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Burgos-Gamez X, Morales-Castillo P, Fernandez-Mejia C. Maternal adaptations of the pancreas and glucose homeostasis in lactation and after lactation. Mol Cell Endocrinol 2023; 559:111778. [PMID: 36162635 DOI: 10.1016/j.mce.2022.111778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 09/04/2022] [Accepted: 09/13/2022] [Indexed: 02/03/2023]
Abstract
During lactation, the maternal physiology adapts to bear the nutritional requirements of the offspring. The exocrine and endocrine pancreas are central to nutrient handling, promoting digestion and metabolism. In concert with prolactin, insulin is a determinant factor for milk synthesis. The investigation of the pancreas during lactation has been scattered over several periods. The investigations that laid the foundation of lactating pancreatic physiology and glucose homeostasis were conducted in the decades of 1970-1980. With the development of molecular biology, newer studies have revealed the molecular mechanisms involved in the endocrine pancreas during breastfeeding. There has been a surge of information recently about unexpected changes in the pancreas at the end of the lactation period and after weaning. In this review, we aim to gather information on the changes in the pancreas and glucose homeostasis during and after lactation and discuss the outcomes derived from the current discoveries.
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Affiliation(s)
- Xadeni Burgos-Gamez
- Unidad de Genética de la Nutrición. Instituto de Investigaciones Biomédicas. Universidad Nacional Autónoma de México/ Instituto Nacional de Pediatría. Avenida del Iman#1, 4th floor, Mexico City, 04500, Mexico
| | - Paulina Morales-Castillo
- Unidad de Genética de la Nutrición. Instituto de Investigaciones Biomédicas. Universidad Nacional Autónoma de México/ Instituto Nacional de Pediatría. Avenida del Iman#1, 4th floor, Mexico City, 04500, Mexico
| | - Cristina Fernandez-Mejia
- Unidad de Genética de la Nutrición. Instituto de Investigaciones Biomédicas. Universidad Nacional Autónoma de México/ Instituto Nacional de Pediatría. Avenida del Iman#1, 4th floor, Mexico City, 04500, Mexico.
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2
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Anhê GF, Bordin S. The adaptation of maternal energy metabolism to lactation and its underlying mechanisms. Mol Cell Endocrinol 2022; 553:111697. [PMID: 35690287 DOI: 10.1016/j.mce.2022.111697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 04/15/2022] [Accepted: 06/01/2022] [Indexed: 11/29/2022]
Abstract
Maternal energy metabolism undergoes a singular adaptation during lactation that allows for the caloric enrichment of milk. Changes in the mammary gland, changes in the white adipose tissue, brown adipose tissue, liver, skeletal muscles and endocrine pancreas are pivotal for this adaptation. The present review details the landmark studies describing the enzymatic modulation and the endocrine signals behind these metabolic changes. We will also update this perspective with data from recent studies showing transcriptional and post-transcriptional mechanisms that mediate the adaptation of the maternal metabolism to lactation. The present text will also bring experimental and observational data that describe the long-term consequences that short periods of lactation impose to maternal metabolism.
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Affiliation(s)
- Gabriel Forato Anhê
- Department of Translational Medicine, School of Medical Sciences, State University of Campinas, Campinas, Brazil.
| | - Silvana Bordin
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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Hill M, Pařízek A, Šimják P, Koucký M, Anderlová K, Krejčí H, Vejražková D, Ondřejíková L, Černý A, Kancheva R. Steroids, steroid associated substances and gestational diabetes mellitus. Physiol Res 2021. [DOI: 10.33549//physiolres.934794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
As gestational diabetes mellitus (GDM) is both a frequent and serious complication, steroid levels in pregnancy are extremely elevated and their role in pregnancy is crucial, this review focuses on the role of steroids and related substances in the GDM pathophysiology. Low SHBG levels are associated with insulin resistance and hyperinsulinemia, while also predicting a predisposition to GDM. Other relevant agents are placental hormones such as kisspeptin and CRH, playing also an important role beyond pregnancy, but which are synthesized here in smaller amounts in the hypothalamus. These hormones affect both the course of pregnancy as well as the synthesis of pregnancy steroids and may also be involved in the GDM pathophysiology. Steroids, whose biosynthesis is mainly provided by the fetal adrenal glands, placenta, maternal adrenal glands, and both maternal and fetal livers, are also synthesized in limited amounts directly in the pancreas and may influence the development of GDM. These substances involve the sulfated Δ5 steroids primarily acting via modulating different ion channels and influencing the development of GDM in different directions, mostly diabetogenic progesterone and predominantly anti-diabetic estradiol acting both in genomic and non-genomic way, androgens associated with IR and hyperinsulinemia, neuroactive steroids affecting the pituitary functioning, and cortisol whose production is stimulated by CRH but which suppresses its pro-inflammatory effects. Due to the complex actions of steroids, studies assessing their predominant effect and studies assessing their predictive values for estimating predisposition to GDM are needed.
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Affiliation(s)
- M Hill
- Institute of Endocrinology, Prague, Czech Republic.
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Teixeira CJ, Santos-Silva JC, de Souza DN, Rafacho A, Anhe GF, Bordin S. Dexamethasone during pregnancy impairs maternal pancreatic β-cell renewal during lactation. Endocr Connect 2019; 8:120-131. [PMID: 30768422 PMCID: PMC6376996 DOI: 10.1530/ec-18-0505] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 01/21/2019] [Indexed: 12/18/2022]
Abstract
Pancreatic islets from pregnant rats develop a transitory increase in the pancreatic β-cell proliferation rate and mass. Increased apoptosis during early lactation contributes to the rapid reversal of those morphological changes. Exposure to synthetic glucocorticoids during pregnancy has been previously reported to impair insulin secretion, but its impacts on pancreatic islet morphological changes during pregnancy and lactation have not been described. To address this issue, we assessed the morphological and molecular characteristics of pancreatic islets from rats that underwent undisturbed pregnancy (CTL) or were treated with dexamethasone between the 14th and 19th days of pregnancy (DEX). Pancreatic islets were analyzed on the 20th day of pregnancy (P20) and on the 3rd, 8th, 14th and 21st days of lactation (L3, L8, L14 and L21, respectively). Pancreatic islets from CTL rats exhibited transitory increases in cellular proliferation and pancreatic β-cell mass at P20, which were reversed at L3, when a transitory increase in apoptosis was observed. This was followed by the appearance of morphological features of pancreatic islet neogenesis at L8. Islets from DEX rats did not demonstrate an increase in apoptosis at L3, which coincided with an increase in the expression of M2 macrophage markers relative to M1 macrophage and T lymphocyte markers. Islets from DEX rats also did not exhibit the morphological characteristics of pancreatic islet neogenesis at L8. Our data demonstrate that maternal pancreatic islets undergo a renewal process during lactation that is impaired by exposure to DEX during pregnancy.
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Affiliation(s)
- Caio Jordão Teixeira
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, Brazil
| | | | - Dailson Nogueira de Souza
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, Brazil
| | - Alex Rafacho
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Gabriel Forato Anhe
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, Brazil
| | - Silvana Bordin
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
- Correspondence should be addressed to S Bordin:
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Abstract
Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades, but the mechanisms involved are still not clarified. In this review the information obtained in previous studies is recapitulated together with some of the current attempts to resolve the controversy in the field: identification of the putative progenitor cells, identification of the factors involved in the expansion of the beta cell mass in human pregnancy, and the relative roles of endocrine factors and nutrients.
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Affiliation(s)
- Jens Høiriis Nielsen
- CONTACT Jens Høiriis Nielsen, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, Bldg. 6.5, DK-2200 Copenhagen N, Denmark
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Hasni Ebou M, Singh-Estivalet A, Launay JM, Callebert J, Tronche F, Ferré P, Gautier JF, Guillemain G, Bréant B, Blondeau B, Riveline JP. Glucocorticoids Inhibit Basal and Hormone-Induced Serotonin Synthesis in Pancreatic Beta Cells. PLoS One 2016; 11:e0149343. [PMID: 26901633 PMCID: PMC4763453 DOI: 10.1371/journal.pone.0149343] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 01/29/2016] [Indexed: 12/31/2022] Open
Abstract
Diabetes is a major complication of chronic Glucocorticoids (GCs) treatment. GCs induce insulin resistance and also inhibit insulin secretion from pancreatic beta cells. Yet, a full understanding of this negative regulation remains to be deciphered. In the present study, we investigated whether GCs could inhibit serotonin synthesis in beta cell since this neurotransmitter has been shown to be involved in the regulation of insulin secretion. To this aim, serotonin synthesis was evaluated in vitro after treatment with GCs of either islets from CD1 mice or MIN6 cells, a beta-cell line. We also explored the effect of GCs on the stimulation of serotonin synthesis by several hormones such as prolactin and GLP 1. We finally studied this regulation in islet in two in vivo models: mice treated with GCs and with liraglutide, a GLP1 analog, and mice deleted for the glucocorticoid receptor in the pancreas. We showed in isolated islets and MIN6 cells that GCs decreased expression and activity of the two key enzymes of serotonin synthesis, Tryptophan Hydroxylase 1 (Tph1) and 2 (Tph2), leading to reduced serotonin contents. GCs also blocked the induction of serotonin synthesis by prolactin or by a previously unknown serotonin activator, the GLP-1 analog exendin-4. In vivo, activation of the Glucagon-like-Peptide-1 receptor with liraglutide during 4 weeks increased islet serotonin contents and GCs treatment prevented this increase. Finally, islets from mice deleted for the GR in the pancreas displayed an increased expression of Tph1 and Tph2 and a strong increased serotonin content per islet. In conclusion, our results demonstrate an original inhibition of serotonin synthesis by GCs, both in basal condition and after stimulation by prolactin or activators of the GLP-1 receptor. This regulation may contribute to the deleterious effects of GCs on beta cells.
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Affiliation(s)
- Moina Hasni Ebou
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Amrit Singh-Estivalet
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Jean-Marie Launay
- INSERM U942, Assistance Publique–Hôpitaux de Paris (AP-HP), Hôpital Lariboisière, Service de Biochimie, Paris, France
| | - Jacques Callebert
- INSERM U942, Assistance Publique–Hôpitaux de Paris (AP-HP), Hôpital Lariboisière, Service de Biochimie, Paris, France
| | - François Tronche
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- CNRS UMR INSERM 952-CNRS 7224, Paris, France
| | - Pascal Ferré
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Jean-François Gautier
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Department of Diabetes and Endocrinology, Hôpital Lariboisière, AP-HP, Paris, France
- Université Paris Diderot, Paris, France
| | - Ghislaine Guillemain
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Bernadette Bréant
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Bertrand Blondeau
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- * E-mail:
| | - Jean-Pierre Riveline
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Sorbonne Universités, UPMC, Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
- Department of Diabetes and Endocrinology, Hôpital Lariboisière, AP-HP, Paris, France
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Zhang C, Li L, Zhao B, Jiao A, Li X, Sun N, Zhang J. Ghrelin Protects against Dexamethasone-Induced INS-1 Cell Apoptosis via ERK and p38MAPK Signaling. Int J Endocrinol 2016; 2016:4513051. [PMID: 27190513 PMCID: PMC4844876 DOI: 10.1155/2016/4513051] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/10/2016] [Accepted: 03/23/2016] [Indexed: 11/17/2022] Open
Abstract
Glucocorticoid excess induces apoptosis of islet cells, which may result in diabetes. In this study, we investigated the protective effect of ghrelin on dexamethasone-induced INS-1 cell apoptosis. Our data showed that ghrelin (0.1 μM) inhibited dexamethasone-induced (0.1 μM) apoptosis of INS-1 cells and facilitated cell proliferation. Moreover, ghrelin upregulated Bcl-2 expression, downregulated Bax expression, and decreased caspase-3 activity. The protective effect of ghrelin against dexamethasone-induced INS-1 cell apoptosis was mediated via growth hormone secretagogue receptor 1a. Further studies revealed that ghrelin increased ERK activation and decreased p38MAPK expression after dexamethasone treatment. Ghrelin-mediated protection of dexamethasone-induced apoptosis of INS-1 cells was attenuated using the ERK inhibitor U0126 (10 μM), and cell viability increased using the p38MAPK inhibitor SB203580 (10 μM). In conclusion, ghrelin could protect against dexamethasone-induced INS-1 cell apoptosis, at least partially via GHS-R1a and the signaling pathway of ERK and p38MAPK.
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Affiliation(s)
- Chengshuo Zhang
- Hepatobiliary Surgery Department and Unit of Organ Transplantation, First Hospital of China Medical University, Shenyang 110001, China
| | - Le Li
- Hepatobiliary Surgery Department, Chifeng Municipal Hospital, Chifeng 024000, China
| | - Bochao Zhao
- Hepatobiliary Surgery Department and Unit of Organ Transplantation, First Hospital of China Medical University, Shenyang 110001, China
| | - Ao Jiao
- Hepatobiliary Surgery Department and Unit of Organ Transplantation, First Hospital of China Medical University, Shenyang 110001, China
| | - Xin Li
- Department of General Surgery, Fourth Hospital of China Medical University, Shenyang 110032, China
| | - Ning Sun
- Hepatobiliary Surgery Department and Unit of Organ Transplantation, First Hospital of China Medical University, Shenyang 110001, China
| | - Jialin Zhang
- Hepatobiliary Surgery Department and Unit of Organ Transplantation, First Hospital of China Medical University, Shenyang 110001, China
- *Jialin Zhang:
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Regulation of Glucose Homeostasis by Glucocorticoids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015. [PMID: 26215992 DOI: 10.1007/978-1-4939-2895-8_5] [Citation(s) in RCA: 357] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glucocorticoids are steroid hormones that regulate multiple aspects of glucose homeostasis. Glucocorticoids promote gluconeogenesis in liver, whereas in skeletal muscle and white adipose tissue they decrease glucose uptake and utilization by antagonizing insulin response. Therefore, excess glucocorticoid exposure causes hyperglycemia and insulin resistance. Glucocorticoids also regulate glycogen metabolism. In liver, glucocorticoids increase glycogen storage, whereas in skeletal muscle they play a permissive role for catecholamine-induced glycogenolysis and/or inhibit insulin-stimulated glycogen synthesis. Moreover, glucocorticoids modulate the function of pancreatic α and β cells to regulate the secretion of glucagon and insulin, two hormones that play a pivotal role in the regulation of blood glucose levels. Overall, the major glucocorticoid effect on glucose homeostasis is to preserve plasma glucose for brain during stress, as transiently raising blood glucose is important to promote maximal brain function. In this chapter we will discuss the current understanding of the mechanisms underlying different aspects of glucocorticoid-regulated mammalian glucose homeostasis.
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Antolic A, Feng X, Wood CE, Richards EM, Keller-Wood M. Increased maternal nighttime cortisol concentrations in late gestation alter glucose and insulin in the neonatal lamb. Physiol Rep 2015; 3:3/9/e12548. [PMID: 26371232 PMCID: PMC4600389 DOI: 10.14814/phy2.12548] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Previous studies in our laboratory have shown that a modest chronic increase in maternal cortisol concentrations impairs maternal glucose metabolism and increases the incidence of perinatal stillbirth. The dramatic outcomes prevented our ability to study the effects of maternal hypercortisolemia on neonatal growth, glucose metabolism, and hypothalamo–pituitary–adrenal axis response. Therefore, we developed a model in which pregnant ewes are infused for 12 h/day at 0.5 mg·kg–1·day–1 from day 115 of gestation until delivery (˜145), elevating nighttime plasma cortisol concentrations. This pattern of elevation of cortisol mimics that in patients with elevated evening cortisol concentrations, as in Cushing’s syndrome or chronic depression. Plasma cortisol, glucose, insulin, and electrolytes were measured during pregnancy and postpartum in control and cortisol-infused ewes and their postnatal lambs for the first 14 days after delivery. Neonatal growth and plasma ACTH, aldosterone, renin activity, and electrolytes, and organ weights at 14 days of age were also measured. Infusion of cortisol increased maternal plasma cortisol during pregnancy but not postpartum, and did not alter neonatal ACTH or cortisol. Although maternal glucose and insulin concentrations were not changed by the maternal infusion of cortisol, neonatal plasma glucose was increased and plasma insulin was decreased compared to those in the control group. Neonatal ponderal index and kidney weight were reduced, left ventricular wall thickness was increased, and plasma sodium and creatinine were increased after maternal cortisol infusion. These results suggest that excess maternal cortisol concentrations in late gestation alter growth, glucose and insulin regulation, and organ maturation in the neonate.
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Affiliation(s)
- Andrew Antolic
- Department of Pharmacodynamics, University of Florida, Gainesville, Florida
| | - Xiaodi Feng
- Department of Pharmacodynamics, University of Florida, Gainesville, Florida
| | - Charles E Wood
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Elaine M Richards
- Department of Pharmacodynamics, University of Florida, Gainesville, Florida
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SALVATIERRA CRISTIANAS, REIS SÍLVIAR, PESSOA ANAF, SOUZA LETÍCIAMDE, STOPPIGLIA LUIZF, VELOSO ROBERTOV, REIS MARISEA, CARNEIRO EVERARDOM, BOSCHERO ANTONIOC, COLODEL EDSONM, ARANTES VANESSAC, LATORRACA MÁRCIAQ. Short-term low-protein diet during pregnancy alters islet area and protein content of phosphatidylinositol 3-kinase pathway in rats. ACTA ACUST UNITED AC 2015; 87:1007-18. [DOI: 10.1590/0001-3765201520140251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 12/15/2014] [Indexed: 12/31/2022]
Abstract
The phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways mediate β cell growth, proliferation, survival and death. We investigated whether protein restriction during pregnancy alters islet morphometry or the expression and phosphorylation of several proteins involved in the phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways. As controls, adult pregnant and non-pregnant rats were fed a normal-protein diet (17%). Pregnant and non-pregnant rats in the experimental groups were fed a low-protein diet (6%) for 15 days. Low protein diet during pregnancy increased serum prolactin level, reduced serum corticosterone concentration and the expression of both protein kinase B/AKT1 (AKT1) and p70 ribosomal protein S6 kinase (p70S6K), as well as the islets area, but did not alter the insulin content of pancreatic islets. Pregnancy increased the expression of the Src homology/collagen (SHC) protein and the extracellular signal-regulated kinases 1/2 (ERK1/2) independent of diet. ERK1/2 phosphorylation (pERK1/2) was similar in islets from pregnant and non-pregnant rats fed a low-protein diet, and was higher in islets from pregnant rats than in islets from non-pregnant rats fed a normal-protein diet. Thus, a short-term, low-protein diet during pregnancy was sufficient to reduce the levels of proteins in the phosphatidylinositol 3-kinase pathway and affect islet morphometry.
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Fransson L, dos Santos C, Wolbert P, Sjöholm Å, Rafacho A, Ortsäter H. Liraglutide counteracts obesity and glucose intolerance in a mouse model of glucocorticoid-induced metabolic syndrome. Diabetol Metab Syndr 2014; 6:3. [PMID: 24423471 PMCID: PMC3905931 DOI: 10.1186/1758-5996-6-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 01/09/2014] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Glucocorticoid excess is commonly associated with diabetogenic effects, including insulin resistance and glucose intolerance. The effects of the long-term glucagon-like peptide 1 receptor agonist treatment on the metabolic syndrome-like conditions are not yet fully elucidated. Thus, we aimed to test whether long-term liraglutide treatment could be effective as a therapy to counteract the metabolic dysfunctions induced by chronic glucocorticoid exposure. METHODS Mice were given corticosterone or vehicle via their drinking water for five consecutive weeks. In addition, mice were treated with once-daily injections of either PBS or liraglutide. RESULTS Liraglutide treatment slowed progression towards obesity and ectopic fat deposition in liver that otherwise occurred in corticosterone-treated mice. The drug reduced the increment in serum insulin caused by corticosterone, but did not affect the reduction of insulin sensitivity. Furthermore, liraglutide improved glucose control in mice exposed to corticosterone as evident by a delay in the progression towards post-prandial hyperglycemia and enhanced glucose clearance during a glucose tolerance test. Glucose-stimulated C-peptide levels were higher in those mice that had received liraglutide and corticosterone compared to mice that had been treated with corticosterone alone, indicating a positive role of liraglutide for beta-cell function. Morphometric analysis revealed increased beta- and alpha-cell masses that were associated with more Ki67-positive islet cells in corticosterone-treated mice irrespective of whether they were co-treated with liraglutide or not. Liraglutide had no discernible effect on alpha-cell mass. CONCLUSION Liraglutide can be beneficial for subjects at risk of developing metabolic complications as a result of glucocorticoid excess.
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Affiliation(s)
- Liselotte Fransson
- Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Research Center Floor 3, 118 83, Stockholm, Sweden
| | - Cristiane dos Santos
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Petra Wolbert
- Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Research Center Floor 3, 118 83, Stockholm, Sweden
| | - Åke Sjöholm
- Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Research Center Floor 3, 118 83, Stockholm, Sweden
- Department of Internal Medicine, Södertälje Hospital, SE-152 86, Södertälje, Sweden
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL, USA
| | - Alex Rafacho
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Henrik Ortsäter
- Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Research Center Floor 3, 118 83, Stockholm, Sweden
- Research Unit, Södertälje Hospital, SE-152 86, Södertälje, Sweden
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Hernandez AM, Colvin ES, Chen YC, Geiss SL, Eller LE, Fueger PT. Upregulation of p21 activates the intrinsic apoptotic pathway in β-cells. Am J Physiol Endocrinol Metab 2013; 304:E1281-90. [PMID: 23592481 PMCID: PMC3680698 DOI: 10.1152/ajpendo.00663.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Diabetes manifests from a loss in functional β-cell mass, which is regulated by a dynamic balance of various cellular processes, including β-cell growth, proliferation, and death as well as secretory function. The cell cycle machinery comprised of cyclins, kinases, and inhibitors regulates proliferation. However, their involvement during β-cell stress during the development of diabetes is not well understood. Interestingly, in a screen of multiple cell cycle inhibitors, p21 was dramatically upregulated in INS-1-derived 832/13 cells and rodent islets by two pharmacological inducers of β-cell stress, dexamethasone and thapsigargin. We hypothesized that β-cell stress upregulates p21 to activate the apoptotic pathway and suppress cell survival signaling. To this end, p21 was adenovirally overexpressed in pancreatic rat islets and 832/13 cells. As expected, p21 overexpression resulted in decreased [(3)H]thymidine incorporation. Flow cytometry analysis in p21-transduced 832/13 cells verified lower replication, as indicated by a decreased cell population in the S phase and a block in G2/M transition. The sub-G0 cell population was higher with p21 overexpression and was attributable to apoptosis, as demonstrated by increased annexin-positive stained cells and cleaved caspase-3 protein. p21-mediated caspase-3 cleavage was inhibited by either overexpression of the antiapoptotic mitochondrial protein Bcl-2 or siRNA-mediated suppression of the proapoptotic proteins Bax and Bak. Therefore, an intact intrinsic apoptotic pathway is central for p21-mediated cell death. In summary, our findings indicate that β-cell apoptosis can be triggered by p21 during stress and is thus a potential target to inhibit for protection of functional β-cell mass.
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Colvin ES, Ma HY, Chen YC, Hernandez AM, Fueger PT. Glucocorticoid-induced suppression of β-cell proliferation is mediated by Mig6. Endocrinology 2013; 154:1039-46. [PMID: 23384834 PMCID: PMC3578994 DOI: 10.1210/en.2012-1923] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glucocorticoids can cause steroid-induced diabetes or accelerate the progression to diabetes by creating systemic insulin resistance and decreasing functional β-cell mass, which is influenced by changes in β-cell function, growth, and death. The synthetic glucocorticoid agonist dexamethasone (Dex) is deleterious to functional β-cell mass by decreasing β-cell function, survival, and proliferation. However, the mechanism by which Dex decreases β-cell proliferation is unknown. Interestingly, Dex induces the transcription of an antiproliferative factor and negative regulator of epidermal growth factor receptor signaling, Mig6 (also known as gene 33, RALT, and Errfi1). We, therefore, hypothesized that Dex impairs β-cell proliferation by increasing the expression of Mig6 and thereby decreasing downstream signaling of epidermal growth factor receptor. We found that Dex induced Mig6 and decreased [(3)H]thymidine incorporation, an index of cellular replication, in mouse, rat, and human islets. Using adenovirally delivered small interfering RNA targeted to Mig6 in rat islets, we were able to limit the induction of Mig6 upon exposure to Dex, compared with islets treated with a control virus, and completely rescued the Dex-mediated impairment in replication. We demonstrated that both Dex and overexpression of Mig6 attenuated the phosphorylation of ERK1/2 and blocked the G(1)/S transition of the cell cycle. In conclusion, Mig6 functions as a molecular brake for β-cell proliferation during glucocorticoid treatment in β-cells, and thus, Mig6 may be a novel target for preventing glucocorticoid-induced impairments in functional β-cell mass.
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Affiliation(s)
- E Scott Colvin
- Department of Pediatrics and Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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14
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Kimura Y, Okitsu T, Xibao L, Teramae H, Okonogi A, Toyoda K, Uemoto S, Fukushima M. Improved hypothermic short-term storage of isolated mouse islets by adding serum to preservation solutions. Islets 2013; 5:45-52. [PMID: 23552019 PMCID: PMC3655792 DOI: 10.4161/isl.24025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Preserving isolated islets at low temperature appears attractive because it can keep islet quantity comparable to freshly isolated islets. In this study, we evaluated the effect of serum as an additive to preservation solutions on islet quality after short-term hypothermic storage. Isolated mouse islets were preserved at 4°C in University of Wisconsin solution (UW) alone, UW with serum, M-Kyoto solution (MK) alone or MK with serum. We then assessed islet quantity, morphology, viability and function in vitro as well as in vivo. Islet quantity after storage in all four solutions was well maintained for up to 120 h. However, islets functioned for different duration; glucose-stimulated insulin release assay revealed that the duration was 72 h when islets were stored in UW with serum and MK with serum, but only 24 h in UW alone, and the islet function disappeared immediately in MK alone. Viability assay confirmed that more than 70% islet cells survived for up to 48 h when islets are preserved in UW with serum and MK with serum, but the viability decreased rapidly in UW alone and MK alone. In in vivo bioassays using 48-h preserved isogeneic islets, all recipient mice restored normal blood glucose concentrations by transplants preserved in UW with serum or MK with serum, whereas 33.3% recipients and no recipient restored diabetes by transplants preserved in UW alone and in MK alone respectively. Adding serum to both UW and MK improves their capability to store isolated islets by maintaining islet functional viability.
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Affiliation(s)
- Yasuko Kimura
- Translational Research Informatics Center; Foundation for Biomedical Research and Innovation; Kobe, Japan
| | - Teru Okitsu
- Institute of Industrial Science; University of Tokyo; Tokyo, Japan
- Correspondence to: Teru Okitsu,
| | - Liu Xibao
- Department of Endocrinology; the First Hospital of Hebei Medical University; ShiJiaZhuang, China
| | - Hiroki Teramae
- Faculty of Teacher Education; Shumei University ; Yachiyo, Chiba, Japan
| | | | - Kentaro Toyoda
- Department of Diabetes and Clinical Nutrition; Graduate School of Medicine; Kyoto University; Kyoto, Japan
| | - Shinji Uemoto
- Department of Surgery; Division of Hepato-Pancreato-Biliary Surgery and Transplantation; Kyoto University Hospital; Kyoto, Japan
| | - Masanori Fukushima
- Translational Research Informatics Center; Foundation for Biomedical Research and Innovation; Kobe, Japan
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15
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Lellis-Santos C, Sakamoto LH, Bromati CR, Nogueira TCA, Leite AR, Yamanaka TS, Kinote A, Anhê GF, Bordin S. The regulation of Rasd1 expression by glucocorticoids and prolactin controls peripartum maternal insulin secretion. Endocrinology 2012; 153:3668-78. [PMID: 22700767 DOI: 10.1210/en.2012-1135] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The transition from gestation to lactation is characterized by a robust adaptation of maternal pancreatic β-cells. Consistent with the loss of β-cell mass, glucose-induced insulin secretion is down-regulated in the islets of early lactating dams. Extensive experimental evidence has demonstrated that the surge of prolactin is responsible for the morphofunctional remodeling of the maternal endocrine pancreas during pregnancy, but the precise molecular mechanisms by which this phenotype is rapidly reversed after delivery are not completely understood. This study investigated whether glucocorticoid-regulated expression of Rasd1/Dexras, a small inhibitory G protein, is involved in this physiological plasticity. Immunofluorescent staining demonstrated that Rasd1 is localized within pancreatic β-cells. Rasd1 expression in insulin-secreting cells was increased by dexamethasone and decreased by prolactin. In vivo data confirmed that Rasd1 expression is decreased in islets from pregnant rats and increased in islets from lactating mothers. Knockdown of Rasd1 abolished the inhibitory effects of dexamethasone on insulin secretion and the protein kinase A, protein kinase C, and ERK1/2 pathways. Chromatin immunoprecipitation experiments revealed that glucocorticoid receptor (GR) and signal transducer and activator of transcription 5b (STAT5b) cooperatively mediate glucocorticoid-induced Rasd1 expression in islets. Prolactin inhibited the stimulatory effect of GR/STAT5b complex on Rasd1 transcription. Overall, our data indicate that the stimulation of Rasd1 expression by glucocorticoid at the end of pregnancy reverses the increased insulin secretion that occurs during pregnancy. Prolactin negatively regulates this pathway by inhibiting GR/STAT5b transcriptional activity on the Rasd1 gene.
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Affiliation(s)
- Camilo Lellis-Santos
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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16
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Beenken-Rothkopf LN, Karfeld-Sulzer LS, Zhang X, Kissler H, Michie SA, Kaufman DB, Fontaine MJ, Barron AE. Protein polymer hydrogels: effects of endotoxin on biocompatibility. J Biomater Appl 2012; 28:395-406. [PMID: 22832218 DOI: 10.1177/0885328212454555] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Protein polymer-based hydrogels have shown potential for tissue engineering applications, but require biocompatibility testing for in vivo use. Enzymatically crosslinked protein polymer-based hydrogels were tested in vitro and in vivo to evaluate their biocompatibility. Endotoxins present in the hydrogel were removed by Trition X-114 phase separation. The reduction of endotoxins decreased TNF-α production by a macrophage cell line in vitro; however, significant inflammatory response was still present compared to collagen control gels. A branched PEG molecule and dexamethasone were added to the hydrogel to reduce the response. In vitro testing showed a decrease in the TNF-α levels with the addition of dexamethasone. In vivo implantations into the epididymal fat pad of C57/BL6 mice, however, indicated a decreased inflammatory mediated immune response with a hydrogel treated with both PEGylation and endotoxin reduction. This study demonstrates the importance of endotoxin testing and removal in determining the biocompatibility of biomaterials.
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17
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Kondegowda NG, Mozar A, Chin C, Otero A, Garcia-Ocaña A, Vasavada RC. Lactogens protect rodent and human beta cells against glucolipotoxicity-induced cell death through Janus kinase-2 (JAK2)/signal transducer and activator of transcription-5 (STAT5) signalling. Diabetologia 2012; 55:1721-32. [PMID: 22382519 DOI: 10.1007/s00125-012-2501-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 01/11/2012] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS A leading cause of type 2 diabetes is a reduction in functional beta cell mass partly due to increased beta cell death, triggered by stressors such as glucolipotoxicity (GLT). This study evaluates the hypothesis that lactogens can protect beta cells against GLT and examines the mechanism behind the pro-survival effect. METHODS The effect of exogenous treatment or endogenous expression of lactogens on GLT-induced beta cell death was examined in INS-1 cells, and in rodent and human islets. The mechanism behind the pro-survival effect of lactogens was determined using an inhibitor, siRNAs, a dominant negative (DN) mutant, and Cre-lox-mediated gene deletion analysis. RESULTS Lactogens significantly protect INS-1 and primary rodent beta cells against GLT-induced cell death. The pro-survival effect of lactogens in rodent beta cells is mediated through activation of the Janus kinase-2 (JAK2)/signal transducer and activator of transcription-5 (STAT5) signalling pathway. Lactogen-induced increase in the anti-apoptotic B cell lymphoma-extra large (BCLXL) protein is required to mediate its pro-survival effects in both INS-1 cells and primary rodent beta cells. Most importantly, lactogens significantly protect human beta cells against GLT-induced cell death, and their pro-survival effect is also mediated through the JAK2/STAT5 pathway. CONCLUSIONS/INTERPRETATION These studies, together with previous work, clearly demonstrate the pro-survival nature of lactogens and identify the JAK2/STAT5 pathway as an important mediator of this effect in both rodent and human beta cells. Future studies will determine the effectiveness of this peptide in vivo in the pathophysiology of type 2 diabetes.
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Affiliation(s)
- N Guthalu Kondegowda
- Division of Endocrinology, University of Pittsburgh, 200 Lothrop St, BST-E1157, Pittsburgh, PA 15261, USA
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18
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Demirci C, Ernst S, Alvarez-Perez JC, Rosa T, Valle S, Shridhar V, Casinelli GP, Alonso LC, Vasavada RC, García-Ocana A. Loss of HGF/c-Met signaling in pancreatic β-cells leads to incomplete maternal β-cell adaptation and gestational diabetes mellitus. Diabetes 2012; 61:1143-52. [PMID: 22427375 PMCID: PMC3331762 DOI: 10.2337/db11-1154] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hepatocyte growth factor (HGF) is a mitogen and insulinotropic agent for the β-cell. However, whether HGF/c-Met has a role in maternal β-cell adaptation during pregnancy is unknown. To address this issue, we characterized glucose and β-cell homeostasis in pregnant mice lacking c-Met in the pancreas (PancMet KO mice). Circulating HGF and islet c-Met and HGF expression were increased in pregnant mice. Importantly, PancMet KO mice displayed decreased β-cell replication and increased β-cell apoptosis at gestational day (GD)15. The decreased β-cell replication was associated with reductions in islet prolactin receptor levels, STAT5 nuclear localization and forkhead box M1 mRNA, and upregulation of p27. Furthermore, PancMet KO mouse β-cells were more sensitive to dexamethasone-induced cytotoxicity, whereas HGF protected human β-cells against dexamethasone in vitro. These detrimental alterations in β-cell proliferation and death led to incomplete maternal β-cell mass expansion in PancMet KO mice at GD19 and early postpartum periods. The decreased β-cell mass was accompanied by increased blood glucose, decreased plasma insulin, and impaired glucose tolerance. PancMet KO mouse islets failed to upregulate GLUT2 and pancreatic duodenal homeobox-1 mRNA, insulin content, and glucose-stimulated insulin secretion during gestation. These studies indicate that HGF/c-Met signaling is essential for maternal β-cell adaptation during pregnancy and that its absence/attenuation leads to gestational diabetes mellitus.
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Affiliation(s)
- Cem Demirci
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sara Ernst
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Juan C. Alvarez-Perez
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Taylor Rosa
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Shelley Valle
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Varsha Shridhar
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Gabriella P. Casinelli
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Laura C. Alonso
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rupangi C. Vasavada
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Adolfo García-Ocana
- Division of Endocrinology and Metabolism Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Corresponding author: Adolfo Garcia-Ocaña,
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19
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Dumortier O, Theys N, Ahn MT, Remacle C, Reusens B. Impairment of rat fetal beta-cell development by maternal exposure to dexamethasone during different time-windows. PLoS One 2011; 6:e25576. [PMID: 21991320 PMCID: PMC3184993 DOI: 10.1371/journal.pone.0025576] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 09/07/2011] [Indexed: 12/22/2022] Open
Abstract
Aim Glucocorticoids (GCs) take part in the direct control of cell lineage during the late phase of pancreas development when endocrine and exocrine cell differentiation occurs. However, other tissues such as the vasculature exert a critical role before that phase. This study aims to investigate the consequences of overexposure to exogenous glucocorticoids during different time-windows of gestation for the development of the fetal endocrine pancreas. Methods Pregnant Wistar rats received dexamethasone acetate in their drinking water (1 µg/ml) during the last week or throughout gestation. Fetuses and their pancreases were analyzed at day 15 and 21 of gestation. Morphometrical analysis was performed on pancreatic sections after immunohistochemistry techniques and insulin secretion was evaluated on fetal islets collected in vitro. Results Dexamethasone given the last week or throughout gestation reduced the beta-cell mass in 21-day-old fetuses by respectively 18% or 62%. This was accompanied by a defect in insulin secretion. The alpha-cell mass was reduced similarly. Neither islet vascularization nor beta-cell proliferation was affected when dexamethasone was administered during the last week, which was however the case when given throughout gestation. When given from the beginning of gestation, dexamethasone reduced the number of cells expressing the early marker of endocrine lineage neurogenin-3 when analyzed at 15 days of fetal age. Conclusions GCs reduce the beta- and alpha-cell mass by different mechanisms according to the stage of development during which the treatment was applied. In fetuses exposed to glucocorticoids the last week of gestation only, beta-cell mass is reduced due to impairment of beta-cell commitment, whereas in fetuses exposed throughout gestation, islet vascularization and lower beta-cell proliferation are involved as well, amplifying the reduction of the endocrine mass.
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Affiliation(s)
- Olivier Dumortier
- Laboratoire de Biologie Cellulaire, Université catholique de Louvain, Institut des Sciences de la Vie, Louvain-la-Neuve, Belgium
| | - Nicolas Theys
- Laboratoire de Biologie Cellulaire, Université catholique de Louvain, Institut des Sciences de la Vie, Louvain-la-Neuve, Belgium
| | - Marie-Thérèse Ahn
- Laboratoire de Biologie Cellulaire, Université catholique de Louvain, Institut des Sciences de la Vie, Louvain-la-Neuve, Belgium
| | - Claude Remacle
- Laboratoire de Biologie Cellulaire, Université catholique de Louvain, Institut des Sciences de la Vie, Louvain-la-Neuve, Belgium
| | - Brigitte Reusens
- Laboratoire de Biologie Cellulaire, Université catholique de Louvain, Institut des Sciences de la Vie, Louvain-la-Neuve, Belgium
- * E-mail:
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20
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Baxi DB, Singh PK, Vachhrajani KD, Ramachandran AV. Plasticity changes in adult metabolic homeostasis and tissue oxidative stress: neonatal programming by corticosterone and melatonin as deprogrammer. J Matern Fetal Neonatal Med 2011; 25:831-44. [PMID: 21848498 DOI: 10.3109/14767058.2011.599456] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To evaluate the long-term plasticity changes induced by neonatal corticosterone programming on adult metabolic status and the deprogramming effect of melatonin. METHODS Male and female Wistar rats were maintained under standard conditions and when mated females delivered pups, neonates of both sexes were separated and equal number of pups was assigned to lactating mothers. Pups treated with saline, corticosterone or a combination of corticosterone and melatonin from PND 2 to PND 14, were maintained until 120 days of age. Various serum and tissue parameters pertaining to glycaemic regulation, dyslipidemia, hepatic and renal distress and oxidative stress were analyzed in adult rats. RESULTS Neonatal corticosterone exposure induced dyslipidemia, increased fed and fasting glucose levels, insulin resistance, lipid peroxidation, serum levels of insulin, corticosterone and hepatic and renal dysfunction markers and decreased the levels of enzymatic and non-enzymatic antioxidants, relatively more in males. Melatonin proved as an effective deprogrammer of corticosterone induced plasticity changes. CONCLUSIONS Neonatal corticosterone exposure induces long lasting effects on adult physiology and metabolism. Concurrent treatment with melatonin effectively deprograms the changes.
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Affiliation(s)
- Darshee B Baxi
- Division of Metabolic Endocrinology, Department of Zoology, Faculty of Science, The M.S.University of Baroda, Vadodara, Gujarat, India
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21
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Nicoletti-Carvalho JE, Lellis-Santos C, Yamanaka TS, Nogueira TC, Caperuto LC, Leite AR, Anhê GF, Bordin S. MKP-1 mediates glucocorticoid-induced ERK1/2 dephosphorylation and reduction in pancreatic ß-cell proliferation in islets from early lactating mothers. Am J Physiol Endocrinol Metab 2010; 299:E1006-15. [PMID: 20858750 DOI: 10.1152/ajpendo.00341.2010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maternal pancreatic islets undergo a robust increase of mass and proliferation during pregnancy, which allows a compensation of gestational insulin resistance. Studies have described that this adaptation switches to a low proliferative status after the delivery. The mechanisms underlying this reversal are unknown, but the action of glucocorticoids (GCs) is believed to play an important role because GCs counteract the pregnancy-like effects of PRL on isolated pancreatic islets maintained in cell culture. Here, we demonstrate that ERK1/2 phosphorylation (phospho-ERK1/2) is increased in maternal rat islets isolated on the 19th day of pregnancy. Phospho-ERK1/2 status on the 3rd day after delivery (L3) rapidly turns to values lower than that found in virgin control rats (CTL). MKP-1, a protein phosphatase able to dephosphorylate ERK1/2, is increased in islets from L3 rats. Chromatin immunoprecipitation assay revealed that binding of glucocorticoid receptor (GR) to MKP-1 promoter is also increased in islets from L3 rats. In addition, dexamethasone (DEX) reduced phospho-ERK1/2 and increased MKP-1 expression in RINm5F and MIN-6 cells. Inhibition of transduction with cycloheximide and inhibition of phosphatases with orthovanadate efficiently blocked DEX-induced downregulation of phospho-ERK1/2. In addition, specific knockdown of MKP-1 with siRNA suppressed the downregulation of phospho-ERK1/2 and the reduction of proliferation induced by DEX. Altogether, our results indicate that downregulation of phospho-ERK1/2 is associated with reduction in proliferation found in islets of early lactating mothers. This mechanism is probably mediated by GC-induced MKP-1 expression.
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22
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Finlay C, Argoud K, Wilder SP, Ouali F, Ktorza A, Kaisaki PJ, Gauguier D. Chromosomal mapping of pancreatic islet morphological features and regulatory hormones in the spontaneously diabetic (Type 2) Goto-Kakizaki rat. Mamm Genome 2010; 21:499-508. [PMID: 20878524 PMCID: PMC2974204 DOI: 10.1007/s00335-010-9285-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2010] [Accepted: 09/01/2010] [Indexed: 12/02/2022]
Abstract
Insulin resistance and altered endocrine pancreas function are central pathophysiological features of type 2 diabetes mellitus (T2DM). The Goto-Kakizaki (GK) rat is a model of spontaneous T2DM characterised by reduced beta cell mass and genetically determined glucose intolerance and altered insulin secretion. To identify genetic determinants of endocrine pancreas histopathology, we carried out quantitative trait locus (QTL) mapping of histological phenotypes (beta cell mass -BCM and insulin-positive cell area -IPCA) and plasma concentration of hormones and growth factors in a F2 cohort derived from GK and normoglycemic Brown Norway rats. Although IPCA and BCM in the duodenal region of the pancreas were highly positively correlated (P < 10−6), and similarly in the splenic region, both measures were poorly correlated when comparing duodenal and splenic phenotypes. Strongest evidence of linkage to pancreas morphological traits was obtained between BCM and chromosome 10 (LOD 3.2). Evidence of significant linkage (LOD 4.2) to plasma corticosterone was detected in a region of chromosome 1 distal to other QTLs previously identified in the GK. Male-specific genetic effects were detected, including linkages (LOD > 4) to growth hormome (GH) on chromosome 6 and prolactin on chromosome 17. These data suggest independent genetic control of the structure and function of ontologically different regions of the endocrine pancreas. Novel QTLs for corticosterone, prolactin and GH may contribute to diabetes in the GK. The QTLs that we have identified in this, and previous genetic studies collectively underline the complex and multiple mechanisms involved in diabetes in the GK strain.
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Affiliation(s)
- Clare Finlay
- The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Headington, Oxford, OX3 7BN, UK
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23
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Arumugam R, Horowitz E, Noland RC, Lu D, Fleenor D, Freemark M. Regulation of islet beta-cell pyruvate metabolism: interactions of prolactin, glucose, and dexamethasone. Endocrinology 2010; 151:3074-83. [PMID: 20484462 PMCID: PMC2903933 DOI: 10.1210/en.2010-0049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Prolactin (PRL) induces beta-cell proliferation and glucose-stimulated insulin secretion (GSIS) and counteracts the effects of glucocorticoids on insulin production. The mechanisms by which PRL up-regulates GSIS are unknown. We used rat islets and insulinoma (INS-1) cells to explore the interactions of PRL, glucose, and dexamethasone (DEX) in the regulation of beta-cell pyruvate carboxylase (PC), pyruvate dehydrogenase (PDH), and the pyruvate dehydrogenase kinases (PDKs), which catalyze the phosphorylation and inactivation of PDH. PRL increased GSIS by 37% (P < 0.001) in rat islets. Glucose at supraphysiological concentrations (11 mm) increased PC mRNA in islets; in contrast, PRL suppressed PC mRNA levels in islets and INS-1 cells, whereas DEX was without effect. Neither PRL nor DEX altered PC protein or activity levels. In INS-1 cells, PRL increased PDH activity 1.4- to 2-fold (P < 0.05-0.001) at glucose concentrations ranging from 2.5-11 mm. DEX reduced PDH activity; this effect was reversed by PRL. PDK1, -2, -3, and -4 mRNAs were detected in both islets and insulinoma cells, but the latter expressed trivial amounts of PDK4. PRL reduced PDK2 mRNA and protein levels in rat islets and INS-1 cells and PDK4 mRNA in islets; DEX increased PDK2 mRNA in islets and INS-1 cells; this effect was reversed by PRL. Our findings suggest that PRL induction of GSIS is mediated by increases in beta-cell PDH activity; this is facilitated by suppression of PDKs. PRL counteracts the effects of DEX on PDH and PDK expression, suggesting novel roles for the lactogens in the defense against diabetes.
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Affiliation(s)
- Ramamani Arumugam
- Pediatric Endocrinology, Duke University Medical Center, Box 102820, Duke University Medical Center, Durham, NC 27710, USA.
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24
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Rashidi A, Kirkwood TBL, Shanley DP. Metabolic evolution suggests an explanation for the weakness of antioxidant defences in beta-cells. Mech Ageing Dev 2009; 130:216-21. [PMID: 19396979 DOI: 10.1016/j.mad.2008.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The lack of an effective antioxidant system in beta-cells, which renders them susceptible to oxidative stress, is to date without explanation. The particular weakness of beta-cells in females, in both humans and mice, is another unexplained observation. We hypothesise that reactive oxygen species (ROS) in beta-cells, by their negative effect on insulin synthesis/secretion, play a fitness-enhancing role for the whole organism. Under stress conditions, the release of stress hormones produces insulin resistance and, owing to ROS preventing beta-cells from secreting insulin at the level required to maintain homeostasis, diverts glucose to insulin-independent tissues such as the brain and the foetus. We suggest that pancreatic beta-cells lost part of their antioxidant defence in association with brain evolution, and lost even more in females when placental mammals evolved. The unusual antioxidant status of beta-cells may thus be explained as an instance of co-evolution of the brain, cortisol and corticosteroid receptors, and beta-cells in the endocrine pancreas.
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Affiliation(s)
- Armin Rashidi
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK.
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25
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Johansson M, Olerud J, Jansson L, Carlsson PO. Prolactin treatment improves engraftment and function of transplanted pancreatic islets. Endocrinology 2009; 150:1646-53. [PMID: 19095742 DOI: 10.1210/en.2008-1318] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Transplantation of pancreatic islets is clinically used to treat type 1 diabetes but requires multiple donors. Previous experimental studies demonstrated that transplanted islets have a low blood vessel density, which leads to a hypoxic microenvironment. The present study tested the hypothesis that experimental prolactin pretreatment, a substance that seems to stimulate angiogenesis in endogenous islets, would increase graft blood vessel density, thereby improving transplantation outcome. Pancreatic islets from C57BL/6 mice were incubated with prolactin (500 ng/ml) or vehicle during the last 24 h of culture before syngeneic transplantation beneath the renal capsule, or recipients were injected with prolactin or vehicle for the first 7 d after transplantation. One month after transplantation, graft vascular density, blood flow, oxygen tension, endocrine volume, and function were evaluated. Also, human islets were incubated with prolactin or vehicle before experimental transplantation and investigated for vascular engraftment. Vascular engraftment of syngeneically transplanted mouse islets was improved by both in vivo and in vitro prolactin pretreatment. Moreover, prolactin pretreatment in vitro of islets used for transplantation improved recovery from diabetes in a minimal islet mass model. Interestingly, also human islets subjected to prolactin treatment before experimental transplantation demonstrated improved revascularization, blood perfusion, and oxygen tension when evaluated 1 month after transplantation. We conclude that prolactin may improve engraftment of transplanted pancreatic islets. The protocol with pretreatment of islets ex vivo could minimize the risk of side effects when used in the clinical setting.
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Affiliation(s)
- Magnus Johansson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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26
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Arumugam R, Horowitz E, Lu D, Collier JJ, Ronnebaum S, Fleenor D, Freemark M. The interplay of prolactin and the glucocorticoids in the regulation of beta-cell gene expression, fatty acid oxidation, and glucose-stimulated insulin secretion: implications for carbohydrate metabolism in pregnancy. Endocrinology 2008; 149:5401-14. [PMID: 18599550 PMCID: PMC2584602 DOI: 10.1210/en.2008-0051] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Carbohydrate metabolism in pregnancy reflects the balance between counterregulatory hormones, which induce insulin resistance, and lactogenic hormones, which stimulate beta-cell proliferation and insulin production. Here we explored the interactions of prolactin (PRL) and glucocorticoids in the regulation of beta-cell gene expression, fatty acid oxidation, and glucose-stimulated insulin secretion (GSIS). In rat insulinoma cells, rat PRL caused 30-50% (P < 0.001) reductions in Forkhead box O (FoxO)-1, peroxisome proliferator activator receptor (PPAR)-gamma coactivator-1alpha (PGC-1alpha), PPARalpha, and carnitine palmitoyltransferase 1 (CPT-1) mRNAs and increased Glut-2 mRNA and GSIS; conversely, dexamethasone (DEX) up-regulated FoxO1, PGC1alpha, PPARalpha, CPT-1, and uncoupling protein 2 (UCP-2) mRNAs in insulinoma cells and inhibited GSIS. Hydrocortisone had similar effects. The effects of DEX were attenuated by coincubation of cells with PRL. In primary rat islets, PRL reduced FoxO1, PPARalpha, and CPT-1 mRNAs, whereas DEX increased FoxO1, PGC1alpha, and UCP-2 mRNAs. The effects of PRL on gene expression were mimicked by constitutive overexpression of signal transducer and activator of transcription-5b. PRL induced signal transducer and activator of transcription-5 binding to a consensus sequence in the rat FoxO1 promoter, reduced nuclear FoxO1 protein levels, and induced its phosphorylation and cytoplasmic redistribution. DEX increased beta-cell fatty acid oxidation and reduced fatty acid esterification; these effects were attenuated by PRL. Thus, lactogens and glucocorticoids have opposing effects on a number of beta-cell genes including FoxO1, PGC1alpha, PPARalpha, CPT-1, and UCP-2 and differentially regulate beta-cell Glut-2 expression, fatty acid oxidation, and GSIS. These observations suggest new mechanisms by which lactogens may preserve beta-cell mass and function and maternal glucose tolerance despite the doubling of maternal cortisol concentrations in late gestation.
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Affiliation(s)
- Ramamani Arumugam
- Departments of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710, USA
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Avram D, Ranta F, Hennige AM, Berchtold S, Hopp S, Häring HU, Lang F, Ullrich S. IGF-1 protects against dexamethasone-induced cell death in insulin secreting INS-1 cells independent of AKT/PKB phosphorylation. Cell Physiol Biochem 2008; 21:455-62. [PMID: 18453753 DOI: 10.1159/000129638] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2007] [Indexed: 12/16/2022] Open
Abstract
Appropriate insulin secretion depends on beta-cell mass that is determined by the balance between cell proliferation and death. IGF-1 stimulates proliferation and protects against apoptosis. In contrast, glucocorticoids promote cell death. In this study we examined molecular interactions of the glucocorticoid dexamethasone (dexa) with IGF-1 signalling pathways in insulin secreting INS-1 cells. IGF-1 (50 ng/ml) increased the growth rate and stimulated BrdU incorporation, while dexa (100 nmol/l) inhibited cell growth, BrdU incorporation and induced apoptosis. Dexa-induced cell death was partially antagonized by IGF-1. This protection was further increased by LY294002 (10 micromol/l), an inhibitor of PI3 kinase. In contrast, MAP kinase inhibitor PD98059 (10 micromol/l) significantly reduced the protective effect of IGF-1. The analysis of signalling pathways by Western blotting revealed that dexa increased IRS-2 protein abundance while the expression of PI3K, PKB and ERK remained unchanged. Despite increased IRS-2 protein,IRS-2 tyrosine phosphorylation stimulated by IGF-1 was inhibited by dexa. Dexa treatment reduced basal PKB phosphorylation. However, IGF-1-mediated stimulation of PKB phosphorylation was not affected by dexa, but ERK phosphorylation was reduced. LY294002 restored IGF-1-induced ERK phosphorylation. These data suggest that dexa induces apoptosis in INS-1 cells by inhibiting phosphorylation of IRS-2, PKB and ERK. IGF-1 counteracts dexa-mediated apoptosis in the presence of reduced PKB but increased ERK phosphorylation.
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Affiliation(s)
- Diana Avram
- Institute of Physiology, University of Tübingen, Germany
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Karnik SK, Chen H, McLean GW, Heit JJ, Gu X, Zhang AY, Fontaine M, Yen MH, Kim SK. Menin controls growth of pancreatic beta-cells in pregnant mice and promotes gestational diabetes mellitus. Science 2007; 318:806-9. [PMID: 17975067 DOI: 10.1126/science.1146812] [Citation(s) in RCA: 251] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
During pregnancy, maternal pancreatic islets grow to match dynamic physiological demands, but the mechanisms regulating adaptive islet growth in this setting are poorly understood. Here we show that menin, a protein previously characterized as an endocrine tumor suppressor and transcriptional regulator, controls islet growth in pregnant mice. Pregnancy stimulated proliferation of maternal pancreatic islet beta-cells that was accompanied by reduced islet levels of menin and its targets. Transgenic expression of menin in maternal beta-cells prevented islet expansion and led to hyperglycemia and impaired glucose tolerance, hallmark features of gestational diabetes. Prolactin, a hormonal regulator of pregnancy, repressed islet menin levels and stimulated beta-cell proliferation. These results expand our understanding of mechanisms underlying diabetes pathogenesis and reveal potential targets for therapy in diabetes.
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Affiliation(s)
- Satyajit K Karnik
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
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Holness MJ, Greenwood GK, Smith ND, Sugden MC. Peroxisome proliferator-activated receptor-alpha and glucocorticoids interactively regulate insulin secretion during pregnancy. Diabetes 2006; 55:3501-8. [PMID: 17130498 DOI: 10.2337/db06-0666] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We evaluated the impact of peroxisome proliferator-activated receptor (PPAR)alpha activation and dexamethasone treatment on islet adaptations to the distinct metabolic challenges of fasting and pregnancy, situations where lipid handling is modified to conserve glucose. PPARalpha activation (24 h) in vivo did not affect glucose-stimulated insulin secretion (GSIS) in nonpregnant female rats in the fasted state, although fasting suppressed GSIS. Dexamethasone treatment (5 days) of nonpregnant rats lowered the glucose threshold and augmented GSIS at high glucose; the former effect was selectively opposed by PPARalpha activation. Pregnancy-induced changes in GSIS were opposed by PPARalpha activation at day 19 of pregnancy. Dexamethasone treatment from day 14 to 19 of pregnancy did not modify the GSIS profile of perifused islets from 19-day pregnant rats but rendered the islet GSIS profile refractory to PPARalpha activation. During sustained hyperglycemia in vivo, dexamethasone treatment augmented GSIS in nonpregnant rats but limited further modification of GSIS by pregnancy. We propose that the effect of PPARalpha activation to oppose lowering of the glucose threshold for GSIS by glucocorticoids is important as part of the fasting adaptation, and modulation of the islet GSIS profile by glucocorticoids toward term facilitates the transition of maternal islet function from the metabolic demands of pregnancy to those imposed after parturition.
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Affiliation(s)
- Mark J Holness
- Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, 4 Newark St., Whitechapel, London E1 2AT, U.K
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Liu HK, Green BD, McClenaghan NH, McCluskey JT, Flatt PR. Deleterious Effects of Supplementation with Dehydroepiandrosterone Sulphate or Dexamethasone on Rat Insulin-Secreting Cells Under In Vitro Culture Condition. Biosci Rep 2006; 26:31-8. [PMID: 16779665 DOI: 10.1007/s10540-006-9001-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Dehydroepiandrosterone (DHEA) and glucocorticoids are steroid hormones synthesised in the adrenal cortex. Administration of DHEA, its sulphate derivative, DHEAS, and more controversially dexamethasone (DEX), a synthetic glucocorticoid, have beneficial effects in diabetic animals. Cultivating BRIN-BD11 cells for 3 days with either DHEAS (30 μM) or DEX (100 nM), reduced total cell number and reduced cell viability and cellular insulin content. DHEAS-treated cells had poor glucose responsiveness and regulated insulin release, coupled with reduced basal insulin release. In contrast, DEX-treated cells lacked responsiveness to glucose and membrane depolarisation, and both protein kinase A (PKA) and protein kinase C (PKC) secretory pathways were desensitised. Therefore, we conclude that this steroid hormone and synthetic glucocorticoid are not beneficial to pancreatic β-cells in vitro.
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Affiliation(s)
- Hui-Kang Liu
- School of Biomedical Sciences, University of Ulster, BT52 1SA, Coleraine, N. Ireland, UK
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Ranta F, Avram D, Berchtold S, Düfer M, Drews G, Lang F, Ullrich S. Dexamethasone induces cell death in insulin-secreting cells, an effect reversed by exendin-4. Diabetes 2006; 55:1380-90. [PMID: 16644695 DOI: 10.2337/db05-1220] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Glucocorticoid excess induces hyperglycemia, which may result in diabetes. The present experiments explored whether glucocorticoids trigger apoptosis in insulin-secreting cells. Treatment of mouse beta-cells or INS-1 cells with the glucocorticoid dexamethasone (0.1 micromol/l) over 4 days in cell culture increased the number of fractionated nuclei from 2 to 7 and 14%, respectively, an effect that was reversed by the glucocorticoid receptor antagonist RU486 (1 micromol/l). In INS-1 cells, dexamethasone increased the number of transferase-mediated dUTP nick-end labeling-staining positive cells, caspase-3 activity, and poly-(ADP-) ribose polymerase protein cleavage; decreased Bcl-2 transcript and protein abundance; dephosphorylated the proapoptotic protein of the Bcl-2 family (BAD) at serine155; and depolarized mitochondria. Dexamethasone increased PP-2B (calcineurin) activity, an effect abrogated by FK506. FK506 (0.1 micromol/l) and another calcineurin inhibitor, deltamethrin (1 micromol/l), attenuated dexamethasone-induced cell death. The stable glucagon-like peptide 1 analog, exendin-4 (10 nmol/l), inhibited dexamethasone-induced apoptosis in mouse beta-cells and INS-1 cells. The protective effect of exendin-4 was mimicked by forskolin (10 micromol/l) but not mimicked by guanine nucleotide exchange factor with the specific agonist 8CPT-Me-cAMP (50 micromol/l). Exendin-4 did not protect against cell death in the presence of cAMP-dependent protein kinase (PKA) inhibition by H89 (10 micromol/l) or KT5720 (5 micromol/l). In conclusion, glucocorticoid-induced apoptosis in insulin-secreting cells is accompanied by a downregulation of Bcl-2, activation of calcineurin with subsequent dephosphorylation of BAD, and mitochondrial depolarization. Exendin-4 protects against glucocorticoid-induced apoptosis, an effect mimicked by forskolin and reversed by PKA inhibitors.
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Affiliation(s)
- Felicia Ranta
- Institut für Physiologie, University of Tübingen, Gmelinstrasse 5, D-72076 Tübingen, Germany
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Fujinaka Y, Sipula D, Garcia-Ocaña A, Vasavada RC. Characterization of mice doubly transgenic for parathyroid hormone-related protein and murine placental lactogen: a novel role for placental lactogen in pancreatic beta-cell survival. Diabetes 2004; 53:3120-30. [PMID: 15561942 DOI: 10.2337/diabetes.53.12.3120] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Transgenic overexpression of either parathyroid hormone-related peptide (PTHrP) or mouse placental lactogen type 1 (mPL1) in pancreatic beta-cells, using the rat insulin II promoter (RIP), results in islet hyperplasia either through prolonged beta-cell survival or through increased beta-cell proliferation and hypertrophy, respectively. For determining whether the two proteins might exert complementary, additive, or synergistic effects on islet mass and function when simultaneously overexpressed in beta-cells in vivo, RIP-PTHrP and RIP-mPL1 mice were crossed to generate mice doubly transgenic for PTHrP and mPL1. These double-transgenic mice displayed marked islet hyperplasia (threefold), hypoglycemia, increased beta-cell proliferation (threefold), and resistance to the diabetogenic and cytotoxic effects of streptozotocin compared with their normal siblings. Although the phenotype of the double-transgenic mice was neither additive nor synergistic relative to their single-transgenic counterparts, it was indeed complementary, yielding the maximal salutary phenotypic features of both individual transgenes. Finally, mPL1, for the first time, was shown to exert a protective effect on the survival of beta-cells, placing it among the few proteins that can improve function and proliferation and prolong the survival of beta-cells. Placental lactogen 1 is an attractive target for future therapeutic strategies in diabetes.
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Affiliation(s)
- Yuichi Fujinaka
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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Gesina E, Tronche F, Herrera P, Duchene B, Tales W, Czernichow P, Breant B. Dissecting the role of glucocorticoids on pancreas development. Diabetes 2004; 53:2322-9. [PMID: 15331541 DOI: 10.2337/diabetes.53.9.2322] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To determine whether glucocorticoids are involved in pancreas development, glucocorticoid treatment of rat pancreatic buds in vitro was combined with the analysis of transgenic mice lacking the glucocorticoid receptor (GR) in specific pancreatic cells. In vitro treatment of embryonic pancreata with dexamethasone, a glucocorticoid agonist, induced a decrease of insulin-expressing cell numbers and a doubling of acinar cell area, indicating that glucocorticoids favored acinar differentiation; in line with this, expression of Pdx-1, Pax-6, and Nkx6.1 was downregulated, whereas the mRNA levels of Ptf1-p48 and Hes-1 were increased. The selective inactivation of the GR gene in insulin-expressing beta-cells in mice (using a RIP-Cre transgene) had no measurable consequences on beta- or alpha-cell mass, whereas the absence of GR in the expression domain of Pdx-1 (Pdx-Cre transgene) led to a twofold increased beta-cell mass, with increased islet numbers and size but normal alpha-cell mass in adults. These results demonstrate that glucocorticoids play an important role in pancreatic beta-cell lineage, acting before hormone gene expression onset and possibly also modulating the balance between endocrine and exocrine cell differentiation.
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Affiliation(s)
- Emilie Gesina
- INSERM U457, Hôpital Robert Debré, Paris F 75019, France
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Shao J, Qiao L, Friedman JE. Prolactin, progesterone, and dexamethasone coordinately and adversely regulate glucokinase and cAMP/PDE cascades in MIN6 beta-cells. Am J Physiol Endocrinol Metab 2004; 286:E304-10. [PMID: 14559722 DOI: 10.1152/ajpendo.00210.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Islet cells undergo major changes in structure and function to meet the demand for increased insulin secretion during pregnancy, but the nature of the hormonal interactions and signaling events is incompletely understood. Here, we used the glucose-responsive MIN6 beta-cell line treated with prolactin (PRL), progesterone (PRG), and dexamethasone (DEX, a synthetic glucocorticoid), all elevated during late pregnancy, to study their effects on mechanisms of insulin secretion. DEX alone or combined with PRL and PRG inhibited insulin secretion in response to 16 mM glucose-stimulating concentrations. However, in the basal state (3 mM glucose), the insulin levels in response to DEX treatment were unchanged, and the three hormones together maintained higher insulin release. There were no changes of protein levels of GLUT2 or glucokinase (GK), but PRL or PRG treatment increased GK activity, whereas DEX had an inhibitory effect on GK activity. alpha-Ketoisocaproate (alpha-KIC)-stimulated insulin secretion was also reduced by DEX alone or combined with PRL and PRG, suggesting that DEX may inhibit distal steps in the insulin-exocytotic process. PRL treatment increased the concentration of intracellular cAMP in response to 16 mM glucose, suggesting a role for cAMP in potentiation of insulin secretion, whereas DEX alone or combined with PRL and PRG reduced cAMP levels by increasing phosphodiesterase (PDE) activity. These data provide evidence that PRL and to a lesser extent PRG, which increase in early pregnancy, enhance basal and glucose-stimulated insulin secretion in part by increasing GK activity and amplifying cAMP levels. Glucocorticoid, which increases throughout gestation, counteracts only glucose-stimulated insulin secretion under high glucose concentrations by dominantly inhibiting GK activity and increasing PDE activity to reduce cAMP levels. These adaptations in the beta-cell may play an important role in maintaining the basal hyperinsulinemia of pregnancy while limiting the capacity of PRL and PRG to promote glucose-stimulated insulin secretion during late gestation.
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Affiliation(s)
- Jianhua Shao
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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Blondeau B, Lesage J, Czernichow P, Dupouy JP, Bréant B. Glucocorticoids impair fetal beta-cell development in rats. Am J Physiol Endocrinol Metab 2001; 281:E592-9. [PMID: 11500315 DOI: 10.1152/ajpendo.2001.281.3.e592] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In rats, poor fetal growth due to maternal food restriction during pregnancy is associated with decreased beta-cell mass at birth and glucose intolerance in adulthood. Overexposure to glucocorticoids in utero can induce intrauterine growth retardation in humans and animals and subsequent glucose intolerance in rodents. The aims of this study were to investigate whether glucocorticoid overexposure mediates the effect of undernutrition on beta-cell mass and to study their potential role in normally nourished rats. Undernutrition significantly increased maternal and fetal corticosterone levels. Twenty-one-day-old fetuses with undernutrition showed growth retardation and decreased pancreatic insulin content; adrenalectomy and subcutaneous corticosterone implants in their dams prevented the maternal corticosterone increase and restored fetal beta-cell mass. In fetuses with normal nutrition, fetal corticosterone levels were negatively correlated to fetal weight and insulin content; fetal beta-cell mass increased from 355 +/- 48 microg in sham to 516 +/- 160 microg after maternal adrenalectomy; inhibition of steroid production by metyrapone induced a further increase to 757 +/- 125 microg. Our data support the new concept of a negative role of glucocorticoids in fetal beta-cell development.
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Affiliation(s)
- B Blondeau
- Institut National de la Santé et de la Recherche Médicale Unité 457, Hôpital Robert Debré, 48 boulevard Sérurier, 75019 Paris, France
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