Nerve growth factor induces rapid accumulation of the GTP-bound form of p21ras in rat pheochromocytoma PC12 cells.
The ras gene product (p21) is thought to transduce signals from various growth and differentiation factors. p21 is a GTP-binding protein, and its activity is regulated by the bound GDP/GTP ratio. We analysed p21-bound nucleotides in cell lysates of rat pheochromocytoma cell line PC12 cells stimulated with various factors. Nerve growth factors (NGF) rapidly increased the relative amount of active p21-GTP complex to as much as 20% of the total amount of p21 within 2 min. The amount of p21-GTP then declined to 8% after 10 min, and this level was sustained for at least 2 h. Epidermal growth factor (EGF) also stimulated a rapid accumulation of p21-GTP to the same extent as seen with NGF, but the amount of p21-GTP declined to 5% after 10 min and gradually returned to the basal level within 60 min. In contrast, basic fibroblast growth factor, interleukin 6 and dibutyryl cAMP, which induce neuronal differentiation of PC12 cells, did not stimulate the accumulation of p21-GTP at any time point examined. Phorbol 12-myristate 13-acetate also had no effect. Interestingly, the protein kinase inhibitor K-252a specifically suppressed the NGF-induced accumulation of p21-GTP, but did not suppress the EGF-induced response. These results strongly suggest that an active p21-GTP complex transduces the differentiation signal from NGF. It may also be suggested that the process of activating p21 is mediated by a K-252a-sensitive protein kinase(s).
Muroya
K
K
Division of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.
Hattori
S
S
Nakamura
S
S
D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D066298:In Vitro Techniques; D026121:Indole Alkaloids; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016716:PC12 Cells; D047428:Protein Kinase Inhibitors; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
D002227:Carbazoles; D026121:Indole Alkaloids; D009414:Nerve Growth Factors; D047428:Protein Kinase Inhibitors; D004815:Epidermal Growth Factor; D006160:Guanosine Triphosphate; C049985:staurosporine aglycone; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras)