Receptor tyrosine phosphatase zeta/beta in astrocyte progenitors in the developing chick spinal cord

We cloned a cDNA encoding the receptor-type protein tyrosine phosphatase zeta/beta (RPTPZ/beta) from embryonic chick spinal cord. RPTPZ/beta was expressed throughout the ventricular zone (VZ) of the developing spinal cord and in scattered cells outside the VZ. Platelet-derived growth factor receptor alpha (PDGFRa)-positive oligodendrocyte progenitors co-expressed RPTPZ/beta within the VZ but down-regulated RPTPZ/beta after leaving the VZ. Most RPTPZ/beta-positive cells outside the VZ co-expressed glutamine synthetase and fibroblast growth factor receptor-3, indicating that they are astrocyte progenitors. Northern blot analysis revealed a single approximately 9 kbp RPTPZ/beta transcript expressed in the embryonic chick spinal cord, indicating that the shorter alternative-splice products of RPTPZ/beta found in rodent spinal cord and brain--including the abundant extracellular proteoglycan known as phosphacan--are not present in the embryonic chick spinal cord.