Expression and functional role of mGluR3 and mGluR5 in human astrocytes and glioma cells: opposite regulation of glutamate transporter proteins.

We examined the regulation of glutamate transporter protein expression after stimulation with selective metabotropic glutamate receptor (mGluR) agonists in cultured human glial cells. mGluR3 and mGluR5 are expressed in human astrocytes and in human glioma cells in vivo as well as in vitro, as shown by either RT-PCR or western blot analysis. The selective group I agonist (S)-3,5-dihydroxyphenylglycine produced a significant down-regulation of both GLAST and GLT-1 protein expression in astrocytes cultured in the presence of growth factors.

Expression and distribution of id helix-loop-helix proteins in human astrocytic tumors.

The Id family of helix-loop-helix proteins is involved in a variety of processes, such as development, proliferation, and angiogenesis. In this study, we investigated the expression pattern of Id1, Id2, and Id3 in surgical specimens of human glial tumors. Western blot analysis demonstrated that all three Id proteins were expressed in astrocytic tumors.