title: Nuclear localisation of endogenous SUMO-1-modified PDGF-C in human thyroid tissue and cell lines.
abstract: We investigated post-translational modification and subcellular localisation of endogenous platelet-derived growth factor-C (PDGF-C) in human thyroid papillary carcinomas (PTC), non-neoplastic thyroid tissues, and a selection of cultured cell lines. PDGF-C expressed nuclear localisation in 95% of all tested cell types in culture and in 10% of the thyrocytes from both PTC and non-neoplastic tissue. The cell lines expressed two forms of full-length PDGF-C, approximately 39 and approximately 55 kDa, in cell membrane and cytosol, while the approximately 55 kDa form dominated in the nucleus where it was partly chromatin-associated. The approximately 55 kDa form was post-translationally modified by SUMO-1. The putative PDGF-C SUMOylation site is the surface exposed (314)lysine part of a positively charged loop ((312)RPKTGVRGLHK(322)) with characteristics of a nuclear localisation signal. The tissue thyrocytes expressed a non-SUMOylated approximately 43 kDa and the 55 kDa PDGF-C. The SUMO-1 modified approximately 55 kDa PDGF-C expression was low in PTC where the approximately 43 kDa PDGF-C dominated. This is in contrast to non-neoplastic tissue and cultured cells where the SUMOylated approximately 55 kDa PDGF-C was strongly expressed. Our data provide novel evidence for nuclear localisation of PDGF-C, post-translational modification by SUMOylation and the expression of a novel form of PDGF-C in human papillary thyroid carcinomas.
authors.affiliation: Department of Molecular Biology, University of Bergen, Section of Surgery, Haukeland University Hospital, Bergen 5020, Norway.
authors.forename: Laila J
authors.initials: LJ
authors.lastname: Reigstad
authors.forename: Aurora
authors.initials: A
authors.lastname: Martinez
authors.forename: Jan Erik
authors.initials: JE
authors.lastname: Varhaug
authors.forename: Johan R
authors.initials: JR
authors.lastname: Lillehaug
mesh_terms: D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002291:Carcinoma, Papillary / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008222:Lymphokines / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010982:Platelet-Derived Growth Factor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D025842:SUMO-1 Protein / Q000378:metabolism / Q000494:pharmacology*; D044967:Serum / Q000378:metabolism; D013961:Thyroid Gland / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002843:Chromatin; D008222:Lymphokines; D010982:Platelet-Derived Growth Factor; D025842:SUMO-1 Protein; C411423:platelet-derived growth factor C; D003609:Dactinomycin; D000077191:Wortmannin