Oishika Chatterjee , Jagannath Jana , Suman Panda , Anindya Dutta , Akshay Sharma , Suman Saurav , Rajender K. Motiani , Klaus Weisz , Subhrangsu Chatterjee
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引用次数: 0
Abstract
ORAI1 is an intrinsic component of store-operated calcium entry (SOCE) that strictly regulates Ca2+ influx in most non-excitable cells. ORAI1 is overexpressed in a wide variety of cancers, and its signal transduction has been associated with chemotherapy resistance. There is extensive proteomic interaction of ORAI1 with other channels and effectors, resulting in various altered phenotypes. However, the transcription regulation of ORAI1 is not well understood. We have found a putative G-quadruplex (G4) motif, ORAI1-Pu, in the upstream promoter region of the gene, having regulatory functions. High-resolution 3-D NMR structure elucidation suggests that ORAI1-Pu is a stable parallel-stranded G4, having a long 8-nt loop imparting dynamics without affecting the structural stability. The protruded loop further houses an E-box motif that provides a docking site for transcription factors like Zeb1. The G4 structure was also endogenously observed using Chromatin Immunoprecipitation (ChIP) with anti-G4 antibody (BG4) in the MDA-MB-231 cell line overexpressing ORAI1. Ligand-mediated stabilization suggested that the stabilized G4 represses transcription in cancer cell line MDA-MB-231. Downregulation of transcription further led to decreased Ca2+ entry by the SOCE pathway, as observed by live-cell Fura-2 Ca2+ imaging.
期刊介绍:
Cell Calcium covers the field of calcium metabolism and signalling in living systems, from aspects including inorganic chemistry, physiology, molecular biology and pathology. Topic themes include:
Roles of calcium in regulating cellular events such as apoptosis, necrosis and organelle remodelling
Influence of calcium regulation in affecting health and disease outcomes