Differential impact of sex on regulation of skeletal muscle mitochondrial function and protein homeostasis by hypoxia-inducible factor-1α in normoxia.

Hypoxia-inducible factor (HIF)-1α is continuously synthesized and degraded in normoxia. During hypoxia, HIF1α stabilization restricts cellular/mitochondrial oxygen utilization. Cellular stressors can stabilize HIF1α even during normoxia. However, less is known about HIF1α function(s) and sex-specific effects during normoxia in the basal state. Since skeletal muscle is the largest protein store in mammals and protein homeostasis has high energy demands, we determined HIF1α function at baseline during normoxia in skeletal muscle. Untargeted multiomics data analyses were followed by experimental validation in differentiated murine myotubes with loss/gain of function and skeletal muscle from mice without/with post-natal muscle-specific Hif1a deletion (Hif1amsd). Mitochondrial oxygen consumption studies using substrate, uncoupler, inhibitor, titration protocols; targeted metabolite quantification by gas chromatography-mass spectrometry; and post-mitotic senescence markers using biochemical assays were performed. Multiomics analyses showed enrichment in mitochondrial and cell cycle regulatory pathways in Hif1a deleted cells/tissue. Experimentally, mitochondrial oxidative functions and ATP content were higher with less mitochondrial free radical generation with Hif1a deletion. Deletion of Hif1a also resulted in higher concentrations of TCA cycle intermediates and HIF2α proteins in myotubes. Overall responses to Hif1amsd were similar in male and female mice, but changes in complex II function, maximum respiration, Sirt3 and HIF1ß protein expression and muscle fibre diameter were sex-dependent. Adaptive responses to hypoxia are mediated by stabilization of constantly synthesized HIF1α. Despite rapid degradation, the presence of HIF1α during normoxia contributes to lower mitochondrial oxidative efficiency and greater post-mitotic senescence in skeletal muscle. In vivo responses to HIF1α in skeletal muscle were differentially impacted by sex. KEY POINTS: Hypoxia-inducible factor -1α (HIF1α), a critical transcription factor, undergoes continuous synthesis and proteolysis, enabling rapid adaptive responses to hypoxia by reducing mitochondrial oxygen consumption. In mammals, skeletal muscle is the largest protein store which is determined by a balance between protein synthesis and breakdown and is sensitive to mitochondrial oxidative function. To investigate the functional consequences of transient HIF1α expression during normoxia in the basal state, myotubes and skeletal muscle from male and female mice with HIF1α knockout were studied using complementary multiomics, biochemical and metabolite assays. HIF1α knockout altered the electron transport chain, mitochondrial oxidative function, signalling molecules for protein homeostasis, and post-mitotic senescence markers, some of which were differentially impacted by sex. The cost of rapid adaptive responses mediated by HIF1α is lower mitochondrial oxidative efficiency and post-mitotic senescence during normoxia.

Gymnemic acid protects murine pancreatic ß-cells by moderating hyperglycemic stress-induced inflammation and apoptosis in type 1 diabetic rats.

Type 1 diabetes is a chronic immune-mediated disease caused by pancreatic ß-cell dysfunction with consequent severe insulin deficiency. Exacerbated blood glucose levels can cause oxidative stress in the pancreatic ß-cells, which leads to inflammation, and apoptosis resulting in islet dysfunction. Although massive studies have been carried out to elucidate the causative factors for ß-cell damage in diabetes, the therapeutic approach to pancreatic ß-cell damage has not been extensively studied. Hence, the present study has been designed to delineate the role of gymnemic acid (GA) in protecting pancreatic ß-cells in diabetic animals, with special reference to inflammation and apoptosis. Our data revealed that the treatment with GA significantly reverted the alteration in both biochemical and histochemical observations in young diabetic rats. Moreover, treatment with the GA downregulates the expression of proinflammatory markers (nuclear factor-κB, tumor necrosis factor-α, interleukin-[IL]-6, and IL-1ß), proapoptotic proteins (Bax, cytochrome c, and cleaved caspase-3), as well as upregulates the expression of antiapoptotic protein Bcl-2 in diabetic rats. These findings suggest that the anti-inflammatory and antiapoptotic nature of GA mitigates ß-cell damage in hyperglycemic rats.

Gymnemic Acid Ameliorates Pancreatic ß-Cell Dysfunction by Modulating Pdx1 Expression: A Possible Strategy for ß-Cell Regeneration.

BACKGROUND: Endogenous pancreatic ß-cell regeneration is a promising therapeutic approach for enhancing ß-cell function and neogenesis in diabetes. Various findings have reported that regeneration might occur via stimulating ß-cell proliferation, neogenesis, or conversion from other pancreatic cells to ß-like cells. Although the current scenario illustrates numerous therapeutic strategies and approaches that concern endogenous ß-cell regeneration, all of them have not been successful to a greater extent because of cost effectiveness, availability of suitable donors and rejection in case of transplantation, or lack of scientific evidence for many phytochemicals derived from plants that have been employed in traditional medicine. Therefore, the present study aims to investigate the effect of gymnemic acid (GA) on ß-cell regeneration in streptozotocin-induced type 1 diabetic rats and high glucose exposed RIN5-F cells. METHODS: The study involves histopathological and immunohistochemical analysis to examine the islet's architecture. Quantitative polymerase chain reaction (qPCR) and/or immunoblot were employed to quantify the ß-cell regeneration markers and cell cycle proliferative markers. RESULTS: The immunoexpression of E-cadherin, ß-catenin, and phosphoinositide 3-kinases/protein kinase B were significantly increased in GA-treated diabetic rats. On the other hand, treatment with GA upregulated the pancreatic regenerative transcription factor viz. pancreatic duodenal homeobox 1, Neurogenin 3, MafA, NeuroD1, and ß-cells proliferative markers such as CDK4, and Cyclin D1, with a simultaneous downregulation of the forkhead box O, glycogen synthase kinase-3, and p21cip1 in diabetic treated rats. Adding to this, we noticed increased nuclear localization of Pdx1 in GA treated high glucose exposed RIN5-F cells. CONCLUSION: Our results suggested that GA acts as a potential therapeutic candidate for endogenous ß-cell regeneration in treating type 1 diabetes.

A Rare Genetic Mutation in a Stone Former.

A 30-year-old woman with history of passage of stones since childhood presented with oliguria and pedal edema for 10 days. She had hypertension with a creatinine of 4.1 mg/dL. Evaluation showed presence of bilateral multiple renal calculi with features of chronicity of kidney disease. Metabolic work-up for nephrolithiasis turned out to be negative and eventually renal biopsy revealed features of chronic interstitial nephritis with greenish brown refractile crystals in the tubular lumen and interstitium. The possibility of dihydroxy adenine crystalline nephropathy was considered. Spectrophotometry of RBC lysates revealed decreased activity of Adenine phosphoribosyl-transferase enzyme. Gene amplification by PCR and sequential analysis identified a missense mutation in exon 3 region of APRT gene in the patient and her family members. This case report highlights the need to contemplate the diagnosis of DHA crystalline nephropathy in young patients with nephrolithiasis and the identification of a rare genetic mutation, which is being reported for the first time in India.

Potential Chemopreventive Role of Boldine Against Hepatocellular Carcinoma via Modulation of Cell Cycle Proteins in Rat Model.

BACKGROUND: To evaluate the chemopreventive potential of boldine against diethylnitrosamine (DEN) induced hepatocellular carcinoma (HCC) in Wistar albino rats. OBJECTIVE: Boldine is an alkaloid isolated from Peumus boldus. The primary active constituents of boldine exhibited several potential medicinal properties. The present study was evaluated to explore the chemopreventive agent of boldine on anti-proliferative efficacy against diethylnitrosamine (DEN) induced hepatocellular carcinoma (HCC) in Wistar albino rats. METHODS: The effect of boldine on cellular proliferative markers, i.e., PCNA and Ki67on hepatocellular carcinoma rats was determined by immuno expression study. Liver marker enzymes, tumor biomarker, oxidative stress markers, antioxidant status, and xenobiotic phase I and II enzymes in HCC rats were analyzed. Moreover, cell cycle proteins, i.e., p21Cip1/Kip1and p27 Cip1/Kip1, Cyclin D1, CDK 4, Cyclin E1, and CDK 2 were investigated using immuno expression analysis. RESULTS: Treatment of boldine protected the liver against reactive oxygen species such as hydrogen peroxide, superoxide, protein carbonyl, and lipid peroxide during hepatocarcinogenesis by boosted antioxidants-superoxide dismutase (SOD), catalase (CAT). Boldine caused a substantial enhanced detoxification process by moderating phase I and II xenobiotic-metabolizing enzymes. Besides, the study found that boldine significantly inhibited the cellular proliferative markers like PCNA and Ki67 and regulated the specific cell cycle-associated proteins by up-regulated expression of p21Cip1/Kip1and p27 Cip1/Kip1 and down-regulated expression of Cyclin D1, CDK 4, Cyclin E1, and CDK 2. CONCLUSION: Our data manifests the anti-proliferative effect of boldine, which negatively modulates cellular proliferation and regulates cell cycle by protecting the cell from reactive oxygen species (ROS), suggesting that boldine establishes it as a chemopreventive agent in diethylnitrosamine-induced hepatocarcinogenesis in rats.

Role of Nrf2 dysfunction in the pathogenesis of diabetic nephropathy: Therapeutic prospect of epigallocatechin-3-gallate.

Diabetic nephropathy (DN), a progressive kidney disease afflicts more than 20 and up to 40% of the diabetic population and it is characterized by persistent microalbuminuria declined glomerular filtration rate. The interesting feature associated with DN is that, even though the progression of the disease correlates with oxidative stress, Nrf2, the master regulator of antioxidant defense system involved in counteracting oxidative stress is also upregulated in the diabetic kidneys of both human as well as experimental animals in early stages of DN. Despite the increased expression, the ability of this protein to get translocated into the nucleus is diminished signifying the functional impairment of Nrf2, implying redox imbalance. Hence, it is understood that agents that boost the translocation of Nrf2 might be beneficial rather than those that quantitatively overexpress Nrf2 in treating DN. The deleterious effects of synthetic Nrf2 activators have instigated the researchers to search for phytochemicals that have ambient Nrf2 boosting ability with no side effects, one such phytochemical is Epigallocatechin-3-gallate (EGCG) and it has shown beneficial effects by preventing the progression of DN via influencing Nrf2/ARE pathway, however, the modus operandi is unclear, despite speculations. This study was designed to find out whether supplementation of Nrf2 booster like EGCG at the crucial time of Nrf2 dysfunction can mitigate the progression of DN. Based on the findings of the present study, it might be concluded that the beneficial effect of EGCG in mitigating DN is mediated mainly through its ability to activate the Nrf2/ARE signaling pathway at multiple stages i.e., by downregulating Keap1 and boosting the nuclear Nrf2 level by disrupting Nrf2-Keap1 interaction. These results emphasize that supplementation of EGCG might be more beneficial at an early stage of DN, where dysfunctional Nrf2 accumulation occurs, which should be further validated.

Hepatoprotective effect of boldine against diethylnitrosamine-induced hepatocarcinogenesis in wistar rats.

Discovering the utmost effective and targeted chemotherapy for hepatocellular carcinoma is still a significant challenge. In the present study, diethylnitrosamine was used as a liver carcinogen and boldine a compound of boldo. We anticipated the hypothesis that boldine endow antiproliferative and promote apoptosis on hepatocarcinoma rats. We analyzed that boldine alters the tumor biomarkers and liver markers enzyme levels. Also, we determined boldine modulate the enzymatic and nonenzymatic antioxidant activities, as well as messenger RNA and protein expressions of Bcl2, Bax, and cleaved caspase 3 by reverse transcription polymerase chain reaction and Western blot analysis, respectively. It was also manifested by histopathology studies in liver tissues of HCC rats. Our finding suggested that boldine has antioxidant activity, and moreover, also contributes apoptotic nature by upregulating the protein expression of Bax, and cleaved caspase 3. Our data accomplishes that boldine a candidate drug has dynamic therapeutic activity and suitable for the treatment of HCC.