Publications by authors named "Philip Newsholme"

133 Publications

Deficiency Does Not Directly Impair the Innate Immune Response in a Murine Model of Generalized Lipodystrophy.

J Clin Med 2021 Jan 23;10(3). Epub 2021 Jan 23.

The Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.

Congenital Generalized Lipodystrophy type 2 (CGL2) is the most severe form of lipodystrophy and is caused by mutations in the gene. Affected patients exhibit a near complete lack of adipose tissue and suffer severe metabolic disease. A recent study identified infection as a major cause of death in CGL2 patients, leading us to examine whether loss could directly affect the innate immune response. We generated a novel mouse model selectively lacking in the myeloid lineage (LysM-B2KO) and also examined the function of bone-marrow-derived macrophages (BMDM) isolated from global knockout (SKO) mice. LysM-B2KO mice failed to develop lipodystrophy and metabolic disease, providing a model to study the direct role of in myeloid lineage cells. Lipopolysaccharide-mediated stimulation of inflammatory cytokines was not impaired in LysM-B2KO mice or in BMDM isolated from either LysM-B2KO or SKO mice. Additionally, intracellular fate and clearance of bacteria in SKO BMDM challenged with was indistinguishable from that in BMDM isolated from littermate controls. Overall, our findings reveal that selective deficiency in macrophages does not critically impact the innate immune response to infection. Instead, an increased susceptibility to infection in CGL2 patients is likely to result from severe metabolic disease.
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http://dx.doi.org/10.3390/jcm10030441DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7865406PMC
January 2021

Host cell glutamine metabolism as a potential antiviral target.

Clin Sci (Lond) 2021 01;135(2):305-325

Interdisciplinary Program of Health Sciences, Cruzeiro do Sul University, GalvãoBueno, 868, Liberdade, 01506-000, SãoPaulo, São Paulo, Brazil.

A virus minimally contains a nucleic acid genome packaged by a protein coat. The genome and capsid together are known as the nucleocapsid, which has an envelope containing a lipid bilayer (mainly phospholipids) originating from host cell membranes. The viral envelope has transmembrane proteins that are usually glycoproteins. The proteins in the envelope bind to host cell receptors, promoting membrane fusion and viral entry into the cell. Virus-infected host cells exhibit marked increases in glutamine utilization and metabolism. Glutamine metabolism generates ATP and precursors for the synthesis of macromolecules to assemble progeny viruses. Some compounds derived from glutamine are used in the synthesis of purines and pyrimidines. These latter compounds are precursors for the synthesis of nucleotides. Inhibitors of glutamine transport and metabolism are potential candidate antiviral drugs. Glutamine is also an essential nutrient for the functions of leukocytes (lymphocyte, macrophage, and neutrophil), including those in virus-infected patients. The increased glutamine requirement for immune cell functions occurs concomitantly with the high glutamine utilization by host cells in virus-infected patients. The development of antiviral drugs that target glutamine metabolism must then be specifically directed at virus-infected host cells to avoid negative effects on immune functions. Therefore, the aim of this review was to describe the landscape of cellular glutamine metabolism to search for potential candidates to inhibit glutamine transport or glutamine metabolism.
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http://dx.doi.org/10.1042/CS20201042DOI Listing
January 2021

Are Heat Shock Proteins an Important Link between Type 2 Diabetes and Alzheimer Disease?

Int J Mol Sci 2020 Nov 2;21(21). Epub 2020 Nov 2.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Biosciences, Curtin University, Perth 6102, Australia.

Type 2 diabetes (T2D) and Alzheimer's disease (AD) are growing in prevalence worldwide. The development of T2D increases the risk of AD disease, while AD patients can show glucose imbalance due to an increased insulin resistance. T2D and AD share similar pathological features and underlying mechanisms, including the deposition of amyloidogenic peptides in pancreatic islets (i.e., islet amyloid polypeptide; IAPP) and brain (β-Amyloid; Aβ). Both IAPP and Aβ can undergo misfolding and aggregation and accumulate in the extracellular space of their respective tissues of origin. As a main response to protein misfolding, there is evidence of the role of heat shock proteins (HSPs) in moderating T2D and AD. HSPs play a pivotal role in cell homeostasis by providing cytoprotection during acute and chronic metabolic stresses. In T2D and AD, intracellular HSP (iHSP) levels are reduced, potentially due to the ability of the cell to export HSPs to the extracellular space (eHSP). The increase in eHSPs can contribute to oxidative damage and is associated with various pro-inflammatory pathways in T2D and AD. Here, we review the role of HSP in moderating T2D and AD, as well as propose that these chaperone proteins are an important link in the relationship between T2D and AD.
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http://dx.doi.org/10.3390/ijms21218204DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662599PMC
November 2020

Vitamin D Supplementation Does Not Impact Resting Metabolic Rate, Body Composition and Strength in Vitamin D Sufficient Physically Active Adults.

Nutrients 2020 Oct 12;12(10). Epub 2020 Oct 12.

School of Physiotherapy and Exercise Science, Curtin University, Perth, WA 6102, Australia.

Supplementation with the most efficient form of Vitamin D (VitD3) results in improvements in energy metabolism, muscle mass and strength in VitD deficient individuals. Whether similar outcomes occur in VitD sufficient individuals' remains to be elucidated. The aim of this study is to determine the effect of VitD3 supplementation on resting metabolic rate (RMR), body composition and strength in VitD sufficient physically active young adults. Participants completed pre-supplementation testing before being matched for sunlight exposure and randomly allocated in a counterbalanced manner to the VitD3 or placebo group. Following 12 weeks of 50 IU/kg body-mass VitD3 supplementation, participants repeated the pre-supplementation testing. Thirty-one adults completed the study (19 females and 12 males; mean ± standard deviation (SD); age = 26.6 ± 4.9 years; BMI = 24.2 ± 4.1 kg·m). The VitD group increased serum total 25(OH)D by 30 nmol/L while the placebo group decreased total serum concentration by 21 nmol/L, reaching 123 (51) and 53 (42.2) nmol/L, respectively. There were no significant changes in muscle strength or power, resting metabolic rate and body composition over the 12-week period. Physically active young adults that are VitD sufficient have demonstrated that no additional physiological effects of achieving supraphysiological serum total 25(OH)D concentrations after VitD3 supplementation.
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http://dx.doi.org/10.3390/nu12103111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7601703PMC
October 2020

Serum Vitamin D status is associated with increased blastocyst development rate in women undergoing IVF.

Reprod Biomed Online 2020 Dec 21;41(6):1101-1111. Epub 2020 Aug 21.

School of Pharmacy and Biomedical Sciences, Faculty of Health Sciences, Curtin University, Bentley WA 6845, Australia; PIVET Medical Centre, Leederville, Perth WA 6007, Australia. Electronic address:

Research Question: To determine the relationship between vitamin D (VitD) status and embryological, clinical pregnancy and live birth outcomes in women undergoing IVF.

Design: Cross-sectional, observational study conducted at a university-affiliated private IVF clinic. A total of 287 women underwent 287 IVF cycles and received a fresh embryo transfer. Patients had their serum 25-hydroxyvitamin D2/D3 (VitD) determined on the day of oocyte retrieval, which was analysed in relation to blastocyst development rate, clinical pregnancy and live birth outcomes.

Results: In stepwise, multivariable logistic regression models, increases in blastocyst development rate, number and quality, along with embryo cryopreservation and utilization rates were associated with women with a sufficient VitD status (≥20 ng/ml). For a single increase in the number of blastocysts generated per cycle or embryos cryopreserved per cycle, the likelihood for the patient to be VitD sufficient was increased by 32% (odds ratio [OR] 1.32, 95% confidence interval [CI] 1.10-1.58, P = 0.002 and OR 1.33, 95% CI 1.10-1.60, P = 0.004, respectively). Clinical pregnancy (40.7% versus 30.8%, P = 0.086) and live birth rates (32.9% versus 25.8%, P = 0.195) in the sufficient VitD group versus the insufficient group were not significantly different and VitD sufficiency was not significantly associated with these outcomes.

Conclusion: A strong relationship was observed between blastocyst development and VitD sufficiency. However, there was no association between VitD and clinical pregnancy or live birth outcomes. Further larger studies are needed to investigate whether the observed effect on blastocyst development may have downstream implications on subsequent clinical pregnancy or live birth rates, and on a potential mechanism where sufficient VitD concentrations are linked to improved IVF outcomes.
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http://dx.doi.org/10.1016/j.rbmo.2020.08.014DOI Listing
December 2020

Butyrate generated by gut microbiota and its therapeutic role in metabolic syndrome.

Pharmacol Res 2020 10 27;160:105174. Epub 2020 Aug 27.

School of Pharmacy and Biomedical Sciences, and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia. Electronic address:

Metabolic syndrome (MetS) and the associated incidence of cardiovascular disease and type 2 diabetes represents a significant contributor to morbidity and mortality worldwide. Butyrate, a short-chain fatty acid produced by the gut microbiome, has long been known to promote growth in farmed animals and more recently has been reported to improve body weight and composition, lipid profile, insulin sensitivity and glycaemia in animal models of MetS. In vitro studies have examined the influence of butyrate on intestinal cells, adipose tissue, skeletal muscle, hepatocytes, pancreatic islets and blood vessels, highlighting genes and pathways that may contribute to its beneficial effects. Butyrate's influences in these cells have been attributed primarily to its epigenetic effects as a histone deacetylase inhibitor, as well as its role as an agonist of free fatty acid receptors, but clear mechanistic evidence is lacking. There is also uncertainty whether results from animal studies can translate to human trials due to butyrate's poor systemic availability and rapid clearance. Hitherto, several small-scale human clinical trials have failed to show significant benefits in MetS patients. Further trials are clearly needed, including with formulations designed to improve butyrate's availability. Regardless, dietary intervention to increase the rate of butyrate production may be a beneficial addition to current treatment. This review outlines the current body of evidence on the suitability of butyrate supplementation for MetS, looking at mechanistic effects on the various components of MetS and highlighting gaps in the knowledge and roadblocks to its use in humans.
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http://dx.doi.org/10.1016/j.phrs.2020.105174DOI Listing
October 2020

The Critical Role of Cell Metabolism for Essential Neutrophil Functions.

Cell Physiol Biochem 2020 Jun;54(4):629-647

Interdisciplinary Post-graduate Program in Health Sciences, Cruzeiro of Sul University, Sao Paulo, Sao Paulo, Brazil.

Neutrophils were traditionally considered as short-lived cells with abundant secretory and protein synthetic activity. Recent studies, however, indicate neutrophils are in reality a heterogeneous population of cells. Neutrophils differentiate from pluripotent stem cells in the bone marrow, and can further mature in the blood stream and can have different phenotypes in health and disease conditions. Neutrophils undergo primary functions such as phagocytosis, production of reactive oxygen species (ROS), release of lipid mediators and inflammatory proteins (mainly cytokines), and apoptosis. Neutrophils stimulate other neutrophils and trigger a cascade of immune and inflammatory responses. The underpinning intracellular metabolisms that support these neutrophil functions are herein reported. It has been known for many decades that neutrophils utilize glucose as a primary fuel and produce lactate as an end product of glycolysis. Neutrophils metabolize glucose through glycolysis and the pentose- phosphate pathway (PPP). Mitochondrial glucose oxidation is very low. The PPP provides the reduced nicotinamide adenine dinucleotide phosphate (NADPH) for the NADPH-oxidase (NOX) complex activity to produce superoxide from oxygen. These cells also utilize glutamine and fatty acids to produce the required adenosine triphosphate (ATP) and precursors for the synthesis of molecules that trigger functional outcomes. Neutrophils obtained from rat intraperitoneal cavity and incubate for 1 hour at 37°C metabolize glutamine at higher rate than that of glucose. Glutamine delays neutrophil apoptosis and maintains optimal NOX activity for superoxide production. Under limited glucose provision, neutrophils move to fatty acid oxidation (FAO) to obtain the required energy for the cell function. FAO is mainly associated with neutrophil differentiation and maturation. Hypoxia, hormonal dysfunction, and physical exercise markedly change neutrophil metabolism. It is now become clear that neutrophil metabolism underlies the heterogeneity of neutrophil phenotypes and should be intense focus of investigation.
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http://dx.doi.org/10.33594/000000245DOI Listing
June 2020

Amylin and beta amyloid proteins interact to form amorphous heterocomplexes with enhanced toxicity in neuronal cells.

Sci Rep 2020 06 25;10(1):10356. Epub 2020 Jun 25.

School of Pharmacy and Biomedical Sciences, Curtin Health and Innovation Research Institute (CHIRI), Faculty of Health Sciences, Curtin University, Bentley, WA, 6107, Australia.

Human pancreatic islet amyloid polypeptide (hIAPP) and beta amyloid (Aβ) can accumulate in Type 2 diabetes (T2D) and Alzheimer's disease (AD) brains and evidence suggests that interaction between the two amyloidogenic proteins can lead to the formation of heterocomplex aggregates. However, the structure and consequences of the formation of these complexes remains to be determined. The main objective of this study was to characterise the different types and morphology of Aβ-hIAPP heterocomplexes and determine if formation of such complexes exacerbate neurotoxicity. We demonstrate that hIAPP promotes Aβ oligomerization and formation of small oligomer and large aggregate heterocomplexes. Co-oligomerized Aβ42-hIAPP mixtures displayed distinct amorphous structures and a 3-fold increase in neuronal cell death as compared to Aβ and hIAPP alone. However, in contrast to hIAPP, non-amyloidogenic rat amylin (rIAPP) reduced oligomer Aβ-mediated neuronal cell death. rIAPP exhibited reductions in Aβ induced neuronal cell death that was independent of its ability to interact with Aβ and form heterocomplexes; suggesting mediation by other pathways. Our findings reveal distinct effects of IAPP peptides in modulating Aβ aggregation and toxicity and provide new insight into the potential pathogenic effects of Aβ-IAPP hetero-oligomerization and development of IAPP based therapies for AD and T2D.
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http://dx.doi.org/10.1038/s41598-020-66602-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7316712PMC
June 2020

Angiotensin-Converting Enzyme Related-Polymorphisms on Inflammation, Muscle and Myocardial Damage After a Marathon Race.

Front Genet 2019 25;10:984. Epub 2019 Oct 25.

Institute of Physical Activity and Sports Sciences, Cruzeiro do Sul University, Sao Paulo, Brazil.

Muscle damage is one of the most important factors that affect muscle fatigue during endurance exercise. Recent evidence suggests that the renin-angiotensin system impacts on skeletal muscle wasting. The aim of this study was to determine association between the Met235Thr, I/D and -9/+9 polymorphisms with inflammation, myocardial and muscle injury induced by endurance exercise. Eighty-one Brazilian male runners participated in this study and completed the International Marathon of Sao Paulo. Muscle and myocardial damage markers (alanine transaminase, ALT, aspartate transaminase, AST, lactic dehydrogenase, LDH, creatine kinase, CK, Troponin, pro BNP, myoglobin, and CK-MB) and inflammatory mediators (IL-6, IL-8, IL-10, IL12p70, IL1β, and TNF-α) were determined one day before, immediately after, one day after, and three days after the event. Muscle damage was also determined fifteen days after race and angiotensinogen () Met235Thr, angiotensin-converting enzyme () I/D, and Bradykinin B2 receptor () -9/+9 polymorphisms were determined. Marathon race participation induced an increase in all muscle damage and inflammatory markers evaluated (p < 0.0001). The muscle damage markers, troponin and pro BNP, CK and LDH and inflammatory markers, IL-6, IL-8, IL-1β and IL-10 were also higher in II genotype immediately after race, compared to DD genotype. The percentage of runners higher responders (>500U/I) to CK levels was higher for II genotypes (69%) compared to DD and ID genotypes (38% and 40%, respectively) immediately after. Troponin, pro BNP and IL-1β, IL-8 levels were also elevated in MM genotype compared to TT genotype athletes after and/or one day after race. -9/-9 had pronounced response to LDH, CK, CK-MB and ALT and AST activities, myoglobin, troponin, IL-6, IL-8 levels immediately, one day and/or three days after race. The percentage of runners higher responders (>500U/I) to CK levels was greater for -9-9 and -9+9 genotypes (46 and 48%, respectively) compared to +9+9 genotypes (31%) immediately after. II, MM, and -9-9 genotypes may increase the susceptibility to inflammation, muscle injury after endurance exercise and could be used to predict the development of clinical conditions associated with muscle damage and myocardial injury.
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http://dx.doi.org/10.3389/fgene.2019.00984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823274PMC
October 2019

Nitric Oxide and Redox State Measurements in Pancreatic Beta Cells.

Methods Mol Biol 2020 ;2076:241-253

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia.

The role of oxidative stress in the pathogenesis of type 2 diabetes (T2D), especially pancreatic β-cell dysfunction and death, has become apparent in the last two decades. Peroxidase- and catalase-based antioxidant mechanisms are particularly weak in β-cells and can be easily overwhelmed by excessive production of reactive oxygen and nitrogen species in the course of pathological processes. Recent research has attempted to define in detail the mechanistic aspects of oxidative stress-induced β-cell dysfunction. Here, we describe the procedures for the measurement of various parameters important to assess oxidative stress in pancreatic β-cells. Detailed protocols for determination of nitric oxide (NO) production, the glutathione redox status, and general oxidative status in β-cells are presented in this chapter.
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http://dx.doi.org/10.1007/978-1-4939-9882-1_14DOI Listing
December 2020

Effects of vitamin D on primary human skeletal muscle cell proliferation, differentiation, protein synthesis and bioenergetics.

J Steroid Biochem Mol Biol 2019 10 3;193:105423. Epub 2019 Jul 3.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, 6102, Australia. Electronic address:

The active form of Vitamin D (1,25(OH)2D), has been suggested to have a regulatory role in skeletal muscle function and metabolism, however, the effects and mechanisms of vitamin D (VitD) action in this tissue remain to be fully established. In this study, we have used primary human skeletal muscle myoblast (HSMM) cells that display typical characteristics of human skeletal muscle function and protein levels, to investigate the effects of the active form of VitD on proliferation, differentiation, protein synthesis and bioenergetics. Myoblast cells were treated with 100 nM of VitD for 24 h, 48 h, 72 h and five days (cells were differentiated into myotubes) and then analyses were performed. We report that VitD inhibits myoblast proliferation and enhances differentiation by altering the expression of myogenic regulatory factors. In addition, we found that protein synthesis signaling improved in myotubes after VitD treatment in the presence of insulin. We also report an increase in oxygen consumption rate after 24 h of treatment in myoblasts and after 5 days of treatment in myotubes after VitD exposure. VitD significantly impacted HSMM myogenesis, as well as protein synthesis in the presence of insulin.
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http://dx.doi.org/10.1016/j.jsbmb.2019.105423DOI Listing
October 2019

Oxidative stress pathways in pancreatic β-cells and insulin-sensitive cells and tissues: importance to cell metabolism, function, and dysfunction.

Am J Physiol Cell Physiol 2019 09 19;317(3):C420-C433. Epub 2019 Jun 19.

Faculty of Health, Torrens University Australia, Melbourne, Victoria, Australia.

It is now accepted that nutrient abundance in the blood, especially glucose, leads to the generation of reactive oxygen species (ROS), ultimately leading to increased oxidative stress in a variety of tissues. In the absence of an appropriate compensatory response from antioxidant mechanisms, the cell, or indeed the tissue, becomes overwhelmed by oxidative stress, leading to the activation of intracellular stress-associated pathways. Activation of the same or similar pathways also appears to play a role in mediating insulin resistance, impaired insulin secretion, and late diabetic complications. The ability of antioxidants to protect against the oxidative stress induced by hyperglycemia and elevated free fatty acid (FFA) levels in vitro suggests a causative role of oxidative stress in mediating the latter clinical conditions. In this review, we describe common biochemical processes associated with oxidative stress driven by hyperglycemia and/or elevated FFA and the resulting clinical outcomes: β-cell dysfunction and peripheral tissue insulin resistance.
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http://dx.doi.org/10.1152/ajpcell.00141.2019DOI Listing
September 2019

Mechanisms of vitamin D action in skeletal muscle.

Nutr Res Rev 2019 12 17;32(2):192-204. Epub 2019 Jun 17.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia.

Vitamin D receptor expression and associated function have been reported in various muscle models, including C2C12, L6 cell lines and primary human skeletal muscle cells. It is believed that 1,25-hydroxyvitamin D3 (1,25(OH)2D3), the active form of vitamin D, has a direct regulatory role in skeletal muscle function, where it participates in myogenesis, cell proliferation, differentiation, regulation of protein synthesis and mitochondrial metabolism through activation of various cellular signalling cascades, including the mitogen-activated protein kinase pathway(s). It has also been suggested that 1,25(OH)2D3 and its associated receptor have genomic targets, resulting in regulation of gene expression, as well as non-genomic functions that can alter cellular behaviour through binding and modification of targets not directly associated with transcriptional regulation. The molecular mechanisms of vitamin D signalling, however, have not been fully clarified. Vitamin D inadequacy or deficiency is associated with muscle fibre atrophy, increased risk of chronic musculoskeletal pain, sarcopenia and associated falls, and may also decrease RMR. The main purpose of the present review is to describe the molecular role of vitamin D in skeletal muscle tissue function and metabolism, specifically in relation to proliferation, differentiation and protein synthesis processes. In addition, the present review also includes discussion of possible genomic and non-genomic pathways of vitamin D action.
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http://dx.doi.org/10.1017/S0954422419000064DOI Listing
December 2019

Glutamine deprivation induces metabolic adaptations associated with beta cell dysfunction and exacerbate lipotoxicity.

Mol Cell Endocrinol 2019 07 21;491:110433. Epub 2019 Apr 21.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, Western Australia, 6845, Australia. Electronic address:

Studies have reported that plasma glutamine is reduced in type 2 diabetes (T2D) patients. Glutamine supplementation improves glycaemic control, however the mechanisms are unclear. Here, we evaluated in vitro the pancreatic beta cell bioenergetic and insulin secretory responses to various levels of glutamine availability, or treatment in the presence of an inhibitor of intracellular glutamine metabolism. The impact of glutamine deprivation to the pathological events induced by the saturated fatty acid palmitate was also investigated. Glutamine deprivation induced a reduction in mitochondrial respiration and increase in glucose uptake and utilization. This phenotype was accompanied by impairment in beta cell function, as demonstrated by diminished insulin production and secretion, and activation of the unfolded protein response pathway. Palmitate led to insulin secretory dysfunction, loss of viability and apoptosis. Importantly, glutamine deprivation significantly exacerbated these phenotypes, suggesting that low glutamine levels could participate in the process of beta cell dysfunction in T2D.
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http://dx.doi.org/10.1016/j.mce.2019.04.013DOI Listing
July 2019

Statins Do Not Directly Inhibit the Activity of Major Epigenetic Modifying Enzymes.

Cancers (Basel) 2019 Apr 10;11(4). Epub 2019 Apr 10.

School of Pharmacy and Biomedical Sciences, and Curtin Health Innovation Research Institute, Curtin University, Bentley, WA 6102, Australia.

The potential anticancer effects of statins-a widely used class of cholesterol lowering drugs-has generated significant interest, as has the use of epigenetic modifying drugs such as HDAC and DNMT inhibitors. We set out to investigate the effect of statin drugs on epigenetic modifications in multiple cell lines, including hepatocellular carcinoma, breast carcinoma, leukemic macrophages, cervical adenocarcinoma, and insulin-secreting cells, as well as liver extracts from statin-treated C57B1/6J mice. Cells or cell extracts were treated with statins and with established epigenetic modulators, and HDAC, HAT, and DNMT activities were quantified. We also examined histone acetylation by immunoblotting. Statins altered neither HDAC nor HAT activity. Accordingly, acetylation of histones H3 and H4 was unchanged with statin treatment. However, statins tended to increase DNMT activity. These results indicate that direct inhibition of the major classes of epigenetic modifying enzymes, as previously reported elsewhere, is unlikely to contribute to any anticancer effects of statins. This study concerned global effects on epigenetic enzyme activities and histone acetylation; whether statins influence epigenetic modifications in certain genomic regions, cannot be ruled out and remains to be investigated.
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http://dx.doi.org/10.3390/cancers11040516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6521159PMC
April 2019

Use of virus-like particles as a native membrane model to study the interaction of insulin with the insulin receptor.

Biochim Biophys Acta Biomembr 2019 06 2;1861(6):1204-1212. Epub 2019 Apr 2.

School of Pharmacy and Biomedical Sciences, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley campus, Perth, Western Australia 6102, Australia. Electronic address:

There is emerging evidence of the utility of virus-like particles (VLPs) as a novel model for the study of receptor-ligand interactions in a native plasma membrane environment. VLPs consist of a viral core protein encapsulated by portions of the cell membrane with membrane proteins and receptors expressed in their native conformation. VLPs can be generated in mammalian cells by transfection with the retroviral core protein (gag). In this study, we used Chinese hamster ovary (CHO T10) cells stably overexpressing the insulin receptor (IR) to generate IR bearing VLPs. The diameter and size uniformity of VLPs were estimated by dynamic light scattering and morphological features examined by scanning electron microscopy. The presence of high affinity IR on VLPs was demonstrated by competitive binding assays (K: 2.3 ± 0.4 nM, n = 3), which was similar to that on the parental CHO T10 cells (K: 2.1 ± 0.4 nM, n = 3). We also report that increases or decreases in membrane cholesterol content by treatment with methyl-β-cyclodextrin (MBCD) or cholesterol pre-loaded methyl-β-cyclodextrin (cMBCD), respectively, substantially decreased insulin binding (> 30%) to both VLPs and cells, and we speculate this is due to a change in receptor disposition. We suggest that this novel finding of decreases in insulin binding in response to changes in membrane cholesterol content may largely account for the unexplained decreases in insulin signalling events previously reported elsewhere. Finally, we propose VLPs as a viable membrane model for the study of insulin-IR interactions in a native membrane environment.
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http://dx.doi.org/10.1016/j.bbamem.2019.03.021DOI Listing
June 2019

Epigenetic demethylation of sFRPs, with emphasis on sFRP4 activation, leading to Wnt signalling suppression and histone modifications in breast, prostate, and ovary cancer stem cells.

Int J Biochem Cell Biol 2019 04 30;109:23-32. Epub 2019 Jan 30.

Stem Cell and Cancer Biology Laboratory, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia. Electronic address:

The expression and levels of secreted frizzled-related proteins (sFRPs), important Wnt signalling antagonists, have been reported to be reduced in various cancers, and are associated with disease progression and poor prognosis. During tumour development, all sFRP (1, 2, 3, 4, and 5) genes are hypermethylated, causing transcriptional silencing. sFRPs have an ability to sensitize tumour cells to chemotherapeutic drugs, enhancing cell death. Reduced Wnt signalling is associated with loss of cancer stem cell (CSC) viability. We investigated the possible involvement of methylation-mediated silencing of the sFRP gene family in CSCs derived from breast, prostate, and ovarian tumour cell lines. Real-time RT-PCR studies indicated that loss or downregulation of sFRP (1-5) expression in tumours is associated with promoter hypermethylation. Additionally, CSCs derived from all tumour cell lines with sFRP (1-5) promotor hypermethylation expressed sFRP (1-5) mRNA after treatment with 5-Azacytidine (5-Aza), especially sFRP4, implying that DNA methylation is the predominant epigenetic mechanism for sFRP (1-5) silencing. Furthermore, post-translational modification (PTM) in total and histone proteins was observed post 5-Aza and sFRP4 treatment. Protein levels of Wnt downstream signalling components (GSK3β, active β-catenin, and phospho β-catenin) and epigenetic factors of histones (acetyl histone H3, and H3K27me3) affecting PTM were analysed. Our findings suggest that downregulation of sFRP4 expression in endocrine-related cancers can be attributed to aberrant promoter hypermethylation in conjugation with histone modification, and indicate the important role of methylation-induced gene silencing of sFRP4 in survival and proliferation of CSCs derived from these cancers.
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http://dx.doi.org/10.1016/j.biocel.2019.01.016DOI Listing
April 2019

Method Protocols for Metabolic and Functional Analysis of the BRIN-BD11 β-Cell Line: A Preclinical Model for Type 2 Diabetes.

Methods Mol Biol 2019 ;1916:329-340

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia.

In type 2 diabetes, prolonged dysregulation of signalling and β-cell metabolic control leads to β-cell dysfunction, and is increasingly associated with abnormal metabolic states which disrupt normal cellular physiology. Utilization of appropriate β-cell models enables a systematic approach to understand the impact of perturbations to the biological system. The BRIN-BD11 β-cell line is a useful, pre-clinical cell model for β-cell dysfunction associated with type 2 diabetes, among other metabolic disorders. The present chapter describes detection and analysis of β-cell dysfunction with respect to changes in bioenergetics and metabolism, generation of intracellular reactive oxygen species, and acute and chronic insulin secretion in the BRIN-BD11 cell line.
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http://dx.doi.org/10.1007/978-1-4939-8994-2_32DOI Listing
June 2019

Pleiotropic Effects of GLP-1 and Analogs on Cell Signaling, Metabolism, and Function.

Front Endocrinol (Lausanne) 2018 23;9:672. Epub 2018 Nov 23.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia.

The incretin hormone Glucagon-Like Peptide-1 (GLP-1) is best known for its "incretin effect" in restoring glucose homeostasis in diabetics, however, it is now apparent that it has a broader range of physiological effects in the body. Both and studies have demonstrated that GLP-1 mimetics alleviate endoplasmic reticulum stress, regulate autophagy, promote metabolic reprogramming, stimulate anti-inflammatory signaling, alter gene expression, and influence neuroprotective pathways. A substantial body of evidence has accumulated with respect to how GLP-1 and its analogs act to restore and maintain normal cellular functions. These findings have prompted several clinical trials which have reported GLP-1 analogs improve cardiac function, restore lung function and reduce mortality in patients with obstructive lung disease, influence blood pressure and lipid storage, and even prevent synaptic loss and neurodegeneration. Mechanistically, GLP-1 elicits its effects via acute elevation in cAMP levels, and subsequent protein kinase(s) activation, pathways well-defined in pancreatic β-cells which stimulate insulin secretion in conjunction with elevated Ca and ATP. More recently, new studies have shed light on additional downstream pathways stimulated by chronic GLP-1 exposure, findings which have direct relevance to our understanding of the potential therapeutic effects of longer lasting analogs recently developed for clinical use. In this review, we provide a comprehensive description of the diverse roles for GLP-1 across multiple tissues, describe downstream pathways stimulated by acute and chronic exposure, and discuss novel pleiotropic applications of GLP-1 mimetics in the treatment of human disease.
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http://dx.doi.org/10.3389/fendo.2018.00672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266510PMC
November 2018

The effects of a combined bodyweight-based and elastic bands resistance training, with or without protein supplementation, on muscle mass, signaling and heat shock response in healthy older people.

Exp Gerontol 2019 01 5;115:104-113. Epub 2018 Dec 5.

Institute for Sport & Health, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Ireland; Food for Health Ireland, University College Dublin, Ireland. Electronic address:

This investigation sought to determine the effects of twelve weeks of resistance exercise training in addition to protein supplementation on body composition, markers of muscle atrophy/hypertrophy and heat shock response (HSR) in healthy older adults. Thirty-eight healthy sedentary participants (M/F, 18/20; age, 63.5 ± 4.4 y) were randomly assigned to four groups: I) PLACEBO: no training, receiving placebo sachets; II) NUTRITION: no training, receiving protein supplementation sachets; III) EXERCISE PLACEBO: training, placebo sachets and IV) EXERCISE NUTRITION: training, receiving protein sachets. The resistance training (using bodyweight and elastic bands) consisted of 45 min supervised training sessions, 3×/week. Participants from both exercise groups increased their total lean body mass (from 48.4 ± 8.7 to 49.2 ± 8.7 kg and from 44.9 ± 7.8 to 45.9 ± 8.1 kg, average of gain ~0.8 and 1 kg, placebo and nutrition respectively) and improved results in physical tests. Exercise nutrition group also reduced their body fat (from 34.8 ± 7.3 to 32.9 ± 7.4%), increased the expression of proteins/gene involved on the HSR, S6 and eEF2, while FOXO3 and Murf1 were reduced. Expression of MHC-I was reduced in both exercise groups while MHC-IIa increased, with no effect of protein supplementation alone. Body-weight and elastic bands based resistance exercise prompted, in healthy older people, improvements in body composition and muscle function. When protein supplementation was added to the people engaged in resistance training, improvements in fat mass and changes in skeletal muscle signaling were detected, favoring protein synthesis pathways and the protective heat shock response.
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http://dx.doi.org/10.1016/j.exger.2018.12.004DOI Listing
January 2019

The Role of Cystinosin in the Intermediary Thiol Metabolism and Redox Homeostasis in Kidney Proximal Tubular Cells.

Antioxidants (Basel) 2018 Dec 3;7(12). Epub 2018 Dec 3.

Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin 4, Ireland.

Cystinosin is a lysosomal transmembrane protein which facilitates transport of the disulphide amino acid cystine (CySS) from the lysosomes of the cell. This protein is encoded by the CTNS gene which is defective in the lysosomal storage disorder, cystinosis. Because of the apparent involvement of cystinosin in the intermediary thiol metabolism, its discovery has fuelled investigations into its role in modulating cellular redox homeostasis. The kidney proximal tubular cells (PTCs) have become the focus of various studies on cystinosin since the protein is highly expressed in these cells and kidney proximal tubular transport dysfunction is the foremost clinical manifestation of cystinosis. The lysosomal CySS pool is a major source of cytosolic cysteine (Cys), the limiting amino acid for the synthesis of an important antioxidant glutathione (GSH) via the γ-glutamyl cycle. Therefore, loss of cystinosin function is presumed to lead to cytosolic deficit of Cys which may impair GSH synthesis. However, studies using in vitro models lacking cystinosin yielded inconsistent results and failed to establish the mechanistic role of cystinosin in modulating GSH synthesis and redox homeostasis. Because of the complexity of the metabolic micro- and macro-environment in vivo, using in vitro models alone may not be able to capture the complete sequence of biochemical and physiological events that occur as a consequence of loss of cystinosin function. The coexistence of pathways for the overall handling and disposition of GSH, the modulation of CTNS gene by intracellular redox status and the existence of a non-canonical isoform of cystinosin may constitute possible rescue mechanisms in vivo to remediate redox perturbations in renal PTCs. Importantly, the mitochondria seem to play a critical role in orchestrating redox imbalances initiated by cystinosin dysfunction. Non-invasive techniques such as in vivo magnetic resonance imaging with the aid of systems biology approaches may provide invaluable mechanistic insights into the role of cystinosin in the essential intermediary thiol metabolism and in the overall regulation cellular redox homeostasis.
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http://dx.doi.org/10.3390/antiox7120179DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6315507PMC
December 2018

Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation.

Nutrients 2018 Oct 23;10(11). Epub 2018 Oct 23.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Biosciences, Curtin University, Perth 6102, Australia.

Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities, and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver, and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to the impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g., ill/critically ill, post-trauma, sepsis, exhausted athletes), it is currently difficult to determine whether glutamine supplementation (oral/enteral or parenteral) should be recommended based on the amino acid plasma/bloodstream concentration (also known as glutaminemia). Although the beneficial immune-based effects of glutamine supplementation are already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review of how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism and action, and important issues related to the effects of glutamine supplementation in catabolic situations.
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http://dx.doi.org/10.3390/nu10111564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266414PMC
October 2018

Lupin seed hydrolysate promotes G-protein-coupled receptor, intracellular Ca and enhanced glycolytic metabolism-mediated insulin secretion from BRIN-BD11 pancreatic beta cells.

Mol Cell Endocrinol 2019 01 19;480:83-96. Epub 2018 Oct 19.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute Biosciences, Curtin University, Perth, WA, 6102, Australia. Electronic address:

Lupin seed proteins have been reported to exhibit hypoglycaemic effects in animals and humans following oral administration, however little is known about its mechanism of action. This study investigated the signalling pathway(s) responsible for the insulinotropic effect of the hydrolysate obtained from lupin (Lupinus angustifolius L.) seed extracts utilizing BRIN-BD11 β-cells. The extract was treated with digestive enzymes to give a hydrolysate rich in biomolecules ≤7 kDa. Cells exhibited hydrolysate induced dose-dependent stimulation of insulin secretion and enhanced intracellular Ca and glucose metabolism. The stimulatory effect of the hydrolysate was potentiated by depolarizing concentrations of KCl and was blocked by inhibitors of the ATP sensitive K channel, Gα protein, phospholipase C (PLC) and protein kinase C (PKC). These findings reveal a novel mechanism for lupin hydrolysate stimulated insulin secretion via Gα mediated signal transduction (Gα/PLC/PKC) in the β-cells. Thus, lupin hydrolysates may have potential for nutraceutical treatment in type 2 diabetes.
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http://dx.doi.org/10.1016/j.mce.2018.10.015DOI Listing
January 2019

Inducible nitric oxide synthase inhibitor 1400W increases Na ,K -ATPase levels and activity and ameliorates mitochondrial dysfunction in Ctns null kidney proximal tubular epithelial cells.

Clin Exp Pharmacol Physiol 2018 11 30;45(11):1149-1160. Epub 2018 Jul 30.

Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.

Nitric oxide (NO) has been shown to play an important role in renal physiology and pathophysiology partly through its influence on various transport systems in the kidney proximal tubule. The role of NO in kidney dysfunction associated with lysosomal storage disorder, cystinosis, is largely unknown. In the present study, the effects of inducible nitric oxide synthase (iNOS)-specific inhibitor, 1400W, on Na ,K -ATPase activity and expression, mitochondrial integrity and function, nutrient metabolism, and apoptosis were investigated in Ctns null proximal tubular epithelial cells (PTECs). Ctns null PTECs exhibited an increase in iNOS expression, augmented NO and nitrite/nitrate production, and reduced Na ,K -ATPase expression and activity. In addition, these cells displayed depolarized mitochondria, reduced adenosine triphosphate content, altered nutrient metabolism, and elevated apoptosis. Treatment of Ctns null PTECs with 1400W abolished these effects which culminated in the mitigation of apoptosis in these cells. These findings indicate that uncontrolled NO production may constitute the upstream event that leads to the molecular and biochemical alterations observed in Ctns null PTECs and may explain, at least in part, the generalized proximal tubular dysfunction associated with cystinosis. Further studies are needed to realize the potential benefits of anti-nitrosative therapies in improving renal function and/or attenuating renal injury in cystinosis.
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http://dx.doi.org/10.1111/1440-1681.12998DOI Listing
November 2018

Oleoyl-lysophosphatidylinositol enhances glucagon-like peptide-1 secretion from enteroendocrine L-cells through GPR119.

Biochim Biophys Acta Mol Cell Biol Lipids 2018 09 5;1863(9):1132-1141. Epub 2018 Jun 5.

Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, E1 2AT London, United Kingdom; Metabolic Signalling Group, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia 6102, Australia. Electronic address:

The gastrointestinal tract is increasingly viewed as critical in controlling glucose metabolism, because of its role in secreting multiple glucoregulatory hormones, such as glucagon like peptide-1 (GLP-1). Here we investigate the molecular pathways behind the GLP-1- and insulin-secreting capabilities of a novel GPR119 agonist, Oleoyl-lysophosphatidylinositol (Oleoyl-LPI). Oleoyl-LPI is the only LPI species able to potently stimulate the release of GLP-1 in vitro, from murine and human L-cells, and ex-vivo from murine colonic primary cell preparations. Here we show that Oleoyl-LPI mediates GLP-1 secretion through GPR119 as this activity is ablated in cells lacking GPR119 and in colonic primary cell preparation from GPR119 mice. Similarly, Oleoyl-LPI-mediated insulin secretion is impaired in islets isolated from GPR119 mice. On the other hand, GLP-1 secretion is not impaired in cells lacking GPR55 in vitro or in colonic primary cell preparation from GPR55 mice. We therefore conclude that GPR119 is the Oleoyl-LPI receptor, upstream of ERK1/2 and cAMP/PKA/CREB pathways, where primarily ERK1/2 is required for GLP-1 secretion, while CREB activation appears dispensable.
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http://dx.doi.org/10.1016/j.bbalip.2018.06.007DOI Listing
September 2018

Casein Hydrolysate with Glycemic Control Properties: Evidence from Cells, Animal Models, and Humans.

J Agric Food Chem 2018 May 24;66(17):4352-4363. Epub 2018 Apr 24.

Evidence exists to support the role of dairy derived proteins whey and casein in glycemic management. The objective of the present study was to use a cell screening method to identify a suitable casein hydrolysate and to examine its ability to impact glycemia related parameters in an animal model and in humans. Following screening for the ability to stimulate insulin secretion in pancreatic beta cells, a casein hydrolysate was selected and further studied in the ob/ob mouse model. An acute postprandial study was performed in 62 overweight and obese adults. Acute and long-term supplementation with the casein hydrolysate in in vivo studies in mice revealed a glucose lowering effect and a lipid reducing effect of the hydrolysate (43% reduction in overall liver fat). The postprandial human study revealed a significant increase in insulin secretion ( p = 0.04) concomitant with a reduction in glucose ( p = 0.03). The area under the curve for the change in glucose decreased from 181.84 ± 14.6 to 153.87 ± 13.02 ( p = 0.009). Overall, the data supports further work on the hydrolysate to develop into a functional food product.
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http://dx.doi.org/10.1021/acs.jafc.7b05550DOI Listing
May 2018

The Influence of Breast Tumour-Derived Factors and Wnt Antagonism on the Transformation of Adipose-Derived Mesenchymal Stem Cells into Tumour-Associated Fibroblasts.

Cancer Microenviron 2018 Jun 10;11(1):71-84. Epub 2018 Apr 10.

Stem Cell and Cancer Biology Laboratory, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA, 6102, Australia.

Within the tumour stroma, a heterogeneous population of cell types reciprocally regulates cell proliferation, which considerably affects the progression of the disease. In this study, using tumour conditioned medium (TCM) derived from breast tumour cell lines - MCF7 and MDA MB 231, we have demonstrated the differentiation of adipose-derived mesenchymal stem cells (ADSCs) into tumour-associated fibroblasts (TAFs). Since the Wnt signalling pathway is a key signalling pathway driving breast tumour growth, the effect of the Wnt antagonist secreted frizzled-related protein 4 (sFRP4) was also examined. The response of ADSCs to TCM and sFRP4 treatments was determined by using cell viability assay to determine the changes in ADSC viability, immunofluorescence for mesenchymal markers, glucose uptake assay, and glycolysis stress test using the Seahorse Extracellular Flux analyser to determine the glycolytic activity of ADSCs. ADSCs have been shown to acquire a hyper-proliferative state, significantly increasing their number upon short-term and long-term exposure to TCM. Changes have also been observed in the expression of key mesenchymal markers as well as in the metabolic state of ADSCs. SFRP4 significantly inhibited the differentiation of ADSCs into TAFs by reducing cell growth as well as mesenchymal marker expression (cell line-dependent). However, sFRP4 did not induce further significant changes to the altered metabolic phenotype of ADSCs following TCM exposure. Altogether, this study suggests that the breast tumour milieu may transform ADSCs into a tumour-supportive phenotype, which can be altered by Wnt antagonism, but is independent of metabolic changes.
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http://dx.doi.org/10.1007/s12307-018-0210-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6008265PMC
June 2018

Role of the cell membrane interface in modulating production and uptake of Alzheimer's beta amyloid protein.

Biochim Biophys Acta Biomembr 2018 Sep 21;1860(9):1639-1651. Epub 2018 Mar 21.

Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical and Health Sciences, Edith Cowan University, Australia; School of Biomedical Science, Macquarie University, Australia; School of Psychiatry and Clinical Neurosciences, University of Western Australia, Australia.

The beta amyloid protein (Aβ) plays a central role in Alzheimer's disease (AD) pathogenesis and its interaction with cell membranes in known to promote mutually disruptive structural perturbations that contribute to amyloid deposition and neurodegeneration in the brain. In addition to protein aggregation at the membrane interface and disruption of membrane integrity, growing reports demonstrate an important role for the membrane in modulating Aβ production and uptake into cells. The aim of this review is to highlight and summarize recent literature that have contributed insight into the implications of altered membrane composition on amyloid precursor protein (APP) proteolysis, production of Aβ, its internalization in to cells via permeabilization and receptor mediated uptake. Here, we also review the various membrane model systems and experimental tools used for probing Aβ-membrane interactions to investigate the key mechanistic aspects underlying the accumulation and toxicity of Aβ in AD.
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http://dx.doi.org/10.1016/j.bbamem.2018.03.015DOI Listing
September 2018

Epigenetic effects of metformin: From molecular mechanisms to clinical implications.

Diabetes Obes Metab 2018 07 22;20(7):1553-1562. Epub 2018 Mar 22.

School of Pharmacy and Biomedical Sciences, and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia.

There is a growing body of evidence that links epigenetic modifications to type 2 diabetes. Researchers have more recently investigated effects of commonly used medications, including those prescribed for diabetes, on epigenetic processes. This work reviews the influence of the widely used antidiabetic drug metformin on epigenomics, microRNA levels and subsequent gene expression, and potential clinical implications. Metformin may influence the activity of numerous epigenetic modifying enzymes, mostly by modulating the activation of AMP-activated protein kinase (AMPK). Activated AMPK can phosphorylate numerous substrates, including epigenetic enzymes such as histone acetyltransferases (HATs), class II histone deacetylases (HDACs) and DNA methyltransferases (DNMTs), usually resulting in their inhibition; however, HAT1 activity may be increased. Metformin has also been reported to decrease expression of multiple histone methyltransferases, to increase the activity of the class III HDAC SIRT1 and to decrease the influence of DNMT inhibitors. There is evidence that these alterations influence the epigenome and gene expression, and may contribute to the antidiabetic properties of metformin and, potentially, may protect against cancer, cardiovascular disease, cognitive decline and aging. The expression levels of numerous microRNAs are also reportedly influenced by metformin treatment and may confer antidiabetic and anticancer activities. However, as the reported effects of metformin on epigenetic enzymes act to both increase and decrease histone acetylation, histone and DNA methylation, and gene expression, a significant degree of uncertainty exists concerning the overall effect of metformin on the epigenome, on gene expression, and on the subsequent effect on the health of metformin users.
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http://dx.doi.org/10.1111/dom.13262DOI Listing
July 2018

Attenuation of obesity and insulin resistance by fish oil supplementation is associated with improved skeletal muscle mitochondrial function in mice fed a high-fat diet.

J Nutr Biochem 2018 05 11;55:76-88. Epub 2017 Dec 11.

Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil; Institute of Physical Activity Sciences and Sports, Cruzeiro do Sul University, Sao Paulo, Brazil. Electronic address:

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to improve insulin sensitivity and glucose homeostasis in animal models of insulin resistance, but the involved mechanisms still remain unresolved. In this study, we evaluated the effects of fish oil (FO), a source of n-3 PUFAs, on obesity, insulin resistance and muscle mitochondrial function in mice fed a high-fat diet (HFD). C57Bl/6 male mice, 8 weeks old, were divided into four groups: control diet (C), high-fat diet (H), C+FO (CFO) and H+FO (HFO). FO was administered by oral gavage (2 g/kg b.w.), three times a week, starting 4 weeks before diet administration until the end of the experimental protocol. HFD-induced obesity and insulin resistance associated with impaired skeletal muscle mitochondrial function, as indicated by decreased oxygen consumption, tricarboxylic acid cycle intermediate (TCAi) contents (citrate, α-ketoglutarate, malate and oxaloacetate), oxidative phosphorylation protein content and mitochondrial biogenesis. These effects were associated with elevated reactive oxygen species production, decreased PGC1-a transcription and reduced Akt phosphorylation. The changes induced by the HFD were partially attenuated by FO, which decreased obesity and insulin resistance and increased mitochondrial function. In the H group, FO supplementation also improved oxygen consumption; increased TCAi content, and Akt and AMPK phosphorylation; and up-regulated mRNA expression of Gpat1, Pepck, catalase and mitochondrial proteins (Pgc1α, Pparα, Cpt1 and Ucp3). These results suggest that dietary FO attenuates the deleterious effects of the HFD (obesity and insulin resistance) by improving skeletal muscle mitochondrial function.
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http://dx.doi.org/10.1016/j.jnutbio.2017.11.012DOI Listing
May 2018