TY - JOUR
T1 - Differential effects of wilms tumor WT1 splice variants on the insulin receptor promoter
AU - Webster, Nicholas J.G.
AU - Kong, Yan
AU - Sharma, Prem
AU - Haas, Martin
AU - Sukumar, Saraswati
AU - Seely, B. Lynn
N1 - Funding Information:
This work was supported by grants from the NIH (DK44643), the Department of Veterans Affairs, and the American Diabetes Association. N.J.G.W. is a faculty member of the UCSD Biomedical Sciences Graduate Program.
PY - 1997/12
Y1 - 1997/12
N2 - The Wilms tumor gene WT1 has been implicated in the early development of the kidney. Mutations in WT1 are found in a small fraction of Wilms tumor, a pediatric nephroblastoma, and Denys-Drash syndrome, characterized by genitourinary abnormalities. The WT1 gene product functions as a transcriptional repressor of growth factor-related genes. The kidney is one of the major sites of insulin action in vivo and expresses high levels of insulin receptors (IR). IR expression has been detected during early embryogenesis, suggesting that it may play a role in development. We investigated whether two WT1 splice variants lacking or including a three- amino-acid (KTS) insertion between the third and fourth zinc finger in the DNA-binding domain could repress the IR promoter in vitro. We show that the +KTS variant effectively represses promoter activity under all conditions tested but the -KTS variant was only able to repress in the presence of cotransfected C/EBPβ or a dominant-negative p53 mutation. Deletional mapping indicated that distinct regions of the IR promoter mediated the effects of the two isoforms and DNaseI footprint analysis identified potential WT1 binding sites within these regions.
AB - The Wilms tumor gene WT1 has been implicated in the early development of the kidney. Mutations in WT1 are found in a small fraction of Wilms tumor, a pediatric nephroblastoma, and Denys-Drash syndrome, characterized by genitourinary abnormalities. The WT1 gene product functions as a transcriptional repressor of growth factor-related genes. The kidney is one of the major sites of insulin action in vivo and expresses high levels of insulin receptors (IR). IR expression has been detected during early embryogenesis, suggesting that it may play a role in development. We investigated whether two WT1 splice variants lacking or including a three- amino-acid (KTS) insertion between the third and fourth zinc finger in the DNA-binding domain could repress the IR promoter in vitro. We show that the +KTS variant effectively represses promoter activity under all conditions tested but the -KTS variant was only able to repress in the presence of cotransfected C/EBPβ or a dominant-negative p53 mutation. Deletional mapping indicated that distinct regions of the IR promoter mediated the effects of the two isoforms and DNaseI footprint analysis identified potential WT1 binding sites within these regions.
UR - http://www.scopus.com/inward/record.url?scp=0031404951&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031404951&partnerID=8YFLogxK
U2 - 10.1006/bmme.1997.2648
DO - 10.1006/bmme.1997.2648
M3 - Article
C2 - 9441865
AN - SCOPUS:0031404951
SN - 1077-3150
VL - 62
SP - 139
EP - 150
JO - Biochemical and Molecular Medicine
JF - Biochemical and Molecular Medicine
IS - 2
ER -