Cloning of the rat Slc14a2 gene and genomic organization of the UT-A urea transporter

Yushi Nakayama, Masahiro Naruse, Alexander Karakashian, Tao Peng, Jeff M. Sands, Serena M. Bagnasco

Research output: Contribution to journalArticlepeer-review

Abstract

We cloned the Slc14a2 gene and determined the genomic organization of the rat urea transporter UT-A. Slc14a2, the gene encoding the rat UT-A transporter, extends for more that 300 kb. The four known rat mRNA isoforms: UT-A1, UT-A2, UT-A3, and UT-A4 are transcribed from 24 exons. The Slc14a2 genomic map also accounts for 3′-untranslated sequences expressed alternatively in UT-A1, UT-A2, and UT-A3. We previously identified a TATA-less, tonicity-responsive promoter controlling the transcription of UT-A1, UT-A3, and UT-A4 from a single initiation site in the 5′-flanking region of the gene. Here, we describe a second, internal promoter in intron 12, which controls the transcription of UT-A2 starting from exon 13. This region contains a TATA motif upstream from the UT-A2 transcription start site, and shows consensus sequences for the cAMP response element (CRE) and for the tonicity enhancer (TonE) motif. Stimulation by cAMP induces UT-A2 mRNA expression in mIMCD3 cells, and luciferase activity in mIMCD3 cells transfected with those pGL3 constructs including the CRE sequences. Although long-term exposure to hypertonicity induces UT-A2 expression in mIMCD3 cells, hypertonicity does not induce significantly the activity of the promoter in intron 12. In summary, we describe the genomic structure of the rat UT-A urea transporter, encoded by the Slc14a2 gene. Our findings suggest that two promoters regulate transcription of the four UT-A isoforms, and that stimulation of transcription by vasopressin, mediated by cAMP and CRE sequences, and controlled by an intronic promoter, may contribute to the increase in UT-A2 expression during water deprivation.

Original languageEnglish (US)
Pages (from-to)19-26
Number of pages8
JournalBiochimica et Biophysica Acta - Gene Structure and Expression
Volume1518
Issue number1-2
DOIs
StatePublished - Mar 19 2001
Externally publishedYes

Keywords

  • Kidney
  • Slc14a2 gene
  • Urea
  • Urea transporter UT-A
  • Urea transporter isoform UT-A2
  • Vasopressin

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Genetics

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