title: Retinoic acid activates human secretin gene expression by Sp proteins and nuclear factor I in neuronal SH-SY5Y cells.
abstract: Secretin is a neuropeptide that is expressed in distinct central neurones. As there is no information on how the secretin gene is regulated in neuronal cells, a well established neuronal differentiation cell model, SH-SY5Y, was used to study transcriptional regulation of the human secretin gene. High secretin transcript and peptide levels were found in this cell, and secretin gene expression and promoter activity were up-regulated upon all-trans retinoic acid (RA) treatment. Within the promoter, a functional GC-box 1 (-131 from ATG, relative to the ATG initiation codon) was found to be regulated by a brain-specific Sp protein, Sp4, and ubiquitous factors Sp1 and Sp3. The human secretin gene in SH-SY5Y cells is controlled by the (Sp1 + Sp4)/Sp3 ratio and the RA-induced activation is a partial result of a decrease in Sp3 levels. In addition to the GC-box 1, an N1 motif in close proximity was also responsible for RA-induced secretin gene activation. Competitive gel mobility shift and southwestern blot studies revealed binding of Nuclear Factor I (NFI) with the N1 motif. Overexpression of NFI-C increased promoter activity upon RA treatment. Consistent with this observation, NFI-C transcript levels were augmented after RA treatment. We conclude that RA induction of the secretin gene in neuronal cells is regulated by the combined actions of reducing Sp3 and increasing NFI-C expression.
authors.affiliation: Department of Zoology, The University of Hong Kong, Hong Kong, China.
authors.forename: Leo Tsz-On
authors.initials: LT
authors.lastname: Lee
authors.forename: Kian-Cheng
authors.initials: KC
authors.lastname: Tan-Un
authors.forename: Marie Chia-Mi
authors.initials: MC
authors.lastname: Lin
authors.forename: Billy Kwok-Chong
authors.initials: BK
authors.lastname: Chow
mesh_terms: D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D020218:Response Elements / Q000187:drug effects; D012633:Secretin / Q000096:biosynthesis* / Q000235:genetics*; D016329:Sp1 Transcription Factor / Q000502:physiology*; D051705:Sp3 Transcription Factor; D051706:Sp4 Transcription Factor; D014157:Transcription Factors / Q000502:physiology*; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D051839:NFI Transcription Factors; C497647:NFIC protein, human; C497121:SP3 protein, human; C497124:SP4 protein, human; D016329:Sp1 Transcription Factor; D051706:Sp4 Transcription Factor; D014157:Transcription Factors; D012633:Secretin; D051705:Sp3 Transcription Factor; D014212:Tretinoin