Endocrinology
Abstract
Reproduction is safeguarded by multiple, often cooperative regulatory networks. Kisspeptin signaling, via KISS1R, plays a fundamental role in reproductive control, primarily by regulation of hypothalamic GnRH neurons. We disclose herein a pathway for direct kisspeptin actions in astrocytes that contributes to central reproductive modulation. Protein-protein-interaction and ontology analyses of hypothalamic proteomic profiles after kisspeptin stimulation revealed that glial/astrocyte markers are regulated by kisspeptin in mice. This glial-kisspeptin pathway was validated by the demonstrated expression of Kiss1r in mouse astrocytes in vivo and astrocyte cultures from humans, rats and mice, where kisspeptin activated canonical intracellular signaling-pathways. Cellular co-expression of Kiss1r with the astrocyte markers, GFAP and S100-β, occurred in different brain regions, with higher percentage in Kiss1- and GnRH-enriched areas. Conditional ablation of Kiss1r in GFAP-positive cells, in the G-KiRKO mouse, altered gene expression of key factors in PGE2 synthesis in astrocytes, and perturbed astrocyte-GnRH neuronal appositions, as well as LH responses to kisspeptin and LH pulsatility, as surrogate marker of GnRH secretion. G-KiRKO mice also displayed changes in reproductive responses to metabolic stress induced by high-fat diet, affecting female pubertal onset, estrous cyclicity and LH-secretory profiles. Our data unveil a non-neuronal pathway for kisspeptin actions in astrocytes, which cooperates in fine-tuning the reproductive axis and its responses to metabolic stress.
Authors
Encarnacion Torres, Giuliana Pellegrino, Melissa Granados-Rodríguez, Antonio C. Fuentes-Fayos, Inmaculada Velasco, Adrian Coutteau-Robles, Amandine Legrand, Marya Shanabrough, Cecilia Perdices-Lopez, Silvia Leon, Shel H. Yeo, Stephen M. Manchishi, Maria J. Sánchez-Tapia, Victor M. Navarro, Rafael Pineda, Juan Roa, Frederick Naftolin, Jesús Argente, Raúl M. Luque, Julie A. Chowen, Tamas L. Horvath, Vicent Prevot, Ariane Sharif, William H. Colledge, Manuel Tena-Sempere, Antonio Romero-Ruiz
Abstract
Pancreatic β-cell dysfunction is a key feature of type 2 diabetes, and novel regulators of insulin secretion are desirable. Here we report that the succinate receptor (SUCNR1) is expressed in β-cells and is up-regulated in hyperglycemic states in mice and humans. We found that succinate acts as a hormone-like metabolite and stimulates insulin secretion via a SUCNR1-Gq-PKC-dependent mechanism in human β-cells. Mice with β-cell-specific Sucnr1 deficiency exhibit impaired glucose tolerance and insulin secretion on a high-fat diet, indicating that SUCNR1 is essential for preserving insulin secretion in diet-induced insulin resistance. Patients with impaired glucose tolerance show an enhanced nutritional-related succinate response, which correlates with the potentiation of insulin secretion during intravenous glucose administration. These data demonstrate that the succinate/SUCNR1 axis is activated by high glucose and identify a GPCR-mediated amplifying pathway for insulin secretion relevant to the hyperinsulinemia of prediabetic states.
Authors
Joan Sabadell-Basallote, Brenno Astiarraga, Carlos Castaño, Miriam Ejarque, Maria Repollés-de-Dalmau, Ivan Quesada, Jordi Blanco, Catalina Nuñez-Roa, M-Mar Rodríguez-Peña, Laia Martínez, Dario F. De Jesus, Laura Marroqui, Ramon Bosch, Eduard Montanya, Francesc X. Sureda, Andrea Tura, Andrea Mari, Rohit N. Kulkarni, Joan Vendrell, Sonia Fernández-Veledo
Abstract
Just as the androgen receptor (AR), the estrogen receptor α (ERα) is expressed in the prostate and is thought to influence prostate cancer (PCa) biology. Yet, the incomplete understanding of ERα functions in PCa hinders our ability to fully comprehend its clinical relevance and restricts the repurposing of estrogen-targeted therapies for the treatment of this disease. Using two human PCa tissue microarray cohorts, we first demonstrated that nuclear ERα expression was heterogeneous among patients, being only detected in half of tumors. Positive nuclear ERα levels were correlated with disease recurrence, progression to metastatic PCa, and patient survival. Using in vitro and in vivo models of the normal prostate and PCa, bulk and single-cell RNA-Seq analyses revealed that estrogens partially mimic the androgen transcriptional response and induce specific biological pathways linked to proliferation and metabolism. Bioenergetic flux assays and metabolomics confirmed the regulation of cancer metabolism by estrogens, supporting proliferation. Using cancer cell lines and patient-derived organoids, selective estrogen receptor modulators, a pure anti-estrogen, and genetic approaches impaired cancer cell proliferation and growth in an ERα-dependent manner. Overall, our study revealed that, when expressed, ERα functionally reprograms PCa metabolism, is associated with disease progression, and could be targeted for therapeutic purposes.
Authors
Camille Lafront, Lucas Germain, Gabriel H. Campolina-Silva, Cindy Weidmann, Line Berthiaume, Hélène Hovington, Hervé Brisson, Cynthia Jobin, Lilianne Frégeau-Proulx, Raul Cotau, Kevin Gonthier, Aurélie Lacouture, Patrick Caron, Claire Ménard, Chantal Atallah, Julie Riopel, Éva Latulippe, Alain Bergeron, Paul Toren, Chantal Guillemette, Martin Pelletier, Yves Fradet, Clémence Belleannée, Frédéric Pouliot, Louis Lacombe, Éric Lévesque, Étienne Audet-Walsh
Abstract
Authors
Gianfranco Di Giuseppe, Laura Soldovieri, Gea Ciccarelli, Pietro Manuel Ferraro, Giuseppe Quero, Francesca Cinti, Umberto Capece, Simona Moffa, Enrico Celestino Nista, Antonio Gasbarrini, Andrea Mari, Sergio Alfieri, Vincenzo Tondolo, Alfredo Pontecorvi, Jens Juul Holst, Andrea Giaccari, Teresa Mezza
Abstract
Early gestational loss occurs in approximately 20% of all clinically recognized human pregnancies and is an important cause of morbidity. Either embryonic or maternal defects can cause loss, but a functioning and receptive uterine endometrium is crucial for embryo implantation. We report that the switch/sucrose nonfermentable (SWI/SNF) remodeling complex containing polybromo-1 (PBRM1) and Brahma-related gene 1 (BRG1) is essential for implantation of the embryonic blastocyst on the wall of the uterus in mice. Although preimplantation development is unaffected, conditional ablation of Pbrm1 in uterine stromal cells disrupts progesterone pathways and uterine receptivity. Heart and neural crest derivatives expressed 2 (Hand2) encodes a basic helix-loop-helix (bHLH) transcription factor required for embryo implantation. We identify an enhancer of the Hand2 gene in stromal cells that requires PBRM1 for epigenetic histone modifications/coactivator recruitment and looping with the promoter. In Pbrm1cKO mice, perturbation of chromatin assembly at the promoter and enhancer sites compromises Hand2 transcription, adversely affects fibroblast growth factor signaling pathways, prevents normal stromal-epithelial crosstalk, and disrupts embryo implantation. The mutant female mice are infertile and provide insight into potential causes of early pregnancy loss in humans.
Authors
Qiliang Xin, Iris Feng, Guoyun Yu, Jurrien Dean
Abstract
In response to a meal, insulin drives hepatic glycogen synthesis to help regulate systemic glucose homeostasis. The mechanistic target of rapamycin complex 1 (mTORC1) is a well-established insulin target and contributes to the postprandial control of liver lipid metabolism, autophagy, and protein synthesis. However, its role in hepatic glucose metabolism is less understood. Here, we used metabolomics, isotope tracing, and mouse genetics to define a role for liver mTORC1 signaling in the control of postprandial glycolytic intermediates and glycogen deposition. We show that mTORC1 is required for glycogen synthase activity and glycogenesis. Mechanistically, hepatic mTORC1 activity promotes the feeding-dependent induction of Ppp1r3b, a gene encoding a phosphatase important for glycogen synthase activity whose polymorphisms are linked to human diabetes. Re-expression of Ppp1r3b in livers lacking mTORC1 signaling enhances glycogen synthase activity and restores postprandial glycogen content. mTORC1-dependent transcriptional control of Ppp1r3b is facilitated by FOXO1, a well characterized transcriptional regulator involved in the hepatic response to nutrient intake. Collectively, we identify a role for mTORC1 signaling in the transcriptional regulation of Ppp1r3b and the subsequent induction of postprandial hepatic glycogen synthesis.
Authors
Kahealani Uehara, Won Dong Lee, Megan Stefkovich, Dipsikha Biswas, Dominic Santoleri, Anna E. Garcia Whitlock, William J. Quinn III, Talia N. Coopersmith, Kate Townsend Creasy, Daniel J. Rader, Kei Sakamoto, Joshua D. Rabinowitz, Paul M. Titchenell
Abstract
Ghrelin exerts key effects on islet hormone secretion to regulate blood glucose levels. Here, we sought to determine whether ghrelin’s effects on islets extend to the alteration of islet size and β cell mass. We demonstrate that reducing ghrelin — by ghrelin gene knockout (GKO), conditional ghrelin cell ablation, or high-fat diet (HFD) feeding — was associated with increased mean islet size (up to 62%), percentage of large islets (up to 854%), and β cell cross-sectional area (up to 51%). In GKO mice, these effects were more apparent in 10- to 12-week-old mice than in 4-week-old mice. Higher β cell numbers from decreased β cell apoptosis drove the increase in β cell cross-sectional area. Conditional ghrelin cell ablation in adult mice increased the β cell number per islet by 40% within 4 weeks. A negative correlation between islet size and plasma ghrelin in HFD-fed plus chow-fed WT mice, together with even larger islet sizes in HFD-fed GKO mice than in HFD-fed WT mice, suggests that reduced ghrelin was not solely responsible for diet-induced obesity–associated islet enlargement. Single-cell transcriptomics revealed changes in gene expression in several GKO islet cell types, including upregulation of Manf, Dnajc3, and Gnas expression in β cells, which supports decreased β cell apoptosis and/or increased β cell proliferation. These effects of ghrelin reduction on islet morphology might prove useful when designing new therapies for diabetes.
Authors
Deepali Gupta, Avi W. Burstein, Dana C. Schwalbe, Kripa Shankar, Salil Varshney, Omprakash Singh, Subhojit Paul, Sean B. Ogden, Sherri Osborne-Lawrence, Nathan P. Metzger, Corine P. Richard, John N. Campbell, Jeffrey M. Zigman
Abstract
Pancreatic beta-cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair beta-cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion are similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on beta-cell mRNA translation. Prior to induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also of mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex-vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our study uncovered a translational regulatory circuit during beta-cell glucose toxicity that impairs expression of proteins with critical roles in beta-cell function.
Authors
Abigael Cheruiyot, Jennifer Hollister-Lock, Brooke A. Sullivan, Hui Pan, Jonathan M. Dreyfuss, Susan Bonner-Weir, Jean E. Schaffer
Abstract
Half of all men with advanced prostate cancer (PCa) inherit at least 1 copy of an adrenal-permissive HSD3B1 (1245C) allele, which increases levels of 3β-hydroxysteroid dehydrogenase 1 (3βHSD1) and promotes intracellular androgen biosynthesis. Germline inheritance of the adrenally permissive allele confers worse outcomes in men with advanced PCa. We investigated whether HSD3B1 (1245C) drives resistance to combined androgen deprivation and radiotherapy. Adrenally permissive 3βHSD1 enhanced resistance to radiotherapy in PCa cell lines and xenograft models engineered to mimic the human adrenal/gonadal axis during androgen deprivation. The allele-specific effects on radiosensitivity were dependent on availability of DHEA, the substrate for 3βHSD1. In lines expressing the HSD3B1 (1245C) allele, enhanced expression of DNA damage response (DDR) genes and more rapid DNA double-strand break (DSB) resolution were observed. A correlation between androgen receptor (AR) expression and increased DDR gene expression was confirmed in 680 radical prostatectomy specimens. Treatment with the nonsteroidal antiandrogen enzalutamide reversed the resistant phenotype of HSD3B1 (1245C) PCa in vitro and in vivo. In conclusion, 3βHSD1 promotes prostate cancer resistance to combined androgen deprivation and radiotherapy by upregulating DNA DSB repair. This work supports prospective validation of early combined androgen blockade for high-risk men harboring the HSD3B1 (1245C) allele.
Authors
Shinjini Ganguly, Zaeem Lone, Andrew Muskara, Jarrell Imamura, Aimalie Hardaway, Mona Patel, Mike Berk, Timothy D. Smile, Elai Davicioni, Kevin L. Stephans, Jay Ciezki, Christopher J. Weight, Shilpa Gupta, Chandana A. Reddy, Rahul D. Tendulkar, Abhishek A. Chakraborty, Eric A. Klein, Nima Sharifi, Omar Y. Mian
Abstract
Autoimmune polyendocrine syndrome type 1 (APS-1) is caused by mutations in the autoimmune regulator (AIRE) gene. Most patients present with severe chronic mucocutaneous candidiasis and organ-specific autoimmunity from early childhood, but the clinical picture is highly variable. AIRE is crucial for negative selection of T cells, and scrutiny of different patient mutations has previously highlighted many of its molecular mechanisms. In patients with a milder adult-onset phenotype sharing a mutation in the canonical donor splice site of intron 7 (c.879+1G>A), both the predicted altered splicing pattern with loss of exon 7 (AireEx7–/–) and normal full-length AIRE mRNA were found, indicating leaky rather than abolished mRNA splicing. Analysis of a corresponding mouse model demonstrated that the AireEx7–/– mutant had dramatically impaired transcriptional capacity of tissue-specific antigens in medullary thymic epithelial cells but still retained some ability to induce gene expression compared with the complete loss-of-function AireC313X–/– mutant. Our data illustrate an association between AIRE activity and the severity of autoimmune disease, with implications for more common autoimmune diseases associated with AIRE variants, such as primary adrenal insufficiency, pernicious anemia, type 1 diabetes, and rheumatoid arthritis.
Authors
Bergithe Eikeland Oftedal, Amund Holte Berger, Øyvind Bruserud, Yael Goldfarb, Andre Sulen, Lars Breivik, Alexander Hellesen, Shifra Ben-Dor, Rebecca Haffner-Krausz, Per M. Knappskog, Stefan Johansson, Anette S.B. Wolff, Eirik Bratland, Jakub Abramson, Eystein Sverre Husebye
Copyright © 2024 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)