Expression and functional activity of pro-oxidants and antioxidants in murine heart exposed to acute hypobaric hypoxia

AbstractUnder hypobaric hypoxia, antioxidant defenses of the heart are stressed by the enhanced production of ROS. Mammalian heart acclimatizes to hypoxia through altered gene expression, which we studied in murine heart exposed to 10h of acute hypobaric hypoxia (AHH), equivalent to 15000ft, using cDNA arrays. Functional classification of genes with a ⩾2-fold change revealed a number of pro-oxidants like Cyba, Xdh, Txnip, Ppp1r15b and antioxidants like Cat, Gpx1, Mt1, Mgst1. Interestingly, the protein level of Cyba, a subunit of NADPH oxidase, was markedly decreased in AHH exposed heart, suggesting the involvement of some stress response pathways. The AHH exposure also caused a significant reduction (50%) in the level of GSH (P<0.05). The present study provides a retrospective insight on the cellular antioxidant defense mechanisms under AHH

Risk Factors and Secondary Infections in Dengue Hemorrhagic Fever Patients

Background: Dengue hemorrhagic fever (DHF) is a fatal manifestation of dengue disease. DHF’s risk factors profile holds significance importance in the clinical practice and efficient care plan are required during dengue disease flare-up. The aim of this study was to investigate the risk factors for pathogenesis of dengue disease and dengue hemorrhagic fever. Methods: In this descriptive cross-sectional study, data was obtained from 256 patients with diagnoses of Dengue hemorrhagic fever (DHF). Comprehensive history, physical assessment and biochemical estimations were recorded. Patients were followed to identify and assess the risk factors for DHF. The Statistical Package of Social Sciences for analysis of data. Stratification of residence and socioeconomic status to see effect of these on result variable by applying chi square test. p value of <0.05 was taken as significant. Results: Among the 256 patients, the mean age of the age (Mean±SD) of study population was 28.4±12.1 years, 162 (63.28%) were less than 40 years of age and 94 (36.72%) were ≥40 years. The males were 181 (70.70%) and females were 75 (29.30%). The frequency of risk factors was observed to be 26 (10.8%) patients had Diabetes Mellitus, 55(21.5%) hypertension, 25(9.8%) hyperlipidemia. Secondary infection occurred in 192 (75%) but results were insignificant (p>0.05). All diseases were common in participants who belonged to the urban area. Conclusion: Secondary infection was most common risk factor in patients with DHF and found mostly in less than 40 age than older patients. Whereas, males were predominately affected more than the females (p<0.05). Keywords: Severe Dengue, Dengue Hemorrhagic Fever, Risk Factor

Mitochondrial calcium exchange links metabolism with the epigenome to control cellular differentiation.

Fibroblast to myofibroblast differentiation is crucial for the initial healing response but excessive myofibroblast activation leads to pathological fibrosis. Therefore, it is imperative to understand the mechanisms underlying myofibroblast formation. Here we report that mitochondrial calcium (mCa2+) signaling is a regulatory mechanism in myofibroblast differentiation and fibrosis. We demonstrate that fibrotic signaling alters gating of the mitochondrial calcium uniporter (mtCU) in a MICU1-dependent fashion to reduce mCa2+ uptake and induce coordinated changes in metabolism, i.e., increased glycolysis feeding anabolic pathways and glutaminolysis yielding increased α-ketoglutarate (αKG) bioavailability. mCa2+-dependent metabolic reprogramming leads to the activation of αKG-dependent histone demethylases, enhancing chromatin accessibility in loci specific to the myofibroblast gene program, resulting in differentiation. Our results uncover an important role for the mtCU beyond metabolic regulation and cell death and demonstrate that mCa2+ signaling regulates the epigenome to influence cellular differentiation

A Novel CLCN5 Mutation Associated With Focal Segmental Glomerulosclerosis and Podocyte Injury

Introduction: Tubular dysfunction is characteristic of Dent's disease; however, focal segmental glomerulosclerosis (FSGS) can also be present. Glomerulosclerosis could be secondary to tubular injury, but it remains uncertain whether the CLCN5 gene, which encodes an endosomal chloride and/or hydrogen exchanger, plays a role in podocyte biology. Here, we implicate a role for CLCN5 in podocyte function and pathophysiology.Methods: Whole exome capture and sequencing of the proband and 5 maternally-related family members was conducted to identify X-linked mutations associated with biopsy-proven FSGS. Human podocyte cultures were used to characterize the mutant phenotype on podocyte function.Results: We identified a novel mutation (L521F) in CLCN5 in 2 members of a Hispanic family who presented with a histologic diagnosis of FSGS and low-molecular-weight proteinuria without hypercalciuria. Presence of CLCN5 was confirmed in cultured human podocytes. Podocytes transfected with the wild-type or the mutant (L521F) CLCN5 constructs showed differential localization. CLCN5 knockdown in podocytes resulted in defective transferrin endocytosis and was associated with decreased cell proliferation and increased cell migration, which are hallmarks of podocyte injury.Conclusions: The CLCN5 mutation, which causes Dent's disease, may be associated with FSGS without hyercalcuria and nepthrolithiasis. The present findings supported the hypothesis that CLCN5 participates in protein trafficking in podocytes and plays a critical role in organizing the components of the podocyte slit diaphragm to help maintain normal cell physiology and a functional filtration barrier. In addition to tubular dysfunction, mutations in CLCN5 may also lead to podocyte dysfunction, which results in a histologic picture of FSGS that may be a primary event and not a consequence of tubular damage

Loss of Motor Protein MYO1C Causes Rhodopsin Mislocalization and Results in Impaired Visual Function

Unconventional myosins, linked to deafness, are also proposed to play a role in retinal cell physiology. However, their direct role in photoreceptor function remains unclear. We demonstrate that systemic loss of the unconventional myosin MYO1C in mice, specifically causes rhodopsin mislocalization, leading to impaired visual function. Electroretinogram analysis of Myo1c knockout (Myo1c-KO) mice showed a progressive loss of photoreceptor function. Immunohistochemistry and binding assays demonstrated MYO1C localization to photoreceptor inner and outer segments (OS) and identified a direct interaction of rhodopsin with MYO1C. In Myo1c-KO retinas, rhodopsin mislocalized to rod inner segments (IS) and cell bodies, while cone opsins in OS showed punctate staining. In aged mice, the histological and ultrastructural examination of the phenotype of Myo1c-KO retinas showed progressively shorter photoreceptor OS. These results demonstrate that MYO1C is important for rhodopsin localization to the photoreceptor OS, and for normal visual function

Targeting Myosin 1c Inhibits Murine Hepatic Fibrogenesis

Myosin 1c (Myo1c) is an unconventional myosin that modulates signaling pathways involved in tissue injury and repair. In this study, we observed that Myo1c expression is significantly upregulated in human chronic liver disease such as nonalcoholic steatohepatitis (NASH) and in animal models of liver fibrosis. High throughput data from the GEO-database identified similar Myo1c upregulation in mice and human liver fibrosis. Notably, TGF-β stimulation to hepatic stellate cells (HSCs, the liver pericyte and key cell type responsible for the deposition of extracellular matrix upregulates Myo1c expression, while genetic depletion or pharmacological inhibition of Myo1c blunted TGF-β induced fibrogenic responses, resulting in repression of α-SMA and Col1α1 mRNA. Myo1c deletion also decreased fibrogenic processes such as cell proliferation, wound healing response and contractility when compared with vehicle treated HSCs. Importantly, phosphorylation of SMAD2 and SMAD3 were significantly blunted upon Myo1c inhibition in GRX cells as well as Myo1c-KO MEFs upon TGF-β stimulation. Using the genetic Myo1c knockout (Myo1c-KO) mice, we confirmed that Myo1c is critical for fibrogenesis as Myo1c-KO mice were resistant to CCl4 induced liver fibrosis. Histological and immunostaining analysis of liver sections showed that deposition of collagen fibers and α-SMA expression were significantly reduced in Myo1c-KO mice upon liver injury. Collectively, these results demonstrate that Myo1c-mediates hepatic fibrogenesis by modulating TGF-β signaling and suggest that inhibiting this process may have clinical application in treating liver fibrosis