Developmental and functional evidence of a role for Zfhep in neural cell development

The rat Zfhep gene encodes a member of the Zfh family of transcription factors having a homeodomain-like sequence and multiple zinc fingers. We examined expression of Zfhep in the rat forebrain during embryonic and postnatal development. Zfhep mRNA was strongly expressed in the progenitor cells of the ventricular zone around the lateral ventricles on E14 and E16, but showed little expression in cells that had migrated to form the developing cortex. Dual labeling with PCNA demonstrated expression of Zfhep mRNA in proliferating cells. Expression of Zfhep in the ventricular zone decreases during late development as the population of progenitor cells decreases. This pattern is distinctly different from other members of the Zfh family. We also examined the expression of Zfhep protein during retinoic acid-induced neurogenesis of P19 embryonal carcinoma cells. Zfhep is highly expressed in P19 neuroblasts, and expression decreases by the time of morphological neurogenesis. Hence, both P19 cells and embryonic brain demonstrate a loss of Zfhep expression during the transition from proliferating precursor to differentiated neural cells. We investigated a possible link between Zfhep and proliferation by treating human glial cell lines with Zfhep antisense phosphorothioate oligodeoxynucleotides. Two Zfhep antisense oligonucleotides repressed proliferation of either U-138 or U-343 glioblastoma cells more than control oligonucleotides. Based on the expression patterns of Zfhep in vivo and in the P19 cell model of neurogenesis, we suggest that Zfhep may play a role in proliferation or differentiation of neural cells.