GATA4 mutations are a cause of neonatal and childhood-onset diabetes.
ABSTRACT: The GATA family zinc finger transcription factors GATA4 and GATA6 are known to play important roles in the development of the pancreas. In mice, both Gata4 and Gata6 are required for pancreatic development. In humans, GATA6 haploinsufficiency can cause pancreatic agenesis and heart defects. Congenital heart defects also are common in patients with GATA4 mutations and deletions, but the role of GATA4 in the developing human pancreas is unproven. We report five patients with deletions (n = 4) or mutations of the GATA4 gene who have diabetes and a variable exocrine phenotype. In four cases, diabetes presented in the neonatal period (age at diagnosis 1-7 days). A de novo GATA4 missense mutation (p.N273K) was identified in a patient with complete absence of the pancreas confirmed at postmortem. This mutation affects a highly conserved residue located in the second zinc finger domain of the GATA4 protein. In vitro studies showed reduced DNA binding and transactivational activity of the mutant protein. We show that GATA4 mutations/deletions are a cause of neonatal or childhood-onset diabetes with or without exocrine insufficiency. These results confirm a role for GATA4 in normal development of the human pancreas.
Project description:Gata4, Gata5, and Gata6 represent a subfamily of zinc-finger transcriptional regulators that are important in the development and differentiation of numerous tissues, including many endodermally-derived organs. We demonstrate that Gata4 and Gata6 have overlapping expression patterns in the early pancreatic epithelium. Later, Gata4 becomes restricted to exocrine tissue and Gata6 becomes restricted to a subset of endocrine cells. In addition, we show Gata6, but not Gata4, physically interacts with Nkx2.2, an essential islet transcription factor. To begin determining the roles that Gata4 and Gata6 play during pancreatic development, we expressed Gata4-Engrailed and Gata6-Engrailed dominant repressor fusion proteins in the pancreatic epithelium and in the islet. At e17.5, transgenic Gata6-Engrailed embryos exhibit two distinct phenotypes: a complete absence of pancreas or a reduction in pancreatic tissue. In the embryos that do form pancreas, there is a significant reduction of all pancreatic cell types, with the few differentiated endocrine cells clustered within, or in close proximity to, enlarged ductal structures. Conversely, the majority of transgenic Gata4-Engrailed embryos do not have a pancreatic phenotype. This study suggests that Gata6 is an important regulator of pancreas specification.
Project description:Pancreatic agenesis is a human disorder caused by defects in pancreas development. To date, only a few genes have been linked to pancreatic agenesis in humans, with mutations in pancreatic and duodenal homeobox 1 (PDX1) and pancreas-specific transcription factor 1a (PTF1A) reported in only 5 families with described cases. Recently, mutations in GATA6 have been identified in a large percentage of human cases, and a GATA4 mutant allele has been implicated in a single case. In the mouse, Gata4 and Gata6 are expressed in several endoderm-derived tissues, including the pancreas. To analyze the functions of GATA4 and/or GATA6 during mouse pancreatic development, we generated pancreas-specific deletions of Gata4 and Gata6. Surprisingly, loss of either Gata4 or Gata6 in the pancreas resulted in only mild pancreatic defects, which resolved postnatally. However, simultaneous deletion of both Gata4 and Gata6 in the pancreas caused severe pancreatic agenesis due to disruption of pancreatic progenitor cell proliferation, defects in branching morphogenesis, and a subsequent failure to induce the differentiation of progenitor cells expressing carboxypeptidase A1 (CPA1) and neurogenin 3 (NEUROG3). These studies address the conserved and nonconserved mechanisms underlying GATA4 and GATA6 function during pancreas development and provide a new mouse model to characterize the underlying developmental defects associated with pancreatic agenesis.
Project description:Recently, heterozygous mutations in GATA6 have been found in neonatal diabetic patients with failed pancreatic organogenesis. To investigate the roles of GATA4 and GATA6 in mouse pancreas organogenesis, we conditionally inactivated these genes within the pancreas. Single inactivation of either gene did not have a major impact on pancreas formation, indicating functional redundancy. However, double Gata4/Gata6 mutant mice failed to develop pancreata, died shortly after birth, and displayed hyperglycemia. Morphological defects in Gata4/Gata6 mutant pancreata were apparent during embryonic development, and the epithelium failed to expand as a result of defects in cell proliferation and differentiation. The number of multipotent pancreatic progenitors, including PDX1+ cells, was reduced in the Gata4/Gata6 mutant pancreatic epithelium. Remarkably, deletion of only 1 Gata6 allele on a Gata4 conditional knockout background severely reduced pancreatic mass. In contrast, a single WT allele of Gata4 in Gata6 conditional knockout mice was sufficient for normal pancreatic development, indicating differential contributions of GATA factors to pancreas formation. Our results place GATA factors at the top of the transcriptional network hierarchy controlling pancreas organogenesis.
Project description:We recently reported de novo GATA6 mutations as the most common cause of pancreatic agenesis, accounting for 15 of 27 (56%) patients with insulin-treated neonatal diabetes and exocrine pancreatic insufficiency requiring enzyme replacement therapy. We investigated the role of GATA6 mutations in 171 subjects with neonatal diabetes of unknown genetic etiology from a cohort of 795 patients with neonatal diabetes. Mutations in known genes had been confirmed in 624 patients (including 15 GATA6 mutations). Sequencing of the remaining 171 patients identified nine new case subjects (24 of 795, 3%). Pancreatic agenesis was present in 21 case subjects (six new); two patients had permanent neonatal diabetes with no enzyme supplementation and one had transient neonatal diabetes. Four parents with heterozygous GATA6 mutations were diagnosed with diabetes outside the neonatal period (12-46 years). Subclinical exocrine insufficiency was demonstrated by low fecal elastase in three of four diabetic patients who did not receive enzyme supplementation. One parent with a mosaic mutation was not diabetic but had a heart malformation. Extrapancreatic features were observed in all 24 probands and three parents, with congenital heart defects most frequent (83%). Heterozygous GATA6 mutations cause a wide spectrum of diabetes manifestations, ranging from pancreatic agenesis to adult-onset diabetes with subclinical or no exocrine insufficiency.
Project description:The zinc-finger transcription factors GATA4 and GATA6 play critical roles in embryonic development. Mouse embryos lacking GATA4 die at embryonic day (E) 8.5 because of failure of ventral foregut closure and cardiac bifida, whereas GATA6 is essential for development of the visceral endoderm. Although mice that are heterozygous for either a GATA4 or GATA6 null allele are normal, we show that compound heterozygosity of GATA4 and GATA6 results in embryonic lethality by E13.5 accompanied by a spectrum of cardiovascular defects, including thin-walled myocardium, ventricular and aortopulmonary septal defects, and abnormal smooth muscle development. Myocardial hypoplasia in GATA4/GATA6 double heterozygous mutant embryos is associated with reduced proliferation of cardiomyocytes, diminished expression of the myogenic transcription factor MEF2C (myocyte enhancer factor 2C), and down-regulation of beta-myosin heavy chain expression, a key determinant of cardiac contractility. These findings reveal a threshold of GATA4 and GATA6 activity that is required for gene expression in the developing cardiovascular system and underscore the potential of recessive mutations to perturb the delicate regulation of cardiovascular development.
Project description:GATA4 and GATA6 are zinc-finger transcription factors that regulate specific genes involved in steroidogenesis. Using RNA interference (RNAi)-mediated reduction of GATA4 and/or GATA6 with microarray analysis, we aimed to identify novel GATA target genes in luteinizing porcine granulosa cells under vehicle- and cAMP-treated conditions. Microarray analysis identified IGF1 mRNA to be cAMP- and GATA-responsive, and real-time PCR demonstrated that the cAMP-induced increase in IGF1 mRNA was reduced under conditions of GATA6 depletion and GATA4 plus GATA6 depletion, but not GATA4 depletion. Insulin-like growth factor 1 protein levels in media were also decreased by GATA6 or GATA4 plus GATA6 reduction. IGFBP2 and IGFBP4 mRNAs were increased and IGFBP5 mRNA decreased with vehicle and cAMP treatment under GATA4 plus GATA6 RNAi conditions. GATA6 reduction alone increased basal IGFBP4 and decreased IGFBP5 with both vehicle and cAMP, and GATA4 reduction alone lowered cAMP IGFBP5 levels with cAMP. No changes in IGFBP3 mRNA were observed with GATA reduction relative to the control RNAi condition. Levels of insulin-like growth factor binding proteins 2-5 in media as assessed by Western ligand blotting were not altered by GATA reduction. Electromobility gel shift assays with two GATA-containing oligonucleotides of the IGF1 5'-regulatory region showed GATA4 and GATA6 could bind the more proximal GATA-B site. These studies indicate that although GATA4 and GATA6 can bind the porcine IGF1 5'-region, GATA6 is functionally most important for cAMP-stimulated mRNA levels. Using microarray analysis, we identified other mRNAs that were altered by GATA-reduced conditions, including ALDH1, DIO2, and EDNRB. Our findings further support GATA as a coordinator of endocrine/paracrine/autocrine signals in the ovary.
Project description:The family of zinc finger-containing GATA transcription factors plays critical roles in cell lineage specification during early embryonic development and organ formation. GATA4 and GATA6 were found to be frequently lost in ovarian cancer, and the loss is proposed to account for dedifferentiation of the cancer cells.We further investigated the expression of GATA4 and GATA6 in ovarian surface epithelial lesions and histological subtypes of ovarian carcinomas by immunostaining. GATA4 and GATA6 were found to be absent in high percentages (80 to 90%) of serous, clear cell, and endometrioid ovarian cancer examined. In contrast, both were found positive in 11 out of 12 cases of mucinous carcinomas, suggesting the expression of the GATA factors can distinguish mucinous cancer from other histological subtypes. GATA4 was frequently lost in preneoplastic lesions such as morphologically normal inclusion cysts and epithelial hyperplasia adjacent to malignant cells. The loss of GATA6 correlates closely with neoplastic morphological transformation of ovarian surface epithelia. In culture, GATA4 expression was progressively reduced upon passaging primary ovarian surface epithelial cells, which correlated with changes in histone modification of the GATA4 locus. A reduced GATA6 gene dosage as in GATA6 (+/-) mice led to an increased pre-neoplastic changes and inclusion cysts in the ovaries, suggesting the loss of GATA6 contributes to ovarian cancer development.This study suggests that the expression status of GATA4 and GATA6 may dictate distinct pathologic pathways leading to serous or mucinous ovarian carcinomas. The readily loss of GATA4 expression through changes in chromatin conformation suggests a potential non-phenotypic initiating event, leading to subsequent loss of GATA6, morphological transformation, and ultimate tumorigenesis.
Project description:Cardiac hypertrophy is regulated by the zinc finger-containing DNA binding factors Gata4 and Gata6, both of which are required to mount a productive growth response of the adult heart. To determine if Gata4 and Gata6 are redundant or have non-overlapping roles, we performed cardiomyocyte-specific conditional gene deletions for Gata4 and Gata6 in conjunction with reciprocal replacement with a transgene encoding either Gata4 or Gata6, during the pressure overload response. We determined that Gata4 and Gata6 play a redundant and dosage-sensitive role in programming the hypertrophic growth response itself following pressure overload stimulation. However, non-redundant functions were identified as functional decompensation induced by either Gata4 or Gata6 deletion was not rescued by the reciprocal transgene, and only Gata4 heart-specific deletion produced a reduction in capillary density after pressure overload. Gene expression profiling from hearts of these gene-deleted mice showed both overlapping and unique transcriptional codes, with Gata4 exhibiting the strongest impact. These results indicate that Gata4 and Gata6 play a dosage-dependent and semi-redundant role in programming cardiac hypertrophy, but that each has a unique role in maintaining cardiac homeostasis and adaptation to injury that cannot be compensated by the other. Microarray-bassed gene expression profiling identified overlapping, distinct, and quantitatively/differentially regulated classes of Gata4 or Gata6 regulated genes. To determine if Gata4 and Gata6 are redundant or have non-overlapping roles in programming cardiac hypertrophic responses and adaptation to stress or injury, we performed cardiomyocyte-specific conditional gene deletions for Gata4 and Gata6 in conjunction with reciprocal replacement with a transgene encoding either Gata4 or Gata6, during the pressure overload response.
Project description:The Gata4/5/6 sub-family of zinc finger transcription factors regulate many aspects of cardiogenesis. However, critical roles in extra-embryonic endoderm also challenge comprehensive analysis during early mouse cardiogenesis, while zebrafish models have previously relied on knockdown assays. We generated targeted deletions to disrupt each gata4/5/6 gene in zebrafish and analyzed cardiac phenotypes in single, double and triple mutants. The analysis confirmed that loss of gata5 causes cardia bifida and validated functional redundancies for gata5/6 in cardiac precursor specification. Surprisingly, we discovered that gata4 is dispensable for early zebrafish development, while loss of one gata4 allele can suppress the bifid phenotype of the gata5 mutant. The gata4 mutants eventually develop an age-dependent cardiomyopathy. By combining combinations of mutant alleles, we show that cardiac specification depends primarily on an overall dosage of gata4/5/6 alleles rather than a specific gene. We also identify a specific role for gata6 in controlling ventricle morphogenesis through regulation of both the first and second heart field, while loss of both gata4/6 eliminates the ventricle. Thus, different developmental programs are dependent on total dosage, certain pairs, or specific gata4/5/6 genes during embryonic cardiogenesis.This article has an associated First Person interview with the first author of the paper.
Project description:The intestinal epithelium performs vital roles in organ function by absorbing nutrients and providing a protective barrier. The zinc-finger containing transcription factors GATA4 and GATA6 regulate enterocyte gene expression and control regional epithelial cell identity in the adult intestinal epithelium. Although GATA4 and GATA6 are expressed in the developing intestine, loss of either factor alone during the period of epithelial morphogenesis and cytodifferentiation fails to disrupt these processes. Therefore, we tested the hypothesis that GATA4 and GATA6 function redundantly to control these aspects of intestinal development. We used Villin-Cre, which deletes specifically in the intestinal epithelium during the period of villus development and epithelial cytodifferentiation, to generate Gata4Gata6 double conditional knockout embryos. Mice lacking GATA4 and GATA6 in the intestinal epithelium died within 24h of birth. At E18.5, intestinal villus architecture and epithelial cell populations were altered. Enterocytes were lost, and goblet cells were increased. Proliferation was also increased in GATA4-GATA6 deficient intestinal epithelium. Although villus morphology appeared normal at E16.5, the first time at which both Gata4 and Gata6 were efficiently reduced, changes in expression of markers of enterocytes, goblet cells, and proliferative cells were detected. Moreover, goblet cell number was increased at E16.5. Expression of the Notch ligand Dll1 and the Notch target Olfm4 were reduced in mutant tissue indicating decreased Notch signaling. Finally, we found that GATA4 occupies chromatin near the Dll1 transcription start site suggesting direct regulation of Dll1 by GATA4. We demonstrate that GATA4 and GATA6 play an essential role in maintaining proper intestinal epithelial structure and in regulating intestinal epithelial cytodifferentiation. Our data highlight a novel role for GATA factors in fine tuning Notch signaling during intestinal epithelial development to repress goblet cell differentiation.