title: Mutational analysis of GCMB, a parathyroid-specific transcription factor, in parathyroid adenoma of primary hyperparathyroidism.
abstract: Sporadic primary hyperparathyroidism (PHPT), one of the most common endocrine disorders, is characterized by hypercalcemia and elevated PTH levels. The majority of cases are caused by a benign parathyroid adenoma, but somatic or de novo germ-line mutations that lead to adenoma formation have only been identified in few glands. GCMB is a parathyroid-specific transcription factor, which causes hypoparathyroidism when inactivated on both parental alleles or when a dominant-negative, heterozygous mutation is present. It is overexpressed in some parathyroid adenomas, and we therefore tested the hypothesis that GCMB mutations can be a cause of parathyroid adenomas. Nucleotide sequence analysis was performed on all coding exons and exon-intron borders of GCMB in 30 sporadic parathyroid adenomas and we identified several known polymorphisms that were either heterozygous or homozygous. In addition, one of the 30 investigated glands revealed a novel heterozygous missense mutation, c.1144G>A, which introduced methionine at position 382 for valine (V382M), a conserved amino acid residue. Western blot analysis using mutant GCMB (GCMB-V382M) from lysates of transiently transfected DF-1 fibroblasts, luciferase assays using extracts from these cells, and electrophoretic mobility assays failed to reveal differences between wild-type and mutant GCMB in expression level, transactivational capacity, and DNA-binding ability. Furthermore, pulse-chase experiments demonstrated no difference in half-life of wild-type and mutant protein. We conclude that mutations in the transcription factor GCMB do not seem to play a major role in the pathogenesis of PHPT.
authors.affiliation: Endocrine Unit Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Thier 1051, 55 Fruit Street, Boston, Massachusetts 02114, USA. mmannstadt@partners.org
authors.forename: Michael
authors.initials: M
authors.lastname: Mannstadt
authors.forename: Emily
authors.initials: E
authors.lastname: Holick
authors.forename: Wenping
authors.initials: W
authors.lastname: Zhao
authors.forename: Harald
authors.initials: H
authors.lastname: Jüppner
mesh_terms: D000236:Adenoma / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D018095:Germ-Line Mutation; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000209:etiology / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010280:Parathyroid Glands / Q000378:metabolism; D010282:Parathyroid Neoplasms / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: C119532:GCM2 protein, human; D009687:Nuclear Proteins; D014157:Transcription Factors