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Puginier E, Leal-Fischer K, Gaitan J, Lallouet M, Scotti PA, Raoux M, Lang J. Extracellular electrophysiology on clonal human β-cell spheroids. Front Endocrinol (Lausanne) 2024; 15:1402880. [PMID: 38883608 PMCID: PMC11176477 DOI: 10.3389/fendo.2024.1402880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/06/2024] [Indexed: 06/18/2024] Open
Abstract
Background Pancreatic islets are important in nutrient homeostasis and improved cellular models of clonal origin may very useful especially in view of relatively scarce primary material. Close 3D contact and coupling between β-cells are a hallmark of physiological function improving signal/noise ratios. Extracellular electrophysiology using micro-electrode arrays (MEA) is technically far more accessible than single cell patch clamp, enables dynamic monitoring of electrical activity in 3D organoids and recorded multicellular slow potentials (SP) provide unbiased insight in cell-cell coupling. Objective We have therefore asked whether 3D spheroids enhance clonal β-cell function such as electrical activity and hormone secretion using human EndoC-βH1, EndoC-βH5 and rodent INS-1 832/13 cells. Methods Spheroids were formed either by hanging drop or proprietary devices. Extracellular electrophysiology was conducted using multi-electrode arrays with appropriate signal extraction and hormone secretion measured by ELISA. Results EndoC-βH1 spheroids exhibited increased signals in terms of SP frequency and especially amplitude as compared to monolayers and even single cell action potentials (AP) were quantifiable. Enhanced electrical signature in spheroids was accompanied by an increase in the glucose stimulated insulin secretion index. EndoC-βH5 monolayers and spheroids gave electrophysiological profiles similar to EndoC-βH1, except for a higher electrical activity at 3 mM glucose, and exhibited moreover a biphasic profile. Again, physiological concentrations of GLP-1 increased AP frequency. Spheroids also exhibited a higher secretion index. INS-1 cells did not form stable spheroids, but overexpression of connexin 36, required for cell-cell coupling, increased glucose responsiveness, dampened basal activity and consequently augmented the stimulation index. Conclusion In conclusion, spheroid formation enhances physiological function of the human clonal β-cell lines and these models may provide surrogates for primary islets in extracellular electrophysiology.
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Affiliation(s)
- Emilie Puginier
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Karen Leal-Fischer
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Julien Gaitan
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Marie Lallouet
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Pier-Arnaldo Scotti
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Matthieu Raoux
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Jochen Lang
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
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2
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Ray GW, Zeng Q, Kusi P, Zhang H, Shao T, Yang T, Wei Y, Li M, Che X, Guo R. Genetic and inflammatory factors underlying gestational diabetes mellitus: a review. Front Endocrinol (Lausanne) 2024; 15:1399694. [PMID: 38694942 PMCID: PMC11061502 DOI: 10.3389/fendo.2024.1399694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 03/28/2024] [Indexed: 05/04/2024] Open
Abstract
Gestational diabetes mellitus (GDM) poses a significant global health concern, impacting both maternal and fetal well-being. Early detection and treatment are imperative to mitigate adverse outcomes during pregnancy. This review delves into the pivotal role of insulin function and the influence of genetic variants, including SLC30A8, CDKAL1, TCF7L2, IRS1, and GCK, in GDM development. These genetic variations affect beta-cell function and insulin activity in crucial tissues, such as muscle, disrupting glucose regulation during pregnancy. We propose a hypothesis that this variation may disrupt zinc transport, consequently impairing insulin production and secretion, thereby contributing to GDM onset. Furthermore, we discussed the involvement of inflammatory pathways, such as TNF-alpha and IL-6, in predisposing individuals to GDM. Genetic modulation of these pathways may exacerbate glucose metabolism dysregulation observed in GDM patients. We also discussed how GDM affects cardiovascular disease (CVD) through a direct correlation between pregnancy and cardiometabolic function, increasing atherosclerosis, decreased vascular function, dyslipidemia, and hypertension in women with GDM history. However, further research is imperative to unravel the intricate interplay between inflammatory pathways, genetics, and GDM. This understanding is pivotal for devising targeted gene therapies and pharmacological interventions to rectify genetic variations in SLC30A8, CDKAL1, TCF7L2, IRS1, GCK, and other pertinent genes. Ultimately, this review offers insights into the pathophysiological mechanisms of GDM, providing a foundation for developing strategies to mitigate its impact.
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Affiliation(s)
- Gyan Watson Ray
- Department of Internal Medicine, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
- Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China
- Matenal and Child Research Institute, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
| | - Qiaoli Zeng
- Department of Internal Medicine, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
- Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China
- Matenal and Child Research Institute, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
| | - Phidelia Kusi
- University of Ghana, Ministry of Fisheries and Aquaculture Development, Fisheries Commission, Accra, Ghana
| | - Hengli Zhang
- Department of Internal Medicine, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
- Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China
- Matenal and Child Research Institute, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
| | - Taotao Shao
- Department of Internal Medicine, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
- Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China
| | - Taili Yang
- Matenal and Child Research Institute, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
| | - Yue Wei
- Matenal and Child Research Institute, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
| | - Mianqin Li
- Department of Obstetric, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, Guangdong, China
| | - Xiaoqun Che
- Department of Obstetric, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, Guangdong, China
- Reproductive Medicine Center, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, Guangdong, China
| | - Runmin Guo
- Department of Internal Medicine, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
- Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China
- Matenal and Child Research Institute, Shunde Women and Children’s Hospital (Maternity and Child Healthcare Hospital of Shunde Foshan), Guangdong Medical University, Foshan, China
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3
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Chen B, Yu P, Chan WN, Xie F, Zhang Y, Liang L, Leung KT, Lo KW, Yu J, Tse GMK, Kang W, To KF. Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets. Signal Transduct Target Ther 2024; 9:6. [PMID: 38169461 PMCID: PMC10761908 DOI: 10.1038/s41392-023-01679-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 09/15/2023] [Accepted: 10/10/2023] [Indexed: 01/05/2024] Open
Abstract
Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.
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Affiliation(s)
- Bonan Chen
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Peiyao Yu
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangdong Province Key Laboratory of Molecular Tumor Pathology, Guangzhou, China
| | - Wai Nok Chan
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Fuda Xie
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Yigan Zhang
- Institute of Biomedical Research, Taihe Hospital, Hubei University of Medicine, Shiyan, China
| | - Li Liang
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangdong Province Key Laboratory of Molecular Tumor Pathology, Guangzhou, China
| | - Kam Tong Leung
- Department of Pediatrics, The Chinese University of Hong Kong, Hong Kong, China
| | - Kwok Wai Lo
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Jun Yu
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Gary M K Tse
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Wei Kang
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China.
- CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
| | - Ka Fai To
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
- State Key Laboratory of Digestive Disease, Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China.
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Nguyen LTD, Gunathilake M, Lee J, Oh JH, Chang HJ, Sohn DK, Shin A, Kim J. Zinc intake, SLC30A8 rs3802177 polymorphism, and colorectal cancer risk in a Korean population: a case-control study. J Cancer Res Clin Oncol 2023; 149:16429-16440. [PMID: 37707576 DOI: 10.1007/s00432-023-05381-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/30/2023] [Indexed: 09/15/2023]
Abstract
PURPOSE Zinc is an essential micronutrient involving in multiple enzymatic reactions of human metabolism and biological functions affecting the cancer development. However, the relationship between dietary zinc intake and colorectal cancer (CRC) risk has been unclear. Herein, our study investigated the relationship between dietary zinc intake and CRC risk, and examined how the SLC30A8 rs3802177 genetic variant affects this association. METHODS A total of 1431 CRC cases and 2704 controls were selected to investigate the relationship between dietary zinc intake and CRC risk. After excluding individuals without genotype data, 1097 CRC cases and 1559 controls were used to evaluate the interaction between dietary zinc intake and the rs3802177 polymorphism in CRC risk. The odds ratios (ORs) and 95% confidence intervals (CIs) were measured using unconditional logistic regression models. RESULTS Higher dietary zinc intake was inversely associated with the risk of CRC in the total population [adjusted OR (aOR) = 0.80, 95% CI 0.66-0.96, p for trend = 0.018]. In the codominant model, G+ carriers of the SLC30A8 rs3802177 with higher consumption of zinc were observed to have a significantly lower risk of CRC in all participants (p for interaction = 0.020). In females, GG carriers with higher zinc intake showed a stronger protective effect against the development of CRC (p for interaction = 0.008). CONCLUSIONS In summary, our findings suggest an inverse association between dietary zinc intake and CRC risk, and this relationship may be modified by SLC30A8 rs3802177 polymorphism.
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Affiliation(s)
- Linh Thi Dieu Nguyen
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, 323 Ilsan-Ro, Ilsandong-Gu, Goyang-Si, Gyeonggi-Do, 10408, Republic of Korea
| | - Madhawa Gunathilake
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, 323 Ilsan-Ro, Ilsandong-Gu, Goyang-Si, Gyeonggi-Do, 10408, Republic of Korea
| | - Jeonghee Lee
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, 323 Ilsan-Ro, Ilsandong-Gu, Goyang-Si, Gyeonggi-Do, 10408, Republic of Korea
| | - Jae Hwan Oh
- Center for Colorectal Cancer, National Cancer Center Hospital, National Cancer Center, Goyang-Si, Gyeonggi-Do, South Korea
| | - Hee Jin Chang
- Center for Colorectal Cancer, National Cancer Center Hospital, National Cancer Center, Goyang-Si, Gyeonggi-Do, South Korea
| | - Dae Kyung Sohn
- Center for Colorectal Cancer, National Cancer Center Hospital, National Cancer Center, Goyang-Si, Gyeonggi-Do, South Korea
| | - Aesun Shin
- Department of Preventive Medicine, Seoul National University College of Medicine, Jongno-Gu, Seoul, South Korea
| | - Jeongseon Kim
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, 323 Ilsan-Ro, Ilsandong-Gu, Goyang-Si, Gyeonggi-Do, 10408, Republic of Korea.
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5
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Asadi F, Dhanvantari S. Pathways of Glucagon Secretion and Trafficking in the Pancreatic Alpha Cell: Novel Pathways, Proteins, and Targets for Hyperglucagonemia. Front Endocrinol (Lausanne) 2021; 12:726368. [PMID: 34659118 PMCID: PMC8511682 DOI: 10.3389/fendo.2021.726368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/13/2021] [Indexed: 12/15/2022] Open
Abstract
Patients with diabetes mellitus exhibit hyperglucagonemia, or excess glucagon secretion, which may be the underlying cause of the hyperglycemia of diabetes. Defective alpha cell secretory responses to glucose and paracrine effectors in both Type 1 and Type 2 diabetes may drive the development of hyperglucagonemia. Therefore, uncovering the mechanisms that regulate glucagon secretion from the pancreatic alpha cell is critical for developing improved treatments for diabetes. In this review, we focus on aspects of alpha cell biology for possible mechanisms for alpha cell dysfunction in diabetes: proglucagon processing, intrinsic and paracrine control of glucagon secretion, secretory granule dynamics, and alterations in intracellular trafficking. We explore possible clues gleaned from these studies in how inhibition of glucagon secretion can be targeted as a treatment for diabetes mellitus.
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Affiliation(s)
- Farzad Asadi
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
| | - Savita Dhanvantari
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
- Imaging Research Program, Lawson Health Research Institute, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
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6
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Xu J, Wijesekara N, Regeenes R, Rijjal DA, Piro AL, Song Y, Wu A, Bhattacharjee A, Liu Y, Marzban L, Rocheleau JV, Fraser PE, Dai FF, Hu C, Wheeler MB. Pancreatic β cell-selective zinc transporter 8 insufficiency accelerates diabetes associated with islet amyloidosis. JCI Insight 2021; 6:143037. [PMID: 34027899 PMCID: PMC8262350 DOI: 10.1172/jci.insight.143037] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 04/21/2021] [Indexed: 01/25/2023] Open
Abstract
GWAS have shown that the common R325W variant of SLC30A8 (ZnT8) increases the risk of type 2 diabetes (T2D). However, ZnT8 haploinsufficiency is protective against T2D in humans, counterintuitive to earlier work in humans and mouse models. Therefore, whether decreasing ZnT8 activity is beneficial or detrimental to β cell function, especially under conditions of metabolic stress, remains unknown. In order to examine whether the existence of human islet amyloid polypeptide (hIAPP), a coresident of the insulin granule, affects the role of ZnT8 in regulating β cell function, hIAPP-expressing transgenics were generated with reduced ZnT8 (ZnT8B+/– hIAPP) or null ZnT8 (ZnT8B–/– hIAPP) expression specifically in β cells. We showed that ZnT8B–/– hIAPP mice on a high-fat diet had intensified amyloid deposition and further impaired glucose tolerance and insulin secretion compared with control, ZnT8B–/–, and hIAPP mice. This can in part be attributed to impaired glucose sensing and islet cell synchronicity. Importantly, ZnT8B+/– hIAPP mice were also glucose intolerant and had reduced insulin secretion and increased amyloid aggregation compared with controls. These data suggest that loss of or reduced ZnT8 activity in β cells heightened the toxicity induced by hIAPP, leading to impaired β cell function and glucose homeostasis associated with metabolic stress.
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Affiliation(s)
- Jie Xu
- Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Key Clinical Center for Metabolic Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Nadeeja Wijesekara
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto Western Hospital, Toronto, Ontario Canada
| | - Romario Regeenes
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Dana Al Rijjal
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Anthony L Piro
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Youchen Song
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Anne Wu
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Alpana Bhattacharjee
- Division of Advanced Diagnostics, Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| | - Ying Liu
- Division of Advanced Diagnostics, Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| | - Lucy Marzban
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Jonathan V Rocheleau
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Paul E Fraser
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto Western Hospital, Toronto, Ontario Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Feihan F Dai
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Cheng Hu
- Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Key Clinical Center for Metabolic Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.,Institute for Metabolic Disease, Fengxian Central Hospital Affiliated to Southern Medical University, Shanghai, China
| | - Michael B Wheeler
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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7
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Sachse G, Haythorne E, Hill T, Proks P, Joynson R, Terrón-Expósito R, Bentley L, Tucker SJ, Cox RD, Ashcroft FM. The KCNJ11-E23K Gene Variant Hastens Diabetes Progression by Impairing Glucose-Induced Insulin Secretion. Diabetes 2021; 70:1145-1156. [PMID: 33568422 DOI: 10.2337/db20-0691] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 02/05/2021] [Indexed: 11/13/2022]
Abstract
The ATP-sensitive K+ (KATP) channel controls blood glucose levels by coupling glucose metabolism to insulin secretion in pancreatic β-cells. E23K, a common polymorphism in the pore-forming KATP channel subunit (KCNJ11) gene, has been linked to increased risk of type 2 diabetes. Understanding the risk-allele-specific pathogenesis has the potential to improve personalized diabetes treatment, but the underlying mechanism has remained elusive. Using a genetically engineered mouse model, we now show that the K23 variant impairs glucose-induced insulin secretion and increases diabetes risk when combined with a high-fat diet (HFD) and obesity. KATP-channels in β-cells with two K23 risk alleles (KK) showed decreased ATP inhibition, and the threshold for glucose-stimulated insulin secretion from KK islets was increased. Consequently, the insulin response to glucose and glycemic control was impaired in KK mice fed a standard diet. On an HFD, the effects of the KK genotype were exacerbated, accelerating diet-induced diabetes progression and causing β-cell failure. We conclude that the K23 variant increases diabetes risk by impairing insulin secretion at threshold glucose levels, thus accelerating loss of β-cell function in the early stages of diabetes progression.
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Affiliation(s)
- Gregor Sachse
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
| | - Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Thomas Hill
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Peter Proks
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
- Department of Physics, University of Oxford, Oxford, U.K
| | - Russell Joynson
- Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell Institute, Oxfordshire, U.K
| | - Raul Terrón-Expósito
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Liz Bentley
- Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell Institute, Oxfordshire, U.K
| | | | - Roger D Cox
- Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell Institute, Oxfordshire, U.K
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
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8
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Catapano MC, Parsons DS, Kotuniak R, Mladěnka P, Bal W, Maret W. Probing the Structure and Function of the Cytosolic Domain of the Human Zinc Transporter ZnT8 with Nickel(II) Ions. Int J Mol Sci 2021; 22:2940. [PMID: 33799326 PMCID: PMC8000985 DOI: 10.3390/ijms22062940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 11/30/2022] Open
Abstract
The human zinc transporter ZnT8 provides the granules of pancreatic β-cells with zinc (II) ions for assembly of insulin hexamers for storage. Until recently, the structure and function of human ZnTs have been modelled on the basis of the 3D structures of bacterial zinc exporters, which form homodimers with each monomer having six transmembrane α-helices harbouring the zinc transport site and a cytosolic domain with an α,β structure and additional zinc-binding sites. However, there are important differences in function as the bacterial proteins export an excess of zinc ions from the bacterial cytoplasm, whereas ZnT8 exports zinc ions into subcellular vesicles when there is no apparent excess of cytosolic zinc ions. Indeed, recent structural investigations of human ZnT8 show differences in metal binding in the cytosolic domain when compared to the bacterial proteins. Two common variants, one with tryptophan (W) and the other with arginine (R) at position 325, have generated considerable interest as the R-variant is associated with a higher risk of developing type 2 diabetes. Since the mutation is at the apex of the cytosolic domain facing towards the cytosol, it is not clear how it can affect zinc transport through the transmembrane domain. We expressed the cytosolic domain of both variants of human ZnT8 and have begun structural and functional studies. We found that (i) the metal binding of the human protein is different from that of the bacterial proteins, (ii) the human protein has a C-terminal extension with three cysteine residues that bind a zinc(II) ion, and (iii) there are small differences in stability between the two variants. In this investigation, we employed nickel(II) ions as a probe for the spectroscopically silent Zn(II) ions and utilised colorimetric and fluorimetric indicators for Ni(II) ions to investigate metal binding. We established Ni(II) coordination to the C-terminal cysteines and found differences in metal affinity and coordination in the two ZnT8 variants. These structural differences are thought to be critical for the functional differences regarding the diabetes risk. Further insight into the assembly of the metal centres in the cytosolic domain was gained from potentiometric investigations of zinc binding to synthetic peptides corresponding to N-terminal and C-terminal sequences of ZnT8 bearing the metal-coordinating ligands. Our work suggests the involvement of the C-terminal cysteines, which are part of the cytosolic domain, in a metal chelation and/or acquisition mechanism and, as now supported by the high-resolution structural work, provides the first example of metal-thiolate coordination chemistry in zinc transporters.
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Affiliation(s)
- Maria Carmen Catapano
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, Franklin-Wilkins Bldg, 150 Stamford St., London SE1 9NH, UK; (M.C.C.); (D.S.P.)
- Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic
| | - Douglas S. Parsons
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, Franklin-Wilkins Bldg, 150 Stamford St., London SE1 9NH, UK; (M.C.C.); (D.S.P.)
- Department of Radiology, Boston University School of Medicine, 670 Albany Street, Boston, MA 02118, USA
| | - Radosław Kotuniak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (R.K.); (W.B.)
| | - Přemysl Mladěnka
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic;
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (R.K.); (W.B.)
| | - Wolfgang Maret
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, Franklin-Wilkins Bldg, 150 Stamford St., London SE1 9NH, UK; (M.C.C.); (D.S.P.)
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9
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Barragán-Álvarez CP, Padilla-Camberos E, Díaz NF, Cota-Coronado A, Hernández-Jiménez C, Bravo-Reyna CC, Díaz-Martínez NE. Loss of Znt8 function in diabetes mellitus: risk or benefit? Mol Cell Biochem 2021; 476:2703-2718. [PMID: 33666829 DOI: 10.1007/s11010-021-04114-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
The zinc transporter 8 (ZnT8) plays an essential role in zinc homeostasis inside pancreatic β cells, its function is related to the stabilization of insulin hexameric form. Genome-wide association studies (GWAS) have established a positive and negative relationship of ZnT8 variants with type 2 diabetes mellitus (T2DM), exposing a dual and controversial role. The first hypotheses about its role in T2DM indicated a higher risk of developing T2DM for loss of function; nevertheless, recent GWAS of ZnT8 loss-of-function mutations in humans have shown protection against T2DM. With regard to the ZnT8 role in T2DM, most studies have focused on rodent models and common high-risk variants; however, considerable differences between human and rodent models have been found and the new approaches have included lower-frequency variants as a tool to clarify gene functions, allowing a better understanding of the disease and offering possible therapeutic targets. Therefore, this review will discuss the physiological effects of the ZnT8 variants associated with a major and lower risk of T2DM, emphasizing the low- and rare-frequency variants.
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Affiliation(s)
- Carla P Barragán-Álvarez
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Eduardo Padilla-Camberos
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Nestor F Díaz
- Departamento de Fisiología y Desarrollo Celular, Instituto Nacional de Perinatología, Mexico City, Mexico
| | - Agustín Cota-Coronado
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico
| | - Claudia Hernández-Jiménez
- Departamento de Cirugía Experimental, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Carlos C Bravo-Reyna
- Departamento de Cirugía Experimental, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Nestor E Díaz-Martínez
- Biotecnología Médica y Farmacéutica, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Guadalajara, Mexico.
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10
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Sala D, Giachetti A, Rosato A. Insights into the Dynamics of the Human Zinc Transporter ZnT8 by MD Simulations. J Chem Inf Model 2021; 61:901-912. [PMID: 33508935 PMCID: PMC8023586 DOI: 10.1021/acs.jcim.0c01139] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Indexed: 02/07/2023]
Abstract
ZnT8 is a human zinc(II) transporter expressed at the membrane of secretory granules where it contributes to insulin storage importing zinc ions from the cytosol. In the human population, the two most common ZnT8 variants carry an arginine (R325) or a tryptophan (W325) in position 325. The former variant has the most efficient kinetics in zinc transport and has been correlated to a higher risk of developing insulin resistance. On the contrary, the W325 variant is less active and protects against type-2-diabetes. Here, we used molecular dynamics (MD) simulations to investigate the main differences between the R325 and W325 variants in the interaction with zinc(II) ions. Our simulations suggested that the position of the metal ion within the transport site was not the same for the two variants, underlying a different rearrangement of the transmembrane (TM) helices in the channel. The W325 variant featured a peculiar zinc environment not detected in the experimental structures. With respect to conformational dynamics, we observed that the R325 variant was significantly more flexible than W325, with the main role played by the transmembrane domain (TMD) and the C-terminal domain (CTD). This dynamics affected the packing of the TM helices and thus the channel accessibility from the cytosol. The dimer interface that keeps the two TM channels in contact became looser in both variants upon zinc binding to the transport site, suggesting that this may be an important step toward the switch from the inward- to the outward-facing state of the protein.
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Affiliation(s)
- Davide Sala
- Magnetic
Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Andrea Giachetti
- Consorzio
Interuniversitario di Risonanze Magnetiche di Metallo Proteine, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Antonio Rosato
- Magnetic
Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department
of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
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11
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Sargazi S, Heidari Nia M, Sargazi FM, Sheervalilou R, Saravani R, Mirinejad S. SNPs in the 3'-untranslated region of SLC30A8 confer risk of type 2 diabetes mellitus in a south-east Iranian population: Evidences from case-control and bioinformatics studies. J Diabetes Metab Disord 2020; 19:979-988. [PMID: 33553018 PMCID: PMC7843856 DOI: 10.1007/s40200-020-00590-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/26/2020] [Accepted: 07/15/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) is a heterogenic disease with increasing incidence. The SLC30A8 gene encodes an islet zinc transporter (ZnT8), and its variants have been associated with glucose and pro-insulin levels. This study was aimed to examine the effects of a missense variant (rs13266634 C/T), and two 3'UTR variants (rs2466294 C/G and rs2466293 T/C) in SLC30A8 gene on T2DM risk in a south-east Iranian population. METHODS In this experiment, 450 patients diagnosed with T2DM and 453 healthy subjects from the same geographic area were enrolled. Genotypes were amplified using the ARMS-PCR method. In silico analyses were performed to determine the effects of the variants on the local structure of mRNA, splicing patterns, and potential miRNA-gene interactions as well. RESULTS Significant differences were noticed between cases and controls regarding the genotypic and allelic distribution of the studied variants. As regards rs2466293 and rs2466294 variants, enhanced risk of T2DM was found under allelic, dominant, recessive, and codominant models (OR > 1). Besides, different genetic models of rs13266634 were associated with decreased risk of T2DM (OR < 1). Bioinformatics analyses indicated that the rs2466293 variant might influence the binding of some miRNAs, while the G-allele of rs2466294 decreased the stability of SLC30A8-mRNA. CONCLUSIONS In our population, both SNPs in the 3'-untranslated region of SLC30A8 increased the risk of T2DM, while the rs13266634 variant showed a protective association against T2DM susceptibility. Investigating the effects of other variants in this gene or other ZnTs can further indicate such associations in subjects from the same ethnicity.
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Affiliation(s)
- Saman Sargazi
- Cellular and Molecular Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Milad Heidari Nia
- Cellular and Molecular Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Fariba Mirani Sargazi
- Cellular and Molecular Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Roghayeh Sheervalilou
- Cellular and Molecular Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Ramin Saravani
- Cellular and Molecular Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
- Department of Clinical Biochemistry, School of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Shekoufeh Mirinejad
- Cellular and Molecular Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
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12
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Huang Q, Du J, Merriman C, Gong Z. Genetic, Functional, and Immunological Study of ZnT8 in Diabetes. Int J Endocrinol 2019; 2019:1524905. [PMID: 30936916 PMCID: PMC6413397 DOI: 10.1155/2019/1524905] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/14/2018] [Accepted: 12/05/2018] [Indexed: 12/11/2022] Open
Abstract
Zinc level in the body is finely regulated to maintain cellular function. Dysregulation of zinc metabolism may induce a variety of diseases, e.g., diabetes. Zinc participates in insulin synthesis, storage, and secretion by functioning as a "cellular second messenger" in the insulin signaling pathway and glucose homeostasis. The highest zinc concentration is in the pancreas islets. Zinc accumulation in cell granules is manipulated by ZnT8, a zinc transporter expressed predominately in pancreatic α and β cells. A common ZnT8 gene (SLC30A8) polymorphism increases the risk of type 2 diabetes mellitus (T2DM), and rare mutations may present protective effects. In type 1 diabetes mellitus (T1DM), autoantibodies show specificity for binding two variants of ZnT8 (R or W at amino acid 325) dictated by a polymorphism in SLC30A8. In this review, we summarize the structure, feature, functions, and polymorphisms of ZnT8 along with its association with diabetes and explore future study directions.
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Affiliation(s)
- Qiong Huang
- Department of Pharmacy, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Jie Du
- Department of Pharmacy, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Chengfeng Merriman
- Department of Physiology, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Zhicheng Gong
- Department of Pharmacy, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
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13
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Abstract
Findings from the past 10 years have placed the glucagon-secreting pancreatic α-cell centre stage in the development of diabetes mellitus, a disease affecting almost one in every ten adults worldwide. Glucagon secretion is reduced in patients with type 1 diabetes mellitus, increasing the risk of insulin-induced hypoglycaemia, but is enhanced in type 2 diabetes mellitus, exacerbating the effects of diminished insulin release and action on blood levels of glucose. A better understanding of the mechanisms underlying these changes is therefore an important goal. RNA sequencing reveals that, despite their opposing roles in the control of blood levels of glucose, α-cells and β-cells have remarkably similar patterns of gene expression. This similarity might explain the fairly facile interconversion between these cells and the ability of the α-cell compartment to serve as a source of new β-cells in models of extreme β-cell loss that mimic type 1 diabetes mellitus. Emerging data suggest that GABA might facilitate this interconversion, whereas the amino acid glutamine serves as a liver-derived factor to promote α-cell replication and maintenance of α-cell mass. Here, we survey these developments and their therapeutic implications for patients with diabetes mellitus.
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Affiliation(s)
| | - Pauline Chabosseau
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK.
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14
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Jenkins A, Lengyel I, Rutter GA, Lowe N, Shai I, Tirosh A, Petro T, Khamaisi M, Andrews S, Zmora N, Gross A, Maret W, Lewis EC, Moran A. Obesity, diabetes and zinc: A workshop promoting knowledge and collaboration between the UK and Israel, november 28-30, 2016 - Israel. J Trace Elem Med Biol 2018; 49:79-85. [PMID: 29895375 DOI: 10.1016/j.jtemb.2018.04.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 04/18/2018] [Accepted: 04/18/2018] [Indexed: 01/23/2023]
Affiliation(s)
- Alicia Jenkins
- Centre for Experimental Medicine, Queens University, Belfast, UK; NHMRC Clinical Trials Centre, University of Sydney, Australia
| | - Imre Lengyel
- Centre for Experimental Medicine, Queens University, Belfast, UK.
| | - Guy A Rutter
- Faculty of Medicine, Department of Medicine, Imperial College, London, UK
| | - Nicola Lowe
- School of Sport and Wellbeing, University of Central Lancashire Preston, UK
| | - Iris Shai
- Department of Public Health School of Pharmacy, Ben Gurion University, Beer Sheva, Israel
| | - Amir Tirosh
- The Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
| | - Tunde Petro
- Centre for Public Health, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, UK
| | - Mogher Khamaisi
- Internal Medicine D and the Institute of Endocrinology, Diabetes and Metabolism, Rambam Medical Center and RB Rappaport Faculty of Medicine-Technion, Haifa, Israel
| | - Simon Andrews
- School of Biological Sciences, University of Reading, Reading, UK
| | - Niv Zmora
- Department of Immunology Weizmann Institute of Science Rehovot, Israel
| | - Atan Gross
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Wolfgang Maret
- Department of Biochemistry & Diabetes and Nutritional Sciences Division King's College London, UK
| | - Eli C Lewis
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Arie Moran
- Dept. of Physiology and Cell Biology, Ben Gurion University of the Negev, Beer Sheva, Israel
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15
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Parsons DS, Hogstrand C, Maret W. The C-terminal cytosolic domain of the human zinc transporter ZnT8 and its diabetes risk variant. FEBS J 2018; 285:1237-1250. [PMID: 29430817 PMCID: PMC5947572 DOI: 10.1111/febs.14402] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/22/2017] [Accepted: 02/05/2018] [Indexed: 12/21/2022]
Abstract
A significant aspect of the control of cellular zinc in eukarya is its subcellular re‐distribution. One of the four human vesicular zinc transporters, ZnT8, supplies the millimolar zinc concentrations of insulin granules in pancreatic β‐cells, affecting insulin processing, crystallisation and secretion. ZnT8 has a transmembrane and a C‐terminal cytosolic domain; the latter has important functions and purportedly mediates protein–protein interactions, senses cytosolic zinc and/or channels zinc to the transport site in the transmembrane domain (TMD). A common variant W325R in the C‐terminal domain (CTD) increases the risk to develop type 2 diabetes and affects autoantibody specificity in type 1 diabetes. To investigate the differences between the two protein variants, we purified and biophysically characterised both variants of the ZnT8 CTD [R325 variant of ZnT8 CTD (aa267–369) (ZnT8cR) and W325 variant of ZnT8 CTD (aa267–369) (ZnT8cW)]. The domains fold independently of the TMD. Remarkably, the ZnT8cW variant (diabetes protection in the full‐length protein) is less thermostable than the ZnT8cR variant (diabetes risk in the full‐length protein). The ZnT8cW monomers associate with higher affinity. Both CTD variants bind zinc with a stoichiometry that differs from bacterial homologues, emphasising the limitation of the latter as models for the structure and function of the human proteins. The relatively small but reproducible differences between the two ZnT8 CTD variants begin to provide a molecular basis for the different diabetes susceptibility caused by the full‐length ZnT8 proteins.
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Affiliation(s)
- Douglas S Parsons
- Metal Metabolism Group, Departments of Biochemistry and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, UK
| | - Christer Hogstrand
- Metal Metabolism Group, Departments of Biochemistry and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, UK
| | - Wolfgang Maret
- Metal Metabolism Group, Departments of Biochemistry and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, UK
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16
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Olgar Y, Durak A, Tuncay E, Bitirim CV, Ozcinar E, Inan MB, Tokcaer-Keskin Z, Akcali KC, Akar AR, Turan B. Increased free Zn 2+ correlates induction of sarco(endo)plasmic reticulum stress via altered expression levels of Zn 2+ -transporters in heart failure. J Cell Mol Med 2018; 22:1944-1956. [PMID: 29333637 PMCID: PMC5824399 DOI: 10.1111/jcmm.13480] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 10/29/2017] [Indexed: 12/14/2022] Open
Abstract
Zn2+ -homoeostasis including free Zn2+ ([Zn2+ ]i ) is regulated through Zn2+ -transporters and their comprehensive understanding may be important due to their contributions to cardiac dysfunction. Herein, we aimed to examine a possible role of Zn2+ -transporters in the development of heart failure (HF) via induction of ER stress. We first showed localizations of ZIP8, ZIP14 and ZnT8 to both sarcolemma and S(E)R in ventricular cardiomyocytes (H9c2 cells) using confocal together with calculated Pearson's coefficients. The expressions of ZIP14 and ZnT8 were significantly increased with decreased ZIP8 level in HF. Moreover, [Zn2+ ]i was significantly high in doxorubicin-treated H9c2 cells compared to their controls. We found elevated levels of ER stress markers, GRP78 and CHOP/Gadd153, confirming the existence of ER stress. Furthermore, we measured markedly increased total PKC and PKCα expression and PKCα-phosphorylation in HF. A PKC inhibition induced significant decrease in expressions of these ER stress markers compared to controls. Interestingly, direct increase in [Zn2+ ]i using zinc-ionophore induced significant increase in these markers. On the other hand, when we induced ER stress directly with tunicamycin, we could not observe any effect on expression levels of these Zn2+ transporters. Additionally, increased [Zn2+ ]i could induce marked activation of PKCα. Moreover, we observed marked decrease in [Zn2+ ]i under PKC inhibition in H9c2 cells. Overall, our present data suggest possible role of Zn2+ transporters on an intersection pathway with increased [Zn2+ ]i and PKCα activation and induction of HF, most probably via development of ER stress. Therefore, our present data provide novel information how a well-controlled [Zn2+ ]i via Zn2+ transporters and PKCα can be important therapeutic approach in prevention/treatment of HF.
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Affiliation(s)
- Yusuf Olgar
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Aysegul Durak
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Erkan Tuncay
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | | | - Evren Ozcinar
- Department of Cardiovascular Surgery, Heart Center, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Mustafa Bahadir Inan
- Department of Cardiovascular Surgery, Heart Center, Ankara University Faculty of Medicine, Ankara, Turkey
| | | | - Kamil Can Akcali
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Ahmet Ruchan Akar
- Department of Cardiovascular Surgery, Heart Center, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
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17
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Giacconi R, Cai L, Costarelli L, Cardelli M, Malavolta M, Piacenza F, Provinciali M. Implications of impaired zinc homeostasis in diabetic cardiomyopathy and nephropathy. Biofactors 2017; 43:770-784. [PMID: 28845600 DOI: 10.1002/biof.1386] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/12/2017] [Accepted: 07/27/2017] [Indexed: 12/18/2022]
Abstract
Impaired zinc homeostasis is observed in diabetes mellitus (DM2) and its complications. Zinc has a specific role in pancreatic β-cells via insulin synthesis, storage, and secretion. Intracellular zinc homeostasis is tightly controlled by zinc transporters (ZnT and Zip families) and metallothioneins (MT) which modulate the uptake, storage, and distribution of zinc. Several investigations in animal models demonstrate the protective role of MT in DM2 and its cardiovascular or renal complications, while a copious literature shows that a common polymorphism (R325W) in ZnT8, which affects the protein's zinc transport activity, is associated with increased DM2 risk. Emerging studies highlight a role of other zinc transporters in β-cell function, suggesting that targeting them could make a possible contribution in managing the hyperglycemia in diabetic patients. This article summarizes the current findings concerning the role of zinc homeostasis in DM2 pathogenesis and development of diabetic cardiomyopathy and nephropathy and suggests novel therapeutic targets. © 2017 BioFactors, 43(6):770-784, 2017.
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Affiliation(s)
- Robertina Giacconi
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Lu Cai
- Pediatric Research Institute at the Department of Pediatrics, Wendy L. Novak Diabetes Care Center, University of Louisville, Louisville, KY, USA
| | - Laura Costarelli
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Maurizio Cardelli
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Marco Malavolta
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Francesco Piacenza
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Mauro Provinciali
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
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18
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Induction of endoplasmic reticulum stress and changes in expression levels of Zn 2+-transporters in hypertrophic rat heart. Mol Cell Biochem 2017; 440:209-219. [PMID: 28849306 DOI: 10.1007/s11010-017-3168-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 08/16/2017] [Indexed: 12/15/2022]
Abstract
Clinical and experimental studies have shown an association between intracellular free Zn2+ ([Zn2+]i)-dyshomeostasis and cardiac dysfunction besides [Ca2+]i-dyshomeostasis. Since [Zn2+]i-homeostasis is regulated through Zn2+-transporters depending on their subcellular distributions, one can hypothesize that any imbalance in Zn2+-homeostasis via alteration in Zn2+-transporters may be associated with the induction of ER stress and apoptosis in hypertrophic heart. We used a transverse aortic constriction (TAC) model to induce hypertrophy in young male rat heart. We confirmed the development of hypertrophy with a high ratio of heart to body weight and cardiomyocyte capacitance. The expression levels of ER stress markers GRP78, CHOP/Gadd153, and calnexin are significantly high in TAC-group in comparison to those of controls (SHAM-group). Additionally, we detected high expression levels of apoptotic status marker proteins such as the serine kinase GSK-3β, Bax-to-Bcl-2 ratio, and PUMA in TAC-group in comparison to SHAM-group. The ratios of phospho-Akt to Akt and phospho-NFκB to the NFκB are significantly higher in TAC-group than in SHAM-group. Furthermore, we observed markedly increased phospho-PKCα and PKCα levels in TAC-group. We, also for the first time, determined significantly increased ZIP7, ZIP14, and ZnT8 expressions along with decreased ZIP8 and ZnT7 levels in the heart tissue from TAC-group in comparison to SHAM-group. Furthermore, a roughly calculated total expression level of ZIPs responsible for Zn2+-influx into the cytosol (increased about twofold) can be also responsible for the markedly increased [Zn2+]i detected in hypertrophic cardiomyocytes. Taking into consideration the role of increased [Zn2+]i via decreased ER-[Zn2+] in the induction of ER stress in cardiomyocytes, our present data suggest that differential changes in the expression levels of Zn2+-transporters can underlie mechanical dysfunction, in part due to the induction of ER stress and apoptosis in hypertrophic heart via increased [Zn2+]i- besides [Ca2+]i-dyshomeostasis.
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19
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da Silva Xavier G, Mondragon A, Mourougavelou V, Cruciani-Guglielmacci C, Denom J, Herrera PL, Magnan C, Rutter GA. Pancreatic alpha cell-selective deletion of Tcf7l2 impairs glucagon secretion and counter-regulatory responses to hypoglycaemia in mice. Diabetologia 2017; 60:1043-1050. [PMID: 28343277 PMCID: PMC5423960 DOI: 10.1007/s00125-017-4242-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 02/15/2017] [Indexed: 01/19/2023]
Abstract
AIMS/HYPOTHESIS Transcription factor 7-like 2 (TCF7L2) is a high mobility group (HMG) box-containing transcription factor and downstream effector of the Wnt signalling pathway. SNPs in the TCF7L2 gene have previously been associated with an increased risk of type 2 diabetes in genome-wide association studies. In animal studies, loss of Tcf7l2 function is associated with defective islet beta cell function and survival. Here, we explore the role of TCF7L2 in the control of the counter-regulatory response to hypoglycaemia by generating mice with selective deletion of the Tcf7l2 gene in pancreatic alpha cells. METHODS Alpha cell-selective deletion of Tcf7l2 was achieved by crossing mice with floxed Tcf7l2 alleles to mice bearing a Cre recombinase transgene driven by the preproglucagon promoter (PPGCre), resulting in Tcf7l2AKO mice. Glucose homeostasis and hormone secretion in vivo and in vitro, and islet cell mass were measured using standard techniques. RESULTS While glucose tolerance was unaffected in Tcf7l2AKO mice, glucose infusion rates were increased (AUC for glucose during the first 60 min period of hyperinsulinaemic-hypoglycaemic clamp test was increased by 1.98 ± 0.26-fold [p < 0.05; n = 6] in Tcf7l2AKO mice vs wild-type mice) and glucagon secretion tended to be lower (plasma glucagon: 0.40 ± 0.03-fold vs wild-type littermate controls [p < 0.01; n = 6]). Tcf7l2AKO mice displayed reduced fasted plasma glucose concentration. Glucagon release at low glucose was impaired in islets isolated from Tcf7l2AKO mice (0.37 ± 0.02-fold vs islets from wild-type littermate control mice [p < 0.01; n = 6). Alpha cell mass was also reduced (72.3 ± 20.3% [p < 0.05; n = 7) in Tcf7l2AKO mice compared with wild-type mice. CONCLUSIONS/INTERPRETATION The present findings demonstrate an alpha cell-autonomous role for Tcf7l2 in the control of pancreatic glucagon secretion and the maintenance of alpha cell mass and function.
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Affiliation(s)
- Gabriela da Silva Xavier
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, W12 0NN, UK.
| | - Angeles Mondragon
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, W12 0NN, UK
| | - Vishnou Mourougavelou
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, W12 0NN, UK
| | | | - Jessica Denom
- Université Paris Diderot Paris 7 - CNRS UMR 8251, Paris, France
| | - Pedro Luis Herrera
- Department of Genetic Medicine & Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | | | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, W12 0NN, UK
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Zhang M, Zhou Z, Wang J, Li S. ZnT8107-115/HLA-A2 dimers attenuate the severity of diabetes by inducing CD8+ T cell tolerance. Immunol Lett 2016; 180:66-72. [DOI: 10.1016/j.imlet.2016.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 10/15/2016] [Accepted: 11/06/2016] [Indexed: 12/16/2022]
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