TY - JOUR
T1 - Cloning of the rat Slc14a2 gene and genomic organization of the UT-A urea transporter
AU - Nakayama, Yushi
AU - Naruse, Masahiro
AU - Karakashian, Alexander
AU - Peng, Tao
AU - Sands, Jeff M.
AU - Bagnasco, Serena M.
N1 - Funding Information:
We are grateful to Sharon Langley for her invaluable help in sequencing. Part of this study was funded by NIH Grants R01-DK41707, R01 DK53917 and P01-DK50268, and Grant-in-aid 96006090 from the American Heart Association. Yushi Nakayama was supported by the National Kidney Foundation of Georgia. Part of this work was presented in abstract form at the annual meeting of the American Society of Nephrology (A0107, J. Am. Soc. Nephrol. 8 (1997) 23A; A0107, J. Am. Soc. Nephrol. 10 (1999) 21A), and at the annual FASEB meeting (A392, FASEB J. 13 (1999); A348, FASEB J. 14 (2000)).
PY - 2001/3/19
Y1 - 2001/3/19
N2 - 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.
AB - 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.
KW - Kidney
KW - Slc14a2 gene
KW - Urea
KW - Urea transporter UT-A
KW - Urea transporter isoform UT-A2
KW - Vasopressin
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U2 - 10.1016/S0167-4781(00)00311-0
DO - 10.1016/S0167-4781(00)00311-0
M3 - Article
C2 - 11267655
AN - SCOPUS:0035911753
VL - 1518
SP - 19
EP - 26
JO - Biochimica et Biophysica Acta - Gene Structure and Expression
JF - Biochimica et Biophysica Acta - Gene Structure and Expression
SN - 0167-4781
IS - 1-2
ER -