Sexually dimorphic roles for the type 2 diabetes-associated C2cd4b gene in murine glucose homeostasis

• DOI: 10.1007/s00125-020-05350-x
• Publication Date: 2021-01-25T08:05:19Z
• Authors: S. Neda Mousavy G...; Bryn M. Owen; Steven J. Millership; Pauline Chabosseau; Grazia Pizza; Aida Martinez-San...; Emirhan Tasoez; Eleni Georgiadou; Ming Hu; Nicholas H. F. Fine; David A. Jacobson; Matthew T. Dickerson; Olof Idevall-Hagren; Alex Montoya; Holger Kramer; Zenobia Mehta; Dominic J. Withers; Nikolay Ninov; Paul J. Gadue; Fabian L. Cardena...; Céline Cruciani-G...; Christophe Magnan; Mark Ibberson; Isabelle Leclerc; Marianne Voz; Guy A. Rutter
• Keywords: Blood Glucose; Male; 0301 basic medicine; 570; Genotype; 610; Endocrinology and Diabetes; Glucose homeostasis; Weight Gain; Genome-wide association studies; Article; 1117 Public Health and Health Services; Endocrinology & Metabolism; 03 medical and health sciences; Animals; Biomarkers/blood; Blood Glucose/genetics; Blood Glucose/metabolism; Diabetes Mellitus, Type 2/genetics; Female; Follicle Stimulating Hormone/blood; Genotype; Homeostasis/genetics; Humans; Insulin/blood; Insulin-Secreting Cells/metabolism; Male; Mice, Inbred C57BL; Mice, Knockout; Nuclear Proteins/genetics; Phenotype; Pituitary Gland/metabolism; Sex Characteristics; Transcription Factors/genetics; Weight Gain; Zebrafish/blood; Zebrafish/genetics; Zebrafish Proteins/blood; Zebrafish Proteins/genetics; C2CD4A/B; Follicle-stimulating hormone; Genome-wide association studies; Glucose homeostasis; Type 2 diabetes; Insulin-Secreting Cells; Animals; Homeostasis; Humans; Insulin; Follicle-stimulating hormone; Mice, Knockout; Sex Characteristics; Science & Technology; Nuclear Proteins; Type 2 diabetes; 1103 Clinical Sciences; 3. Good health; [SDV] Life Sciences [q-bio]; Mice, Inbred C57BL; Phenotype; Diabetes Mellitus, Type 2; Pituitary Gland; Endokrinologi och diabetes; 1114 Paediatrics and Reproductive Medicine; Female; C2CD4A/B; Follicle Stimulating Hormone; Life Sciences & Biomedicine; Biomarkers; Transcription Factors

Abstract Aims/hypothesis Variants close to the VPS13C/C2CD4A/C2CD4B locus are associated with altered risk of type 2 diabetes in genome-wide association studies. While previous functional work has suggested roles for VPS13C and C2CD4A in disease development, none has explored the role of C2CD4B.

Methods CRISPR/Cas9-induced global C2cd4b-knockout mice and zebrafish larvae with c2cd4a deletion were used to study the role of this gene in glucose homeostasis. C2 calcium dependent domain containing protein (C2CD)4A and C2CD4B constructs tagged with FLAG or green fluorescent protein were generated to investigate subcellular dynamics using confocal or near-field microscopy and to identify interacting partners by mass spectrometry.

Results Systemic inactivation of C2cd4b in mice led to marked, but highly sexually dimorphic changes in body weight and glucose homeostasis. Female C2cd4b mice displayed unchanged body weight compared with control littermates, but abnormal glucose tolerance (AUC, p = 0.01) and defective in vivo, but not in vitro, insulin secretion (p = 0.02). This was associated with a marked decrease in follicle-stimulating hormone levels as compared with wild-type (WT) littermates (p = 0.003). In sharp contrast, male C2cd4b null mice displayed essentially normal glucose tolerance but an increase in body weight (p < 0.001) and fasting blood glucose (p = 0.003) after maintenance on a high-fat and -sucrose diet vs WT littermates. No metabolic disturbances were observed after global inactivation of C2cd4a in mice, or in pancreatic beta cell function at larval stages in C2cd4a null zebrafish. Fasting blood glucose levels were also unaltered in adult C2cd4a-null fish. C2CD4B and C2CD4A were partially localised to the plasma membrane, with the latter under the control of intracellular Ca2+. Binding partners for both included secretory-granule-localised PTPRN2/phogrin.

Conclusions/interpretation Our studies suggest that C2cd4b may act centrally in the pituitary to influence sex-dependent circuits that control pancreatic beta cell function and glucose tolerance in rodents. However, the absence of sexual dimorphism in the impact of diabetes risk variants argues for additional roles for C2CD4A or VPS13C in the control of glucose homeostasis in humans.

Data availability The datasets generated and/or analysed during the current study are available in the Biorxiv repository (www.biorxiv.org/content/10.1101/2020.05.18.099200v1). RNA-Seq (GSE152576) and proteomics (PXD021597) data have been deposited to GEO (www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE152576) and ProteomeXchange (www.ebi.ac.uk/pride/archive/projects/PXD021597) repositories, respectively.

Graphical abstract