Browsing by Author "Shenoy, Sudha K"

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    beta-arrestin-1 competitively inhibits insulin-induced ubiquitination and degradation of insulin receptor substrate 1.
    (Mol Cell Biol, 2004-10) Usui, Isao; Imamura, Takeshi; Huang, Jie; Satoh, Hiroaki; Shenoy, Sudha K; Lefkowitz, Robert J; Hupfeld, Christopher J; Olefsky, Jerrold M
    beta-arrestin-1 is an adaptor protein that mediates agonist-dependent internalization and desensitization of G-protein-coupled receptors (GPCRs) and also participates in the process of heterologous desensitization between receptor tyrosine kinases and GPCR signaling. In the present study, we determined whether beta-arrestin-1 is involved in insulin-induced insulin receptor substrate 1 (IRS-1) degradation. Overexpression of wild-type (WT) beta-arrestin-1 attenuated insulin-induced degradation of IRS-1, leading to increased insulin signaling downstream of IRS-1. When endogenous beta-arrestin-1 was knocked down by transfection of beta-arrestin-1 small interfering RNA, insulin-induced IRS-1 degradation was enhanced. Insulin stimulated the association of IRS-1 and Mdm2, an E3 ubiquitin ligase, and this association was inhibited to overexpression of WT beta-arrestin-1, which led by decreased ubiquitin content of IRS-1, suggesting that both beta-arrestin-1 and IRS-1 competitively bind to Mdm2. In summary, we have found the following: (i) beta-arrestin-1 can alter insulin signaling by inhibiting insulin-induced proteasomal degradation of IRS-1; (ii) beta-arrestin-1 decreases the rate of ubiquitination of IRS-1 by competitively binding to endogenous Mdm2, an E3 ligase that can ubiquitinate IRS-1; (iii) dephosphorylation of S412 on beta-arrestin and the amino terminus of beta-arrestin-1 are required for this effect of beta-arrestin on IRS-1 degradation; and (iv) inhibition of beta-arrestin-1 leads to enhanced IRS-1 degradation and accentuated cellular insulin resistance.
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    Independent beta-arrestin 2 and G protein-mediated pathways for angiotensin II activation of extracellular signal-regulated kinases 1 and 2.
    (Proc Natl Acad Sci U S A, 2003-09-16) Wei, Huijun; Ahn, Seungkirl; Shenoy, Sudha K; Karnik, Sadashiva S; Hunyady, László; Luttrell, Louis M; Lefkowitz, Robert J
    Stimulation of a mutant angiotensin type 1A receptor (DRY/AAY) with angiotensin II (Ang II) or of a wild-type receptor with an Ang II analog ([sarcosine1,Ile4,Ile8]Ang II) fails to activate classical heterotrimeric G protein signaling but does lead to recruitment of beta-arrestin 2-GFP and activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) (maximum stimulation approximately 50% of wild type). This G protein-independent activation of mitogen-activated protein kinase is abolished by depletion of cellular beta-arrestin 2 but is unaffected by the PKC inhibitor Ro-31-8425. In parallel, stimulation of the wild-type angiotensin type 1A receptor with Ang II robustly stimulates ERK1/2 activation with approximately 60% of the response blocked by the PKC inhibitor (G protein dependent) and the rest of the response blocked by depletion of cellular beta-arrestin 2 by small interfering RNA (beta-arrestin dependent). These findings imply the existence of independent G protein- and beta-arrestin 2-mediated pathways leading to ERK1/2 activation and the existence of distinct "active" conformations of a seven-membrane-spanning receptor coupled to each.
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    Interleukin-9 mediates chronic kidney disease-dependent vein graft disease: a role for mast cells.
    (Cardiovasc Res, 2017-11-01) Zhang, Lisheng; Wu, Jiao-Hui; Otto, James C; Gurley, Susan B; Hauser, Elizabeth R; Shenoy, Sudha K; Nagi, Karim; Brian, Leigh; Wertman, Virginia; Mattocks, Natalie; Lawson, Jeffrey H; Freedman, Neil J
    Aims: Chronic kidney disease (CKD) is a powerful independent risk factor for cardiovascular events, including vein graft failure. Because CKD impairs the clearance of small proteins, we tested the hypothesis that CKD exacerbates vein graft disease by elevating serum levels of critical cytokines that promote vein graft neointimal hyperplasia. Methods and results: We modelled CKD in C57BL/6 mice with 5/6ths nephrectomy, which reduced glomerular filtration rate by 60%, and we modelled vein grafting with inferior-vena-cava-to-carotid interposition grafting. CKD increased vein graft neointimal hyperplasia four-fold, decreased vein graft re-endothelialization two-fold, and increased serum levels of interleukin-9 (IL-9) five-fold. By quantitative immunofluorescence and histochemical staining, vein grafts from CKD mice demonstrated a ∼two-fold higher prevalence of mast cells, and a six-fold higher prevalence of activated mast cells. Concordantly, vein grafts from CKD mice showed higher levels of TNF and NFκB activation, as judged by phosphorylation of NFκB p65 on Ser536 and by expression of VCAM-1. Arteriovenous fistula veins from humans with CKD also showed up-regulation of mast cells and IL-9. Treating CKD mice with IL-9-neutralizing IgG reduced vein graft neointimal area four-fold, increased vein graft re-endothelialization ∼two-fold, and reduced vein graft total and activated mast cell levels two- and four-fold, respectively. Treating CKD mice with the mast cell stabilizer cromolyn reduced neointimal hyperplasia and increased re-endothelialization in vein grafts. In vitro, IL-9 promoted endothelial cell apoptosis but had no effect on smooth muscle cell proliferation. Conclusion: CKD aggravates vein graft disease through mechanisms involving IL-9 and mast cell activation.
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    Microgravity induces proteomics changes involved in endoplasmic reticulum stress and mitochondrial protection.
    (Scientific reports, 2016-09-27) Feger, Bryan J; Thompson, J Will; Dubois, Laura G; Kommaddi, Reddy P; Foster, Matthew W; Mishra, Rajashree; Shenoy, Sudha K; Shibata, Yoichiro; Kidane, Yared H; Moseley, M Arthur; Carnell, Lisa S; Bowles, Dawn E
    On Earth, biological systems have evolved in response to environmental stressors, interactions dictated by physical forces that include gravity. The absence of gravity is an extreme stressor and the impact of its absence on biological systems is ill-defined. Astronauts who have spent extended time under conditions of minimal gravity (microgravity) experience an array of biological alterations, including perturbations in cardiovascular function. We hypothesized that physiological perturbations in cardiac function in microgravity may be a consequence of alterations in molecular and organellar dynamics within the cellular milieu of cardiomyocytes. We used a combination of mass spectrometry-based approaches to compare the relative abundance and turnover rates of 848 and 196 proteins, respectively, in rat neonatal cardiomyocytes exposed to simulated microgravity or normal gravity. Gene functional enrichment analysis of these data suggested that the protein content and function of the mitochondria, ribosomes, and endoplasmic reticulum were differentially modulated in microgravity. We confirmed experimentally that in microgravity protein synthesis was decreased while apoptosis, cell viability, and protein degradation were largely unaffected. These data support our conclusion that in microgravity cardiomyocytes attempt to maintain mitochondrial homeostasis at the expense of protein synthesis. The overall response to this stress may culminate in cardiac muscle atrophy.
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    Trafficking of G protein-coupled receptors.
    (Circ Res, 2006-09-15) Drake, Matthew T; Shenoy, Sudha K; Lefkowitz, Robert J
    G protein-coupled receptors (GPCRs) play an integral role in the signal transduction of an enormous array of biological phenomena, thereby serving to modulate at a molecular level almost all components of human biology. This role is nowhere more evident than in cardiovascular biology, where GPCRs regulate such core measures of cardiovascular function as heart rate, contractility, and vascular tone. GPCR/ligand interaction initiates signal transduction cascades, and requires the presence of the receptor at the plasma membrane. Plasma membrane localization is in turn a function of the delivery of a receptor to and removal from the cell surface, a concept defined most broadly as receptor trafficking. This review illuminates our current view of GPCR trafficking, particularly within the cardiovascular system, as well as highlights the recent and provocative finding that components of the GPCR trafficking machinery can facilitate GPCR signaling independent of G protein activation.