title: Identification and characterization of C106R, a novel mutation in the DNA-binding domain of GCMB, in a family with autosomal-dominant hypoparathyroidism.
abstract: BACKGROUND
  Glial cells missing B (GCMB) is a transcription factor that is expressed in the parathyroid hormone (PTH)-secreting cells of the parathyroid glands. Several mutations in GCMB have been reported to cause hypoparathyroidism (HP). We identified a family with two individuals in two generations (mother and son), who are affected by autosomal-dominant hypoparathyroidism (AD-HP). A novel heterozygous mutation in exon 2 of GCMB was identified in both affected individuals that changes cysteine at position 106 of the putative DNA-binding domain of GCMB to arginine (C106R).
  
  
  METHODS
  We performed mutational analysis of the genes encoding GCMB, pre-pro PTH, GATA3 and CaSR using polymerase chain reaction (PCR)-amplified genomic DNA. The identified GCMB mutant was characterized by functional studies including nuclear localization, electrophoretic mobility shift assays (EMSA) and luciferase reporter assays, and homology modelling was performed to generate a three-dimensional structural model for the DNA-binding domain of GCMB to predict the structural consequences of the identified mutation.
  
  
  RESULTS
  The C106R mutant of GCMB failed to interact with the DNA consensus recognition motif, as determined by EMSA. Furthermore, in comparison with wild-type GCMB, the C106R mutant demonstrated reduced transactivation in luciferase reporter assays; however, the mutant GCMB failed to reduce the activity of the wild-type protein. Consistent with the EMSA findings, homology modelling analysis suggested that replacement of cysteine 106 with arginine would interfere with DNA binding.
  
  
  CONCLUSIONS
  We have identified a novel GCMB mutation that may explain AD-HP in our family. However, the exact mechanism by which this heterozygous mutation leads to the disease in the described family remains to be elucidated.
authors: Department of Internal Medicine and Laboratory of Molecular Endocrinology, Gachon University School of Medicine, Incheon, Korea.
authors: Hyon-Seung
authors: HS
authors: Yi
authors: Young Sil
authors: YS
authors: Eom
authors: Ie Byung
authors: IeB
authors: Park
authors: Sangho
authors: S
authors: Lee
authors: Suntaek
authors: S
authors: Hong
authors: Harald
authors: H
authors: Jüppner
authors: Michael
authors: M
authors: Mannstadt
authors: Sihoon
authors: S
authors: Lee
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis; D005192:Family Health; D005260:Female; D005799:Genes, Dominant / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D007011:Hypoparathyroidism / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009690:Nucleic Acid Conformation; D010375:Pedigree; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: C119532:GCM2 protein, human; D009687:Nuclear Proteins; D014157:Transcription Factors; D004247:DNA