Characterization of MRCK(a) Autophosphorylation and its Role in the Actomyosin Cytoskeleton Complex

Non-muscle myosin II (NMII) is regulated by phosphorylation of its regulatory light chain (MLC) at T18/S19. We found that serine/threonine kinase MRCK(a) phospho-sites S1609, S1611, S1632 and S1635 act as potential autoregulators of MRCK(a) that increase or decrease MLC phosphorylation. Moreover, we report the use of BioID on MLC T18/S19 phosphomimetic and dephosphorylation states using HEK293T-RExTM stable cells. The data gathered consisted of interacting partners showing differences in phosphomimetic and dephosphorylation states of MLC. 2 of these hits were cytoskeletal proteins that had high phosphorylation ratios: nucleotide diphosphate kinase 1 (NME1) and FLII actin remodeling protein (FLII). It’s possible that both FLII and NME1 interact with each other in order to impact cancer metastasis, demonstrating the need to research these candidates further. Ultimately, our research demonstrates the importance of NMII regulation on cellular migration, which in turn affects cancer metastatic cells.