Metastasis-associated Mts1 (S100A4) Protein Modulates Protein Kinase C Phosphorylation of the Heavy Chain of Nonmuscle Myosin

Abstract

Mts1 protein (S100A4 according to a new classification) has been implicated in the formation of the metastatic phenotype via regulation of cell motility and invasiveness. Previously we have demonstrated that Mts1 protein interacted with the heavy chain of nonmuscle myosin in a calcium-dependent manner. To elucidate the role of the Mts1-myosin interaction, we mapped the Mts1-binding region on the myosin heavy chain molecule. We prepared proteolytically digested platelet myosin and a series of overlapped myosin heavy chain protein fragments and used them in a blot overlay with Mts1 protein. Here we report that the Mts1-binding site is located within a 29-amino acid region, at the C-terminal end of the myosin heavy chain (between 1909 -1937 amino acids). Two-dimensional phosphopeptide analysis showed that Mts1 protein inhibits protein kinase C phosphorylation of the platelet myosin heavy chain at Ser-1917. We hypothesize that Mts1 protein regulates cytoskeletal dynamics of the metastatic cells through modulation of the myosin phosphorylation by protein kinase C in calcium-dependent fashion.

Mutually antagonistic actions of S100A4 and S100A1 on normal and metastatic phenotypes

“…More importantly, a completely novel finding is now made that the presence of S100A1 antagonizes a major biological function of S100A4, that of the induction of metastasis in vivo and associated properties in cultured cells. S100A4 interacts with, and inhibits the self-association of rNMMHCIIA (Kriajevska et al, 1994;Ford and Zain, 1995), and it has been suggested that S100A4 affects the phosphorylation of a NMMHCIIA fragment by protein kinase C and casein kinase 2 in vitro (Kriajevska et al, 1998. When tested in vitro, S100A1 significantly and specifically reversed the inhibitory effects of S100A4 on both the self-assembly of a recombinant fragment of NMMHCIIA and its phosphorylation by protein kinase C. S100A1 itself showed no effect on the self-assembly and phosphorylation by PKC of the NMMHCIIA in vitro, suggesting strongly that the effect of S100A1 is not a direct one, but acts by affecting S100A4 function.…”

Extracellular S100A4(mts1) stimulates invasive growth of mouse endothelial cells and modulates MMP-13 matrix metalloproteinase activity

“…A recombinant C-terminal peptide of human myosin heavy chain named Hmyo4-3B (1762-1961 amino acids) was isolated and purified as described (Kriajevska et al, 1998). Human recombinant S100A12 was isolated and purified as described (Mikkelsen et al, 2001).…”

A Genomic and Proteomic Analysis of Activation of the Human Neutrophil by Lipopolysaccharide and Its Mediation by p38 Mitogen-activated Protein Kinase

“…The up-regulation of nonmuscle myosin heavy chain and a putative phosphorylated form of myosin heavy chain (putative protein kinase C substrate by prediction rules) in the LPSexposed PMN (Table IV) is of uncertain significance; myosin has been implicated in multiple functions in the PMN, including locomotion, fluid pinocytosis, and phagocytosis (58). Of interest, however, S100A4 (down-regulated, Table II) has been reported to regulate cytoskeletal dynamics by inhibiting protein kinase C-mediated phosphorylation of nonmuscle myosin heavy chain (59). LPS induction of stathmin phosphorylation (Table IV and Fig.…”