ROLE OF POU-DOMAIN GENES DURING XENOPUS LAEVIS EMBRYOGENESIS

含有POU结构域序列的转录因子(在

Transcription factors containing the POU domain sequence (found in the genes Pit-1, Oct-1 and 2, and unc-86) may act as regulators of tissue-specific gene expression during embryonic development. Little is known about the early specification of pituitary and neural tissue. To study these developmental processes, we have cloned at least four different POU domain genes from Xenopus laevis. Degenerate oligonucleotides representing all possible codons for two conserved 7 amino acid regions (IKLGYTQ and WFCNRRQ) flanking the POU domain were used as primers in the polymerase chain reaction (PCR). The cDNA derived from adult pituitary and brain poly A+ mRNA served as a template for the PCR. Sequence analysis of one clone derived from pituitary cDNA (XPOU-2) showed 96% homology with the rat Pit 1 ene within the POU-domain region. XPOU-2 is a single copy gene and its transcript (approximately 4.5 KB) is found only in pituitary. We have sequenced at least 3 different POU-containing cDNA's from brain (XPOU-1, 3, and 4). All of these genes are expressed in early Xenopus embryos as well as in brain. The XPOU-1 transcripts (2.5 KB, 3.0 KB) appear to be localized in the head/dorsal region of a tailbud embryo. The smaller transcript of XPOU-1 is also present in adult skin. A partial cDNA sequence of XPOU-1 shows no homology outside the POU-domain. Antipeptide antibodies directed against the deduced amino acid sequence of XPOU-1 are currently being pursued and should be useful for examining the expression of the XPOU-1 protein.