Hayley O'Neill - Academia.edu (original) (raw)
Papers by Hayley O'Neill
The FASEB Journal, 2014
OBJECTIVE: To investigates the metabolic effects of leukemia inhibitory factor (LIF) in mouse ske... more OBJECTIVE: To investigates the metabolic effects of leukemia inhibitory factor (LIF) in mouse skeletal muscle. METHODS: Effects of LIF on muscle glucose transport, palmitate oxidation and cellular signaling were investigated in soleus and extensor digitorum longus (EDL) muscles from chow and highfat diet fed wildtype (WT) mice or chow fed muscle-specific AMPKα2 kinase-dead (KD) and suppressors of cytokine signaling (SOCS) 3 muscle-specific knockout mice. RESULTS: LIF increased muscle glucose transport in a dose- and time-dependent manner. LIF increased Akt Ser473-P, whereas AMPK Thr172-P was unaffected. Incubation of muscles from KD or WT mice with Wortmannin, LY294002 and Parthenolide demonstrated that PI3-kinase, but not AMPK, was essential for LIF-stimulated glucose transport. Incubation with Rapamycin and AZD8055 demonstrated that mammalian target of rapamycin complex (mTORC)2 and not mTORC1 is necessary for LIF-stimulated glucose transport. LIF-stimulated glucose transport was maintained in EDL muscl...
Exercise and physical activity are important components in both the management and treatment of t... more Exercise and physical activity are important components in both the management and treatment of type 2 diabetes. Exercise promotes multiple beneficial effects for diabetics; however, some studies have shown that when some individuals undergo an exercise program, this can cause behavioural compensatory responses. Therefore, we investigated whether an aerobic exercise program influences sedentary behavior (SB) and moderate-vigorous physical activity (MVPA) in type 2 diabetics. Eight volunteers (51.1±8.2 years; 4 men) underwent an exercise program (3 d.wk-1, 50– 60% of VO2 peak, 30–60 min) for 8 weeks. SB and MVPA were measured by triaxial accelerometers preand post-exercise intervention. Cardiorespiratory fitness, anthropometric assessment and body composition were measured at baseline and post-exercise intervention. Statistical analyses were performed using parametric tests (Paired t-test, p<0.05). We found there was no difference in SB and MVPA in type 2 diabetics, although there...
Obesity Research & Clinical Practice, 2019
Nutrients, 2019
Although the oral microbiota is known to play a crucial role in human health, there are few studi... more Although the oral microbiota is known to play a crucial role in human health, there are few studies of diet x oral microbiota interactions, and none in elite athletes who may manipulate their intakes of macronutrients to achieve different metabolic adaptations in pursuit of optimal endurance performance. The aim of this study was to investigate the shifts in the oral microbiome of elite male endurance race walkers from Europe, Asia, the Americas and Australia, in response to one of three dietary patterns often used by athletes during a period of intensified training: a High Carbohydrate (HCHO; n = 9; with 60% energy intake from carbohydrates; ~8.5 g kg−1 day−1 carbohydrate, ~2.1 g kg−1 day−1 protein, 1.2 g kg−1 day−1 fat) diet, a Periodised Carbohydrate (PCHO; n = 10; same macronutrient composition as HCHO, but the intake of carbohydrates is different across the day and throughout the week to support training sessions with high or low carbohydrate availability) diet or a ketogenic L...
Nutrients, 2019
We investigated extreme changes in diet patterns on the gut microbiota of elite race walkers unde... more We investigated extreme changes in diet patterns on the gut microbiota of elite race walkers undertaking intensified training and its possible links with athlete performance. Numerous studies with sedentary subjects have shown that diet and/or exercise can exert strong selective pressures on the gut microbiota. Similar studies with elite athletes are relatively scant, despite the recognition that diet is an important contributor to sports performance. In this study, stool samples were collected from the cohort at the beginning (baseline; BL) and end (post-treatment; PT) of a three-week intensified training program during which athletes were assigned to a High Carbohydrate (HCHO), Periodised Carbohydrate (PCHO) or ketogenic Low Carbohydrate High Fat (LCHF) diet (post treatment). Microbial community profiles were determined by 16S rRNA gene amplicon sequencing. The microbiota profiles at BL could be separated into distinct “enterotypes,” with either a Prevotella or Bacteroides dominat...
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, Jul 22, 2016
Adipose tissue expansion occurs through a combination of hypertrophy of existing adipocytes and g... more Adipose tissue expansion occurs through a combination of hypertrophy of existing adipocytes and generation of new adipocytesviathe process of hyperplasia, which involves the proliferation and subsequent differentiation of preadipocytes. Deficiencies in hyperplasia contribute to adipose tissue dysfunction and the association of obesity with chronic cardiometabolic diseases. Thus, increased understanding of hyperplastic pathways may be expected to afford novel therapeutic strategies. We have reported that fibroblast growth factor (FGF)-1 promotes proliferation and differentiation of human preadipocytes and recently demonstrated that bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) is a central, proximal effector. Herein, we describe the identification and characterization of carboxypeptidase X (CPX)-1, a secreted collagen-binding glycoprotein, as a novel downstream effector in human primary and Simpson-Golabi-Behmel syndrome preadipocytes. CPX-1 expression incre...
Biochemical and Biophysical Research Communications, 2015
Carboxypeptidase X-1 (CPX-1) is an atypical member of the carboxypeptidase (CP) family of protein... more Carboxypeptidase X-1 (CPX-1) is an atypical member of the carboxypeptidase (CP) family of proteins involved in a variety of physiological and pathological processes. However, unlike most other family members CPX-1 lacks catalytic activity making its biological function unclear. CPX-1 contains a 160 amino acid discoidin domain (DSD) that serves as a binding domain in other proteins prompting us to investigate a putative functional role for this domain in CPX-1. Sequence alignment confirmed the overarching homology between the DSD of CPX-1 and other DSDs whilst more detailed analysis revealed conservation of the residues known to form the collagen-binding trench within the DSD of the discoidin domain receptors (DDRs) 1 and 2. Biochemical characterisation of transiently expressed human CPX-1 revealed that CPX-1 was secreted in an N-glycosylation-dependent manner as treatment with the N-glycosylation inhibitor tunicamycin inhibited secretion concomitant with a reduction in CPX-1 mobility on Western blot. Using a collagen pull-down assay we found that secreted CPX-1 bound collagen and this appeared independent of N-glycosylation as treatment with PNGaseF did not affect binding. Further analysis under non-reducing and reducing (+DTT) conditions revealed that CPX-1 was secreted in both monomeric and dimeric forms and only the former bound collagen. Finally, mutation of a key residue situated within the putative collagen-binding trench within the DSD of CPX-1 (R192A) significantly reduced secretion and collagen-binding by 40% and 60%, respectively. Collectively these results demonstrate that CPX-1 is a secreted collagen-binding glycoprotein and provide a foundation for future studies investigating the function of CPX-1.
Diabetes & Metabolism Journal, 2013
Physiological reports, 2015
During submaximal exercise fatty acids are a predominant energy source for muscle contractions. A... more During submaximal exercise fatty acids are a predominant energy source for muscle contractions. An important regulator of fatty acid oxidation is acetyl-CoA carboxylase (ACC), which exists as two isoforms (ACC1 and ACC2) with ACC2 predominating in skeletal muscle. Both ACC isoforms regulate malonyl-CoA production, an allosteric inhibitor of carnitine palmitoyltransferase 1 (CPT-1); the primary enzyme controlling fatty acyl-CoA flux into mitochondria for oxidation. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is activated during exercise or by pharmacological agents such as metformin and AICAR. In resting muscle the activation of AMPK with AICAR leads to increased phosphorylation of ACC (S79 on ACC1 and S221 on ACC2), which reduces ACC activity and malonyl-CoA; effects associated with increased fatty acid oxidation. However, whether this pathway is vital for regulating skeletal muscle fatty acid oxidation during conditions of increased metabolic flux...
American journal of physiology. Endocrinology and metabolism, Jan 12, 2015
Members of the interleukin-6 (IL-6) family, IL-6 and ciliary neurotrophic factor (CNTF) have been... more Members of the interleukin-6 (IL-6) family, IL-6 and ciliary neurotrophic factor (CNTF) have been shown to increase glucose uptake and fatty acid oxidation in skeletal muscle. However, the metabolic effects of another family member, leukemia inhibitory factor (LIF), are not well characterized. Effects of LIF on skeletal muscle glucose uptake, palmitate oxidation and signaling were investigated in ex-vivo incubated mouse soleus and EDL muscles from muscle-specific AMPKα2 kinase-dead, muscle-specific SOCS3 knockout, and lean and high-fat fed mice. Inhibitors were used to investigate involvement of specific signaling pathways. LIF increased muscle glucose uptake in dose (50-5000 pM/L) and time-dependent manners with maximal effects at the 30 min time-point. LIF increased Akt Ser473-P in soleus and EDL, whereas AMPK Thr172-P was unaffected. Incubation with Parthenolide abolished LIF-induced glucose uptake and STAT3 Tyr705-P, whereas, incubation with LY-294002 and Wortmannin suppressed b...
Obesity Research & Clinical Practice, 2014
Background: Engaging patients in a group-based weight loss program is a challenge for the acuteca... more Background: Engaging patients in a group-based weight loss program is a challenge for the acutecare hospital outpatient setting. Aim: To evaluate a telephone-based weight loss service as an alternative to an existing faceto-face, group-based service in terms of reach, effectiveness and cost-effectiveness. Methods: Two-group pre-post design feasibility study. Patients who declined a 2-month groupbased program were offered a 6-month telephone program. Outcomes (primary effectiveness outcome = objectively measured weight) were assessed at baseline, 2-months, and 6-months (telephone only). Changes within the telephone program were analysed by paired t-tests. Differences between the programs at 2-months were compared with linear regression models, adjusting for baseline values and confounders. The cost per healthy life year gained was calculated for both programs. Results: Fifty patients (19% of referrals) commenced the group-based program (60% female, 57.4 ± 13.5 years [mean ± SD]), with 66% completion at 2-months. Sixty-one patients (44% of eligible) commenced the telephone program (46% female; 49.3 ± 12.0 years), with 57% completion at 6-months. The telephone program achieved significant weight loss (−4.1 ± 5.0% body weight, p < 0.05) at 6-months. Compared to the group-based program, the telephone program was associated with greater weight loss (mean difference [95%CI]: −2.0 [−3.4,−0.6] % body weight change; p = 0.007) at 2
EMBO molecular medicine, Mar 9, 2015
Pattern recognition receptors link metabolite and bacteria-derived inflammation to insulin resist... more Pattern recognition receptors link metabolite and bacteria-derived inflammation to insulin resistance during obesity. We demonstrate that NOD2 detection of bacterial cell wall peptidoglycan (PGN) regulates metabolic inflammation and insulin sensitivity. An obesity-promoting high-fat diet (HFD) increased NOD2 in hepatocytes and adipocytes, and NOD2(-/-) mice have increased adipose tissue and liver inflammation and exacerbated insulin resistance during a HFD. This effect is independent of altered adiposity or NOD2 in hematopoietic-derived immune cells. Instead, increased metabolic inflammation and insulin resistance in NOD2(-/-) mice is associated with increased commensal bacterial translocation from the gut into adipose tissue and liver. An intact PGN-NOD2 sensing system regulated gut mucosal bacterial colonization and a metabolic tissue dysbiosis that is a potential trigger for increased metabolic inflammation and insulin resistance. Gut dysbiosis in HFD-fed NOD2(-/-) mice is an ind...
Physiological Reports, 2014
PloS one, 2013
Diet-induced obesity is a rising health concern which can lead to the development of glucose into... more Diet-induced obesity is a rising health concern which can lead to the development of glucose intolerance and muscle insulin resistance and, ultimately, type II diabetes mellitus. This research investigates the associations between glucose intolerance or muscle insulin resistance and tissue specific changes during the progression of diet-induced obesity. C57BL/6J mice were fed a normal or high-fat diet (HFD; 60% kcal fat) for 3 or 8 weeks. Disease progression was monitored by measurements of body/tissue mass changes, glucose and insulin tolerance tests, and ex vivo glucose uptake in intact muscles. Lipid metabolism was analyzed using metabolic chambers and ex vivo palmitate assays in intact muscles. Skeletal muscle, liver and adipose tissues were analyzed for changes in inflammatory gene expression. Plasma was analyzed for insulin levels and inflammatory proteins. Histological techniques were used on muscle and liver cryosections to assess metabolic and morphological changes. A rapid...
The FASEB Journal, 2014
AMP-activated protein kinase (AMPK) is a master regulator of metabolism. While muscle-specific AM... more AMP-activated protein kinase (AMPK) is a master regulator of metabolism. While muscle-specific AMPK β1β2 double-knockout (β1β2M-KO) mice display alterations in metabolic and mitochondrial capacity, their severe exercise intolerance suggested a secondary contributor to the observed phenotype. We find that tibialis anterior (TA), but not soleus, muscles of sedentary β1β2M-KO mice display a significant myopathy (decreased myofiber areas, increased split and necrotic myofibers, and increased centrally nucleated myofibers. A mitochondrial- and fiber-type-specific etiology to the myopathy was ruled out. However, β1β2M-KO TA muscles displayed significant (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) increases in platelet aggregation and apoptosis within myofibers and surrounding interstitium (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). These changes correlated with a 45% decrease in capillary density…
Proceedings of the National Academy of Sciences, 2011
AMP-activated protein kinase (AMPK) β1 or β2 subunits are required for assembling of AMPK heterot... more AMP-activated protein kinase (AMPK) β1 or β2 subunits are required for assembling of AMPK heterotrimers and are important for regulating enzyme activity and cellular localization. In skeletal muscle, α2β2γ3-containing heterotrimers predominate. However, compensatory up-regulation and redundancy of AMPK subunits in whole-body AMPK α2, β2, and γ3 null mice has made it difficult to determine the physiological importance of AMPK in regulating muscle metabolism, because these models have normal mitochondrial content, contraction-stimulated glucose uptake, and insulin sensitivity. In the current study, we generated mice lacking both AMPK β1 and β2 isoforms in skeletal muscle (β1β2M-KO). β1β2M-KO mice are physically inactive and have a drastically impaired capacity for treadmill running that is associated with reductions in skeletal muscle mitochondrial content but not a fiber-type switch. Interestingly, young β1β2M-KO mice fed a control chow diet are not obese or insulin resistant but do ...
Obesity Research & Clinical Practice, 2013
Molecular and Cellular Endocrinology, 2013
Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a... more Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a major site for glucose and lipid oxidation. Obesity and type 2 diabetes are causally linked through their association with skeletal muscle insulin resistance, while conversely exercise is known to improve whole body glucose homeostasis simultaneously with muscle insulin sensitivity. Exercise activates skeletal muscle AMP-activated protein kinase (AMPK). AMPK plays a role in regulating exercise capacity, skeletal muscle mitochondrial content and contraction-stimulated glucose uptake. Skeletal muscle AMPK is also thought to be important for regulating fatty acid metabolism; however, direct genetic evidence in this area is currently lacking. This review will discuss the current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise, and highlight the potential implications in the development of insulin resistance.
The FASEB Journal, 2014
OBJECTIVE: To investigates the metabolic effects of leukemia inhibitory factor (LIF) in mouse ske... more OBJECTIVE: To investigates the metabolic effects of leukemia inhibitory factor (LIF) in mouse skeletal muscle. METHODS: Effects of LIF on muscle glucose transport, palmitate oxidation and cellular signaling were investigated in soleus and extensor digitorum longus (EDL) muscles from chow and highfat diet fed wildtype (WT) mice or chow fed muscle-specific AMPKα2 kinase-dead (KD) and suppressors of cytokine signaling (SOCS) 3 muscle-specific knockout mice. RESULTS: LIF increased muscle glucose transport in a dose- and time-dependent manner. LIF increased Akt Ser473-P, whereas AMPK Thr172-P was unaffected. Incubation of muscles from KD or WT mice with Wortmannin, LY294002 and Parthenolide demonstrated that PI3-kinase, but not AMPK, was essential for LIF-stimulated glucose transport. Incubation with Rapamycin and AZD8055 demonstrated that mammalian target of rapamycin complex (mTORC)2 and not mTORC1 is necessary for LIF-stimulated glucose transport. LIF-stimulated glucose transport was maintained in EDL muscl...
Exercise and physical activity are important components in both the management and treatment of t... more Exercise and physical activity are important components in both the management and treatment of type 2 diabetes. Exercise promotes multiple beneficial effects for diabetics; however, some studies have shown that when some individuals undergo an exercise program, this can cause behavioural compensatory responses. Therefore, we investigated whether an aerobic exercise program influences sedentary behavior (SB) and moderate-vigorous physical activity (MVPA) in type 2 diabetics. Eight volunteers (51.1±8.2 years; 4 men) underwent an exercise program (3 d.wk-1, 50– 60% of VO2 peak, 30–60 min) for 8 weeks. SB and MVPA were measured by triaxial accelerometers preand post-exercise intervention. Cardiorespiratory fitness, anthropometric assessment and body composition were measured at baseline and post-exercise intervention. Statistical analyses were performed using parametric tests (Paired t-test, p<0.05). We found there was no difference in SB and MVPA in type 2 diabetics, although there...
Obesity Research & Clinical Practice, 2019
Nutrients, 2019
Although the oral microbiota is known to play a crucial role in human health, there are few studi... more Although the oral microbiota is known to play a crucial role in human health, there are few studies of diet x oral microbiota interactions, and none in elite athletes who may manipulate their intakes of macronutrients to achieve different metabolic adaptations in pursuit of optimal endurance performance. The aim of this study was to investigate the shifts in the oral microbiome of elite male endurance race walkers from Europe, Asia, the Americas and Australia, in response to one of three dietary patterns often used by athletes during a period of intensified training: a High Carbohydrate (HCHO; n = 9; with 60% energy intake from carbohydrates; ~8.5 g kg−1 day−1 carbohydrate, ~2.1 g kg−1 day−1 protein, 1.2 g kg−1 day−1 fat) diet, a Periodised Carbohydrate (PCHO; n = 10; same macronutrient composition as HCHO, but the intake of carbohydrates is different across the day and throughout the week to support training sessions with high or low carbohydrate availability) diet or a ketogenic L...
Nutrients, 2019
We investigated extreme changes in diet patterns on the gut microbiota of elite race walkers unde... more We investigated extreme changes in diet patterns on the gut microbiota of elite race walkers undertaking intensified training and its possible links with athlete performance. Numerous studies with sedentary subjects have shown that diet and/or exercise can exert strong selective pressures on the gut microbiota. Similar studies with elite athletes are relatively scant, despite the recognition that diet is an important contributor to sports performance. In this study, stool samples were collected from the cohort at the beginning (baseline; BL) and end (post-treatment; PT) of a three-week intensified training program during which athletes were assigned to a High Carbohydrate (HCHO), Periodised Carbohydrate (PCHO) or ketogenic Low Carbohydrate High Fat (LCHF) diet (post treatment). Microbial community profiles were determined by 16S rRNA gene amplicon sequencing. The microbiota profiles at BL could be separated into distinct “enterotypes,” with either a Prevotella or Bacteroides dominat...
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, Jul 22, 2016
Adipose tissue expansion occurs through a combination of hypertrophy of existing adipocytes and g... more Adipose tissue expansion occurs through a combination of hypertrophy of existing adipocytes and generation of new adipocytesviathe process of hyperplasia, which involves the proliferation and subsequent differentiation of preadipocytes. Deficiencies in hyperplasia contribute to adipose tissue dysfunction and the association of obesity with chronic cardiometabolic diseases. Thus, increased understanding of hyperplastic pathways may be expected to afford novel therapeutic strategies. We have reported that fibroblast growth factor (FGF)-1 promotes proliferation and differentiation of human preadipocytes and recently demonstrated that bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) is a central, proximal effector. Herein, we describe the identification and characterization of carboxypeptidase X (CPX)-1, a secreted collagen-binding glycoprotein, as a novel downstream effector in human primary and Simpson-Golabi-Behmel syndrome preadipocytes. CPX-1 expression incre...
Biochemical and Biophysical Research Communications, 2015
Carboxypeptidase X-1 (CPX-1) is an atypical member of the carboxypeptidase (CP) family of protein... more Carboxypeptidase X-1 (CPX-1) is an atypical member of the carboxypeptidase (CP) family of proteins involved in a variety of physiological and pathological processes. However, unlike most other family members CPX-1 lacks catalytic activity making its biological function unclear. CPX-1 contains a 160 amino acid discoidin domain (DSD) that serves as a binding domain in other proteins prompting us to investigate a putative functional role for this domain in CPX-1. Sequence alignment confirmed the overarching homology between the DSD of CPX-1 and other DSDs whilst more detailed analysis revealed conservation of the residues known to form the collagen-binding trench within the DSD of the discoidin domain receptors (DDRs) 1 and 2. Biochemical characterisation of transiently expressed human CPX-1 revealed that CPX-1 was secreted in an N-glycosylation-dependent manner as treatment with the N-glycosylation inhibitor tunicamycin inhibited secretion concomitant with a reduction in CPX-1 mobility on Western blot. Using a collagen pull-down assay we found that secreted CPX-1 bound collagen and this appeared independent of N-glycosylation as treatment with PNGaseF did not affect binding. Further analysis under non-reducing and reducing (+DTT) conditions revealed that CPX-1 was secreted in both monomeric and dimeric forms and only the former bound collagen. Finally, mutation of a key residue situated within the putative collagen-binding trench within the DSD of CPX-1 (R192A) significantly reduced secretion and collagen-binding by 40% and 60%, respectively. Collectively these results demonstrate that CPX-1 is a secreted collagen-binding glycoprotein and provide a foundation for future studies investigating the function of CPX-1.
Diabetes & Metabolism Journal, 2013
Physiological reports, 2015
During submaximal exercise fatty acids are a predominant energy source for muscle contractions. A... more During submaximal exercise fatty acids are a predominant energy source for muscle contractions. An important regulator of fatty acid oxidation is acetyl-CoA carboxylase (ACC), which exists as two isoforms (ACC1 and ACC2) with ACC2 predominating in skeletal muscle. Both ACC isoforms regulate malonyl-CoA production, an allosteric inhibitor of carnitine palmitoyltransferase 1 (CPT-1); the primary enzyme controlling fatty acyl-CoA flux into mitochondria for oxidation. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is activated during exercise or by pharmacological agents such as metformin and AICAR. In resting muscle the activation of AMPK with AICAR leads to increased phosphorylation of ACC (S79 on ACC1 and S221 on ACC2), which reduces ACC activity and malonyl-CoA; effects associated with increased fatty acid oxidation. However, whether this pathway is vital for regulating skeletal muscle fatty acid oxidation during conditions of increased metabolic flux...
American journal of physiology. Endocrinology and metabolism, Jan 12, 2015
Members of the interleukin-6 (IL-6) family, IL-6 and ciliary neurotrophic factor (CNTF) have been... more Members of the interleukin-6 (IL-6) family, IL-6 and ciliary neurotrophic factor (CNTF) have been shown to increase glucose uptake and fatty acid oxidation in skeletal muscle. However, the metabolic effects of another family member, leukemia inhibitory factor (LIF), are not well characterized. Effects of LIF on skeletal muscle glucose uptake, palmitate oxidation and signaling were investigated in ex-vivo incubated mouse soleus and EDL muscles from muscle-specific AMPKα2 kinase-dead, muscle-specific SOCS3 knockout, and lean and high-fat fed mice. Inhibitors were used to investigate involvement of specific signaling pathways. LIF increased muscle glucose uptake in dose (50-5000 pM/L) and time-dependent manners with maximal effects at the 30 min time-point. LIF increased Akt Ser473-P in soleus and EDL, whereas AMPK Thr172-P was unaffected. Incubation with Parthenolide abolished LIF-induced glucose uptake and STAT3 Tyr705-P, whereas, incubation with LY-294002 and Wortmannin suppressed b...
Obesity Research & Clinical Practice, 2014
Background: Engaging patients in a group-based weight loss program is a challenge for the acuteca... more Background: Engaging patients in a group-based weight loss program is a challenge for the acutecare hospital outpatient setting. Aim: To evaluate a telephone-based weight loss service as an alternative to an existing faceto-face, group-based service in terms of reach, effectiveness and cost-effectiveness. Methods: Two-group pre-post design feasibility study. Patients who declined a 2-month groupbased program were offered a 6-month telephone program. Outcomes (primary effectiveness outcome = objectively measured weight) were assessed at baseline, 2-months, and 6-months (telephone only). Changes within the telephone program were analysed by paired t-tests. Differences between the programs at 2-months were compared with linear regression models, adjusting for baseline values and confounders. The cost per healthy life year gained was calculated for both programs. Results: Fifty patients (19% of referrals) commenced the group-based program (60% female, 57.4 ± 13.5 years [mean ± SD]), with 66% completion at 2-months. Sixty-one patients (44% of eligible) commenced the telephone program (46% female; 49.3 ± 12.0 years), with 57% completion at 6-months. The telephone program achieved significant weight loss (−4.1 ± 5.0% body weight, p < 0.05) at 6-months. Compared to the group-based program, the telephone program was associated with greater weight loss (mean difference [95%CI]: −2.0 [−3.4,−0.6] % body weight change; p = 0.007) at 2
EMBO molecular medicine, Mar 9, 2015
Pattern recognition receptors link metabolite and bacteria-derived inflammation to insulin resist... more Pattern recognition receptors link metabolite and bacteria-derived inflammation to insulin resistance during obesity. We demonstrate that NOD2 detection of bacterial cell wall peptidoglycan (PGN) regulates metabolic inflammation and insulin sensitivity. An obesity-promoting high-fat diet (HFD) increased NOD2 in hepatocytes and adipocytes, and NOD2(-/-) mice have increased adipose tissue and liver inflammation and exacerbated insulin resistance during a HFD. This effect is independent of altered adiposity or NOD2 in hematopoietic-derived immune cells. Instead, increased metabolic inflammation and insulin resistance in NOD2(-/-) mice is associated with increased commensal bacterial translocation from the gut into adipose tissue and liver. An intact PGN-NOD2 sensing system regulated gut mucosal bacterial colonization and a metabolic tissue dysbiosis that is a potential trigger for increased metabolic inflammation and insulin resistance. Gut dysbiosis in HFD-fed NOD2(-/-) mice is an ind...
Physiological Reports, 2014
PloS one, 2013
Diet-induced obesity is a rising health concern which can lead to the development of glucose into... more Diet-induced obesity is a rising health concern which can lead to the development of glucose intolerance and muscle insulin resistance and, ultimately, type II diabetes mellitus. This research investigates the associations between glucose intolerance or muscle insulin resistance and tissue specific changes during the progression of diet-induced obesity. C57BL/6J mice were fed a normal or high-fat diet (HFD; 60% kcal fat) for 3 or 8 weeks. Disease progression was monitored by measurements of body/tissue mass changes, glucose and insulin tolerance tests, and ex vivo glucose uptake in intact muscles. Lipid metabolism was analyzed using metabolic chambers and ex vivo palmitate assays in intact muscles. Skeletal muscle, liver and adipose tissues were analyzed for changes in inflammatory gene expression. Plasma was analyzed for insulin levels and inflammatory proteins. Histological techniques were used on muscle and liver cryosections to assess metabolic and morphological changes. A rapid...
The FASEB Journal, 2014
AMP-activated protein kinase (AMPK) is a master regulator of metabolism. While muscle-specific AM... more AMP-activated protein kinase (AMPK) is a master regulator of metabolism. While muscle-specific AMPK β1β2 double-knockout (β1β2M-KO) mice display alterations in metabolic and mitochondrial capacity, their severe exercise intolerance suggested a secondary contributor to the observed phenotype. We find that tibialis anterior (TA), but not soleus, muscles of sedentary β1β2M-KO mice display a significant myopathy (decreased myofiber areas, increased split and necrotic myofibers, and increased centrally nucleated myofibers. A mitochondrial- and fiber-type-specific etiology to the myopathy was ruled out. However, β1β2M-KO TA muscles displayed significant (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) increases in platelet aggregation and apoptosis within myofibers and surrounding interstitium (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). These changes correlated with a 45% decrease in capillary density…
Proceedings of the National Academy of Sciences, 2011
AMP-activated protein kinase (AMPK) β1 or β2 subunits are required for assembling of AMPK heterot... more AMP-activated protein kinase (AMPK) β1 or β2 subunits are required for assembling of AMPK heterotrimers and are important for regulating enzyme activity and cellular localization. In skeletal muscle, α2β2γ3-containing heterotrimers predominate. However, compensatory up-regulation and redundancy of AMPK subunits in whole-body AMPK α2, β2, and γ3 null mice has made it difficult to determine the physiological importance of AMPK in regulating muscle metabolism, because these models have normal mitochondrial content, contraction-stimulated glucose uptake, and insulin sensitivity. In the current study, we generated mice lacking both AMPK β1 and β2 isoforms in skeletal muscle (β1β2M-KO). β1β2M-KO mice are physically inactive and have a drastically impaired capacity for treadmill running that is associated with reductions in skeletal muscle mitochondrial content but not a fiber-type switch. Interestingly, young β1β2M-KO mice fed a control chow diet are not obese or insulin resistant but do ...
Obesity Research & Clinical Practice, 2013
Molecular and Cellular Endocrinology, 2013
Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a... more Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a major site for glucose and lipid oxidation. Obesity and type 2 diabetes are causally linked through their association with skeletal muscle insulin resistance, while conversely exercise is known to improve whole body glucose homeostasis simultaneously with muscle insulin sensitivity. Exercise activates skeletal muscle AMP-activated protein kinase (AMPK). AMPK plays a role in regulating exercise capacity, skeletal muscle mitochondrial content and contraction-stimulated glucose uptake. Skeletal muscle AMPK is also thought to be important for regulating fatty acid metabolism; however, direct genetic evidence in this area is currently lacking. This review will discuss the current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise, and highlight the potential implications in the development of insulin resistance.