Genomic structure and functional characterization of NBPhox (PMX2B), a homeodomain protein specific to catecholaminergic cells that is involved in second messenger-mediated transcriptional activation.
Homeodomain proteins play essential roles in basic processes during embryogenesis and development. NBPhox, a vertebrate paired-like homeodomain protein specific to catecholaminergic cells, may have a fundamental role in determining and maintaining the catecholaminergic phenotype. Here we describe the human and mouse genomic structures and the functional characterization of NBPhox. The genomic structure of NBPhox is highly conserved at the nucleotide level between human and mouse and is also quite similar to that of other paired-like homeodomain proteins, Arix/Phox2a, CRX, OTX1, and OTX2. The human NBPhox gene (HGMW-approved symbol PMX2B) maps to chromosomal region 5p12-p13. When the NBPhox expression plasmid was introduced into PC12h cells, the transcription from the promoter of the dopamine beta-hydroxylase (DBH) gene was slightly stimulated. However, NBPhox substantially enhances second messenger-mediated activation of the DBH promoter by forskolin and/or phorbol ester. Furthermore, we found that NBPhox can also enhance second messenger-mediated activation of the c-fos promoter and several enhancers, including cyclic AMP-response element, the binding site for activator protein 1, and serum-response element. Our findings provide strong evidence that a homeodomain protein is involved in the activation of several genetic regulatory elements responsive to second messenger-mediated signals. These data suggest that this family of proteins may be involved in determining and maintaining a cell-specific phenotype through regulation of certain genes responsive to second messenger-mediated signals.
Pharmaceutical Frontier Research Laboratories, Japan Tobacco, Inc., 13-2, Fukuura 1-chome, Kanazawa-ku, Yokohama, Kanagawa, 236, Japan. masahiro.yokoyama@ims.jti.co.jp
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002395:Catecholamines / Q000378:metabolism*; D002874:Chromosome Mapping; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004299:Dopamine beta-Hydroxylase / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005091:Exons; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051857:Otx Transcription Factors; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics; D015290:Second Messenger Systems / Q000502:physiology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D002395:Catecholamines; D018076:DNA, Complementary; D018398:Homeodomain Proteins; C109220:NBPhox protein; D009419:Nerve Tissue Proteins; C497655:OTX1 protein, human; C497659:OTX2 protein, human; D051857:Otx Transcription Factors; C497656:Otx1 protein, mouse; C497660:Otx2 protein, mouse; C491061:PHOX2A protein, human; C491060:Phox2a protein, mouse; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C109288:cone rod homeobox protein; D004247:DNA; D004299:Dopamine beta-Hydroxylase