at 24 h. In conclusion, our results suggest that exposure to high concentrations of clopidogrel modulates the expression of exosomal miR-26a-5p and miR-15b-5p and their target mRNAs in HepG2 cells. Dysregulation of these miRNAs maybe modulate the regulatory pathways involved in clopidogrel-induced liver injury

Loss of Parkin Results in Altered Muscle Stem Cell Differentiation during Regeneration.

The high capacity of the skeletal muscle to regenerate is due to the presence of muscle stem cells (MuSCs, or satellite cells). The E3 ubiquitin ligase Parkin is a key regulator of mitophagy and is recruited to mitochondria during differentiation of mouse myoblast cell line. However, the function of mitophagy during regeneration has not been investigated in vivo. Here, we have utilized Parkin deficient (Parkin-/-) mice to investigate the role of Parkin in skeletal muscle regeneration. We found a persistent deficiency in skeletal muscle regeneration in Parkin-/- mice after cardiotoxin (CTX) injury with increased area of fibrosis and decreased cross-sectional area (CSA) of myofibres post-injury. There was also a significant modulation of MuSCs differentiation and mitophagic markers, with altered mitochondrial proteins during skeletal muscle regeneration in Parkin-/- mice. Our data suggest that Parkin-mediated mitophagy plays a key role in skeletal muscle regeneration and is necessary for MuSCs differentiation

Loss of Parkin Results in Altered Muscle Stem Cell Differentiation during Regeneration.

The high capacity of the skeletal muscle to regenerate is due to the presence of muscle stem cells (MuSCs, or satellite cells). The E3 ubiquitin ligase Parkin is a key regulator of mitophagy and is recruited to mitochondria during differentiation of mouse myoblast cell line. However, the function of mitophagy during regeneration has not been investigated in vivo. Here, we have utilized Parkin deficient (Parkin-/-) mice to investigate the role of Parkin in skeletal muscle regeneration. We found a persistent deficiency in skeletal muscle regeneration in Parkin-/- mice after cardiotoxin (CTX) injury with increased area of fibrosis and decreased cross-sectional area (CSA) of myofibres post-injury. There was also a significant modulation of MuSCs differentiation and mitophagic markers, with altered mitochondrial proteins during skeletal muscle regeneration in Parkin-/- mice. Our data suggest that Parkin-mediated mitophagy plays a key role in skeletal muscle regeneration and is necessary for MuSCs differentiation