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Male mice lacking the androgen receptor (AR) in islet β cells exhibit blunted glucose-stimulated insulin secretion (GSIS) , leading to hypoinsulinemia and hyperglycemia. We showed that dihydrotestosterone (DHT) activation of an extranuclear AR in β cells potentiates GSIS by amplifying the insulinotropic action of GLP-1 in mouse and human islets. To gain information on DHT-stimulated signaling networks promoting GSIS, we combined functional proteomics with highly selective pharmacological inhibitors in male human islets, and islets from genetic mouse models. We found that DHT-stimulated GSIS in human islets involved a signaling cascade including focal adhesion kinases, the nonreceptor tyrosine kinase SRC, phosphoinositide 3-kinase, and the activation of mTOR complex 2. To define the early network of AR interacting proteins, we performed DHT-stimulated AR immunoprecipitation in INS1 832/3 cells followed by mass spectrometry-based proteomics. We will discuss the AR interactome including: 1) adenylate cyclase-modulating G proteins Gαs and Gαi, cAMP-dependent PKA, and the cAMP-dependent protein LASP1 regulating actin-based cytoskeletal activities; 2) Actin cytoskeleton remodeling proteins promoting actin depolymerization, and 3) Vesicular maturation including the lysosomal vacuolar-type ATPase acidifying insulin secretory granules and the prohormone convertase 2 involved in proinsulin processing. Notably, GLP-1 addition to DHT decreased AR interaction with all these proteins and promoted AR interaction with microtubule motor proteins promoting vesicular transport, proteins involved in exocytic vesicle docking to the plasma membrane, as well as small GTPase activating proteins and guanine nucleotide exchange factors involved in actin remodeling, as well as vesicle trafficking. Together these experiments provide novel insights into the architecture of AR action in enhancing GSIS. Disclosure P.Mota de sa: None. M.Qadir: None. M.Blandino-rosano: None. J.Fan: None. W.Xu: None. E.Bernal-mizrachi: None. F.Mauvais-jarvis: Consultant; Mithra Pharmaceutical. Funding National Institutes of Health (DK107444 and DK074970) U.S. Department of Veterans Affairs Merit Award (BX003725)

Male mice with elimination of the androgen receptor (AR) in islet β cells (βARKO) exhibit blunted glucose-stimulated insulin secretion (GSIS) , leading to hypoinsulinemia and hyperglycemia. We showed that dihydrotestosterone (DHT) activation of an extranuclear AR in β cells potentiates GSIS by amplifying the insulinotropic action of islet-derived and exogenous GLP-1 via GLP-1R in mouse and human islets. Using electron microscopy, we observe that DHT increases the size of granules and the frequency of multivesicular granules, suggesting that DHT promotes multivesicular exocytosis. Using live β cell models expressing organelle-specific cAMP sensors and novel allosteric inhibitors in human islets, we show that DHT enhances the ability of GLP-1 to produce cAMP at the plasma membrane and endosomes and enhances islet GSIS via the bicarbonate (HCO3 -) sensor, soluble adenylate cyclase (sAC) . The end-products of glucose metabolism in the TCA cycle are CO2 and H2O, which is followed by rapid conversion of CO2 to HCO3 - and H+ by carbonic anhydrase (CA) . Therefore, CO2 production is translated to HCO3 - and specifically sensed by sAC. Bioenergetics analysis of DHT-stimulated respiration in mouse islets using a Seahorse Analyser revealed that DHT decreases glycolytic acidification and increases mitochondrial acidification (H+ efflux rate) , suggesting that DHT increases mitochondrial production of CO2 followed by conversion to HCO3 - and H+, allowing HCO3 - to stimulate sAC. We discuss experiments of single-cell transcriptomics, proteomics and metabolomics dissecting the impact of DHT on human islets glycolysis and mitochondrial CO2 production. Consistent with DHT increasing production of CO2 followed by conversion to HCO3 - by CA and activation of sAC, in cultured human male islets, the CA inhibitor acetazolamide blunted DHT-enhancement of GSIS. Together these experiments provide novel insights into the role of DHT action via an extranuclear AR in enhancing GSIS. Disclosure M.Qadir: None. D.Hodson: Other Relationship; Celtarys Research. F.Mauvais-jarvis: Consultant; Mithra Pharmaceutical. W.Xu: None. D.Nasteska: None. M.Bhondeley: None. P.Mota de sa: None. C.R.Evans: None. J.Buck: None. L.Levin: None. C.Burant: None. Funding National Institutes of Health (DK107444 and DK074970) U.S. Department of Veterans Affairs Merit Award (BX003725)

Testosterone (T) affects β-cell function in men and women. T is a prohormone that undergoes intracrine conversion in target tissues to the potent androgen dihydrotestosterone (DHT) via the enzyme 5α-reductase (5α-R) or to the active estrogen 17β-estradiol (E2) via the aromatase enzyme. Using male and female human pancreas sections, we show that the 5α-R type 1 isoform (SRD5A1) and aromatase are expressed in male and female β-cells. We show that cultured male and female human islets exposed to T produce DHT and downstream metabolites. In these islets, exposure to the 5α-R inhibitors finasteride and dutasteride inhibited T conversion into DHT. We did not detect T conversion into E2 from female islets. However, we detected T conversion into E2 in islets from two out of four male donors. In these donors, exposure to the aromatase inhibitor anastrozole inhibited E2 production. Notably, in cultured male and female islets, T enhanced glucose-stimulated insulin secretion (GSIS). In these islets, exposure to 5α-R inhibitors or the aromatase inhibitor both inhibited T enhancement of GSIS. In conclusion, male and female human islets convert T into DHT and E2 via the intracrine activities of SRD5A1 and aromatase. This process is necessary for T enhancement of GSIS.

We showed that the gonadal hormones estradiol and testosterone influence islet β-cell function and survival in a sex-specific manner via estrogen and androgen receptors expressed in islet β-cells. The progesterone receptor (PR) is a ligand-activated transcription factor and is believed to be involved in the β-cell adaptation to pregnancy. Leveraging public single-cell RNA-seq datasets we observe PR mRNA expression in α- β- and γ-cells in male and female human pancreatic endocrine cells. Using immunohistochemistry, we observe that, unlike in the uterus where PR is nuclear, PR is localized in the cytoplasm of β-cells in male and female human and mouse islets. We investigated the role of progesterone and PR in β-cell physiology in male and female mice with conditional deletion of PR in β-cells (βPRKO) by crossing PR-Lox/lox and MIP-Cre transgenic mice. Male βPRKO mice exhibited no alteration in glucose homeostasis on normal chow (NC) or following western-diet (WD)-induced insulin resistance and obesity compared to littermate PR-Lox/lox controls. Similarly, NC-fed female βPRKO mice exhibited no abnormality of glucose or insulin homeostasis compared to littermate PR-Lox/lox controls. However, during pregnancy or WD feeding, female βPRKO mice developed enhanced IP-glucose-stimulated insulin secretion, associated with improved IP glucose tolerance compared to littermate PR-Lox/lox controls. These results reveal that PR is a cytosolic receptor in β-cells, and suggest that in conditions of high insulin demand, such as pregnancy and diet-induced insulin resistance, elimination of PR action in β-cells of females improves the ability of β-cells to produce insulin and lowers blood glucose. PR may be involved in the pathogenesis of gestational diabetes. Disclosure P. Mota de sa: None. M. Qadir: None. F. Mauvais-jarvis: None. Funding National Institutes of Health (DK074970, DK107444); U.S. Department of Veterans Affairs (BX003725)

Testosterone (T) affects β cell function in men and women. T is a pro-hormone that undergoes intracrine conversion in target tissues to the potent androgen dihydrotestosterone (DHT) via the enzyme 5α-reductase (5α-R), or to the active estrogen 17β-estradiol (E2) via the aromatase enzyme. Using male and female human pancreas sections, we show that the 5α-R type1 isoform (SRD5A1) and aromatase are expressed in male and female β cells. We show that cultured male and female human islets exposed to T produce DHT and downstream metabolites. In these islets, exposure to the 5α-R inhibitors finasteride and dutasteride inhibited T conversion into DHT. We did not detect T conversion into E2 from female islets. However, we detected T conversion into E2 in islets from one out of four male donors. In this donor, exposure to the aromatase inhibitor anastrozole inhibited E2 production. Notably, in cultured male and female islets, T enhanced glucose-stimulated insulin secretion (GSIS). In these islets, exposure to 5α-R inhibitors or the aromatase inhibitor both inhibited T enhancement of GSIS. In conclusion, male and female human islets convert T into DHT and E2 via the intracrine activities of SRD5A1 and aromatase. This process is necessary for T enhancement of GSIS.