ResearchPad - cellular-and-molecular-physiology https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Distinct iron homeostasis in C57BL/6 and Balb/c mouse strains]]> https://www.researchpad.co/article/N567d8dc8-9bb5-4cb4-9865-61edda999224 Relative to C57BL/6 mice (BL6), Balb/c mice harbor more circulating, tissue and labile iron pool (LIP), which correlates with their generally heightened expression of key iron‐regulatory proteins like divalent metal transporter 1 (DMT1) andferroportin. Accordingly, such strain‐level differences in iron homeostasis could explain the dissimilar degree of developing pro‐inflammatory responses, followed by hypoferremia, in response to inflammatory challenge like lipopolysaccharides (LPS), which occurs more rapidly in BL6 mice than Balb/c mice.

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<![CDATA[Altered proteomics profile in the amnion of patients with oligohydramnios]]> https://www.researchpad.co/article/N99378a5b-0e9c-4e98-b614-8c3f09ac9275

Abstract

In pregnancy, idiopathic oligohydramnios is an obstetrical complication that compromises maternal health with poor perinatal outcome. Effective therapeutic treatment of this condition has been hampered by the unknown etiology and lack of understanding of cellular and molecular mechanisms that underlie idiopathic oligohydramnios. Amniotic fluid volume (AFV) is determined by intramembranous (IM) transport of amniotic fluid across the amnion and this pathway is regulated to maintain AFV within the normal range. To gain understanding of the causes of idiopathic oligohydramnios, we performed proteomics analysis of the human amnion to investigate the changes in protein expression profiles of cellular transport pathways and regulators in patients with oligohydramnios. Placental amnions from five patients with normal pregnancies and five patients with oligohydramnios were subjected to proteomics experiments followed by bioinformatics analysis. Using Ingenuity Pathway Analysis (IPA) software, five categories of biological functions and multiple canonical pathways within each category were revealed. The top differentially expressed proteins that participate in mediating these pathways were identified. The functional pathways activated include: (a) cellular assembly and organization, (b) cell signaling and energy metabolism, and (c) immunological, infectious, and inflammatory functions. Furthermore, the analysis identified the category of pathways that facilitate molecular endocytosis and vesicular uptake. Under oligohydramniotic conditions, the mediators of clathrin vesicle‐mediated uptake and transport as well as intracellular trafficking mediators were up‐regulated. These findings suggest that idiopathic oligohydramnios may be associated with alternations in cellular organization and immunological functions as well as increases in activity of vesicular transport pathways across the amnion.

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<![CDATA[Hepatic insulin sensitivity is improved in high‐fat diet‐fed Park2 knockout mice in association with increased hepatic AMPK activation and reduced steatosis]]> https://www.researchpad.co/article/Ndfc3e4dc-b4b9-4509-b217-fb1c52000c0f

Abstract

Park2 is an E3 ubiquitin ligase known for its role in mitochondrial quality control via the mitophagy pathway. Park2 KO mice are protected from diet‐induced obesity and hepatic insulin sensitivity is improved in high‐fat diet (HFD)‐fed Park2 KO mice even under body weight‐matched conditions. In order to better understand the cellular mechanism by which Park2 KO mice are protected from diet‐induced hepatic insulin resistance, we determined changes in multiple pathways commonly associated with the pathogenesis of insulin resistance, namely levels of bioactive lipid species, activation of the endoplasmic reticulum (ER) stress response and changes in cytokine levels and signaling. We report for the first time that whole‐body insulin sensitivity is unchanged in regular chow (RC)‐fed Park2 KO mice, and that liver diacylglycerol levels are reduced and very‐long‐chain ceramides are increased in Park2 KO mice fed HFD for 1 week. Hepatic transcriptional markers of the ER stress response were reduced and plasma tumor necrosis factor‐α (TNFα), interleukin‐6 and −10 (IL6, IL10) were significantly increased in HFD‐fed Park2 KO mice; however, there were no detectable differences in hepatic inflammatory signaling pathways between groups. Interestingly, hepatic adenylate charge was reduced in HFD‐fed Park2 KO liver and was associated increased activation of AMPK. These data suggest that negative energy balance that contributed to protection from obesity during chronic HFD manifested at the level of the hepatocyte during short‐term HFD feeding and contributed to the improved hepatic insulin sensitivity.

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<![CDATA[Alpha‐calcitonin gene‐related peptide prevents pressure‐overload induced heart failure: role of apoptosis and oxidative stress]]> https://www.researchpad.co/article/N8e53f17a-5f83-4fa9-a359-249913deef0c

Abstract

Alpha‐calcitonin gene‐related peptide (α‐CGRP) is a 37‐amino acid neuropeptide that plays an important protective role in modulating cardiovascular diseases. Deletion of the α‐CGRP gene increases the vulnerability of the heart to pressure‐induced heart failure and the administration of a modified α‐CGRP agonist decreases this vulnerability. Systemic administration of α‐CGRP decreases blood pressure in normotensive and hypertensive animals and humans. Here we examined the protective effect of long‐term administration of native α‐CGRP against pressure‐overload heart failure and the likely mechanism(s) of its action. Transverse aortic constriction (TAC) was performed to induce pressure‐overload heart failure in mice. We found that TAC significantly decreased left ventricular (LV) fractional shortening, ejection fraction, and α‐CGRP content, and increased hypertrophy, dilation, and fibrosis compared to sham mice. Administration of α‐CGRP‐filled mini‐osmotic pumps (4 mg/kg bwt/day) in TAC mice preserved cardiac function and LV α‐CGRP levels, and reduced LV hypertrophy, dilation, and fibrosis to levels comparable to sham mice. Additionally, TAC pressure‐overload significantly increased LV apoptosis and oxidative stress compared to the sham mice but these increases were prevented by α‐CGRP administration. α‐CGRP administration in TAC animals decreased LV AMPK phosphorylation levels and the expression of sirt1, both of which are regulatory markers of oxidative stress and energy metabolism. These results demonstrate that native α‐CGRP is protective against pressure‐overload induced heart failure. The mechanism of this cardio‐protection is likely through the prevention of apoptosis and oxidative stress, possibly mediated by sirt1 and AMPK. Thus, α‐CGRP is a potential therapeutic agent in preventing the progression to heart failure, and the cardio‐protective action of α‐CGRP is likely the result of a direct cellular effect; however, a partial vasodilatory blood pressure‐dependent mechanism of α‐CGRP cannot be excluded.

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<![CDATA[Modified HEK cells simulate DCT cells in their sensitivity and response to changes in extracellular K]]> https://www.researchpad.co/article/N98644c7c-a2d5-4963-8fe4-e4ae48bc31b5

Abstract

A potassium (K+) rich diet is known to have an antihypertensive effect that has been embodied by the NHLBI in the DASH diet. However, the molecular basis for this blood pressure‐lowering effect has been unclear, until a recent study proposed a model in which the DCT cells of the kidney regulate their salt transport in response to variations in intracellular chloride ([Cl]i), which are directly regulated by serum K+. With the knowledge that WNK proteins are Cl sensors, and are a part of the WNK/SPAK/NCC signaling cascade which regulates the NCC, the main salt transporter in the distal nephron, we examined the effect of serum K+ on the ([Cl]i) and, in turn its effect on the WNK4 signaling pathway in a “modified HEK 293T” cell line. Using a fluorescence‐based approach in this cell line, we have shown that the membrane potential of the cell membrane is sensitive to the small changes in external KCl within the physiological range (2–5 mM), thus functioning as a K+ electrode. When the extracellular K+ was progressively increased (2–5 mM), the membrane depolarization lead to a subsequent increase in [Cl]i measured by fluorescence quenching of an intracellular chloride sensor. Increase in extracellular [K] resulted in a decrease in the phosphorylation of the WNK4 protein and its downstream targets, SPAK and NCC. This confirms that small changes in serum K can affect WNK4/SPAK/NCC signaling and transcellular Na+ flux through the DCT and provide a possible mechanism by which a K‐rich DASH diet could reduce blood pressure.

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