NEURONAL DEPENDENCY OF THE GLYCINE TRANSPORTER GLYT1 EXPRESSION IN GLIAL-CELLS

Two membrane-localized transporter proteins (GLYT1 and GLYT2) are resp onsible for removal of extracellular glycine in the mammalian CNS. Whe reas GLYT1 seems to be expressed mainly in glial cells, GLYT2 is neuro nal. The highest concentrations of both transporters are found in glyc inergic areas of the nervous system. The expression of these proteins may be under regulatory control. We demonstrate here that GLYT1 is not expressed in pure glial cultures, but it is expressed by diverse type s of glial cells in mixed neuronal/glial cultures. In these mixed cult ures, the glial expression of GLYT1 is down-regulated after selective elimination of the neurons. The absence of expression in pure glial cu ltures and the observed reduction in the GLYT1 expression after neuron al loss support the existence of a regulatory cross-talk between neuro ns and glia to initiate and sustain the glial expression of GLYT1. (C) 1997 Wiley-Liss, Inc.