Smad1, β-catenin and Tcf4 associate in a molecular complex with the Myc promoter in dysplastic renal tissue and cooperate to control Myc transcription

Ming C Hu, Norman D. Rosenblum

Research output: Contribution to journalArticle

74 Scopus citations

Abstract

Renal dysplasia, the major cause of childhood renal failure in humans, arises from perturbed renal morphogenesis and molecular signaling during embryogenesis. Recently, we discovered induction of molecular crosstalk between Smad1 and β-catenin in the TgAlk3QD mouse model of renal medullary cystic dysplasia. Our finding that Myc, a Smad and β-catenin transcriptional target and effector of renal epithelial dedifferentiation, is misexpressed in dedifferentiated epithelial tubules provided a basis for investigating coordinate transcriptional control by Smad1 and β-catenin in disease. Here, we report enhanced interactions between a molecular complex consisting of Smad1, β-catenin and Tcf4 and adjacent Tcf- and Smad-binding regions located within the Myc promoter in TgAlk3QD dysplastic renal tissue, and Bmp-dependent cooperative control of Myc transcription by Smad1, β-catenin and Tcf4. Analysis of nuclear extracts derived from TgAlk3QD and wild-type renal tissue revealed increased levels of Smad1/β-catenin molecular complexes, and de novo formation of chromatin-associated Tcf4/Smad1 molecular complexes in TgAlk3QD tissues. Analysis of a 476 nucleotide segment of the 1490 nucleotide Myc genomic region upstream of the transcription start site demonstrated interactions between Tcf4 and the Smad consensus binding region and associations of Smad1, β-catenin and Tcf4 with oligo-duplexes that encode the adjacent Tcf- and Smad-binding elements only in TgAlk3QD tissues. In collecting duct cells that express luciferase under the control of the 1490 nucleotide Myc genomic region, Bmp2-dependent stimulation of Myc transcription was dependent on contributions by each of Tcf-4, β-catenin and Smad1. These results provide novel insights into mechanisms by which interacting signaling pathways control transcription during the genesis of renal dysplasia.

Original languageEnglish (US)
Pages (from-to)215-225
Number of pages11
JournalDevelopment
Volume132
Issue number1
DOIs
Publication statusPublished - Jan 2005

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Keywords

  • β-catenin
  • Cystogenesis
  • Myc
  • Renal dysplasia
  • Smad1
  • Tcf4

ASJC Scopus subject areas

  • Anatomy
  • Cell Biology

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