Activation of the black seabream (Acanthopagrus schlegeli) somatolactin-alpha gene promoter by Pit-1c in the Hepa-T1 cell-line.
Somatolactin (SL) is a pituitary hormone of the growth hormone (GH) gene family found only in fish. To understand the regulation of this hormone at the level of gene transcription, we obtained a SLalpha gene from black seabream (bsb), with its 5' flanking promoter region carrying several putative transcription factors including seven binding sites for pituitary-specific transcription factor 1 (Pit-1). To study the actions of Pit-1 on this gene promoter, we cloned three variants of bsbPit-1 (Pit-1a, Pit-1b and Pit-1c) derived from alternative splicing of mRNA or differential transcription start sites from black seabream pituitary. The deduced amino acid sequences of these Pit-1s contained 371 amino acids (aa), 333 and 311aa for the three Pit-1 variants, Pit-1a, Pit-1b and Pit-1c, respectively, with diverse regions of Pit-1 located at the transactivation domain. The actions of bsbPit-1 variants on the bsbSL gene promoter were investigated using a co-transfection assay, with a reporter gene using a transient expression assay in Hepa-T1 cells. The N-terminus truncated isoform bsbPit-1c showed the highest level of activity on SLalpha gene promoter activation in Hepa-T1 cells; however, neither Pit-1a nor Pit-1b activated the bsbSL gene promoter in the same study.
Tian
Jing
J
Department of Biochemistry, The Chinese University of Hong Kong, Sha Tin, NT, Hong Kong SAR, China.
Chan
King Ming
KM
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000378:metabolism; D010907:Pituitary Hormones / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000378:metabolism; D021541:Sea Bream; D050817:Transcription Factor Pit-1 / Q000378:metabolism*; D015533:Transcriptional Activation
D029941:Fish Proteins; D006023:Glycoproteins; D010907:Pituitary Hormones; D020033:Protein Isoforms; D050817:Transcription Factor Pit-1; C064448:somatolactin protein, fish