GCMb

CONTEXT: The glial cells missing 2 ( GCM2 ) gene functions as a transcription factor that is essential for parathyroid gland development, and variants in this gene have been associated with 2 parathyroid diseases: isolated hypoparathyroidism in patients with homozygous germline inactivating variants and primary hyperparathyroidism in patients with heterozygous germline activating variants. A recurrent germline activating missense variant of GCM2 , p.Y394S, has been reported in patients with familial primary hyperparathyroidism...

Differentiated neurons and glia are acquired from immature precursors via transcriptional controls exerted by factors such as proteins in the family of Glial Cells Missing (Gcm). Mammalian Gcm proteins mediate neural stem cell induction, placenta and parathyroid development, whereas Drosophila Gcm proteins act as a key switch to determine neuronal and glial cell fates and regulate hemocyte development. The present study reports a hypoparathyroidism-associated mutation R59L that alters Drosophila Gcm (Gcm) protein stability, rendering it unstable, and hyperubiquitinated via the ubiquitin-proteasome system (UPS)...

BACKGROUND: Except after neck surgery, hypoparathyroidism is a rare disease caused by defects in genes involved in parathyroid gland development (TBX1/22q11.2 del, GCMB, GATA3, TBCE) or function [calcium sensing receptor (CASR), GNA11, PTH], or the autoimmune polyglandular syndrome type 1 (AIRE). Approximately 90% of sporadic cases and 30% of familial cases of isolated hypoparathyroidism remain unexplained. Recurrent missense mutations in AP2S1, a calcium-sensing receptor regulator, have been recently identified in familial hyperparathyroidism...

Isolated hypoparathyroidism (IH) shows heterogeneous phenotypes and can be caused by defects in a variety of genes. The goal of our study was to determine the clinical features and to analyze gene mutations in a large cohort of Korean patients with sporadic or familial IH. We recruited 23 patients. They showed a broad range of onset age and various values of biochemical data. Whole exome sequencing was performed on two affected cases and one unaffected individual in a family. All coding exons and exon-intron borders of GCMB, CASR, and prepro-PTH were sequenced using PCR-amplified DNA...

OVERVIEW: 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)...

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...

Expression of the PTH gene is known to be under strict tissue-specific control and is also regulated by extracellular calcium and 1,25(OH)(2)D. However, the precise mode of transcriptional regulation remains to be elucidated, because of the unavailability of appropriate cell lines derived from the parathyroid gland. We tried to identify the transcription factor(s) regulating the human PTH gene transcription using the PT-r cell line. We found that PT-r cells endogenously express PTH and several parathyroid-related genes...

Heterozygous mutations of GATA3, which encodes a dual zinc-finger transcription factor, cause hypoparathyroidism with sensorineural deafness and renal dysplasia. Here, we have investigated the role of GATA3 in parathyroid function by challenging Gata3+/- mice with a diet low in calcium and vitamin D so as to expose any defects in parathyroid function. This led to a higher mortality among Gata3+/- mice compared with Gata3+/+ mice. Compared with their wild-type littermates, Gata3+/- mice had lower plasma concentrations of calcium and parathyroid hormone (PTH) and smaller parathyroid glands with a reduced Ki-67 proliferation rate...

CONTEXT: Glial cells missing B (GCMB), the mammalian homolog of the Drosophila GCM gene, encodes a 506-amino-acid parathyroid-specific transcription factor. To date, only two different heterozygous GCMB mutations have been reported in three kindreds with autosomal dominant hypoparathyroidism. OBJECTIVE: Our objective was to investigate a family with autosomal dominant hypoparathyroidism for PTH, CaSR, and GCMB mutations. METHODS: Leukocyte DNA was used with exon-specific primers for PCR amplification and the DNA sequences of the PCR products determined...

GCMB is a member of the small transcription factor family GCM (glial cells missing), which are important regulators of development, present in vertebrates and some invertebrates. In man, GCMB encodes a 506 amino acid parathyroid gland-specific protein, mutations of which have been reported to cause both autosomal dominant and autosomal recessive hypoparathyroidism. We ascertained 18 affected individuals from 12 families with autosomal recessive hypoparathyroidism and have investigated them for GCMB abnormalities...

PURPOSE OF REVIEW: The purpose of this review is to describe the development and function of the parathyroid gland from fish to mammals. We describe the molecular mechanisms regulating parathyroid gland embryogenesis and the clinical syndromes related to mutations in control genes. RECENT FINDINGS: Recent studies have shown that fish express parathyroid hormone. This is contrary to the long held view that the earliest animals to possess parathyroid hormone were amphibians...

CONTEXT: Hypoparathyroidism (HP) is characterized by low PTH levels, hypocalcemia, and hyperphosphatemia. Heterozygous mutations in pre-pro-PTH or the calcium-sensing receptor (CaSR) cause some forms of autosomal dominant HP (AD-HP). Furthermore, homozygous mutations in glial cells missing B (GCMB) have been implicated in autosomal recessive HP (AR-HP). In most other HP patients, however, the molecular defect remains undefined. OBJECTIVE: Our objectives were to determine the genetic defect in the affected members of two unrelated families with AD-HP and define the underlying disease mechanism...

Members of the GCM (glial cells missing) transcription factor family have been shown to act as master regulators in different cells during mammalian and fly development being responsible for processes including gliogenesis, hematopoiesis, placental formation, and development of the parathyroidea. In the central nervous system of flies, several target genes for GCM have been reported, namely repo, pointed, and tramtrack. In mammals, two GCM genes are known (GCMa and GCMb), but the knowledge of their target genes is very limited...

Hypoparathyroidism, either of acquired or inherited origin, is a heterogenous group of human disorders caused by a defective calcium homeostasis clinically known as hypocalcemia and hyperphosphatemia. Two mutations (R47L, G63S) in the DNA binding domain of the parathyroid-specific transcription factor GCMB have been reported to be linked to hypoparathyroidism. Both mutations cause a loss of transactivation either with (R47L) or without (G63S) a concomitant loss of DNA binding. Despite these differences with respect to their DNA binding ability, molecular modeling of the wild type and mutant GCMB-DNA complexes reveals a common regular pattern of molecular interactions which is apparently crucial for the integrity of the GCM DNA binding domain and is altered by the respective mutations...

Isolated hypoparathyroidism is an uncommon metabolic disorder characterized by hypocalcemia and hyperphosphatemia, with absent or low levels of PTH. It may present as an apparently sporadic disorder or may be transmitted in families as a genetic trait. Mutations of the calcium-sensing receptor gene and of the preproPTH gene have been reported in occasional cases, and a mutation of the parathyroid-specific transcription factor GCMB gene has been reported in one familial case. We report a second family with isolated hypoparathyroidism and a GCMB mutation...

BACKGROUND: The glial cell missing gene, GCMB , encodes a transcription factor, which is a master regulator of parathyroid development. We postulated that the GCMB gene might play a role in parathyroid tumorigenesis in hyperparathyroidism. METHODS: We used real-time quantitative reverse transcriptase polymerase chain reaction to study GCMB mRNA expression in parathyroid tissue: normal (n = 3), hyperplastic (n = 16), adenomas (n = 19), and cancers (n = 8). In primary parathyroid culture, the effect of CaCl 2 on parathyroid hormone secretion and GCMB mRNA expression was studied by using enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction, respectively...

The GCM proteins GCMa/1 and GCMb/2 are novel zinc-containing transcription factors critical for glial cell differentiation in fly and for placental as well as parathyroid gland development in mouse. Previous pulse-chase experiments have demonstrated differential protein stabilities of GCM proteins with half-lives from approximately 30 min to 2 h (Tuerk, E. E., Schreiber, J., and Wegner, M. (2000) J. Biol. Chem. 275, 4774-4782). However, little is known about the machinery that controls GCM protein degradation...

The glial cells missing (gcm) gene in Drosophila encodes a GCM-motif transcription factor that functions as a binary switch to select between glial and neuronal cell fates. To understand the function of gcm in vertebrates, we isolated the zebrafish gcmb and analyzed the function of this gene using antisense morpholino oligonucleotides against gcmb mRNA (gcmb-MO) and transgenic overexpression. Zebrafish gcmb is expressed in the pharyngeal arch epithelium and in cells of the macrophage lineage. gcmb-MO-injected larvae show significantly reduced branchial arch cartilages...

GCMA and GCMB are related transcription factors that are critically important for embryological development of the placenta and parathyroid glands, respectively. Mice in which parathyroid glands have been surgically removed or fail to develop due to genetic loss of GCMB show continued production of PTH from a subset of thymic cells that express GCMA. In this study we examined whether human thymus produces PTH and/or GCMA and whether intrathymic PTH-secreting adenomas express GCMA or GCMB to determine the embryological origin of the secretory cells...

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