Rabbit Anti-Human GSKIP Polyclonal antibody

GSK3 beta interacting protein (GSKIP) is a naturally occurring negative regulator of GSK3 beta and retains both the Protein Kinase A Regulatory subunit binding (PKA-RII) domain and GSK3 beta interacting domain. Of these two domains, we found that PKA-RII is required for forming a working complex comprising PKA/GSKIP/GSK3 beta/Drpl to influence phosphorylation of Drpl Ser637. In this study, bioinformatics and experimental explorations re-analyzing GSKIP's biofunctions suggest that the evolutionarily conserved Domain of Unknown Function (DUF727) is an ancestral prototype of GSKIP in prokaryotes, and acquired the C-terminal GSK3 beta binding site (tail) in invertebrates except for Saccharomyces spp., after which the N-terminal PKA-RII binding region (head) evolved in vertebrates. These two regions mutually influence each other and modulate GSKIP binding to GSK3 beta in yeast two-hybrid assays and co-immunoprecipitation. Molecular modeling showed that mammalian GSKIP could form a dimer through the L130 residue (GSK3 beta binding site) rather than V41/L45 residues. In contrast, V41/L45P mutant facilitated a gain-of-function effect on GSKIP dimerization, further influencing binding behavior to GSK3 beta compared to GSKIP wild-type (wt). The V41/L45 residues are not only responsible for PKA RII binding that controls GSK3 beta activity, but also affect dimerization of GSKIP monomer, with net results of gain-of function in GSKIP-GSK3 beta interaction. In addition to its reported role in modulating Drpl, Ser637 phosphorylation caused mitochondrial elongation; we postulated that GSKIP might be involved in the Wnt signaling pathway as a scavenger to recruit GSK3 beta away from the p-catenin destruction complex and as a competitor to compete for GSK3 beta binding, resulting in accumulation of 5675 phosphorylated P-catenin.

Glycogen synthase kinase (GSK)-3 beta interaction protein (GSKIP), a key regulator of signaling transduction, is implicated in multiple pathological processes. However, whether GSKIP is involved in myocardial infarction is unknown. The present study was designed to determine the potential involvement of GSKIP in myocardial hypoxia/reoxygenation (H/R) injury, as an in vitro model for the study of myocardial infarction. Our data showed that H/R treatment triggered a marked decrease in GSKIP expression in cardiomyocytes. The upregulation of GSKIP significantly rescued the decreased viability of H/R-exposed cardiomyocytes and attenuated H/R-induced apoptosis and reactive oxygen species (ROS) generation. On the contrary, the depletion of GSKIP enhanced the sensitivity of cardiomyocytes to H/R-induced injury. Further data exhibited that GSKIP overexpression upregulated the nuclear expression of nuclear factorerythroid-derived 2-related factor 2 (Nrf2) and increased Nrf2/antioxidant response element (ARE)mediated transcription activity associated with upregulation of GSK-3 beta phosphorylation. Interestingly, inhibition of GSK-3 beta by a chemical inhibitor markedly enhanced Nrf2/ARE activation and abrogated GSKIP depletion-exacerbated sensitivity to H/R-induced injury. In addition, Nrf2 inhibition markedly reversed GSKIP overexpression-induced cardioprotective effect against H/R injury. Overall, these results demonstrate that overexpression of GSKIP alleviates H/R-induced apoptosis and oxidative stress in cardiomyocytes by enhancing Nrf2/ARE antioxidant signaling via GSK-3 beta inhibition. Our study indicates a potential role of GSKIP in myocardial infarction and GSKIP may serve as a promising molecular target for card ioprotection. (C) 2020 Elsevier Inc. All rights reserved.