title: Multiple TSC22D4 iso-/phospho-glycoforms display idiosyncratic subcellular localizations and interacting protein partners.
abstract: Proteins of the TSC22 domain (TSC22D) family, including TSC22D1 and TSC22D4, play pivotal roles in cell proliferation, differentiation and apoptosis, interacting with other factors in a still largely unknown manner. This study explores this issue by biochemically characterizing various TSC22D4 forms (both iso- and glyco-phospho-, namely the splice variants 42 and 55 kDa and the post-translationally modified 67 and 72 kDa forms) and their subcellular localization and protein partners during cerebellar granule neuron (CGN) differentiation. The TSC22D4-42 form is mostly cytosolic, and is the only TSC22D4 form that associates with TSC22D1.2 in undifferentiated but not differentiated CGNs. In contrast, TSC22D4-55 is prominently associated with the nuclear matrix in differentiated but not undifferentiated CGNs. As for TSC22D4-67, it is localized in the cytosol and nuclei of undifferentiated CGNs and enters mitochondria of differentiated CGNs, associating with apoptosis-inducing factor. TSC22D4-72 is modified by O-linked beta-N-acetylglucosamine (O-GlcNAcylated) and phosphorylated and is always associated with chromatin irrespective of CGN differentiation. The various subcellular localization patterns and interacting protein partners of TSC22D4 forms during CGN differentiation suggest the existence of form-specific function(s) and provide a novel framework to further investigate the biological functions of TSC22D proteins.
authors.affiliation: Department of Psychology, Pasteur Institute-Cenci Bolognetti Foundation and Daniel Bovet Neurobiology Research Center, Sapienza University of Rome, Rome, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Canterini
authors.forename: Valentina
authors.initials: V
authors.lastname: Carletti
authors.forename: Stefania
authors.initials: S
authors.lastname: Nusca
authors.forename: Franco
authors.initials: F
authors.lastname: Mangia
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Fiorenza
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D000831:Animals, Newborn; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D002843:Chromatin / Q000235:genetics; D003594:Cytoplasmic Granules / Q000378:metabolism*; D006031:Glycosylation; D047468:Immunoprecipitation; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D013347:Subcellular Fractions; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D051033:Apoptosis Inducing Factor; D002843:Chromatin; D020033:Protein Isoforms; C443111:Spacdr protein, mouse; D014157:Transcription Factors