1
|
Luo W, Dai J, Liu J, Huang Y, Zheng Z, Xu P, Ma Y. PACAP attenuates hepatic lipid accumulation through the FAIM/AMPK/IRβ axis during overnutrition. Mol Metab 2022; 65:101584. [PMID: 36055580 PMCID: PMC9478455 DOI: 10.1016/j.molmet.2022.101584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/23/2022] [Accepted: 08/25/2022] [Indexed: 11/12/2022] Open
Abstract
Objective Pituitary adenylate cyclase-activating polypeptide (PACAP) was reported to attenuate hepatic lipid accumulation in overnutrition-related metabolic disorder, mediated by up-regulation of fas apoptosis inhibitory molecule (FAIM). However, how PACAP regulates FAIM in metabolic tissues remains to be addressed. Here we investigated the underlying mechanism on the role of PACAP in ameliorating metabolic disorder and examined the potential therapeutic effects of PACAP in preventing the progression of metabolic associated fatty liver disease (MAFLD). Methods Mouse models with MAFLD induced by high-fat diet were employed. Different doses of PACAP were intraperitoneally administrated. Western blot, luciferase assay, lentiviral-mediated gene manipulations and animal metabolic phenotyping analysis were performed to explore the signaling pathway involved in PACAP function. Results PACAP ameliorated the excessive hepatic lipid accumulation and inhibited lipogenesis in HFD-fed C57BL/6J mice. Mechanistically, PACAP activated the FAIM-AMPK-IRβ axis to inhibit the expression of lipid synthesis genes, and FAIM mediated the effects of PACAP. FAIM suppression via lentiviral-mediated shRNA inhibited the activation of AMPK, whereas FAIM overexpression promoted AMPK activation. PACAP increased the promoter activity of FAIM gene through activating PKA-CREB signaling pathway. Conclusion Our work demonstrated that the administration of PACAP represented a feasible approach for treating hepatic lipid accumulation in MAFLD. The findings reveal the molecular mechanism that PACAP increase FAIM expression and activates the FAIM/AMPK/IRβ signaling axis, thus inhibits lipogenesis to mediate its beneficial effects. PACAP ameliorates hepatic lipid accumulation through the AMPK pathway. AMPK is a downstream mediator of FAIM. FAIM is transcriptionally activated by CREB and regulated by PACAP. PACAP regulates the FAIM-AMPK-IRβ axis to treat fatty liver phenotype.
Collapse
Affiliation(s)
- Wei Luo
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China
| | - Jiaxin Dai
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China
| | - Jianmin Liu
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China
| | - Yongmei Huang
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China
| | - Ziqiong Zheng
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China
| | - Pei Xu
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China
| | - Yi Ma
- Department of Cellular Biology, Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, Guangzhou, China.
| |
Collapse
|
2
|
Protective Effects of PACAP in a Rat Model of Diabetic Neuropathy. Int J Mol Sci 2021; 22:ijms221910691. [PMID: 34639032 PMCID: PMC8509403 DOI: 10.3390/ijms221910691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/20/2021] [Accepted: 09/24/2021] [Indexed: 02/07/2023] Open
Abstract
Pituitary adenylate cyclase-activating peptide (PACAP) is a neuropeptide with a widespread occurrence and diverse effects. PACAP has well-documented neuro- and cytoprotective effects, proven in numerous studies. Among others, PACAP is protective in models of diabetes-associated diseases, such as diabetic nephropathy and retinopathy. As the neuropeptide has strong neurotrophic and neuroprotective actions, we aimed at investigating the effects of PACAP in a rat model of streptozotocin-induced diabetic neuropathy, another common complication of diabetes. Rats were treated with PACAP1-38 every second day for 8 weeks starting simultaneously with the streptozotocin injection. Nerve fiber morphology was examined with electron microscopy, chronic neuronal activation in pain processing centers was studied with FosB immunohistochemistry, and functionality was assessed by determining the mechanical nociceptive threshold. PACAP treatment did not alter body weight or blood glucose levels during the 8-week observation period. However, PACAP attenuated the mechanical hyperalgesia, compared to vehicle-treated diabetic animals, and it markedly reduced the morphological signs characteristic for neuropathy: axon–myelin separation, mitochondrial fission, unmyelinated fiber atrophy, and basement membrane thickening of endoneurial vessels. Furthermore, PACAP attenuated the increase in FosB immunoreactivity in the dorsal spinal horn and periaqueductal grey matter. Our results show that PACAP is a promising therapeutic agent in diabetes-associated complications, including diabetic neuropathy.
Collapse
|
3
|
Lipotoxic Impairment of Mitochondrial Function in β-Cells: A Review. Antioxidants (Basel) 2021; 10:antiox10020293. [PMID: 33672062 PMCID: PMC7919463 DOI: 10.3390/antiox10020293] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/06/2021] [Accepted: 02/11/2021] [Indexed: 02/08/2023] Open
Abstract
Lipotoxicity is a major contributor to type 2 diabetes mainly promoting mitochondrial dysfunction. Lipotoxic stress is mediated by elevated levels of free fatty acids through various mechanisms and pathways. Impaired peroxisome proliferator-activated receptor (PPAR) signaling, enhanced oxidative stress levels, and uncoupling of the respiratory chain result in ATP deficiency, while β-cell viability can be severely impaired by lipotoxic modulation of PI3K/Akt and mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK) pathways. However, fatty acids are physiologically required for an unimpaired β-cell function. Thus, preparation, concentration, and treatment duration determine whether the outcome is beneficial or detrimental when fatty acids are employed in experimental setups. Further, ageing is a crucial contributor to β-cell decay. Cellular senescence is connected to loss of function in β-cells and can further be promoted by lipotoxicity. The potential benefit of nutrients has been broadly investigated, and particularly polyphenols were shown to be protective against both lipotoxicity and cellular senescence, maintaining the physiology of β-cells. Positive effects on blood glucose regulation, mitigation of oxidative stress by radical scavenging properties or regulation of antioxidative enzymes, and modulation of apoptotic factors were reported. This review summarizes the significance of lipotoxicity and cellular senescence for mitochondrial dysfunction in the pancreatic β-cell and outlines potential beneficial effects of plant-based nutrients by the example of polyphenols.
Collapse
|
4
|
Toth D, Szabo E, Tamas A, Juhasz T, Horvath G, Fabian E, Opper B, Szabo D, Maugeri G, D'Amico AG, D'Agata V, Vicena V, Reglodi D. Protective Effects of PACAP in Peripheral Organs. Front Endocrinol (Lausanne) 2020; 11:377. [PMID: 32765418 PMCID: PMC7381171 DOI: 10.3389/fendo.2020.00377] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 05/12/2020] [Indexed: 12/21/2022] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide widely distributed in the nervous system, where it exerts strong neuroprotective effects. PACAP is also expressed in peripheral organs but its peripheral protective effects have not been summarized so far. Therefore, the aim of the present paper is to review the existing literature regarding the cytoprotective effects of PACAP in non-neuronal cell types, peripheral tissues, and organs. Among others, PACAP has widespread expression in the digestive system, where it shows protective effects in various intestinal pathologies, such as duodenal ulcer, small bowel ischemia, and intestinal inflammation. PACAP is present in both the exocrine and endocrine pancreas as well as liver where it reduces inflammation and steatosis by interfering with hepatic pathology related to obesity. It is found in several exocrine glands and also in urinary organs, where, with its protective effects being mainly published regarding renal pathologies, PACAP is protective in numerous conditions. PACAP displays anti-inflammatory effects in upper and lower airways of the respiratory system. In the skin, it is involved in the development of inflammatory pathology such as psoriasis and also has anti-allergic effects in a model of contact dermatitis. In the non-neuronal part of the visual system, PACAP showed protective effects in pathological conditions of the cornea and retinal pigment epithelial cells. The positive role of PACAP has been demonstrated on the formation and healing processes of cartilage and bone where it also prevents osteoarthritis and rheumatoid arthritis development. The protective role of PACAP was also demonstrated in the cardiovascular system in different pathological processes including hyperglycaemia-induced endothelial dysfunction and age-related vascular changes. In the heart, PACAP protects against ischemia, oxidative stress, and cardiomyopathies. PACAP is also involved in the protection against the development of pre-senile systemic amyloidosis, which is presented in various peripheral organs in PACAP-deficient mice. The studies summarized here provide strong evidence for the cytoprotective effects of the peptide. The survival-promoting effects of PACAP depend on a number of factors which are also shortly discussed in the present review.
Collapse
Affiliation(s)
- Denes Toth
- Department of Forensic Medicine, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Edina Szabo
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Andrea Tamas
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Tamas Juhasz
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Biomedical and Biotechnological Sciences, Section of Human Anatomy and Histology, University of Catania, Catania, Italy
| | - Gabriella Horvath
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Eszter Fabian
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Balazs Opper
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Dora Szabo
- Heart Institute, Medical School, University of Pécs, Pécs, Hungary
| | - Grazia Maugeri
- Department of Biomedical and Biotechnological Sciences, Section of Human Anatomy and Histology, University of Catania, Catania, Italy
| | - Agata G. D'Amico
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Velia D'Agata
- Department of Biomedical and Biotechnological Sciences, Section of Human Anatomy and Histology, University of Catania, Catania, Italy
| | - Viktoria Vicena
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
| | - Dora Reglodi
- Department of Anatomy, MTA-PTE PACAP Research Team, University of Pécs Medical School, Pécs, Hungary
- *Correspondence: Dora Reglodi
| |
Collapse
|
5
|
The Neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) is Protective in Inflammation and Oxidative Stress-Induced Damage in the Kidney. Int J Mol Sci 2019; 20:ijms20194944. [PMID: 31591326 PMCID: PMC6801442 DOI: 10.3390/ijms20194944] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 09/20/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022] Open
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic neuropeptide with a widespread distribution throughout the entire body including the urinary system. PACAP exerts protective actions in different injury models related to several organ systems. Its protective effect is mainly based on its antiapoptotic, anti-inflammatory and antioxidant effects. The present review aims to summarize the effects of PACAP in pathologies associated with inflammation and oxidative stress-induced damage in the kidney. Both in vitro and in vivo data are available proving its protective actions against oxidative stress, hypoxia, renal ischemia/reperfusion, diabetic nephropathy, myeloma kidney injury, amyloidosis and different types of drug-induced nephropathies. Data showing the nephroprotection by PACAP emphasize the potential of PACAP’s therapeutic use in various renal pathologies.
Collapse
|
6
|
Denes V, Geck P, Mester A, Gabriel R. Pituitary Adenylate Cyclase-Activating Polypeptide: 30 Years in Research Spotlight and 600 Million Years in Service. J Clin Med 2019; 8:jcm8091488. [PMID: 31540472 PMCID: PMC6780647 DOI: 10.3390/jcm8091488] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/02/2019] [Accepted: 09/10/2019] [Indexed: 12/12/2022] Open
Abstract
Emerging from the depths of evolution, pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors (i.e., PAC1, VPAC1, VPAC2) are present in multicellular organisms from Tunicates to humans and govern a remarkable number of physiological processes. Consequently, the clinical relevance of PACAP systems spans a multifaceted palette that includes more than 40 disorders. We aimed to present the versatility of PACAP1-38 actions with a focus on three aspects: (1) when PACAP1-38 could be a cause of a malfunction, (2) when PACAP1-38 could be the cure for a malfunction, and (3) when PACAP1-38 could either improve or impair biology. PACAP1-38 is implicated in the pathophysiology of migraine and post-traumatic stress disorder whereas an outstanding protective potential has been established in ischemia and in Alzheimer’s disease. Lastly, PACAP receptors could mediate opposing effects both in cancers and in inflammation. In the light of the above, the duration and concentrations of PACAP agents must be carefully set at any application to avoid unwanted consequences. An enormous amount of data accumulated since its discovery (1989) and the first clinical trials are dated in 2017. Thus in the field of PACAP research: “this is not the end, not even the beginning of the end, but maybe the end of the beginning.”
Collapse
Affiliation(s)
- Viktoria Denes
- Department of Experimental Zoology and Neurobiology, University of Pécs, 7624 Pécs, Hungary.
| | - Peter Geck
- Department of Immunology, School of Medicine, Tufts University, Boston, MA 02111, USA.
| | - Adrienn Mester
- Department of Experimental Zoology and Neurobiology, University of Pécs, 7624 Pécs, Hungary.
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pécs, 7624 Pécs, Hungary.
| |
Collapse
|
7
|
Fu J, Cui Q, Yang B, Hou Y, Wang H, Xu Y, Wang D, Zhang Q, Pi J. The impairment of glucose-stimulated insulin secretion in pancreatic β-cells caused by prolonged glucotoxicity and lipotoxicity is associated with elevated adaptive antioxidant response. Food Chem Toxicol 2016; 100:161-167. [PMID: 28027979 DOI: 10.1016/j.fct.2016.12.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/06/2016] [Accepted: 12/14/2016] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes (T2D) is a progressive disease characterized by sustained hyperglycemia and is frequently accompanied by hyperlipidemia. Deterioration of β-cell function in T2D patients may be caused, in part, by long-term exposure to high concentrations of glucose and/or lipids. We developed systems to study how chronic glucotoxicity and lipotoxicity might be linked to the impairment of glucose-stimulated insulin secretion (GSIS) machinery in pancreatic β-cells. INS-1 (832/13) were exposed to glucose and/or palmitate for up to 10 weeks. Chronic high glucose and/or palmitate exposure resulted in impaired GSIS accompanied by a dramatic increase in oxidative stress, as determined by basal intracellular peroxide levels. In addition, the GSIS-associated reactive oxygen species (ROS) signals, assessed as glucose-stimulated peroxide accumulation positively correlated with GSIS in glucose- and/or palmitate-exposed cells, as well as glucose-stimulated reductions in GSH/GSSG ratios. Furthermore, the impairment of GSIS caused by chronic high glucose and/or palmitate exposures were attributed to the induction of adaptive antioxidant response and mitochondrial uncoupling, which negatively regulates glucose-derived ROS generation. Taken together, persistent glucotoxicity- and/or lipotoxicity-mediated oxidative stress and subsequent adaptive antioxidant response impair glucose-derived ROS signaling and GSIS in pancreatic β-cells.
Collapse
Affiliation(s)
- Jingqi Fu
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Qi Cui
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Bei Yang
- Department of Histology and Embryology, School of Basic Medical Sciences, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Yongyong Hou
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Huihui Wang
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Yuanyuan Xu
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China
| | - Difei Wang
- The First Affiliated Hospital, China Medical University, 155 Nanjingbei Street, Heping District, Shenyang, Liaoning, 110001, PR China
| | - Qiang Zhang
- Department of Environmental Health, Rollins School of Public Health, Emory University, 201 Dowman Drive, Atlanta, GA, 30322, USA
| | - Jingbo Pi
- Program of Environmental Toxicology, School of Public Health, China Medical University No 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning, 110122, PR China.
| |
Collapse
|
8
|
|
9
|
Li E, Nakata M, Shinozaki A, Yang Y, Zhang B, Yada T. Betatrophin expression is promoted in obese hyperinsulinemic type 2 but not type 1 diabetic mice. Endocr J 2016; 63:611-9. [PMID: 27097546 DOI: 10.1507/endocrj.ej16-0164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Regeneration of pancreatic β-cell mass benefits both type 1 and type 2 diabetic patients. A recent study identified betatrophin as a β-cell proliferation factor. However, the expressional regulation of betatrophin remains less defined. In this study, we aimed to clarify the regulation of betatrophin expression in obese type 2 vs. type 1 diabetes model animals. We experimented type 2 diabetes models, diet-induced-obesity (DIO) mice and db/db mice, and type 1 diabetes models, C57B6 mice receiving streptozotocin (STZ) or 70% pancreatectomy to destroy or remove β-cells. Serum betatrophin levels and betatrophin mRNA expressions in the liver, white adipose tissue (WAT) and brown adipose tissue (BAT) were measured. In DIO mice and db/db mice, serum betatrophin and betatrophin mRNA expressions in the liver, WAT and BAT were elevated in parallel with increases in body weight and plasma insulin. These elevated betatrophin mRNA expressions were not altered by treatment with SGLT2 inhibitor that ameliorated hyperglycemia. In pancreatectomized mice, betatrophin expression in WAT decreased in parallel with reductions in weight and insulin. In STZ-treated mice, betatrophin expressions in the liver, WAT and BAT were reduced. However, when the mouse liver slices were cultured with STZ, betatrophin expression was significantly reduced, indicating a direct action of STZ on the liver. These results indicate that the expression of betatrophin is upregulated in the liver, WAT and BAT in obese hyperinsulinemic type 2 diabetes but decreased in WAT in hypoinsulinemic type 1 diabetes, suggesting its positive correlation with body weight and plasma insulin but not blood glucose.
Collapse
MESH Headings
- Adipose Tissue, Brown/metabolism
- Adipose Tissue, Brown/pathology
- Adipose Tissue, White/metabolism
- Adipose Tissue, White/pathology
- Angiopoietin-Like Protein 8
- Angiopoietin-like Proteins
- Animals
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/pathology
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/pathology
- Hyperinsulinism/complications
- Hyperinsulinism/genetics
- Hyperinsulinism/pathology
- Liver/metabolism
- Liver/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Obese
- Obesity/complications
- Obesity/genetics
- Obesity/pathology
- Peptide Hormones/genetics
- Peptide Hormones/metabolism
Collapse
Affiliation(s)
- EnXu Li
- Department of Physiology, Division of Integrative Physiology, Jichi Medical University School of Medicine, Shimotsuke 329-0498, Japan
| | | | | | | | | | | |
Collapse
|
10
|
IL-10 gene transfer upregulates arcuate POMC and ameliorates hyperphagia, obesity and diabetes by substituting for leptin. Int J Obes (Lond) 2015; 40:425-33. [DOI: 10.1038/ijo.2015.201] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 08/25/2015] [Accepted: 08/30/2015] [Indexed: 11/08/2022]
|
11
|
Di Cairano ES, Moretti S, Marciani P, Sacchi VF, Castagna M, Davalli A, Folli F, Perego C. Neurotransmitters and Neuropeptides: New Players in the Control of Islet of Langerhans' Cell Mass and Function. J Cell Physiol 2015; 231:756-67. [PMID: 26332080 DOI: 10.1002/jcp.25176] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/27/2015] [Indexed: 12/19/2022]
Abstract
Islets of Langerhans control whole body glucose homeostasis, as they respond, releasing hormones, to changes in nutrient concentrations in the blood stream. The regulation of hormone secretion has been the focus of attention for a long time because it is related to many metabolic disorders, including diabetes mellitus. Endocrine cells of the islet use a sophisticate system of endocrine, paracrine and autocrine signals to synchronize their activities. These signals provide a fast and accurate control not only for hormone release but also for cell differentiation and survival, key aspects in islet physiology and pathology. Among the different categories of paracrine/autocrine signals, this review highlights the role of neurotransmitters and neuropeptides. In a manner similar to neurons, endocrine cells synthesize, accumulate, release neurotransmitters in the islet milieu, and possess receptors able to decode these signals. In this review, we provide a comprehensive description of neurotransmitter/neuropetide signaling pathways present within the islet. Then, we focus on evidence supporting the concept that neurotransmitters/neuropeptides and their receptors are interesting new targets to preserve β-cell function and mass. A greater understanding of how this network of signals works in physiological and pathological conditions would advance our knowledge of islet biology and physiology and uncover potentially new areas of pharmacological intervention. J. Cell. Physiol. 231: 756-767, 2016. © 2015 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Eliana S Di Cairano
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Stefania Moretti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Paola Marciani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Vellea Franca Sacchi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Michela Castagna
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| | - Alberto Davalli
- Department of Internal Medicine, Diabetes and Endocrinology Unit, San Raffaele Scientific Institute, Milan, Italy
| | - Franco Folli
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center at San Antonio, Texas.,Department of Internal Medicine, Obesity and Comorbidities Research Center (OCRC), University of Campinas, UNICAMP, Campinas, Sao Paulo State, Brazil
| | - Carla Perego
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Laboratory of Molecular and Cellular Physiology, Universit, à, degli Studi di Milano, Milan, Italy
| |
Collapse
|
12
|
Hoffmann A, Spengler D. Role of ZAC1 in transient neonatal diabetes mellitus and glucose metabolism. World J Biol Chem 2015; 6:95-109. [PMID: 26322169 PMCID: PMC4549774 DOI: 10.4331/wjbc.v6.i3.95] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/19/2015] [Accepted: 07/11/2015] [Indexed: 02/05/2023] Open
Abstract
Transient neonatal diabetes mellitus 1 (TNDM1) is a rare genetic disorder representing with severe neonatal hyperglycaemia followed by remission within one and a half year and adolescent relapse with type 2 diabetes in half of the patients. Genetic defects in TNDM1 comprise uniparental isodisomy of chromosome 6, duplication of the minimal TNDM1 locus at 6q24, or relaxation of genomically imprinted ZAC1/HYMAI. Whereas the function of HYMAI, a non-coding mRNA, is still unidentified, biochemical and molecular studies show that zinc finger protein 1 regulating apoptosis and cell cycle arrest (ZAC1) behaves as a factor with versatile transcriptional functions dependent on binding to specific GC-rich DNA motives and interconnected regulation of recruited coactivator activities. Genome-wide expression profiling enabled the isolation of a number of Zac1 target genes known to regulate different aspects of β-cell function and peripheral insulin sensitivity. Among these, upregulation of Pparγ and Tcf4 impairs insulin-secretion and β-cell proliferation. Similarly, Zac1-mediated upregulation of Socs3 may attenuate β-cell proliferation and survival by inhibition of growth factor signalling. Additionally, Zac1 directly represses Pac1 and Rasgrf1 with roles in insulin secretion and β-cell proliferation. Collectively, concerted dysregulation of these target genes could contribute to the onset and course of TNDM1. Interestingly, Zac1 overexpression in β-cells spares the effects of stimulatory G-protein signaling on insulin secretion and raises the prospect for tailored treatments in relapsed TNDM1 patients. Overall, these results suggest that progress on the molecular and cellular foundations of monogenetic forms of diabetes can advance personalized therapy in addition to deepening the understanding of insulin and glucose metabolism in general.
Collapse
|
13
|
Kozuka C, Sunagawa S, Ueda R, Higa M, Ohshiro Y, Tanaka H, Shimizu-Okabe C, Takayama C, Matsushita M, Tsutsui M, Ishiuchi S, Nakata M, Yada T, Miyazaki JI, Oyadomari S, Shimabukuro M, Masuzaki H. A novel insulinotropic mechanism of whole grain-derived γ-oryzanol via the suppression of local dopamine D 2 receptor signalling in mouse islet. Br J Pharmacol 2015; 172:4519-4534. [PMID: 26140534 DOI: 10.1111/bph.13236] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/16/2015] [Accepted: 06/20/2015] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE γ-Oryzanol, derived from unrefined rice, attenuated the preference for dietary fat in mice, by decreasing hypothalamic endoplasmic reticulum stress. However, no peripheral mechanisms, whereby γ-oryzanol could ameliorate glucose dyshomeostasis were explored. Dopamine D2 receptor signalling locally attenuates insulin secretion in pancreatic islets, presumably via decreased levels of intracellular cAMP. We therefore hypothesized that γ-oryzanol would improve high-fat diet (HFD)-induced dysfunction of islets through the suppression of local D2 receptor signalling. EXPERIMENTAL APPROACH Glucose metabolism and regulation of molecules involved in D2 receptor signalling in pancreatic islets were investigated in male C57BL/6J mice, fed HFD and treated with γ-oryzanol . In isolated murine islets and the beta cell line, MIN6 , the effects of γ-oryzanol on glucose-stimulated insulin secretion (GSIS) was analysed using siRNA for D2 receptors and a variety of compounds which alter D2 receptor signalling. KEY RESULTS In islets, γ-oryzanol enhanced GSIS via the activation of the cAMP/PKA pathway. Expression of molecules involved in D2 receptor signalling was increased in islets from HFD-fed mice, which were reciprocally decreased by γ-oryzanol. Experiments with siRNA for D2 receptors and D2 receptor ligands in vitro suggest that γ-oryzanol suppressed D2 receptor signalling and augmented GSIS. CONCLUSIONS AND IMPLICATIONS γ-Oryzanol exhibited unique anti-diabetic properties. The unexpected effects of γ-oryzanol on D2 receptor signalling in islets may provide a novel; natural food-based, approach to anti-diabetic therapy.
Collapse
Affiliation(s)
- Chisayo Kozuka
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan
| | - Sumito Sunagawa
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan
| | - Rei Ueda
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan
| | - Moritake Higa
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan.,The Diabetes and Life-Style Related Disease Center, Tomishiro Central Hospital, Okinawa, Japan
| | - Yuzuru Ohshiro
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan.,Okinawa Daiichi Hospital, Okinawa, Japan
| | - Hideaki Tanaka
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan.,Tanaka Clinic, Okinawa, Japan
| | - Chigusa Shimizu-Okabe
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Chitoshi Takayama
- Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Masayuki Matsushita
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Masato Tsutsui
- Department of Pharmacology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Shogo Ishiuchi
- Department of Neurosurgery, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Masanori Nakata
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Toshihiko Yada
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Jun-Ichi Miyazaki
- Division of Stem Cell Regulation Research, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Seiichi Oyadomari
- Institute for Genome Research, University of Tokushima, Tokushima, Japan
| | - Michio Shimabukuro
- Department of Cardio-Diabetes Medicine, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Hiroaki Masuzaki
- Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology (Second Department of Internal Medicine), University of the Ryukyus, Okinawa, Japan
| |
Collapse
|
14
|
Higashi S, Katagi K, Shintani N, Ikeda K, Sugimoto Y, Tsuchiya S, Inoue N, Tanaka S, Koumoto M, Kasai A, Nakazawa T, Hayata-Takano A, Hamagami KI, Tomimoto S, Yoshida T, Ohkubo T, Nagayasu K, Ago Y, Onaka Y, Hashimoto R, Ichikawa A, Baba A, Hashimoto H. p13 overexpression in pancreatic β-cells ameliorates type 2 diabetes in high-fat-fed mice. Biochem Biophys Res Commun 2015; 461:612-7. [DOI: 10.1016/j.bbrc.2015.04.074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 04/14/2015] [Indexed: 12/30/2022]
|
15
|
Prevost G, Arabo A, Jian L, Quelennec E, Cartier D, Hassan S, Falluel-Morel A, Tanguy Y, Gargani S, Lihrmann I, Kerr-Conte J, Lefebvre H, Pattou F, Anouar Y. The PACAP-regulated gene selenoprotein T is abundantly expressed in mouse and human β-cells and its targeted inactivation impairs glucose tolerance. Endocrinology 2013; 154:3796-806. [PMID: 23913443 DOI: 10.1210/en.2013-1167] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Selenoproteins are involved in the regulation of redox status, which affects several cellular processes, including cell survival and homeostasis. Considerable interest has arisen recently concerning the role of selenoproteins in the regulation of glucose metabolism. Here, we found that selenoprotein T (SelT), a new thioredoxin-like protein of the endoplasmic reticulum, is present at high levels in human and mouse pancreas as revealed by immunofluorescence and quantitative PCR. Confocal immunohistochemistry studies revealed that SelT is mostly confined to insulin- and somatostatin-producing cells in mouse and human islets. To elucidate the role of SelT in β-cells, we generated, using a Cre-Lox strategy, a conditional pancreatic β-cell SelT-knockout C57BL/6J mice (SelT-insKO) in which SelT gene disruption is under the control of the rat insulin promoter Cre gene. Glucose administration revealed that male SelT-insKO mice display impaired glucose tolerance. Although insulin sensitivity was not modified in the mutant mice, the ratio of glucose to insulin was significantly higher in the SelT-insKO mice compared with wild-type littermates, pointing to a deficit in insulin production/secretion in mutant mice. In addition, morphometric analysis showed that islets from SelT-insKO mice were smaller and that their number was significantly increased compared with islets from their wild-type littermates. Finally, we found that SelT is up-regulated by pituitary adenylate cyclase-activating polypeptide (PACAP) in β-pancreatic cells and that SelT could act by facilitating a feed-forward mechanism to potentiate insulin secretion induced by the neuropeptide. Our findings are the first to show that the PACAP-regulated SelT is localized in pancreatic β- and δ-cells and is involved in the control of glucose homeostasis.
Collapse
Affiliation(s)
- Gaëtan Prevost
- INSERM U982, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Sciences Faculty, University of Rouen, Place Emile Blondel, 76 821 Mont-Saint-Aignan cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Shao S, Yang Y, Yuan G, Zhang M, Yu X. Signaling molecules involved in lipid-induced pancreatic beta-cell dysfunction. DNA Cell Biol 2013; 32:41-9. [PMID: 23347443 DOI: 10.1089/dna.2012.1874] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The increasing incidence of type 2 diabetes mellitus is partially due to the rising obesity rates and the elevated levels of free fatty acids (FFAs). It is known that FFAs are putative mediators of beta-cell dysfunction, which is characterized with impaired glucose-stimulated insulin secretion and increased apoptosis, being defined as lipotoxicity. To date, many factors and their related signal pathways have been reported to be involved in FFA-induced beta-cell dysfunction. However, the entire blueprint is still not obtained. Some essential and newfound effectors, including the sterol regulatory element-binding protein (SREBP)-1c, farnesoid X receptor (FXR), forkhead box-containing protein O (FoxO) 1, ubiquitin C-terminal hydrolase L (UCHL) 1, N-myc downstream-regulated gene (NDRG) 2, perilipin family proteins, silent information regulator 2 protein 1 (Sirt1), pituitary adenylate cyclase-activating polypeptide (PACAP), and ghrelin are described in this review, which may help to further understand the molecular network for lipotoxicity.
Collapse
Affiliation(s)
- Shiying Shao
- Division of Endocrinology, Tongji Hospital, Tongji Medical College of Huazhong University of Science & Technology, Wuhan, People's Republic of China
| | | | | | | | | |
Collapse
|
17
|
Inoue H, Shintani N, Sakurai Y, Higashi S, Hayata-Takano A, Baba A, Hashimoto H. PACAP Inhibits β-cell Mass Expansion in a Mouse Model of Type II Diabetes: Persistent Suppressive Effects on Islet Density. Front Endocrinol (Lausanne) 2013; 4:27. [PMID: 23483824 PMCID: PMC3593608 DOI: 10.3389/fendo.2013.00027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 02/22/2013] [Indexed: 12/24/2022] Open
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a potent insulinotropic G-protein-coupled receptor ligand, for which morphoregulative roles in pancreatic islets have recently been suggested. Here, we evaluated the effects of pancreatic overexpression of PACAP on morphometric changes of islets in a severe type II diabetes model. Following cross-breeding of obese-diabetic model KKA(y) mice with mice overexpressing PACAP in their pancreatic β-cells, the resulting KKA(y) mice with or without PACAP transgene (PACAP/+:A(y)/+ or A(y)/+ mice) were fed with a high-fat diet up to the age of 11 months. Pancreatic sections from 5- to 11-month-old littermates were examined. Histomorphometric analyses revealed significant suppression of islet mass expansion in PACAP/+:A(y)/+ mice compared with A(y)/+ mice at 11 months, but no significant difference between PACAP/+ and +/+ (wild-type) mice, as previously reported. The suppressed islet mass in PACAP/+:A(y)/+ mice was due to a decrease in islet density but not islet size. In addition, the density of tiny islets (<0.001 mm(2)) and of insulin-positive clusters in ductal structures were markedly decreased in PACAP/+:A(y)/+ mice compared with A(y)/+ mice at 5 months of age. In contrast, PACAP overexpression caused no significant effects on the level of aldehyde-fuchsin reagent staining (a measure of β-cell granulation) or the volume and localization of glucagon-positive cells in the pancreas. These results support previously reported inhibitory effects of PACAP on pancreatic islet mass expansion, and suggest it has persistent suppressive effects on pancreatic islet density which may be related with ductal cell-associated islet neogenesis in type II diabetes.
Collapse
Affiliation(s)
- Hiroaki Inoue
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
| | - Norihito Shintani
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
| | - Yusuke Sakurai
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
- Japan Society for the Promotion of ScienceTokyo, Japan
| | - Shintaro Higashi
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
- Japan Society for the Promotion of ScienceTokyo, Japan
| | - Atsuko Hayata-Takano
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
- Department of Experimental Disease Model, Molecular Research Center for Children’s Mental Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of FukuiSuita, Osaka, Japan
| | - Akemichi Baba
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
- School of Pharmacy, Hyogo University of Health SciencesKobe, Hyogo, Japan
| | - Hitoshi Hashimoto
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka UniversitySuita, Osaka, Japan
- Department of Experimental Disease Model, Molecular Research Center for Children’s Mental Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of FukuiSuita, Osaka, Japan
- *Correspondence: Hitoshi Hashimoto, Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan. e-mail:
| |
Collapse
|
18
|
Luo G, Kong X, Lu L, Xu X, Wang H, Ma X. Glucagon-like peptide 1 potentiates glucotoxicity-diminished insulin secretion via stimulation of cAMP-PKA signaling in INS-1E cells and mouse islets. Int J Biochem Cell Biol 2012; 45:483-90. [PMID: 23220045 DOI: 10.1016/j.biocel.2012.11.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/12/2012] [Accepted: 11/25/2012] [Indexed: 01/01/2023]
Abstract
Glucagon-like peptide-1 (GLP-1)-enhanced insulin secretion is mainly mediated by cAMP-PKA and cAMP-Epac2 signaling pathways at physiological glucose concentrations. However the cellular mechanisms underlying the insulinotropic action of GLP-1 at glucotoxicity remain largely unknown. In the present study, we examined the effects of GLP-1 on glucotoxicity-diminished insulin secretion and explored the roles of these two cAMP-linked pathways in mediating the effects of GLP-1 under glucotoxic conditions. Consistent with the previous reports, exposure of INS-1E cells and mouse islets to 30 mM glucose for 72 h almost abolished glucose-stimulated insulin secretion. Addition of 10nM GLP-1 significantly increased glucose-stimulated insulin secretion. This was not due to a protective effect of GLP-1 against glucotoxicity-induced apoptosis but instead improvement of the secretory capacity of the insulin-secreting β-cells. It is of note that GLP-1 preferentially increased the expression and activity of PKA, whereas had no effects on Epac2 at high glucose. In correlation with the observations, treatment of INS-1E cells with the specific PKA inhibitor Rp-cAMPS completely abolished the insulinotropic action of GLP-1, whereas knock-down of Epac2 did not interfere the effects of GLP-1. Moreover, GLP-1 did not increase further insulin secretion in the presence of the PKA agonist 6-Bnz-cAMP-AM. By contrast, it produced additional enhancement of insulin secretion when Epac2 was maximally stimulated by its selective agonist 8-pCPT-2'-O-Me-cAMP-AM. Taken together, our results suggest that GLP-1 potentiates glucotoxicity-diminished insulin secretion mainly through cAMP-PKA signaling pathway.
Collapse
Affiliation(s)
- Guochun Luo
- Shenzhen University Diabetes Centre, Shenzhen 518060, PR China
| | | | | | | | | | | |
Collapse
|
19
|
Sanlioglu AD, Karacay B, Balci MK, Griffith TS, Sanlioglu S. Therapeutic potential of VIP vs PACAP in diabetes. J Mol Endocrinol 2012; 49:R157-67. [PMID: 22991228 DOI: 10.1530/jme-12-0156] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes (T2D) is characterized by chronic insulin resistance and a progressive decline in beta-cell function. Although rigorous glucose control can reduce morbidity and mortality associated with diabetes, achieving optimal long-term glycemic control remains to be accomplished in many diabetic patients. As beta-cell mass and function inevitably decline in T2D, exogenous insulin administration is almost unavoidable as a final outcome despite the use of oral antihyperglycemic agents in many diabetic patients. Pancreatic islet cell death, but not the defect in new islet formation or beta-cell replication, has been blamed for the decrease in beta-cell mass observed in T2D patients. Thus, therapeutic approaches designed to protect islet cells from apoptosis could significantly improve the management of T2D, because of its potential to reverse diabetes not just ameliorate glycemia. Therefore, an ideal beta-cell-preserving agent is expected to protect beta cells from apoptosis and stimulate postprandial insulin secretion along with increasing beta-cell replication and/or islet neogenesis. One such potential agent, the islet endocrine neuropeptide vasoactive intestinal peptide (VIP) strongly stimulates postprandial insulin secretion. Because of its broad spectrum of biological functions such as acting as a potent anti-inflammatory factor through suppression of Th1 immune response, and induction of immune tolerance via regulatory T cells, VIP has emerged as a promising therapeutic agent for the treatment of many autoimmune diseases including diabetes.
Collapse
Affiliation(s)
- Ahter D Sanlioglu
- Human Gene and Cell Therapy Center, Akdeniz University Hospitals and Clinics, B Block, 1st floor, Campus, Antalya 07058, Turkey
| | | | | | | | | |
Collapse
|
20
|
Cao M, Tong Y, Lv Q, Chen X, Long Y, Jiang L, Wan J, Zhang Y, Zhang F, Tong N. PPARδ Activation Rescues Pancreatic β-Cell Line INS-1E from Palmitate-Induced Endoplasmic Reticulum Stress through Enhanced Fatty Acid Oxidation. PPAR Res 2012; 2012:680684. [PMID: 22792088 PMCID: PMC3388384 DOI: 10.1155/2012/680684] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 04/10/2012] [Accepted: 04/12/2012] [Indexed: 02/05/2023] Open
Abstract
One of the key factors responsible for the development of type 2 diabetes is the loss of functional pancreatic β cells. This occurs due to a chronic exposure to a high fatty acid environment. ER stress is caused by an accumulation of irreversible misfold or unfold protein: these trigger the death of functional pancreatic β cells. PPARδ is an orphan nuclear receptor. It plays a pivotal role in regulating the metabolism of dietary lipids and fats. However, the correlation between PPARδ of fatty acids and ER stress of pancreatic β cells is not quite clear till date. Here, we show that PPARδ attenuates palmitate-induced ER stress of pancreatic β cells. On the other hand, PPARδ agonist inhibits both abnormal changes in ER structure and activation of signaling cascade, which is downstream ER stress. Further, we illustrate that PPARδ attenuates palmitate-induced ER stress by promoting fatty acid oxidation through treatment with etomoxir, an inhibitor of fatty acid oxidation. It dramatically abolishes PPARδ-mediated inhibition of ER stress. Finally, we show that PPARδ could protect pancreatic β cells from palmitate-induced cell death and dysfunction of insulin secretion. Our work elucidates the protective effect of PPARδ on the fatty-acid-induced toxicity of pancreatic β cells.
Collapse
Affiliation(s)
- Mingming Cao
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Yuzhen Tong
- School of Clinical Medicine, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Qingguo Lv
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Xiang Chen
- Research Laboratory of Endocrine and Metabolic Diseases, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yang Long
- Research Laboratory of Endocrine and Metabolic Diseases, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Li Jiang
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Jun Wan
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Yuwei Zhang
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Fang Zhang
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| | - Nanwei Tong
- Division of Endocrinology, West China Hospital, Sichuan University, 37 Guoxuexiang, Chengdu 610041, China
| |
Collapse
|
21
|
PACAP is an Endogenous Protective Factor—Insights from PACAP-Deficient Mice. J Mol Neurosci 2012; 48:482-92. [DOI: 10.1007/s12031-012-9762-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 03/22/2012] [Indexed: 01/07/2023]
|
22
|
Mansouri S, Ortsäter H, Pintor Gallego O, Darsalia V, Sjöholm A, Patrone C. Pituitary adenylate cyclase-activating polypeptide counteracts the impaired adult neural stem cell viability induced by palmitate. J Neurosci Res 2011; 90:759-68. [PMID: 22183970 DOI: 10.1002/jnr.22803] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 08/30/2011] [Indexed: 12/30/2022]
Abstract
Diabetes and obesity are characterized by hyperlipidemia and represent risk factors for premature neurological disorders. Diabetic/obese animals have impaired adult neurogenesis. We hypothesize that lipotoxicity leading to neurogenesis impairment plays a role in the development of neurological complications. If so, normalizing neurogenesis in diabetes/obesity could be therapeutically useful in counteracting neurological dysfunction. The goal of this study was to determine the potential of pituitary adenylate cyclase-activating polypeptide (PACAP) to protect adult neural stem cells (NSCs) from lipotoxicity and to study the expression of PACAP receptors in NSCs under lipotoxic conditions in vitro and in the subventricular zone in vivo. The viability of NSCs isolated from the adult mouse brain subventricular zone was assessed in the presence of a high-fat milieu, as mimicked by palmitate, which characterizes diabetic lipotoxicity. Regulation studies of PACAP receptors were performed by quantitative PCR on NSCs in vitro or on subventricular tissues isolated from obese ob/ob mice and their lean littermates. We show that palmitate impairs NSC viability by promoting lipoapoptosis. We also show that PACAP counteracts lipotoxicity via PAC-1 receptor activation. Studies on PACAP receptor expression revealed that PAC-1 and VPAC-2 are expressed by NSC in vitro and are upregulated by palmitate treatment and that PAC-1, VPAC-1, and VPAC-2 are expressed in the subventricular zone/striatum in vivo and are upregulated in ob/ob mice. The present study reveals a previously uncharacterized role of PACAP to protect NSC from lipotoxicity and suggests a potential therapeutic role for PACAP receptor agonists in the treatment of neurological complications in obesity and diabetes.
Collapse
Affiliation(s)
- Shiva Mansouri
- Diabetes Research Unit, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
23
|
Feng X, Wang W, Liu J, Liu Y. β-Arrestins: multifunctional signaling adaptors in type 2 diabetes. Mol Biol Rep 2010; 38:2517-28. [PMID: 21086182 DOI: 10.1007/s11033-010-0389-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 11/08/2010] [Indexed: 02/06/2023]
Abstract
β-arrestins are not only well-known negative regulators of G protein-coupled receptor (GPCR) signaling, but also important adaptors in modulating the strength and duration of cellular signaling by scaffolding and interacting with a lot of cytoplasmic proteins. While β-arrestins are rather well described signal-mediated molecules, they are not generally associated with insulin signaling. But recent work has confirmed the difference from original thought. The current review aims to explore the emerging roles for β-arrestins in regulating insulin action, inflammatory signal pathway and other cellular signaling which are associated with type 2 diabetes.
Collapse
Affiliation(s)
- Xiaotao Feng
- Institute of Chinese Integrative Medicine, Huashan Hospital, Fudan University, No.12 Wulumuqi Zhong Road, Shanghai, 200040, China
| | | | | | | |
Collapse
|
24
|
Horvath G, Reglodi D, Opper B, Brubel R, Tamas A, Kiss P, Toth G, Csernus V, Matkovits A, Racz B. Effects of PACAP on the oxidative stress-induced cell death in chicken pinealocytes is influenced by the phase of the circadian clock. Neurosci Lett 2010; 484:148-52. [DOI: 10.1016/j.neulet.2010.08.039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 08/09/2010] [Accepted: 08/12/2010] [Indexed: 01/31/2023]
|
25
|
Sakurai Y, Shintani N, Hayata A, Hashimoto H, Baba A. Trophic effects of PACAP on pancreatic islets: a mini-review. J Mol Neurosci 2010; 43:3-7. [PMID: 20645023 DOI: 10.1007/s12031-010-9424-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 07/01/2010] [Indexed: 01/05/2023]
Abstract
Progressive beta-cell insufficiency in the pancreas is a hallmark of both types I and II diabetes, and agents that protect against beta-cell dysfunction are potential drug targets for diabetes mellitus. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a strong secretagogue of insulin from pancreatic islets and is suggested to be involved in physiological blood glucose homeostasis and the pathology of diabetes. Recent studies in genetically engineered animal models have shown that PACAP stimulates pancreatic functions, especially in cooperation with other regulatory factors including glucose. Furthermore, chronic activation of PACAP signaling regulates pancreatic islet mass in a context-dependent manner. Accumulating in vivo and in vitro evidence suggest that PACAP has trophic effects and regulates both proliferation and cell viability of beta-cells and thereby contributes to protection against diabetes. This review focuses on such trophic actions of PACAP on pancreatic beta-cells and discusses the pathophysiological significance of pancreatic PACAP, with the aim to provide information for future development of treatment for diabetes.
Collapse
Affiliation(s)
- Yusuke Sakurai
- Department of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | | | | | | | | |
Collapse
|