Papers In Press, published online ahead of print March 14, 2006
J. Biol. Chem, 10.1074/jbc.M513278200
Submitted on December 13, 2005
Revised on March 14, 2006
Accepted on March 14, 2006
Identification of T-cadherin as a novel target of DNA methyltransferase 3B and its role in the suppression of NGF-mediated neurite outgrowth in PC12 cells
Shoumei Bai, Kalpana Ghoshal, and Samson T. Jacob
Molecular and Cellular Biochemistry, the Ohio State University, College of Medicine, Columbus, OH 43210
Corresponding Author: jacob.42{at}osu.edu
Previously we showed that DNA methyltransferase 3b (Dnmt3b)1 is required for NGF-induced differentiation of PC12 cells to neuronal phenotype. The present study identified T-cadherin (T-Cad) as one of the targets of Dnmt3b by chromatin immunoprecipitation (ChIP) assay. Combined bisulfite restriction analysis (COBRA) and bisulfite sequencing showed that T-Cad promoter was sparsely methylated in PC12 cells. ChIP-CHOP analysis demonstrated that Dnmt3b is associated with T-Cad promoter irrespective of its methylation status. The mRNA and protein levels of T-Cad were markedly elevated in cells depleted of Dnmt3b by antisense or siRNA. Suppression of T-Cad promoter activity by Dnmt3b was independent of its catalytic activity, which was consistent with the insignificant change in T-Cad promoter methylation status in Dnmt3b-depleted cells. In contrast, deletion of its N-terminal ATRX and PWWP domain abolished its repressor function. Association of histone deacetylase 2 (Hdac2) with T-Cad promoter and restoration of the promoter activity from Dnmt3b-mediated suppression upon treatment with Hdac inhibitor indicated involvement of histone deacetylation in this process. NGF-induced neurite outgrowth was inhibited in a dose dependent manner upon ectopic expression of T-Cad in PC12 cells. Immunofluorescence studies showed that T-Cad was redistributed upon NGF treatment, as evident from its concentration in axon growth cones as opposed to its localization at cell-cell contact region in undifferentiated cells. These results demonstrate a novel role of T-Cad in the NGF-mediated differentiation of PC12 cells to neuronal phenotype.