Cloning and expression analysis of YY1AP-related protein in the rat brain.

YY1AP-related protein (YARP) is a structural homolog of YY1AP, a transcriptional coactivator of the multifunctional transcription factor YY1. We cloned a rat YARP cDNA that encoded a 2256 amino acid protein with 93% homology to the human counterpart. Northern blots revealed significant expression of the YARP gene in the rat brain. In situ hybridization demonstrated its expression in neurons throughout the brain, including pyramidal cells in the cerebral cortex and hippocampus and granule cells in the dentate gyrus. YARP was coexpressed with YY1 in these same neuronal cells. However, there was no evidence of YARP expression in glia. In the developing rat brain, the level of YARP mRNA ( approximately 10 kb) peaked at embryonic day 18 and promptly declined thereafter to reach the steady-state level found in adulthood, by 14 days after birth. These results suggest that YARP functions at a late stage of neurogenesis during perinatal development of the rat brain, as well as in mature neurons.