Identification of apoptotic genes mediating TGF-β/Smad3-induced cell death in intestinal epithelial cells using a genomic approach

Yanna Cao, Lu Chen, Weili Zhang, Yan Liu, Harry T. Papaconstantinou, Craig R. Bush, Courtney Townsend, E. Aubrey Thompson, Tien C. Ko

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20 Scopus citations


Transforming growth factor (TGF)-β-dependent apoptosis is important in the elimination of damaged or abnormal cells from normal tissues in vivo. Previously, we have shown that TGF-β inhibits the growth of rat intestinal epithelial (RIE)-1 cells. However, RIE-1 cells are relatively resistant to TGF-β-induced apoptosis due to a low endogenous Smad3-to-Akt ratio. Overexpression of Smad3 sensitizes RIE-1 cells (RIE-1/Smad3) to TGF-β-induced apoptosis by altering the Smad3-to-Akt ratio in favor of apoptosis. In this study, we utilized a genomic approach to identify potential downstream target genes that are regulated by TGF-β/Smad3. Total RNA samples were analyzed using Affymetrix oligonucleotide microarrays. We found that TGF-β regulated 518 probe sets corresponding to its target genes. Interestingly, among the known apoptotic genes included in the microarray analyses, only caspase-3 was induced, which was confirmed by real-time RT-PCR. Furthermore, TGF-β activated caspase-3 through protein cleavage. Upstream of caspase-3, TGF-β induced mitochondrial depolarization, cytochrome c release, and cleavage of caspase-9, which suggests that the intrinsic apoptotic pathway mediates TGF-β-induced apoptosis in RIE-1/Smad3 cells.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number1
StatePublished - Jan 2007



  • Affymetrix oligonucleotide microarrays
  • Apoptosis
  • Caspases
  • Transforming growth factor-β

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology

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