ORCID Profile
0000-0001-5975-0971
Current Organisation
Charles Perkins Centre
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Publisher: American Physiological Society
Date: 15-05-2015
DOI: 10.1152/AJPENDO.00289.2014
Abstract: The adaptive response of skeletal muscle to exercise training is tightly controlled and therefore requires transcriptional regulation. DNA methylation is an epigenetic mechanism known to modulate gene expression, but its contribution to exercise-induced adaptations in skeletal muscle is not well studied. Here, we describe a genome-wide analysis of DNA methylation in muscle of trained mice ( n = 3). Compared with sedentary controls, 2,762 genes exhibited differentially methylated CpGs ( P 0.05, meth diff %, coverage ) in their putative promoter regions. Alignment with gene expression data ( n = 6) revealed 200 genes with a negative correlation between methylation and expression changes in response to exercise training. The majority of these genes were related to muscle growth and differentiation, and a minor fraction involved in metabolic regulation. Among the candidates were genes that regulate the expression of myogenic regulatory factors ( Plexin A2) as well as genes that participate in muscle hypertrophy ( Igfbp4) and motor neuron innervation ( Dok7). Interestingly, a transcription factor binding site enrichment study discovered significantly enriched occurrence of CpG methylation in the binding sites of the myogenic regulatory factors MyoD and myogenin. These findings suggest that DNA methylation is involved in the regulation of muscle adaptation to regular exercise training.
Publisher: Frontiers Media SA
Date: 30-09-2020
Publisher: Elsevier BV
Date: 10-2020
Publisher: Wiley
Date: 11-11-2010
Abstract: Self-reactive B lymphocytes contribute to type 1 diabetes pathogenesis as APC and auto-Ab producers in NOD mice and humans. To shed light on the mechanisms responsible for the breakdown in B-lymphocyte self-tolerance to β-cell Ag, we utilised a model whereby hen-egg lysozyme (HEL)-specific Ig Tg (IgHEL-Tg)-Tg B lymphocytes were allowed to develop in or were transferred into mice expressing the HEL Tg under an insulin promoter (insHEL-Tg). IgHEL-Tg B lymphocytes enhanced type 1 diabetes susceptibility of insHEL-Tg NOD mice. A comparison of the tolerogenic activity of IgHEL-Tg B lymphocytes with NOD and non-autoimmune-prone C57BL/6 genetic backgrounds showed that both were rendered anergic in the presence of insHEL when competing with polyclonal B lymphocytes. Nevertheless, NOD IgHEL-Tg B lymphocytes transferred into insHEL-Tg mice were more readily susceptible to rescue from anergy than their C57BL/6 counterparts, following provision of in vivo T-cell help. The different tolerogenic outcomes were an intrinsic property of B lymphocytes rather than being related to the quality of T-cell help, with the defective response being at least partially controlled by genes mapping to insulin-dependent diabetes (Idd) susceptibility loci on Chromosome 1 (Idd5) and 4 (Idd9/11).
Publisher: Public Library of Science (PLoS)
Date: 13-07-2012
Publisher: Springer Science and Business Media LLC
Date: 20-02-2013
DOI: 10.1007/S00125-013-2846-8
Abstract: Metabolic disorders are commonly investigated using knockout and transgenic mouse models. A variety of mouse strains have been used for this purpose. However, mouse strains can differ in their inherent propensities to develop metabolic disease, which may affect the experimental outcomes of metabolic studies. We have investigated strain-dependent differences in the susceptibility to diet-induced obesity and insulin resistance in five commonly used inbred mouse strains (C57BL/6J, 129X1/SvJ, BALB/c, DBA/2 and FVB/N). Mice were fed either a low-fat or a high-fat diet (HFD) for 8 weeks. Whole-body energy expenditure and body composition were then determined. Tissues were used to measure markers of mitochondrial metabolism, inflammation, oxidative stress and lipid accumulation. BL6, 129X1, DBA/2 and FVB/N mice were all susceptible to varying degrees to HFD-induced obesity, glucose intolerance and insulin resistance, but BALB/c mice exhibited some protection from these detrimental effects. This protection could not be explained by differences in mitochondrial metabolism or oxidative stress in liver or muscle, or inflammation in adipose tissue. Interestingly, in contrast with the other strains, BALB/c mice did not accumulate excess lipid (triacylglycerols and diacylglycerols) in the liver this is potentially related to lower fatty acid uptake rather than differences in lipogenesis or lipid oxidation. Collectively, our findings indicate that most mouse strains develop metabolic defects on an HFD. However, there are inherent differences between strains, and thus the genetic background needs to be considered carefully in metabolic studies.
Publisher: American Physiological Society
Date: 15-12-2015
DOI: 10.1152/AJPENDO.00338.2015
Abstract: In humans and rodents, risk of metabolic syndrome is sexually dimorphic, with an increased incidence in males. Additionally, the protective role of female gonadal hormones is ostensible, as prevalence of type 2 diabetes mellitus (T2DM) increases after menopause. Here, we investigated the influence of estrogen (E 2 ) on the onset of T2DM in female New Zealand obese (NZO) mice. Diabetes prevalence (defined as blood glucose levels .6 mmol/l) of NZO females on high-fat diet (60 kcal% fat) in week 22 was 43%. This was markedly dependent on liver fat content in week 10, as detected by computed tomography. Only mice with a liver fat content % in week 10 plus glucose levels mmol/l in week 9 developed hyperglycemia by week 22. In addition, at 11 wk, diacylglycerols were elevated in livers of diabetes-prone mice compared with controls. Hepatic expression profiles obtained from diabetes-prone and -resistant mice at 11 wk revealed increased abundance of two transcripts in diabetes-prone mice: Mogat1, which catalyzes the synthesis of diacylglycerols from monoacylglycerol and fatty acyl-CoA, and the fatty acid transporter Cd36. E 2 treatment of diabetes-prone mice for 10 wk prevented any further increase in liver fat content and reduced diacylglycerols and the abundance of Mogat1 and Cd36, leading to a reduction of diabetes prevalence and an improved glucose tolerance compared with untreated mice. Our data indicate that early elevation of hepatic Cd36 and Mogat1 associates with increased production and accumulation of triglycerides and diacylglycerols, presumably resulting in reduced hepatic insulin sensitivity and leading to later onset of T2DM.
Publisher: Springer Science and Business Media LLC
Date: 06-2012
No related grants have been discovered for Nicole Hallahan.