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Insulin AND amyloid

Vishal Kothari, Yuwen Luo, Talia Tornabene, Ann Marie O'Neill, Michael W Greene, Geetha Thangiah, Jeganathan Ramesh Babu
High fat diet-induced obesity is associated with insulin resistance (IR) and other chronic, diet related illnesses, including dementia. Alzheimer disease is the most common form of dementia, and is characterized by the presence of amyloid plaques and neurofibrillary tangles in brain. This study was designed to determine whether diet-induced changes in peripheral insulin sensitivity could contribute to alterations in brain insulin signaling and cognitive functions. Four week old, male C57BL/6NHsd mice were randomly assigned a high fat diet (40% energy from fat) with 42g/L liquid sugar (HFS) added to the drinking water or a normal chow diet (12% energy from fat) for 14weeks...
October 19, 2016: Biochimica et Biophysica Acta
Sanjay Kisan Metkar, Agnishwar Girigoswami, Ramachandran Murugesan, Koyeli Girigoswami
A transition of amyloidogenic protein by alternative folding pathway under certain conditions leads to the formation of protease resistant amyloid fibrils, having predominantly cross β structure. These amyloids are related to various neurodegenerative diseases and clearance of such amyloids may be a therapeutic approach for amyloid-related diseases. Insulin, that can form amyloids, is widely used as a model amyloidogenic protein for the study of various amyloid related diseases. In this study, insulin amyloids were formed in vitro and the potential of Serratiopeptidase (SP), a fibrinolytic-like serine protease, towards the dissociation of insulin amyloids was explored...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Shokei Kim-Mitsuyama
There is accumulating evidence that RAS inhibitors not only reduce blood pressure, but also exert pleiotropic effects, including a renoprotective effect, amelioration of insulin resistance, reduction in onset of diabetes, and suppression of cardiovascular remodelling,. However, the definite benefit of RAS inhibition in treatment of hypertension with CKD or DM is not conclusive. We previously performed the OlmeSartan and Calcium Antagonists Randomized (OSCAR) study comparing the preventive effect of high-dose ARB therapy versus ARB plus CCB combination therapy on cardiovascular morbidity and mortality in 1164 Japanese elderly hypertensive patients with baseline type 2 diabetes and/or CVD (Am J Med (2012))...
September 2016: Journal of Hypertension
Mamoru Haratake, Tohru Takiguchi, Naho Masuda, Sakura Yoshida, Takeshi Fuchigami, Morio Nakayama
Sup35 is a prion-like protein from yeast and shares the ability to transmit its aberrant fold and to aggregate into amyloid fibrils. (7)GNNQQNY(13) from the prion-determining domain of Sup35 was reported to form an amyloid. We first investigated the self-aggregation transition behavior of GNNQQNY to the β-sheet amyloid state under various conditions. Mechanical stirring using a magnetic bar resulted in accelerated aggregation of the GNNQQNY. The aggregation rate of GNNQQNY was also dependent on its concentration; the higher the GNNQQNY concentration, the faster the aggregation...
October 7, 2016: Colloids and Surfaces. B, Biointerfaces
N Rajasekar, Chandishwar Nath, Kashif Hanif, Rakesh Shukla
Alzheimer's disease (AD) is associated with reduced insulin level and impairment of insulin receptor (IR) signaling in the brain, which correlates to amyloid pathology, neuroinflammation, and synaptic neurotoxicity. Clinical studies show that intranasal insulin improves memory in AD patients without peripheral hypoglycemia. However, neuroprotective molecular mechanism of the beneficial effect of intranasal insulin in AD pathology is unexplored. Therefore, we investigated the role of intranasal insulin on intracerebroventricular (ICV) streptozotocin (STZ)-induced memory impairment in rats as evaluated in the Morris water maze test...
October 11, 2016: Molecular Neurobiology
E Candeias, A I Duarte, I Sebastião, M A Fernandes, A I Plácido, C Carvalho, S Correia, R X Santos, R Seiça, M S Santos, C R Oliveira, P I Moreira
Type 2 diabetes (T2D) is a highly concerning public health problem of the twenty-first century. Currently, it is estimated that T2D affects 422 million people worldwide with a rapidly increasing prevalence. During the past two decades, T2D has been widely shown to have a major impact in the brain. This, together with the cognitive decline and increased risk for dementia upon T2D, may arise from the complex interaction between normal brain aging and central insulin signaling dysfunction. Among the several features shared between T2D and some neurodegenerative disorders (e...
October 11, 2016: Molecular Neurobiology
O S Levin, E E Vasenina
Amyloid hypothesis of Alzheimer's disease (AD) has been long the primary one. During the 25-year history the concept has been dramatically changed. Accumulation of β-amyloid is associated not only with the disruption of its synthesis (as it seemed after the discovery of genetic mechanisms of some familial cases of AD) but rather with the disruption of its clearance and elimination from the brain tissue via the microcirculatory system. It has been recognized that soluble oligomers of β-amyloid, but not senile plaques that consisted of insoluble conjugates described by A...
2016: Zhurnal Nevrologii i Psikhiatrii Imeni S.S. Korsakova
Antonella Tramutola, Andrea Arena, Chiara Cini, D Allan Butterfield, Eugenio Barone
Clinical studies suggest a link between peripheral insulin resistance and cognitive dysfunction. Post-mortem analyses of Alzheimer disease (AD) subjects revealed insulin resistance in the brain, suggesting a role of this condition in cognitive deficits observed in AD. In this review, we focus on the glucagon-like peptide-1 (GLP-1) signaling pathway, whose role in the brain is collecting increasing attention because of its association with insulin signaling activation. Areas covered: The role of GLP-1-mediated effects in the brain and how they are affected along the progression of AD pathology is discussed...
October 7, 2016: Expert Review of Neurotherapeutics
Luiza C S Erthal, Adriana F Marques, Fábio C L Almeida, Gustavo L M Melo, Camila M Carvalho, Leonardo C Palmieri, Katia M S Cabral, Giselle N Fontes, Luís Maurício T R Lima
The secretory granule of the pancreatic β-cells is a zinc-rich environment copopulated with the hormones amylin and insulin. The human amylin is shown to interact with zinc ions with major contribution from the single histidine residue, which is absent in amylin from other species such as cat, rhesus and rodents. We report here the interaction of murine amylin with zinc ions in vitro. The self-assembly of murine amylin is tightly regulated by zinc and pH. Ion mobility mass spectrometry revealed zinc interaction with monomers and oligomers...
November 2016: Biophysical Chemistry
Andrés Norambuena, Horst Wallrabe, Lloyd McMahon, Antonia Silva, Eric Swanson, Shahzad S Khan, Daniel Baerthlein, Erin Kodis, Salvatore Oddo, James W Mandell, George S Bloom
A major obstacle to presymptomatic diagnosis and disease-modifying therapy for Alzheimer's disease (AD) is inadequate understanding of molecular mechanisms of AD pathogenesis. For example, impaired brain insulin signaling is an AD hallmark, but whether and how it might contribute to the synaptic dysfunction and neuron death that underlie memory and cognitive impairment has been mysterious. Neuron death in AD is often caused by cell cycle reentry (CCR) mediated by amyloid-β oligomers (AβOs) and tau, the precursors of plaques and tangles...
September 29, 2016: Alzheimer's & Dementia: the Journal of the Alzheimer's Association
Srivastav Ranganathan, Samir K Maji, Ranjith Padinhateeri
Self-assembly of proteins into ordered, fibrillar structures is a commonly observed theme in biology. It has been observed that diverse set of proteins (e.g alpha-synuclein, insulin, TATA-box binding protein, Sup35, p53), independent of their sequence, native structure, or function could self-assemble into highly ordered structures known as amyloids. What are the crucial features underlying amyloidogenesis that make it so generic? Using coarse-grained simulations of peptide self-assembly, we argue that variation in two physical parameters- bending-stiffness of the polypeptide and strength of inter-molecular interactions- can give rise to many of the structural features typically associated with amyloid self-assembly...
October 3, 2016: Journal of the American Chemical Society
Maryam Chinisaz, Azadeh Ebrahim-Habibi, Ahmad-Reza Dehpour, Parichehreh Yaghmaei, Kazem Parivar, Ali Akbar Moosavi-Movahedi
Insulin is a therapeutic protein whose amyloid formation is reported in diabetic patients. Four anhydride compounds were used in the current study in order to experiment their potential reducing effect on insulin propensity to form amyloid fibrils. The modified forms (obtained with succinic-, 3,3-dimethylglutaric, 2-phenylglutaric-, and (2-Dodecen-1-yl) succinic anhydride), were first characterized with regard to melting temperature (Tm), changes in secondary structure percentage and hydrophobic surface. Fibril formation was then assessed by Congo red absorbance kinetics and transmission electron microscopy...
September 27, 2016: European Journal of Pharmaceutical Sciences
Bhisma N Ratha, Anirban Ghosh, Jeffrey R Brender, Nilanjan Gayen, Humaira Ilyas, Chilukoti Neeraja, Kali P Das, Atin K Mandal, Anirban Bhunia
The aggregation of insulin into amyloid fibers has been a limiting factor in the development of fast acting insulin analogues, creating a demand for excipients that limit aggregation. Despite the potential demand, inhibitors targeted specifically at insulin have been few in number. Here we report a designed, non-toxic and serum stable heptapeptide, KR7 (KPWWPRR) that differs significantly from the primarily hydrophobic sequences that have been previously used to interfere with the insulin amyloid fibrillation...
September 27, 2016: Journal of Biological Chemistry
Dayana Cabral da Silva, Giselle N Fontes, Luiza C S Erthal, Luís Maurício T R Lima
Amylin is a pancreatic peptide hormone co-secreted along with insulin by the β-cells. It is found in amyloid deposits in both type 2 diabetic individuals and elder non-diabetic. The triple proline amylinomimetic compound (25,28,29-Pro-human amylin) named pramlintide was designed aiming to solve the solubility and amyloid characteristics of human amylin. We have found by using ion mobility spectrometry-based mass spectrometry that pramlintide is able to assembly into multimers. Pramlintide formed amyloid fibrils in vitro in a pH-dependent kinetic process within a few hours, as followed by thioflavin T, quantification of soluble peptide and further characterized by transmission electron microscopy, atomic force microscopy and X-ray diffraction...
September 20, 2016: Biophysical Chemistry
Tanja Deckert-Gaudig, Dmitry Kurouski, Martin A B Hedegaard, Pushkar Singh, Igor K Lednev, Volker Deckert
The formation of insoluble β-sheet-rich protein structures known as amyloid fibrils is associated with numerous neurodegenerative diseases, such as Alzheimer's and Parkinson's disease. A detailed understanding of the molecular structure of the fibril surface is of interest as the first contact with the physiological environment in vivo and plays a decisive role in biological activity and associated toxicity. Recent studies reveal that the inherent sensitivity and specificity of tip-enhanced Raman scattering (TERS) renders this technique a compelling method for fibril surface analysis at the single-particle level...
2016: Scientific Reports
Shokei Kim-Mitsuyama
There is accumulating evidence that RAS inhibitors not only reduce blood pressure, but also exert pleiotropic effects, including a renoprotective effect, amelioration of insulin resistance, reduction in onset of diabetes, and suppression of cardiovascular remodelling,. However, the definite benefit of RAS inhibition in treatment of hypertension with CKD or DM is not conclusive. We previously performed the OlmeSartan and Calcium Antagonists Randomized (OSCAR) study comparing the preventive effect of high-dose ARB therapy versus ARB plus CCB combination therapy on cardiovascular morbidity and mortality in 1164 Japanese elderly hypertensive patients with baseline type 2 diabetes and/or CVD (Am J Med (2012))...
September 2016: Journal of Hypertension
Niyati H Mudliar, Biswajit Sadhu, Aafrin M Pettiwala, Prabhat K Singh
Recently, Auramine O (AuO) has been projected as a fluorescent fibril sensor, and it has been claimed that AuO has an advantage over the most extensively utilized fibril marker, Thioflavin-T (ThT), owing to the presence of an additional large red-shifted emission band for AuO, which was observed exclusively for AuO in the presence of fibrillar media and not in protein or buffer media. As fibrils are very rich in β-sheet structure, a fibril sensor should be more specific toward the β-sheet structure so as to produce a large contrast between the fibril form and native protein form, for efficient detection and in vitro mechanistic studies of fibrillation...
October 13, 2016: Journal of Physical Chemistry. B
Silke Herzer, Sascha Meldner, Klara Rehder, Hermann-Josef Gröne, Viola Nordström
Decreased neuronal insulin receptor (IR) signaling in Alzheimer's disease is suggested to contribute to synaptic loss and neurodegeneration. This work shows that alteration of membrane microdomains increases IR levels and signaling, as well as neuronal viability in AD models in vitro and in vivo. Neuronal membrane microdomains are highly enriched in gangliosides. We found that inhibition of glucosylceramide synthase (GCS), the key enzyme of ganglioside biosynthesis, increases viability of cortical neurons in 5xFAD mice, as well as in cultured neurons exposed to oligomeric amyloid-β-derived diffusible ligands (ADDLs)...
2016: Acta Neuropathologica Communications
A Zaccone, I Terentjev, T W Herling, T P J Knowles, A Aleksandrova, E M Terentjev
While a significant body of investigations have been focused on the process of protein self-assembly, much less is understood about the reverse process of a filament breaking due to thermal motion into smaller fragments, or depolymerization of subunits from the filament ends. Indirect evidence for actin and amyloid filament fragmentation has been reported, although the phenomenon has never been directly observed either experimentally or in simulations. Here we report the direct observation of filament depolymerization and breakup in a minimal, calibrated model of coarse-grained molecular simulation...
September 14, 2016: Journal of Chemical Physics
Rodolfo Guardado-Mendoza, Alberto O Chávez, Lilia M Jiménez-Ceja, Andrea Hansis-Diarte, Ralph A DeFronzo, Franco Folli, Devjit Tripathy
AIMS: Pancreatic islet amyloid deposition is a characteristic feature of type 2 diabetes mellitus (T2DM). Islet amyloid polypeptide (IAPP) is co-secreted with insulin, but its secretion profile and relationship to insulin and C-peptide in response to glucose and non-glucose stimuli has not been clearly defined. METHODS: Forty subjects (13 NGT, 12 IGT and 15 T2DM) participated in an OGTT and two-step hyperglycemic (225 and 400 mg/dl) clamp (80 min/step) followed by an IV arginine bolus...
September 13, 2016: Acta Diabetologica
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