Project description:Introduction: Maturity-onset Diabetes of the Young (MODY) is a rare form of diabetes and arises from mutations in key regulatory genes of the pancreatic beta-cell, leading to their functional impairment and early-onset diabetes. Research into PDX1-MODY, a form of MODY caused by mutations in the PDX1 gene, enhances understanding of gene-specific mechanisms underlying glucose dysregulation and provides insights into possible approaches to restore normal metabolic function. However, no currently published mouse model accurately depicts the genetic cause of PDX1-MODY in human patients. Methods: Using CRISPR-Cas9 technology, we generated the first mouse model carrying one of the most prevalent pathological PDX1 point mutation found in human patients, P33T, and conducted an 18-week in vivo phenotyping experiment assessing homozygous PDX1P33T and wild type littermates on both chow and high fat diet (HFD). Additionally, transcriptomic and proteomic analyses were performed on isolated pancreatic islets. Islet architecture was investigated via fluorescent microscopy. Result: Contrary to expectations, our comprehensive phenotypic analysis of the mouse model carrying the homozygous PDX1P33T point mutation revealed no significant differences in metabolic parameters compared to wild-type controls, and no pathological outcomes were observed as seen in human patients. Notably, male PDX1P33T mice exhibited an increase in islet size and number on chow diet but failed to adapt respectively on HFD. Discussion: Our work indicates substantial differences between mouse and human PDX1 function in the pancreas. Further refinement of animal models is necessary to better elucidate the pathophysiology of PDX1-MODY. Ultimately, this study emphasizes the complexities involved in translating human pathologies to animal models, serving as a reminder that findings generated in mice may not always be easily translated to humans.
Project description:Maturity-onset Diabetes of the young (MODY) is an early-onset, autosomal dominant form of non-insulin dependent diabetes. Genetic diagnosis of MODY can transform patient management. Earlier data on the genetic predisposition to MODY have come primarily from familial studies in populations of European origin. Using next generation sequencing, we carried out a comprehensive genomic analysis of 289 individuals from India that included 152 clinically diagnosed MODY cases to identify variants in known MODY genes. Our findings report that HNF1A and ABCC8 are among the most frequently mutated MODY genes in south India.
Project description:Pancreatic b-cell failure in type 2 diabetes is associated with functional abnormalities of insulin secretion and deficits of b-cell mass. It’s unclear how one begets the other. We have shown that loss of b-cell mass can be ascribed to impaired FoxO1 function in different models of diabetes. Here we show that ablation of the three FoxO genes (1, 3a, and 4) in mature b-cells results in early-onset, maturity onset diabetes of the young (MODY)-like diabetes, with signature abnormalities of the MODY networks of Hnf4a, Hnf1a, and Pdx1. Transcriptome and functional analyses reveal that FoxO-deficient b-cells are metabolically inflexible, i.e., they preferentially utilize lipids rather than carbohydrates as source of acetyl-CoA for mitochondrial oxidative phosphorylation. This results in impaired ATP generation, and reduced Ca2+-dependent insulin secretion. When viewed in the context of prior data illustrating a role of FoxO1 in b-cell dedifferentiation, the present findings define a seamless FoxO-dependent mechanism linking the twin abnormalities of b-cell function in diabetes. We used microarrays to detail the change of gene expression in pancreatic beta cells after knocking out FoxO1,3 and 4. Primary islets were isolated from pancretic beta cell- specific triple FoxO(1,3, and 4) KO and their littermates control (WT) mice. Gene expression was analyzed by microarray.
Project description:Introduction: Maturity-onset Diabetes of the Young (MODY) is a rare form of diabetes and arises from mutations in key regulatory genes of the pancreatic beta-cell, leading to their functional impairment and early-onset diabetes. Research into PDX1-MODY, a form of MODY caused by mutations in the PDX1 gene, enhances understanding of gene-specific mechanisms underlying glucose dysregulation and provides insights into possible approaches to restore normal metabolic function. However, no currently published mouse model accurately depicts the genetic cause of PDX1-MODY in human patients. Methods: Using CRISPR-Cas9 technology, we generated the first mouse model carrying one of the most prevalent pathological PDX1 point mutation found in human patients, P33T, and conducted an 18-week in vivo phenotyping experiment assessing homozygous PDX1P33T and wild-type littermates on both chow and high fat diet (HFD). Additionally, transcriptomic and proteomic analyses were performed on isolated pancreatic islets. Islet architecture was investigated via fluorescent microscopy. Result: Contrary to expectations, our comprehensive phenotypic analysis of the mouse model carrying the homozygous PDX1P33T point mutation revealed no significant differences in metabolic parameters compared to wild-type controls, and no pathological outcomes were observed as seen in human patients. Notably, male PDX1P33T mice exhibited an increase in islet size and number on chow diet but failed to adapt respectively on HFD. Discussion: Our work indicates substantial differences between mouse and human PDX1 function in the pancreas. Further refinement of animal models is necessary to better elucidate the pathophysiology of PDX1-MODY. Ultimately, this study emphasizes the complexities involved in translating human pathologies to animal models, serving as a reminder that findings generated in mice may not always be easily translated to humans.
Project description:Diabetes is a complex genetic disease affecting millions of people worldwide. A common monogenic form of diabetes is glucokinase (GCK) maturity-onset diabetes of the young (GCK-MODY), which is caused by heterozygous inactivating variants in the gene encoding GCK. GCK catalyzes the phosphorylation of glucose and is known as the pancreatic glucose sensor. Patients with GCK-MODY, in contrast to other diabetics, often do not require treatment but are frequently misdiagnosed and treated unnecessarily. Genetic testing can prevent this, but is hampered by the challenge of interpreting genetic variants. To address this challenge, we generated a comprehensive map of human GCK variant activity. The activity map includes 97% of the possible missense and nonsense variants and correlate with in vitro catalytic efficiency, fasting glucose levels in patients and evolutionary conservation analysis. Activity scores include both hyper- and hypoactive variants.
Project description:A strong association of the gain-of-function mutation in the TALK-1 K+ channel (p.L114P) with maturity-onset diabetes of the young (MODY) was recently reported in two distinct families. TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion (GSIS). KCNK16, the gene that encodes TALK-1, is the most abundant and β-cell–restricted K+ channel transcript and KCNK16 locus is strongly associated to type-2 diabetes. To investigate the impact of TALK-1-L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the TALK-1-L114P mutation was generated. Heterozygous and homozygous TALK-1-L114P mice exhibit increased neonatal lethality in the C57BL/6J and the CD-1(ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous TALK-1-L114P neonates due to lack of GSIS and can be reduced with insulin treatment. TALK-1-L114P drastically increases whole-cell β-cell K+ currents resulting in blunted glucose-stimulated Ca2+ entry and a complete loss of glucose-induced Ca2+ oscillations. Thus, adult TALK-1-L114P mice have reduced GSIS and plasma insulin levels, which significantly impairs glucose homeostasis. Taken together, this study shows that the MODY-associated TALK-1-L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by altering islet hormone secretion during development. These data strongly suggest that TALK-1 is an islet-restricted target for the treatment for diabetes
Project description:Mutations in several transcription factors lead to a subtype of type 2 diabetes called maturity-onset diabetes of the young (MODY), which are characterized by autosomal dominant inheritance, an early age of disease onset, and development of marked hyperglycemia with a progressive impairment in insulin secretion (Shih and Stoffel, 2002). The most frequent form of MODY is caused by mutations in the gene encoding hepatocyte nuclear factor-1a (HNF-1a, TCF1). Mutant mice with loss of Tcf1 function as well as transgenic mice expressing a naturally occurring dominant-negative form of human TCF1(P291fsinsC) in pancreatic beta cells develop progressive hyperglycemia due to impaired glucose-stimulated insulin secretion (Hagenfeldt-Johansson et al., 2001; Yamagata et al., 2002). Importantly, these mice exhibit a progressive reduction in beta cell number, proliferation rate, and pancreatic insulin content. These data indicate that Tcf-1 target genes are also required for maintenance of normal beta cell mass. In this study we sought to identify target genes of Tcf-1 that may be responsible of mediating beta cell growth by comparing gene expression profiles of Tcf-1 knock-out and wild-type littermates in isolated pancreatic islets.
Project description:Pancreatic b-cell failure in type 2 diabetes is associated with functional abnormalities of insulin secretion and deficits of b-cell mass. It’s unclear how one begets the other. We have shown that loss of b-cell mass can be ascribed to impaired FoxO1 function in different models of diabetes. Here we show that ablation of the three FoxO genes (1, 3a, and 4) in mature b-cells results in early-onset, maturity onset diabetes of the young (MODY)-like diabetes, with signature abnormalities of the MODY networks of Hnf4a, Hnf1a, and Pdx1. Transcriptome and functional analyses reveal that FoxO-deficient b-cells are metabolically inflexible, i.e., they preferentially utilize lipids rather than carbohydrates as source of acetyl-CoA for mitochondrial oxidative phosphorylation. This results in impaired ATP generation, and reduced Ca2+-dependent insulin secretion. When viewed in the context of prior data illustrating a role of FoxO1 in b-cell dedifferentiation, the present findings define a seamless FoxO-dependent mechanism linking the twin abnormalities of b-cell function in diabetes. We used microarrays to detail the change of gene expression in pancreatic beta cells after knocking out FoxO1,3 and 4.
2014-08-20 | GSE60505 | GEO
Project description:MODY related gene sequencing in Bangladeshi young with diabetes