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Methionine Adenosyltransferase 2A Positively Regulates Bcl‐2 Expression in a Ubiquitin‐Conjugating Enzyme 9‐Dependent Manner
Author(s) -
Tomasi Maria Lauda,
Lu Shelly C.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.145.10
Subject(s) - methionine adenosyltransferase , gene knockdown , sumo protein , apoptosis , messenger rna , chemistry , methionine , cell culture , ubiquitin , microbiology and biotechnology , ubiquitin conjugating enzyme , enzyme , ubiquitin ligase , gene , biology , biochemistry , amino acid , genetics
BACKGROUND & AIMS Ubiquitin‐conjugating enzyme 9 (Ubc9) is required for sumoylation and inhibits apoptosis via Bcl‐2 expression by unknown mechanism. Ubc9 and Bcl‐2 expression is up‐regulated in several malignancies. S‐adenosylmethionine (SAMe) is the methyl donor synthesized by methionine adenosyltransferase (MAT). MATII, encoded by MAT2A, is overexpressed in liver and colon cancers. SAMe decreases MAT2A expression and is pro‐apoptotic in cancer cells. Here we investigated whether MAT2A's effect on apoptosis may involve Bcl‐2 and Ubc9. METHODS Our studies used human colon and liver cancer cell lines RKO and Huh‐7, respectively. Gene and protein expression, Bcl2 promoter activity and protein binding were measured. RESULTS SAMe and its metabolite methylthioadenosine (MTA) treatment lowered Bcl‐2 expression at mRNA and protein levels by 55–80%. Knockdown of Ubc9 lowered MAT2A protein (but not mRNA) levels by 25%. Knockdown of MAT2A reduced Bcl‐2 mRNA level and Bcl‐2 promoter activity by 50–65%, while MAT2A overexpression doubled Bcl2 promoter activity in both cell types. Chip assay showed that MATII could physically interact with Bcl‐2 promoter in an Ubc9‐dependent manner. CONCLUSIONS MATII binds to the Bcl‐2 promoter region and this requires Ubc9. Ubc9's protective effect on apoptosis may be mediated at least in part by enhancing MATII expression, which in turn positively maintains Bcl‐2 expression. This work was supported by NIH grants R01DK51719, R01AT1576 and R01AT004896 (SC Lu), and F32AA020150 (ML Tomasi). Huh‐7 and RKO cells were provided by the Cell Culture Core of the USC Research Center for Liver Diseases (P30DK48522).