A NEW CYS(2) HIS(2) ZINC-FINGER GENE, RKR2, IS EXPRESSED IN DIFFERENTIATED RAT OLIGODENDROCYTES AND ENCODES PROTEIN WITH A FUNCTIONAL REPRESSOR DOMAIN/

The function of the vertebrate nervous system is dependent on the prop er myelination of its fiber tracts. Myelin of the CNS is produced by o ligodendrocytes. To identify gene regulatory proteins expressed in thi s particular glial cell type, we isolated cDNAs coding for Cys(2)/His( 2) zinc finger proteins from a rat oligodendrocyte cDNA library. One c lone, named rKr2 (rKr for rat Kruppel-type protein), encodes a protein with 19 carboxy-terminal zinc finger domains and an amino-terminal Kr uppel-associated box domain. This amino-terminal domain of the rKr2 pr otein behaved as a strong transcriptional repressor module when fused to the DNA binding domain of yeast GAL4 and tested on an appropriate r eporter construct. High levels of rKr2 mRNA in adult rat tissues were found only in the CNS and testis; in the CNS, the message was predomin antly expressed in differentiated oligodendrocytes. The modular struct ure of the rKr2 protein (carboxy-terminal DNA binding domain, amino-te rminal repressor module) and its expression pattern suggest that it ac ts as a sequence-specific transcriptional repressor in the myelin-prod ucing glial cells of the CNS.