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Politis-Barber V, Petrick HL, Raajendiran A, DesOrmeaux GJ, Brunetta HS, dos Reis LM, Mori MA, Wright DC, Watt MJ, Holloway GP. Ckmt1 is Dispensable for Mitochondrial Bioenergetics Within White/Beige Adipose Tissue. Function (Oxf) 2022; 3:zqac037. [PMID: 37954502 PMCID: PMC10633789 DOI: 10.1093/function/zqac037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/14/2023] Open
Abstract
Within brown adipose tissue (BAT), the brain isoform of creatine kinase (CKB) has been proposed to regulate the regeneration of ADP and phosphocreatine in a futile creatine cycle (FCC) that stimulates energy expenditure. However, the presence of FCC, and the specific creatine kinase isoforms regulating this theoretical model within white adipose tissue (WAT), remains to be fully elucidated. In the present study, creatine did not stimulate respiration in cultured adipocytes, isolated mitochondria or mouse permeabilized WAT. Additionally, while creatine kinase ubiquitous-type, mitochondrial (CKMT1) mRNA and protein were detected in human WAT, shRNA-mediated reductions in Ckmt1 did not decrease submaximal respiration in cultured adipocytes, and ablation of CKMT1 in mice did not alter energy expenditure, mitochondrial responses to pharmacological β3-adrenergic activation (CL 316, 243) or exacerbate the detrimental metabolic effects of consuming a high-fat diet. Taken together, these findings solidify CKMT1 as dispensable in the regulation of energy expenditure, and unlike in BAT, they do not support the presence of FCC within WAT.
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Affiliation(s)
- Valerie Politis-Barber
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
| | - Heather L Petrick
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
| | - Arthe Raajendiran
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Genevieve J DesOrmeaux
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
| | - Henver S Brunetta
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
- Department of Biochemistry and Tissue Biology, University of Campinas, Campinas - SP 13083-970, Brazil
| | - Larissa M dos Reis
- Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas, Campinas - SP 13083-970, Brazil
| | - Marcelo A Mori
- Department of Biochemistry and Tissue Biology, University of Campinas, Campinas - SP 13083-970, Brazil
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
| | - Matthew J Watt
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
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Cohen JN, Kuikman MA, Politis-Barber V, Stairs BE, Coates AM, Millar PJ, Burr JF. Blood flow restriction and stimulated muscle contractions do not improve metabolic or vascular outcomes following glucose ingestion in young, active individuals. J Appl Physiol (1985) 2022; 133:75-86. [DOI: 10.1152/japplphysiol.00178.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glucose ingestion and absorption into the blood stream can challenge glycemic regulation and vascular endothelial function. Muscular contractions in exercise promote a return to homeostasis by increasing glucose uptake and blood flow. Similarly, muscle hypoxia supports glycemic regulation by increasing glucose oxidation. Blood flow restriction (BFR) induces muscle hypoxia during occlusion and reactive hyperemia upon release. Thus, in the absence of exercise, electric muscle stimulation (EMS) and BFR may offer circulatory and glucoregulatory improvements. In 13 healthy, active participants (27±3yr, 7 female) we tracked post-glucose (oral 100g) glycemic, cardiometabolic and vascular function measures over 120min following four interventions: 1) BFR, 2) EMS, 3) BFR+EMS or 4) Control. BFR was applied at 2min intervals for 30min (70% occlusion), EMS was continuous for 30min (maximum-tolerable intensity). Glycemic and insulinemic responses did not differ between interventions (partial η2=0.11-0.15, P=0.2); however, only BFR+EMS demonstrated cyclic effects on oxygen consumption, carbohydrate oxidation, muscle oxygenation, heart rate, and blood pressure (all P<0.01). Endothelial function was reduced 60min post-glucose ingestion across interventions and recovered by 120min (5.9±2.6% vs 8.4±2.7%; P<0.001). Estimated microvascular function was not meaningfully different. Leg blood flow increased during EMS and BFR+EMS (+656±519mL•min-1, +433±510mL•min-1; P<0.001); however, only remained elevated following BFR intervention 90min post-glucose (+94±94mL•min-1; P=0.02). Superimposition of EMS onto cyclic BFR did not preferentially improve post-glucose metabolic or vascular function amongst young, active participants. Cyclic BFR increased blood flow delivery 60min beyond intervention, and BFR+EMS selectively increased carbohydrate usage and reduced muscle oxygenation warranting future clinical assessments.
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Affiliation(s)
- Jeremy N. Cohen
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Megan A. Kuikman
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Valerie Politis-Barber
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Brienne E. Stairs
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Alexandra M. Coates
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Philip J. Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Jamie F. Burr
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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Handy RM, Politis-Barber V, Barbeau PA. Revisiting the limitation to V ̇ O 2 peak with ageing: is mitochondrial (dys)function the key? J Physiol 2021; 599:4017-4019. [PMID: 34269415 DOI: 10.1113/jp282018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Rachel M Handy
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Valerie Politis-Barber
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Pierre-Andre Barbeau
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Petrick HL, Foley KP, Zlitni S, Brunetta HS, Paglialunga S, Miotto PM, Politis-Barber V, O’Dwyer C, Philbrick DJ, Fullerton MD, Schertzer JD, Holloway GP. Adipose Tissue Inflammation Is Directly Linked to Obesity-Induced Insulin Resistance, while Gut Dysbiosis and Mitochondrial Dysfunction Are Not Required. Function (Oxf) 2020; 1:zqaa013. [PMID: 34278304 PMCID: PMC8276887 DOI: 10.1093/function/zqaa013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/17/2020] [Accepted: 08/21/2020] [Indexed: 01/06/2023]
Abstract
Obesity is associated with adipose tissue hypertrophy, systemic inflammation, mitochondrial dysfunction, and intestinal dysbiosis. Rodent models of high-fat diet (HFD)-feeding or genetic deletion of multifunctional proteins involved in immunity and metabolism are often used to probe the etiology of obesity; however, these models make it difficult to divorce the effects of obesity, diet composition, or immunity on endocrine regulation of blood glucose. We, therefore, investigated the importance of adipose inflammation, mitochondrial dysfunction, and gut dysbiosis for obesity-induced insulin resistance using a spontaneously obese mouse model. We examined metabolic changes in skeletal muscle, adipose tissue, liver, the intestinal microbiome, and whole-body glucose control in spontaneously hyperphagic C57Bl/6J mice compared to lean littermates. A separate subset of lean and obese mice was subject to 8 weeks of obesogenic HFD feeding, or to pair feeding of a standard rodent diet. Hyperphagia, obesity, adipose inflammation, and insulin resistance were present in obese mice despite consuming a standard rodent diet, and these effects were blunted with caloric restriction. However, hyperphagic obese mice had normal mitochondrial respiratory function in all tissues tested and no discernable intestinal dysbiosis relative to lean littermates. In contrast, feeding mice an obesogenic HFD altered the composition of the gut microbiome, impaired skeletal muscle mitochondrial bioenergetics, and promoted poor glucose control. These data show that adipose inflammation and redox stress occurred in all models of obesity, but gut dysbiosis and mitochondrial respiratory dysfunction are not always required for obesity-induced insulin resistance. Rather, changes in the intestinal microbiome and mitochondrial bioenergetics may reflect physiological consequences of HFD feeding.
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Affiliation(s)
- Heather L Petrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Kevin P Foley
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Soumaya Zlitni
- Departments of Genetics and Medicine, Stanford University, Stanford, 94305, CA, USA
| | - Henver S Brunetta
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada,Department of Physiological Sciences, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | - Sabina Paglialunga
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Valerie Politis-Barber
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Conor O’Dwyer
- Department of Biochemistry, Microbiology and Immunology, Centre for Inflammation, Infection and Immunity, Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, Canada
| | - Diana J Philbrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Morgan D Fullerton
- Department of Biochemistry, Microbiology and Immunology, Centre for Inflammation, Infection and Immunity, Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, Canada
| | - Jonathan D Schertzer
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada,Address correspondence to G.P.H. (e-mail: )
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Brunetta HS, Politis-Barber V, Petrick HL, Dennis KMJH, Kirsh AJ, Barbeau PA, Nunes EA, Holloway GP. Nitrate attenuates high fat diet-induced glucose intolerance in association with reduced epididymal adipose tissue inflammation and mitochondrial reactive oxygen species emission. J Physiol 2020; 598:3357-3371. [PMID: 32449521 DOI: 10.1113/jp279455] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 05/19/2020] [Indexed: 12/20/2023] Open
Abstract
KEY POINTS Dietary nitrate is a prominent therapeutic strategy to mitigate some metabolic deleterious effects related to obesity. Mitochondrial dysfunction is causally linked to adipose tissue inflammation and insulin resistance. Whole-body glucose tolerance is prevented by nitrate independent of body weight and energy expenditure. Dietary nitrate reduces epididymal adipose tissue inflammation and mitochondrial reactive oxygen species emission while preserving insulin signalling. Metabolic beneficial effects of nitrate consumption are associated with improvements in mitochondrial redox balance in hypertrophic adipose tissue. ABSTRACT Evidence has accumulated to indicate that dietary nitrate alters energy expenditure and the metabolic derangements associated with a high fat diet (HFD), but the mechanism(s) of action remain incompletely elucidated. Therefore, we aimed to determine if dietary nitrate (4 mm sodium nitrate via drinking water) could prevent HFD-mediated glucose intolerance in association with improved mitochondrial bioenergetics within both white (WAT) and brown (BAT) adipose tissue in mice. HFD feeding caused glucose intolerance (P < 0.05) and increased body weight. As a result of higher body weight, energy expenditure increased proportionally. HFD-fed mice displayed greater mitochondrial uncoupling and a twofold increase in uncoupling protein 1 content within BAT. Within epididymal white adipose tissue (eWAT), HFD increased cell size (i.e. hypertrophy), mitochondrial H2 O2 emission, oxidative stress, c-Jun N-terminal kinase phosphorylation and leucocyte infiltration, and induced insulin resistance. Remarkably, dietary nitrate consumption attenuated and/or mitigated all these responses, including rendering mitochondria more coupled within BAT, and normalizing mitochondrial H2 O2 emission and insulin-mediated Akt-Thr308 phosphorylation within eWAT. Intriguingly, the positive effects of dietary nitrate appear to be independent of eWAT mitochondrial respiratory capacity and content. Altogether, these data suggest that dietary nitrate attenuates the development of HFD-induced insulin resistance in association with attenuating WAT inflammation and redox balance, independent of changes in either WAT or BAT mitochondrial respiratory capacity/content.
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Affiliation(s)
- Henver S Brunetta
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- Department of Physiological Sciences, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | - Valerie Politis-Barber
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Heather L Petrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Kaitlyn M J H Dennis
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Aleah J Kirsh
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Pierre-Andre Barbeau
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Everson A Nunes
- Department of Physiological Sciences, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Politis-Barber V, Brunetta HS, Paglialunga S, Petrick HL, Holloway GP. Long-term, high-fat feeding exacerbates short-term increases in adipose mitochondrial reactive oxygen species, without impairing mitochondrial respiration. Am J Physiol Endocrinol Metab 2020; 319:E376-E387. [PMID: 32543945 PMCID: PMC7473917 DOI: 10.1152/ajpendo.00028.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
White adipose tissue (WAT) dysfunction in obesity is implicated in the onset of whole body insulin resistance. Alterations in mitochondrial bioenergetics, namely impaired mitochondrial respiration and increased mitochondrial reactive oxygen species (mtROS) production, have been suggested to contribute to this metabolic dysregulation. However, techniques investigating mitochondrial function are classically normalized to tissue weight, which may be confounding when considering obesity-related adipocyte hypertrophy. Furthermore, the effect of long-term high-fat diet (HFD) on mtROS in WAT has yet to be elucidated. Therefore, we sought to determine the HFD-mediated temporal changes in mitochondrial respiration and mtROS emission in WAT. C57BL/6N mice received low-fat diet or HFD for 1 or 8 wk and changes in inguinal WAT (iWAT) and epididymal WAT (eWAT) were assessed. While tissue weight-normalized mitochondrial respiration was reduced in iWAT following 8-wk HFD-feeding, this effect was mitigated when adipocyte cell size and/or number were considered. These data suggest HFD does not impair mitochondrial respiratory capacity per adipocyte within WAT. In support of this assertion, within eWAT compensatory increases in lipid-supported and maximal succinate-supported respiration occurred at 8 wk despite cell hypertrophy and increases in WAT inflammation. Although these data suggest impairments in mitochondrial respiration do not contribute to HFD-mediated WAT phenotype, lipid-supported mtROS emission increased following 1-wk HFD in eWAT, while both lipid and carbohydrate-supported mtROS were increased at 8 wk in both depots. Combined, these data establish that while HFD does not impair adipocyte mitochondrial respiratory capacity, increased mtROS is an enduring physiological occurrence within WAT in HFD-induced obesity.
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Affiliation(s)
| | - Henver S. Brunetta
- 1Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- 2Department of Physiological Sciences, Federal University of Santa Catarina, Florianopolis, Brazil
| | - Sabina Paglialunga
- 1Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Heather L. Petrick
- 1Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Graham P. Holloway
- 1Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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