title: Ubiquitin-like protein MNSFβ covalently binds to cytosolic 10-formyltetrahydrofolate dehydrogenase and regulates thymocyte function.
abstract: MNSFβ is a ubiquitously expressed member of the ubiquitin-like family that has been involved in various biological functions. Previous studies have demonstrated that MNSFβ covalently binds to various target proteins including Bcl-G, a proapoptotic protein. In this study, we purified a 115 kDa MNSFβ adduct from murine liver lysates by sequential chromatography on DEAE and anti-MNSFβ IgG-conjugated Sepharose in the presence of ATP. MALDI-TOF MS fingerprinting revealed that this MNSFβ adduct consists of an 8.5 kDa MNSFβ and 10-formyltetrahydrofolate dehydrogenase (FDH), an abundant enzyme of folate metabolism. Interestingly, MNSFβ preferably binds to cytosolic but not mitochondrial FDH. Fingerprinting analysis of the MNSFβ adduct demonstrate that MNSFβ conjugates to cytosolic FDH with a linkage between the C-terminal Gly74 and Lys72. The 115 kDa MNSFβ/FDH complex was not expressed in any of the tissues examined, indicating that this adduct formation is not ubiquitous. We found that MNSFβ/FDH complex formation was induced by dexamethasone in thymocytes. Double knockdown of MNSFβ and FDH strongly reduced dexamethasone-induced apoptosis. Collectively, MNSFβ/FDH complex formation may positively regulate apoptosis in thymocytes.
authors.affiliation: The Department of Cooperative Medical Research, Collaboration Center, Shimane University, Izumo 693-8501, Japan. Electronic address: nkmr0515@med.shimane-u.ac.jp.
authors.forename: Morihiko
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: The Department of Cooperative Medical Research, Collaboration Center, Shimane University, Izumo 693-8501, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Watanabe
authors.affiliation: The Department of Cooperative Medical Research, Collaboration Center, Shimane University, Izumo 693-8501, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Notsu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D051379:Mice; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D013491:Suppressor Factors, Immunologic / Q000737:chemistry / Q000378:metabolism*; D060168:Thymocytes / Q000166:cytology* / Q000378:metabolism*; D014452:Ubiquitins / Q000737:chemistry / Q000378:metabolism*; D000099295:Formyltetrahydrofolate Dehydrogenase
chemical_list: D000587:Oxidoreductases Acting on CH-NH Group Donors; D013491:Suppressor Factors, Immunologic; D014452:Ubiquitins; D000099295:Formyltetrahydrofolate Dehydrogenase; C072169:monoclonal nonspecific suppressor factor
keywords: Apoptosis; FDH; Thymocytes; Ubiquitin-like protein