VANADIUM SALTS STIMULATE MITOGEN-ACTIVATED PROTEIN (MAP) KINASES AND RIBOSOMAL S6 KINASES

Effect of several vanadium salts, sodium orthovanadate, vanadyl sulfat e and sodium metavanadate on protein tyrosine phosphorylation and seri ne/threonine kinases in chinese hamster ovary (CHO) cells overexpressi ng a normal human insulin receptor was examined. All the compounds sti mulated protein tyrosine phosphorylation of two major proteins with mo lecular masses of 42 kDa (p42) and 44 kDa (p44). The phosphorylation o f p42 and p44 was associated with an activation of mitogen activated p rotein (MAP) kinase as well as increased protein tyrosine phosphorylat ion of p42(mapk) and p44(mapk). Vanadium salts also activated the 90 k Da ribosomal s6 kinase (p90(rsk)) and 70 kDa ribosomal s6 kinase (p70( s6k)). Among the three vanadium salts tested, vanadyl sulfate appeared to be slightly more potent than others in stimulating MAP kinases and p70(s6k) activity. It is suggested that vanadium-induced activation o f MAP kinases and ribosomal s6 kinases may be one of the mechanisms by which insulin like effects of this trace element are mediated.