GSK3β phosphorylates Six1 transcription factor and regulates its APC/C Cdh1 mediated proteosomal degradation.

Autor: Rafiq A; Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India., Aashaq S; Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India; Department of Immunology and Molecular Medicine, SKIMS, Srinagar 190011, India., Jan I; Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India., Ali M; Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India., Rakshan R; Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India., Bashir A; Faculty of Biology, Fatima College of Health Sciences, Al-Raqaib 2, Ajman 3798, United Arab Emirates., Haq E; Department of Biotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India., Beigh MA; Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India. Electronic address: beighm@uok.edu.in.
Jazyk: angličtina
Zdroj: Cellular signalling [Cell Signal] 2024 Mar; Vol. 115, pp. 111030. Date of Electronic Publication: 2023 Dec 30.
DOI: 10.1016/j.cellsig.2023.111030
Abstrakt: Sine oculis homeobox homolog 1 (Six1) is a developmentally important transcription factor that regulates cellular proliferation, apoptosis, and dissemination during embryogenesis. Six1 overexpression as reported in multiple cancers modulates expression of a repertoire of its target genes causing an increase in proliferation, metastasis and survival of cancer cells. Six1 exists as a cell cycle regulated nuclear phosphoprotein and its cellular turnover is regulated by APC/C (Anaphase promoting complex / Cyclosome) complex mediated proteolysis. However, the kinases that regulate Six1 proteolysis have not been identified and the mechanistic details that cause its overproduction in various cancers are lacking. Here, we report that Six1 is a physiological GSK3β substrate. GSK3β interacts with Six1 and phosphorylates it at Ser 221 within the conserved consensus sequence in its carboxy terminus. Using pharmacological inhibition, siRNA mediated knockdown and protein overexpression of GSK3β; we show that GSK3β regulates Six1 protein stability. Pulse chase analysis of Six1 revealed that GSK3β regulates its ubiquitin proteolysis such that Six1 phosphomimicking mutant (Six1 S221E ) for Ser 221 site had dramatically increased half-life than its phosphodeficient (Six1 S221A ) and wild type variants. Furthermore, we demonstrate that GSK3β rescues Six1 from APC dependent proteolysis by regulating its binding with APC/C co-activator protein Cdh1. Importantly, strong positive correlation exists between GSK3β and Six1 protein levels throughout the cell cycle and in multiple cancers indicating that GSK3β activation may in part contribute to Six1 overproduction in a subset of human cancers.
Competing Interests: Declaration of competing interest The authors declare that there are no competing interests involved in this study.
(Copyright © 2023 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: