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Dong Z, Wang J, Qiu T, Wu J, An Y, Shi X, Sun X, Jiang L, Liu X, Yang G, Cao J, Yao X. Perfluorooctane sulfonate induces mitochondrial calcium overload and early hepatic insulin resistance via autophagy/detyrosinated alpha-tubulin-regulated IP3R2-VDAC1-MICU1 interaction. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 825:153933. [PMID: 35192817 DOI: 10.1016/j.scitotenv.2022.153933] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 06/14/2023]
Abstract
Perfluorooctane sulfonate (PFOS), one kind of persistent organic pollutants, is associated with insulin resistance (IR) in general population. However, the exact mechanism is still obscure. In this study, we found that 50 μM PFOS caused IR in L-02 hepatocytes after 1 h, and induced autophagy and mitochondrial calcium (Ca2+) accumulation as early as 0.5 h. Inhibiting autophagy relieved mitochondrial Ca2+ overload and then reversed IR. Mitochondria were aggregated at cell periphery, and extracellular Ca2+ from IP3R2 on the plasma membrane, rather than endoplasmic reticulum Ca2+, was the priority source of mitochondrial Ca2+ uptake at early stages of PFOS exposure. Furthermore, we discovered that the linkage connecting autophagy and mitochondrial Ca2+ response was detyrosinated α-tubulin, which autophagy-dependently ascended, interacted with VDAC1 and enhanced the formation of IP3R2-VDAC1-MICU1 complex. Consistently, PFOS caused IR, activated autophagy, induced mitochondrial Ca2+ overload, increased the level of detyrosinated α-tubulin, and promoted the formation of IP3R2-VDAC1-MICU1 complex in the liver of C57BL/6J mice exposed to 2.5 mg/kg/day PFOS for 6 weeks. This study clarified that autophagy and mitochondrial Ca2+ accumulation were the early and triggering event that caused PFOS-related IR, also unveiled a novel mechanism regulating mitochondrial Ca2+ homeostasis.
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Affiliation(s)
- Zhanchen Dong
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Jianyu Wang
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Tianming Qiu
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Jialu Wu
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Yu An
- Dalian Municipal Center for Disease Control and Prevention, 151 Yueling West Street, Ganjingzi District, Dalian 116037, PR China
| | - Xiaoxia Shi
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Xiance Sun
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Liping Jiang
- Department of Food Nutrition and Safety, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Xiaofang Liu
- Department of Food Nutrition and Safety, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Guang Yang
- Department of Food Nutrition and Safety, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Jun Cao
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Xiaofeng Yao
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China.
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2
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Uryash A, Mijares A, Lopez CE, Adams JA, Lopez JR. Chronic Elevation of Skeletal Muscle [Ca 2+] i Impairs Glucose Uptake. An in Vivo and in Vitro Study. Front Physiol 2022; 13:872624. [PMID: 35547584 PMCID: PMC9083325 DOI: 10.3389/fphys.2022.872624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/04/2022] [Indexed: 12/17/2022] Open
Abstract
Skeletal muscle is the primary site of insulin-mediated glucose uptake through the body and, therefore, an essential contributor to glucose homeostasis maintenance. We have recently provided evidence that chronic elevated intracellular Ca2+ concentration at rest [(Ca2+)i] compromises glucose homeostasis in malignant hyperthermia muscle cells. To further investigate how chronic elevated muscle [Ca2+]i modifies insulin-mediated glucose homeostasis, we measured [Ca2+]i and glucose uptake in vivo and in vitro in intact polarized muscle cells from glucose-intolerant RYR1-p.R163C and db/db mice. Glucose-intolerant RYR1-p.R163C and db/db mice have significantly elevated muscle [Ca2+]i and reduced muscle glucose uptake compared to WT muscle cells. Dantrolene treatment (1.5 mg/kg IP injection for 2 weeks) caused a significant reduction in fasting blood glucose levels and muscle [Ca2+]i and increased muscle glucose uptake compared to untreated RYR1-p.R163C and db/db mice. Furthermore, RYR1-p.R163C and db/db mice had abnormal basal insulin levels and response to glucose-stimulated insulin secretion. In vitro experiments conducted on single muscle fibers, dantrolene improved insulin-mediated glucose uptake in RYR1-p.R163C and db/db muscle fibers without affecting WT muscle fibers. In muscle cells with chronic elevated [Ca2+]i, GLUT4 expression was significantly lower, and the subcellular fraction (plasma membrane/cytoplasmic) was abnormal compared to WT. The results of this study suggest that i) Chronic elevated muscle [Ca2+]i decreases insulin-stimulated glucose uptake and consequently causes hyperglycemia; ii) Reduced muscle [Ca2+]i by dantrolene improves muscle glucose uptake and subsequent hyperglycemia; iii) The mechanism by which chronic high levels of [Ca2+]i interfere with insulin action appears to involve the expression of GLUT4 and its subcellular fractionation.
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Affiliation(s)
- Arkady Uryash
- Division of Neonatology, Mount Sinai Medical Center, Miami Beach, FL, United States
| | - Alfredo Mijares
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Carlos E Lopez
- Department of Physiotherapy, Wellmax Medical Center, Miami, FL, United States
| | - Jose A Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami Beach, FL, United States
| | - Jose R Lopez
- Department of Research, Mount Sinai Medical Center, Miami Beach, FL, United States
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3
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Ranđelović S, Bipat R. A Review of Coumarins and Coumarin-Related Compounds for Their Potential Antidiabetic Effect. Clin Med Insights Endocrinol Diabetes 2022; 14:11795514211042023. [PMID: 35173509 PMCID: PMC8842344 DOI: 10.1177/11795514211042023] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 08/05/2021] [Indexed: 12/21/2022] Open
Abstract
Background and aims: Worldwide, type 2 diabetes mellitus accounts for a considerable burden of disease, with an estimated global cost of >800 billion USD annually. For this reason, the search for more effective and efficient therapeutic anti-diabetic agents is continuing. Coumarins are naturally derived and synthetic molecules with a wide variety of biological actions. The most common application of these molecules in medicine is for their thrombostatic activity. This study aims to give an overview of the current knowledge about the applicability of these chemical products in the therapeutic strategy against diabetes and its complications. Methods: For this purpose, we searched internet databases for publications and abstracts in English that investigated the effects of coumarins or coumarin-like agents with potential anti-diabetic activity. Results: The result is that a variety of these agents have proven in in vitro, in silico, and simple animal models to possess properties that may reduce the glucose absorption rate in the intestines, increase the level of insulin, increase the cellular uptake of glucose or reduce the gluconeogenesis. In addition, some of these agents also reduced the level of glycation of peptides in diabetic animal models and showed antioxidant properties. Conclusion: In conclusion, we can summarize that coumarins and their related derivatives may be potential antidiabetic agents. Useful formulations with appropriate pharmacokinetic and pharmacodynamic properties must be developed and tested for their efficacy and toxicity in comprehensive animal models before they can enter clinical trials.
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Affiliation(s)
- Sara Ranđelović
- Department of Chemistry, Faculty of Sciences and Mathematics, University of Niš, Niš, Serbia
| | - Robbert Bipat
- Department of Physiology, Faculty of Medical Science, Anton de Kom University of Suriname, Paramaribo, Suriname
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Das S, Choudhuri D. Role of dietary calcium and its possible mechanism against metabolic disorders: A concise review. J Food Biochem 2021; 45:e13697. [PMID: 33694258 DOI: 10.1111/jfbc.13697] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 01/19/2021] [Accepted: 02/22/2021] [Indexed: 12/21/2022]
Abstract
The global prevalence of metabolic disorders including hypertension, dyslipidemia, insulin resistance, nonalcoholic fatty liver, and cardiovascular diseases seemed to affect people of all ages cutting across the national, economic, and demographic barrier. Therefore, the prevention of metabolic disorders is considered of paramount importance. The dietary role of nutrients including vitamins and minerals is one of the recommended preventive measures against metabolic disorders in modern society. Recently, dietary calcium, a common nutrient not only showed a beneficial effect against obesity through weight management, but also gained great attention against the risk of metabolic disorders. Though dietary calcium shows several beneficial effects against metabolic disorders but some inconsistent results were also reported. So, the present review aims to extract recent knowledge as well as their possible underlying mechanisms regarding the role of dietary calcium against metabolic disorders. The present review also discusses the negative impact as well as prospect of calcium intake on health issues. In summary, high calcium diet prevents the harmful consequences of metabolic disorders by regulating hormonal actions, alteration in intracellular calcium level, renin-angiotensin system, intestinal fat absorption, fecal fat excretion, lipid metabolism, carbohydrate metabolism, inflammation, and oxidative stress which together improve the metabolic health of an individual. PRACTICAL APPLICATIONS: Metabolic disorder is a global health issue across all sections of society and is growing rapidly in spite of several attempts by the scientific community to prevent it. Recently dietary calcium gained great attention in the last few years for its role in the management and treatment of metabolic disorders. The current review highlights the beneficial role of dietary calcium against several metabolic complications by exploring their underlying mechanisms at cellular level. This study will provide valuable information regarding the recommendation of dietary calcium in health policy as well as its inclusion in the dietary chart through calcium-rich foods and/or taking calcium supplements which can be a useful approach in preventing the risk of metabolic disorder depending on the health status of an individual.
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Affiliation(s)
- Sandeep Das
- Reproductive Physiology and Endocrinology Laboratory, Department of Human Physiology, Tripura University (A Central University), Agartala, India
| | - Dipayan Choudhuri
- Reproductive Physiology and Endocrinology Laboratory, Department of Human Physiology, Tripura University (A Central University), Agartala, India
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Akter S, Eguchi M, Kochi T, Kabe I, Nanri A, Mizoue T. Association of Serum Calcium and Phosphate Concentrations with Glucose Metabolism Markers: The Furukawa Nutrition and Health Study. Nutrients 2020; 12:nu12082344. [PMID: 32764504 PMCID: PMC7468836 DOI: 10.3390/nu12082344] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 08/03/2020] [Indexed: 01/03/2023] Open
Abstract
Calcium and phosphate may play an important role in cardio-metabolic abnormalities, including type 2 diabetes; however, epidemiological evidence of the association of calcium and phosphate status with glucose metabolism among Asians is limited. In the current study, we performed a cross-sectional analysis of the association of serum calcium, phosphate, and calcium–phosphate product concentrations with glucose metabolism markers among Japanese individuals. Overall, 1701 workers (aged 18–78 years) who participated in a health survey were enrolled in this study. Multivariable linear regression models were used to estimate means of homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β), and glycated hemoglobin (HbA1c). Serum calcium concentration was positively associated with HOMA-IR and HbA1c (p for trend < 0.01). Multivariable-adjusted means (95% confidence interval (CI)) of HOMA-IR for the lowest and highest quartiles of serum calcium were 0.78 (0.75–0.82) and 1.01 (0.96–1.07), respectively. The corresponding values for HbA1c were 5.24 (5.22–5.27) and 5.29 (5.26–5.32), respectively. Serum phosphate and calcium–phosphate product concentrations were inversely associated with HOMA-IR (p for trend < 0.01). Multivariable-adjusted means (95% CI) of HOMA-IR for the lowest and highest quartiles of serum phosphate were 1.04 (0.99–1.09) and 0.72 (0.69–0.76), respectively. The corresponding values for calcium–phosphate product were 1.04 (0.99–1.09) and 0.73 (0.69–0.77), respectively. The current findings suggest that higher serum calcium and lower serum phosphate concentrations are associated with IR among apparently healthy adults.
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Affiliation(s)
- Shamima Akter
- Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo 162-8655, Japan; (A.N.); (T.M.)
- Correspondence: ; Tel.: +81-3-3202-7181; Fax: +81-3-3202-7364
| | - Masafumi Eguchi
- Department of Health Administration, Furukawa Electric Corporation, Tokyo 100-8322, Japan; (M.E.); (T.K.); (I.K.)
| | - Takeshi Kochi
- Department of Health Administration, Furukawa Electric Corporation, Tokyo 100-8322, Japan; (M.E.); (T.K.); (I.K.)
| | - Isamu Kabe
- Department of Health Administration, Furukawa Electric Corporation, Tokyo 100-8322, Japan; (M.E.); (T.K.); (I.K.)
| | - Akiko Nanri
- Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo 162-8655, Japan; (A.N.); (T.M.)
- Department of Food and Health Sciences, Fukuoka Women’s University, Fukuoka 813-8529, Japan
| | - Tetsuya Mizoue
- Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo 162-8655, Japan; (A.N.); (T.M.)
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Circulating calcium levels and the risk of type 2 diabetes: a systematic review and meta-analysis. Br J Nutr 2020; 122:376-387. [PMID: 31208474 DOI: 10.1017/s0007114519001430] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abnormal Ca homeostasis has been associated with impaired glucose metabolism. However, the epidemiological evidence is controversial. We aimed to assess the association between circulating Ca levels and the risk of type 2 diabetes mellitus (T2DM) or abnormal glucose homeostasis through conducting a systematic review and meta-analysis. Eligible studies were identified by searching electronic database (PubMed, Embase and Google Scholar) and related references with de novo results from primary studies up to December 2018. A random-effects meta-analysis was performed to estimate the weighted relative risks (RR) and 95 % CI for the associations. The search yielded twenty eligible publications with eight cohort studies identified for the meta-analysis, which included a total of 89 165 participants. Comparing the highest with the lowest category of albumin-adjusted serum Ca, the pooled RR was 1·14 (95 % CI 1·05, 1·24) for T2DM (n 51 489). Similarly, serum total Ca was associated with incident T2DM (RR 1·25; 95 % CI 1·10, 1·42) (n 64 502). Additionally, the adjusted RR for 1 mg/dl increments in albumin-adjusted serum Ca or serum total Ca levels was 1·16 (95 % CI 1·07, 1·27) and 1·19 (95 % CI 1·11, 1·28), respectively. The observed associations remained with the inclusion of a cohort study with ionised Ca as the exposure. However, data pooled from neither case-control (n 4) nor cross-sectional (n 8) studies manifested a significant correlation between circulating Ca and glucose homeostasis. In conclusion, accumulated data from the cohort studies suggest that higher circulating Ca levels are associated with an augmented risk of T2DM.
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7
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Association between Serum Calcium and Risk of Cardiometabolic Disease among Community-dwelling Adults in Taiwan. Sci Rep 2020; 10:3192. [PMID: 32081877 PMCID: PMC7035351 DOI: 10.1038/s41598-020-60209-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 02/10/2020] [Indexed: 11/26/2022] Open
Abstract
Serum calcium, although only comprising 1% of total body calcium, is involved in intracellular signal pathways, vascular dilatation/constriction, and muscle contraction, which are crucial for insulin secretion, cholesterol catabolism, and blood pressure regulation. As far as we know, research on the relationship between serum calcium level and metabolic syndrome (MetS), diabetes, and hypertension in one longitudinal study is rare. Owing to the crucial role of serum calcium in human cardiometabolic physiology and lack of related study so far, this study aims to describe the relationship between serum calcium level and the incidence of MetS, diabetes, and hypertension. During the period 2010–2016, there are two parts to our study: cross-sectional analysis and longitudinal analysis. Logistic regression was applied for cross-sectional analysis of the association between serum calcium level or albumin-corrected calcium (ACCA) and the prevalence of MetS, diabetes, or hypertension. Receiver operating characteristic (ROC) curve analysis was used for calculating of optimal cut-off value of serum calcium and ACCA. Cox proportional regression for development of MetS, diabetes, and hypertension according to different cut-off values of serum calcium level and ACCA were conducted. At baseline, there were 27,364 participants in our study. Serum calcium level had positive association with diabetes in the total population, male, and female. ACCA level had positive association with diabetes in the total population, male, and female. In unadjusted and multivariate Cox proportional hazard models, serum calcium level was associated with increased risk of incident MetS in the total population and male. ACCA was associated with increased risk of incident MetS in the total population and male. ACCA was associated with increased risk of incident diabetes in the total population and male participants. This study describes the relationship between serum calcium level and the incidence of MetS, diabetes, and hypertension. Higher serum calcium level is associated with increased risk of MetS, diabetes, and hypertension.
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Brey CW, Akbari-Alavijeh S, Ling J, Sheagley J, Shaikh B, Al-Mohanna F, Wang Y, Gaugler R, Hashmi S. Salts and energy balance: A special role for dietary salts in metabolic syndrome. Clin Nutr 2018; 38:1971-1985. [PMID: 30446179 DOI: 10.1016/j.clnu.2018.10.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/20/2018] [Accepted: 10/28/2018] [Indexed: 01/01/2023]
Abstract
BACKGROUND Dietary salts sodium (Na+), potassium (K+), magnesium (Mg2+), and calcium (Ca2+) are important in metabolic diseases. Yet, we do not have sufficient understanding on the salts global molecular network in these diseases. In this systematic review we have pooled information to identify the general effect of salts on obesity, insulin resistance and hypertension. AIMS To assess the roles of salts in metabolic disorders by focusing on their individual effect and the network effect among these salts. METHODS We searched articles in PubMed, EMBASE and Google Scholar. We selected original laboratory research, systematic reviews, clinical trials, observational studies and epidemiological data that focused on dietary salts and followed the preferred reporting items for systematic review in designing the present systematic review. RESULTS From the initial search of 2898 studies we selected a total of 199 articles that met our inclusion criteria and data extraction. Alterations in metabolic pathways associated with the sensitivity of sodium, potassium, magnesium and calcium may lead to obesity, hypertension, and insulin resistance. We found that the results of most laboratory research, animal studies and clinical trials are coherent but some research outcome are either inconsistent or inconclusive. CONCLUSION Important of salts in metabolic disorder is evident. In order to assess the effects of dietary salts in metablic diseases, environmental factors, dietary habits, physical activity, and the microbiome, should be considered in any study. Although interest in this area of research continues to grow, the challenge is to integrate the action of these salts in metabolic syndrom.
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Affiliation(s)
| | - Safoura Akbari-Alavijeh
- Laboratory of Developmental Biology, Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ, 08901, USA
| | - Jun Ling
- Department of Basic Sciences, Geisinger Commonwealth School of Medicine, 525 Pine Street, Scranton, PA, 18509, USA
| | - Jordan Sheagley
- Department of Basic Sciences, Geisinger Commonwealth School of Medicine, 525 Pine Street, Scranton, PA, 18509, USA
| | - Bilal Shaikh
- Laboratory of Developmental Biology, Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ, 08901, USA
| | | | - Yi Wang
- Laboratory of Developmental Biology, Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ, 08901, USA
| | - Randy Gaugler
- Laboratory of Developmental Biology, Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ, 08901, USA
| | - Sarwar Hashmi
- Laboratory of Developmental Biology, Center for Vector Biology, Rutgers University, 180 Jones Avenue, New Brunswick, NJ, 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, & Health, Rutgers University, USA.
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9
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Parsanathan R, Maria Joseph A, Karundevi B. Postnatal exposure to di-(2-ethylhexyl)phthalate alters cardiac insulin signaling molecules and GLUT4 Ser488 phosphorylation in male rat offspring. J Cell Biochem 2018; 120:5802-5812. [PMID: 30362281 DOI: 10.1002/jcb.27866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 09/19/2018] [Indexed: 01/16/2023]
Abstract
Di-(2-ethylhexyl)phthalate (DEHP), a distinctive endocrine-disrupting chemical, is widely used as a plasticizer in a variety of consumer products. It can easily cross the placenta and enter breast milk and then it is rapidly absorbed by offspring. Since it is generally accepted that individuals are more sensitive to chemical exposure during vital developmental periods, we investigated whether DEHP exposure during lactation affects cardiac insulin signaling and glucose homeostasis in the F1 male rat offspring at postnatal day 22 (PND22). Lactating Wistar rats were administered with DEHP (1, 10, and 100 mg/kg/d) or olive oil from lactation day 1 to 21 by oral gavage. All the male pups were perfused and killed on PND22. On the day before the killing, they were kept for fasting overnight and blood was collected. The cardiac muscle was dissected out, washed in ice-cold physiological saline repeatedly and used for the assay of various parameters. DEHP-exposed offspring had significantly lower body weight than the control. DEHP-exposed offspring showed elevated blood glucose, decreased 14 C-2-deoxyglucose uptake and 14 C-glucose oxidation in cardiac muscle at PND22. The concentration of upstream insulin signaling molecules such as insulin receptor subunit β (InsRβ) and insulin receptor substrate 1 (IRS1) were downregulated in DEHP-exposed offspring. However, no significant alterations were observed in protein kinase B (Akt) and Akt substrate of 160 kDa (AS160). Surprisingly, phosphorylation of IRS1 Tyr632 and Akt Ser473 were diminished. Low levels of glucose transporter type 4 (GLUT4) protein and increased GLUT4 Ser488 phosphorylation which decreases its intrinsic activity and translocation towards plasma membrane were also recorded. Lactational DEHP exposure predisposes F 1 male offspring to cardiac glucometabolic disorders at PND22, which may impair cardiac function.
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Affiliation(s)
- Rajesh Parsanathan
- Department of Endocrinology, Dr ALM Post Graduate Institute of Basic Medical Sciences University of Madras, Taramani, India
| | - Angelaalincy Maria Joseph
- Department of Endocrinology, Dr ALM Post Graduate Institute of Basic Medical Sciences University of Madras, Taramani, India
| | - Balasubramanian Karundevi
- Department of Endocrinology, Dr ALM Post Graduate Institute of Basic Medical Sciences University of Madras, Taramani, India
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Wright LE, Vecellio Reane D, Milan G, Terrin A, Di Bello G, Belligoli A, Sanna M, Foletto M, Favaretto F, Raffaello A, Mammucari C, Nitti D, Vettor R, Rizzuto R. Increased mitochondrial calcium uniporter in adipocytes underlies mitochondrial alterations associated with insulin resistance. Am J Physiol Endocrinol Metab 2017; 313:E641-E650. [PMID: 28790027 PMCID: PMC6109647 DOI: 10.1152/ajpendo.00143.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 08/02/2017] [Accepted: 08/04/2017] [Indexed: 01/14/2023]
Abstract
Intracellular calcium influences an array of pathways and affects cellular processes. With the rapidly progressing research investigating the molecular identity and the physiological roles of the mitochondrial calcium uniporter (MCU) complex, we now have the tools to understand the functions of mitochondrial Ca2+ in the regulation of pathophysiological processes. Herein, we describe the role of key MCU complex components in insulin resistance in mouse and human adipose tissue. Adipose tissue gene expression was analyzed from several models of obese and diabetic rodents and in 72 patients with obesity as well as in vitro insulin-resistant adipocytes. Genetic manipulation of MCU activity in 3T3-L1 adipocytes allowed the investigation of the role of mitochondrial calcium uptake. In insulin-resistant adipocytes, mitochondrial calcium uptake increased and several MCU components were upregulated. Similar results were observed in mouse and human visceral adipose tissue (VAT) during the progression of obesity and diabetes. Intriguingly, subcutaneous adipose tissue (SAT) was spared from overt MCU fluctuations. Furthermore, MCU expression returned to physiological levels in VAT of patients after weight loss by bariatric surgery. Genetic manipulation of mitochondrial calcium uptake in 3T3-L1 adipocytes demonstrated that changes in mitochondrial calcium concentration ([Ca2+]mt) can affect mitochondrial metabolism, including oxidative enzyme activity, mitochondrial respiration, membrane potential, and reactive oxygen species formation. Finally, our data suggest a strong relationship between [Ca2+]mt and the release of IL-6 and TNFα in adipocytes. Altered mitochondrial calcium flux in fat cells may play a role in obesity and diabetes and may be associated with the differential metabolic profiles of VAT and SAT.
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Affiliation(s)
- Lauren E Wright
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | | | - Gabriella Milan
- Endocrine-Metabolic Laboratory, Department of Medicine, University of Padua, Padua, Italy; and
| | - Anna Terrin
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Giorgia Di Bello
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Anna Belligoli
- Endocrine-Metabolic Laboratory, Department of Medicine, University of Padua, Padua, Italy; and
| | - Marta Sanna
- Endocrine-Metabolic Laboratory, Department of Medicine, University of Padua, Padua, Italy; and
| | - Mirto Foletto
- Department of Surgical, Oncological and Gastroenterological Sciences, University of Padua, and Surgery Branch, Padua Hospital, Padua, Italy
| | - Francesca Favaretto
- Endocrine-Metabolic Laboratory, Department of Medicine, University of Padua, Padua, Italy; and
| | - Anna Raffaello
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | | | - Donato Nitti
- Department of Surgical, Oncological and Gastroenterological Sciences, University of Padua, and Surgery Branch, Padua Hospital, Padua, Italy
| | - Roberto Vettor
- Endocrine-Metabolic Laboratory, Department of Medicine, University of Padua, Padua, Italy; and
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, Italy;
- Neuroscience Institute, National Research Council, Padua, Italy
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Parker L, Levinger I, Mousa A, Howlett K, de Courten B. Plasma 25-Hydroxyvitamin D Is Related to Protein Signaling Involved in Glucose Homeostasis in a Tissue-Specific Manner. Nutrients 2016; 8:nu8100631. [PMID: 27754361 PMCID: PMC5084018 DOI: 10.3390/nu8100631] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/25/2016] [Accepted: 10/03/2016] [Indexed: 02/06/2023] Open
Abstract
Vitamin D has been suggested to play a role in glucose metabolism. However, previous findings are contradictory and mechanistic pathways remain unclear. We examined the relationship between plasma 25-hydroxyvitamin D (25(OH)D), insulin sensitivity, and insulin signaling in skeletal muscle and adipose tissue. Seventeen healthy adults (Body mass index: 26 ± 4; Age: 30 ± 12 years) underwent a hyperinsulinemic-euglycemic clamp, and resting skeletal muscle and adipose tissue biopsies. In this cohort, the plasma 25(OH)D concentration was not associated with insulin sensitivity (r = 0.19, p = 0.56). However, higher plasma 25(OH)D concentrations correlated with lower phosphorylation of glycogen synthase kinase-3 (GSK-3) αSer21 and βSer9 in skeletal muscle (r = −0.66, p = 0.015 and r = −0.53, p = 0.06, respectively) and higher GSK-3 αSer21 and βSer9 phosphorylation in adipose tissue (r = 0.82, p < 0.01 and r = 0.62, p = 0.042, respectively). Furthermore, higher plasma 25(OH)D concentrations were associated with greater phosphorylation of both protein kinase-B (AktSer473) (r = 0.78, p < 0.001) and insulin receptor substrate-1 (IRS-1Ser312) (r = 0.71, p = 0.01) in adipose tissue. No associations were found between plasma 25(OH)D concentration and IRS-1Tyr612 phosphorylation in skeletal muscle and adipose tissue. The divergent findings between muscle and adipose tissue with regard to the association between 25(OH)D and insulin signaling proteins may suggest a tissue-specific interaction with varying effects on glucose homeostasis. Further research is required to elucidate the physiological relevance of 25(OH)D in each tissue.
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Affiliation(s)
- Lewan Parker
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne VIC 8001, Australia.
| | - Itamar Levinger
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne VIC 8001, Australia.
| | - Aya Mousa
- Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, MHRP, 43-51 Kanooka Grove, Clayton VIC 3168, Australia.
| | - Kirsten Howlett
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Waurn Ponds VIC 3217, Australia.
| | - Barbora de Courten
- Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, MHRP, 43-51 Kanooka Grove, Clayton VIC 3168, Australia.
- Diabetes and Vascular Medicine Unit, Monash Health, Locked Bag 29, Clayton VIC 3168, Australia.
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12
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Rooney MR, Pankow JS, Sibley SD, Selvin E, Reis JP, Michos ED, Lutsey PL. Serum calcium and incident type 2 diabetes: the Atherosclerosis Risk in Communities (ARIC) study. Am J Clin Nutr 2016; 104:1023-1029. [PMID: 27510541 PMCID: PMC5039808 DOI: 10.3945/ajcn.115.130021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 07/06/2016] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Elevated serum calcium has been associated with a variety of metabolic abnormalities and may be associated with a greater risk of diabetes. OBJECTIVE The purpose of this study was to test the hypothesis that serum calcium concentration is positively and independently associated with the incidence of diabetes and to evaluate the association of calcium-sensing receptor (CaSR) gene single nucleotide polymorphism (SNP) rs1801725 with incident diabetes. DESIGN Atherosclerosis Risk in Communities study participants free of diabetes at baseline (n = 12,800; mean age: 53.9 y; 22.6% black) were studied for incident diabetes. Serum calcium was measured at baseline and corrected for serum albumin. Diabetes was defined by use of glucose concentrations, self-report, or medication use. Cox proportional hazards regression was used. RESULTS During a mean 8.8 y of follow-up, 1516 cases of diabetes were reported. Participants in the highest compared with lowest calcium quintile were at greater risk of incident diabetes after adjustment for demographic and lifestyle factors [HR (95% CI): 1.34 (1.14, 1.57); P-trend across quintiles <0.0001] and with further adjustment for waist circumference and body mass index [1.26 (1.07, 1.48); P-trend = 0.004]. Additional adjustment for biomarkers on the metabolic pathway (e.g., 25-hydroxyvitamin D, parathyroid hormone, phosphorus) had little impact. The calcium-diabetes association was statistically significant in blacks [1.48 (1.11, 1.98); P-trend = 0.002] but not whites [1.17 (0.96, 1.43); P-trend = 0.17] after adjustment for adiposity. In whites, CaSR gene SNP rs1801725 was associated with serum calcium but not with risk of diabetes. CONCLUSIONS Consistent with 3 previous cohort studies, elevated serum calcium was found to be associated with a greater risk of type 2 diabetes. Further research is needed to understand the role, if any, that calcium plays in the pathogenesis of diabetes.
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Affiliation(s)
| | | | | | - Elizabeth Selvin
- Department of Epidemiology and Welch Center for Prevention, Epidemiology, and Clinical Research, and
| | - Jared P Reis
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, Bethesda, MD
| | - Erin D Michos
- Department of Epidemiology and Welch Center for Prevention, Epidemiology, and Clinical Research, and Division of Cardiology, Johns Hopkins University, Baltimore, MD; and
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Chatterjee R, Lin PH. Serum calcium and its complex association with incident type 2 diabetes. Am J Clin Nutr 2016; 104:957-958. [PMID: 27629050 PMCID: PMC5039814 DOI: 10.3945/ajcn.116.143321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Ranee Chatterjee
- Department of Medicine, Duke University School of Medicine, Durham, NC
| | - Pao-Hwa Lin
- Department of Medicine, Duke University School of Medicine, Durham, NC
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Cho HS, Lee SW, Shin J, Moon SD, Han JH, Cha BY, Kim ES. Association of serum calcium concentrations with fibrinogen and homocysteine in nondiabetic Korean subjects. Medicine (Baltimore) 2016; 95:e3899. [PMID: 27310988 PMCID: PMC4998474 DOI: 10.1097/md.0000000000003899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Considerable evidence shows that increased serum calcium levels are associated with metabolic disorders, cardiovascular disease, and increased mortality. This study investigated whether serum calcium, within a normal range, is significantly associated with serum fibrinogen and homocysteine, markers of increased cardiovascular disease risk in nondiabetic Korean subjects.A cross-sectional analysis was performed on 1096 subjects (mean age, 55.1 ± 11.1 years; 36.1% women) undergoing a general health checkup. Serum biochemistry was analyzed including serum albumin-corrected calcium (Cac), insulin resistance (IR, using homeostasis model assessment [HOMA]), fibrinogen, and homocysteine.Compared with patients within the lowest Cac quartile, those with higher Cac levels had increased fibrinogen and homocysteine levels as well as an increased proportion of smoking, dyslipidemia, and HOMA-IR. Correlation analyses revealed linear relationships for Cac with fibrinogen and homocysteine in both genders. After adjustment for confounding factors, serum Cac was significantly associated with high fibrinogen (odds ratio [OR] for the highest vs the lowest quartile = 1.76, 95% confidence interval [CI] = 1.09-2.83, P = 0.02) and homocysteine (OR = 1.83, 95% CI = 1.07-3.11, P = 0.027). Multivariate regression models showed that Cac was linearly associated with fibrinogen (standardized β = 0.14, P < 0.001) and homocysteine (standardized β = 0.07, P = 0.009).High normal calcium concentrations were independently associated with increased levels of fibrinogen and homocysteine. Further investigation is needed to validate whether slightly increased calcium levels within the normal range indicate a higher risk of cardiovascular disease.
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Affiliation(s)
- Hyun Sun Cho
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Health Promotion Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Sung Won Lee
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Division of Hepatology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Juyoung Shin
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Health Promotion Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Sung Dae Moon
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Je Ho Han
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Bong Yun Cha
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Eun Sook Kim
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
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15
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Shin JY, Kim MJ, Kim ES, Mo EY, Moon SD, Han JH, Cha BY. Association between serum calcium and phosphorus concentrations with non-alcoholic fatty liver disease in Korean population. J Gastroenterol Hepatol 2015; 30:733-41. [PMID: 25318838 DOI: 10.1111/jgh.12832] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/09/2014] [Indexed: 01/12/2023]
Abstract
BACKGROUND AND AIM Growing evidence suggests that non-alcoholic fatty liver disease (NAFLD) is interrelated with renal dysfunction and disturbed bone metabolism, both of which play a key role in calcium and phosphorus homeostasis. We investigated the association between NAFLD and serum calcium and phosphorus levels in Korean subjects. METHODS We performed a cross-sectional analysis of 16,592 subjects undergoing a general health checkup. NAFLD was assessed based on ultrasonographically detected fatty liver in the absence of excessive alcohol consumption and other causes of liver disease. RESULTS The proportion of the population with fatty liver detected by ultrasonography was 43.2% for males and 17.6% for females. We observed that a higher serum albumin-corrected calcium (Ca(c)) level was associated with smoking, hypertension, and unfavorable metabolic parameters in both genders, but the serum phosphorus levels showed an inconsistent correlation with metabolic abnormalities. After adjusting for age, gender, waist circumference, body mass index, smoking status, exercise, diabetes, hypertension, lipid profiles, and renal function, serum Cac , phosphorus, and Cac -phosphorus products were independent risk factors for fatty liver (odds ratio [OR]: 1.71, 95% confidence interval [CI]: 1.49-1.95, P < 0.001; OR: 1.34, 95% CI: 1.22-1.48, P < 0.001; and OR: 1.20, 95% CI: 1.14-1.26, P < 0.001, respectively), and the risk of fatty liver increased in a graded manner over the quartiles. CONCLUSION Serum calcium and phosphorus levels are significantly associated with NAFLD. Further investigation is needed to verify whether calcium and phosphorus levels indicate a higher risk of NAFLD.
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Affiliation(s)
- Ju Young Shin
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Catholic University of Korea College of Medicine, Incheon St. Mary's Hospital, Incheon, Korea
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Becerra-Tomás N, Estruch R, Bulló M, Casas R, Díaz-López A, Basora J, Fitó M, Serra-Majem L, Salas-Salvadó J. Increased serum calcium levels and risk of type 2 diabetes in individuals at high cardiovascular risk. Diabetes Care 2014; 37:3084-91. [PMID: 25139884 DOI: 10.2337/dc14-0898] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Insulin resistance and secretion depend on calcium homeostasis. Cross-sectional studies have associated elevated serum calcium levels with markers of impaired glucose metabolism. However, only one prospective cohort study has demonstrated an increased risk of diabetes in individuals with increased serum calcium concentrations. The aim of the current study was to prospectively investigate the association between albumin-adjusted serum calcium concentrations and type 2 diabetes in subjects at high cardiovascular risk. RESEARCH DESIGN AND METHODS Prospective assessment of participants from two Spanish PREDIMED study centers where serum calcium levels were measured at baseline and yearly during follow-up. Multivariate-adjusted Cox regression models were fitted to assess associations between baseline and changes during follow-up in serum calcium levels and relative risk of diabetes incidence. RESULTS After a median follow-up of 4.78 years, 77 new cases of type 2 diabetes occurred. An increase in serum calcium levels during follow-up was related to an increased risk of diabetes. In comparison with individuals in the lowest tertile (-0.78 ± 0.29 mg/dL), the hazard ratio (HR) and 95% CI for diabetes incidence in individuals in the higher tertile of change (0.52 ± 0.13 mg/dL) during follow-up was 3.48 (95% CI 1.48-8.17; P for trend = 0.01). When albumin-adjusted serum calcium was analyzed as a continuous variable, per 1 mg/dL increase, the HR of diabetes incidence was 2.87 (95% CI 1.18-6.96; P value = 0.02). These associations remained significant after individuals taking calcium supplements or having calcium levels out of normal range had been excluded. CONCLUSIONS An increase in serum calcium concentrations is associated with an increased risk of type 2 diabetes in individuals at high cardiovascular risk.
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Affiliation(s)
- Nerea Becerra-Tomás
- Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Reus, Spain CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
| | - Ramón Estruch
- CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain Department of Internal Medicine, August Pi i Sunyer Institute of Biomedical Research, Hospital Clinic, University of Barcelona, Barcelona, Spain
| | - Mònica Bulló
- Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Reus, Spain CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
| | - Rosa Casas
- CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain Department of Internal Medicine, August Pi i Sunyer Institute of Biomedical Research, Hospital Clinic, University of Barcelona, Barcelona, Spain
| | - Andrés Díaz-López
- Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Reus, Spain CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
| | - Josep Basora
- Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Reus, Spain CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
| | - Montserrat Fitó
- CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain Cardiovascular Risk and Nutrition (Regicor Study Group), Hospital del Mar Medical Research Institute, Barcelona Biomedical Research Park, Barcelona, Spain
| | - Lluis Serra-Majem
- CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain Department of Clinical Sciences, University of Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Jordi Salas-Salvadó
- Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Reus, Spain CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
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Rajesh P, Balasubramanian K. Phthalate exposure in utero causes epigenetic changes and impairs insulin signalling. J Endocrinol 2014; 223:47-66. [PMID: 25232145 DOI: 10.1530/joe-14-0111] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Di-(2-ethylhexyl)phthalate (DEHP) is an endocrine-disrupting chemical (EDC), widely used as a plasticiser. Developmental exposure to EDCs could alter epigenetic programming and result in adult-onset disease. We investigated whether DEHP exposure during development affects glucose homoeostasis in the F1 offspring as a result of impaired insulin signal transduction in gastrocnemius muscle. Pregnant Wistar rats were administered DEHP (0, 1, 10 and 100 mg/kg per day) from embryonic days 9-21 orally. DEHP-exposed offspring exhibited elevated blood glucose, impaired serum insulin, glucose tolerance and insulin tolerance, along with reduced insulin receptor, glucose uptake and oxidation in the muscle at postnatal day 60. The levels of insulin signalling molecules and their phosphorylation were down-regulated in DEHP-exposed offspring. However, phosphorylated IRS1(Ser636/639), which impedes binding of downstream effectors and the negative regulator (PTEN) of PIP3, was increased in DEHP-exposed groups. Down-regulation of glucose transporter 4 (Glut4 (Slc2a4)) gene expression and increased GLUT4(Ser488) phosphorylation, which decreases its intrinsic activity and translocation towards the plasma membrane, were recorded. Chromatin immunoprecipitation assays detected decreased MYOD binding and increased histone deacetylase 2 interaction towards Glut4, indicative of the tight chromatin structure at the Glut4 promoter. Increased DNMTs and global DNA methylation levels were also observed. Furthermore, methylation of Glut4 at the MYOD-binding site was increased in DEHP-exposed groups. These findings indicate that, gestational DEHP exposure predisposes F1 offspring to glucometabolic dysfunction at adulthood by down-regulating the expression of critical genes involved in the insulin signalling pathway. Furthermore, DEHP-induced epigenetic alterations in Glut4 appear to play a significant role in disposition towards this metabolic abnormality.
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Affiliation(s)
- Parsanathan Rajesh
- Department of EndocrinologyDr ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai 600 113, India
| | - Karundevi Balasubramanian
- Department of EndocrinologyDr ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai 600 113, India
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Conditioning increases the gain of contraction-induced sarcolemmal substrate transport in ultra-endurance racing sled dogs. PLoS One 2014; 9:e103087. [PMID: 25075856 PMCID: PMC4116179 DOI: 10.1371/journal.pone.0103087] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 06/27/2014] [Indexed: 12/05/2022] Open
Abstract
Endurance exercise relies on transsarcolemmal flux of substrates in order to avoid depletion of intramuscular reserves. Previous studies of endurance trained sled dogs have shown a remarkable capacity of these dogs to adapt rapidly to endurance exercise by decreasing the utilization of intramuscular reserves. The current study tested the hypothesis that the dogs' glycogen-sparing phenotype is due to increased sarcolemmal transport of glucose and fatty acids. Basal and exercise-induced transport of glucose and fatty acids into sarcolemmal vesicles was evaluated in racing sled dogs prior to and after 7 months of exercise conditioning. Sarcolemmal substrate transport capacity was measured using sarcolemmal vesicles and radiolabelled substrates, and transporter abundance was measured using Western blot quantification in whole muscle homogenates and the sarcolemmal vesicle preparations. Conditioning resulted in increased basal and exercise-induced transport of both glucose and palmitate. Neither acute exercise nor conditioning resulted in changes in muscle content of GLUT4 or FAT/CD36, but conditioning did result in decreased abundance of both transporters in the sarcolemmal vesicles used for the basal transport assays, and this decrease was further amplified in the vesicles used for the exercise-induced transport assays. These results demonstrate conditioning-induced increases in sarcolemmal transport of oxidizable substrates, as well as increased gain of exercise-induced sarcolemmal transport of these substrates. These results further indicate that increased sarcolemmal transport of oxidizable substrates may be due to either an increased intrinsic capacity of the existing transporters or to a different population of transporters from those investigated.
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Rajesh P, Sathish S, Srinivasan C, Selvaraj J, Balasubramanian K. Phthalate is associated with insulin resistance in adipose tissue of male rat: role of antioxidant vitamins. J Cell Biochem 2013; 114:558-69. [PMID: 22991202 DOI: 10.1002/jcb.24399] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 09/06/2012] [Indexed: 01/11/2023]
Abstract
Diethyl hexyl phthalate (DEHP) is a plasticizer, commonly used in a variety of products, including lubricants, perfumes, hairsprays and cosmetics, construction materials, wood finishers, adhesives, floorings and paints. DEHP is an endocrine disruptor and it has a continuum of influence on various organ systems in human beings and experimental animals. However, specific effects of DEHP on insulin signaling in adipose tissue are not known. Adult male albino rats of Wistar strain were divided into four groups. Control, DEHP treated (dissolved in olive oil at a dose of 10, and 100 mg/kg body weight, respectively, once daily through gastric intubations for 30 days) and DEHP + vitamin E (50 mg/kg body weight) and C (100 mg/kg body weight) dissolved in olive oil and distilled water, respectively, once daily through gastric intubations for 30 days. After the completion of treatment, adipose tissue was dissected out to assess various parameters. DEHP treatment escalated H(2)O(2) and hydroxyl radical levels as well as lipid peroxidation in the adipose tissue. DEHP impaired the expression of insulin signaling molecules and their phosphorelay pathways leading to diminish plasma membrane GLUT4 level and thus decreased glucose uptake and oxidation. Blood glucose level was elevated as a result of these changes. Supplementation of vitamins (C & E) prevented the DEHP-induced changes. It is concluded that DEHP-induced ROS and lipid peroxidation disrupts the insulin signal transduction in adipose tissue and favors glucose intolerance. Antioxidant vitamins have a protective role against the adverse effect of DEHP.
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Affiliation(s)
- Parsanathan Rajesh
- Department of Endocrinology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Sekkizhar Campus, Taramani, Chennai 600113, India
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Effect of Opuntia humifusa supplementation and acute exercise on insulin sensitivity and associations with PPAR-γ and PGC-1α protein expression in skeletal muscle of rats. Int J Mol Sci 2013; 14:7140-54. [PMID: 23538842 PMCID: PMC3645680 DOI: 10.3390/ijms14047140] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/21/2013] [Accepted: 03/25/2013] [Indexed: 12/15/2022] Open
Abstract
This study examined whether Opuntia humifusa (O. humifusa), which is a member of the Cactaceae family, supplementation and acute swimming exercise affect insulin sensitivity and associations with PPAR-γ and PGC-1α protein expression in rats. Thirty-two rats were randomly divided into four groups (HS: high fat diet sedentary group, n = 8; HE: high fat diet acute exercise group, n = 8; OS: 5% O. humifusa supplemented high fat diet sedentary group, n = 8; OE: 5% O. humifusa supplemented high fat diet acute exercise group, n = 8). Rats in the HE and OE swam for 120 min. before being sacrificed. Our results indicated that serum glucose level, fasting insulin level and homeostasis model assessment of insulin resistance (HOMA-IR) in OS were significantly lower compared to those of the HS (p < 0.01, p < 0.05, p < 0.05). In addition, PPAR-γ protein expression in the OS and OE was significantly higher than that of the HS and HE, respectively (p < 0.05, p < 0.01). PGC-1α and GLUT-4 protein expressions in the OS were significantly higher compared to those of the HS (p < 0.05, p < 0.05). From these results, O. humifusa supplementation might play an important role for improving insulin sensitivity through elevation of PPAR-γ, PGC-1α, and GLUT-4 protein expression in rat skeletal muscle.
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Effective components screening and anti-myocardial infarction mechanism study of the Chinese medicine NSLF6 based on "system to system" mode. J Transl Med 2012; 10:26. [PMID: 22316391 PMCID: PMC3305499 DOI: 10.1186/1479-5876-10-26] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 02/08/2012] [Indexed: 11/12/2022] Open
Abstract
Background Shuanglong formula (SLF), a Chinese medicine composed of panax ginseng and salvia miltiorrhiza exhibited significant effect in the treatment of myocardial infarction (MI) in clinical. Because of the complex nature and lack of stringent quality control, it's difficult to explain the action mechanism of SLF. Method In this study, we present a "system to system" (S2S) mode. Based on this mode, SLF was simplified successively through bioactivity-guided screening to achieve an optimized minimal phytochemical composition (new formula NSLF6) while maintaining its curative effect for MI. Results Pharmacological test combining with the study of systems biology show that NSLF6 has activity for treatment MI through synergistic therapeutic efficacies between total ginsenosides and total salvianolic acids via promoting cardiac cell regeneration and myocardial angiogenesis, antagonistic myocardial cell oxidative damage. Conclusions The present S2S mode may be an effective way for the discovery of new composite drugs from traditional medicines.
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Calcium supplementation prevents obesity, hyperleptinaemia and hyperglycaemia in adult rats programmed by early weaning. Br J Nutr 2011; 107:979-88. [PMID: 22070983 DOI: 10.1017/s0007114511003928] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It is known that Ca therapy may have anti-obesity effects. Since early weaning leads to obesity, hyperleptinaemia and insulin resistance, we studied the effect of dietary Ca supplementation in a rat model. Lactating rats were separated into two groups: early weaning (EW) - dams were wrapped with a bandage to interrupt lactation in the last 3 d of lactation and control (C) - dams whose pups had free access to milk during the entire lactation period (21 d). At 120 d, EW and C offspring were subdivided into four groups: (1) C, received standard diet; (2) CCa, received Ca supplementation (10 g of calcium carbonate/kg of rat chow); (3) EW, received standard diet; (4) EWCa, received Ca supplementation similar to CCa. The rats were killed at 180 d. The significance level was at P < 0·05. Adult EW offspring displayed hyperphagia (28 %), higher body weight (9 %) and adiposity (77 %), hyperleptinaemia (twofold increase), hypertriacylglycerolaemia (64 %), hyperglycaemia (16 %), higher insulin resistance index (38 %) and higher serum 25-hydroxyvitamin D₃ (fourfold increase), but lower adiponectinaemia:adipose tissue ratio (44 %). In addition, they showed Janus tyrosine kinase 2 and phosphorylated signal transducer and activator of transcription 3 underexpression in hypothalamus (36 and 34 %, respectively), suggesting leptin resistance. Supplementation of Ca for 2 months normalised these disorders. The EW group had no change in serum insulin, thyroxine or triiodothyronine, and Ca treatment did not alter these hormones. In conclusion, we reinforced that early weaning leads to late development of some components of the metabolic syndrome and leptin resistance. Dietary Ca supplementation seems to protect against the development of endocrine and metabolic disorders in EW offspring, maybe through vitamin D inhibition.
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Pancani T, Anderson KL, Porter NM, Thibault O. Imaging of a glucose analog, calcium and NADH in neurons and astrocytes: dynamic responses to depolarization and sensitivity to pioglitazone. Cell Calcium 2011; 50:548-58. [PMID: 21978418 DOI: 10.1016/j.ceca.2011.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/24/2011] [Accepted: 09/10/2011] [Indexed: 11/19/2022]
Abstract
Neuronal Ca(2+) dyshomeostasis associated with cognitive impairment and mediated by changes in several Ca(2+) sources has been seen in animal models of both aging and diabetes. In the periphery, dysregulation of intracellular Ca(2+) signals may contribute to the development of insulin resistance. In the brain, while it is well-established that type 2 diabetes mellitus is a risk factor for the development of dementia in the elderly, it is not clear whether Ca(2+) dysregulation might also affect insulin sensitivity and glucose utilization. Here we present a combination of imaging techniques testing the disappearance of the fluorescent glucose analog 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) as an indication of glycolytic activity in neurons and astrocytes. Our work shows that glucose utilization at rest is greater in neurons compared to astrocytes, and ceases upon activation in neurons with little change in astrocytes. Pretreatment of hippocampal cultures with pioglitazone, a drug used in the treatment of type 2 diabetes, significantly reduced glycolytic activity in neurons and enhanced it in astrocytes. This series of experiments, including Fura-2 and NADH imaging, provides results that are consistent with the idea that Ca(2+) levels may rapidly alter glycolytic activity, and that downstream events beyond Ca(2+) dysregulation with aging, may alter cellular metabolism in the brain.
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Affiliation(s)
- Tristano Pancani
- Department of Molecular and Biomedical Pharmacology, University of Kentucky Medical Center, Lexington, United States.
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Vitamin D and type 2 diabetes mellitus: Where do we stand? DIABETES & METABOLISM 2011; 37:265-72. [DOI: 10.1016/j.diabet.2011.01.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 01/05/2011] [Accepted: 01/08/2011] [Indexed: 01/25/2023]
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Saltevo J, Niskanen L, Kautiainen H, Teittinen J, Oksa H, Korpi-Hyövälti E, Sundvall J, Männistö S, Peltonen M, Mäntyselkä P, Vanhala M. Serum calcium level is associated with metabolic syndrome in the general population: FIN-D2D study. Eur J Endocrinol 2011; 165:429-34. [PMID: 21659455 DOI: 10.1530/eje-11-0066] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND The aim of this cross-sectional study was to examine the association between serum calcium and the components of metabolic syndrome (MetS). METHODS As a part of the national prevention program of diabetes in Finland (FIN-D2D), a randomly selected study population of 4500 middle-aged men and women were recruited from three central hospital district areas. Anthropometric measurements were performed by a trained nurse. An oral glucose tolerance test was performed and serum calcium and lipids were measured. We assessed current medications, physical activity, smoking, alcohol consumption, calcium intake, and vitamin D intake. The MetS was defined according to the criteria of the updated National Education Program. The study population consisted of 2896 individuals: 1396 men (62% of invited individuals) and 1500 women (66.7% of invited individuals). RESULTS The mean age was 60.3±8.3 years in men and 59.8±8.5 years in women. The prevalence of MetS was 50.7% in women and 55.8% in men. The prevalence of MetS and its components, except high-density lipoprotein (HDL)-cholesterol, increased linearly with increasing serum calcium (P<0.001), even after adjustment for age, physical activity, alcohol, vitamin D intake, calcium intake, and smoking. The threshold value for serum calcium for MetS was 2.50 mmol/l in this population. The association of MetS with total serum calcium was similar even after exclusion of patients treated with hypertensive drugs. The drug treatments for hypertension, dyslipidemia, and diabetes increased in a similar pattern. CONCLUSIONS Serum calcium level is associated with MetS and its components, except HDL-cholesterol.
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Affiliation(s)
- J Saltevo
- Department of Medicine, Central Finland Central Hospital, 40620 Jyväskylä, Finland.
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Nobre JL, Lisboa PC, Santos-Silva AP, Lima NS, Manhães AC, Nogueira-Neto JF, Cabanelas A, Pazos-Moura CC, Moura EG, de Oliveira E. Calcium supplementation reverts central adiposity, leptin, and insulin resistance in adult offspring programed by neonatal nicotine exposure. J Endocrinol 2011; 210:349-59. [PMID: 21680618 DOI: 10.1530/joe-11-0172] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Obesity is a worldwide epidemic. Calcium influences energy metabolism regulation, causing body weight loss. Because maternal nicotine exposure during lactation programs for obesity, hyperleptinemia, insulin resistance (IR), and hypothyroidism, we decided to evaluate the possible effect of dietary calcium supplementation on these endocrine dysfunctions in this experimental model. Osmotic minipumps containing nicotine solution (N: 6 mg/kg per day for 14 days) or saline (C) were s.c. implanted in lactating rats 2 days after giving birth (P2). At P120, N and C offspring were subdivided into four groups: 1) C - standard diet; 2) C with calcium supplementation (CCa, 10 g calcium carbonate/kg rat chow); 3) N - standard diet; and 4) N with calcium supplementation (NCa). Rats were killed at P180. As expected, N offspring showed higher visceral and total body fat, hyperleptinemia, lower hypothalamus leptin receptor (OB-R) content, hyperinsulinemia, and higher IR index. Also, higher tyrosine hydroxylase (TH) expression (+51%), catecholamine content (+37%), and serum 25-hydroxyvitamin D(3) (+76%) were observed in N offspring. Dietary calcium supplementation reversed adiposity, hyperleptinemia, OB-R underexpression, IR, TH overexpression, and vitamin D. However, this supplementation did not reverse hypothyroidism. In NCa offspring, Sirt1 mRNA was lower in visceral fat (-37%) and higher in liver (+42%). In conclusion, dietary calcium supplementation seems to revert most of the metabolic syndrome parameters observed in adult offspring programed by maternal nicotine exposure during lactation. It is conceivable that the reduction in fat mass per se, induced by calcium therapy, is the main mechanism that leads to the increment of insulin action.
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Affiliation(s)
- J L Nobre
- Department of Physiological Sciences, Roberto Alcantara Gomes Biology Institute, State University of Rio de Janeiro, Avenida 28 de setembro 87, Rio de Janeiro, RJ, Brazil
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Mohan S, Sheena A, Poulose N, Anilkumar G. Molecular dynamics simulation studies of GLUT4: substrate-free and substrate-induced dynamics and ATP-mediated glucose transport inhibition. PLoS One 2010; 5:e14217. [PMID: 21151967 PMCID: PMC2997047 DOI: 10.1371/journal.pone.0014217] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 11/15/2010] [Indexed: 02/03/2023] Open
Abstract
Background Glucose transporter 4 (GLUT4) is an insulin facilitated glucose transporter that plays an important role in maintaining blood glucose homeostasis. GLUT4 is sequestered into intracellular vesicles in unstimulated cells and translocated to the plasma membrane by various stimuli. Understanding the structural details of GLUT4 will provide insights into the mechanism of glucose transport and its regulation. To date, a crystal structure for GLUT4 is not available. However, earlier work from our laboratory proposed a well validated homology model for GLUT4 based on the experimental data available on GLUT1 and the crystal structure data obtained from the glycerol 3-phosphate transporter. Methodology/Principal Findings In the present study, the dynamic behavior of GLUT4 in a membrane environment was analyzed using three forms of GLUT4 (apo, substrate and ATP-substrate bound states). Apo form simulation analysis revealed an extracellular open conformation of GLUT4 in the membrane favoring easy exofacial binding of substrate. Simulation studies with the substrate bound form proposed a stable state of GLUT4 with glucose, which can be a substrate-occluded state of the transporter. Principal component analysis suggested a clockwise movement for the domains in the apo form, whereas ATP substrate-bound form induced an anti-clockwise rotation. Simulation studies suggested distinct conformational changes for the GLUT4 domains in the ATP substrate-bound form and favor a constricted behavior for the transport channel. Various inter-domain hydrogen bonds and switching of a salt-bridge network from E345-R350-E409 to E345-R169-E409 contributed to this ATP-mediated channel constriction favoring substrate occlusion and prevention of its release into cytoplasm. These data are consistent with the biochemical studies, suggesting an inhibitory role for ATP in GLUT-mediated glucose transport. Conclusions/Significance In the absence of a crystal structure for any glucose transporter, this study provides mechanistic details of the conformational changes in GLUT4 induced by substrate and its regulator.
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Affiliation(s)
- Suma Mohan
- Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, India
| | - Aswathy Sheena
- Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, India
| | - Ninu Poulose
- Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, India
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Contreras-Ferrat AE, Toro B, Bravo R, Parra V, Vásquez C, Ibarra C, Mears D, Chiong M, Jaimovich E, Klip A, Lavandero S. An inositol 1,4,5-triphosphate (IP3)-IP3 receptor pathway is required for insulin-stimulated glucose transporter 4 translocation and glucose uptake in cardiomyocytes. Endocrinology 2010; 151:4665-77. [PMID: 20685879 DOI: 10.1210/en.2010-0116] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Intracellular calcium levels ([Ca2+]i) and glucose uptake are central to cardiomyocyte physiology, yet connections between them have not been studied. We investigated whether insulin regulates [Ca2+]i in cultured cardiomyocytes, the participating mechanisms, and their influence on glucose uptake via SLC2 family of facilitative glucose transporter 4 (GLUT4). Primary neonatal rat cardiomyocytes were preloaded with the Ca2+ fluorescent dye fluo3-acetoxymethyl ester compound (AM) and visualized by confocal microscopy. Ca2+ transport pathways were selectively targeted by chemical and molecular inhibition. Glucose uptake was assessed using [3H]2-deoxyglucose, and surface GLUT4 levels were quantified in nonpermeabilized cardiomyocytes transfected with GLUT4-myc-enhanced green fluorescent protein. Insulin elicited a fast, two-component, transient increase in [Ca2+]i. Nifedipine and ryanodine prevented only the first component. The second one was reduced by inositol-1,4,5-trisphosphate (IP3)-receptor-selective inhibitors (xestospongin C, 2 amino-ethoxydiphenylborate), by type 2 IP3 receptor knockdown via small interfering RNA or by transfected Gβγ peptidic inhibitor βARKct. Insulin-stimulated glucose uptake was prevented by bis(2-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid-AM, 2-amino-ethoxydiphenylborate, and βARK-ct but not by nifedipine or ryanodine. Similarly, insulin-dependent exofacial exposure of GLUT4-myc-enhanced green fluorescent protein was inhibited by bis(2-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid-AM and xestospongin C but not by nifedipine. Phosphatidylinositol 3-kinase and Akt were also required for the second phase of Ca2+ release and GLUT4 translocation. Transfected dominant-negative phosphatidylinositol 3-kinase γ inhibited the latter. In conclusion, in primary neonatal cardiomyocytes, insulin induces an important component of Ca2+ release via IP3 receptor. This component signals to glucose uptake via GLUT4, revealing a so-far unrealized contribution of IP3-sensitive Ca2+ stores to insulin action. This pathway may influence cardiac metabolism in conditions yet to be explored in adult myocardium.
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MESH Headings
- Animals
- Animals, Newborn
- Calcium/metabolism
- Cells, Cultured
- Glucose/metabolism
- Glucose/pharmacokinetics
- Glucose Transporter Type 4/metabolism
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate/physiology
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Insulin/pharmacology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Protein Transport/drug effects
- Rats
- Rats, Sprague-Dawley
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Up-Regulation/drug effects
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Affiliation(s)
- A E Contreras-Ferrat
- Centro Estudios Moleculares de la Célula, Facultad de Medicina, and Departamento de Bioquímica y Biología Molecular, Universidad de Chile, Olivos 1007, Santiago 838-0492, Chile
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Murrow BA, Hoehn KL. Mitochondrial regulation of insulin action. Int J Biochem Cell Biol 2010; 42:1936-9. [PMID: 20837159 DOI: 10.1016/j.biocel.2010.08.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 08/21/2010] [Accepted: 08/30/2010] [Indexed: 11/28/2022]
Abstract
Insulin resistance is the prodrome of many metabolic diseases and identifying ways to correct this pathological condition is a major goal for medical research. The foremost barrier to the development of new treatments is that the precise etiology of insulin resistance is uncertain. Recent studies suggest that changes in mitochondrial structure or function drive this condition, however much of this evidence is circumstantial. This Signaling Networks in Focus article provides a brief overview of known and speculative regulatory intersections whereby mitochondrial dysfunction at the levels of lipid oxidation, oxidative stress, calcium, adenine nucleotides, and protons may regulate insulin sensitivity. If mitochondrial dysfunction underlies the origins of metabolic disease then determining the precise molecular pathway will be essential for the development of new treatment and prevention strategies.
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Affiliation(s)
- Beverley A Murrow
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
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Kennedy A, Martinez K, Chung S, LaPoint K, Hopkins R, Schmidt SF, Andersen K, Mandrup S, McIntosh M. Inflammation and insulin resistance induced by trans-10, cis-12 conjugated linoleic acid depend on intracellular calcium levels in primary cultures of human adipocytes. J Lipid Res 2010; 51:1906-17. [PMID: 20154361 DOI: 10.1194/jlr.m005447] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We previously demonstrated that trans-10, cis-12 (10,12) conjugated linoleic acid (CLA) induced inflammation and insulin resistance in primary human adipocytes by activating nuclear factor kappaB (NFkappaB) and extracellular signal-related kinase (ERK) signaling. In this study, we demonstrated that the initial increase in intracellular calcium ([Ca2+]i) mediated by 10,12 CLA was attenuated by TMB-8, an inhibitor of calcium release from the endoplasmic reticulum (ER), by BAPTA, an intracellular calcium chelator, and by D609, a phospholipase C (PLC) inhibitor. Moreover, BAPTA, TMB-8, and D609 attenuated 10,12 CLA-mediated production of reactive oxygen species (ROS), activation of ERK1/2 and cJun-NH2-terminal kinase (JNK), and induction of inflammatory genes. 10,12 CLA-mediated binding of NFkappaB to the promoters of interleukin (IL)-8 and cyclooxygenase (COX)-2 and induction of calcium-calmodulin kinase II (CaMKII) beta were attenuated by TMB-8. KN-62, a CaMKII inhibitor, also suppressed 10,12 CLA-mediated ROS production and ERK1/2 and JNK activation. Additionally, KN-62 attenuated 10,12 CLA induction of inflammatory and integrated stress response genes, increase in prostaglandin F2alpha, and suppression of peroxisome proliferator activated receptor gamma protein levels and insulin-stimulated glucose uptake. These data suggest that 10,12 CLA increases inflammation and insulin resistance in human adipocytes, in part by increasing [Ca2+]i levels, particularly calcium from the ER.
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Affiliation(s)
- Arion Kennedy
- Department of Nutrition, University of North Carolina at Greensboro, Greensboro, NC, USA
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Ullah MI, Uwaifo GI, Nicholas WC, Koch CA. Does vitamin d deficiency cause hypertension? Current evidence from clinical studies and potential mechanisms. Int J Endocrinol 2009; 2010:579640. [PMID: 20049157 PMCID: PMC2798112 DOI: 10.1155/2010/579640] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 07/26/2009] [Accepted: 08/29/2009] [Indexed: 11/25/2022] Open
Abstract
Vitamin D deficiency is widely prevalent across all ages, races, geographical regions, and socioeconomic strata. In addition to its important role in skeletal development and calcium homeostasis, several recent studies suggest its association with diabetes, hypertension, cardiovascular disease, certain types of malignancy, and immunologic dysfunction. Here, we review the current evidence regarding an association between vitamin D deficiency and hypertension in clinical and epidemiological studies. We also look into plausible biological explanations for such an association with the renin-angiotensin-aldosterone system and insulin resistance playing potential roles. Taken together, it appears that more studies in more homogeneous study populations are needed before a firm conclusion can be reached as to whether vitamin D deficiency causes or aggravates hypertension and whether vitamin D supplementation is safe and exerts cardioprotective effects. The potential problems with bias and confounding factors present in previous epidemiological studies may be overcome or minimized by well designed randomized controlled trials in the future.
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Affiliation(s)
- M. Iftekhar Ullah
- Division of General Internal Medicine and Hypertension, Department of Medicine, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Gabriel I. Uwaifo
- Division of Endocrinology, University of Mississippi Medical Center, Jackson, MS 39216, USA
- Department of Medicine, G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS 39216, USA
| | - William C. Nicholas
- Division of Endocrinology, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Christian A. Koch
- Division of Endocrinology, University of Mississippi Medical Center, Jackson, MS 39216, USA
- Department of Medicine, G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS 39216, USA
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Pikilidou MI, Lasaridis AN, Sarafidis PA, Befani CD, Koliakos GG, Tziolas IM, Kazakos KA, Yovos JG, Nilsson PM. Insulin sensitivity increase after calcium supplementation and change in intraplatelet calcium and sodium-hydrogen exchange in hypertensive patients with Type 2 diabetes. Diabet Med 2009; 26:211-9. [PMID: 19317814 DOI: 10.1111/j.1464-5491.2009.02673.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS To investigate the effect of oral calcium (Ca(2+)) supplementation on insulin sensitivity measured by the euglycaemic hyperinsulinaemic clamp, intraplatelet cationic concentration of Ca(2+) ([Ca(2+)](i)) and the transmembrane sodium-hydrogen exchanger (NHE) activity in erythrocytes in subjects with Type 2 diabetes and hypertension. PATIENTS AND METHODS In this parallel randomized controlled single-blinded trial, 31 patients were allocated to receive either 1500 mg of Ca(2+) orally, daily (n = 15) or no treatment (n = 16) for 8 weeks. At baseline and at the end of the 8-week period insulin sensitivity, [Ca(2+)](i) and the first isoform of NHE (NHE-1) activity were measured. RESULTS At the end of the study, subjects who received Ca(2+) supplementation showed higher insulin sensitivity (Delta M-value 0.32 +/- 0.5 mmol/min P < 0.05) and lower [Ca(2+)](i) (125.0 +/- 24.7 to 80.4 +/- 10.6 nmol/l, P < 0.05, mean +/- sem) and NHE-1 activity (79.5 +/- 10.0 to 52.1 +/- 6.4 mmol Na/l red cell/h, P < 0.05). None of the above parameters were changed in the control group. Simple regression analysis demonstrated the change in [Ca(2+)](i) significantly determined insulin sensitivity change (beta = -0.36, P < 0.05). CONCLUSIONS/INTERPRETATION Oral Ca(2+) supplementation improves insulin sensitivity in patients with Type 2 diabetes and hypertension. These changes are likely to be mediated by changes in intracellular ionic Ca(2+). NHE-1 activity was also reduced after Ca(2+) supplementation but its role in insulin sensitivity requires further investigation.
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Affiliation(s)
- M I Pikilidou
- 1st Department of Internal Medicine, Aristotle University of Thessaloniki, AHEPA Hospital, Thessaloniki, Greece.
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Hagström E, Hellman P, Lundgren E, Lind L, Arnlöv J. Serum calcium is independently associated with insulin sensitivity measured with euglycaemic-hyperinsulinaemic clamp in a community-based cohort. Diabetologia 2007; 50:317-24. [PMID: 17180664 DOI: 10.1007/s00125-006-0532-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 09/17/2006] [Indexed: 10/23/2022]
Abstract
AIMS/HYPOTHESIS Diabetes mellitus type 2 is associated with altered calcium metabolism. Moreover, in diseases with supranormal serum calcium levels, such as primary hyperparathyroidism, the prevalence of diabetes is increased. Relatively little is known about the relationship between serum calcium concentration and the underlying causes of diabetes-insulin resistance and defective insulin secretion-in the normocalcaemic general population. MATERIALS AND METHODS We investigated associations between serum calcium concentration and insulin sensitivity and secretion in a population-based cohort of elderly men (Uppsala Longitudinal Study of Adult Men, n = 961). Insulin sensitivity index (M/I; glucose disposal rate [M] divided by mean insulin concentration [I]) was assessed using euglycaemic-hyperinsulinaemic clamp, and insulin secretion was estimated from the early insulin response (EIR) during an OGTT. RESULTS In a multivariable linear regression model adjusting for BMI, physical activity, smoking, consumption of tea, alcohol, coffee and dietary calcium, serum phosphate and serum creatinine, 1 SD increase in serum calcium was associated with 0.17 mg kg(-1) min(-1) (mU/l)(-1) x 100 (0.024 mg kg(-1) min(-1) [pmol/l](-1) x 100) decrease in M/I (p = 0.01). The results remained robust in individuals with normal fasting glucose, normal glucose tolerance and serum calcium within the normal range (n = 413, regression coefficient for 1 SD increase -0.45, p = 0.001). Serum calcium was not associated with EIR. Dietary intake of calcium was not independently associated with insulin sensitivity or EIR. CONCLUSION/INTERPRETATION Our data support the notion that endogenous calcium may be involved early in the development of diabetes and that this effect is mediated mainly through effects on insulin sensitivity rather than defective insulin secretion. Dietary intake of calcium does not seem to influence insulin sensitivity.
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Affiliation(s)
- E Hagström
- Department of Surgical Sciences, Uppsala University, SE-751 85, Uppsala, Sweden.
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McCarty MF. PKC-mediated modulation of L-type calcium channels may contribute to fat-induced insulin resistance. Med Hypotheses 2006; 66:824-31. [PMID: 16307847 DOI: 10.1016/j.mehy.2004.08.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Accepted: 08/27/2004] [Indexed: 01/01/2023]
Abstract
Increased intracellular free calcium [Ca2+]i has been noted in adipocytes, platelets, and leukocytes of subjects with insulin resistance syndrome or allied disorders. In rodent studies, measures which increase [Ca2+]i in adipocytes and skeletal muscle are associated with impaired insulin signaling, attributable at least in part to diminished ability of insulin to activate phosphoserine phosphatase-1 (PP-1). In fat-fed insulin resistant rats, pre-treatment with a drug that selectively chelates intracellular calcium eliminates about half of the decrement in insulin-stimulated glucose uptake induced by fat feeding; since this chelator does not influence the insulin sensitivity of chow-fed rats, it is reasonable to suspect that fat feeding boosts [Ca2+]i in skeletal muscle, and that this effect is partially responsible for the associated reduction in insulin sensitivity. Clinical insulin resistance is associated with increased levels of triglycerides and other fatty acid metabolites in muscle fibers; this can give rise to diacylglycerol-mediated activation of PKC, which in turn compromises insulin signaling by triggering kinase cascades that phosphorylate IRS-1 on key serine residues. Yet there is also evidence that, in skeletal muscle, PKC activity up-regulates the function of L-type calcium channels, increasing their maximal conductance while left-shifting their voltage dependence. Thus, the PKC activation associated with fat overexposure might be expected to boost basal [Ca2+]i in skeletal muscle, potentially impeding insulin-mediated activation of PP-1. This hypothesis is consistent with several clinical studies demonstrating that long-acting inhibitors of L-type calcium channels can improve insulin sensitivity in overweight hypertensives; it should be readily testable in rodent models of fat-induced insulin resistance. Since parathyroid hormone can act on adipocytes and muscle to boost [Ca2+]i, mild secondary hyperparathyroidism associated with low calcium intakes and poor vitamin D status may contribute to insulin resistance, consistent with certain clinical and epidemiological findings. Magnesium, often thought of as a mild calcium antagonist, appears to have favorable effects on insulin sensitivity and risk for diabetes, and recent evidence indicates that increases of intracellular magnesium within the physiological range can diminish calcium influx through phosphorylated L-type calcium channels. It will be of interest to determine whether calcium antagonism does indeed underlie the favorable influence of good magnesium status on insulin function. A report that chromium picolinate can induce the plasmalemmal Ca2+-ATPase in smooth muscle cells, raises the possibility that modulation of calcium transport might play a role in the insulin-sensitizing efficacy of bioactive chromium.
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Affiliation(s)
- Mark F McCarty
- Natural Alternatives International, 1185 Linda Vista Dr., San Marcos, CA 92078, USA.
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Wiernsperger NF. Is non-insulin dependent glucose uptake a therapeutic alternative? Part 1: physiology, mechanisms and role of non insulin-dependent glucose uptake in type 2 diabetes. DIABETES & METABOLISM 2005; 31:415-26. [PMID: 16357785 DOI: 10.1016/s1262-3636(07)70212-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Several decades of research for treating type 2 diabetes have yielded new drugs but the actual experience with the available oral antidiabetic compounds clearly shows that therapeutic needs are not matched. This highlights the urgent need for exploring other pathways. All cell types have the capacity to take up glucose independently of insulin, whereby basal but also hyperglycaemia-promoted glucose supply is ensured. Although poorly explored, insulin-independent glucose uptake might nevertheless represent a therapeutic target, as an alternative to the clear limits of actual drug treatments. This review not only critically examines some major pathways not requiring insulin (although they may be influenced by the hormone) but importantly, this analysis extends to the clinical applicability of these potential therapeutic principles by also considering their predictable tolerability for long-term therapy. In particular vascular safety (the ultimate problem linked with diabetes) will be envisaged because of the ubiquitous distribution of glucose transporters and some linked mechanisms. Several mechanisms can be identified which do not require insulin for their functioning. The first part of this review deals with the description, the regulation and the limits of some mechanisms representing potential pharmacological targets capable of having a highly significant impact on glucose uptake. These selected topics are: a) unmasking and/or activation of glucose transporters in cell plasma membranes, b) insulin mimetics acting at postreceptor level, c) activation of AMPK, d) increasing nitric oxide and e) increasing glucose-6P and glycogen stores.
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Affiliation(s)
- N F Wiernsperger
- INSERM UMR 585, Bâtiment Louis Pasteur, INSA Lyon, Cedex, France.
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McCarty MF. Magnesium may mediate the favorable impact of whole grains on insulin sensitivity by acting as a mild calcium antagonist. Med Hypotheses 2005; 64:619-27. [PMID: 15617878 DOI: 10.1016/j.mehy.2003.10.034] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Accepted: 10/17/2003] [Indexed: 12/15/2022]
Abstract
Recent epidemiology has linked high consumption of whole grains with reduced risk for diabetes, coronary disease, stroke, and various types of cancer; there is reason to suspect that improved insulin sensitivity is largely responsible for this protection. This phenomenon may be partially explained by the lower glycemic indices of some whole grain food products in comparison to their fiber-depleted analogs. Nonetheless, the fact that whole wheat flour promotes insulin sensitivity relative to white flour--and yet has a near-identical glycemic index--suggests that certain nutrients or phytochemicals in whole wheat, depleted by the refining process, promote preservation of insulin sensitivity. Magnesium is a likely candidate in this regard; magnesium deficiency promotes insulin resistance in rodents and in humans, whereas supplemental magnesium has been found to prevent type 2 diabetes in rodent models of this syndrome, and to improve the insulin sensitivity of elderly or diabetic humans. Magnesium-rich diets as well as above-average serum magnesium are associated with reduced diabetes risk in prospective epidemiology, and with greater insulin sensitivity in cross-sectional studies; moreover, other types of magnesium-rich foods--dairy products, legumes, and nuts--have been linked to decreased diabetes risk in prospective studies. The biochemical role of magnesium in support of insulin function is still poorly understood. In light of evidence that magnesium can function as a mild natural calcium antagonist, it is interesting to note suggestive evidence that increases in intracellular free calcium may compromise the insulin responsiveness of adipocytes and skeletal muscle, and may indeed play a pathogenic role in the insulin resistance syndrome. Thus, it is proposed that some or all of the favorable impact of good magnesium status on insulin function may reflect antagonism of the induction or effects of increased intracellular free calcium. Further research concerning the potential health benefits of long-term magnesium supplementation is clearly warranted. These considerations, however, should not detract from efforts to better inform the public regarding the strong desirability of choosing whole grain products in preference to refined grains.
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Affiliation(s)
- Mark F McCarty
- Pantox Laboratories, 4622 Santa Fe Street, San Diego, CA 92109, USA.
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38
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Cammisotto PG, Bukowiecki LJ. Role of calcium in the secretion of leptin from white adipocytes. Am J Physiol Regul Integr Comp Physiol 2004; 287:R1380-6. [PMID: 15331383 DOI: 10.1152/ajpregu.00368.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mechanism by which calcium regulates leptin secretion was studied in adipocytes isolated from rat white adipose tissue. Incubation of adipocytes in a medium containing glucose, but no calcium, markedly inhibited insulin-stimulated leptin secretion (ISLS) and synthesis, without affecting basal leptin secretion or lipolysis. However, when pyruvate was used as a substrate, ISLS was insensitive to the absence of calcium. Likewise, the stimulatory effects of insulin were completely prevented by phloretin, cytochalasin B, and W-13 (3 agents that interfere with early steps of glucose metabolism) in the presence of glucose, but not in the presence of pyruvate. Thus calcium appears to be specifically required for glucose utilization. On the other hand,45Ca uptake and leptin secretion were not affected by insulin or by inhibitors of L-type calcium channels. However, agents increasing plasma membrane permeability to calcium (high calcium concentrations, A-23187, and ATP) increased45Ca uptake and concomitantly inhibited ISLS. Similarly, release of endogenous calcium stores by thapsigargin inhibited ISLS in a dose-dependent manner. ATP, A-23187, calcium, and thapsigargin inhibited ISLS, even in the presence of pyruvate. These results show that 1) extracellular calcium is necessary for ISLS, mainly by affecting glucose uptake, 2) insulin does not affect extracellular calcium uptake, and 3) increasing cytosolic calcium by stimulating its uptake or its release from endogenous stores inhibits ISLS at a level independent of glucose metabolism. Thus calcium regulates leptin secretion from adipocytes in a manner that is markedly different from its role in the exocytosis of many other polypeptidic hormones.
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Affiliation(s)
- Philippe G Cammisotto
- Faculty of Medicine, Department of Anatomy and Physiology, Laval University, Quebec, Canada G1K 7P4
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39
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McCarty MF. Elevated sympathetic activity may promote insulin resistance syndrome by activating alpha-1 adrenergic receptors on adipocytes. Med Hypotheses 2004; 62:830-8. [PMID: 15082116 DOI: 10.1016/j.mehy.2003.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2003] [Accepted: 11/11/2003] [Indexed: 11/19/2022]
Abstract
An excess of free intracellular calcium can reduce the efficiency of insulin-mediated glucose transport by blocking the dephosphorylation of GLUT-4. Classical isoforms of protein kinase C (PKC) can interfere with insulin signalling via serine phosphorylation of IRS-1 and the insulin receptor. Parathyroid hormone (PTH), by activating phospholipase C-beta in adipocytes, can promote a sustained increase in intracellular free calcium in these cells, while also activating classical PKCs. This may rationalize the fact that insulin resistance is a typical feature of hyperparathyroidism, as well as epidemiological evidence that regular ingestion of dairy products or of ethanol--which down-regulates PTH secretion--reduces risk for insulin resistance syndrome and diabetes. Alpha-1 adrenergic receptors of adipocytes--like PTH receptors--also activate phospholipase C-beta, and thus have an effect analogous to PTH on intracellular free calcium and PKC activity in adipocytes. This suggests that, via activation of alpha-1 adrenergic receptors, increased sympathetic activity in adipose tissue may promote insulin resistance syndrome. In fact, measures which provoke increased sympathetic output--such as diuretic use and severe salt restriction--are known to compromise insulin sensitivity, whereas alpha-1 antagonist drugs, as well as drugs that act centrally to suppress sympathetic activity, typically have a favorable effect on insulin function. When insulin resistance syndrome is associated with elevated sympathetic activity--for example, in hypertensives who are obese or on diuretic therapy--measures which down-regulate sympathetic activity, or, more specifically, alpha-1 adrenergic activity, may be warranted. These include centrally acting imidazoline analogs (moxonidine, rilmenidine) and alpha-1 antagonists (doxazosin, prazosin). Taurine and high-dose pyridoxine may represent practical nutritional strategies for moderating elevated sympathetic activity, and exercise training and low-insulin-response diets may be useful in this regard as well.
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Affiliation(s)
- Mark F McCarty
- Pantox Laboratories, 4622 Santa Fe St., San Diego, CA 29109, USA.
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40
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McCarty MF. A moderately low phosphate intake may provide health benefits analogous to those conferred by UV light - a further advantage of vegan diets. Med Hypotheses 2004; 61:543-60. [PMID: 14592785 DOI: 10.1016/s0306-9877(03)00228-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Although exposure to ultraviolet light is often viewed as pathogenic owing to its role in the genesis of skin cancer and skin aging, there is growing epidemiological evidence that such exposure may decrease risk for a number of more serious cancers, may have a favorable impact on blood pressure and vascular health, and may help to prevent certain autoimmune disorders - in addition to its well-known influence on bone density. Most likely, these health benefits are reflective of improved vitamin D status. Increased synthesis or intake of vitamin D can be expected to down-regulate parathyroid hormone (PTH), and to increase autocrine synthesis of its active metabolite calcitriol in certain tissues; these effects, in turn, may impact cancer risk, vascular health, immune regulation, and bone density through a variety of mechanisms. Presumably, a truly adequate supplemental intake of vitamin D - manyfold higher than the grossly inadequate current RDA - could replicate the benefits of optimal UV exposure, without however damaging the skin. Diets moderately low in bioavailable phosphate - like many vegan diets - might be expected to have a complementary impact on disease risks, inasmuch as serum phosphate suppresses renal calcitriol synthesis while up-regulating that of PTH. A proviso is that the impact of dietary phosphorus on bone health is more equivocal than that of vitamin D. Increased intakes of calcium, on the other hand, down-regulate the production of both PTH and calcitriol - the latter effect may explain why the impact of dietary calcium on cancer risk (excepting colon cancer), hypertension, and autoimmunity is not clearly positive. An overview suggests that a vegan diet supplemented with high-dose vitamin D should increase both systemic and autocrine calcitriol production while suppressing PTH secretion, and thus should represent a highly effective way to achieve the wide-ranging health protection conferred by optimal UV exposure.
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Affiliation(s)
- M F McCarty
- Pantox Laboratories, San Diego, CA 92109, USA.
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41
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McCarty MF, Thomas CA. PTH excess may promote weight gain by impeding catecholamine-induced lipolysis-implications for the impact of calcium, vitamin D, and alcohol on body weight. Med Hypotheses 2004; 61:535-42. [PMID: 14592784 DOI: 10.1016/s0306-9877(03)00227-5] [Citation(s) in RCA: 207] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Increased free intracellular calcium ([Ca(2+)](i)) in adipocytes blunts the lipolytic response to catecholamines by activating phosphodiesterase 3B - the same enzyme that mediates the antilipolytic effect of insulin - while also compromising the efficiency of insulin-stimulated glucose uptake. Physiological increases in parathyroid hormone (PTH) have been shown to increase [Ca(2+)](i) in adipocytes. These considerations may rationalize recent evidence that high dietary intakes of calcium and/or dairy products may reduce risk for obesity, diabetes, and insulin-resistance syndrome, and they predict that other dietary measures which down-regulate PTH - such as good vitamin D status, and moderation in phosphate and salt intakes - may likewise be beneficial in these respects. Consistent with this position are reports that body weight is elevated in elderly subjects with both primary and secondary hyperparathyroidism; furthermore, insulin resistance is a well-known complication of both forms of hyperparathyroidism. The fact that regular alcohol consumption is associated with decreased PTH secretion may help to explain why moderate drinkers are less prone to insulin resistance, diabetes, and - in women - obesity. Down-regulation of PTH cannot be expected to promote dramatic weight loss, but in the long-term it may lessen risk for significant weight gain and diabetes, and conceivably may potentiate the fat loss achievable with caloric restriction and/or exercise.
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Affiliation(s)
- M F McCarty
- Pantox Laboratories, San Diego, CA 92109, USA.
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Wang Y, Tonouchi M, Miskovic D, Hatta H, Bonen A. T3 increases lactate transport and the expression of MCT4, but not MCT1, in rat skeletal muscle. Am J Physiol Endocrinol Metab 2003; 285:E622-8. [PMID: 12900382 DOI: 10.1152/ajpendo.00069.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Triiodothyronine (T3) regulates the expression of genes involved in muscle metabolism. Therefore, we examined the effects of a 7-day T3 treatment on the monocarboxylate transporters (MCT)1 and MCT4 in heart and in red (RG) and white gastrocnemius muscle (WG). We also examined rates of lactate transport into giant sarcolemmal vesicles and the plasmalemmal MCT1 and MCT4 in these vesicles. Ingestion of T3 markedly increased circulating serum T3 (P < 0.05) and reduced weight gain (P < 0.05). T3 upregulated MCT1 mRNA (RG +77, WG +49, heart +114%, P < 0.05) and MCT4 mRNA (RG +300, WG +40%). However, only MCT4 protein expression was increased (RG +43, WG +49%), not MCT1 protein expression. No changes in MCT1 protein were observed in any tissue. T3 treatment doubled the rate of lactate transport when vesicles were exposed to 1 mM lactate (P < 0.05). However, plasmalemmal MCT4 was only modestly increased (+13%, P < 0.05). We conclude that T3 1) regulates MCT4, but not MCT1, protein expression and 2) increases lactate transport rates. This latter effect is difficult to explain by the modest changes in plasmalemmal MCT4. We speculate that either the activity of sarcolemmal MCTs has been altered or else other MCTs in muscle may have been upregulated.
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Affiliation(s)
- Yuxiang Wang
- Department of Kinesiology, University of Waterloo, Ontario, Canada
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Michelle Furtado L, Poon V, Klip A. GLUT4 activation: thoughts on possible mechanisms. ACTA PHYSIOLOGICA SCANDINAVICA 2003; 178:287-96. [PMID: 12864733 DOI: 10.1046/j.1365-201x.2003.01160.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A family of facilitative glucose transporters or GLUTs mediates glucose uptake by cells and tissues. The glucose transporter isoform GLUT4, which is the predominant isoform expressed in mature muscle and fat tissues, is primarily responsible for the increase in glucose uptake in response to insulin stimulation. Recent work in our laboratory suggests that there are two divergent responses initiated by insulin stimulation. The first response involves the recruitment of GLUT4 transporters from intracellular reserves and their subsequent insertion into the plasma membrane. The second pathway results in an increase in the intrinsic activity of the transporters. This review will discuss evidence supporting the divergence of the two pathways regulating glucose uptake and, in particular, evidence for the increased intrinsic activity of GLUT4 in response to insulin stimulation. Inhibitors of p38 mitogen-activated protein kinase (MAPK) affected only the arm leading to the insulin-stimulated activation of GLUT4. This implicates p38 MAPK involvement in the regulation of this pathway. There is further evidence that p38 MAPK is itself recruited to the plasma membrane. The role of the phosphorylation state of the glucose transporter in response to insulin stimulation has been studied and indicates that, contrary to what might be predicted, there is actually a decrease in its phosphorylation at the plasma membrane in response to insulin. The relationship of this change to glucose uptake remains to be established. Other possible mechanisms regulating GLUT4 activity include binding of (+) or (-) modulators of its function.
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Affiliation(s)
- L Michelle Furtado
- Programme in Cell Biology, The Hospital for Sick Children, Toronto, Canada
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44
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Furtado LM, Somwar R, Sweeney G, Niu W, Klip A. Activation of the glucose transporter GLUT4 by insulin. Biochem Cell Biol 2003; 80:569-78. [PMID: 12440698 DOI: 10.1139/o02-156] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The transport of glucose into cells and tissues is a highly regulated process, mediated by a family of facilitative glucose transporters (GLUTs). Insulin-stimulated glucose uptake is primarily mediated by the transporter isoform GLUT4, which is predominantly expressed in mature skeletal muscle and fat tissues. Our recent work suggests that two separate pathways are initiated in response to insulin: (i) to recruit transporters to the cell surface from intracellular pools and (ii) to increase the intrinsic activity of the transporters. These pathways are differentially inhibited by wortmannin, demonstrating that the two pathways do not operate in series. Conversely, inhibitors of p38 mitogen-activated protein kinase (MAPK) imply that p38 MAPK is involved only in the regulation of the pathway leading to the insulin-stimulated activation of GLUT4. This review discusses the evidence for the divergence of GLUT4 translocation and activity and proposed mechanisms for the regulation of GLUT4.
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Affiliation(s)
- L Michelle Furtado
- Programme in Cell Biology, Hospital for Sick Children, University of Toronto, ON, Canada
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45
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Johansson A, Holmgren S. Ca2+-recruitment in tachykinin-induced contractions of gut smooth muscle from African clawed frog, Xenopus laevis and rainbow trout, Oncorhynchus mykiss. Gen Comp Endocrinol 2003; 131:185-91. [PMID: 12679095 DOI: 10.1016/s0016-6480(03)00006-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Changes in intracellular Ca(2+) concentration control many essential cellular functions like the contraction of smooth muscle cells. The aim of this study was to investigate if the tachykinin substance P (SP) engages external Ca(2+)-sources, internal Ca(2+)-sources, or both in the contraction of the gastrointestinal smooth muscle of rainbow trout (Oncorhynchus mykiss) and the African clawed frog (Xenopus laevis). Strip preparations made of either longitudinal smooth muscle of proximal intestine or circular smooth muscle of cardiac stomach were mounted in organ baths and the tension was recorded via force transducers. Ca(2+)-free Ringer's solution containing the Ca(2+) chelating agent EGTA (2mM) abolished all spontaneous contractions. Exposure to SP in Ca(2+)-free solution decreased the response. Preparations were also treated with the Ca(2+)-ATPase inhibitor thapsigargin (10 microM) during 30 min. Thapsigargin reduced the effect of SP on intestinal longitudinal smooth muscle in rainbow trout and on stomach circular smooth muscle in the African clawed frog and to a less extent in the intestinal longitudinal smooth muscle. The results show that external Ca(2+) is of great importance, but is not the only source of Ca(2+) recruitment in SP-activation of gastrointestinal smooth muscle in rainbow trout and the African clawed frog.
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Affiliation(s)
- Agot Johansson
- Department of Zoophysiology, University of Göteborg, Box 463, SE-405 30 Göteborg, Sweden.
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46
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Heininger K. The cerebral glucose-fatty acid cycle: evolutionary roots, regulation, and (patho)physiological importance. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 51:103-58. [PMID: 12420358 DOI: 10.1016/s0074-7742(02)51004-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Kurt Heininger
- Department of Neurology, Heinrich Heine University, D-40597 Düsseldorf, Germany
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47
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Tonouchi M, Hatta H, Bonen A. Muscle contraction increases lactate transport while reducing sarcolemmal MCT4, but not MCT1. Am J Physiol Endocrinol Metab 2002; 282:E1062-9. [PMID: 11934671 DOI: 10.1152/ajpendo.00358.2001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rates of lactate uptake into giant sarcolemmal vesicles were determined in vesicles collected from rat muscles at rest and immediately after 10 min of intense muscle contraction. This contraction period reduced muscle glycogen rapidly by 37-82% in all muscles examined (P < 0.05) except the soleus muscle (no change P > 0.05). At an external lactate concentration of 1 mM lactate, uptake into giant sarcolemmal vesicles was not altered (P > 0.05), whereas at an external lactate concentration of 20 mM, the rate of lactate uptake was increased by 64% (P < 0.05). Concomitantly, the plasma membrane content of monocarboxylate transporter (MCT)1 was reduced slightly (-10%, P < 0.05), and the plasma membrane content of MCT4 was reduced further (-25%, P < 0.05). In additional studies, the 10-min contraction period increased the plasma membrane GLUT4 (P < 0.05) while again reducing MCT4 (-20%, P < 0.05) but not MCT1 (P > 0.05). These studies have shown that intense muscle contraction can increase the initial rates of lactate uptake, but only when the external lactate concentrations are high (20 mM). We speculate that muscle contraction increases the intrinsic activity of the plasma membrane MCTs, because the increase in lactate uptake occurred while plasma membrane MCT4 was decreased and plasma membrane MCT1 was reduced only minimally, or not at all.
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Affiliation(s)
- Mio Tonouchi
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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48
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Klip A, Marette A. Regulation of Glucose Transporters by Insulin and Exercise: Cellular Effects and Implications for Diabetes. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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49
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Heininger K. A unifying hypothesis of Alzheimer's disease. IV. Causation and sequence of events. Rev Neurosci 2001; 11 Spec No:213-328. [PMID: 11065271 DOI: 10.1515/revneuro.2000.11.s1.213] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Contrary to common concepts, the brain in Alzheimer's disease (AD) does not follow a suicide but a rescue program. Widely shared features of metabolism in starvation, hibernation and various conditions of energy deprivation, e.g. ischemia, allow the definition of a deprivation syndrome which is a phylogenetically conserved adaptive response to energetic stress. It is characterized by hypometabolism, oxidative stress and adjustments of the glucose-fatty acid cycle. Cumulative evidence suggests that the brain in aging and AD actively adapts to the progressive fuel deprivation. The counterregulatory mechanisms aim to preserve glucose for anabolic needs and promote the oxidative utilization of ketone bodies. The agent mediating the metabolic switch is soluble Abeta which inhibits glucose utilization and stimulates ketone body utilization at various levels. These processes, which are initiated during normal aging, include inhibition of pro-glycolytic neurohormones, cholinergic transmission, and pyruvate dehydrogenase, the key transmitter and effector systems regulating glucose metabolism. Hormonal and effector systems which promote ketone body utilization, such as glucocorticosteroid and galanin activity, GABAergic transmission, nitric oxide, lipid transport, Ca2+ elevation, and ketone body metabolizing enzymes, are enhanced. A multitude of risk factors feed into this pathophysiological cascade at a variety of levels. Taking into account its pleiotropic regulatory actions in the deprivation response, a new name for Abeta is suggested: deprivin. On the other hand, cumulative evidence, taken together compelling, suggests that senile plaques are the dump rather than the driving force of AD. Moreover, the neurotoxic action of fibrillar Abeta is a likely in vitro artifact but does not contribute significantly to the in vivo pathophysiological events. This archaic program, conserved from bacteria to man, aims to ensure the survival of a deprived organism and controls such divergent processes as sporulation, hibernation, aging and aging-related diseases. In contrast to the immature brain, ketone body utilization of the aged brain is no longer sufficient to meet the energetic demands and is later supplemented by lactate, thus recapitulating in reverse order the sequential fuel utilization of the immature brain. The transduction pathways which operate to switch metabolism also convey the programming and balancing of the de-/redifferentiation/apoptosis cell cycle decisions. This encompasses the reiteration of developmental processes such as transcription factor activation, tau hyperphosphorylation, and establishment of growth factor independence by means of Ca2+ set point shift. Thus, the increasing energetic insufficiency results in the progressive centralization of metabolic activity to the neuronal soma, leading to pruning of the axonal/dendritic trees, loss of neuronal polarity, downregulation of neuronal plasticity and, eventually, depending on the Ca2+ -energy-redox homeostasis, degeneration of vulnerable neurons. Finally, it is outlined that genetic (e.g. Down's syndrome, APP and presenilin mutations and apoE4) and environmental risk factors represent progeroid factors which accelerate the aging process and precipitate the manifestation of AD as a progeroid systemic disease. Aging and AD are related to each other by threshold phenomena, corresponding to stage 2, the stage of resistance, and stage 3, exhaustion, of a metabolic stress response.
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Affiliation(s)
- K Heininger
- Department of Neurology, Heinrich Heine University, Düsseldorf, Germany
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50
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Chen Z, Eggerman TL, Potosky D, Arborati M, Patterson AP. Calcium increases apolipoprotein B mRNA editing. Biochem Biophys Res Commun 2000; 277:221-7. [PMID: 11027667 DOI: 10.1006/bbrc.2000.3668] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ApoB-100 and apoB-48 are major components of chylomicrons, very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL). The two proteins are generated from a single apoB mRNA by apoB mRNA editing which induces an in-frame stop codon in apoB mRNA. Apolipoprotein B (apoB) mRNA editing is an important determinant of the proportion of full-length (apoB-100) and truncated (apoB-48) proteins in total apoB metabolism. Calcium is involved in the regulation of secretion and synthesis of VLDL and apoB. In this paper, we demonstrate for the first time that the amount of edited apoB mRNA in the cultured cells Caco-2 and McA7777 is markedly increased by calcium. Increasing extracellular calcium concentration, calcium ionophore (A23187 and ionomycin) treatment, and depleting calcium stores and raising cytoplasmic calcium concentration by thapsigargin increase apoB mRNA editing up to threefold in a dose dependent manner. Calcium has no direct stimulative effect on apoB mRNA editing in an in vitro editing system. The editing increase by extracellular calcium is not related to alterations of APOBEC-1 mRNA expression. These data suggest that calcium is not only involved in the regulation of apolipoprotein metabolism but also apoB mRNA editing.
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Affiliation(s)
- Z Chen
- National Heart, Lung and Blood Institute, Bethesda, Maryland, 20892, USA
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