Cell-cycle regulated expression and serine phosphorylation of the myristylated protein kinase C substrate, SSeCKS: Correlation with culture confluency, cell cycle phase and serum response

摘要: We recently identified a novel myristylated protein kinase C (PKC) substrate, named SSeCKS (pronounced essex), whose transcription is suppressed >15 fold in src- or ras-transformed rodent fibroblasts, but not raf-transformed cells [1, 2]. associates with and controls the elaboration of cortical cytoskeletal matrix response to phorbol esters [2], overexpression causes growth arrest untransformed NIH3T3 [3]. Our preliminary data suggested that functions as negative mitogenic regulator by controlling architecture serine phosphorylation kinases such PKC alters its interaction matrices ability control mitogenesis. Here, we determine effects culture confluency, serum on steady-state abundance RNA relative level phosphoserine-free SSeCKS. initially induced factors cont act-inhibited rather than cell-cycle starvation, hydroxyurea nocodazole, following serum-induced G1/S progression, suppressed. hyperphosphorylated residues during progression G2/M phase. Finally, show induction expression contact inhibition independent SSeCKS' responsiveness. These suggest function can be controlled at either transcriptional post-translational confluency. The strengthen notion plays an important, yet transient, role cell cycle from G0 G1 differs contact-inhibited growth. (Mol Cell Biochem 175: 233–241, 1997)