1
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Leibold NS, Despa F. Neuroinflammation induced by amyloid-forming pancreatic amylin: Rationale for a mechanistic hypothesis. Biophys Chem 2024; 310:107252. [PMID: 38663120 DOI: 10.1016/j.bpc.2024.107252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 04/18/2024] [Accepted: 04/21/2024] [Indexed: 05/15/2024]
Abstract
Amylin is a systemic neuroendocrine hormone co-expressed and co-secreted with insulin by pancreatic β-cells. In persons with thype-2 diabetes, amylin forms pancreatic amyloid triggering inflammasome and interleukin-1β signaling and inducing β-cell apoptosis. Here, we summarize recent progress in understanding the potential link between amyloid-forming pancreatic amylin and Alzheimer's disease (AD). Clinical data describing amylin pathology in AD alongside mechanistic studies in animals are reviewed. Data from multiple research teams indicate higher amylin concentrations are associated with increased frequency of cognitive impairment and amylin co-aggregates with β-amyloid in AD-type dementia. Evidence from rodent models further suggests cerebrovascular amylin accumulation as a causative factor underlying neurological deficits. Analysis of relevant literature suggests that modulating the amylin-interleukin-1β pathway may provide an approach for counteracting neuroinflammation in AD.
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Affiliation(s)
- Noah S Leibold
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA.
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2
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Das S, Verma N, Goldstein LB, Despa F. Skin capillary amylin deposition resembles brain amylin vasculopathy in rats. J Stroke Cerebrovasc Dis 2023; 32:107300. [PMID: 37572602 DOI: 10.1016/j.jstrokecerebrovasdis.2023.107300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 08/04/2023] [Accepted: 08/06/2023] [Indexed: 08/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Human amylin is a 37 amino-acid pancreatic peptide that forms neuro-toxic aggregates that deposit in the endothelium of brain capillaries of patients with diabetes, potentially contributing to cerebral small vessel ischemic injury. Pathogenic amylin also deposits in the capillary endothelium in other organs, including the skin. The aim of this study was to test the hypothesis that skin capillary amylin deposition correlates with cerebral small vessel amylin deposition, potentially providing a clinically useful marker of cerebral amylin deposition. METHODS Immunohistochemistry (IHC) was performed for human amylin and collagen IV in brain and skin sections of rats (age 15-16 months) with pancreatic overexpression of amyloidogenic human amylin polypeptide (HIP rats), and control rats (Wild type; WT; rats that express non-amyloidogenic rat amylin) using antibodies binding amylin (n = 5 male and 5 female rats for each group) and antibodies binding Hypoxia inducing factor (HIF)-1α and HIF-2α (n = 3 for each group). The reactive amylin-aldehyde 4-hydroxynonenal (4-HNE) adduct was measured in skin homogenates. (n = 4 for each group) RESULTS: Brain capillaries isolated from HIP rats had higher amylin content compared to WT rats using Western blot with anti-amylin antibody (p = 0.0010). The HIF-1α and HIF-2α immunoreactivity signals in skin from HIP and WT rats were similar (p = 0.2 for HIF-1 α, and p = 0.75 for HIF-2α). Amylin-4HNE adduct formation was higher in HIP rats compared to WT rats (p = 0.0014). There was phenotypic similarity between brain and skin capillary amylin based on co-staining for human amylin and collagen IV in both HIP and WT rats. CONCLUSION Skin and brain capillary amylin deposition are similar providing evidence that a skin biopsy might be providing a potential biomarker for diabetes-associated intracranial vasculopathy.
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Affiliation(s)
- Saurav Das
- Department of Neurology, University of Kentucky, United States.
| | - Nirmal Verma
- Pharmacology and Nutritional Sciences, University of Kentucky, United States
| | - Larry B Goldstein
- Department of Neurology, University of Kentucky, United States. https://twitter.com/https://twitter.com/LBGoldsteinMD
| | - Florin Despa
- Pharmacology and Nutritional Sciences, University of Kentucky, United States. https://twitter.com/https://twitter.com/UKyNeuroscience
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3
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Velmurugan S, Liu T, Chen KC, Despa F, O'Rourke B, Despa S. Distinct Effects of Mitochondrial Na +/Ca 2+ Exchanger Inhibition and Ca 2+ Uniporter Activation on Ca 2+ Sparks and Arrhythmogenesis in Diabetic Rats. J Am Heart Assoc 2023; 12:e029997. [PMID: 37421267 PMCID: PMC10382117 DOI: 10.1161/jaha.123.029997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 05/26/2023] [Indexed: 07/10/2023]
Abstract
Background Mitochondrial dysfunction contributes to the cardiac remodeling triggered by type 2 diabetes (T2D). Mitochondrial Ca2+ concentration ([Ca2+]m) modulates the oxidative state and cytosolic Ca2+ regulation. Thus, we investigated how T2D affects mitochondrial Ca2+ fluxes, the downstream consequences on myocyte function, and the effects of normalizing mitochondrial Ca2+ transport. Methods and Results We compared myocytes/hearts from transgenic rats with late-onset T2D (rats that develop late-onset T2D due to heterozygous expression of human amylin in the pancreatic β-cells [HIP] model) and their nondiabetic wild-type (WT) littermates. [Ca2+]m was significantly lower in myocytes from diabetic HIP rats compared with WT cells. Ca2+ extrusion through the mitochondrial Na+/Ca2+ exchanger (mitoNCX) was elevated in HIP versus WT myocytes, particularly at moderate and high [Ca2+]m, while mitochondrial Ca2+ uptake was diminished. Mitochondrial Na+ concentration was comparable in WT and HIP rat myocytes and remained remarkably stable while manipulating mitoNCX activity. Lower [Ca2+]m was associated with oxidative stress, increased sarcoplasmic reticulum Ca2+ leak in the form of Ca2+ sparks, and mitochondrial dysfunction in T2D hearts. MitoNCX inhibition with CGP-37157 reduced oxidative stress, Ca2+ spark frequency, and stress-induced arrhythmias in HIP rat hearts while having no significant effect in WT rats. In contrast, activation of the mitochondrial Ca2+ uniporter with SB-202190 enhanced spontaneous sarcoplasmic reticulum Ca2+ release and had no significant effect on arrhythmias in both WT and HIP rat hearts. Conclusions [Ca2+]m is reduced in myocytes from rats with T2D due to a combination of exacerbated mitochondrial Ca2+ extrusion through mitoNCX and impaired mitochondrial Ca2+ uptake. Partial mitoNCX inhibition limits sarcoplasmic reticulum Ca2+ leak and arrhythmias in T2D hearts, whereas mitochondrial Ca2+ uniporter activation does not.
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Affiliation(s)
- Sathya Velmurugan
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Ting Liu
- Division of Cardiology, Department of MedicineThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Kuey C. Chen
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Florin Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Brian O'Rourke
- Division of Cardiology, Department of MedicineThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Sanda Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
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4
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Kotiya D, Leibold N, Verma N, Jicha GA, Goldstein LB, Despa F. Rapid, scalable assay of amylin-β amyloid co-aggregation in brain tissue and blood. J Biol Chem 2023; 299:104682. [PMID: 37030503 PMCID: PMC10192925 DOI: 10.1016/j.jbc.2023.104682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/30/2023] [Accepted: 04/01/2023] [Indexed: 04/10/2023] Open
Abstract
Islet amyloid polypeptide (amylin) secreted from the pancreas crosses from the blood to the brain parenchyma and forms cerebral mixed amylin-β amyloid (Aβ) plaques in persons with Alzheimer's disease (AD). Cerebral amylin-Aβ plaques are found in both sporadic and early-onset familial AD; however, the role of amylin-Aβ co-aggregation in potential mechanisms underlying this association remains unknown, in part due to lack of assays for detection of these complexes. Here, we report the development of an ELISA to detect amylin-Aβ hetero-oligomers in brain tissue and blood. The amylin-Aβ ELISA relies on a monoclonal anti-Aβ mid-domain antibody (detection) and a polyclonal anti-amylin antibody (capture) designed to recognize an epitope that is distinct from the high affinity amylin-Aβ binding sites. The utility of this assay is supported by the analysis of molecular amylin-Aβ codeposition in postmortem brain tissue obtained from persons with and without AD pathology. By using transgenic AD-model rats, we show that this new assay can detect circulating amylin-Aβ hetero-oligomers in the blood and is sensitive to their dissociation to monomers. This is important because therapeutic strategies to block amylin-Aβ co-aggregation could reduce or delay the development and progression of AD.
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Affiliation(s)
- Deepak Kotiya
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA; The Research Center for Healthy Metabolism, University of Kentucky, Lexington, Kentucky, USA
| | - Noah Leibold
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA; The Research Center for Healthy Metabolism, University of Kentucky, Lexington, Kentucky, USA
| | - Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA; The Research Center for Healthy Metabolism, University of Kentucky, Lexington, Kentucky, USA
| | - Gregory A Jicha
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA; Department of Neurology, University of Kentucky, Lexington, Kentucky, USA
| | - Larry B Goldstein
- Department of Neurology, University of Kentucky, Lexington, Kentucky, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA; The Research Center for Healthy Metabolism, University of Kentucky, Lexington, Kentucky, USA; Department of Neurology, University of Kentucky, Lexington, Kentucky, USA.
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5
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Despa F. Bloodborne Pancreatic Amylin, A Therapeutic Target for Alzheimer's Disease. Curr Alzheimer Res 2023; 19:CAR-EPUB-129561. [PMID: 36803745 DOI: 10.2174/1567205020666230217091540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/19/2023]
Abstract
Alzheimer Disease (AD) pathology has been linked to brain accumulation of β amyloid (Aβ) and neurofibrillary tau tangles. An intriguing question is whether targeting therapeutically factors independent of Aβ and tau pathologies could delay or even stop neurodegeneration. Amylin, a pancreatic hormone co-secreted with insulin, is believed to play a role in the central regulation of satiation and was shown to form pancreatic amyloid in persons with type-2 diabetes mellitus. Accumulating evidence demonstrates that amyloid-forming amylin secreted from the pancreas synergistically aggregates with vascular and parenchymal Aβ in the brain, in both sporadic and early-onset familial AD. Pancreatic expression of amyloid-forming human amylin in AD-model rats accelerates AD-like pathology, whereas genetically suppressed amylin secretion protects against AD effects. Thus, current data suggest a role of pancreatic amyloid-forming amylin in modifying AD; further research is required to test whether lowering circulating amylin levels early during AD pathogenesis may curb cognitive decline.
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Affiliation(s)
- Florin Despa
- University of Kentucky Pharmacology and Nutritional Sciences Lexington United States
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6
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Gopal Viswanathan V, Verma N, D. Winford E, Kotiya D, E. Radulescu L, Leibold N, C. Chen K, Despa S, A. Hill D, Muehlbauer M, R. Bain J, Despa F. Abstract 128:
In Vivo
Downregulation Of Pancreatic Amylin In Diabetic Mice Improves Recognition Memory. Stroke 2023. [DOI: 10.1161/str.54.suppl_1.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hypersecretion of amylin, a β-cell hormone that regulates satiation, is common in individuals with prediabetes and is associated with pancreatic amyloid deposition and type-2 diabetes. Evidence has emerged that increased circulating levels of amyloid-forming human amylin may potentially impair brain function. Because mouse amylin is non-amyloidogenic, we generated transgenic mice with
conditional
pancreatic expression of amyloid-forming human amylin to study how
in vivo
knockdown of human amylin expression influences brain function during the development of type-2 diabetes. Males and females were fed a high-fat diet starting at 3 months of age to induce amylin hypersecretion and glucose dysregulation. Males developed hyperglycemia at 5 months of age, whereas females showed glucose dysregulation 3-4 months later. At 5 months of age, human amylin-expressing male mice were randomly assigned to either amylin downregulation group (by peritoneal tamoxifen injection) or control group (maintained amylin expression) (n = 10/group). Two months later, we assessed brain function with the novel object recognition test and performed comparative non-targeted metabolomics and global RNA-seq analyses of hippocampal tissue. Mice with downregulated human amylin show enhanced recognition memory index (p < 0.001) and lower blood glucose levels (p < 0.001) compared to those that continued to express human amylin. This was associated with increased hippocampal levels of glycolysis metabolites, including lactic acid (p < 0.01), glucose-6-phosphate (p = 0.06), and fructose (p = 0.07). Hippocampal gene-expression patterns between the two mouse groups revealed extensive compensatory changes in gene expression related to glucose metabolism. In conclusion, amylin downregulation in diabetic mice improves systemic glucose homeostasis and memory. Molecular processes associated with improved memory involve increased hippocampal glycolytic fluxes and compensatory gene expression.
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7
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Leibold N, Kotiya D, Sheikhi L, Dornbos DL, Pahwa SS, Trout AL, Frank JA, Pennypacker KR, Goldstein LB, Despa F, Fraser JF. Abstract WP247: Amylin, A Diabetes-associated Amyloid-forming Peptide, Accumulates In Thrombi And On Red Blood Cells - A New Biomarker For Stroke? Stroke 2023. [DOI: 10.1161/str.54.suppl_1.wp247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Emergent large vessel occlusions result in severe ischemic stroke without appropriate treatment with thrombolysis and/or mechanical thrombectomy. Type-2 diabetes mellitus (T2DM) is a major risk factor in stroke, with 25% of ischemic attacks occurring in individuals with T2DM. T2DM diagnosis is also associated with poorer functional outcomes, prolonged hospitalizations, and increased risk of recurrent stroke. Amylin, a peptide co-secreted with insulin in pancreatic β-cells, is hypersecreted in T2DM and readily forms neurotoxic oligomers which deposit in brain parenchyma. Due to amylin’s role in T2DM and T2DM’s relationship to stroke, we anticipated an increased level of amylin would be deposited on red blood cells (RBCs) of stroke patients when compared to non-stroke patients. Additionally, we anticipated an increased level of amylin immunoreactivity (AIR) in clot lysates when compared to RBC lysates and plasma. Blood samples and thrombi (
n
=47) were collected from patients undergoing mechanical thrombectomies for stroke while blood samples (
n
=21) were collected from patients with non-stroke neurological conditions. Samples were lysed and assayed for total protein concentration and intensity of AIR. Amylin uptake coefficients (AUCs) demonstrating the proportionality of amylin deposited on RBCs compared to total circulating amylin were calculated. After normalizing to total protein concentration, analysis revealed a significantly increased level of AIR in stroke clots when compared to stroke and non-stroke plasma and RBC lysates (p<0.001 for each). Additionally, a significant increase (p<0.0073) in AUC was found in stroke versus non-stroke. In summary, amylin accumulates in thrombi and deposits on RBCs of stroke patients. Further research into amylin’s potential role in thrombus formation is justified. Future studies are also needed to determine if stroke severity is associated with amylin level in thrombi and if T2DM exacerbates amylin-stroke pathology.
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Affiliation(s)
- Noah Leibold
- Pharmacology & Nutritional Sciences, Univ of Kentucky, Lexington, KY
| | - Deepak Kotiya
- Pharmacology & Nutritional Sciences, Univ of Kentucky, Lexington, KY
| | | | | | | | | | | | | | | | - Florin Despa
- Pharmacology & Nutritional Sciences, Univ of Kentucky, Lexington, KY
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8
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Leibold N, Bain JR, Despa F. Type-2 Diabetes, Pancreatic Amylin, and Neuronal Metabolic Remodeling in Alzheimer's Disease. Mol Nutr Food Res 2023:e2200405. [PMID: 36708219 PMCID: PMC10374875 DOI: 10.1002/mnfr.202200405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/26/2022] [Indexed: 01/29/2023]
Abstract
Type-2 diabetes raises the risk for Alzheimer's disease (AD)-type dementia and the conversion from mild cognitive impairment to dementia, yet mechanisms connecting type-2 diabetes to AD remain largely unknown. Amylin, a pancreatic β-cell hormone co-secreted with insulin, participates in the central regulation of satiation, but also forms pancreatic amyloid in persons with type-2 diabetes and synergistically interacts with brain amyloid β (Aβ) pathology, in both sporadic and familial Alzheimer's disease (AD). Growing evidence from studies of tumor growth, together with early observations in skeletal muscle, indicates amylin as a potential trigger of cellular metabolic reprogramming. Because the blood, cerebrospinal fluid, and brain parenchyma in humans with AD have increased concentrations of amylin, amylin-mediated pathological processes in the brain may involve neuronal metabolic remodeling. This review summarizes recent progress in understanding the link between prediabetic hypersecretion of amylin and risk of neuronal metabolic remodeling and AD and suggests nutritional and medical effects of food constituents that might prevent and/or ameliorate amylin-mediated neuronal metabolic remodeling.
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Affiliation(s)
- Noah Leibold
- Department of Pharmacology and Nutritional Sciences, The University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, The University of Kentucky, Lexington, KY, USA
| | - James R. Bain
- Division of Endocrinology, Metabolism, and Nutrition, Department of Medicine, Claude D. Pepper Older Americans Independence Center, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, The University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, The University of Kentucky, Lexington, KY, USA
- Department of Neurology, The University of Kentucky, Lexington, KY, USA
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9
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Verma N, Velmurugan GV, Winford E, Coburn H, Kotiya D, Leibold N, Radulescu L, Despa S, Chen KC, Van Eldik LJ, Nelson PT, Wilcock DM, Jicha GA, Stowe AM, Goldstein LB, Powel DK, Walton JH, Navedo MF, Nystoriak MA, Murray AJ, Biessels GJ, Troakes C, Zetterberg H, Hardy J, Lashley T, Despa F. Aβ efflux impairment and inflammation linked to cerebrovascular accumulation of amyloid-forming amylin secreted from pancreas. Commun Biol 2023; 6:2. [PMID: 36596993 PMCID: PMC9810597 DOI: 10.1038/s42003-022-04398-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 12/21/2022] [Indexed: 01/04/2023] Open
Abstract
Impairment of vascular pathways of cerebral β-amyloid (Aβ) elimination contributes to Alzheimer disease (AD). Vascular damage is commonly associated with diabetes. Here we show in human tissues and AD-model rats that bloodborne islet amyloid polypeptide (amylin) secreted from the pancreas perturbs cerebral Aβ clearance. Blood amylin concentrations are higher in AD than in cognitively unaffected persons. Amyloid-forming amylin accumulates in circulating monocytes and co-deposits with Aβ within the brain microvasculature, possibly involving inflammation. In rats, pancreatic expression of amyloid-forming human amylin indeed induces cerebrovascular inflammation and amylin-Aβ co-deposits. LRP1-mediated Aβ transport across the blood-brain barrier and Aβ clearance through interstitial fluid drainage along vascular walls are impaired, as indicated by Aβ deposition in perivascular spaces. At the molecular level, cerebrovascular amylin deposits alter immune and hypoxia-related brain gene expression. These converging data from humans and laboratory animals suggest that altering bloodborne amylin could potentially reduce cerebrovascular amylin deposits and Aβ pathology.
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Affiliation(s)
- Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, University of Kentucky, Lexington, KY, USA
| | | | - Edric Winford
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
| | - Han Coburn
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Deepak Kotiya
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, University of Kentucky, Lexington, KY, USA
| | - Noah Leibold
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, University of Kentucky, Lexington, KY, USA
| | - Laura Radulescu
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, University of Kentucky, Lexington, KY, USA
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- The Research Center for Healthy Metabolism, University of Kentucky, Lexington, KY, USA
| | - Kuey C Chen
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
- UKHC Genomics Laboratory, University of Kentucky, Lexington, KY, USA
| | - Linda J Van Eldik
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Peter T Nelson
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Gregory A Jicha
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
- Department of Neurology, University of Kentucky, Lexington, KY, USA
| | - Ann M Stowe
- Department of Neurology, University of Kentucky, Lexington, KY, USA
| | | | - David K Powel
- Magnetic Resonance Imaging and Spectroscopy Center, University of Kentucky, Lexington, KY, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - Andrew J Murray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK
| | - Geert Jan Biessels
- Department of Neurology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Claire Troakes
- Basic and Clinical Neuroscience Department, King's College London, London, UK
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- UK Dementia Research Institute at UCL and Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, UK
| | - John Hardy
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- UK Dementia Research Institute at UCL and Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, UK
- Reta Lila Weston Institute, UCL Queen Square Institute of Neurology, 1 Wakefield Street, London, WC1N 1PJ, UK
- UCL Movement Disorders Centre, University College London, London, UK
- Institute for Advanced Study, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Tammaryn Lashley
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, London, UK
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA.
- The Research Center for Healthy Metabolism, University of Kentucky, Lexington, KY, USA.
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA.
- Department of Neurology, University of Kentucky, Lexington, KY, USA.
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10
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Verma N, Despa F. The association between renal accumulation of pancreatic amyloid-forming amylin and renal hypoxia. Front Endocrinol (Lausanne) 2023; 14:1104662. [PMID: 36875454 PMCID: PMC9978768 DOI: 10.3389/fendo.2023.1104662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/06/2023] [Indexed: 02/18/2023] Open
Abstract
Chronic kidney disease (CKD) is increasing worldwide and is associated with diabetic states (obesity, prediabetes and type-2 diabetes mellitus). The kidney is intrinsically susceptible to low oxygen (hypoxia) and renal hypoxia plays a vital role in the progression of CKD. Recent studies suggest an association between CKD and renal deposition of amyloid-forming amylin secreted from the pancreas. Renal accumulation of amyloid-forming amylin is associated with hypertension, mitochondrial dysfunction, increased production of reactive oxygen species (ROS) and activation of hypoxia signaling in the kidney. In this review we will discuss potential associations between renal amylin amyloid accumulation, hypertension, and mechanism of hypoxia-induced kidney dysfunction, including activation of hypoxia-inducible factors (HIFs) and mitochondrial dysfunction.
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11
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Verma N, Ly H, Despa F. Cerebrovascular accumulation of amyloid‐forming amylin secreted from the pancreas induces brain hypoxia. Alzheimers Dement 2022. [DOI: 10.1002/alz.067188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Han Ly
- University of Kentucky Lexington KY USA
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12
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Leibold NS, Kotiya D, Despa F, Sheikhi L, III DLD, Pahwa SS, Trout A, Frank JA, Pennypacker KR, Goldstein LB, Fraser JF. Amyloidogenic amylin deposits on red blood cells of stroke patients. Alzheimers Dement 2022. [DOI: 10.1002/alz.069419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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13
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Viswanathan VG, Kotiya D, Verma N, Despa F. In vivo
downregulation of pancreatic amylin improves brain function and reduces brain β amyloid pathology in APP/PS1 mice. Alzheimers Dement 2022. [DOI: 10.1002/alz.067220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Jicha GA, Goldstein LB, Wilcock DM, Despa F. Baseline blood amylin levels predict longitudinal cognitive decline in participants at risk for or with mild cognitive impairment and dementia. Alzheimers Dement 2022. [DOI: 10.1002/alz.066330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | - Donna M Wilcock
- University of Kentucky / Sanders‐Brown Center on Aging Lexington KY USA
- University of Kentucky College of Medicine Lexington KY USA
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15
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Velmurugan S, Mair H, Yin G, Despa F, Despa S. Inhibition of sodium glucose cotransporter 1 reduces arrhythmogenesis in diabetic rats. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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16
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Verma N, Srodulski S, Velmurugan S, Hoskins A, Pandey VK, Despa F, Despa S. Gestational diabetes triggers postpartum cardiac hypertrophy via activation of calcineurin/NFAT signaling. Sci Rep 2021; 11:20926. [PMID: 34686739 PMCID: PMC8536766 DOI: 10.1038/s41598-021-00422-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/12/2021] [Indexed: 01/11/2023] Open
Abstract
Population-based studies identified an association between a prior pregnancy complicated by gestational diabetes mellitus (GDM) and cardiac hypertrophy and dysfunction later in life. It is however unclear whether GDM initiates this phenotype and what are the underlying mechanisms. We addressed these questions by using female rats that express human amylin (HIP rats) as a GDM model and their wild-type (WT) littermates as the normal pregnancy model. Pregnant and two months postpartum HIP females had increased left-ventricular mass and wall thickness compared to non-pregnant HIP females, which indicates the presence of concentric hypertrophy. These parameters were unchanged in WT females during both pregnancy and postpartum periods. Hypertrophic Ca2+-dependent calcineurin/NFAT signaling was stimulated two months after giving birth in HIP females but not in the WT. In contrast, the CaMKII/HDAC hypertrophy pathway was active immediately after giving birth and returned to the baseline by two months postpartum in both WT and HIP females. Myocytes from two months postpartum HIP females exhibited slower Ca2+ transient relaxation and higher diastolic Ca2+ levels, which may explain calcineurin activation. No such effects occurred in the WT. These results suggest that a GDM-complicated pregnancy accelerates the development of pathological cardiac remodeling likely through activation of calcineurin/NFAT signaling.
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Affiliation(s)
- Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA
| | - Sarah Srodulski
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA
| | - Sathya Velmurugan
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA
| | - Amanda Hoskins
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA
| | - Vivek K Pandey
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 900 S Limestone, CTW 465, Lexington, KY, 40536, USA.
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17
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Abstract
Recent histological analyses of human brains show that small vessel-type injuries in the setting of type-2 diabetes colocalize with deposits of amylin, an amyloid-forming hormone secreted by the pancreas. Amylin inclusions are also identified in circulating red blood cells in people with type-2 diabetes and stroke or cardiovascular disease. In laboratory models of type-2 diabetes, accumulation of aggregated amylin in blood and the cerebral microvasculature induces brain microhemorrhages and reduces cerebral blood flow leading to white matter ischemia and neurological deficits. At the cellular level, aggregated amylin causes cell membrane lipid peroxidation injury, downregulation of tight junction proteins, and activation of proinflammatory signaling pathways which, in turn, induces macrophage activation and macrophage infiltration in vascular areas positive for amylin deposition. We review each step of this cascade based on experimental and clinical evidence and propose the hypothesis that systemic amylin dyshomeostasis may underlie the disparity between glycemic control and stroke risk and may be a therapeutic target to reduce the risk of small vessel ischemic stroke in patients with type-2 diabetes.
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Affiliation(s)
- Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA,Department of Neurology, University of Kentucky, Lexington, KY, USA
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18
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Ly H, Verma N, Sharma S, Kotiya D, Despa S, Abner EL, Nelson PT, Jicha GA, Wilcock DM, Goldstein LB, Guerreiro R, Brás J, Hanson AJ, Craft S, Murray AJ, Biessels GJ, Troakes C, Zetterberg H, Hardy J, Lashley T, AESG, Despa F. The association of circulating amylin with β-amyloid in familial Alzheimer's disease. Alzheimers Dement (N Y) 2021; 7:e12130. [PMID: 33521236 PMCID: PMC7816817 DOI: 10.1002/trc2.12130] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/13/2020] [Accepted: 11/25/2020] [Indexed: 01/11/2023]
Abstract
INTRODUCTION This study assessed the hypothesis that circulating human amylin (amyloid-forming) cross-seeds with amyloid beta (Aβ) in early Alzheimer's disease (AD). METHODS Evidence of amylin-AD pathology interaction was tested in brains of 31 familial AD mutation carriers and 20 cognitively unaffected individuals, in cerebrospinal fluid (CSF) (98 diseased and 117 control samples) and in genetic databases. For functional testing, we genetically manipulated amylin secretion in APP/PS1 and non-APP/PS1 rats. RESULTS Amylin-Aβ cross-seeding was identified in AD brains. High CSF amylin levels were associated with decreased CSF Aβ42 concentrations. AD risk and amylin gene are not correlated. Suppressed amylin secretion protected APP/PS1 rats against AD-associated effects. In contrast, hypersecretion or intravenous injection of human amylin in APP/PS1 rats exacerbated AD-like pathology through disruption of CSF-brain Aβ exchange and amylin-Aβ cross-seeding. DISCUSSION These findings strengthened the hypothesis of circulating amylin-AD interaction and suggest that modulation of blood amylin levels may alter Aβ-related pathology/symptoms.
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Affiliation(s)
- Han Ly
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKentuckyUSA,The Research Center for Healthy MetabolismUniversity of KentuckyLexingtonKentuckyUSA
| | - Nirmal Verma
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKentuckyUSA,The Research Center for Healthy MetabolismUniversity of KentuckyLexingtonKentuckyUSA
| | - Savita Sharma
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKentuckyUSA
| | - Deepak Kotiya
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKentuckyUSA,The Research Center for Healthy MetabolismUniversity of KentuckyLexingtonKentuckyUSA
| | - Sanda Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKentuckyUSA,The Research Center for Healthy MetabolismUniversity of KentuckyLexingtonKentuckyUSA
| | - Erin L. Abner
- Department of EpidemiologyCollege of Public HealthUniversity of KentuckyLexingtonKentuckyUSA,Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Peter T. Nelson
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA
| | - Gregory A. Jicha
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA,Department of NeurologyUniversity of KentuckyLexingtonKentuckyUSA
| | - Donna M. Wilcock
- Sanders‐Brown Center on AgingUniversity of KentuckyLexingtonKentuckyUSA,Department of PhysiologyUniversity of KentuckyLexingtonKentuckyUSA
| | | | - Rita Guerreiro
- Center for Neurodegenerative ScienceVan Andel Research InstituteGrand RapidsMichiganUSA
| | - José Brás
- Center for Neurodegenerative ScienceVan Andel Research InstituteGrand RapidsMichiganUSA
| | - Angela J. Hanson
- Memory & Brain Wellness CenterUniversity of WashingtonSeattleWashingtonUSA
| | - Suzanne Craft
- Department of Gerontology and Geriatric MedicineWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - Andrew J. Murray
- Department of PhysiologyDevelopment and NeuroscienceUniversity of CambridgeCambridgeUK
| | - Geert Jan Biessels
- Department of NeurologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Claire Troakes
- Basic and Clinical Neuroscience DepartmentKing's College LondonLondonUK
| | - Henrik Zetterberg
- Department of Psychiatry and NeurochemistryInstitute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgMölndalSweden,Clinical Neurochemistry LaboratorySahlgrenska University HospitalMölndalSweden,Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyQueen Square, LondonUK,UK Dementia Research Institute at UCL and Department of Neurodegenerative DiseaseUCL Institute of NeurologyUniversity College LondonLondonUK
| | - John Hardy
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyQueen Square, LondonUK,UK Dementia Research Institute at UCL and Department of Neurodegenerative DiseaseUCL Institute of NeurologyUniversity College LondonLondonUK,Reta Lila Weston InstituteUCL Queen Square Institute of NeurologyLondonUK,UCL Movement Disorders CentreUniversity College LondonLondonUK,Institute for Advanced StudyThe Hong Kong University of Science and TechnologyHong Kong SARChina
| | - Tammaryn Lashley
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyQueen Square, LondonUK,Queen Square Brain Bank for Neurological DisordersDepartment of Clinical and Movement NeuroscienceUCL Queen Square Institute of NeurologyLondonUK
| | - AESG
- Alzheimer's disease Exome Sequencing Group: Guerreiro R, Brás J, Sassi C, Gibbs JR, Hernandez D, Lupton MK, Brown K, Morgan K, Powell J, Singleton A, Hardy J.
| | - Florin Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKentuckyUSA,The Research Center for Healthy MetabolismUniversity of KentuckyLexingtonKentuckyUSA,Department of NeurologyUniversity of KentuckyLexingtonKentuckyUSA
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19
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Despa F. Low blood amylin delays Alzheimer’s pathology by modulating brain hypoxia and amyloid composition: A study in humans and rats. Alzheimers Dement 2020. [DOI: 10.1002/alz.045107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Despa F, Goldstein LB, Biessels GJ. Amylin as a Potential Link between Type 2 Diabetes and Alzheimer Disease. Ann Neurol 2020; 87:486. [PMID: 31916276 PMCID: PMC7189609 DOI: 10.1002/ana.25668] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/12/2019] [Accepted: 11/17/2019] [Indexed: 01/11/2023]
Affiliation(s)
- Florin Despa
- Department of Pharmacology and Nutritional Sciences,
University of Kentucky, Lexington, KY, USA,Department of Neurology, University of Kentucky, Lexington,
KY, USA
| | | | - Geert Jan Biessels
- Department of Neurology, University Medical Center Utrecht,
Utrecht, The Netherlands
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21
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Verma N, Liu M, Ly H, Loria A, Campbell KS, Bush H, Kern PA, Jose PA, Taegtmeyer H, Bers DM, Despa S, Goldstein LB, Murray AJ, Despa F. Diabetic microcirculatory disturbances and pathologic erythropoiesis are provoked by deposition of amyloid-forming amylin in red blood cells and capillaries. Kidney Int 2020; 97:143-155. [PMID: 31739987 PMCID: PMC6943180 DOI: 10.1016/j.kint.2019.07.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 01/11/2023]
Abstract
In the setting of type-2 diabetes, there are declines of structural stability and functionality of blood capillaries and red blood cells (RBCs), increasing the risk for microcirculatory disturbances. Correcting hyperglycemia is not entirely effective at reestablishing normal cellular metabolism and function. Therefore, identification of pathological changes occurring before the development of overt hyperglycemia may lead to novel therapeutic targets for reducing the risk of microvascular dysfunction. Here we determine whether RBC-capillary interactions are altered by prediabetic hypersecretion of amylin, an amyloid forming hormone co-synthesized with insulin, and is reversed by endothelial cell-secreted epoxyeicosatrienoic acids. In patients, we found amylin deposition in RBCs in association with type-2 diabetes, heart failure, cancer and stroke. Amylin-coated RBCs have altered shape and reduced functional (non-glycated) hemoglobin. Amylin-coated RBCs administered intravenously in control rats upregulated erythropoietin and renal arginase expression and activity. We also found that diabetic rats expressing amyloid-forming human amylin in the pancreas (the HIP rat model) have increased tissue levels of hypoxia-inducible transcription factors, compared to diabetic rats that express non-amyloid forming rat amylin (the UCD rat model). Upregulation of erythropoietin correlated with lower hematocrit in the HIP model indicating pathologic erythropoiesis. In the HIP model, pharmacological upregulation of endogenous epoxyeicosatrienoic acids protected the renal microvasculature against amylin deposition and also reduced renal accumulation of HIFs. Thus, prediabetes induces dysregulation of amylin homeostasis and promotes amylin deposition in RBCs and the microvasculature altering RBC-capillary interaction leading to activation of hypoxia signaling pathways and pathologic erythropoiesis. Hence, dysregulation of amylin homeostasis could be a therapeutic target for ameliorating diabetic vascular complications.
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Affiliation(s)
- Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Miao Liu
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Han Ly
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Analia Loria
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Heather Bush
- Department of Biostatistics, College of Public Health, University of Kentucky, Lexington, Kentucky, USA
| | - Philip A Kern
- Division of Endocrinology, Department of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Pedro A Jose
- Department of Medicine, Division of Renal Diseases and Hypertension, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Heinrich Taegtmeyer
- Department of Internal Medicine, McGovern Medical School at University of Texas Health, Houston, Texas, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Larry B Goldstein
- Department of Neurology, University of Kentucky, Lexington, Kentucky, USA
| | - Andrew J Murray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA; Department of Neurology, University of Kentucky, Lexington, Kentucky, USA.
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22
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Abstract
The link of diabetes with co-occurring disorders in the brain involves complex and multifactorial pathways. Genetically engineered rodents that express familial Alzheimer's disease-associated mutant forms of amyloid precursor protein and presenilin 1 (PSEN1) genes provided invaluable insights into the mechanisms and consequences of amyloid deposition in the brain. Adding diabetes factors (obesity, insulin impairment) to these animal models to predict success in translation to clinic have proven useful at some extent only. Here, we focus on contributing factors to diabetic brain injury with the aim of identifying appropriate animal models that can be used to mechanistically dissect the pathophysiology of diabetes-associated cognitive dysfunction and how diabetes medications may influence the development and progression of cognitive decline in humans with diabetes.
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Affiliation(s)
- Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
- Department of Neurology, College of Medicine, University of Kentucky, Lexington, KY, USA.
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23
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Ly H, Despa F. Diabetes-related Amylin Dyshomeostasis: a Contributing Factor to Cerebrovascular Pathology and Dementia. J Lipid Atheroscler 2019; 8:144-151. [PMID: 32821704 PMCID: PMC7379112 DOI: 10.12997/jla.2019.8.2.144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/21/2019] [Accepted: 06/04/2019] [Indexed: 01/11/2023] Open
Abstract
Type 2 diabetes (T2D) increases the risk for cerebrovascular disease (CVD) and dementia. The underlying molecular mechanisms remain elusive, which hampers the development of treatment or/and effective prevention strategies. Recent studies suggest that dyshomeostasis of amylin, a satiety hormone that forms pancreatic amyloid in patients with T2D, promotes accumulation of amylin in cerebral small blood vessels and interaction with Alzheimer's disease (AD) pathology. Overexpression of human amylin in rodents (rodent amylin does not form amyloid) leads to late-life onset T2D and neurologic deficits. In this Review, we discuss clinical evidence of amylin pathology in CVD and AD and identify critical characteristics of animal models that could help to better understand molecular mechanisms underlying the increased risk of CVD and AD in patients with prediabetes or T2D.
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Affiliation(s)
- Han Ly
- Departments of Pharmacology and Nutritional Sciences, and Neurology, University of Kentucky, Lexington, KY, USA
| | - Florin Despa
- Departments of Pharmacology and Nutritional Sciences, and Neurology, University of Kentucky, Lexington, KY, USA
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24
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Abstract
Intracellular Na
+
concentration ([Na
+
]
i
) regulates Ca
2+
cycling, oxidative state and electrical stability of the heart. [Na
+
]
i
is linked to glucose uptake through the Na
+
-glucose cotransporter (SGLT). The SGLT1 isoform is present in the heart and its overexpression causes hypertrophy and left-ventricular dysfunction. Here, we hypothesized that cardiac SGLT activity is increased in type-2 diabetes (T2D), which causes myocyte Na
+
overload and results in oxidative stress and exacerbated sarcoplasmic reticulum (SR) Ca
2+
leak. To test this hypothesis, we analyzed myocardial tissue from humans with/without T2D and compared rats with late-onset T2D that display diabetic cardiomyopathy similar to that seen in humans (HIP rats) with their non-diabetic littermates (WT). SGLT1 expression was increased in hearts from T2D patients compared to non-diabetic individuals and in hearts from HIP
vs
. WT rats. SGLT inhibition significantly decreased the uptake of both glucose and Na
+
in myocytes from HIP rats but not in WT, which indicates that SGLT function is increased in T2D hearts. While SGLT1 upregulation may partially compensate for the reduced insulin-dependent glucose uptake, the ensuing raise in Na
+
influx resulted in elevated [Na
+
]
i
in HIP myocytes (by 3 mM compared to WT). Higher [Na
+
]
i
causes oxidative stress by activating the
mitochondrial
Na
+
/Ca
2+
exchanger (mitoNCX), which lowers mitochondrial [Ca
2+
] and thus slows down regeneration of the antioxidant NADPH. In agreement with a role for elevated [Na
+
]
i
in causing oxidative stress in T2D hearts, H
2
O
2
production was increased in HIP myocytes
vs
. WT and mitoNCX inhibition, which uncouples mitochondria from [Na
+
]
i
, significantly reduced H
2
O
2
production in HIP hearts. Oxidative stress enhances the SR Ca
2+
leak directly through oxidation of ryanodine receptors (RyRs) and indirectly via CaMKII activation and consequent RyR phosphorylation. SR Ca
2+
leak was augmented in myocytes from HIP
vs
. WT rats and mitoNCX inhibition significantly reduced the leak in HIP myocytes, but not in the WT. Thus, our data indicate that SGLT activity is enhanced in myocytes from T2D rats, which increases Na
+
influx and causes Na
+
overload. Elevated [Na
+
]
i
contributes to oxidative stress and abnormal SR Ca
2+
leak in diabetic hearts.
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25
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Despa F, Ly H, Verma N, Kotiya D. P4-081: GENETIC MANIPULATION OF AMYLIN DRAMATICALLY ACCELERATES AGING AND BEHAVIORAL CHANGES IN AD RATS. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.06.3741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - Han Ly
- University of Kentucky; Lexington KY USA
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26
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Popescu I, Yin G, Velmurugan S, Erickson JR, Despa F, Despa S. Lower sarcoplasmic reticulum Ca 2+ threshold for triggering afterdepolarizations in diabetic rat hearts. Heart Rhythm 2019; 16:765-772. [PMID: 30414461 PMCID: PMC6491240 DOI: 10.1016/j.hrthm.2018.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Indexed: 01/11/2023]
Abstract
BACKGROUND Type 2 diabetes (T2D) increases arrhythmia risk through incompletely elucidated mechanisms. Ventricular arrhythmias could be initiated by delayed afterdepolarizations (DADs) resulting from elevated spontaneous sarcoplasmic reticulum (SR) Ca2+ release (SR Ca2+ leak). OBJECTIVE The purpose of this study was to test the role of DADs and SR Ca2+ leak in triggering arrhythmias in T2D hearts. METHODS We compared rats with late-onset T2D that display pancreatic and cardiac phenotypes similar to those in humans with T2D (HIP rats) and their nondiabetic littermates (wild type [WT]). RESULTS HIP rats showed higher propensity for premature ventricular complexes and ventricular tachyarrhythmias, whereas HIP myocytes displayed more frequent DADs and had lower SR Ca2+ content than WT. However, the threshold SR Ca2+ at which depolarizing transient inward currents (Itis) are generated was also significantly decreased in HIP myocytes and was below the actual SR Ca2+ load, which explains the increased DAD incidence despite reduced Ca2+ in SR. In agreement with these findings, Ca2+ spark frequency was augmented in myocytes from HIP vs WT rats, which suggests activation of ryanodine receptors (RyRs) in HIP hearts. Indeed, RyR phosphorylation (by CaMKII and protein kinase A) and oxidation are enhanced in HIP hearts, whereas there is no RyR O-GlcNAcylation in either HIP or control hearts. CaMKII inhibition dissipated the difference in Ca2+ spark frequency between HIP and WT myocytes. CONCLUSION The threshold SR Ca2+ for generating depolarizing Itis is lower in T2D because of RyR activation after hyperphosphorylation and oxidation, which favors the occurrence of DADs despite low SR Ca2+ loads.
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Affiliation(s)
- Iuliana Popescu
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Guo Yin
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Sathya Velmurugan
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Jeffrey R Erickson
- Department of Physiology and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky.
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27
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De Rossi P, Andrew RJ, Musial TF, Buggia‐Prevot V, Xu G, Ponnusamy M, Ly H, Krause SV, Rice RC, de l’Estoile V, Valin T, Salem S, Despa F, Borchelt DR, Bindokas VP, Nicholson DA, Thinakaran G. Aberrant accrual of BIN1 near Alzheimer's disease amyloid deposits in transgenic models. Brain Pathol 2018; 29:485-501. [PMID: 30506549 PMCID: PMC6542723 DOI: 10.1111/bpa.12687] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/20/2018] [Indexed: 01/11/2023] Open
Abstract
Bridging integrator 1 (BIN1) is the most significant late-onset Alzheimer's disease (AD) susceptibility locus identified via genome-wide association studies. BIN1 is an adaptor protein that regulates membrane dynamics in the context of endocytosis and membrane remodeling. An increase in BIN1 expression and changes in the relative levels of alternatively spliced BIN1 isoforms have been reported in the brains of patients with AD. BIN1 can bind to Tau, and an increase in BIN1 expression correlates with Tau pathology. In contrast, the loss of BIN1 expression in cultured cells elevates Aβ production and Tau propagation by insfluencing endocytosis and recycling. Here, we show that BIN1 accumulates adjacent to amyloid deposits in vivo. We found an increase in insoluble BIN1 and a striking accrual of BIN1 within and near amyloid deposits in the brains of multiple transgenic models of AD. The peri-deposit aberrant BIN1 localization was conspicuously different from the accumulation of APP and BACE1 within dystrophic neurites. Although BIN1 is highly expressed in mature oligodendrocytes, BIN1 association with amyloid deposits occurred in the absence of the accretion of other oligodendrocyte or myelin proteins. Finally, super-resolution microscopy and immunogold electron microscopy analyses highlight the presence of BIN1 in proximity to amyloid fibrils at the edges of amyloid deposits. These results reveal the aberrant accumulation of BIN1 is a feature associated with AD amyloid pathology. Our findings suggest a potential role for BIN1 in extracellular Aβ deposition in vivo that is distinct from its well-characterized function as an adaptor protein in endocytosis and membrane remodeling.
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Affiliation(s)
- Pierre De Rossi
- Department of NeurobiologyThe University of ChicagoChicagoIL
| | | | - Timothy F. Musial
- Department of Neurological SciencesRush University Medical CenterChicagoIL
| | | | - Guilian Xu
- Center for Translational Research in Neurodegenerative DiseaseUniversity of FloridaGainesvilleFL
| | | | - Han Ly
- Departments of Pharmacology and Nutritional Sciences, and Neurology, College of MedicineUniversity of KentuckyLexingtonKY
| | - Sofia V. Krause
- Department of NeurobiologyThe University of ChicagoChicagoIL
| | - Richard C. Rice
- Department of NeurobiologyThe University of ChicagoChicagoIL
| | | | - Tess Valin
- Department of NeurobiologyThe University of ChicagoChicagoIL
| | - Someya Salem
- Department of NeurobiologyThe University of ChicagoChicagoIL
| | - Florin Despa
- Departments of Pharmacology and Nutritional Sciences, and Neurology, College of MedicineUniversity of KentuckyLexingtonKY
| | - David R. Borchelt
- Center for Translational Research in Neurodegenerative DiseaseUniversity of FloridaGainesvilleFL
| | - Vytas P. Bindokas
- Integrated Light Microscopy FacilityThe University of ChicagoChicagoIL
| | | | - Gopal Thinakaran
- Department of NeurobiologyThe University of ChicagoChicagoIL,Departments of Neurology, and PathologyThe University of Chicago, The University of ChicagoChicagoIL
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28
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Abstract
Cognitive dysfunction is increasingly recognized as an important comorbidity of diabetes mellitus. Different stages of diabetes-associated cognitive dysfunction exist, each with different cognitive features, affected age groups and prognoses and probably with different underlying mechanisms. Relatively subtle, slowly progressive cognitive decrements occur in all age groups. More severe stages, particularly mild cognitive impairment and dementia, with progressive deficits, occur primarily in older individuals (>65 years of age). Patients in the latter group are the most relevant for patient management and are the focus of this Review. Here, we review the evolving insights from studies on risk factors, brain imaging and neuropathology, which provide important clues on mechanisms of both the subtle cognitive decrements and the more severe stages of cognitive dysfunction. In the majority of patients, the cognitive phenotype is probably defined by multiple aetiologies. Although both the risk of clinically diagnosed Alzheimer disease and that of vascular dementia is increased in association with diabetes, the cerebral burden of the prototypical pathologies of Alzheimer disease (such as neurofibrillary tangles and neuritic plaques) is not. A major challenge for researchers is to pinpoint from the spectrum of diabetes-related disease processes those that affect the brain and contribute to development of dementia beyond the pathologies of Alzheimer disease. Observations from experimental models can help to meet that challenge, but this requires further improving the synergy between experimental and clinical scientists. The development of targeted treatment and preventive strategies will therefore depend on these translational efforts.
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Affiliation(s)
- Geert Jan Biessels
- Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands.
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences and Department of Neurology, University of Kentucky, Lexington, KY, USA
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Ly H, Verma N, Wu F, Walton J, Despa F. P2‐077: AMYLIN DYSHOMEOSTASIS: A NON‐AD PROCESS CONTRIBUTING TO AN AD PHENOTYPE. Alzheimers Dement 2018. [DOI: 10.1016/j.jalz.2018.06.762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Han Ly
- University of KentuckyLexingtonKYUSA
| | | | - Fengen Wu
- University of KentuckyLexingtonKYUSA
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Ly H, Verma N, Wu F, Walton J, Despa F. IC‐P‐081: AMYLIN DYSHOMEOSTASIS: A NON‐AD PROCESS CONTRIBUTING TO AN AD PHENOTYPE. Alzheimers Dement 2018. [DOI: 10.1016/j.jalz.2018.06.2145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Han Ly
- University of KentuckyLexingtonKYUSA
| | | | - Fengen Wu
- University of KentuckyLexingtonKYUSA
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Kotiya D, Ly H, Chen L, Despa F. P2‐254: CSF AMYLIN: EFFECT MODIFIER OF THE Aβ‐AD RELATIONSHIP. Alzheimers Dement 2018. [DOI: 10.1016/j.jalz.2018.06.943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
| | - Han Ly
- University of KentuckyLexingtonKYUSA
| | - Lei Chen
- University of KentuckyLexingtonKYUSA
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Verma N, Ly H, Liu M, Chen J, Zhu H, Chow M, Hersh LB, Despa F. Intraneuronal Amylin Deposition, Peroxidative Membrane Injury and Increased IL-1β Synthesis in Brains of Alzheimer's Disease Patients with Type-2 Diabetes and in Diabetic HIP Rats. J Alzheimers Dis 2018; 53:259-72. [PMID: 27163815 DOI: 10.3233/jad-160047] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Amylin is a hormone synthesized and co-secreted with insulin by pancreatic β-cells that crosses the blood-brain barrier and regulates satiety. Amylin from humans (but not rodents) has an increased propensity to aggregate into pancreatic islet amyloid deposits that contribute to β-cell mass depletion and development of type-2 diabetes by inducing oxidative stress and inflammation. Recent studies demonstrated that aggregated amylin also accumulates in brains of Alzheimer's disease (AD) patients, preponderantly those with type-2 diabetes. Here, we report that, in addition to amylin plaques and mixed amylin-Aβ deposits, brains of diabetic patients with AD show amylin immunoreactive deposits inside the neurons. Neuronal amylin formed adducts with 4-hydroxynonenal (4-HNE), a marker of peroxidative membrane injury, and increased synthesis of the proinflammatory cytokine interleukin (IL)-1β. These pathological changes were mirrored in rats expressing human amylin in pancreatic islets (HIP rats) and mice intravenously injected with aggregated human amylin, but not in hyperglycemic rats secreting wild-type non-amyloidogenic rat amylin. In cultured primary hippocampal rat neurons, aggregated amylin increased IL-1β synthesis via membrane destabilization and subsequent generation of 4-HNE. These effects were blocked by membrane stabilizers and lipid peroxidation inhibitors. Thus, elevated circulating levels of aggregated amylin negatively affect the neurons causing peroxidative membrane injury and aberrant inflammatory responses independent of other confounding factors of diabetes. The present results are consistent with the pathological role of aggregated amylin in the pancreas, demonstrate a novel contributing mechanism to neurodegeneration, and suggest a direct, potentially treatable link of type-2 diabetes with AD.
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Affiliation(s)
- Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Han Ly
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Miao Liu
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Jing Chen
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Martin Chow
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Louis B Hersh
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
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Stewart BD, Scott CE, McCoy TP, Yin G, Despa F, Despa S, Kekenes-Huskey PM. Computational modeling of amylin-induced calcium dysregulation in rat ventricular cardiomyocytes. Cell Calcium 2017; 71:65-74. [PMID: 29604965 DOI: 10.1016/j.ceca.2017.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 01/08/2023]
Abstract
Hyperamylinemia is a condition that accompanies obesity and precedes type II diabetes, and it is characterized by above-normal blood levels of amylin, the pancreas-derived peptide. Human amylin oligomerizes easily and can deposit in the pancreas [1], brain [2], and heart [3], where they have been associated with calcium dysregulation. In the heart, accumulating evidence suggests that human amylin oligomers form moderately cation-selective [4,5] channels that embed in the cell sarcolemma (SL). The oligomers increase membrane conductance in a concentration-dependent manner [5], which is correlated with elevated cytosolic Ca2+. These findings motivate our core hypothesis that non-selective inward Ca2+ conduction afforded by human amylin oligomers increase cytosolic and sarcoplasmic reticulum (SR) Ca2+ load, which thereby magnifies intracellular Ca2+ transients. Questions remain however regarding the mechanism of amylin-induced Ca2+ dysregulation, including whether enhanced SL Ca2+ influx is sufficient to elevate cytosolic Ca2+ load [6], and if so, how might amplified Ca2+ transients perturb Ca2+-dependent cardiac pathways. To investigate these questions, we modified a computational model of cardiomyocytes Ca2+ signaling to reflect experimentally-measured changes in SL membrane permeation and decreased sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) function stemming from acute and transgenic human amylin peptide exposure. With this model, we confirmed the hypothesis that increasing SL permeation alone was sufficient to enhance Ca2+ transient amplitudes. Our model indicated that amplified cytosolic transients are driven by increased Ca2+ loading of the SR and that greater fractional release may contribute to the Ca2+-dependent activation of calmodulin, which could prime the activation of myocyte remodeling pathways. Importantly, elevated Ca2+ in the SR and dyadic space collectively drive greater fractional SR Ca2+ release for human amylin expressing rats (HIP) and acute amylin-exposed rats (+Amylin) mice, which contributes to the inotropic rise in cytosolic Ca2+ transients. These findings suggest that increased membrane permeation induced by oligomeratization of amylin peptide in cell sarcolemma contributes to Ca2+ dysregulation in pre-diabetes.
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Affiliation(s)
- Bradley D Stewart
- Department of Chemistry, University of Kentucky, 505 Rose St. Chemistry-Physics Building, Lexington, KY 40506, USA
| | - Caitlin E Scott
- Department of Chemistry, University of Kentucky, 505 Rose St. Chemistry-Physics Building, Lexington, KY 40506, USA
| | - Thomas P McCoy
- Department of Family & Community Nursing, University of North Carolina - Greensboro, 1008 Administration Dr. McIver Building, Greensboro, NC 27412, USA
| | - Guo Yin
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, UK Medical Center, MN 150, Lexington, KY 40536, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, UK Medical Center, MN 150, Lexington, KY 40536, USA
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, UK Medical Center, MN 150, Lexington, KY 40536, USA.
| | - Peter M Kekenes-Huskey
- Department of Chemistry, University of Kentucky, 505 Rose St. Chemistry-Physics Building, Lexington, KY 40506, USA.
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Ly H, Verma N, Wu F, Liu M, Saatman KE, Nelson PT, Slevin JT, Goldstein LB, Biessels GJ, Despa F. Brain microvascular injury and white matter disease provoked by diabetes-associated hyperamylinemia. Ann Neurol 2017; 82:208-222. [PMID: 28696548 DOI: 10.1002/ana.24992] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/20/2017] [Accepted: 07/03/2017] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The brain blood vessels of patients with type 2 diabetes and dementia have deposition of amylin, an amyloidogenic hormone cosecreted with insulin. It is not known whether vascular amylin deposition is a consequence or a trigger of vascular injury. We tested the hypothesis that the vascular amylin deposits cause endothelial dysfunction and microvascular injury and are modulated by amylin transport in the brain via plasma apolipoproteins. METHODS Rats overexpressing amyloidogenic (human) amylin in the pancreas (HIP rats) and amylin knockout (AKO) rats intravenously infused with aggregated amylin were used for in vivo phenotyping. We also carried out biochemical analyses of human brain tissues and studied the effects of the aggregated amylin on endothelial cells ex vivo. RESULTS Amylin deposition in brain blood vessels is associated with vessel wall disruption and abnormal surrounding neuropil in patients with type 2 diabetes and dementia, in HIP rats, and in AKO rats infused with aggregated amylin. HIP rats have brain microhemorrhages, white matter injury, and neurologic deficits. Vascular amylin deposition provokes loss of endothelial cell coverage and tight junctions. Intravenous infusion in AKO rats of human amylin, or combined human amylin and apolipoprotein E4, showed that amylin binds to plasma apolipoproteins. The intravenous infusion of apolipoprotein E4 exacerbated the brain accumulation of aggregated amylin and vascular pathology in HIP rats. INTERPRETATION These data identify vascular amylin deposition as a trigger of brain endothelial dysfunction that is modulated by plasma apolipoproteins and represents a potential therapeutic target in diabetes-associated dementia and stroke. Ann Neurol 2017;82:208-222.
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Affiliation(s)
- Han Ly
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Fengen Wu
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Miao Liu
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Kathryn E Saatman
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY.,Department of Physiology, University of Kentucky, Lexington, KY
| | - Peter T Nelson
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY
| | - John T Slevin
- Veterans Administration Medical Center, Lexington, KY.,Department of Neurology, University of Kentucky, Lexington, KY
| | | | - Geert Jan Biessels
- Department of Neurology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY.,Department of Neurology, University of Kentucky, Lexington, KY
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Ly H, Verma N, Liu M, Wu F, Despa F. [IC‐P‐046]: DIABETES‐ASSOCIATED AMYLIN DYSHOMEOSTASIS PROVOKES BRAIN WHITE MATTER DISEASE AND BEHAVIOR CHANGES: AN ANIMAL MODEL. Alzheimers Dement 2017. [DOI: 10.1016/j.jalz.2017.06.2318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Han Ly
- University of KentuckyLexingtonKYUSA
| | | | - Miao Liu
- University of KentuckyLexingtonKYUSA
| | - Fengen Wu
- University of KentuckyLexingtonKYUSA
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Van Steenbergen A, Balteau M, Ginion A, Ferté L, Battault S, Ravenstein CDMD, Balligand JL, Daskalopoulos EP, Gilon P, Despa F, Despa S, Vanoverschelde JL, Horman S, Koepsell H, Berry G, Hue L, Bertrand L, Beauloye C. Sodium-myoinositol cotransporter-1, SMIT1, mediates the production of reactive oxygen species induced by hyperglycemia in the heart. Sci Rep 2017; 7:41166. [PMID: 28128227 PMCID: PMC5269587 DOI: 10.1038/srep41166] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/16/2016] [Indexed: 01/04/2023] Open
Abstract
Hyperglycemia (HG) stimulates the production of reactive oxygen species in the heart through activation of NADPH oxidase 2 (NOX2). This production is independent of glucose metabolism but requires sodium/glucose cotransporters (SGLT). Seven SGLT isoforms (SGLT1 to 6 and sodium-myoinositol cotransporter-1, SMIT1) are known, although their expression and function in the heart remain elusive. We investigated these 7 isoforms and found that only SGLT1 and SMIT1 were expressed in mouse, rat and human hearts. In cardiomyocytes, galactose (transported through SGLT1) did not activate NOX2. Accordingly, SGLT1 deficiency did not prevent HG-induced NOX2 activation, ruling it out in the cellular response to HG. In contrast, myo-inositol (transported through SMIT1) reproduced the toxic effects of HG. SMIT1 overexpression exacerbated glucotoxicity and sensitized cardiomyocytes to HG, whereas its deletion prevented HG-induced NOX2 activation. In conclusion, our results show that heart SMIT1 senses HG and triggers NOX2 activation. This could participate in the redox signaling in hyperglycemic heart and contribute to the pathophysiology of diabetic cardiomyopathy.
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Affiliation(s)
- Anne Van Steenbergen
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Magali Balteau
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Audrey Ginion
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Laura Ferté
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Sylvain Battault
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | | | - Jean-Luc Balligand
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Pharmacology and Therapeutics, Brussels, Belgium.,Cliniques Universitaires Saint-Luc, Department of Medicine, Brussels, Belgium
| | - Evangelos-Panagiotis Daskalopoulos
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Florin Despa
- University of Kentucky, Department of Pharmacology and Nutritional Sciences, Lexington, KY, USA
| | - Sanda Despa
- University of Kentucky, Department of Pharmacology and Nutritional Sciences, Lexington, KY, USA
| | - Jean-Louis Vanoverschelde
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium.,Cliniques Universitaires Saint Luc, Division of Cardiology, Brussels, Belgium
| | - Sandrine Horman
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Hermann Koepsell
- University of Würzburg, Department of Molecular Plant Physiology and Biophysics, Julius von Sachs Institute, Würzburg, Germany
| | - Gerard Berry
- Harvard Medical School, Children's Hospital Boston, Division of Genetics and Genomics, Department of Pediatrics, Boston, MA, USA
| | - Louis Hue
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium.,Université catholique de Louvain, de Duve Institute, Brussels, Belgium
| | - Luc Bertrand
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Christophe Beauloye
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium.,Cliniques Universitaires Saint Luc, Division of Cardiology, Brussels, Belgium
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Liu M, Verma N, Peng X, Srodulski S, Morris A, Chow M, Hersh LB, Chen J, Zhu H, Netea MG, Margulies KB, Despa S, Despa F. Hyperamylinemia Increases IL-1β Synthesis in the Heart via Peroxidative Sarcolemmal Injury. Diabetes 2016; 65:2772-83. [PMID: 27335231 PMCID: PMC5001184 DOI: 10.2337/db16-0044] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 06/09/2016] [Indexed: 12/29/2022]
Abstract
Hypersecretion of amylin is common in individuals with prediabetes, causes amylin deposition and proteotoxicity in pancreatic islets, and contributes to the development of type 2 diabetes. Recent studies also identified amylin deposits in failing hearts from patients with obesity or type 2 diabetes and demonstrated that hyperamylinemia accelerates the development of heart dysfunction in rats expressing human amylin in pancreatic β-cells (HIP rats). To further determine the impact of hyperamylinemia on cardiac myocytes, we investigated human myocardium, compared diabetic HIP rats with diabetic rats expressing endogenous (nonamyloidogenic) rat amylin, studied normal mice injected with aggregated human amylin, and developed in vitro cell models. We found that amylin deposition negatively affects cardiac myocytes by inducing sarcolemmal injury, generating reactive aldehydes, forming amylin-based adducts with reactive aldehydes, and increasing synthesis of the proinflammatory cytokine interleukin-1β (IL-1β) independently of hyperglycemia. These results are consistent with the pathological role of amylin deposition in the pancreas, uncover a novel contributing mechanism to cardiac myocyte injury in type 2 diabetes, and suggest a potentially treatable link of type 2 diabetes with diabetic heart disease. Although further studies are necessary, these data also suggest that IL-1β might function as a sensor of myocyte amylin uptake and a potential mediator of myocyte injury.
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Affiliation(s)
- Miao Liu
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY
| | - Nirmal Verma
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY
| | - Xiaoli Peng
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY
| | - Sarah Srodulski
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY
| | - Andrew Morris
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky, Lexington, KY
| | - Martin Chow
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY
| | - Louis B Hersh
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY
| | - Jing Chen
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY
| | - Mihai G Netea
- Department of Internal Medicine, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands
| | - Kenneth B Margulies
- Cardiovascular Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY
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Despa F, Verma N, Ly H, Liu M, Chen J, Zhu H, Hersh L. P2‐059: Intraneuronal Amylin Deposition, Peroxidative Membrane Injury and Increased IL‐1SS Synthesis in Brains of Alzheimer’s Disease Patients with Type‐2 Diabetes and Diabetic Hip Rats. Alzheimers Dement 2016. [DOI: 10.1016/j.jalz.2016.06.1264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | | | - Han Ly
- University of KentuckyLexingtonKY USA
| | - Miao Liu
- University of KentuckyLexingtonKY USA
| | - Jing Chen
- University of KentuckyLexingtonKY USA
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Ilaiwy A, Liu M, Parry TL, Bain JR, Newgard CB, Schisler JC, Muehlbauer MJ, Despa F, Willis MS. Human amylin proteotoxicity impairs protein biosynthesis, and alters major cellular signaling pathways in the heart, brain and liver of humanized diabetic rat model in vivo. Metabolomics 2016; 12:95. [PMID: 28775675 PMCID: PMC5538143 DOI: 10.1007/s11306-016-1022-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Chronic hypersecretion of the 37 amino acid amylin is common in type 2 diabetics (T2D). Recent studies implicate human amylin aggregates cause proteotoxicity (cell death induced by misfolded proteins) in both the brain and the heart. OBJECTIVES Identify systemic mechanisms/markers by which human amylin associated with cardiac and brain defects might be identified. METHODS We investigated the metabolic consequences of amyloidogenic and cytotoxic amylin oligomers in heart, brain, liver, and plasma using non-targeted metabolomics analysis in a rat model expressing pancreatic human amylin (HIP model). RESULTS Four metabolites were significantly different in 3 or more of the the four compartments (heart, brain, liver, and plasma) in HIP rats. When compared to a T2D rat model, HIP hearts uniquely had significant DECREASES in five amino acids (lysine, alanine, tyrosine, phenylalanine, serine), with phenylalanine decreased across all four tissues investigated, including plasma. In contrast, significantly INCREASED circulating phenylalanine is reported in diabetics in multiple recent studies. CONCLUSION DECREASED phenylalanine may serve as a unique marker of cardiac and brain dysfunction due to hyperamylinemia that can be differentiated from alterations in T2D in the plasma. While the deficiency in phenylalanine was seen across tissues including plasma and could be monitored, reduced tyrosine was seen only in the brain. The 50% reduction in phenylalanine and tyrosine in HIP brains is significant given their role in supporting brain chemistry as a precursor for catecholamines (dopamine, norepinephrine, epinephrine), which may contribute to the increased morbidity and mortality in diabetics at a multi-system level beyond the effects on glucose metabolism.
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Affiliation(s)
| | - Miao Liu
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Traci L Parry
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC, USA
| | - James R Bain
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
| | - Christopher B Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
| | - Jonathan C Schisler
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Michael J Muehlbauer
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Monte S Willis
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
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40
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Ilaiwy A, Liu M, Parry TS, Bain JR, Muehlbauer MJ, Willis MS, Despa F. Human amylin proteotoxicity impairs protein biosynthesis, and alters major cellular signaling pathways in the heart, brain and liver of humanized diabetic rat model in vivo. FASEB J 2016. [DOI: 10.1096/fasebj.30.1_supplement.lb461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Amro Ilaiwy
- Department of Internal MedicineDivision of Endocrinology, Metabolism, and NutritionDuke University Medical CenterDurhamNC
| | - Miao Liu
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKY
| | - Traci S. Parry
- Department of Pathology & Laboratory MedicineUniv of North CarolinaChapel HillNC
- McAllister Heart InstituteUniv of North CarolinaChapel HIllNC
| | - James R. Bain
- Department of Internal MedicineDivision of Endocrinology, Metabolism, and NutritionDuke University Medical CenterDurhamNC
| | | | - Monte S. Willis
- PharmacologyUniv of North CarolinaChapel HillNC
- Department of Pathology & Laboratory MedicineUniversity of North CarolinaChapel HillNC
| | - Florin Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKY
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Abstract
Type II diabetes increases the risk for cognitive decline via multiple traits. Amylin is a pancreatic hormone that has amyloidogenic and cytotoxic properties similar to the amyloid-β peptide. The amylin hormone is overexpressed in individuals with pre-diabetic insulin resistance or obesity leading to amylin oligomerization and deposition in pancreatic islets. Amylin oligomerization was implicated in the apoptosis of the insulin-producing β-cells. Recent studies showed that brain tissue from diabetic patients with cerebrovascular dementia or Alzheimer's disease contains significant deposits of oligomerized amylin. It has also been reported that the brain amylin deposition reduced exploratory drive, recognition memory and vestibulomotor function in a rat model that overexpresses human amylin in the pancreas. These novel findings are reviewed here and the hypothesis that type II diabetes is linked with cognitive decline by amylin accumulation in the brain is proposed. Deciphering the impact of hyperamylinemia on the brain is critical for both etiology and treatment of dementia.
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Affiliation(s)
- Han Ly
- a Department of Pharmacology and Nutritional Sciences , University of Kentucky, College of Medicine , Lexington , KY 40536 , USA
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Lambert R, Srodulski S, Peng X, Margulies KB, Despa F, Despa S. Intracellular Na+ Concentration ([Na+]i) Is Elevated in Diabetic Hearts Due to Enhanced Na+-Glucose Cotransport. J Am Heart Assoc 2015; 4:e002183. [PMID: 26316524 PMCID: PMC4599504 DOI: 10.1161/jaha.115.002183] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background Intracellular Na+ concentration ([Na+]i) regulates Ca2+ cycling, contractility, metabolism, and electrical stability of the heart. [Na+]i is elevated in heart failure, leading to arrhythmias and oxidative stress. We hypothesized that myocyte [Na+]i is also increased in type 2 diabetes (T2D) due to enhanced activity of the Na+–glucose cotransporter. Methods and Results To test this hypothesis, we used myocardial tissue from humans with T2D and a rat model of late-onset T2D (HIP rat). Western blot analysis showed increased Na+–glucose cotransporter expression in failing hearts from T2D patients compared with nondiabetic persons (by 73±13%) and in HIP rat hearts versus wild-type (WT) littermates (by 61±8%). [Na+]i was elevated in HIP rat myocytes both at rest (14.7±0.9 versus 11.4±0.7 mmol/L in WT) and during electrical stimulation (17.3±0.8 versus 15.0±0.7 mmol/L); however, the Na+/K+-pump function was similar in HIP and WT cells, suggesting that higher [Na+]i is due to enhanced Na+ entry in diabetic hearts. Indeed, Na+ influx was significantly larger in myocytes from HIP versus WT rats (1.77±0.11 versus 1.29±0.06 mmol/L per minute). Na+–glucose cotransporter inhibition with phlorizin or glucose-free solution greatly reduced Na+ influx in HIP myocytes (to 1.20±0.16 mmol/L per minute), whereas it had no effect in WT cells. Phlorizin also significantly decreased glucose uptake in HIP myocytes (by 33±9%) but not in WT, indicating an increased reliance on the Na+–glucose cotransporter for glucose uptake in T2D hearts. Conclusions Myocyte Na+–glucose cotransport is enhanced in T2D, which increases Na+ influx and causes Na+ overload. Higher [Na+]i may contribute to arrhythmogenesis and oxidative stress in diabetic hearts.
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Affiliation(s)
- Rebekah Lambert
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Sarah Srodulski
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Xiaoli Peng
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Kenneth B Margulies
- Cardiovascular Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA (K.B.M.)
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
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Guan H, Chow KM, Song E, Verma N, Despa F, Hersh LB. The Mitochondrial Peptidase Pitrilysin Degrades Islet Amyloid Polypeptide in Beta-Cells. PLoS One 2015; 10:e0133263. [PMID: 26191799 PMCID: PMC4507941 DOI: 10.1371/journal.pone.0133263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 06/25/2015] [Indexed: 01/09/2023] Open
Abstract
Amyloid formation and mitochondrial dysfunction are characteristics of type 2 diabetes. The major peptide constituent of the amyloid deposits in type 2 diabetes is islet amyloid polypeptide (IAPP). In this study, we found that pitrilysin, a zinc metallopeptidase of the inverzincin family, degrades monomeric, but not oligomeric, islet amyloid polypeptide in vitro. In insulinoma cells when pitrilysin expression was decreased to 5% of normal levels, there was a 60% increase in islet amyloid polypeptide-induced apoptosis. In contrast, overexpression of pitrilysin protects insulinoma cells from human islet amyloid polypeptide-induced apoptosis. Since pitrilysin is a mitochondrial protein, we used immunofluorescence staining of pancreases from human IAPP transgenic mice and Western blot analysis of IAPP in isolated mitochondria from insulinoma cells to provide evidence for a putative intramitochondrial pool of IAPP. These results suggest that pitrilysin regulates islet amyloid polypeptide in beta cells and suggest the presence of an intramitochondrial pool of islet amyloid polypeptide involved in beta-cell apoptosis.
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Affiliation(s)
- Hanjun Guan
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Biomedical Biological Sciences Research Building, 741 South Limestone St., Lexington, KY, 40536–0509, United States of America
- * E-mail:
| | - K. Martin Chow
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Biomedical Biological Sciences Research Building, 741 South Limestone St., Lexington, KY, 40536–0509, United States of America
| | - Eunsuk Song
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Biomedical Biological Sciences Research Building, 741 South Limestone St., Lexington, KY, 40536–0509, United States of America
| | - Nirmal Verma
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 459 Wethington Bldg., 800 Rose St., Lexington, KY, 40536–0200, United States of America
| | - Florin Despa
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 459 Wethington Bldg., 800 Rose St., Lexington, KY, 40536–0200, United States of America
| | - Louis B. Hersh
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Biomedical Biological Sciences Research Building, 741 South Limestone St., Lexington, KY, 40536–0509, United States of America
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Verma N, Mina M, Liu M, Nystoriak M, Srodulski S, Peng XL, Brelsfoard J, Bachstetter A, Pascual C, Xie X, Saatman K, Van Eldik L, Navedo M, Despa S, Despa F. Abstract W P252: Amylin Vasculopathy, a Novel Mechanism of Cerebrovascular Injury and Neurologic Deficits in Diabetes. Stroke 2015. [DOI: 10.1161/str.46.suppl_1.wp252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human amylin is an amyloidogenic hormone that forms toxic oligomers that kill the insulin-producing β-cells in the pancreas of patients with type-2 diabetes. We recently showed that the pancreatic amylin pathology is also linked with cerebrovascular dementia and diabetic heart disease by increased circulating levels of toxic oligomerized amylin. Here, we tested the hypothesis that the cerebrovascular accumulation of oligomerized amylin injures the brain, leading to neurologic deficits independently of hyperglycemia.
A diabetic rat model overexpressing amyloidogenic human amylin in the pancreas (the HIP rat) and appropriate controls were used to investigate mechanistically cerebrovascular effects of amylin accumulation. As controls, we employed wild-type (WT) littermates and age- and glucose-matched diabetic rats expressing only non-amyloidogenic WT amylin, which does not accumulate in pancreas or other organs. Compared to controls, HIP rats showed reduced exploratory drive, vestibulomotor performance and recognition memory. Cortical arteries isolated from HIP rats displayed a ~40% higher myogenic tone (P<0.05), which correlates with an increased mean arterial blood pressure by ~20% (P<0.05). We also found elevated lipid peroxidation (by 18±3%; P<0.05) and activated Ca
2+
-mediated hypertrophy signaling in cortical smooth muscle cells from HIP rats compared to control rats. Serial staining with the ED1 antibody and amylin antibody indicates possible activated microglia/macrophages which are clustering in blood vessel areas positive for amylin infiltration. Multiple inflammatory markers are expressed in HIP rat brains compared to control rats, confirming that amylin deposition induces an inflammatory response.
Overall, our data suggest that cerebrovascular amylin deposition is associated with neurologic deficits via mechanisms of vascular dysfunction, oxidative stress and neuroinflammation.
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Affiliation(s)
| | | | - Miao Liu
- Pharmacology, Univ of Kentucky, Lexington, KY
| | | | | | | | | | | | | | - Xinmin Xie
- Pharmacology, Afasci Rsch Laboratory, Redwood, CA
| | | | | | | | - Sanda Despa
- Pharmacology, Univ of Kentucky, Lexington, KY
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Srodulski S, Sharma S, Bachstetter AB, Brelsfoard JM, Pascual C, Xie XS, Saatman KE, Van Eldik LJ, Despa F. Neuroinflammation and neurologic deficits in diabetes linked to brain accumulation of amylin. Mol Neurodegener 2014. [PMID: 25149184 DOI: 10.1186/1750-1326-9-30 doi: 10.1186/1750-1326-9-30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND We recently found that brain tissue from patients with type-2 diabetes (T2D) and cognitive impairment contains deposits of amylin, an amyloidogenic hormone synthesized and co-secreted with insulin by pancreatic β-cells. Amylin deposition is promoted by chronic hypersecretion of amylin (hyperamylinemia), which is common in humans with obesity or pre-diabetic insulin resistance. Human amylin oligomerizes quickly when oversecreted, which is toxic, induces inflammation in pancreatic islets and contributes to the development of T2D. Here, we tested the hypothesis that accumulation of oligomerized amylin affects brain function. METHODS In contrast to amylin from humans, rodent amylin is neither amyloidogenic nor cytotoxic. We exploited this fact by comparing rats overexpressing human amylin in the pancreas (HIP rats) with their littermate rats which express only wild-type (WT) non-amyloidogenic rodent amylin. Cage activity, rotarod and novel object recognition tests were performed on animals nine months of age or older. Amylin deposition in the brain was documented by immunohistochemistry, and western blot. We also measured neuroinflammation by immunohistochemistry, quantitative real-time PCR and cytokine protein levels. RESULTS Compared to WT rats, HIP rats show i) reduced exploratory drive, ii) impaired recognition memory and iii) no ability to improve the performance on the rotarod. The development of neurological deficits is associated with amylin accumulation in the brain. The level of oligomerized amylin in supernatant fractions and pellets from brain homogenates is almost double in HIP rats compared with WT littermates (P < 0.05). Large amylin deposits (>50 μm diameter) were also occasionally seen in HIP rat brains. Accumulation of oligomerized amylin alters the brain structure at the molecular level. Immunohistochemistry analysis with an ED1 antibody indicates possible activated microglia/macrophages which are clustering in areas positive for amylin infiltration. Multiple inflammatory markers are expressed in HIP rat brains as opposed to WT rats, confirming that amylin deposition in the brain induces a neuroinflammatory response. CONCLUSIONS Hyperamylinemia promotes accumulation of oligomerized amylin in the brain leading to neurological deficits through an oligomerized amylin-mediated inflammatory response. Additional studies are needed to determine whether brain amylin accumulation may predispose to diabetic brain injury and cognitive decline.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA.
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Srodulski S, Sharma S, Bachstetter AB, Brelsfoard JM, Pascual C, Xie XS, Saatman KE, Van Eldik LJ, Despa F. Neuroinflammation and neurologic deficits in diabetes linked to brain accumulation of amylin. Mol Neurodegener 2014; 9:30. [PMID: 25149184 PMCID: PMC4144699 DOI: 10.1186/1750-1326-9-30] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 08/18/2014] [Indexed: 12/23/2022] Open
Abstract
Background We recently found that brain tissue from patients with type-2 diabetes (T2D) and cognitive impairment contains deposits of amylin, an amyloidogenic hormone synthesized and co-secreted with insulin by pancreatic β-cells. Amylin deposition is promoted by chronic hypersecretion of amylin (hyperamylinemia), which is common in humans with obesity or pre-diabetic insulin resistance. Human amylin oligomerizes quickly when oversecreted, which is toxic, induces inflammation in pancreatic islets and contributes to the development of T2D. Here, we tested the hypothesis that accumulation of oligomerized amylin affects brain function. Methods In contrast to amylin from humans, rodent amylin is neither amyloidogenic nor cytotoxic. We exploited this fact by comparing rats overexpressing human amylin in the pancreas (HIP rats) with their littermate rats which express only wild-type (WT) non-amyloidogenic rodent amylin. Cage activity, rotarod and novel object recognition tests were performed on animals nine months of age or older. Amylin deposition in the brain was documented by immunohistochemistry, and western blot. We also measured neuroinflammation by immunohistochemistry, quantitative real-time PCR and cytokine protein levels. Results Compared to WT rats, HIP rats show i) reduced exploratory drive, ii) impaired recognition memory and iii) no ability to improve the performance on the rotarod. The development of neurological deficits is associated with amylin accumulation in the brain. The level of oligomerized amylin in supernatant fractions and pellets from brain homogenates is almost double in HIP rats compared with WT littermates (P < 0.05). Large amylin deposits (>50 μm diameter) were also occasionally seen in HIP rat brains. Accumulation of oligomerized amylin alters the brain structure at the molecular level. Immunohistochemistry analysis with an ED1 antibody indicates possible activated microglia/macrophages which are clustering in areas positive for amylin infiltration. Multiple inflammatory markers are expressed in HIP rat brains as opposed to WT rats, confirming that amylin deposition in the brain induces a neuroinflammatory response. Conclusions Hyperamylinemia promotes accumulation of oligomerized amylin in the brain leading to neurological deficits through an oligomerized amylin-mediated inflammatory response. Additional studies are needed to determine whether brain amylin accumulation may predispose to diabetic brain injury and cognitive decline.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA.
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Despa S, Sharma S, Harris TR, Dong H, Li N, Chiamvimonvat N, Taegtmeyer H, Margulies KB, Hammock BD, Despa F. Cardioprotection by controlling hyperamylinemia in a "humanized" diabetic rat model. J Am Heart Assoc 2014; 3:jah3658. [PMID: 25146704 PMCID: PMC4310392 DOI: 10.1161/jaha.114.001015] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND Chronic hypersecretion of the pancreatic hormone amylin is common in humans with obesity or prediabetic insulin resistance and induces amylin aggregation and proteotoxicity in the pancreas. We recently showed that hyperamylinemia also affects the cardiovascular system. Here, we investigated whether amylin aggregates interact directly with cardiac myocytes and whether controlling hyperamylinemia protects the heart. METHODS AND RESULTS By Western blot, we found abundant amylin aggregates in lysates of cardiac myocytes from obese patients, but not in controls. Aggregated amylin was elevated in failing hearts, suggesting a role in myocyte injury. Using rats overexpressing human amylin in the pancreas (HIP rats) and control myocytes incubated with human amylin, we show that amylin aggregation at the sarcolemma induces oxidative stress and Ca(2+) dysregulation. In time, HIP rats developed cardiac hypertrophy and left-ventricular dilation. We then tested whether metabolites with antiaggregation properties, such as eicosanoid acids, limit myocardial amylin deposition. Rats were treated with an inhibitor of soluble epoxide hydrolase, the enzyme that degrades endogenous eicosanoids. Treatment doubled the blood concentration of eicosanoids, which drastically reduced incorporation of aggregated amylin in cardiac myocytes and blood cells, without affecting pancreatic amylin secretion. Animals in the treated group showed reduced cardiac hypertrophy and left-ventricular dilation. The cardioprotective mechanisms included the mitigation of amylin-induced cardiac oxidative stress and Ca(2+) dysregulation. CONCLUSIONS The results suggest blood amylin as a novel therapeutic target in diabetic heart disease and elevating blood levels of antiaggregation metabolites as a pharmacological strategy to reduce amylin aggregation and amylin-mediated cardiotoxicity.
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Affiliation(s)
- Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (S.D., S.S., F.D.) Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY (S.D., F.D.)
| | - Savita Sharma
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (S.D., S.S., F.D.)
| | - Todd R Harris
- Department of Entomology, University of California, Davis, CA (T.R.H., H.D., B.D.H.)
| | - Hua Dong
- Department of Entomology, University of California, Davis, CA (T.R.H., H.D., B.D.H.)
| | - Ning Li
- Department of Internal Medicine, University of California, Davis, CA (N.L., N.C.)
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, CA (N.L., N.C.) Department of Veterans Affairs, Northern California Health Care System, Mather, CA (N.C.)
| | - Heinrich Taegtmeyer
- Department of Internal Medicine, The University of Texas School of Medicine at Houston, Houston, TX (H.T.)
| | - Kenneth B Margulies
- Cardiovascular Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA (K.B.M.)
| | - Bruce D Hammock
- Department of Entomology, University of California, Davis, CA (T.R.H., H.D., B.D.H.)
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (S.D., S.S., F.D.) Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY (S.D., F.D.)
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Affiliation(s)
- Florin Despa
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 900 S Limestone, Lexington, KY 40536, USA
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49
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Jackson K, Xie S, Despa F. Amylin Interacts with Aβ and May Accelerate the Development of Dementia. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Erickson JR, Pereira L, Wang L, Han G, Ferguson A, Dao K, Copeland RJ, Despa F, Hart GW, Ripplinger CM, Bers DM. Diabetic hyperglycaemia activates CaMKII and arrhythmias by O-linked glycosylation. Nature 2013; 502:372-6. [PMID: 24077098 PMCID: PMC3801227 DOI: 10.1038/nature12537] [Citation(s) in RCA: 452] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 08/12/2013] [Indexed: 01/26/2023]
Abstract
Ca2+-Calmodulin dependent protein kinase II (CaMKII) is a regulatory node in heart and brain, and its chronic activation can be pathological. CaMKII activation seen in heart failure can directly induce pathological changes in ion channels, Ca2+ handling and gene transcription.1 Here we discover a novel mechanism linking CaMKII and hyperglycemic signaling in diabetes mellitus, which is a key risk factor for heart2 and neurodegenerative diseases.3,4 Acute hyperglycemia causes covalent modification of CaMKII by O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAc modification of CaMKII at Ser-279 activates CaMKII autonomously, creating molecular memory even after [Ca2+] declines. O-GlcNAc modified CaMKII is increased in heart and brain from diabetic humans and rats. In cardiomyocytes, increased [glucose] significantly enhances CaMKII-dependent activation of spontaneous sarcoplasmic reticulum (SR) Ca2+ release events that can contribute to cardiac mechanical dysfunction and arrhythmias.1 These effects were prevented by pharmacological inhibition of O-GlcNAc signaling or genetic ablation of CaMKIIδ. In intact perfused hearts, arrhythmias were enhanced by increased [glucose] via O-GlcNAc-and CaMKII-dependent pathways. In diabetic animals, acute blockade of O-GlcNAc inhibited arrhythmogenesis. Thus, O-GlcNAc modification of CaMKII is a novel signaling event in pathways that may contribute critically to cardiac and neuronal pathophysiology in diabetes and other diseases.
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Affiliation(s)
- Jeffrey R Erickson
- Department of Pharmacology, University of California, Davis, Davis, California 95616, USA
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