Molecular cloning and characterization of the promoter region of the human Phox2b gene.
The closely related homeodomain transcription factors, Phox2a and Phox2b, are restrictively expressed in central and peripheral noradrenergic (NA) neurons in an overlapping but distinct manner, and critically regulate the differentiation and neurotransmitter identity of NA neurons. The structure and function of the human Phox2a (hPhox2a) promoter has recently been reported. Towards the long-term goal of delineating the regulatory cascade of NA neuron differentiation, we isolated a human Phox2b (hPhox2b) genomic clone encompassing approximately 7.8 kb of the 5' upstream promoter region, the entire exon-intron structure and 4.5 kb of the 3' flanking region. Two transcription start sites are identified to reside 115 and 110 nucleotides upstream of the start codon, based on both primer extension and 5'-rapid amplification of the cDNA ends analyses. In addition, transient transfection assays indicate that 1.1 kb or longer upstream sequences of the hPhox2b gene may confer cell type-specific gene expression in certain, but not all cell lines. The promoter activity of the hPhox2b gene is modestly transactivated by forced co-expression of Phox2b and the hPhox2b gene promoter contains a high-affinity binding site at -320 to -295 bp. This study provides a frame to further elucidate the molecular mechanisms underlying the regulation of Phox2a and Phox2b gene expression and its relation to NA differentiation.
Jong Hong
Seok
S
Molecular Neurobiology Laboratory, MRC215, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA.
Chae
Han
H
Kim
Kwang-Soo
KS
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D018398:Homeodomain Proteins; C109220:NBPhox protein; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; D009638:Norepinephrine