Differential expression of group I metabotropic glutamate receptors (mGluRs) in the rat pheochromocytoma cell line PC12: Role of nerve growth factor and ras

Glutamate treatment of PC12 cells has been shown to result in the accumulation of intracellular inosltol phosphates suggesting the presence of glutamate metabotropic receptors (mGluRs) positively coupled to phospholipase C. The present study examined the expression of group I rnGluRs (mGluR1 and mGluR5) in PC12 cells. Undifferentiated PC12 cells were found to express both mGluR5 mRNA and receptor protein by reverse transcription polymerase chain reaction (RT-PCR) and western blot techniques. However, mGtuR1 mRNA was not detected in these cells and western blot analysis showed only faint mGluR1α immunoreactivity suggesting a very low level of rnGluR1 expression. Nerve growth factor-induced differentiation of PC12 cells resulted in the induction of rnGluR1α and mGluR1β mRNA and mGluR1α protein. PC12 ceils overexpressing dominant negative ras revealed that NGF-induced mGluR1 induction, but not mGluR5 expression, is dependent on ras pathway activation in these cells. These results suggest PC12 cells may be a useful model for investigating the regulation and expression of group I rnGluR isoforms and their role in neuronal processes in vitro.