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

Autor: Yanna Cao, Lu Chen, Weili Zhang, Yan Liu, Papaconstantinou, Harry T., Bush, Craig R., Townsend, Jr., Courtney M., Thompson, E. Aubrey, Ko, Tien C.
Předmět:
Zdroj: American Journal of Physiology: Gastrointestinal & Liver Physiology; Jan2007, Vol. 292, pG28-G38, 11p, 1 Chart, 8 Graphs
Abstrakt: 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 oligo- nucleotide 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. Further- more, 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. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index