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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: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [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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Zhang L, Li C, Zhu Q, Li N, Zhou H. Liraglutide, a glucagon-like peptide-1 analog, inhibits high glucose-induced oxidative stress and apoptosis in neonatal rat cardiomyocytes. Exp Ther Med 2019; 17:3734-3740. [PMID: 30988759 DOI: 10.3892/etm.2019.7388] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 01/24/2019] [Indexed: 12/12/2022] Open
Abstract
Cardiomyocyte apoptosis serves an important role in diabetic cardiomyopathy. Liraglutide, a glucagon-like peptide-1 analog, has been indicated to exert a cardioprotective effect. However, the role of liraglutide on cardiomyocyte apoptosis in hyperglycemia is not fully understood. The aim of the current study was to assess whether liraglutide protects against high glucose (HG)-induced cardiomyocyte apoptosis in vitro. Sprague-Dawley neonatal rat cardiomyocytes were cultured in Dulbecco's modified Eagle's medium, supplemented with 5.5 or 25 mmol/l D-glucose or 5.5 mmol/l D-glucose + 19.5 mmol/l mannitol, in the presence or absence of liraglutide (10 or 100 nmol/l). Cell viability was assessed via an MTT assay and early apoptosis rates were assessed via flow cytometry. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in cell supernatants were measured. Bcl-2 associated X (Bax), B-cell lymphoma-2 (Bcl-2) and cleaved/full caspase-3 protein levels were determined via western blotting. The results revealed that liraglutide effectively inhibited the HG-induced increase in early apoptosis and MDA content and markedly increased SOD activity. Furthermore, liraglutide markedly inhibited the HG-induced increase in Bax and cleaved caspase-3 protein expression, and upregulated the expression of Bcl-2. The present study demonstrated that liraglutide suppressed HG-induced oxidative stress and cardiomyocyte apoptosis. Thus, the anti-apoptotic actions of liraglutide may be attributable, in part, to the inhibition of Bax, the inhibition of caspase-3 activation and the upregualtion of Bcl-2.
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Affiliation(s)
- Lihui Zhang
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
| | - Caige Li
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
| | - Qiuxiao Zhu
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
| | - Na Li
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
| | - Hong Zhou
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
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Hegyi B, Bers DM, Bossuyt J. CaMKII signaling in heart diseases: Emerging role in diabetic cardiomyopathy. J Mol Cell Cardiol 2019; 127:246-259. [PMID: 30633874 DOI: 10.1016/j.yjmcc.2019.01.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 01/04/2019] [Indexed: 02/07/2023]
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is upregulated in diabetes and significantly contributes to cardiac remodeling with increased risk of cardiac arrhythmias. Diabetes is frequently associated with atrial fibrillation, coronary artery disease, and heart failure, which may further enhance CaMKII. Activation of CaMKII occurs downstream of neurohormonal stimulation (e.g. via G-protein coupled receptors) and involve various posttranslational modifications including autophosphorylation, oxidation, S-nitrosylation and O-GlcNAcylation. CaMKII signaling regulates diverse cellular processes in a spatiotemporal manner including excitation-contraction and excitation-transcription coupling, mechanics and energetics in cardiac myocytes. Chronic activation of CaMKII results in cellular remodeling and ultimately arrhythmogenic alterations in Ca2+ handling, ion channels, cell-to-cell coupling and metabolism. This review addresses the detrimental effects of the upregulated CaMKII signaling to enhance the arrhythmogenic substrate and trigger mechanisms in the heart. We also briefly summarize preclinical studies using kinase inhibitors and genetically modified mice targeting CaMKII in diabetes. The mechanistic understanding of CaMKII signaling, cardiac remodeling and arrhythmia mechanisms may reveal new therapeutic targets and ultimately better treatment in diabetes and heart disease in general.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA.
| | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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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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Despa S. Myocyte [Na +] i Dysregulation in Heart Failure and Diabetic Cardiomyopathy. Front Physiol 2018; 9:1303. [PMID: 30258369 PMCID: PMC6144935 DOI: 10.3389/fphys.2018.01303] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/29/2018] [Indexed: 12/19/2022] Open
Abstract
By controlling the function of various sarcolemmal and mitochondrial ion transporters, intracellular Na+ concentration ([Na+]i) regulates Ca2+ cycling, electrical activity, the matching of energy supply and demand, and oxidative stress in cardiac myocytes. Thus, maintenance of myocyte Na+ homeostasis is vital for preserving the electrical and contractile activity of the heart. [Na+]i is set by the balance between the passive Na+ entry through numerous pathways and the pumping of Na+ out of the cell by the Na+/K+-ATPase. This equilibrium is perturbed in heart failure, resulting in higher [Na+]i. More recent studies have revealed that [Na+]i is also increased in myocytes from diabetic hearts. Elevated [Na+]i causes oxidative stress and augments the sarcoplasmic reticulum Ca2+ leak, thus amplifying the risk for arrhythmias and promoting heart dysfunction. This mini-review compares and contrasts the alterations in Na+ extrusion and/or Na+ uptake that underlie the [Na+]i increase in heart failure and diabetes, with a particular emphasis on the emerging role of Na+ - glucose cotransporters in the diabetic heart.
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Affiliation(s)
- Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, United States
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IAPP in type II diabetes: Basic research on structure, molecular interactions, and disease mechanisms suggests potential intervention strategies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018. [DOI: 10.1016/j.bbamem.2018.02.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Pilkington EH, Gustafsson OJR, Xing Y, Hernandez-Fernaud J, Zampronio C, Kakinen A, Faridi A, Ding F, Wilson P, Ke PC, Davis TP. Profiling the Serum Protein Corona of Fibrillar Human Islet Amyloid Polypeptide. ACS NANO 2018; 12:6066-6078. [PMID: 29746093 PMCID: PMC6239983 DOI: 10.1021/acsnano.8b02346] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Amyloids may be regarded as native nanomaterials that form in the presence of complex protein mixtures. By drawing an analogy with the physicochemical properties of nanoparticles in biological fluids, we hypothesized that amyloids should form a protein corona in vivo that would imbue the underlying amyloid with a modified biological identity. To explore this hypothesis, we characterized the protein corona of human islet amyloid polypeptide (IAPP) fibrils in fetal bovine serum using two complementary methodologies developed herein: quartz crystal microbalance and "centrifugal capture", coupled with nanoliquid chromatography tandem mass spectroscopy. Clear evidence for a significant protein corona was obtained. No trends were identified for amyloid corona proteins based on their physicochemical properties, whereas strong binding with IAPP fibrils occurred for linear proteins or multidomain proteins with structural plasticity. Proteomic analysis identified amyloid-enriched proteins that are known to play significant roles in mediating cellular machinery and processing, potentially leading to pathological outcomes and therapeutic targets.
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Affiliation(s)
- Emily H Pilkington
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology , Monash Institute of Pharmaceutical Sciences , 381 Royal Parade , Parkville , VIC 3052 , Australia
- Department of Chemistry , University of Warwick , Library Road , CV4 4AL Coventry , United Kingdom
| | - Ove J R Gustafsson
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute , University of South Australia , University Boulevard , Mawson Lakes , SA 5095 , Australia
| | - Yanting Xing
- Department of Physics and Astronomy , Clemson University , Clemson , South Carolina 29634 , United States
| | - Juan Hernandez-Fernaud
- Warwick Proteomics Research Technology Platform, School of Life Sciences , University of Warwick , Gibbet Hill Road , CV4 7AL Coventry , United Kingdom
| | - Cleidi Zampronio
- Warwick Proteomics Research Technology Platform, School of Life Sciences , University of Warwick , Gibbet Hill Road , CV4 7AL Coventry , United Kingdom
| | - Aleksandr Kakinen
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology , Monash Institute of Pharmaceutical Sciences , 381 Royal Parade , Parkville , VIC 3052 , Australia
| | - Ava Faridi
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology , Monash Institute of Pharmaceutical Sciences , 381 Royal Parade , Parkville , VIC 3052 , Australia
| | - Feng Ding
- Department of Physics and Astronomy , Clemson University , Clemson , South Carolina 29634 , United States
| | - Paul Wilson
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology , Monash Institute of Pharmaceutical Sciences , 381 Royal Parade , Parkville , VIC 3052 , Australia
- Department of Chemistry , University of Warwick , Library Road , CV4 4AL Coventry , United Kingdom
| | - Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology , Monash Institute of Pharmaceutical Sciences , 381 Royal Parade , Parkville , VIC 3052 , Australia
| | - Thomas P Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology , Monash Institute of Pharmaceutical Sciences , 381 Royal Parade , Parkville , VIC 3052 , Australia
- Department of Chemistry , University of Warwick , Library Road , CV4 4AL Coventry , United Kingdom
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Levels of retinal IAPP are altered in Alzheimer's disease patients and correlate with vascular changes and hippocampal IAPP levels. Neurobiol Aging 2018; 69:94-101. [PMID: 29864717 DOI: 10.1016/j.neurobiolaging.2018.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/06/2018] [Accepted: 05/02/2018] [Indexed: 11/22/2022]
Abstract
Islet amyloid polypeptide (IAPP) forms toxic aggregates in the brain of patients with Alzheimer's disease (AD). Whether IAPP also affects the retina in these patients is still unknown. Levels of IAPP in soluble and insoluble homogenate fractions of retina and hippocampus from AD patients and nondemented controls were analyzed using ELISA. Number of pericytes and vessel length were determined by analysis of immunostained retina and hippocampus. Insoluble retinal fractions of AD patients contained lower levels of unmodified IAPP, whereas soluble retinal fractions contained increased levels of the same. Total IAPP levels and pericyte numbers in retina mirrored corresponding variables in the hippocampus. Moreover, levels of total unmodified IAPP correlated negatively with the vessel length both in retina and hippocampus across the group and positively with pericyte numbers in retina in AD patients. Our studies indicate that changes in brain IAPP are reflected by corresponding levels in the retina. Our results also suggest modification of IAPP as an important event implicated in vascular changes associated with AD.
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59
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Fernández-Gómez I, Sablón-Carrazana M, Bencomo-Martínez A, Domínguez G, Lara-Martínez R, Altamirano-Bustamante NF, Jiménez-García LF, Pasten-Hidalgo K, Castillo-Rodríguez RA, Altamirano P, Marrero SR, Revilla-Monsalve C, Valdés-Sosa P, Salamanca-Gómez F, Garrido-Magaña E, Rodríguez-Tanty C, Altamirano-Bustamante MM. Diabetes Drug Discovery: hIAPP 1-37 Polymorphic Amyloid Structures as Novel Therapeutic Targets. Molecules 2018; 23:molecules23030686. [PMID: 29562662 PMCID: PMC6017868 DOI: 10.3390/molecules23030686] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/20/2018] [Accepted: 02/21/2018] [Indexed: 12/21/2022] Open
Abstract
Human islet amyloid peptide (hIAPP1–37) aggregation is an early step in Diabetes Mellitus. We aimed to evaluate a family of pharmaco-chaperones to act as modulators that provide dynamic interventions and the multi-target capacity (native state, cytotoxic oligomers, protofilaments and fibrils of hIAPP1–37) required to meet the treatment challenges of diabetes. We used a cross-functional approach that combines in silico and in vitro biochemical and biophysical methods to study the hIAPP1–37 aggregation-oligomerization process as to reveal novel potential anti-diabetic drugs. The family of pharmaco-chaperones are modulators of the oligomerization and fibre formation of hIAPP1–37. When they interact with the amino acid in the amyloid-like steric zipper zone, they inhibit and/or delay the aggregation-oligomerization pathway by binding and stabilizing several amyloid structures of hIAPP1–37. Moreover, they can protect cerebellar granule cells (CGC) from the cytotoxicity produced by the hIAPP1–37 oligomers. The modulation of proteostasis by the family of pharmaco-chaperones A–F is a promising potential approach to limit the onset and progression of diabetes and its comorbidities.
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Affiliation(s)
- Isaac Fernández-Gómez
- Unidad de Investigación en Enfermedades Metabólicas, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México 06720, Mexico.
| | | | | | | | - Reyna Lara-Martínez
- Departamento de Biología Celular, Facultad de Ciencias, UNAM, Ciudad de México 04510, Mexico.
| | | | | | - Karina Pasten-Hidalgo
- Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico.
- Cátedras Conacyt, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico.
| | - Rosa Angélica Castillo-Rodríguez
- Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico.
- Cátedras Conacyt, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico.
| | - Perla Altamirano
- Servicio de Medicina Nuclear, Hospital de Especialidades, CMN, La Raza, Instituto Mexicano del Seguro Social, Ciudad de México 06720, Mexico.
| | | | - Cristina Revilla-Monsalve
- Unidad de Investigación en Enfermedades Metabólicas, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México 06720, Mexico.
| | - Peter Valdés-Sosa
- Departamento de Neuroquímica, Centro de Neurociencias de Cuba, Habana 11600, Cuba.
| | - Fabio Salamanca-Gómez
- Coordinación de Investigación en Salud, Instituto Mexicano del Seguro Social, Ciudad de México 06720, Mexico.
| | - Eulalia Garrido-Magaña
- UMAE Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México 06720, Mexico.
| | | | - Myriam M Altamirano-Bustamante
- Unidad de Investigación en Enfermedades Metabólicas, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México 06720, Mexico.
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60
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Rainer PP, Dong P, Sorge M, Fert-Bober J, Holewinski RJ, Wang Y, Foss CA, An SS, Baracca A, Solaini G, Glabe CG, Pomper MG, Van Eyk JE, Tomaselli GF, Paolocci N, Agnetti G. Desmin Phosphorylation Triggers Preamyloid Oligomers Formation and Myocyte Dysfunction in Acquired Heart Failure. Circ Res 2018; 122:e75-e83. [PMID: 29483093 DOI: 10.1161/circresaha.117.312082] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/18/2018] [Accepted: 02/23/2018] [Indexed: 01/28/2023]
Abstract
RATIONALE Disrupted proteostasis is one major pathological trait that heart failure (HF) shares with other organ proteinopathies, such as Alzheimer and Parkinson diseases. Yet, differently from the latter, whether and how cardiac preamyloid oligomers (PAOs) develop in acquired forms of HF is unclear. OBJECTIVE We previously reported a rise in monophosphorylated, aggregate-prone desmin in canine and human HF. We now tested whether monophosphorylated desmin acts as the seed nucleating PAOs formation and determined whether positron emission tomography is able to detect myocardial PAOs in nongenetic HF. METHODS AND RESULTS Here, we first show that toxic cardiac PAOs accumulate in the myocardium of mice subjected to transverse aortic constriction and that PAOs comigrate with the cytoskeletal protein desmin in this well-established model of acquired HF. We confirm this evidence in cardiac extracts from human ischemic and nonischemic HF. We also demonstrate that Ser31 phosphorylated desmin aggregates extensively in cultured cardiomyocytes. Lastly, we were able to detect the in vivo accumulation of cardiac PAOs using positron emission tomography for the first time in acquired HF. CONCLUSIONS Ser31 phosphorylated desmin is a likely candidate seed for the nucleation process leading to cardiac PAOs deposition. Desmin post-translational processing and misfolding constitute a new, attractive avenue for the diagnosis and treatment of the cardiac accumulation of toxic PAOs that can now be measured by positron emission tomography in acquired HF.
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Affiliation(s)
- Peter P Rainer
- From the Division of Cardiology, Medical University of Graz, Austria (P.P.R.)
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
| | - Peihong Dong
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
| | | | - Justyna Fert-Bober
- Cedars-Sinai Medical Center, Beverly-Hills, CA (J.F.-B., R.J.H., J.E.V.E.)
| | | | - Yuchuan Wang
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
| | - Catherine A Foss
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
| | - Steven S An
- Johns Hopkins School of Public Health, Baltimore, MD (S.S.A.)
| | - Alessandra Baracca
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy (A.B., G.S., G.A.)
| | - Giancarlo Solaini
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy (A.B., G.S., G.A.)
| | | | - Martin G Pomper
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
| | - Jennifer E Van Eyk
- Cedars-Sinai Medical Center, Beverly-Hills, CA (J.F.-B., R.J.H., J.E.V.E.)
| | - Gordon F Tomaselli
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
| | - Nazareno Paolocci
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
- University of Perugia, Italy (N.P.)
| | - Giulio Agnetti
- Johns Hopkins School of Medicine, Baltimore, MD (P.P.R., P.D., Y.W., C.A.F., M.G.P., G.F.T., N.P., G.A.)
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy (A.B., G.S., G.A.)
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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] [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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Abedini A, Cao P, Plesner A, Zhang J, He M, Derk J, Patil SA, Rosario R, Lonier J, Song F, Koh H, Li H, Raleigh DP, Schmidt AM. RAGE binds preamyloid IAPP intermediates and mediates pancreatic β cell proteotoxicity. J Clin Invest 2018; 128:682-698. [PMID: 29337308 DOI: 10.1172/jci85210] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 11/17/2017] [Indexed: 01/04/2023] Open
Abstract
Islet amyloidosis is characterized by the aberrant accumulation of islet amyloid polypeptide (IAPP) in pancreatic islets, resulting in β cell toxicity, which exacerbates type 2 diabetes and islet transplant failure. It is not fully clear how IAPP induces cellular stress or how IAPP-induced toxicity can be prevented or treated. We recently defined the properties of toxic IAPP species. Here, we have identified a receptor-mediated mechanism of islet amyloidosis-induced proteotoxicity. In human diabetic pancreas and in cellular and mouse models of islet amyloidosis, increased expression of the receptor for advanced glycation endproducts (RAGE) correlated with human IAPP-induced (h-IAPP-induced) β cell and islet inflammation, toxicity, and apoptosis. RAGE selectively bound toxic intermediates, but not nontoxic forms of h-IAPP, including amyloid fibrils. The isolated extracellular ligand-binding domains of soluble RAGE (sRAGE) blocked both h-IAPP toxicity and amyloid formation. Inhibition of the interaction between h-IAPP and RAGE by sRAGE, RAGE-blocking antibodies, or genetic RAGE deletion protected pancreatic islets, β cells, and smooth muscle cells from h-IAPP-induced inflammation and metabolic dysfunction. sRAGE-treated h-IAPP Tg mice were protected from amyloid deposition, loss of β cell area, β cell inflammation, stress, apoptosis, and glucose intolerance. These findings establish RAGE as a mediator of IAPP-induced toxicity and suggest that targeting the IAPP/RAGE axis is a potential strategy to mitigate this source of β cell dysfunction in metabolic disease.
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Affiliation(s)
- Andisheh Abedini
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | | | - Jinghua Zhang
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Meilun He
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Julia Derk
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Sachi A Patil
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Rosa Rosario
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Jacqueline Lonier
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Fei Song
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
| | - Hyunwook Koh
- Division of Biostatistics, Department of Population Health, NYU School of Medicine, New York, New York, USA
| | - Huilin Li
- Division of Biostatistics, Department of Population Health, NYU School of Medicine, New York, New York, USA
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York, USA
| | - Ann Marie Schmidt
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, NYU School of Medicine, New York, New York, USA
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63
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Avila-Vazquez MF, Altamirano-Bustamante NF, Altamirano-Bustamante MM. Amyloid Biomarkers in Conformational Diseases at Face Value: A Systematic Review. Molecules 2017; 23:molecules23010079. [PMID: 29286329 PMCID: PMC6017595 DOI: 10.3390/molecules23010079] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/03/2017] [Accepted: 10/11/2017] [Indexed: 12/20/2022] Open
Abstract
Conformational diseases represent a new aspect of proteomic medicine where diagnostic and therapeutic paradigms are evolving. In this context, the early biomarkers for target cell failure (neurons, β-cells, etc.) represent a challenge to translational medicine and play a multidimensional role as biomarkers and potential therapeutic targets. This systematic review, which follows the PICO and Prisma methods, analyses this new-fangled multidimensionality, its strengths and limitations, and presents the future possibilities it opens up. The nuclear diagnosis methods are immunoassays: ELISA, immunodot, western blot, etc., while the therapeutic approach is focused on pharmaco- and molecular chaperones.
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Affiliation(s)
- Maria Fernanda Avila-Vazquez
- Unidad de Investigación en Enfermedades Metabólicas, Centro Médico Nacional Siglo XXI, IMSS, Mexico City 06720, Mexico.
- Health Department, Universidad Iberoamericana, Mexico City 01219, Mexico.
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64
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Pilkington E, Lai M, Ge X, Stanley WJ, Wang B, Wang M, Kakinen A, Sani MA, Whittaker MR, Gurzov EN, Ding F, Quinn JF, Davis TP, Ke PC. Star Polymers Reduce Islet Amyloid Polypeptide Toxicity via Accelerated Amyloid Aggregation. Biomacromolecules 2017; 18:4249-4260. [PMID: 29035554 PMCID: PMC5729549 DOI: 10.1021/acs.biomac.7b01301] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/13/2017] [Indexed: 01/20/2023]
Abstract
Protein aggregation into amyloid fibrils is a ubiquitous phenomenon across the spectrum of neurodegenerative disorders and type 2 diabetes. A common strategy against amyloidogenesis is to minimize the populations of toxic oligomers and protofibrils by inhibiting protein aggregation with small molecules or nanoparticles. However, melanin synthesis in nature is realized by accelerated protein fibrillation to circumvent accumulation of toxic intermediates. Accordingly, we designed and demonstrated the use of star-shaped poly(2-hydroxyethyl acrylate) (PHEA) nanostructures for promoting aggregation while ameliorating the toxicity of human islet amyloid polypeptide (IAPP), the peptide involved in glycemic control and the pathology of type 2 diabetes. The binding of PHEA elevated the β-sheet content in IAPP aggregates while rendering a new morphology of "stelliform" amyloids originating from the polymers. Atomistic molecular dynamics simulations revealed that the PHEA arms served as rodlike scaffolds for IAPP binding and subsequently accelerated IAPP aggregation by increased local peptide concentration. The tertiary structure of the star nanoparticles was found to be essential for driving the specific interactions required to impel the accelerated IAPP aggregation. This study sheds new light on the structure-toxicity relationship of IAPP and points to the potential of exploiting star polymers as a new class of therapeutic agents against amyloidogenesis.
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Affiliation(s)
- Emily
H. Pilkington
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - May Lai
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Xinwei Ge
- Department
of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - William J. Stanley
- St
Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065, Australia
- Department
of Medicine, St. Vincent’s Hospital, The University of Melbourne, Melbourne, Australia
| | - Bo Wang
- Department
of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - Miaoyi Wang
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Aleksandr Kakinen
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Marc-Antonie Sani
- School of
Chemistry, Bio21 Institute, The University
of Melbourne, 30 Flemington
Rd, Parkville, Victoria 3010, Australia
| | - Michael R. Whittaker
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Esteban N. Gurzov
- St
Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065, Australia
- Department
of Medicine, St. Vincent’s Hospital, The University of Melbourne, Melbourne, Australia
| | - Feng Ding
- Department
of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - John F. Quinn
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Thomas P. Davis
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
- Department
of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom
| | - Pu Chun Ke
- ARC
Centre of Excellence in Convergent Bio-Nano Science and Technology,
Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
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65
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Javed I, Sun Y, Adamcik J, Wang B, Kakinen A, Pilkington EH, Ding F, Mezzenga R, Davis TP, Ke PC. Cofibrillization of Pathogenic and Functional Amyloid Proteins with Gold Nanoparticles against Amyloidogenesis. Biomacromolecules 2017; 18:4316-4322. [PMID: 29095600 PMCID: PMC5901968 DOI: 10.1021/acs.biomac.7b01359] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Biomimetic nanocomposites and scaffolds hold the key to a wide range of biomedical applications. Here we show, for the first time, a facile scheme of cofibrillizing pathogenic and functional amyloid fibrils via gold nanoparticles (AuNPs) and their applications against amyloidogenesis. This scheme was realized by β-sheet stacking between human islet amyloid polypeptide (IAPP) and the β-lactoglobulin "corona" of the AuNPs, as revealed by transmission electron microscopy, 3D atomic force microscopy, circular dichroism spectroscopy, and molecular dynamics simulations. The biomimetic AuNPs eliminated IAPP toxicity, enabled X-ray destruction of IAPP amyloids, and allowed dark-field imaging of pathogenic amyloids and their immunogenic response by human T cells. In addition to providing a viable new nanotechnology against amyloidogenesis, this study has implications for understanding the in vivo cross-talk between amyloid proteins of different pathologies.
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Affiliation(s)
- Ibrahim Javed
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Yunxiang Sun
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Jozef Adamcik
- Food & Soft Materials, Department of Health Science & Technology, ETH Zurich, Schmelzbergstrasse 9, LFO, E23, 8092, Zurich, Switzerland
| | - Bo Wang
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Aleksandr Kakinen
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Emily H. Pilkington
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Raffaele Mezzenga
- Food & Soft Materials, Department of Health Science & Technology, ETH Zurich, Schmelzbergstrasse 9, LFO, E23, 8092, Zurich, Switzerland
| | - Thomas P. Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, United Kingdom
| | - Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
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66
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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] [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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67
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Neth BJ, Craft S. Insulin Resistance and Alzheimer's Disease: Bioenergetic Linkages. Front Aging Neurosci 2017; 9:345. [PMID: 29163128 PMCID: PMC5671587 DOI: 10.3389/fnagi.2017.00345] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/13/2017] [Indexed: 12/14/2022] Open
Abstract
Metabolic dysfunction is a well-established feature of Alzheimer's disease (AD), evidenced by brain glucose hypometabolism that can be observed potentially decades prior to the development of AD symptoms. Furthermore, there is mounting support for an association between metabolic disease and the development of AD and related dementias. Individuals with insulin resistance, type 2 diabetes mellitus (T2D), hyperlipidemia, obesity, or other metabolic disease may have increased risk for the development of AD and similar conditions, such as vascular dementia. This association may in part be due to the systemic mitochondrial dysfunction that is common to these pathologies. Accumulating evidence suggests that mitochondrial dysfunction is a significant feature of AD and may play a fundamental role in its pathogenesis. In fact, aging itself presents a unique challenge due to inherent mitochondrial dysfunction and prevalence of chronic metabolic disease. Despite the progress made in understanding the pathogenesis of AD and in the development of potential therapies, at present we remain without a disease-modifying treatment. In this review, we will discuss insulin resistance as a contributing factor to the pathogenesis of AD, as well as the metabolic and bioenergetic disruptions linking insulin resistance and AD. We will also focus on potential neuroimaging tools for the study of the metabolic dysfunction commonly seen in AD with hopes of developing therapeutic and preventative targets.
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Affiliation(s)
- Bryan J Neth
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Suzanne Craft
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States
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68
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Amylin and diabetic cardiomyopathy - amylin-induced sarcolemmal Ca 2+ leak is independent of diabetic remodeling of myocardium. Biochim Biophys Acta Mol Basis Dis 2017; 1864:1923-1930. [PMID: 29066284 DOI: 10.1016/j.bbadis.2017.10.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/06/2017] [Accepted: 10/16/2017] [Indexed: 02/08/2023]
Abstract
Amylin is a pancreatic β-cell hormone co-secreted with insulin, plays a role in normal glucose homeostasis, and forms amyloid in the pancreatic islets of individuals with type-2 diabetes. Aggregated amylin is also found in blood and extra-pancreatic tissues, including myocardium. Myocardial amylin accumulation is associated with myocyte Ca2+ dysregulation in diabetic rats expressing human amylin. Whether deposition of amylin in the heart is a consequence of or a contributor to diabetic cardiomyopathy remains unknown. We used amylin knockout (AKO) mice intravenously infused with either human amylin (i.e, the aggregated form) or non-amyloidogenic (i.e., monomeric) rodent amylin to test the hypothesis that aggregated amylin accumulates in the heart in the absence of diabetes. AKO mice infused with human amylin, but not rodent amylin, showed amylin deposits in the myocardium. Cardiac amylin level was larger in males compared to females. Sarcolemmal Ca2+ leak and Ca2+ transients were increased in myocytes isolated from males infused with human amylin while no significant changes occurred in either females injected with human amylin or in rat amylin-infused mice. In isolated cardiac myocytes, the amylin receptor antagonist AC-187 did not effectively block the interaction of amylin with the sarcolemma. In conclusion, circulating aggregated amylin accumulates preferentially in male vs. female hearts and its effects on myocyte Ca2+ cycling do not require diabetic remodeling of the myocardium. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.
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69
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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] [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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70
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Amylin Receptor: A Potential Therapeutic Target for Alzheimer's Disease. Trends Mol Med 2017; 23:709-720. [PMID: 28694141 DOI: 10.1016/j.molmed.2017.06.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/08/2017] [Accepted: 06/14/2017] [Indexed: 01/29/2023]
Abstract
Alzheimer'sdisease (AD) is a progressive neurodegenerative disorder, characterized by senile plaques constituting extracellular deposits of β-amyloid (Aβ) fibrils. Since Aβ accumulation in the brain is considered an early event preceding, by decades, cognitive dysfunction, disease-modifying treatments are aimed at facilitating clearance of this protein from the brain or ameliorating its toxic effects. Recent studies have identified the amylin receptor as a capable mediator of the deleterious actions of Aβ and furthermore, administration of amylin receptor-based peptides has been shown to improve spatial memory and learning in transgenic mouse models of AD. Here, by discussing available evidence, we posit that the amylin receptor could be considered a potential therapeutic target for AD, and present the rationale for using amylin receptor antagonists to treat this debilitating condition.
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71
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Young LM, Tu LH, Raleigh DP, Ashcroft AE, Radford SE. Understanding co-polymerization in amyloid formation by direct observation of mixed oligomers. Chem Sci 2017; 8:5030-5040. [PMID: 28970890 PMCID: PMC5613229 DOI: 10.1039/c7sc00620a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 05/03/2017] [Indexed: 12/15/2022] Open
Abstract
Although amyloid assembly in vitro is commonly investigated using single protein sequences, fibril formation in vivo can be more heterogeneous, involving co-assembly of proteins of different length, sequence and/or post-translational modifications. Emerging evidence suggests that co-polymerization can alter the rate and/or mechanism of aggregation and can contribute to pathogenicity. Electrospray ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS) is uniquely suited to the study of these heterogeneous ensembles. Here, ESI-IMS-MS combined with analysis of fibrillation rates using thioflavin T (ThT) fluorescence, is used to track the course of aggregation of variants of islet-amyloid polypeptide (IAPP) in isolation and in pairwise mixtures. We identify a sub-population of extended monomers as the key precursors of amyloid assembly, and reveal that the fastest aggregating sequence in peptide mixtures determines the lag time of fibrillation, despite being unable to cross-seed polymerization. The results demonstrate that co-polymerization of IAPP sequences radically alters the rate of amyloid assembly by altering the conformational properties of the mixed oligomers that form.
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Affiliation(s)
- Lydia M Young
- Astbury Centre for Structural Molecular Biology , School of Molecular and Cellular Biology , University of Leeds , Leeds LS2 9JT , UK .
| | - Ling-Hsien Tu
- Department of Chemistry , Stony Brook University , Stony Brook , New York 11794-3400 , USA
- Genomics Research Center , Academia Sinica , 128 Academia , Taipei 11529 , Taiwan
| | - Daniel P Raleigh
- Department of Chemistry , Stony Brook University , Stony Brook , New York 11794-3400 , USA
| | - Alison E Ashcroft
- Astbury Centre for Structural Molecular Biology , School of Molecular and Cellular Biology , University of Leeds , Leeds LS2 9JT , UK .
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology , School of Molecular and Cellular Biology , University of Leeds , Leeds LS2 9JT , UK .
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72
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Troncone L, Luciani M, Coggins M, Wilker EH, Ho CY, Codispoti KE, Frosch MP, Kayed R, Del Monte F. Aβ Amyloid Pathology Affects the Hearts of Patients With Alzheimer's Disease: Mind the Heart. J Am Coll Cardiol 2017; 68:2395-2407. [PMID: 27908343 DOI: 10.1016/j.jacc.2016.08.073] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/08/2016] [Accepted: 08/31/2016] [Indexed: 12/21/2022]
Abstract
BACKGROUND Individually, heart failure (HF) and Alzheimer's disease (AD) are severe threats to population health, and their potential coexistence is an alarming prospect. In addition to sharing analogous epidemiological and genetic profiles, biochemical characteristics, and common triggers, the authors recently recognized common molecular and pathological features between the 2 conditions. Whereas cognitive impairment has been linked to HF through perfusion defects, angiopathy, and inflammation, whether patients with AD present with myocardial dysfunction, and if the 2 conditions bear a common pathogenesis as neglected siblings are unknown. OBJECTIVES Here, the authors investigated whether amyloid beta (Aβ) protein aggregates are present in the hearts of patients with a primary diagnosis of AD, affecting myocardial function. METHODS The authors examined myocardial function in a retrospective cross-sectional study from a cohort of AD patients and age-matched controls. Imaging and proteomics approaches were used to identify and quantify Aβ deposits in AD heart and brain specimens compared with controls. Cell shortening and calcium transients were measured on isolated adult cardiomyocytes. RESULTS Echocardiographic measurements of myocardial function suggest that patients with AD present with an anticipated diastolic dysfunction. As in the brain, Aβ40 and Aβ42 are present in the heart, and their expression is increased in AD. CONCLUSIONS Here, the authors provide the first report of the presence of compromised myocardial function and intramyocardial deposits of Aβ in AD patients. The findings depict a novel biological framework in which AD may be viewed either as a systemic disease or as a metastatic disorder leading to heart, and possibly multiorgan failure. AD and HF are both debilitating and life-threatening conditions, affecting enormous patient populations. Our findings underline a previously dismissed problem of a magnitude that will require new diagnostic approaches and treatments for brain and heart disease, and their combination.
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Affiliation(s)
- Luca Troncone
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Marco Luciani
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Matthew Coggins
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Elissa H Wilker
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Cheng-Ying Ho
- Department of Neurology, Johns Hopkins Hospital, Baltimore, Maryland
| | | | - Matthew P Frosch
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Rakez Kayed
- Department of Neurology, University of Texas Medical Branch Health, Galveston, Texas
| | - Federica Del Monte
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Division of Cardiology Massachusetts General Hospital, Boston, Massachusetts.
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73
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Abstract
The incidence and prevalence of cardiac diseases, which are the main cause of death worldwide, are likely to increase because of population ageing. Prevailing theories about the mechanisms of ageing feature the gradual derailment of cellular protein homeostasis (proteostasis) and loss of protein quality control as central factors. In the heart, loss of protein patency, owing to flaws in genetically-determined design or because of environmentally-induced 'wear and tear', can overwhelm protein quality control, thereby triggering derailment of proteostasis and contributing to cardiac ageing. Failure of protein quality control involves impairment of chaperones, ubiquitin-proteosomal systems, autophagy, and loss of sarcomeric and cytoskeletal proteins, all of which relate to induction of cardiomyocyte senescence. Targeting protein quality control to maintain cardiac proteostasis offers a novel therapeutic strategy to promote cardiac health and combat cardiac disease. Currently marketed drugs are available to explore this concept in the clinical setting.
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Affiliation(s)
- Robert H Henning
- Department of Clinical Pharmacy and Pharmacology, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - Bianca J J M Brundel
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, De Boelelaan 1117, 1081 HZ Amsterdam, The Netherlands
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74
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Mukherjee A, Soto C. Prion-Like Protein Aggregates and Type 2 Diabetes. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a024315. [PMID: 28159831 DOI: 10.1101/cshperspect.a024315] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes (T2D) is a highly prevalent metabolic disease characterized by chronic insulin resistance and β-cell dysfunction and loss, leading to impaired insulin release and hyperglycemia. Although the mechanism responsible for β-cell dysfunction and death is not completely understood, recent findings suggest that the accumulation of misfolded aggregates of the islet amyloid polypeptide (IAPP) in the islets of Langerhans may play an important role in pancreatic damage. Misfolding and aggregation of diverse proteins and their accumulation as amyloid in different organs is the hallmark feature in a group of chronic, degenerative diseases termed protein misfolding disorders (PMDs). PMDs include highly prevalent human illnesses such as Alzheimer's and Parkinson's disease, as well as more than 25 rarer disorders. Among them, prion diseases are unique because the pathology can be transmitted by a proteinaceous infectious agent, termed a prion, which induces disease by propagating protein misfolding and aggregation. This phenomenon has a striking resemblance to the process of protein misfolding and aggregation in all of the PMDs, suggesting that misfolded aggregates have an intrinsic potential to be transmissible. Indeed, recent studies have shown that the pathological hallmarks of various PMDs can be induced in vivo under experimental conditions by inoculating tissue extracts containing protein aggregates into animal models. In this review, we describe our current understanding of the molecular mechanism underlying the prion-like transmission of protein aggregates and its possible role in T2D.
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Affiliation(s)
- Abhisek Mukherjee
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030
| | - Claudio Soto
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Health Science Center, McGovern Medical School, Houston, Texas 77030
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75
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de Matos AM, de Macedo MP, Rauter AP. Bridging Type 2 Diabetes and Alzheimer's Disease: Assembling the Puzzle Pieces in the Quest for the Molecules With Therapeutic and Preventive Potential. Med Res Rev 2017; 38:261-324. [PMID: 28422298 DOI: 10.1002/med.21440] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/18/2017] [Accepted: 02/14/2017] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes (T2D) and Alzheimer's disease (AD) are two age-related amyloid diseases that affect millions of people worldwide. Broadly supported by epidemiological data, the higher incidence of AD among type 2 diabetic patients led to the recognition of T2D as a tangible risk factor for the development of AD. Indeed, there is now growing evidence on brain structural and functional abnormalities arising from brain insulin resistance and deficiency, ultimately highlighting the need for new approaches capable of preventing the development of AD in type 2 diabetic patients. This review provides an update on overlapping pathophysiological mechanisms and pathways in T2D and AD, such as amyloidogenic events, oxidative stress, endothelial dysfunction, aberrant enzymatic activity, and even shared genetic background. These events will be presented as puzzle pieces put together, thus establishing potential therapeutic targets for drug discovery and development against T2D and diabetes-induced cognitive decline-a heavyweight contributor to the increasing incidence of dementia in developed countries. Hoping to pave the way in this direction, we will present some of the most promising and well-studied drug leads with potential against both pathologies, including their respective bioactivity reports, mechanisms of action, and structure-activity relationships.
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Affiliation(s)
- Ana Marta de Matos
- Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016, Lisbon, Portugal.,CEDOC Chronic Diseases, Nova Medical School, Rua Câmara Pestana n 6, 6-A, Ed. CEDOC II, 1150-082, Lisbon, Portugal
| | - Maria Paula de Macedo
- CEDOC Chronic Diseases, Nova Medical School, Rua Câmara Pestana n 6, 6-A, Ed. CEDOC II, 1150-082, Lisbon, Portugal
| | - Amélia Pilar Rauter
- Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016, Lisbon, Portugal
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76
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Sapp V, Jain M, Liao R. Viewing Extrinsic Proteotoxic Stress Through the Lens of Amyloid Cardiomyopathy. Physiology (Bethesda) 2017; 31:294-9. [PMID: 27252164 DOI: 10.1152/physiol.00047.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Proteotoxicity refers to toxic stress caused by misfolded proteins of extrinsic or intrinsic origin and plays an integral role in the pathogenesis of cardiovascular diseases. Herein, we provide an overview of the current understanding of mechanisms underlying proteotoxicity and its contribution in the pathogenesis of amyloid cardiomyopathy.
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Affiliation(s)
- Valerie Sapp
- Departments of Medicine & Pharmacology, University of California San Diego, San Diego, California; and
| | - Mohit Jain
- Departments of Medicine & Pharmacology, University of California San Diego, San Diego, California; and
| | - Ronglih Liao
- Division of Genetics and Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
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77
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Evans TD, Sergin I, Zhang X, Razani B. Target acquired: Selective autophagy in cardiometabolic disease. Sci Signal 2017; 10:eaag2298. [PMID: 28246200 PMCID: PMC5451512 DOI: 10.1126/scisignal.aag2298] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The accumulation of damaged or excess proteins and organelles is a defining feature of metabolic disease in nearly every tissue. Thus, a central challenge in maintaining metabolic homeostasis is the identification, sequestration, and degradation of these cellular components, including protein aggregates, mitochondria, peroxisomes, inflammasomes, and lipid droplets. A primary route through which this challenge is met is selective autophagy, the targeting of specific cellular cargo for autophagic compartmentalization and lysosomal degradation. In addition to its roles in degradation, selective autophagy is emerging as an integral component of inflammatory and metabolic signaling cascades. In this Review, we focus on emerging evidence and key questions about the role of selective autophagy in the cell biology and pathophysiology of metabolic diseases such as obesity, diabetes, atherosclerosis, and steatohepatitis. Essential players in these processes are the selective autophagy receptors, defined broadly as adapter proteins that both recognize cargo and target it to the autophagosome. Additional domains within these receptors may allow integration of information about autophagic flux with critical regulators of cellular metabolism and inflammation. Details regarding the precise receptors involved, such as p62 and NBR1, and their predominant interacting partners are just beginning to be defined. Overall, we anticipate that the continued study of selective autophagy will prove to be informative in understanding the pathogenesis of metabolic diseases and to provide previously unrecognized therapeutic targets.
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Affiliation(s)
- Trent D Evans
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ismail Sergin
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xiangyu Zhang
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Babak Razani
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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78
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Zhang X, St Clair JR, London E, Raleigh DP. Islet Amyloid Polypeptide Membrane Interactions: Effects of Membrane Composition. Biochemistry 2017; 56:376-390. [PMID: 28054763 DOI: 10.1021/acs.biochem.6b01016] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloid formation by islet amyloid polypeptide (IAPP) contributes to β-cell dysfunction in type 2 diabetes. Perturbation of the β-cell membrane may contribute to IAPP-induced toxicity. We examine the effects of lipid composition, salt, and buffer on IAPP amyloid formation and on the ability of IAPP to induce leakage of model membranes. Even low levels of anionic lipids promote amyloid formation and membrane permeabilization. Increasing the percentage of the anionic lipids, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS) or 1,2-dioleoyl-sn-glycero-3-phospho(1'-rac-glycerol), enhances the rate of amyloid formation and increases the level of membrane permeabilization. The choice of zwitterionic lipid has no noticeable effect on membrane-catalyzed amyloid formation but in most cases affects leakage, which tends to decrease in the following order: 1,2-dioleoyl-sn-glycero-3-phosphocholine > 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine > sphingomyelin. Uncharged lipids that increase the level of membrane order weaken the ability of IAPP to induce leakage. Leakage is due predominately to pore formation rather than complete disruption of the vesicles under the conditions used in these studies. Cholesterol at or below physiological levels significantly reduces the rate of vesicle-catalyzed IAPP amyloid formation and decreases the susceptibility to IAPP-induced leakage. The effects of cholesterol on amyloid formation are masked by 25 mol % POPS. Overall, there is a strong inverse correlation between the time to form amyloid and the extent of vesicle leakage. NaCl reduces the rate of membrane-catalyzed amyloid formation by anionic vesicles, but accelerates amyloid formation in solution. The implications for IAPP membrane interactions are discussed, as is the possibility that the loss of phosphatidylserine asymmetry enhances IAPP amyloid formation and membrane damage in vivo via a positive feedback loop.
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Affiliation(s)
- Xiaoxue Zhang
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States
| | - Johnna R St Clair
- Department of Biochemistry and Cell Biology, Stony Brook University , Stony Brook, New York 11794-5215, United States
| | - Erwin London
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.,Department of Biochemistry and Cell Biology, Stony Brook University , Stony Brook, New York 11794-5215, United States
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.,Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York 11794-5215, United States
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79
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Trivedi PC, Bartlett JJ, Perez LJ, Brunt KR, Legare JF, Hassan A, Kienesberger PC, Pulinilkunnil T. Glucolipotoxicity diminishes cardiomyocyte TFEB and inhibits lysosomal autophagy during obesity and diabetes. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1893-1910. [PMID: 27620487 DOI: 10.1016/j.bbalip.2016.09.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 09/05/2016] [Accepted: 09/07/2016] [Indexed: 01/07/2023]
Abstract
Impaired cardiac metabolism in the obese and diabetic heart leads to glucolipotoxicity and ensuing cardiomyopathy. Glucolipotoxicity causes cardiomyocyte injury by increasing energy insufficiency, impairing proteasomal-mediated protein degradation and inducing apoptosis. Proteasome-evading proteins are degraded by autophagy in the lysosome, whose metabolism and function are regulated by master regulator transcription factor EB (TFEB). Limited studies have examined the impact of glucolipotoxicity on intra-lysosomal signaling proteins and their regulators. By utilizing a mouse model of diet-induced obesity, type-1 diabetes (Akita) and ex-vivo model of glucolipotoxicity (H9C2 cells and NRCM, neonatal rat cardiomyocyte), we examined whether glucolipotoxicity negatively targets TFEB and lysosomal proteins to dysregulate autophagy and cause cardiac injury. Despite differential effects of obesity and diabetes on LC3B-II, expression of proteins facilitating autophagosomal clearance such as TFEB, LAMP-2A, Hsc70 and Hsp90 were decreased in the obese and diabetic heart. In-vivo data was recapitulated in H9C2 and NRCM cells, which exhibited impaired autophagic flux and reduced TFEB content when exposed to a glucolipotoxic milieu. Notably, overloading myocytes with a saturated fatty acid (palmitate) but not an unsaturated fatty acid (oleate) depleted cellular TFEB and suppressed autophagy, suggesting a fatty acid specific regulation of TFEB and autophagy in the cardiomyocyte. The effect of glucolipotoxicity to reduce TFEB content was also confirmed in heart tissue from patients with Class-I obesity. Therefore, during glucolipotoxicity, suppression of lysosomal autophagy was associated with reduced lysosomal content, decreased cathepsin-B activity and diminished cellular TFEB content likely rendering myocytes susceptible to cardiac injury.
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Affiliation(s)
- Purvi C Trivedi
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Jordan J Bartlett
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Lester J Perez
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Keith R Brunt
- Deparment of Pharmacology, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Jean Francois Legare
- Department of Surgery, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Ansar Hassan
- Department of Surgery, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Petra C Kienesberger
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada
| | - Thomas Pulinilkunnil
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John E2L4L5, New Brunswick, Canada.
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80
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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] [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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81
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Abedini A, Plesner A, Cao P, Ridgway Z, Zhang J, Tu LH, Middleton CT, Chao B, Sartori DJ, Meng F, Wang H, Wong AG, Zanni MT, Verchere CB, Raleigh DP, Schmidt AM. Time-resolved studies define the nature of toxic IAPP intermediates, providing insight for anti-amyloidosis therapeutics. eLife 2016; 5. [PMID: 27213520 PMCID: PMC4940161 DOI: 10.7554/elife.12977] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 05/20/2016] [Indexed: 01/04/2023] Open
Abstract
Islet amyloidosis by IAPP contributes to pancreatic β-cell death in diabetes, but the nature of toxic IAPP species remains elusive. Using concurrent time-resolved biophysical and biological measurements, we define the toxic species produced during IAPP amyloid formation and link their properties to induction of rat INS-1 β-cell and murine islet toxicity. These globally flexible, low order oligomers upregulate pro-inflammatory markers and induce reactive oxygen species. They do not bind 1-anilnonaphthalene-8-sulphonic acid and lack extensive β-sheet structure. Aromatic interactions modulate, but are not required for toxicity. Not all IAPP oligomers are toxic; toxicity depends on their partially structured conformational states. Some anti-amyloid agents paradoxically prolong cytotoxicity by prolonging the lifetime of the toxic species. The data highlight the distinguishing properties of toxic IAPP oligomers and the common features that they share with toxic species reported for other amyloidogenic polypeptides, providing information for rational drug design to treat IAPP induced β-cell death. DOI:http://dx.doi.org/10.7554/eLife.12977.001
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Affiliation(s)
- Andisheh Abedini
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University School of Medicine, New York, United States
| | - Annette Plesner
- Child and Family Research Institute, Department of Pathology and Laboratory Medicine and Department of Surgery, University of British Columbia, Vancouver, Canada
| | - Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Zachary Ridgway
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Jinghua Zhang
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University School of Medicine, New York, United States
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Chris T Middleton
- Department of Chemistry, University of Wisconsin-Madison, Madison, United States
| | - Brian Chao
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University School of Medicine, New York, United States
| | - Daniel J Sartori
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University School of Medicine, New York, United States
| | - Fanling Meng
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Hui Wang
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Amy G Wong
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison, Madison, United States
| | - C Bruce Verchere
- Child and Family Research Institute, Department of Pathology and Laboratory Medicine and Department of Surgery, University of British Columbia, Vancouver, Canada
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, United States
| | - Ann Marie Schmidt
- Diabetes Research Program, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University School of Medicine, New York, United States
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82
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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] [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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83
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XiaoTian L, QiNan W, XiaGuang G, WuQuan D, Bing C, ZiWen L. Exenatide Activates the APPL1-AMPK-PPARα Axis to Prevent Diabetic Cardiomyocyte Apoptosis. J Diabetes Res 2015; 2016:4219735. [PMID: 26759813 PMCID: PMC4677202 DOI: 10.1155/2016/4219735] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 06/07/2015] [Accepted: 06/10/2015] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVE To investigate the effect and mechanism of the exenatide on diabetic cardiomyopathy. METHODS Rats were divided into control group, diabetes group (D), diabetes treated with insulin (DI) group, and diabetes treat with exenatide (DE) group. We detected apoptosis rate by TUNEL, the adiponectin and high molecular weight adiponectin (HMW-adiponectin) by ELISA, and the expression of APPL1, p-AMPK/T-AMPK, PPARα, and NF-κB by immunohistochemistry and western blotting. RESULTS Compared with the D group, the apoptosis in the Control and DE groups was decreased (P < 0.05); the adiponectin and HMW-adiponectin were increased (P < 0.05); the APPL1, p-AMPK/T-AMPK, PPARα, and LV -dP/dt were increased (P < 0.05); and the NF-κB, GRP78, and LVEDP were decreased (P < 0.05). Compared with DE group, the glucose levels in the DI group were similar (P < 0.05); the apoptosis and LVEDP were increased; the APPL1, p-AMPK/T-AMPK, PPARα, and LV -dP/dt were decreased (P < 0.05); the NF-κB and GRP78 were increased (P < 0.05); the adiponectin and HMW-adiponectin were significantly decreased (P < 0.05). CONCLUSION Our model of diabetic cardiomyopathy was constructed successfully. After being treated with exenatide, the adiponectin and HMW-adiponectin and the APPL1-AMPK-PPARα axis were increased, the NF-κB and the apoptosis were decreased, the cardiac function of the diabetic rats was improved, and these effects were independent of glucose control.
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Affiliation(s)
- Lei XiaoTian
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chongqing 400038, China
| | - Wu QiNan
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chongqing 400038, China
| | - Gan XiaGuang
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chongqing 400038, China
| | - Deng WuQuan
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chongqing 400038, China
| | - Chen Bing
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chongqing 400038, China
| | - Liang ZiWen
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chongqing 400038, China
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Akter R, Cao P, Noor H, Ridgway Z, Tu LH, Wang H, Wong AG, Zhang X, Abedini A, Schmidt AM, Raleigh DP. Islet Amyloid Polypeptide: Structure, Function, and Pathophysiology. J Diabetes Res 2015; 2016:2798269. [PMID: 26649319 PMCID: PMC4662979 DOI: 10.1155/2016/2798269] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/24/2015] [Indexed: 01/29/2023] Open
Abstract
The hormone islet amyloid polypeptide (IAPP, or amylin) plays a role in glucose homeostasis but aggregates to form islet amyloid in type-2 diabetes. Islet amyloid formation contributes to β-cell dysfunction and death in the disease and to the failure of islet transplants. Recent work suggests a role for IAPP aggregation in cardiovascular complications of type-2 diabetes and hints at a possible role in type-1 diabetes. The mechanisms of IAPP amyloid formation in vivo or in vitro are not understood and the mechanisms of IAPP induced β-cell death are not fully defined. Activation of the inflammasome, defects in autophagy, ER stress, generation of reactive oxygen species, membrane disruption, and receptor mediated mechanisms have all been proposed to play a role. Open questions in the field include the relative importance of the various mechanisms of β-cell death, the relevance of reductionist biophysical studies to the situation in vivo, the molecular mechanism of amyloid formation in vitro and in vivo, the factors which trigger amyloid formation in type-2 diabetes, the potential role of IAPP in type-1 diabetes, the development of clinically relevant inhibitors of islet amyloidosis toxicity, and the design of soluble, bioactive variants of IAPP for use as adjuncts to insulin therapy.
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Affiliation(s)
- Rehana Akter
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Harris Noor
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Zachary Ridgway
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Hui Wang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Amy G. Wong
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Xiaoxue Zhang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Andisheh Abedini
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Ann Marie Schmidt
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
- Research Department of Structural and Molecule Biology, University College London, Gower Street, London WC1E 6BT, UK
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85
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Ly H, Despa F. Hyperamylinemia as a risk factor for accelerated cognitive decline in diabetes. Expert Rev Proteomics 2015; 12:575-7. [PMID: 26503000 DOI: 10.1586/14789450.2015.1104251] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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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86
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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] [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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87
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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] [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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88
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Mukherjee A, Morales-Scheihing D, Butler PC, Soto C. Type 2 diabetes as a protein misfolding disease. Trends Mol Med 2015; 21:439-49. [PMID: 25998900 DOI: 10.1016/j.molmed.2015.04.005] [Citation(s) in RCA: 216] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/16/2015] [Accepted: 04/22/2015] [Indexed: 12/12/2022]
Abstract
Type 2 diabetes (T2D) is a highly prevalent and chronic metabolic disorder. Recent evidence suggests that formation of toxic aggregates of the islet amyloid polypeptide (IAPP) might contribute to β-cell dysfunction and disease. However, the mechanism of protein aggregation and associated toxicity remains unclear. Misfolding, aggregation, and accumulation of diverse proteins in various organs is the hallmark of the group of protein misfolding disorders (PMDs), including highly prevalent illnesses affecting the central nervous system (CNS) such as Alzheimer's disease (AD) and Parkinson's disease (PD). In this review we discuss the current understanding of the mechanisms implicated in the formation of protein aggregates in the endocrine pancreas and associated toxicity in the light of the long-standing knowledge from neurodegenerative disorders associated with protein misfolding.
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Affiliation(s)
- Abhisek Mukherjee
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA
| | - Diego Morales-Scheihing
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA; Universidad de los Andes, Facultad de Medicina, Av. San Carlos de Apoquindo 2200, Las Condes, Santiago, Chile
| | - Peter C Butler
- Larry L. Hillblom Islet Research Center, University of California at Los Angeles, Los Angeles, CA, USA
| | - Claudio Soto
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA.
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89
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Del Monte F, Agnetti G. Protein post-translational modifications and misfolding: new concepts in heart failure. Proteomics Clin Appl 2015; 8:534-42. [PMID: 24946239 DOI: 10.1002/prca.201400037] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 05/20/2014] [Accepted: 06/11/2014] [Indexed: 11/09/2022]
Abstract
A new concept in the field of heart-failure (HF) research points to a role of misfolded proteins, forming preamyloid oligomers (PAOs), in cardiac toxicity. This is largely based on few studies reporting the presence of PAOs, similar to those observed in neurodegenerative diseases, in experimental and human HF. As the majority of proteinopathies are sporadic in nature, protein post-translational modifications (PTMs) likely play a major role in this growing class of diseases. In fact, PTMs are known regulators of protein folding and of the formation of amyloid species in well-established proteinopathies. Proteomics has been instrumental in identifying both chemical and enzymatic PTMs, with a potential impact on protein mis-/folding. Here we provide the basics on how proteins fold along with a few examples of PTMs known to modulate protein misfolding and aggregation, with particular focus on the heart. Due to its innovative content and the growing awareness of the toxicity of misfolded proteins, an "Alzheimer's theory of HF" is timely. Moreover, the continuous innovations in proteomic technologies will help pinpoint PTMs that could contribute to the process. This nuptial between biology and technology could greatly assist in identifying biomarkers with increased specificity as well as more effective therapies.
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Affiliation(s)
- Federica Del Monte
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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90
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El Assar M, Angulo J, Santos-Ruiz M, Moreno P, Novials A, Villanueva-Peñacarrillo ML, Rodríguez-Mañas L. Differential effect of amylin on endothelial-dependent vasodilation in mesenteric arteries from control and insulin resistant rats. PLoS One 2015; 10:e0120479. [PMID: 25807378 PMCID: PMC4373784 DOI: 10.1371/journal.pone.0120479] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 01/22/2015] [Indexed: 02/05/2023] Open
Abstract
Insulin resistance (IR) is frequently associated with endothelial dysfunction and has been proposed to play a major role in cardiovascular disease (CVD). On the other hand, amylin has long been related to IR. However the role of amylin in the vascular dysfunction associated to IR is not well addressed. Therefore, the aim of the study was to assess the effect of acute treatment with amylin on endothelium-dependent vasodilation of isolated mesenteric arteries from control (CR) and insulin resistant (IRR) rats and to evaluate the possible mechanisms involved. Five week-old male Wistar rats received 20% D-fructose dissolved in drinking water for 8 weeks and were compared with age-matched CR. Plasmatic levels of glucose, insulin and amylin were measured. Mesenteric microvessels were dissected and mounted in wire myographs to evaluate endothelium-dependent vasodilation to acetylcholine. IRR displayed a significant increase in plasmatic levels of glucose, insulin and amylin and reduced endothelium-dependent relaxation when compared to CR. Acute treatment of mesenteric arteries with r-amylin (40 pM) deteriorated endothelium-dependent responses in CR. Amylin-induced reduction of endothelial responses was unaffected by the H2O2 scavenger, catalase, but was prevented by the extracellular superoxide scavenger, superoxide dismutase (SOD) or the NADPH oxidase inhibitor (VAS2870). By opposite, amylin failed to further inhibit the impaired relaxation in mesenteric arteries of IRR. SOD, or VAS2870, but not catalase, ameliorated the impairment of endothelium-dependent relaxation in IRR. At concentrations present in insulin resistance conditions, amylin impairs endothelium-dependent vasodilation in mircrovessels from rats with preserved vascular function and low levels of endogenous amylin. In IRR with established endothelial dysfunction and elevated levels of amylin, additional exposure to this peptide has no effect on endothelial vasodilation. Increased superoxide generation through NADPH oxidase activity may be a common link involved in the endothelial dysfunction associated to insulin resistance and to amylin exposure in CR.
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Affiliation(s)
- Mariam El Assar
- Fundación para la Investigación Biomédica del Hospital Universitario de Getafe, Getafe, Madrid, Spain
| | - Javier Angulo
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Ramón y Cajal, Madrid, Spain
| | - Marta Santos-Ruiz
- Servicio de Análisis Clínicos del Hospital Universitario de Getafe, Getafe, Madrid, Spain
| | - Paola Moreno
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, Maryland, United States of America
| | - Anna Novials
- Diabetes and Obesity Research Laboratory, Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - María Luisa Villanueva-Peñacarrillo
- Department of Metabolism, Nutrition & Hormones, Instituto de Investigación Sanitaria (IIS)-Fundación Jiménez Díaz, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Leocadio Rodríguez-Mañas
- Fundación para la Investigación Biomédica del Hospital Universitario de Getafe, Getafe, Madrid, Spain
- Servicio de Geriatría del Hospital Universitario de Getafe, Getafe, Madrid, Spain
- * E-mail:
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Sidorova TN, Yermalitskaya LV, Mace LC, Wells KS, Boutaud O, Prinsen JK, Davies SS, Roberts LJ, Dikalov SI, Glabe CG, Amarnath V, Barnett JV, Murray KT. Reactive γ-ketoaldehydes promote protein misfolding and preamyloid oligomer formation in rapidly-activated atrial cells. J Mol Cell Cardiol 2015; 79:295-302. [PMID: 25463275 PMCID: PMC4302000 DOI: 10.1016/j.yjmcc.2014.11.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/24/2014] [Accepted: 11/12/2014] [Indexed: 01/15/2023]
Abstract
Rapid activation causes remodeling of atrial myocytes resembling that which occurs in experimental and human atrial fibrillation (AF). Using this cellular model, we previously observed transcriptional upregulation of proteins implicated in protein misfolding and amyloidosis. For organ-specific amyloidoses such as Alzheimer's disease, preamyloid oligomers (PAOs) are now recognized to be the primary cytotoxic species. In the setting of oxidative stress, highly-reactive lipid-derived mediators known as γ-ketoaldehydes (γ-KAs) have been identified that rapidly adduct proteins and cause PAO formation for amyloid β1-42 implicated in Alzheimer's. We hypothesized that rapid activation of atrial cells triggers oxidative stress with lipid peroxidation and formation of γ-KAs, which then rapidly crosslink proteins to generate PAOs. To investigate this hypothesis, rapidly-paced and control, spontaneously-beating atrial HL-1 cells were probed with a conformation-specific antibody recognizing PAOs. Rapid stimulation of atrial cells caused the generation of cytosolic PAOs along with a myocyte stress response (e.g., transcriptional upregulation of Nppa and Hspa1a), both of which were absent in control, unpaced cells. Rapid activation also caused the formation of superoxide and γ-KA adducts in atriomyocytes, while direct exposure of cells to γ-KAs resulted in PAO production. Increased cytosolic atrial natriuretic peptide (ANP), and the generation of ANP oligomers with exposure to γ-KAs and rapid atrial HL-1 cell stimulation, strongly suggest a role for ANP in PAO formation. Salicylamine (SA) is a small molecule scavenger of γ-KAs that can protect proteins from modification by these reactive compounds. PAO formation and transcriptional remodeling were inhibited when cells were stimulated in the presence of SA, but not with the antioxidant curcumin, which is incapable of scavenging γ-KAs. These results demonstrate that γ-KAs promote protein misfolding and PAO formation as a component of the atrial cell stress response to rapid activation, and they provide a potential mechanistic link between oxidative stress and atrial cell injury.
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Affiliation(s)
- Tatiana N Sidorova
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Liudmila V Yermalitskaya
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Lisa C Mace
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - K Sam Wells
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Olivier Boutaud
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Joseph K Prinsen
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Sean S Davies
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - L Jackson Roberts
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Sergey I Dikalov
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | | | - Venkataraman Amarnath
- Departments of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Joey V Barnett
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, 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. [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] [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] [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] [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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95
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Zhang S, Liu H, Chuang CL, Li X, Au M, Zhang L, Phillips ARJ, Scott DW, Cooper GJS. The pathogenic mechanism of diabetes varies with the degree of overexpression and oligomerization of human amylin in the pancreatic islet β cells. FASEB J 2014; 28:5083-96. [PMID: 25138158 DOI: 10.1096/fj.14-251744] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The aggregation of human amylin (hA) to form cytotoxic structures has been closely associated with the causation of type 2 diabetes. We sought to advance understanding of how altered expression and aggregation of hA might link β-cell degeneration with diabetes onset and progression, by comparing phenotypes between homozygous and hemizygous hA-transgenic mice. The homozygous mice displayed elevated islet hA that correlated positively with measures of oligomer formation (r=0.91; P<0.0001). They also developed hyperinsulinemia with transient insulin resistance during the prediabetes stage and then underwent rapid β-cell loss, culminating in severe juvenile-onset diabetes. The prediabetes stage was prolonged in the hemizygous mice, wherein β-cell dysfunction and extensive oligomer formation occurred in adulthood at a much later stage, when hA levels were lower (r=-0.60; P<0.0001). This is the first report to show that hA-evoked diabetes is associated with age, insulin resistance, progressive islet dysfunction, and β-cell apoptosis, which interact variably to cause the different diabetes syndromes. The various levels of hA elevation cause different extents of oligomer formation in the disease stages, thus eliciting early- or adult-onset diabetes syndromes, reminiscent of type 1 and 2 diabetes, respectively. Thus, the hA-evoked diabetes phenotypes differ substantively according to degree of amylin overproduction. These findings are relevant to the understanding of the pathogenesis and the development of experimental therapeutics for diabetes.
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Affiliation(s)
- Shaoping Zhang
- The School of Biological Sciences and The Maurice Wilkins Centre for Molecular BioDiscovery, Faculty of Science, University of Auckland, Auckland, New Zealand
| | - Hong Liu
- The School of Biological Sciences and
| | | | | | - Maggie Au
- The School of Biological Sciences and
| | - Lin Zhang
- The School of Biological Sciences and
| | - Anthony R J Phillips
- The School of Biological Sciences and The Maurice Wilkins Centre for Molecular BioDiscovery, Faculty of Science, University of Auckland, Auckland, New Zealand
| | | | - Garth J S Cooper
- The School of Biological Sciences and The Maurice Wilkins Centre for Molecular BioDiscovery, Faculty of Science, University of Auckland, Auckland, New Zealand Centre for Advanced Discovery and Experimental Therapeutics, Central Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester, UK; and Centre for Endocrinology and Diabetes, Institute of Human Development, Faculty of Medical and Human Sciences, Manchester Academic Health Sciences Centre, The University of Manchester, Manchester, UK
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96
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Berhanu WM, Hansmann UHE. Inter-species cross-seeding: stability and assembly of rat-human amylin aggregates. PLoS One 2014; 9:e97051. [PMID: 24810618 PMCID: PMC4014569 DOI: 10.1371/journal.pone.0097051] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 03/28/2014] [Indexed: 12/14/2022] Open
Abstract
Diseases such as type 2 diabetes, Alzheimer's and Parkinson's share as common feature the accumulation of mis-folded disease-specific protein aggregates into fibrillar structures, or plaques. These fibrils may either be toxic by themselves, or act as reservoirs for smaller cytotoxic oligomers. This suggests to investigate molecules as potential therapeutics that either reduce fibril formation or increase fibril stability. One example is rat amylin, which can inhibit aggregation of human amylin, a hallmark of type 2 diabetes. In the present paper, we use molecular dynamics to compare the stability of various preformed aggregates, built out of either human amylin, rat amylin, or mixtures of both. We considered two types of fibril-like oligomers: a single-layer in-register conformation, and a double-layer conformation in which the first U-shaped layer consists of rat amylin and the second layer of human amylin. Our results explain the weak amyloid-inhibiting properties of rat amylin and suggest that membrane leakage due to pore formation is responsible for the toxicity of rat amylin observed in a recent experiment. Together, our results put in question the use of rat amylin or the similar FDA approved drug pramlintide as an inhibitor of human amylin aggregation. They also point to mixed human-rat amylin fibril-like oligomers as possible model-systems for studies of amyloid formation that involve cross-species transmission.
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Affiliation(s)
- Workalemahu M. Berhanu
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Ulrich H. E. Hansmann
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, United States of America
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97
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Despa F, Decarli C. Amylin: what might be its role in Alzheimer's disease and how could this affect therapy? Expert Rev Proteomics 2014; 10:403-5. [PMID: 24117198 DOI: 10.1586/14789450.2013.841549] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Florin Despa
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 900 S Limestone, Lexington, KY 40536, USA
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98
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Beloukas AI, Magiorkinis E, Tsoumakas TL, Kosma AG, Diamantis A. Milestones in the History of Research on Cardiac Energy Metabolism. Can J Cardiol 2013; 29:1504-11. [DOI: 10.1016/j.cjca.2012.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 10/03/2012] [Accepted: 10/09/2012] [Indexed: 12/21/2022] Open
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99
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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: 455] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [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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Circulation Research
Thematic Synopsis Diabetes and Obesity. Circ Res 2013; 113:e62-75. [DOI: 10.1161/circresaha.113.302431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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