Two Novel Candidate Genes for Insulin Secretion Identified by Comparative Genomics of Multiple Backcross Mouse Populations

Abstract

To identify novel disease genes for type 2 diabetes (T2D) we generated two backcross populations of obese and diabetessusceptible New Zealand Obese (NZO/HI) mice with the two lean mouse strains 129P2/OlaHsd and C3HeB/FeJ. Subsequent wholegenome linkage scans revealed 30 novel quantitative trait loci (QTL) for T2D-associated traits. The strongest association with blood glucose [12 cM, logarithm of the odds (LOD) 13.3] and plasma insulin (17 cM, LOD 4.8) was detected on proximal chromosome 7 (designated Nbg7p, NZO blood glucose on proximal chromosome 7) exclusively in the NZOxC3H crossbreeding, suggesting that the causal gene is contributed by the C3H genome. Introgression of the critical C3H fragment into the genetic NZO background by generating recombinant congenic strains and metabolic phenotyping validated the phenotype. For the detection of candidate genes in the critical region (30-46 Mb), we used a combined approach of haplotype and gene expression analysis to search for C3H-specific gene variants in the pancreatic islets, which appeared to be the most likely target tissue for the QTL. Two genes, Atp4a and Pop4, fulfilled the criteria from our candidate gene approaches. The knockdown of both genes in MIN6 cells led to decreased glucosestimulated insulin secretion, indicating a regulatory role of both genes in insulin secretion, thereby possibly contributing to the phenotype linked to Nbg7p. In conclusion, our combined-and comparative-cross analysis approach has successfully led to the identification of two novel diabetes susceptibility candidate genes, and thus has been proven to be a valuable tool for the discovery of novel disease genes.

H+/K+ATPase Expression in the Larynx of Laryngopharyngeal Reflux and Laryngeal Cancer Patients

“…36,37 Gastric H+/K+ ATPase in human pancreas contributes to pancreatic exocrine secretion which is disrupted upon PPI treatment. 38,39 H+/K+ ATPase has also been reported to play a role in maintenance of airway epithelium and mucociliary transport. Recent studies in an in vivo model of airway mucociliated epithelium demonstrated the requirement of H+/K+ ATPase (ATP4A) expression for activation of Wnt signaling cascades that regulate differentiation of secretory and ciliated cells.…”

Decreased Expression of Cilia Genes in Pancreatic Islets as a Risk Factor for Type 2 Diabetes in Mice and Humans

“…The New Zealand Obese (NZO) mouse represents a model for polygenic T2D and obesity that closely resembles the human disease (Joost and Sch€ urmann, 2014). Recently, we discovered a number of quantitative trait loci (QTL) that participate in obesity and insulin resistance in NZO mice (Chadt et al, 2008;Schallschmidt et al, 2018;Scherneck et al, 2009;Vogel et al, 2009Vogel et al, , 2018 and, furthermore, identified some of the causal disease genes and their specific metabolic effects (e.g., Zfp69 and Ifi202b) (Chung et al, 2015;Stadion et al, 2018). In contrast, the C57BL/6 mouse, which lacks leptin, the B6.V-Lep ob/ob (B6-ob/ob) mouse develops severe obesity but is protected from diabetes by an adaptive beta-cell proliferation (Kleinert et al, 2018).…”

Identification of Novel Potential Type 2 Diabetes Genes Mediating β-Cell Loss and Hyperglycemia Using Positional Cloning

“…DBA mice carry an intact copy of Zfp69 , however, characterization of recombinant congenic mice excluded the possibility that Zfp69 is responsible for β-cell failure observed in Nidd/DBA mice, as Zfp69 is located outside of the smallest critical Nidd/DBA fragment (108.1–111.4 Mbp) inducing hyperglycemia. In addition to SJL, QTL for elevated blood glucose were identified on chromosome 4 from parallel NZO crosses with C3H and 129P2 ( Schallschmidt et al, 2018 ). The QTL derived from SJL, 129P2, and C3H were characterized not only by hyperglycemia but also by a lack of insulin, indicating that β-cell failure is underlying the diabetogenic effect of the QTL.…”

“…Haplogroup analysis was performed, as described ( Schallschmidt et al, 2018 ). In brief, mouse single nucleotide polymorphism (SNPs) were used from the Wellcome Trust Sanger Institute Database.…”