Publications by authors named "Sean L McGee"

88 Publications

1-Methyl-1-pyrazole-5-carboxamide Derivatives Exhibit Unexpected Acute Mammalian Toxicity.

J Med Chem 2021 01 22;64(1):840-844. Epub 2020 Dec 22.

School of Pharmaceutical Sciences, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China.

A series of 1-methyl-1-pyrazole-5-carboxamides were synthesized as potent inhibitors of the parasitic nematode of sheep, . These compounds did not show overt cytotoxicity to a range of mammalian cell lines under standard in vitro culture conditions, had high selectivity indices, and were progressed to an acute toxicity study in a rodent model. Strikingly, acute toxicity was observed in mice. Experiments measuring cellular respiration showed a dose-dependent inhibition of mitochondrial respiration. Under these conditions, potent cytotoxicity was observed for these compounds in rat hepatocytes suggesting that the potent acute mammalian toxicity of this chemotype is most likely associated with respiratory inhibition. In contrast, parasite toxicity was not correlated to acute toxicity or cytotoxicity in respiring cells. This paper highlights the importance of identifying an appropriate in vitro predictor of in vivo toxicity early on in the drug discovery pipeline, in particular assessment for in vitro mitochondrial toxicity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jmedchem.0c01793DOI Listing
January 2021

Loss of protein kinase D activity demonstrates redundancy in cardiac glucose metabolism and preserves cardiac function in obesity.

Mol Metab 2020 12 21;42:101105. Epub 2020 Oct 21.

Institute for Mental and Physical Health and Clinical Translation, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia. Electronic address:

Objective: Protein kinase D (PKD) signaling has been implicated in stress-induced cardiac remodeling and function as well as metabolic processes including contraction-mediated cardiac glucose uptake. PKD has recently emerged as a nutrient-sensing kinase that is activated in high-lipid environments, such as in obesity. However, the role of PKD signaling in cardiac glucose metabolism and cardiac function in both normal and obese conditions remains unknown.

Methods: A cardiac-specific and inducible dominant negative (DN) PKD mouse model was developed. Echocardiography was used to assess cardiac function, while metabolic phenotyping was performed, including stable isotope metabolomics on cardiac tissue in mice fed either regular chow or a high-fat diet (43% calories from fat).

Results: Cardiac PKD activity declined by ∼90% following DN PKD induction in adult mice. The mice had diminished basal cardiac glucose clearance, suggesting impaired contraction-mediated glucose uptake, but normal cardiac function. In obesity studies, systolic function indices were reduced in control mice, but not in cardiac DN PKD mice. Using targeted stable isotope metabolomic analyses, no differences in glucose flux through glycolysis or the TCA cycle were observed between groups.

Conclusions: The data show that PKD contributes to cardiac dysfunction in obesity and highlight the redundancy in cardiac glucose metabolism that maintains cardiac glucose flux in vivo. The data suggest that impairments in contraction-mediated glucose uptake are unlikely to drive cardiac dysfunction in both normal and metabolic disease states.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.molmet.2020.101105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7680779PMC
December 2020

The role of protein kinase D (PKD) in intracellular nutrient sensing and regulation of adaptive responses to the obese environment.

Obes Rev 2021 03 14;22(3):e13145. Epub 2020 Sep 14.

Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Australia.

Obesity is associated with ectopic accumulation of lipids, which is implicated in the development of insulin resistance, type 2 diabetes mellitus and cardiovascular disease. As the global prevalence of obesity continues to rise, it is becoming increasingly important to understand the underlying cellular mechanisms of this disease. Protein kinase D (PKD) is an intracellular signalling kinase with well characterized roles in intracellular vesicle transport and secretion, cancer cell proliferation and cardiac hypertrophy. However, emerging evidence also highlights PKD as a novel nutrient sensor. PKD activation is mediated by the accumulation of the lipid intermediate diacylglycerol, and PKD activity in the liver, heart and adipose tissue increases upon feeding. In obesity, PKD signalling is linked to reduced insulin signalling and dysfunction in adipose tissue, liver and heart, whilst in the pancreas, PKD is essential for the compensatory increase in glucose-stimulated insulin secretion from β-cells during obesity. Collectively, these studies reveal aspects of PKD signalling that are involved in the tissue-specific responses to obesity. This review summarizes the emerging evidence suggesting that PKD plays an important role in regulating the adaptive response to the obese environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/obr.13145DOI Listing
March 2021

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review.

J Shoulder Elbow Surg 2021 Jan 19;30(1):200-215. Epub 2020 Aug 19.

School of Medicine, Deakin University, Geelong, VIC, Australia; Barwon Centre for Orthopaedic Research & Education (B-CORE), St John of God Hospital and Barwon Health, Geelong, VIC, Australia.

Background: Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

Methods: A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

Results: The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

Conclusion: This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2020.07.045DOI Listing
January 2021

Publisher Correction: Integrated analysis of a compendium of RNA-Seq datasets for splicing factors.

Sci Data 2020 08 7;7(1):267. Epub 2020 Aug 7.

Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41597-020-00607-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414123PMC
August 2020

Reducing hepatic PKD activity lowers circulating VLDL cholesterol.

J Endocrinol 2020 09;246(3):265-276

Institute for Mental and Physical Health and Clinical Translation (iMPACT) and Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia.

Protein kinase D (PKD) is emerging as an important kinase regulating energy balance and glucose metabolism; however, whether hepatic PKD activity can be targeted to regulate these processes is currently unclear. In this study, hepatic PKD activity was reduced using adeno-associated virus vectors to express a dominant-negative (DN) version of PKD1, which impairs the action of all three PKD isoforms. In chow-fed mice, hepatic DN PKD expression increased whole-body glucose oxidation, but had only mild effects on glucose and insulin tolerance and no effects on glucose homeostasis following fasting and refeeding. However, circulating VLDL cholesterol was reduced under these conditions and was associated with hepatic fatty acid accumulation, but not lipids involved in lipoprotein synthesis. The limited effects on glucose homeostasis in DN PKD mice was despite reduced expression of gluconeogenic genes under both fasted and refed conditions, and enhanced pyruvate tolerance. The requirement for PKD for gluconeogenic capacity was supported by in vitro studies in cultured FAO hepatoma cells expressing DN PKD, which produced less glucose under basal conditions. Although these pathways are increased in obesity, the expression of DN PKD in the liver of mice fed a high-fat diet had no impact on glucose tolerance, insulin action, pyruvate tolerance or plasma VLDL. Together, these data suggest that PKD signalling in the liver regulates metabolic pathways involved in substrate redistribution under conditions of normal nutrient availability, but not under conditions of overnutrition such as in obesity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1530/JOE-19-0548DOI Listing
September 2020

Exercise adaptations: molecular mechanisms and potential targets for therapeutic benefit.

Nat Rev Endocrinol 2020 09 6;16(9):495-505. Epub 2020 Jul 6.

Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia.

Exercise is fundamental for good health, whereas physical inactivity underpins many chronic diseases of modern society. It is well appreciated that regular exercise improves metabolism and the metabolic phenotype in a number of tissues. The phenotypic alterations observed in skeletal muscle are partly mediated by transcriptional responses that occur following each individual bout of exercise. This adaptive response increases oxidative capacity and influences the function of myokines and extracellular vesicles that signal to other tissues. Our understanding of the epigenetic and transcriptional mechanisms that mediate the skeletal muscle gene expression response to exercise as well as of their upstream signalling pathways has advanced substantially in the past 10 years. With this knowledge also comes the opportunity to design new therapeutic strategies based on the biology of exercise for a variety of chronic conditions where regular exercise might be a challenge. This Review provides an overview of the beneficial adaptive responses to exercise and details the molecular mechanisms involved. The possibility of designing therapeutic interventions based on these molecular mechanisms is addressed, using relevant examples that have exploited this approach.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41574-020-0377-1DOI Listing
September 2020

Exercise and GLUT4.

Exerc Sport Sci Rev 2020 07;48(3):110-118

Department of Physiology, The University of Melbourne, Melbourne, Australia.

The glucose transporter GLUT4 is critical for skeletal muscle glucose uptake in response to insulin and muscle contraction/exercise. Exercise increases GLUT4 translocation to the sarcolemma and t-tubule and, over the longer term, total GLUT4 protein content. Here, we review key aspects of GLUT4 biology in relation to exercise, with a focus on exercise-induced GLUT4 translocation, postexercise metabolism and muscle insulin sensitivity, and exercise effects on GLUT4 expression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1249/JES.0000000000000224DOI Listing
July 2020

Integrated analysis of a compendium of RNA-Seq datasets for splicing factors.

Sci Data 2020 06 16;7(1):178. Epub 2020 Jun 16.

Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA.

A vast amount of public RNA-sequencing datasets have been generated and used widely to study transcriptome mechanisms. These data offer precious opportunity for advancing biological research in transcriptome studies such as alternative splicing. We report the first large-scale integrated analysis of RNA-Seq data of splicing factors for systematically identifying key factors in diseases and biological processes. We analyzed 1,321 RNA-Seq libraries of various mouse tissues and cell lines, comprising more than 6.6 TB sequences from 75 independent studies that experimentally manipulated 56 splicing factors. Using these data, RNA splicing signatures and gene expression signatures were computed, and signature comparison analysis identified a list of key splicing factors in Rett syndrome and cold-induced thermogenesis. We show that cold-induced RNA-binding proteins rescue the neurite outgrowth defects in Rett syndrome using neuronal morphology analysis, and we also reveal that SRSF1 and PTBP1 are required for energy expenditure in adipocytes using metabolic flux analysis. Our study provides an integrated analysis for identifying key factors in diseases and biological processes and highlights the importance of public data resources for identifying hypotheses for experimental testing.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41597-020-0514-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7297722PMC
June 2020

Effects of psychoactive drugs on cellular bioenergetic pathways.

World J Biol Psychiatry 2021 02 29;22(2):79-93. Epub 2020 Apr 29.

Centre for Molecular and Medical Research, School of Medicine, Deakin University, Geelong, Australia.

Objectives: To investigate the actions of lithium, valproate, lamotrigine and quetiapine on bioenergetic pathways in cultured NT2-N neuronal-like cells and C8-B4 microglial cells.

Methods: NT2-N and C8-B4 cells were cultured and treated with lithium (2.5 mM), valproate (0.5 mM), quetiapine (0.05 mM) or lamotrigine (0.05 mM) for 24 hours. Gene expression and the mitochondrial bioenergetic profile were measured in both cell lines.

Results: In NT2-N cells, valproate increased oxidative phosphorylation (OXPHOS) gene expression, mitochondrial uncoupling and maximal respiratory capacity, while quetiapine decreased OXPHOS gene expression and respiration linked to ATP turnover, as well as decreasing the expression of genes in the citric acid cycle. Lamotrigine decreased OXPHOS gene expression but had no effect on respiration, while lithium reduced the expression of genes in the citric acid cycle. In C8-B4 cells, valproate and lithium increased OXPHOS gene expression, and valproate increased basal respiratory rate and maximal and spare respiratory capacities. In contrast, quetiapine significantly reduced basal respiratory rate and maximal and spare respiratory capacities.

Conclusions: Overall our data suggest that some drugs used to treat neuropsychiatric and affective disorders have actions on a range of cellular bioenergetic processes, which could impact their effects in patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/15622975.2020.1755450DOI Listing
February 2021

Transcriptomic analysis of adhesive capsulitis of the shoulder.

J Orthop Res 2020 10 17;38(10):2280-2289. Epub 2020 Apr 17.

School of Medicine and Centre for Molecular and Medical Research, Deakin University, Waurn Ponds, Geelong, Australia.

Adhesive capsulitis (AC) is a disabling condition of the shoulder joint affecting 2 to 5% of the general population. Our understanding of the molecular mechanisms is limited. The present study aimed to determine potential biomarkers of AC through transcriptomic analysis. This multi-centre study investigated patients undergoing arthroscopic capsulotomy surgery for resistant AC compared to those undergoing arthroscopic stabilization surgery for glenohumeral instability (control). Tissue samples were harvested from the anterior capsule during surgery. Total RNA was extracted and RNA-sequencing-based transcriptomics were performed. A number of genes deemed differentially expressed in RNA-sequencing analysis were validated using real-time reverse transcription polymerase chain reaction (RT-PCR). Baseline characteristics of the AC group (n = 22) were; mean age 52.7 years (SD: 10.2), 73% female, and Oxford Shoulder Score 19.6 (SD: 8.0), compared with the control group (n = 26), average age 23.9 years (SD: 5.2), 15% female, and Oxford Shoulder Score 39.0 (SD: 7.4). Transcriptomic analysis with false discovery rate correction and log fold change cut-off of ±1.5 revealed 545 differentially expressed genes in AC relative to control. Bioinformatic analyses were carried out to identify biological processes and pathways enriched in this dataset. Real-time RT-PCR using two different normalization processes confirmed increased expression of matrix metallopeptidase 13 (MMP13) and platelet-derived growth factor subunit B (PDGFB), in patients with AC, while tumor necrosis factor α (TNFA) expression was reduced. These findings provide a comprehensive assessment of transcriptional changes associated with AC that give insights into the aetiology of the disease and provides a resource for molecular targets to better diagnose and treat this condition.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jor.24686DOI Listing
October 2020

Intravascular Follistatin gene delivery improves glycemic control in a mouse model of type 2 diabetes.

FASEB J 2020 04 5;34(4):5697-5714. Epub 2020 Mar 5.

Centre for Muscle Research, Department of Physiology, The University of Melbourne, Parkville, VIC, Australia.

Type 2 diabetes (T2D) manifests from inadequate glucose control due to insulin resistance, hypoinsulinemia, and deteriorating pancreatic β-cell function. The pro-inflammatory factor Activin has been implicated as a positive correlate of severity in T2D patients, and as a negative regulator of glucose uptake by skeletal muscle, and of pancreatic β-cell phenotype in mice. Accordingly, we sought to determine whether intervention with the Activin antagonist Follistatin can ameliorate the diabetic pathology. Here, we report that an intravenous Follistatin gene delivery intervention with tropism for striated muscle reduced the serum concentrations of Activin B and improved glycemic control in the db/db mouse model of T2D. Treatment reversed the hyperglycemic progression with a corresponding reduction in the percentage of glycated-hemoglobin to levels similar to lean, healthy mice. Follistatin gene delivery promoted insulinemia and abundance of insulin-positive pancreatic β-cells, even when treatment was administered to mice with advanced diabetes, supporting a mechanism for improved glycemic control associated with maintenance of functional β-cells. Our data demonstrate that single-dose intravascular Follistatin gene delivery can ameliorate the diabetic progression and improve prognostic markers of disease. These findings are consistent with other observations of Activin-mediated mechanisms exerting deleterious effects in models of obesity and diabetes, and suggest that interventions that attenuate Activin signaling could help further understanding of T2D and the development of novel T2D therapeutics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.201802059RRRDOI Listing
April 2020

A systematic flux analysis approach to identify metabolic vulnerabilities in human breast cancer cell lines.

Cancer Metab 2019 27;7:12. Epub 2019 Dec 27.

Metabolic Reprogramming Laboratory, Metabolic Research Unit, School of Medicine and Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria Australia.

Background: Increased flux through both glycolytic and oxidative metabolic pathways is a hallmark of breast cancer cells and is critical for their growth and survival. As such, targeting this metabolic reprograming has received much attention as a potential treatment approach. However, the heterogeneity of breast cancer cell metabolism, even within classifications, suggests a necessity for an individualised approach to treatment in breast cancer patients.

Methods: The metabolic phenotypes of a diverse panel of human breast cancer cell lines representing the major breast cancer classifications were assessed using real-time metabolic flux analysis. Flux linked to ATP production, pathway reserve capacities and specific macromolecule oxidation rates were quantified. Suspected metabolic vulnerabilities were targeted with specific pathway inhibitors, and relative cell viability was assessed using the crystal violet assay. Measures of AMPK and mTORC1 activity were analysed through immunoblotting.

Results: Breast cancer cells displayed heterogeneous energy requirements and utilisation of non-oxidative and oxidative energy-producing pathways. Quantification of basal glycolytic and oxidative reserve capacities identified cell lines that were highly dependent on individual pathways, while assessment of substrate oxidation relative to total oxidative capacity revealed cell lines that were highly dependent on individual macromolecules. Based on these findings, mild mitochondrial inhibition in ESH-172 cells, including with the anti-diabetic drug metformin, and mild glycolytic inhibition in Hs578T cells reduced relative viability, which did not occur in non-transformed MCF10a cells. The effects on viability were associated with AMPK activation and inhibition of mTORC1 signalling. Hs578T were also found to be highly dependent on glutamine oxidation and inhibition of this process also impacted viability.

Conclusions: Together, these data highlight that systematic flux analysis in breast cancer cells can identify targetable metabolic vulnerabilities, despite heterogeneity in metabolic profiles between individual cancer cell lines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s40170-019-0207-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6935091PMC
December 2019

Identification of Fromiamycalin and Halaminol A from Australian Marine Sponge Extracts with Anthelmintic Activity against .

Mar Drugs 2019 Oct 23;17(11). Epub 2019 Oct 23.

Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.

There is an urgent need to discover and develop new anthelmintics for the treatment of parasitic nematodes of veterinary importance to circumvent challenges linked to drug resistant parasites. Being one of the most diverse natural ecosystems, the marine environment represents a rich resource of novel chemical entities. This study investigated 2000 extracts from marine invertebrates, collected from Australian waters, for anthelmintic activity. Using a well-established in vitro bioassay, these extracts were screened for nematocidal activity against -a socioeconomically important parasitic nematode of livestock animals. Extracts (designated -1, -1 and -2) from two marine sponges ( and sp.) each significantly affected larvae of . Individual extracts displayed a dose-dependent inhibition of both the motility of exsheathed third-stage larvae (xL3s) and the development of xL3s to fourth-stage larvae (L4s). Active fractions in each of the three extracts were identified using bioassay-guided fractionation. From the active fractions from , a known pentacyclic guanidine alkaloid, fromiamycalin (), was purified. This alkaloid was shown to be a moderately potent inhibitor of L4 development (half-maximum inhibitory concentration (IC) = 26.6 ± 0.74 µM) and L4 motility (IC = 39.4 ± 4.83 µM), although it had a relatively low potency at inhibiting of xL3 motility (IC ≥ 100 µM). Investigation of the active fractions from the two collections led to identification of a mixture of amino alcohol lipids, and, subsequently, a known natural product halaminol A (). Anthelmintic profiling showed that had limited potency at inhibiting larval development and motility. These data indicate that fromiamycalin, other related pentacyclic guanidine alkaloids and/or halaminols could have potential as anthelmintics following future medicinal chemistry efforts.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/md17110598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6891614PMC
October 2019

Modulation of high fat diet-induced microbiome changes, but not behaviour, by minocycline.

Brain Behav Immun 2019 11 4;82:309-318. Epub 2019 Sep 4.

School of Medicine, Centre for Molecular and Medical Research, Deakin University, Geelong, Australia; The Florey Institute of Neuroscience and Mental Health, Parkville, Australia. Electronic address:

An emerging novel therapeutic agent for major depressive disorder, minocycline, has the potential to influence both gut microbiome and inflammatory status. The present study showed that chronic high fat diet feeding led to changes in both behaviour and the gut microbiome in male mice, without an overt inflammatory response. The diet-induced behavioural changes were characterised as increased immobility in the forced swim test and changes in locomotor activities in the open field test. Minocycline significantly altered the gut microbiome, rendering a community distinctly different to both untreated healthy and diet-affected states. In contrast, minocycline did not reverse high fat diet-induced changes in behaviour.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbi.2019.09.001DOI Listing
November 2019

Phosphatidylserine decarboxylase is critical for the maintenance of skeletal muscle mitochondrial integrity and muscle mass.

Mol Metab 2019 09 27;27:33-46. Epub 2019 Jun 27.

Deakin University, Geelong, Australia; School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Burwood, Victoria, 3125, Australia. Electronic address:

Objective: Phosphatidylethanolamine (PtdEtn) is a major phospholipid in mammals. It is synthesized via two pathways, the CDP-ethanolamine pathway in the endoplasmic reticulum and the phosphatidylserine (PtdSer) decarboxylase (PSD) pathway in the mitochondria. While the CDP-ethanolamine pathway is considered the major route for PtdEtn synthesis in most mammalian tissues, little is known about the importance of the PSD pathway in vivo, especially in tissues enriched with mitochondria such as skeletal muscle. Therefore, we aimed to examine the role of the mitochondrial PSD pathway in regulating PtdEtn homeostasis in skeletal muscle in vivo.

Methods: To determine the functional significance of this pathway in skeletal muscle in vivo, an adeno-associated viral vector approach was employed to knockdown PSD expression in skeletal muscle of adult mice. Muscle lipid and metabolite profiling was performed using mass spectrometry.

Results: PSD knockdown disrupted muscle phospholipid homeostasis leading to an ∼25% reduction in PtdEtn and an ∼45% increase in PtdSer content. This was accompanied by the development of a severe myopathy, evident by a 40% loss in muscle mass as well as extensive myofiber damage as shown by increased DNA synthesis and central nucleation. In addition, PSD knockdown caused marked accumulation of abnormally appearing mitochondria that exhibited severely disrupted inner membrane integrity and reduced OXPHOS protein content.

Conclusions: The PSD pathway has a significant role in maintaining phospholipid homeostasis in adult skeletal muscle. Moreover, PSD is essential for maintenance of mitochondrial integrity and skeletal muscle mass.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.molmet.2019.06.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6717954PMC
September 2019

Epigenetics and Exercise.

Trends Endocrinol Metab 2019 09 3;30(9):636-645. Epub 2019 Jul 3.

Department of Physiology, The University of Melbourne, VIC 3010, Australia. Electronic address:

Epigenetics can be defined as 'the structural adaptation of chromosomal regions so as to register, signal, or perpetuate altered activity states.' Increased transcription of key regulatory, metabolic, and myogenic genes is an early response to exercise and is important in mediating subsequent adaptations in skeletal muscle. DNA hypomethylation and histone hyperacetylation are emerging as important crucial events for increased transcription. The complex interactions between multiple epigenetic modifications and their regulation by metabolic changes and signaling events during exercise, with implications for enhanced understanding of the acute and chronic adaptations to exercise, are questions for further investigation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.tem.2019.06.002DOI Listing
September 2019

Class IIa HDACs do not influence beta-cell function under normal or high glucose conditions.

Islets 2019 21;11(5):112-118. Epub 2019 May 21.

Metabolic Research Unit, School of Medicine, Deakin University , Waurn Ponds , Australia.

Inhibiting Class IIa Histone Deacetylase (HDAC) function is a promising approach to therapeutically enhance skeletal and cardiac muscle metabolic health in several chronic diseases including type 2 diabetes. However, the importance of Class IIa HDACs in the beta-cell remains unknown. As beta-cell function is vital to maintaining glycaemia it is essential that the importance of Class IIa HDACs in the beta-cell is determined. Here we used the INS-1E cell line cultured in normal glucose (11.1 mM) or hyperglycaemic (20 mM) conditions for 48 hrs to represent cells in a normal and diabetic environment respectively. Cells cultured in high glucose showed significantly reduced insulin secretory function and increased apoptotic signalling compared to cells cultured in normal glucose. Class IIa HDACS, HDAC-4 and -5, were not regulated at the transcript or protein level under normal or hyperglycaemic conditions suggesting that they may not play a role in beta-cell dysfunction. Furthermore, overexpression of wild-type HDAC-4 and -5 or dominant negative HDAC-4 and -5 did not alter insulin secretion, insulin mRNA expression or apoptotic signalling under normal or hyperglycaemic conditions. This suggests that Class IIa Histone Deacetylases do not play an important physiological role in the beta-cell under normal or diabetic conditions. Thus, Class IIa Histone Deacetylase inhibitors are not likely to have a detrimental effect on beta-cells supporting the use of these inhibitors to treat metabolic diseases such as type 2 diabetes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/19382014.2019.1617621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6773392PMC
March 2020

Genetic and epigenetic sex-specific adaptations to endurance exercise.

Epigenetics 2019 06 13;14(6):523-535. Epub 2019 Apr 13.

a Institute for Health and Sport (iHeS) , Victoria University , Melbourne , Australia.

In recent years, the interest in personalised interventions such as medicine, nutrition, and exercise is rapidly rising to maximize health outcomes and ensure the most appropriate treatments. Exercising regularly is recommended for both healthy and diseased populations to improve health. However, there are sex-specific adaptations to exercise that often are not taken into consideration. While endurance exercise training alters the human skeletal muscle epigenome and subsequent gene expression, it is still unknown whether it does so differently in men and women, potentially leading to sex-specific physiological adaptations. Elucidating sex differences in genetics, epigenetics, gene regulation and expression in response to exercise will have great health implications, as it may enable gene targets in future clinical interventions and may better individualised interventions. This review will cover this topic and highlight the recent findings of sex-specific genetic, epigenetic, and gene expression studies, address the gaps in the field, and offer recommendations for future research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/15592294.2019.1603961DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6557612PMC
June 2019

Adhesive capsulitis of the shoulder: protocol for the adhesive capsulitis biomarker (AdCaB) study.

BMC Musculoskelet Disord 2019 Apr 5;20(1):145. Epub 2019 Apr 5.

Barwon Centre for Orthopaedic Research and Education (B-CORE), Barwon Health, St John of God Hospital and Deakin University, PO Box 281, Geelong, 3220, Australia.

Background: Adhesive capsulitis (AC) is a disabling and poorly understood pathological condition of the shoulder joint. The current study aims to increase our understanding of the pathogenesis, diagnosis and clinical outcomes of people with AC by investigating: 1) transcriptome-wide alterations in gene expression of the glenohumeral joint capsule in people with AC compared to people with non-inflammatory shoulder instability (controls); 2) serum and urine biomarkers to better understand diagnosis and staging of AC; and 3) clinical outcomes in people with AC compared to controls 12-months following arthroscopic capsular release or labral repair respectively.

Methods: The study is a prospective multi-centre longitudinal study investigating people undergoing arthroscopic capsulotomy for AC compared to people undergoing arthroscopic stabilization for shoulder instability. Tissue samples collected from the anterior glenohumeral joint capsule during surgery will undergo RNA-seq to determine differences in gene expression between the study groups. Gene Set Enrichment Analysis will be used to further understand the pathogenesis of AC as well as guide serum and urine biomarker analysis. Clinical outcomes regarding pain, function and quality of life will be assessed using the Oxford Shoulder Score, Oxford Shoulder Instability Score, Quick DASH, American Shoulder and Elbow Society Score, EQ-5D-5 L and active shoulder range of movement. Clinical outcomes will be collected pre-operatively and 12-months post-operatively and study groups will be compared for statistically significant differences using linear regression, adjusting for baseline demographic variables.

Discussion: This study will provide much needed information regarding the pathogenesis, diagnosis and staging of AC. It will evaluate clinical outcomes for people undergoing arthroscopic release of AC by comparing this group to people undergoing arthroscopic surgery for shoulder instability.

Trial Registration: ACTRN12618000431224 , retrospectively registered 26 March 2018.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12891-019-2536-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6451260PMC
April 2019

A physiological drop in pH decreases mitochondrial respiration, and HDAC and Akt signaling, in L6 myocytes.

Am J Physiol Cell Physiol 2019 03 16;316(3):C404-C414. Epub 2019 Jan 16.

Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia.

Exercise stimulates mitochondrial biogenesis and increases mitochondrial respiratory function and content. However, during high-intensity exercise muscle pH can decrease below pH 6.8 with a concomitant increase in lactate concentration. This drop in muscle pH is associated with reduced exercise-induced mitochondrial biogenesis, while increased lactate may act as a signaling molecule to affect mitochondrial biogenesis. Therefore, in this study we wished to determine the impact of altering pH and lactate concentration in L6 myotubes on genes and proteins known to be involved in mitochondrial biogenesis. We also examined mitochondrial respiration in response to these perturbations. Differentiated L6 myotubes were exposed to normal (pH 7.5)-, low (pH 7.0)-, or high (pH 8.0)-pH media with and without 20 mM sodium l-lactate for 1 and 6 h. Low pH and 20 mM sodium l-lactate resulted in decreased Akt (Ser473) and AMPK (T172) phosphorylation at 1 h compared with controls, while at 6 h the nuclear localization of histone deacetylase 5 (HDAC5) was decreased. When the pH was increased both Akt (Ser473) and AMPK (T172) phosphorylation was increased at 1 h. Overall increased lactate decreased the nuclear content of HDAC5 at 6 h. Exposure to both high- and low-pH media decreased basal mitochondrial respiration, ATP turnover, and maximum mitochondrial respiratory capacity. These data indicate that muscle pH affects several metabolic signaling pathways, including those required for mitochondrial function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajpcell.00214.2018DOI Listing
March 2019

Exercise and GLUT4 in human subcutaneous adipose tissue.

Physiol Rep 2018 Nov;6(22):e13918

Department of Physiology, The University of Melbourne, Melbourne, Australia.

To examine the effect of acute and chronic exercise on adipose tissue GLUT4 expression, a total of 20 healthy, male subjects performed one of two studies. Ten subjects performed cycle ergometer exercise for 60 min at 73 ± 2% VO peak and abdominal adipose tissue samples were obtained immediately before and after exercise and after 3 h of recovery. Another 10 subjects completed 10 days of exercise training, comprising a combination of six sessions of 60 min at 75% VO peak and four sessions of 6 × 5 min at 90% VO peak, separated by 3 min at 40% VO peak. Abdominal adipose tissue and vastus lateralis muscle samples were obtained before training and 24 h after the last training session. A single bout of exercise did not change adipose tissue GLUT4 mRNA; however, there was a small, but significant, reduction in adipose tissue GLUT4 protein expression 3 h after exercise. There were no changes in adipose tissue GLUT4 or COX-IV expression following exercise training. In contrast, skeletal muscle GLUT4 and COX-IV were increased by 47% and 44%, respectively following exercise training. The exercise training-induced increase in GLUT4 expression was similar in both type I and type IIa single muscle fibers. Our results indicate that neither a single exercise bout, nor 10 days of exercise training, increased adipose tissue GLUT4, in contrast with the increases observed in skeletal muscle GLUT4 expression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.14814/phy2.13918DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6240583PMC
November 2018

Arylpyrrole and fipronil analogues that inhibit the motility and/or development of Haemonchus contortus in vitro.

Int J Parasitol Drugs Drug Resist 2018 12 4;8(3):379-385. Epub 2018 Jun 4.

Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

Due to widespread drug resistance in parasitic nematodes, there is a need to develop new anthelmintics. Given the cost and time involved in developing a new drug, the repurposing of known chemicals can be a promising, alternative approach. In this context, we tested a library (n = 600) of natural product-inspired pesticide analogues against exsheathed third stage-larvae (xL3s) of Haemonchus contortus (barber's pole worm) using a whole-organism, phenotypic screening technique that measures the inhibition of motility and development in treated larvae. In the primary screen, we identified 32 active analogues derived from chemical scaffolds of arylpyrrole or fipronil. The seven most promising compounds, selected based on their anthelmintic activity and/or limited cytotoxicity, are arylpyrroles that reduced the motility of fourth-stage larvae (L4s) with significant potency (IC values ranged from 0.04 ± 0.01 μM to 4.25 ± 0.82 μM, and selectivity indices ranged from 10.6 to 412.5). Since the parent structures of the active compounds are uncouplers of oxidative phosphorylation, we tested the effect of selected analogues on oxygen consumption in xL3s using the Seahorse XF24 flux analyser. Larvae treated with the test compounds showed a significant increase in oxygen consumption compared with the untreated control, demonstrating their uncoupling activity. Overall, the results of the present study have identified natural product-derived molecules that are worth considering for chemical optimisation as anthelmintic drug leads.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijpddr.2018.06.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6083343PMC
December 2018

APP deficiency results in resistance to obesity but impairs glucose tolerance upon high fat feeding.

J Endocrinol 2018 06 19;237(3):311-322. Epub 2018 Apr 19.

Metabolic Research UnitSchool of Medicine and Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria, Australia

The amyloid precursor protein (APP) generates a number of peptides when processed through different cleavage mechanisms, including the amyloid beta peptide that is implicated in the development of Alzheimer's disease. It is well established that APP via its cleaved peptides regulates aspects of neuronal metabolism. Emerging evidence suggests that amyloidogenic processing of APP can lead to altered systemic metabolism, similar to that observed in metabolic disease states. In the present study, we investigated the effect of APP deficiency on obesity-induced alterations in systemic metabolism. Compared with WT littermates, APP-deficient mice were resistant to diet-induced obesity, which was linked to higher energy expenditure and lipid oxidation throughout the dark phase and was associated with increased spontaneous physical activity. Consistent with this lean phenotype, APP-deficient mice fed a high-fat diet (HFD) had normal insulin tolerance. However, despite normal insulin action, these mice were glucose intolerant, similar to WT mice fed a HFD. This was associated with reduced plasma insulin in the early phase of the glucose tolerance test. Analysis of the pancreas showed that APP was required to maintain normal islet and β-cell mass under high fat feeding conditions. These studies show that, in addition to regulating aspects of neuronal metabolism, APP is an important regulator of whole body energy expenditure and glucose homeostasis under high fat feeding conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1530/JOE-18-0051DOI Listing
June 2018

Bioenergetics and synaptic plasticity as potential targets for individualizing treatment for depression.

Neurosci Biobehav Rev 2018 07 12;90:212-220. Epub 2018 Apr 12.

Department of Psychiatry and Psychology, Mayo Clinic Depression Center, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, United States; Deakin University, School of Medicine, 75 Pigdons Road, Waurn Ponds, VIC 3216, Australia; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States; Deakin University, School of Psychology, 221 Burwood Highway, Burwood, VIC 3154, Australia; Queensland Brain Institute, The Universty of Queensland, St Lucia, QLD 4072, Australia. Electronic address:

Disruptions of bioenergetic signaling and neurogenesis are hallmarks of depression physiology and are often the product of dysregulation of the inflammatory, stress-response, and metabolic systems. These systems are extensively interrelated at the physiological level, yet the bulk of the literature to date addresses pathophysiological mechanisms in isolation. A more integrated understanding of the etiology, progression, and treatment response profiles of depression is possible through wider consideration of relevant preclinical and clinical studies that examine the result of disruptions in these systems. Here, we review recent data demonstrating the critical effects of bioenergetic disruption on neuroplasticity and the development and progression of depressive illness. We further highlight the interactive and dynamic nature of the inflammatory and stress response systems and how disruption of these systems influences bioenergetic signaling pathways critical to treatment outcomes. In so doing, we underscore the pressing need to reconsider the implications of treatment resistance and present a framework for developing novel, personalized treatment approaches for depression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neubiorev.2018.04.002DOI Listing
July 2018

Metabolic reprogramming in type 2 diabetes and the development of breast cancer.

J Endocrinol 2018 05 27;237(2):R35-R46. Epub 2018 Feb 27.

Metabolic Reprogramming LaboratoryMetabolic Research Unit, School of Medicine and Centre for Molecular and Medical Research, Deakin University, Geelong, Australia

A wealth of epidemiological data has found that patients with type 2 diabetes have a greater risk of developing breast cancer. The molecular mechanisms underpinning this relationship are yet to be elucidated; however, this review examines the available evidence suggesting that the metabolic abnormalities observed in type 2 diabetes can predispose to the development of breast cancer. Alterations in substrate availability and the hormonal milieu, particularly hyperinsulinemia, not only create a favorable metabolic environment for tumorigenesis, but also induce metabolic reprogramming events that are required for the transformation of breast cancer cells. In addition, the dysfunction and hypoxia of adipose tissue surrounding the breast cancer niche is another putative link that will be discussed. Finally, the mechanisms by which breast cancer cells evade checkpoints associated with nutrient overload will be examined. Experimentally validating these potential links will be important for prediction and treatment of breast cancer in patients with type 2 diabetes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1530/JOE-18-0037DOI Listing
May 2018

Mechanisms Underpinning the Polypharmacy Effects of Medications in Psychiatry.

Int J Neuropsychopharmacol 2018 06;21(6):582-591

Centre for Molecular and Medical Research, School of Medicine, Deakin University, Geelong, VIC, Australia.

Background: Bipolar disorder is a mental health condition with progressive social and cognitive function disturbances. Most patients' treatments are based on polypharmacy, but with no biological basis and little is known of the drugs' interactions. The aim of this study was to analyze the effects of lithium, valproate, quetiapine, and lamotrigine, and the interactions between them, on markers of inflammation, bioenergetics, mitochondrial function, and oxidative stress in neuron-like cells and microglial cells.

Methods: Neuron-like cells and lipopolysaccharide-stimulated C8-B4 cells were treated with lithium (2.5 mM), valproate (0.5 mM), quetiapine (0.05 mM), and lamotrigine (0.05 mM) individually and in all possible combinations for 24 h. Twenty cytokines were measured in the media from lipopolysaccharide-stimulated C8-B4 cells. Metabolic flux analysis was used to measure bioenergetics, and real-time PCR was used to measure the expression of mitochondrial function genes in neuron-like cells. The production of superoxide in treated cells was also assessed.

Results: The results suggest major inhibitory effects on proinflammatory cytokine release as a therapeutic mechanism of these medications when used in combination. The various combinations of medications also caused overexpression of PGC1α and ATP5A1 in neuron-like cells. Quetiapine appears to have a proinflammatory effect in microglial cells, but this was reversed by the addition of lamotrigine independent of the drug combination.

Conclusion: Polypharmacy in bipolar disorder may have antiinflammatory effects on microglial cells as well as effects on mitochondrial biogenesis in neuronal cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/ijnp/pyy014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6007392PMC
June 2018

Loss of BIM increases mitochondrial oxygen consumption and lipid oxidation, reduces adiposity and improves insulin sensitivity in mice.

Cell Death Differ 2018 01 20;25(1):217-225. Epub 2017 Oct 20.

St. Vincent's Institute, Fitzroy, VIC 3065, Australia.

BCL-2 proteins are known to engage each other to determine the fate of a cell after a death stimulus. However, their evolutionary conservation and the many other reported binding partners suggest an additional function not directly linked to apoptosis regulation. To identify such a function, we studied mice lacking the BH3-only protein BIM. BIM cells had a higher mitochondrial oxygen consumption rate that was associated with higher mitochondrial complex IV activity. The consequences of increased oxygen consumption in BIM mice were significantly lower body weights, reduced adiposity and lower hepatic lipid content. Consistent with reduced adiposity, BIM mice had lower fasting blood glucose, improved insulin sensitivity and hepatic insulin signalling. Lipid oxidation was increased in BIM mice, suggesting a mechanism for their metabolic phenotype. Our data suggest a role for BIM in regulating mitochondrial bioenergetics and metabolism and support the idea that regulation of metabolism and cell death are connected.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/cdd.2017.168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729528PMC
January 2018

Deguelin exerts potent nematocidal activity the mitochondrial respiratory chain.

FASEB J 2017 10 7;31(10):4515-4532. Epub 2017 Jul 7.

Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia;

As a result of limited classes of anthelmintics and an over-reliance on chemical control, there is a great need to discover new compounds to combat drug resistance in parasitic nematodes. Here, we show that deguelin, a plant-derived rotenoid, selectively and potently inhibits the motility and development of nematodes, which supports its potential as a lead candidate for drug development. Furthermore, we demonstrate that deguelin treatment significantly increases gene transcription that is associated with energy metabolism, particularly oxidative phosphorylation and mitoribosomal protein production before inhibiting motility. Mitochondrial tracking confirmed enhanced oxidative phosphorylation. In accordance, real-time measurements of oxidative phosphorylation in response to deguelin treatment demonstrated an immediate decrease in oxygen consumption in both parasitic () and free-living () nematodes. Consequently, we hypothesize that deguelin is exerting its toxic effect on nematodes as a modulator of oxidative phosphorylation. This study highlights the dynamic biologic response of multicellular organisms to deguelin perturbation.-Preston, S., Korhonen, P. K., Mouchiroud, L., Cornaglia, M., McGee, S. L., Young, N. D., Davis, R. A., Crawford, S., Nowell, C., Ansell, B. R. E., Fisher, G. M., Andrews, K. T., Chang, B. C. H., Gijs, M. A. M., Sternberg, P. W., Auwerx, J., Baell, J., Hofmann, A., Jabbar, A., Gasser, R. B. Deguelin exerts potent nematocidal activity the mitochondrial respiratory chain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.201700288RDOI Listing
October 2017
-->