EXPRESSION OF A NOVEL MURINE HOMEOBOX GENE IN THE DEVELOPING CEREBELLAR EXTERNAL GRANULAR LAYER DURING ITS PROLIFERATION

The TGIF homeobox gene encodes a homeoprotein that represses the 9-cis retinoic acid receptor-dependent transcription activation. To investi gate the potential role of this gene in vertebrate development, we hav e isolated cDNA clones of the murine TGIF (mTGIF) gene and analyzed it s expression pattern during mouse embryogenesis and postnatal developm ent by Northern analysis, reverse transcriptase-polymerase chain react ion (RT-PCR), and in situ hybridization histochemistry. mTGIF transcri pts were detected at day E16 in the emerging external granular layer ( EGL), the cells of which arise from the proliferating cerebellar neuro epithelium. Expression of mTGIF transcripts was also detected at day E 16 in the proliferating cells in the neuroepithelium of the hippocampa l formation. Following gestation, mTGIF expression increases to a maxi mum between postnatal days 5 and 10 (PN5 and PN10) in the rapidly expa nding cerebellar EGL. mTGIF transcripts are no longer detectable when EGL proliferation ceases on approximately day PN15. Throughout embryo development and in the adult mice, TGIF is detected in a restricted nu mber of tissues, mostly in proliferating and differentiating cell line ages, such as tongue and testis, Our results suggest that the TGIF gen e regulates target genes involved in the proliferation, migration, and /or differentiation of particular neuronal cell lineages in the develo ping brain. (C) 1996 Wiley-Liss, Inc.