Endocrinologies
Abstract
Type 2 diabetes (T2D) is caused by insufficient insulin secretion from pancreatic β-cells. To identify candidates contributing to T2D pathophysiology, we studied human pancreatic islets from ~300 individuals. We found 395 differentially expressed genes (DEGs) in islets from individuals with T2D, including, to our knowledge, novel (OPRD1, PAX5, TET1) and previously identified (CHL1, GLRA1, IAPP) candidates. A third of the identified islet expression changes may predispose to diabetes, as they associated with HbA1c in individuals not previously diagnosed with T2D. Most DEGs were expressed in human β-cells based on single-cell RNA-sequencing data. Additionally, DEGs displayed alterations in open chromatin and associated with T2D-SNPs. Mouse knock-out strains demonstrated that T2D-associated candidates regulate glucose homeostasis and body composition in vivo. Functional validation showed that mimicking T2D-associated changes for OPRD1, PAX5, and SLC2A2 impaired insulin secretion. Impairments in Pax5-overexpressing β-cells were due to severe mitochondrial dysfunction. Finally, we discovered PAX5 as a potential transcriptional regulator of many T2D-associated DEGs in human islets. Overall, we identified molecular alterations in human pancreatic islets contributing to β-cell dysfunction in T2D pathophysiology.
Authors
Karl Bacos, Alexander Perfilyev, Alexandros Karagiannopoulos, Elaine Cowan, Jones K. Ofori, Ludivine Bertonnier-Brouty, Tina Rönn, Andreas Lindqvist, Cheng Luan, Sabrina Ruhrmann, Mtakai Ngara, Åsa Nilsson, Sevda Gheibi, Claire L. Lyons, Jens O. Lagerstedt, Mohammad Barghouth, Jonathan L.S. Esguerra, Petr Volkov, Malin Fex, Hindrik Mulder, Nils Wierup, Ulrika Krus, Isabella Artner, Lena Eliasson, Rashmi B. Prasad, Luis Rodrigo Cataldo, Charlotte Ling
Abstract
Insulin and IGF-1 receptors (IR/IGF1R) are highly homologous and share similar signaling systems, but each has a unique physiological role, with IR primarily regulating metabolic homeostasis and IGF1R regulating mitogenic control and growth. Here, we showed that replacement of a single amino acid at position 973, just distal to the NPEY motif in the intracellular juxtamembrane region, from leucine, which is highly-conserved in IRs, to phenylalanine, the highly-conserved homologous residue in IGF1Rs, resulted in decreased IRS-1-PI3K-Akt-mTORC1 signaling and increased of Shc-Gab1-MAPK-cell cycle signaling. As a result, cells expressing L973F-IR exhibited decreased insulin-induced glucose uptake, increased cell growth and impaired receptor internalization. Mice with knockin of the L973F-IR showed similar alterations in signaling in vivo, and this leaded to decreased insulin sensitivity, a modest increase in growth and decreased weight gain when challenged with high-fat diet. Thus, leucine973 in the juxtamembrane region of the IR acts as a crucial residue differentiating IR signaling from IGF1R signaling.
Authors
Hirofumi Nagao, Weikang Cai, Bruna Brasil Brandão, Nicolai J. Wewer Albrechtsen, Martin Steger, Arijeet K. Gattu, Hui Pan, Jonathan M. Dreyfuss, F. Thomas Wunderlich, Matthias Mann, C. Ronald Kahn
Abstract
Disorders of isolated mineralocorticoid deficiency causing potentially life-threatening salt-wasting crisis early in life have been associated with gene variants of aldosterone biosynthesis or resistance, but in some patients no such variants are found. WNT/β-catenin signaling is crucial for differentiation and maintenance of the aldosterone producing adrenal zona glomerulosa (zG). We describe a highly consanguineous family with multiple perinatal deaths or infants presenting at birth with failure to thrive, severe salt-wasting crises associated with isolated hypoaldosteronism, nail anomalies, short stature, and deafness. Whole exome sequencing revealed a homozygous splice variant in the R-SPONDIN receptor LGR4 gene (c.618-1G>C) regulating WNT signaling. The resulting transcripts affected protein function and stability, and resulted in loss of Wnt/β-catenin signaling in vitro. The impact of LGR4 inactivation was analyzed by adrenal cortex specific ablation of Lgr4, using Lgr4Flox/Flox mated with Sf1:Cre mice. Inactivation of Lgr4 within the adrenal cortex in the mouse model caused decreased WNT signaling, aberrant zonation with deficient zG and reduced aldosterone production. Thus, human LGR4 mutations establish a direct link between LGR4 inactivation and decreased canonical WNT signaling with abnormal zG differentiation and endocrine function. Therefore, variants in WNT signaling and its regulators should systematically be considered in familial hyperreninemic hypoaldosteronism.
Authors
Cécily Lucas, Kay-Sara Sauter, Michael Steigert, Delphine Mallet, James Wilmouth Jr., Julie Olabe, Ingrid Plotton, Yves Morel, Daniel Aeberli, Franca Wagner, Hans Clevers, Amit V. Pandey, Pierre Val, Florence Roucher-Boulez, Christa E. Fluck
Abstract
Multiple genetic loci have been reported for progeroid syndromes. However, the molecular defects in some extremely rare forms of progeria have yet to be elucidated. Here we report a 21-year-old man of Chinese origin who had a novel autosomal recessive form of progeria, characterized by severe dwarfism, mandibular hypoplasia, hyperopia and partial lipodystrophy. Analyses of exome sequencing data of the entire family revealed only one rare homozygous missense variant, (c.86C>T; p.Pro29Leu), in TOMM7 in the proband, while the parents and two unaffected siblings were heterozygous for the variant. TOMM7, a nuclear gene, encodes a translocase in the outer mitochondrial membrane. The TOMM complex constitutes the outer membrane pore for import of several preproteins into mitochondria. Proteomics analyses of mitochondria from cultured fibroblasts of the proband, as compared to control fibroblasts, revealed increases in several proteins involved in oxidative phosphorylation, but reduced abundance of proteins involved in the phospholipid metabolism. We also observed elevated basal and maximal oxygen consumption rates in the fibroblasts from the proband as compared to control fibroblasts. We conclude that altered mitochondrial protein import due to loss of function bi-allelic variant in TOMM7 can cause severe growth retardation and progeroid features.
Authors
Abhimanyu Garg, Wee-Teik Keng, Zhenkang Chen, Adwait Amod Sathe, Chao Xing, Pavithira Devi Kailasam, Yanqiu Shao, Nicholas P. Lesner, Claire B. Llamas, Anil K. Agarwal, Prashant Mishra
Abstract
As a highly regenerative organ, the intestine is a promising source for cellular reprogramming to replace lost pancreatic β-cells in diabetes. Gut enterochromaffin cells can be converted to insulin-producing cells by FoxO1 ablation, but their numbers are limited. In this study we report that insulin-immunoreactive cells with Paneth/goblet cell features are present in human fetal intestine. Accordingly, lineage tracing experiments show that upon genetic or pharmacologic FoxO1 ablation the Paneth/goblet lineage can also undergo conversion to the insulin lineage. We designed a screening platform in gut organoids to accurately quantitate β-like cell reprogramming and fine-tune a combination treatment to increase the efficiency of the conversion process in mice and human adult intestinal organoids. We identified a triple blockade of FOXO1, Notch, and TGFβ that, when tested in insulin-deficient STZ or NOD diabetic animals resulted in near-normalization of glucose levels, associated with the generation of intestinal insulin-producing cells. The findings illustrate a therapeutic approach to replace insulin treatment in diabetes.
Authors
Wen Du, Junqiang Wang, Taiyi Kuo, Liheng Wang, Wendy M. McKimpson, Jinsook Son, Hitoshi Watanabe, Takumi Kitamoto, Yun-Kyoung Lee, Remi J. Creusot, Lloyd E. Ratner, Kasi McCune, Ya-Wen Chen, Brendan H. Grubbs, Matthew E. Thornton, Jason Fan, Nishat Sultana, Bryan S. Diaz, Iyshwarya Balasubramanian, Nan Gao, Sandro Belvedere, Domenico Accili
Abstract
BACKGROUND Hypoactive sexual desire disorder (HSDD) is characterized by a persistent deficiency of sexual fantasies and desire for sexual activity, causing marked distress and interpersonal difficulty. It is the most prevalent female sexual health problem globally, affecting approximately 10% of women, but has limited treatment options. Melanocortin 4 receptor (MC4R) agonists have emerged as a promising therapy for women with HSDD, through unknown mechanisms. Studying the pathways involved is crucial for our understanding of normal and abnormal sexual behavior.METHODS Using psychometric, functional neuroimaging, and hormonal analyses, we conducted a randomized, double-blinded, placebo-controlled, crossover clinical study to assess the effects of MC4R agonism compared with placebo on sexual brain processing in 31 premenopausal heterosexual women with HSDD.RESULTS MC4R agonism significantly increased sexual desire for up to 24 hours after administration compared with placebo. During functional neuroimaging, MC4R agonism enhanced cerebellar and supplementary motor area activity and deactivated the secondary somatosensory cortex, specifically in response to visual erotic stimuli, compared with placebo. In addition, MC4R agonism enhanced functional connectivity between the amygdala and the insula during visual erotic stimuli compared with placebo.CONCLUSION These data suggest that MC4R agonism enhanced sexual brain processing by reducing self-consciousness, increasing sexual imagery, and sensitizing women with HSDD to erotic stimuli. These findings provide mechanistic insight into the action of MC4R agonism in sexual behavior and are relevant to the ongoing development of HSDD therapies and MC4R agonist development more widely.TRIAL REGISTRATION ClinicalTrials.gov NCT04179734.FUNDING This is an investigator-sponsored study funded by AMAG Pharmaceuticals Inc., the Medical Research Council (MRC) (MR/T006242/1), and the National Institute for Health Research (NIHR) (CS-2018-18-ST2-002 and RP-2014-05-001).
Authors
Layla Thurston, Tia Hunjan, Edouard G. Mills, Matthew B. Wall, Natalie Ertl, Maria Phylactou, Beatrice Muzi, Bijal Patel, Emma C. Alexander, Sofiya Suladze, Manish Modi, Pei C. Eng, Paul A. Bassett, Ali Abbara, David Goldmeier, Alexander N. Comninos, Waljit S. Dhillo
Abstract
BACKGROUND. Cytochrome P450 Family 8 Subfamily B Member 1 (CYP8B1) generates 12α-hydroxylated bile acids (BAs) which were associated with insulin resistance in humans. METHODS. To determine if reduced CYP8B1 activity improves insulin sensitivity, we sequenced CYP8B1 in individuals without diabetes and identified carriers of complete loss-of-function (CLOF) mutations utilizing functional assays. RESULTS. Mutation carriers had lower plasma 12α-hydroxylated:non-12α-hydroxylated BA and cholic acid (CA):chenodeoxycholic acid (CDCA) ratios compared to age-, gender- and BMI-matched controls. During insulin clamps, hepatic glucose production was suppressed to a similar magnitude by insulin, but glucose infusion rates to maintain euglycemia were higher in mutation carriers, indicating increased peripheral insulin sensitivity. Consistently, a polymorphic CLOF CYP8B1 mutation associated with lower fasting insulin in the AMP-T2D-GENES study. Exposure of primary human muscle cells to carrier CA:CDCA ratios demonstrated increased FOXO1 activity, and upregulation of both insulin signaling and glucose uptake, which were mediated by increased CDCA. Inhibition of FOXO1 attenuated the CDCA-mediated increase in muscle insulin signaling and glucose uptake. We find that reduced CYP8B1 activity associates with increased insulin sensitivity in humans. CONCLUSION. Our findings suggest that increased circulatory CDCA due to reduced CYP8B1 activity increases skeletal muscle insulin sensitivity, contributing to increased whole-body insulin sensitization. FUNDING. This study was funded by BMRC/NMRC Bench and Bedside grant (BnB13Dec011) to HCT and RRS.
Authors
Shiqi Zhong, Raphael Chevre, David Castaño Mayan, Maria Corlianò, Blake J. Cochran, Kai Ping Sem, Theo H. van Dijk, Jianhe Peng, Liang Juin Tan, Siddesh V. Hartimath, Boominathan Ramasamy, Peter Cheng, Albert K. Groen, Folkert Kuipers, Julian L. Goggi, Chester Drum, Rob M. van Dam, Ru-San Tan, Kerry-Anne Rye, Michael R. Hayden, Ching-Yu Cheng, Shaji Chacko, Jason Flannick, Xueling Sim, Hong Chang Tan, Roshni R. Singaraja
Abstract
BACKGROUND. Studies in cell cultures and rodents suggest that toll-like receptor (TLR)4 is involved in the pathogenesis of insulin resistance, but direct data in humans are limited. We tested the hypothesis that pharmacologic blockade of TLR4 with the competitive inhibitor eritoran would improve insulin resistance in humans. METHODS. In Protocol I, 10 lean, healthy subjects received the following 72-h intravenous (I.V.) infusions in a randomized crossover design: saline (30 ml/h)+vehicle; Intralipid® (30 ml/h)+vehicle; or Intralipid® (30 ml/h)+eritoran (12 mg I.V. every 12 h). In Protocol II, 9 obese, non-diabetic subjects received eritoran (12 mg I.V. every 12 h) or vehicle for 72 h, also in a randomized crossover design. The effects of eritoran were assessed with a euglycemic, hyperinsulinemic clamp. RESULTS. In Protocol I, lipid infusion significantly decreased peripheral insulin sensitivity (M value) by 14% and increased fasting plasma glucose (FPG), fasting plasma insulin (FPI) and HOMA insulin resistance index (HOMA-IR) by 7%, 22%, and 26%, respectively. Eritoran did not prevent lipid-induced alterations in these metabolic parameters. Eritoran also failed to improve any baseline metabolic parameters (M, FPG, FPI, HOMA-IR) in obese, insulin-resistant subjects (Protocol II). CONCLUSIONS. Acute TLR4 inhibition with eritoran did not protect against lipid-induced insulin resistance. Short-term eritoran administration also failed to improve obesity-associated insulin resistance. These data do not support a role for TLR4 in insulin resistance. Future studies with a different class of TLR4 inhibitors, longer drug exposure, and/or lipid-enhancing interventions richer in saturated fats may be needed to further clarify the role of TLR4 on metabolic dysfunction in humans. TRIAL REGISTRATIONS. ClinicalTrials.gov NCT02321111, NCT02267317 FUNDING. NIH grants R01DK080157, P30AG044271, P30AG013319 and UL1TR002645.
Authors
Hanyu Liang, Nattapol Sathavarodom, Claudia Colmenares, Jonathan Gelfond, Sara E. Espinoza, Vinutha Ganapathy, Nicolas Musi
Abstract
Insulin resistance is a fundamental pathogenic factor that characterizes various metabolic disorders, including obesity and type 2 diabetes. Adipose tissue contributes to the development of obesity-related insulin resistance through increased release of fatty acids, altered adipokine secretion, and/or macrophage infiltration and cytokine release. Here, we aimed to analyze the participation of the cyclin-dependent kinase 4 (CDK4) in adipose tissue biology. We determined that white adipose tissue (WAT) from CDK4-deficient mice exhibits impaired lipogenesis and increased lipolysis. Conversely, lipolysis was decreased and lipogenesis was increased in mice expressing a mutant hyperactive form of CDK4 (CDK4R24C). We performed a global kinome analysis and found that mice lacking Cdk4 had impaired insulin signaling in the adipose tissue. Interestingly, our results demonstrated that insulin activates the cyclin D3-CDK4 complex, which, in turn, phosphorylates the insulin receptor substrate 2 (IRS2) at the Ser 388, likely creating a positive feedback loop to maintain adipocyte insulin signaling. Furthermore, we found that CCND3 expression and IRS2 serine 388 phosphorylation are increased in human obese subjects. Together, our results demonstrate that CDK4 is a major regulator of insulin signaling in WAT.
Authors
Sylviane Lagarrigue, Isabel C. Lopez-Mejia, Pierre-Damien Denechaud, Xavier Escoté, Judit Castillo-Armengol, Veronica Jimenez, Carine Chavey, Albert Giralt, Qiuwen Lai, Lianjun Zhang, Laia Martinez-Carreres, Brigitte Delacuisine, Jean-Sébastien Annicotte, Emilie Blanchet, Sébastien Huré, Anna Abella, Francisco J. Tinahones, Joan Vendrell, Pierre Dubus, Fatima Bosch, C. Ronald Kahn, Lluis Fajas
Abstract
Resistance to regeneration of insulin-producing pancreatic beta cells is a fundamental challenge for Type 1 and Type 2 diabetes. Recently, small molecule inhibitors of the kinase DYRK1A have proven effective in inducing adult human beta cells to proliferate, but their detailed mechanism of action is incompletely understood. We interrogated our human insulinoma and beta cell transcriptomic databases seeking to understand why beta cells in insulinomas proliferate, while normal beta cells do not. This search suggested the DREAM complex as a central regulator of quiescence in human beta cells. DREAM complex consists of a module of transcriptionally repressive proteins that assemble in response to DYRK1A kinase activity, thereby inducing and maintaining cellular quiescence. In the absence of DYRK1A, DREAM subunits reassemble into the pro-proliferative MMB complex. Here we demonstrate that small molecule DYRK1A inhibitors induce human beta cells to replicate by converting the repressive DREAM complex to its pro-proliferative MMB conformation.
Authors
Peng Wang, Esra Karakose, Carmen Argmann, Huan Wang, Metodi Balev, Rachel I. Brody, Hembly G. Rivas, Xinyue Liu, Olivia Wood, Hongtao Liu, Lauryn Choleva, Dan Hasson, Emily Bernstein, Joao A. Paulo, Donald K. Scott, Luca Lambertini, James A. DeCaprio, Andrew F. Stewart.
Copyright © 2023 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)