A novel, non-canonical mechanism of regulation of MST3 (mammalian Sterile20-related kinase 3)

Fuller, S. J., McGuffin, L. J. ORCID: https://orcid.org/0000-0003-4501-4767, Marshall, A. K., Giraldo, A., Pikkarainen, S., Clerk, A. ORCID: https://orcid.org/0000-0002-5658-0708 and Sugden, P. (2012) A novel, non-canonical mechanism of regulation of MST3 (mammalian Sterile20-related kinase 3). Biochemical Journal, 442 (3). pp. 595-610. ISSN 0264-6021 doi: 10.1042/BJ20112000

Abstract/Summary

The canonical pathway of regulation of the germinal centre kinase (GCK) III subgroup member, mammalian Sterile20-related kinase 3 (MST3), involves a caspase-mediated cleavage between N-terminal catalytic and C-terminal regulatory domains with possible concurrent autophosphorylation of the activation loop MST3(Thr178-), induction of Ser-/Thr-protein kinase activity and nuclear localisation. We identified an alternative ‘non-canonical’ pathway of MST3 activation (regulated primarily through dephosphorylation) which may also be applicable to other GCKIII (and GCKVI) subgroup members. In the basal state, inactive MST3 co-immunoprecipitated with the Golgi protein, GOLGA2/gm130. Activation of MST3 by calyculin A (a protein Ser-/Thr- phosphatase 1/2A inhibitor) stimulated (auto)phosphorylation of MST3(Thr178-) in the catalytic domain with essentially simultaneous cis-autophosphorylation of MST3(Thr328-) in the regulatory domain, an event also requiring the MST3(341-376) sequence which acts as a putative docking domain. MST3(Thr178-) phosphorylation increased MST3 kinase activity but this activity was independent of MST3(Thr328-) phosphorylation. Interestingly, MST3(Thr328-) lies immediately C-terminal to a STRAD pseudokinase-like site recently identified as being involved in binding of GCKIII/GCKVI members to MO25 scaffolding proteins. MST3(Thr178- /Thr328-) phosphorylation was concurrent with dissociation of MST3 from GOLGA2/gm130 and association of MST3 with MO25, and MST3(Thr328-) phosphorylation was necessary for formation of the activated MST3-MO25 holocomplex.

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URI	https://reading-clone.eprints-hosting.org/id/eprint/26012
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Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Biomedical Sciences
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Publisher	Portland Press Limited
Publisher Statement	The final version of record is available at http://www.biochemj.org/bj
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