Protein Kinase C α-mediated Negative Feedback Regulation Is Responsible for the Termination of Insulin-like Growth Factor I-induced Activation of Nuclear Phospholipase C β1 in Swiss 3T3 Cells
| Autor: | R. Stewart Gilmour, Lance Yi Xu, Yu Wang, Aimin Xu |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Protein Kinase C-alpha
PKC Phosphorylation Site Phospholipase C beta Biology Biochemistry Feedback Mice chemistry.chemical_compound Phosphoinositide phospholipase C Serine Animals Enzyme Inhibitors Insulin-Like Growth Factor I Molecular Biology Protein Kinase C Protein kinase C DNA Primers Diacylglycerol kinase Cell Nucleus Base Sequence Phospholipase C Cell growth Inositol trisphosphate 3T3 Cells Cell Biology Cell biology Enzyme Activation Isoenzymes chemistry Type C Phospholipases Mutagenesis Site-Directed Phosphorylation |
| Zdroj: | Journal of Biological Chemistry. 276:14980-14986 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m009144200 |
| Popis: | Previous studies from several independent laboratories have demonstrated the existence of an autonomous phosphoinositide (PI) cycle within the nucleus, where it is involved in both cell proliferation and differentiation. Stimulation of Swiss 3T3 cells with insulin-like growth factor-I (IGF-I) has been shown to induce a transient and rapid increase in the activity of nuclear-localized phospholipase C (PLC) beta1, which in turn leads to the production of inositol trisphosphate and diacylglycerol in the nucleus. Nuclear diacylglycerol provides the driving force for the nuclear translocation of protein kinase C (PKC) alpha. Here, we report that treatment of Swiss 3T3 cells with Go6976, a selective inhibitor of PKC alpha, caused a sustained elevation of IGF-I-stimulated nuclear PLC activity. A time course study revealed an inverse relationship between nuclear PKC activity and the activity of nuclear PLC in IGF-I-treated cells. A time-dependent association between PKC alpha and PLC beta1 in the nucleus was also observed following IGF-I treatment. Two-dimensional phosphopeptide mapping and site-directed mutagenesis demonstrated that PKC promoted phosphorylation of PLC beta1 at serine 887 in the nucleus of IGF-I-treated cells. Overexpression of either a PLC beta1 mutant in which the PKC phosphorylation site Ser(887) was replaced by alanine, or a dominant-negative PKC alpha, resulted in a sustained activation of nuclear PLC following IGF-I stimulation. These results indicate that a negative feedback regulation of PLC beta1 by PKC alpha plays a critical role in the termination of the IGF-I-dependent signal that activates the nuclear PI cycle. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|