Browsing by Subject "Mitochondria / metabolism"
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Item Genetically-regulated transcriptomics & copy number variation of proctitis points to altered mitochondrial and DNA repair mechanisms in individuals of European ancestry(BioMed Central Ltd., 2020-10-02) Pathak, Gita A.; Polimanti, Renato; Silzer, Talisa K.; Wendt, Frank R.; Chakraborty, Ranajit; Phillips, Nicole R.BACKGROUND: Proctitis is an inflammation of the rectum and may be induced by radiation treatment for cancer. The genetic heritability of developing radiotoxicity and prior role of genetic variants as being associated with side-effects of radiotherapy necessitates further investigation for underlying molecular mechanisms. In this study, we investigated gene expression regulated by genetic variants, and copy number variation in prostate cancer survivors with radiotoxicity. METHODS: We investigated proctitis as a radiotoxic endpoint in prostate cancer patients who received radiotherapy (n = 222). We analyzed the copy number variation and genetically regulated gene expression profiles of whole-blood and prostate tissue associated with proctitis. The SNP and copy number data were genotyped on Affymetrix(R) Genome-wide Human SNP Array 6.0. Following QC measures, the genotypes were used to obtain gene expression by leveraging GTEx, a reference dataset for gene expression association based on genotype and RNA-seq information for prostate (n = 132) and whole-blood tissue (n = 369). RESULTS: In prostate tissue, 62 genes were significantly associated with proctitis, and 98 genes in whole-blood tissue. Six genes - CABLES2, ATP6AP1L, IFIT5, ATRIP, TELO2, and PARD6G were common to both tissues. The copy number analysis identified seven regions associated with proctitis, one of which (ALG1L2) was also associated with proctitis based on transcriptomic profiles in the whole-blood tissue. The genes identified via transcriptomics and copy number variation association were further investigated for enriched pathways and gene ontology. Some of the enriched processes were DNA repair, mitochondrial apoptosis regulation, cell-to-cell signaling interaction processes for renal and urological system, and organismal injury. CONCLUSIONS: We report gene expression changes based on genetic polymorphisms. Integrating gene-network information identified these genes to relate to canonical DNA repair genes and processes. This investigation highlights genes involved in DNA repair processes and mitochondrial malfunction possibly via inflammation. Therefore, it is suggested that larger studies will provide more power to infer the extent of underlying genetic contribution for an individual's susceptibility to developing radiotoxicity.Item Modulation of Mitochondrial Metabolic Parameters and Antioxidant Enzymes in Healthy and Glaucomatous Trabecular Meshwork Cells with Hybrid Small Molecule SA-2(MDPI, 2023-07-29) Amankwa, Charles E.; Young, Olivia; DebNath, Biddut; Gondi, Sudershan R.; Rangan, Rajiv; Ellis, Dorette Z.; Zode, Gulab S.; Stankowska, Dorota L.; Acharya, SuchismitaOxidative stress (OS)-induced mitochondrial damage is a risk factor for primary open-angle glaucoma (POAG). Mitochondria-targeted novel antioxidant therapies could unearth promising drug candidates for the management of POAG. Previously, our dual-acting hybrid molecule SA-2 with nitric oxide-donating and antioxidant activity reduced intraocular pressure and improved aqueous humor outflow in rodent eyes. Here, we examined the mechanistic role of SA-2 in trabecular meshwork (TM) cells in vitro and measured the activity of intracellular antioxidant enzymes during OS. Primary human TM cells isolated from normal (hNTM) or glaucomatous (hGTM) post-mortem donors and transformed glaucomatous TM cells (GTM-3) were used for in vitro assays. We examined the effect of SA-2 on oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in vitro using Seahorse Analyzer with or without the oxidant, tert-butyl hydroperoxide (TBHP) treatment. Concentrations of total antioxidant enzymes, catalase (CAT), malondialdehyde (MDA), and glutathione peroxidase (GPx) were measured. We observed significant protection of both hNTM and hGTM cells from TBHP-induced cell death by SA-2. Antioxidant enzymes were elevated in SA-2-treated cells compared to TBHP-treated cells. In addition, SA-2 demonstrated an increase in mitochondrial metabolic parameters. Altogether, SA-2 protected both normal and glaucomatous TM cells from OS via increasing mitochondrial energy parameters and the activity of antioxidant enzymes.Item NADH/NAD(+) Redox Imbalance and Diabetic Kidney Disease(MDPI, 2021-05-14) Yan, Liang-JunDiabetic kidney disease (DKD) is a common and severe complication of diabetes mellitus. If left untreated, DKD can advance to end stage renal disease that requires either dialysis or kidney replacement. While numerous mechanisms underlie the pathogenesis of DKD, oxidative stress driven by NADH/NAD(+) redox imbalance and mitochondrial dysfunction have been thought to be the major pathophysiological mechanism of DKD. In this review, the pathways that increase NADH generation and those that decrease NAD(+) levels are overviewed. This is followed by discussion of the consequences of NADH/NAD(+) redox imbalance including disruption of mitochondrial homeostasis and function. Approaches that can be applied to counteract DKD are then discussed, which include mitochondria-targeted antioxidants and mimetics of superoxide dismutase, caloric restriction, plant/herbal extracts or their isolated compounds. Finally, the review ends by pointing out that future studies are needed to dissect the role of each pathway involved in NADH-NAD(+) metabolism so that novel strategies to restore NADH/NAD(+) redox balance in the diabetic kidney could be designed to combat DKD.Item Peroxisome proliferator-activated receptor-alpha (PPARalpha) regulates wound healing and mitochondrial metabolism in the cornea(National Academy of Science, 2023-03-22) Liang, Wentao; Huang, Li; Whelchel, Amy E.; Yuan, Tian; Ma, Xiang; Cheng, Rui; Takahashi, Yusuke; Karamichos, Dimitrios; Ma, Jian-XingDiabetes can result in impaired corneal wound healing. Mitochondrial dysfunction plays an important role in diabetic complications. However, the regulation of mitochondria function in the diabetic cornea and its impacts on wound healing remain elusive. The present study aimed to explore the molecular basis for the disturbed mitochondrial metabolism and subsequent wound healing impairment in the diabetic cornea. Seahorse analysis showed that mitochondrial oxidative phosphorylation is a major source of ATP production in human corneal epithelial cells. Live corneal biopsy punches from type 1 and type 2 diabetic mouse models showed impaired mitochondrial functions, correlating with impaired corneal wound healing, compared to nondiabetic controls. To approach the molecular basis for the impaired mitochondrial function, we found that Peroxisome Proliferator-Activated Receptor-alpha (PPARalpha) expression was downregulated in diabetic human corneas. Even without diabetes, global PPARalpha knockout mice and corneal epithelium-specific PPARalpha conditional knockout mice showed disturbed mitochondrial function and delayed wound healing in the cornea, similar to that in diabetic corneas. In contrast, fenofibrate, a PPARalpha agonist, ameliorated mitochondrial dysfunction and enhanced wound healing in the corneas of diabetic mice. Similarly, corneal epithelium-specific PPARalpha transgenic overexpression improved mitochondrial function and enhanced wound healing in the cornea. Furthermore, PPARalpha agonist ameliorated the mitochondrial dysfunction in primary human corneal epithelial cells exposed to diabetic stressors, which was impeded by siRNA knockdown of PPARalpha, suggesting a PPARalpha-dependent mechanism. These findings suggest that downregulation of PPARalpha plays an important role in the impaired mitochondrial function in the corneal epithelium and delayed corneal wound healing in diabetes.Item The mitochondrial UPR regulator ATF5 promotes intestinal barrier function via control of the satiety response(Elsevier B.V., 2022-12-15) Chamseddine, Douja; Mahmud, Siraje A.; Westfall, Aundrea K.; Castoe, Todd A.; Berg, Rance E.; Pellegrino, Mark W.Organisms use several strategies to mitigate mitochondrial stress, including the activation of the mitochondrial unfolded protein response (UPR(mt)). The UPR(mt) in Caenorhabditis elegans, regulated by the transcription factor ATFS-1, expands on this recovery program by inducing an antimicrobial response against pathogens that target mitochondrial function. Here, we show that the mammalian ortholog of ATFS-1, ATF5, protects the host during infection with enteric pathogens but, unexpectedly, by maintaining the integrity of the intestinal barrier. Intriguingly, ATF5 supports intestinal barrier function by promoting a satiety response that prevents obesity and associated hyperglycemia. This consequently averts dysregulated glucose metabolism that is detrimental to barrier function. Mechanistically, we show that intestinal ATF5 stimulates the satiety response by transcriptionally regulating the gastrointestinal peptide hormone cholecystokinin, which promotes the secretion of the hormone leptin. We propose that ATF5 protects the host from enteric pathogens by promoting intestinal barrier function through a satiety-response-mediated metabolic control mechanism.