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Cinato M, Andersson L, Miljanovic A, Laudette M, Kunduzova O, Borén J, Levin MC. Role of Perilipins in Oxidative Stress-Implications for Cardiovascular Disease. Antioxidants (Basel) 2024; 13:209. [PMID: 38397807 PMCID: PMC10886189 DOI: 10.3390/antiox13020209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/25/2024] Open
Abstract
Oxidative stress is the imbalance between the production of reactive oxygen species (ROS) and antioxidants in a cell. In the heart, oxidative stress may deteriorate calcium handling, cause arrhythmia, and enhance maladaptive cardiac remodeling by the induction of hypertrophic and apoptotic signaling pathways. Consequently, dysregulated ROS production and oxidative stress have been implicated in numerous cardiac diseases, including heart failure, cardiac ischemia-reperfusion injury, cardiac hypertrophy, and diabetic cardiomyopathy. Lipid droplets (LDs) are conserved intracellular organelles that enable the safe and stable storage of neutral lipids within the cytosol. LDs are coated with proteins, perilipins (Plins) being one of the most abundant. In this review, we will discuss the interplay between oxidative stress and Plins. Indeed, LDs and Plins are increasingly being recognized for playing a critical role beyond energy metabolism and lipid handling. Numerous reports suggest that an essential purpose of LD biogenesis is to alleviate cellular stress, such as oxidative stress. Given the yet unmet suitability of ROS as targets for the intervention of cardiovascular disease, the endogenous antioxidant capacity of Plins may be beneficial.
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Affiliation(s)
- Mathieu Cinato
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden; (M.C.); (L.A.); (A.M.); (M.L.); (J.B.)
| | - Linda Andersson
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden; (M.C.); (L.A.); (A.M.); (M.L.); (J.B.)
| | - Azra Miljanovic
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden; (M.C.); (L.A.); (A.M.); (M.L.); (J.B.)
| | - Marion Laudette
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden; (M.C.); (L.A.); (A.M.); (M.L.); (J.B.)
| | - Oksana Kunduzova
- Institute of Metabolic and Cardiovascular Diseases (I2MC), National Institute of Health and Medical Research (INSERM) 1297, Toulouse III University—Paul Sabatier, 31432 Toulouse, France;
| | - Jan Borén
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden; (M.C.); (L.A.); (A.M.); (M.L.); (J.B.)
| | - Malin C. Levin
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden; (M.C.); (L.A.); (A.M.); (M.L.); (J.B.)
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Al Saedi A, Debruin DA, Hayes A, Hamrick M. Lipid metabolism in sarcopenia. Bone 2022; 164:116539. [PMID: 36007811 DOI: 10.1016/j.bone.2022.116539] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/10/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022]
Abstract
Sarcopenia is an age-related disease associated with loss of muscle mass and strength. This geriatric syndrome predisposes elderly individuals to a disability, falls, fractures, and death. Fat infiltration in muscle is one of the hallmarks of sarcopenia and aging. Alterations in fatty acid (FA) metabolism are evident in aging, type 2 diabetes, and obesity, with the accumulation of lipids inside muscle cells contributing to muscle insulin resistance and ceramide accumulation. These lipids include diacylglycerol, lipid droplets, intramyocellular lipids, intramuscular triglycerides, and polyunsaturated fatty acids (PUFAs). In this review, we examine the regulation of lipid metabolism in skeletal muscle, including lipid metabolization and storage, intervention, and the types of lipases expressed in skeletal muscle responsible for the breakdown of adipose triglyceride fats. In addition, we address the role of FAs in sarcopenia and the potential benefits of PUFAs.
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Affiliation(s)
- Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia; Institute of Health and Sport (IHeS), Victoria University, Melbourne, VIC, Australia.
| | - Danielle A Debruin
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia; Institute of Health and Sport (IHeS), Victoria University, Melbourne, VIC, Australia
| | - Alan Hayes
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia; Institute of Health and Sport (IHeS), Victoria University, Melbourne, VIC, Australia
| | - Mark Hamrick
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Laney Walker Blvd. CB2915, Augusta, GA 30912, USA
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Plin5, a New Target in Diabetic Cardiomyopathy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:2122856. [PMID: 35509833 PMCID: PMC9060988 DOI: 10.1155/2022/2122856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/14/2022] [Accepted: 04/06/2022] [Indexed: 02/07/2023]
Abstract
Abnormal lipid accumulation is commonly observed in diabetic cardiomyopathy (DC), which can create a lipotoxic microenvironment and damage cardiomyocytes. Lipid toxicity is an important pathogenic factor due to abnormal lipid accumulation in DC. As a lipid droplet (LD) decomposition barrier, Plin5 can protect LDs from lipase decomposition and regulate lipid metabolism, which is involved in the occurrence and development of cardiovascular diseases. In recent years, studies have shown that Plin5 expression is involved in the pathogenesis of DC lipid toxicity, such as oxidative stress, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and insulin resistance (IR) and has become a key target of DC research. Therefore, understanding the relationship between Plin5 and DC progression as well as the mechanism of this process is crucial for developing new therapeutic approaches and exploring new therapeutic targets. This review is aimed at exploring the latest findings and roles of Plin5 in lipid metabolism and DC-related pathogenesis, to explore possible clinical intervention approaches.
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Barrett JS, Whytock KL, Strauss JA, Wagenmakers AJM, Shepherd SO. High intramuscular triglyceride turnover rates and the link to insulin sensitivity: influence of obesity, type 2 diabetes and physical activity. Appl Physiol Nutr Metab 2022; 47:343-356. [PMID: 35061523 DOI: 10.1139/apnm-2021-0631] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large intramuscular triglyceride (IMTG) stores in sedentary, obese individuals have been linked to insulin resistance, yet well-trained athletes exhibit high IMTG levels whilst maintaining insulin sensitivity. Contrary to previous assumptions, it is now known that IMTG content per se does not result in insulin resistance. Rather, insulin resistance is caused, at least in part, by the presence of high concentrations of harmful lipid metabolites, such as diacylglycerols and ceramides in muscle. Several mechanistic differences between obese sedentary individuals and their highly trained counterparts have been identified, which determine the differential capacity for IMTG synthesis and breakdown in these populations. In this review, we first describe the most up-to-date mechanisms by which a low IMTG turnover rate (both breakdown and synthesis) leads to the accumulation of lipid metabolites and results in skeletal muscle insulin resistance. We then explore current and potential exercise and nutritional strategies that target IMTG turnover in sedentary obese individuals, to improve insulin sensitivity. Overall, improving IMTG turnover should be an important component of successful interventions that aim to prevent the development of insulin resistance in the ever-expanding sedentary, overweight and obese populations. Novelty: A description of the most up-to-date mechanisms regulating turnover of the IMTG pool. An exploration of current and potential exercise/nutritional strategies to target and enhance IMTG turnover in obese individuals. Overall, highlights the importance of improving IMTG turnover to prevent the development of insulin resistance.
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Affiliation(s)
- J S Barrett
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - K L Whytock
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - J A Strauss
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - A J M Wagenmakers
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - S O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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Plin5 Bidirectionally Regulates Lipid Metabolism in Oxidative Tissues. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:4594956. [PMID: 35401929 PMCID: PMC8989587 DOI: 10.1155/2022/4594956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 10/08/2021] [Accepted: 03/16/2022] [Indexed: 11/20/2022]
Abstract
Cytoplasmic lipid droplets (LDs) can store neutral lipids as an energy source when needed and also regulate the key metabolic processes of intracellular lipid accumulation, which is associated with several metabolic diseases. The perilipins (Plins) are a family of proteins that associate with the surface of LDs. As a member of Plins superfamily, perilipin 5 (Plin5) coats LDs in cardiomyocytes, which is significantly related to reactive oxygen species (ROS) production originated from mitochondria in the heart, consequently determining the progression of diabetic cardiomyopathy. Plin5 may play a bidirectional function in lipid metabolism which is in a state of dynamic balance. In the basic state, Plin5 inhibited the binding of comparative gene identification-58 (CGI-58) to adipose triglyceride lipase (ATGL) by binding CGI-58, thus inhibiting lipolysis. However, when the body is under stress (such as cold, fasting, exercise, and other stimuli), protein kinase A (PKA) phosphorylates and activates Plin5, which then causes Plin5 to release the binding site of CGI-58 and ATGL, prompting CGI-58 to bind to ATGL and activate ATGL activity, thus accelerating the lipolysis process, revealing the indispensable role of Plin5 in lipid turnover. Here, the purpose of this review is to summarize the present understanding of the bidirectional regulation role of Plin5 in oxidative tissues and to reveal its potential role in diabetic cardiomyopathy protection.
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Lipid Droplets, Phospholipase A 2, Arachidonic Acid, and Atherosclerosis. Biomedicines 2021; 9:biomedicines9121891. [PMID: 34944707 PMCID: PMC8699036 DOI: 10.3390/biomedicines9121891] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/01/2021] [Accepted: 12/10/2021] [Indexed: 02/07/2023] Open
Abstract
Lipid droplets, classically regarded as static storage organelles, are currently considered as dynamic structures involved in key processes of lipid metabolism, cellular homeostasis and signaling. Studies on the inflammatory state of atherosclerotic plaques suggest that circulating monocytes interact with products released by endothelial cells and may acquire a foamy phenotype before crossing the endothelial barrier and differentiating into macrophages. One such compound released in significant amounts into the bloodstream is arachidonic acid, the common precursor of eicosanoids, and a potent inducer of neutral lipid synthesis and lipid droplet formation in circulating monocytes. Members of the family of phospholipase A2, which hydrolyze the fatty acid present at the sn-2 position of phospholipids, have recently emerged as key controllers of lipid droplet homeostasis, regulating their formation and the availability of fatty acids for lipid mediator production. In this paper we discuss recent findings related to lipid droplet dynamics in immune cells and the ways these organelles are involved in regulating arachidonic acid availability and metabolism in the context of atherosclerosis.
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Przygrodzka E, Plewes MR, Davis JS. Luteinizing Hormone Regulation of Inter-Organelle Communication and Fate of the Corpus Luteum. Int J Mol Sci 2021; 22:9972. [PMID: 34576135 PMCID: PMC8470545 DOI: 10.3390/ijms22189972] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 12/18/2022] Open
Abstract
The corpus luteum is an endocrine gland that synthesizes the steroid hormone progesterone. luteinizing hormone (LH) is a key luteotropic hormone that stimulates ovulation, luteal development, progesterone biosynthesis, and maintenance of the corpus luteum. Luteotropic and luteolytic factors precisely regulate luteal structure and function; yet, despite recent scientific progress within the past few years, the exact mechanisms remain largely unknown. In the present review, we summarize the recent progress towards understanding cellular changes induced by LH in steroidogenic luteal cells. Herein, we will focus on the effects of LH on inter-organelle communication and steroid biosynthesis, and how LH regulates key protein kinases (i.e., AMPK and MTOR) responsible for controlling steroidogenesis and autophagy in luteal cells.
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Affiliation(s)
- Emilia Przygrodzka
- Olson Center for Women’s Health, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-3255, USA; (E.P.); (M.R.P.)
| | - Michele R. Plewes
- Olson Center for Women’s Health, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-3255, USA; (E.P.); (M.R.P.)
- Veterans Affairs Nebraska Western Iowa Health Care System, 4101 Woolworth Ave, Omaha, NE 68105, USA
| | - John S. Davis
- Olson Center for Women’s Health, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-3255, USA; (E.P.); (M.R.P.)
- Veterans Affairs Nebraska Western Iowa Health Care System, 4101 Woolworth Ave, Omaha, NE 68105, USA
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Black MN, Wilkinson JA, Webb EK, Kamal M, Bahniwal R, McGlory C, Phillips SM, Devries MC. Two weeks of single-leg immobilization alters intramyocellular lipid storage characteristics in healthy, young women. J Appl Physiol (1985) 2021; 130:1247-1258. [PMID: 33630674 DOI: 10.1152/japplphysiol.00878.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Muscle disuse rapidly induces insulin resistance (IR). Despite a relationship between intramyocellular lipid (IMCL) content and IR, during muscle-disuse IR develops before IMCL accumulation, suggesting that IMCL are not related to disuse-induced IR. However, recent studies show that it is not total IMCL content, but IMCL size and location that are related to IR. Changes in these IMCL parameters may occur prior to increases in IMCL content, thus contributing to disuse-induced IR. Omega-3 fatty acids may mitigate the effects of disuse on IR by preventing a decline in insulin signaling proteins. Twenty women (age 22 ± 3 yr) received either 5 g·day-1 omega-3 fatty acid or isoenergetic sunflower oil for 4 wk prior to, throughout 2 wk of single-leg immobilization, and during 2 wk of recovery. Changes in IMCL characteristics and insulin signaling proteins were examined in vastus lateralis samples taken before supplementation and immobilization, and following immobilization and recovery. Omega-3 supplementation had no effect. IMCL area density decreased in the subsarcolemmal region during immobilization and recovery (-19% and -56%, respectively, P = 0.009). IMCL size increased in the central intermyofibrillar region during immobilization (43%, P = 0.007), returning to baseline during recovery. PLIN5 and AKT increased during immobilization (87%, P = 0.002; 30%, P = 0.007, respectively). PLIN 5 remained elevated and AKT increased further (15%) during recovery. IRS1, AS160, and GLUT4 decreased during immobilization (-35%, P = 0.001; -44%, P = 0.03; -56%, P = 0.02, respectively), returning to baseline during recovery. Immobilization alters IMCL storage characteristics while negatively affecting unstimulated insulin signaling protein content in young women.NEW & NOTEWORTHY We report that the subcellular storage location of IMCL is altered by limb immobilization, highlighting the need to evaluate IMCL storage location when assessing the effects of disuse on IMCL content. We also found that AKT content increased during immobilization in our female population, contrary to studies in males finding that AKT decreases during disuse, highlighting that men and women may respond differently to disuse and the necessity to include women in all research.
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Affiliation(s)
- Merryl N Black
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Erin K Webb
- Department of Kinesiology, University of McMaster, Hamilton, Ontario, Canada
| | - Michael Kamal
- Department of Kinesiology, University of McMaster, Hamilton, Ontario, Canada
| | - Ravninder Bahniwal
- Department of Kinesiology, University of McMaster, Hamilton, Ontario, Canada
| | - Chris McGlory
- Department of Kinesiology, University of McMaster, Hamilton, Ontario, Canada
| | - Stuart M Phillips
- Department of Kinesiology, University of McMaster, Hamilton, Ontario, Canada
| | - Michaela C Devries
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Steiner JL, Johnson BR, Hickner RC, Ormsbee MJ, Williamson DL, Gordon BS. Adrenal stress hormone action in skeletal muscle during exercise training: An old dog with new tricks? Acta Physiol (Oxf) 2021; 231:e13522. [PMID: 32506657 DOI: 10.1111/apha.13522] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 05/29/2020] [Accepted: 05/29/2020] [Indexed: 12/12/2022]
Abstract
Exercise is a key component of a healthy lifestyle as it helps maintain a healthy body weight and reduces the risk of various morbidities and co-morbidities. Exercise is an acute physiological stress that initiates a multitude of processes that attempt to restore physiological homeostasis and promote adaptation. A component of the stress response to exercise is the rapid release of hormones from the adrenal gland including glucocorticoids, the catecholamines and aldosterone. While each hormone targets several tissues throughout the body, skeletal muscle is of interest as it is central to physical function and various metabolic processes. Indeed, adrenal stress hormones have been shown to elicit specific performance benefits on the muscle. However, how the acute, short-lived release of these stress hormones during exercise influences adaptations of skeletal muscle to long-term training remains largely unknown. Thus, the objective of this review was to briefly highlight the known impact of adrenal stress hormones on skeletal muscle metabolism and function (Old Dog), and critically examine the current evidence supporting a role for these endogenous hormones in mediating long-term training adaptations in skeletal muscle (New Tricks).
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Affiliation(s)
- Jennifer L. Steiner
- Department of Nutrition, Food and Exercise Sciences Florida State University Tallahassee FL USA
- Institute of Sports Sciences and Medicine Florida State University Tallahassee FL USA
| | - Bonde R. Johnson
- Department of Nutrition, Food and Exercise Sciences Florida State University Tallahassee FL USA
| | - Robert C. Hickner
- Department of Nutrition, Food and Exercise Sciences Florida State University Tallahassee FL USA
- Institute of Sports Sciences and Medicine Florida State University Tallahassee FL USA
- Department of Biokinetics, Exercise and Leisure Sciences University of KwaZulu‐Natal Durban South Africa
| | - Michael J. Ormsbee
- Department of Nutrition, Food and Exercise Sciences Florida State University Tallahassee FL USA
- Institute of Sports Sciences and Medicine Florida State University Tallahassee FL USA
- Department of Biokinetics, Exercise and Leisure Sciences University of KwaZulu‐Natal Durban South Africa
| | - David L. Williamson
- Kinesiology Program School of Behavioral Sciences and Education Pennsylvania State University at Harrisburg Middletown PA USA
| | - Bradley S. Gordon
- Department of Nutrition, Food and Exercise Sciences Florida State University Tallahassee FL USA
- Institute of Sports Sciences and Medicine Florida State University Tallahassee FL USA
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Hofer P, Taschler U, Schreiber R, Kotzbeck P, Schoiswohl G. The Lipolysome-A Highly Complex and Dynamic Protein Network Orchestrating Cytoplasmic Triacylglycerol Degradation. Metabolites 2020; 10:E147. [PMID: 32290093 PMCID: PMC7240967 DOI: 10.3390/metabo10040147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 12/25/2022] Open
Abstract
The catabolism of intracellular triacylglycerols (TAGs) involves the activity of cytoplasmic and lysosomal enzymes. Cytoplasmic TAG hydrolysis, commonly termed lipolysis, is catalyzed by the sequential action of three major hydrolases, namely adipose triglyceride lipase, hormone-sensitive lipase, and monoacylglycerol lipase. All three enzymes interact with numerous protein binding partners that modulate their activity, cellular localization, or stability. Deficiencies of these auxiliary proteins can lead to derangements in neutral lipid metabolism and energy homeostasis. In this review, we summarize the composition and the dynamics of the complex lipolytic machinery we like to call "lipolysome".
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Affiliation(s)
- Peter Hofer
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Petra Kotzbeck
- Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria;
| | - Gabriele Schoiswohl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
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Plin5/p-Plin5 Guards Diabetic CMECs by Regulating FFAs Metabolism Bidirectionally. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8690746. [PMID: 31772713 PMCID: PMC6854993 DOI: 10.1155/2019/8690746] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 07/23/2019] [Indexed: 01/02/2023]
Abstract
Background Hyper-free fatty acidemia (HFFA) impairs cardiac capillaries, as well as type 2 diabetes mellitus (T2DM). Perilipin 5 (Plin5) maintains metabolic balance of free fatty acids (FFAs) in high oxidative tissues via the states of nonphosphorylation and phosphorylation. However, when facing to T2DM-HFFA, Plin5's role in cardiac microvascular endothelial cells (CMECs) is not defined. Methods In mice of WT or Plin5−/−, T2DM models were rendered by high-fat diet combined with intraperitoneal injection of streptozocin. CMECs isolated from left ventricles were incubated with high glucose (HG) and high FFAs (HFFAs). Plin5 phosphorylation was stimulated by isoproterenol. Plin5 expression was knocked down by small interfering RNA (siRNA). We determined cardiac function by small animal ultrasound, apoptotic rate by flow cytometry, microvessel quantity by immunohistochemistry, microvascular integrity by scanning electron microscopy, intracellular FFAs by spectrophotometry, lipid droplets (LDs) by Nile red staining, mRNAs by quantitative real-time polymerase chain reaction, proteins by western blots, nitric oxide (NO) and reactive oxygen species (ROS) by fluorescent dye staining and enzyme-linked immunosorbent assay kits. Results In CMECs, HFFAs aggravated cell injury induced by HG and activated Plin5 expression. In mice with T2DM-HFFA, Plin5 deficiency reduced number of cardiac capillaries, worsened structural incompleteness, and enhanced diastolic dysfunction. Moreover, in CMECs treated with HG-HFFAs, both ablation and phosphorylation of Plin5 reduced LDs content, increased intracellular FFAs, stimulated mitochondrial β-oxidation, added ROS generation, and reduced the expression and activity of endothelial nitric oxide synthase (eNOS), eventually leading to increased apoptotic rate and decreased NO content, all of which were reversed by N-acetyl-L-cysteine. Conclusion Plin5 preserves lipid balance and cell survival in diabetic CMECs by regulating FFAs metabolism bidirectionally via the states of nonphosphorylation and phosphorylation.
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Hargreaves M, Spriet LL. Exercise Metabolism: Fuels for the Fire. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a029744. [PMID: 28533314 DOI: 10.1101/cshperspect.a029744] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During exercise, the supply of adenosine triphosphate (ATP) is essential for the energy-dependent processes that underpin ongoing contractile activity. These pathways involve both substrate-level phosphorylation, without any need for oxygen, and oxidative phosphorylation that is critically dependent on oxygen delivery to contracting skeletal muscle by the respiratory and cardiovascular systems and on the supply of reducing equivalents from the degradation of carbohydrate, fat, and, to a limited extent, protein fuel stores. The relative contribution of these pathways is primarily determined by exercise intensity, but also modulated by training status, preceding diet, age, gender, and environmental conditions. Optimal substrate availability and utilization before, during, and after exercise is critical for maintaining exercise performance. This review provides a brief overview of exercise metabolism, with expanded discussion of the regulation of muscle glucose uptake and fatty acid uptake and oxidation.
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Affiliation(s)
- Mark Hargreaves
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
| | - Lawrence L Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Ko K, Woo J, Bae JY, Roh HT, Lee YH, Shin KO. Exercise training improves intramuscular triglyceride lipolysis sensitivity in high-fat diet induced obese mice. Lipids Health Dis 2018; 17:81. [PMID: 29661202 PMCID: PMC5902881 DOI: 10.1186/s12944-018-0730-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 04/03/2018] [Indexed: 12/29/2022] Open
Abstract
Background The purpose of this study was to determine whether regular exercise training enhances intramuscular triglyceride (IMTG) lipolysis sensitivity during consumption of a continued high-fat diet by exploring changes in biochemical factors activated by IMTG lipolysis. Methods Male C57BL/6 mice aged 4 weeks were randomly divided into a high-fat diet group (HF) to induce obesity for 6 weeks and a control (CO) group. Thereafter, the HF group was divided into a high-fat diet group (HF) and high-fat diet + training group (HFT). The HFT group was trained on an animal treadmill 40 min/day, 5 days/week for 8 weeks. PKA, Plin5, p-Plin5, CGI-58, ATGL, and HSL were analyzed to investigate IMTG sensitivity by western blotting. Results PKA, CGI-58, and HSL protein levels in the HF group were significantly lower than those in the CO group (p < 0.05). However, PKA, CGI-58, and HSL protein levels in the HFT group were significantly higher than those in the HF group, and ATGL and p-Plin5 protein levels as well as the p-Plin5/Plin5 ratio in the HFT group were significantly higher than those in the HF group (p < 0.05). In addition, the HF group showed a significantly higher IMTG volume than the CO and HFT groups (p < 0.05). Conclusions These results suggest that in an obese mouse model, 8 weeks of treadmill exercise contributes to decreased IMTG volume by activating lipolysis factors, such as PKA, PLIN5, CGI-58, and lipases. Therefore, regular exercise training may play an important role in obesity treatment by increasing IMTG lipolysis sensitivity.
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Affiliation(s)
- Kangeun Ko
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 49315, Republic of Korea
| | - Jinhee Woo
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 49315, Republic of Korea
| | - Ju Yong Bae
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 49315, Republic of Korea
| | - Hee Tae Roh
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 49315, Republic of Korea
| | - Yul Hyo Lee
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 49315, Republic of Korea
| | - Ki Ok Shin
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 49315, Republic of Korea.
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14
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Zhang P, Meng L, Song L, Du J, Du S, Cui W, Liu C, Li F. Roles of Perilipins in Diseases and Cancers. Curr Genomics 2018; 19:247-257. [PMID: 29755288 PMCID: PMC5930447 DOI: 10.2174/1389202918666170915155948] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/03/2017] [Accepted: 04/25/2017] [Indexed: 12/14/2022] Open
Abstract
Perilipins, an ancient family of lipid droplet-associated proteins, are embedded in a phospho-lipid monolayer of intracellular lipid droplets. The core of lipid droplets is composed of neutral fat, which mainly includes triglyceride and cholesterol ester. Perilipins are closely related to the function of lipid droplets, and they mediate lipid metabolism and storage. Therefore, perilipins play an important role in the development of obesity, diabetes, cancer, hepatic diseases, atherosclerosis, and carcinoma, which are caused by abnormal lipid metabolism. Accumulation of lipid droplets is a common phenomenon in tumor cells. Available data on the pathophysiology of perilipins and the relationship of perilipins with endocrine metabolic diseases and cancers are summarized in this mini-review. The research progress on this family offers novel insights into the therapeutic strategies for these diseases.
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Affiliation(s)
- Pengpeng Zhang
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Lian Meng
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Lingxie Song
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Juan Du
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Shutong Du
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Wenwen Cui
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Chunxia Liu
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China
| | - Feng Li
- Department of Pathology and The Key Laboratories for Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, Xinjiang, China.,Department of Pathology, Beijing Chaoyang Hospital, Capital Medical University, Beijing100020, China
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15
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Lundsgaard AM, Fritzen AM, Kiens B. Molecular Regulation of Fatty Acid Oxidation in Skeletal Muscle during Aerobic Exercise. Trends Endocrinol Metab 2018; 29:18-30. [PMID: 29221849 DOI: 10.1016/j.tem.2017.10.011] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/28/2017] [Accepted: 10/30/2017] [Indexed: 01/21/2023]
Abstract
This review summarizes how fatty acid (FA) oxidation is regulated in skeletal muscle during exercise. From the available evidence it seems that acetyl-CoA availability in the mitochondrial matrix adjusts FA oxidation to exercise intensity and duration. This is executed at the step of mitochondrial fatty acyl import, as the extent of acetyl group sequestration by carnitine determines the availability of carnitine for the carnitine palmitoyltransferase 1 (CPT1) reaction. The rate of glycolysis seems therefore to be central to the amount of β-oxidation-derived acetyl-CoA that is oxidized in the tricarboxylic acid (TCA) cycle. FA oxidation during exercise is also determined by FA availability to mitochondria, dependent on trans-sarcolemmal FA uptake via cluster of differentiation 36/SR-B2 (CD36) and FAs mobilized from myocellular lipid droplets.
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Affiliation(s)
- Anne-Marie Lundsgaard
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Mæchel Fritzen
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
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16
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Gao X, Nan Y, Zhao Y, Yuan Y, Ren B, Sun C, Cao K, Yu M, Feng X, Ye J. Atorvastatin reduces lipid accumulation in the liver by activating protein kinase A-mediated phosphorylation of perilipin 5. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1512-1519. [PMID: 28919478 DOI: 10.1016/j.bbalip.2017.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 06/28/2017] [Accepted: 09/10/2017] [Indexed: 01/01/2023]
Abstract
Statins have been proven to be effective in treating non-alcoholic fatty liver disease (NAFLD). Recently, it was reported that statins decreased the hepatic expression of perilipin 5 (Plin5), a lipid droplet (LD)-associated protein, which plays critical roles in regulating lipid accumulation and lipolysis in liver. However, the function and regulation mechanism of Plin5 have not yet been well-established in NAFLD treatment with statins. In this study, we observed that atorvastatin moderately reduced the expression of Plin5 in livers without changing the protein level of Plin5 in the hepatic LD fraction of mice fed with high-fat diet (HFD). Intriguingly, atorvastatin stimulated the PKA-mediated phosphorylation of Plin5 and reduced the triglyceride (TG) accumulation in hepatocytes with overexpression of wide type (Plin5-WT) compared to serine-155 mutant Plin5 (Plin5-S155A). Moreover, PKA-stimulated FA release of purified LDs carrying Plin5-WT but not Plin5-S155A. Glucagon, a PKA activator, stimulated the phosphorylation of Plin5-WT and inhibited its interaction with CGI-58. The results indicated that atorvastatin promoted lipolysis and reduced TG accumulation in the liver by increasing PKA-mediated phosphorylation of Plin5. This new mechanism of lipid-lowering effects of atorvastatin might provide a new strategy for NAFLD treatment.
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Affiliation(s)
- Xing Gao
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Yang Nan
- Department of Gynecology, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Yuanlin Zhao
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Yuan Yuan
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Bincheng Ren
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Chao Sun
- Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Kaiyu Cao
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Ming Yu
- Department of Ultrasonography, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Xuyang Feng
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
| | - Jing Ye
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
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17
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Kimmel AR, Sztalryd C. The Perilipins: Major Cytosolic Lipid Droplet-Associated Proteins and Their Roles in Cellular Lipid Storage, Mobilization, and Systemic Homeostasis. Annu Rev Nutr 2017; 36:471-509. [PMID: 27431369 DOI: 10.1146/annurev-nutr-071813-105410] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery by Dr. Constantine Londos of perilipin 1, the major scaffold protein at the surface of cytosolic lipid droplets in adipocytes, marked a fundamental conceptual change in the understanding of lipolytic regulation. Focus then shifted from the enzymatic activation of lipases to substrate accessibility, mediated by perilipin-dependent protein sequestration and recruitment. Consequently, the lipid droplet became recognized as a unique, metabolically active cellular organelle and its surface as the active site for novel protein-protein interactions. A new area of investigation emerged, centered on lipid droplets' biology and their role in energy homeostasis. The perilipin family is of ancient origin and has expanded to include five mammalian genes and a growing list of evolutionarily conserved members. Universally, the perilipins modulate cellular lipid storage. This review provides a summary that connects the perilipins to both cellular and whole-body homeostasis.
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Affiliation(s)
- Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
| | - Carole Sztalryd
- The Geriatric Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201.,Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201;
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18
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Kong BW, Hudson N, Seo D, Lee S, Khatri B, Lassiter K, Cook D, Piekarski A, Dridi S, Anthony N, Bottje W. RNA sequencing for global gene expression associated with muscle growth in a single male modern broiler line compared to a foundational Barred Plymouth Rock chicken line. BMC Genomics 2017; 18:82. [PMID: 28086790 PMCID: PMC5237145 DOI: 10.1186/s12864-016-3471-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/23/2016] [Indexed: 01/08/2023] Open
Abstract
Background Modern broiler chickens exhibit very rapid growth and high feed efficiency compared to unselected chicken breeds. The improved production efficiency in modern broiler chickens was achieved by the intensive genetic selection for meat production. This study was designed to investigate the genetic alterations accumulated in modern broiler breeder lines during selective breeding conducted over several decades. Methods To identify genes important in determining muscle growth and feed efficiency in broilers, RNA sequencing (RNAseq) was conducted with breast muscle in modern pedigree male (PeM) broilers (n = 6 per group), and with an unselected foundation broiler line (Barred Plymouth Rock; BPR). The RNAseq analysis was carried out using Ilumina Hiseq (2 x 100 bp paired end read) and raw reads were assembled with the galgal4 reference chicken genome. With normalized RPM values, genes showing >10 average read counts were chosen and genes showing <0.05 p-value and >1.3 fold change were considered as differentially expressed (DE) between PeM and BPR. DE genes were subjected to Ingenuity Pathway Analysis (IPA) for bioinformatic functional interpretation. Results The results indicate that 2,464 DE genes were identified in the comparison between PeM and BPR. Interestingly, the expression of genes encoding mitochondrial proteins in chicken are significantly biased towards the BPR group, suggesting a lowered mitochondrial content in PeM chicken muscles compared to BPR chicken. This result is inconsistent with more slow muscle fibers bearing a lower mitochondrial content in the PeM. The molecular, cellular and physiological functions of DE genes in the comparison between PeM and BPR include organismal injury, carbohydrate metabolism, cell growth/proliferation, and skeletal muscle system development, indicating that cellular mechanisms in modern broiler lines are tightly associated with rapid growth and differential muscle fiber contents compared to the unselected BPR line. Particularly, PDGF (platelet derived growth factor) signaling and NFE2L2 (nuclear factor, erythroid 2-like 2; also known as NRF2) mediated oxidative stress response pathways appear to be activated in modern broiler compared to the foundational BPR line. Upstream and network analyses revealed that the MSTN (myostatin) –FST (follistatin) interactions and inhibition of AR (androgen receptor) were predicted to be effective regulatory factors for DE genes in modern broiler line. PRKAG3 (protein kinase, AMP-activated, gamma 3 non-catalytic subunit) and LIPE (lipase E) are predicted as core regulatory factors for myogenic development, nutrient and lipid metabolism. Conclusion The highly upregulated genes in PeM may represent phenotypes of subclinical myopathy commonly observed in the commercial broiler breast tissue, that can lead to muscle hardening, named as woody breast. By investigating global gene expression in a highly selected pedigree broiler line and a foundational breed (Barred Plymouth Rock), the results provide insight into cellular mechanisms that regulate muscle growth, fiber composition and feed efficiency. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3471-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Byung-Whi Kong
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Nicholas Hudson
- School of Agriculture and Food Science, University of Queensland, Gatton, Australia
| | - Dongwon Seo
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Seok Lee
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Bhuwan Khatri
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Kentu Lassiter
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Devin Cook
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Alissa Piekarski
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Sami Dridi
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Nicholas Anthony
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA
| | - Walter Bottje
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA.
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19
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Morales PE, Bucarey JL, Espinosa A. Muscle Lipid Metabolism: Role of Lipid Droplets and Perilipins. J Diabetes Res 2017; 2017:1789395. [PMID: 28676863 PMCID: PMC5476901 DOI: 10.1155/2017/1789395] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 04/19/2017] [Accepted: 04/26/2017] [Indexed: 02/07/2023] Open
Abstract
Skeletal muscle is one of the main regulators of carbohydrate and lipid metabolism in our organism, and therefore, it is highly susceptible to changes in glucose and fatty acid (FA) availability. Skeletal muscle is an extremely complex tissue: its metabolic capacity depends on the type of fibers it is made up of and the level of stimulation it undergoes, such as acute or chronic contraction. Obesity is often associated with increased FA levels, which leads to the accumulation of toxic lipid intermediates, oxidative stress, and autophagy in skeletal fibers. This lipotoxicity is one of the most common causes of insulin resistance (IR). In this scenario, the "isolation" of certain lipids in specific cell compartments, through the action of the specific lipid droplet, perilipin (PLIN) family of proteins, is conceived as a lifeguard compensatory strategy. In this review, we summarize the cellular mechanism underlying lipid mobilization and metabolism inside skeletal muscle, focusing on the function of lipid droplets, the PLIN family of proteins, and how these entities are modified in exercise, obesity, and IR conditions.
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Affiliation(s)
- Pablo Esteban Morales
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Jose Luis Bucarey
- CIDIS-AC, Escuela de Medicina, Universidad de Valparaiso, Valparaiso, Chile
| | - Alejandra Espinosa
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Center for Molecular Studies of the Cell, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- *Alejandra Espinosa:
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20
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Ramos SV, Turnbull PC, MacPherson REK. Adipose tissue depot specific differences of PLIN protein content in endurance trained rats. Adipocyte 2016; 5:212-23. [PMID: 27386161 DOI: 10.1080/21623945.2016.1157672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 02/11/2016] [Accepted: 02/17/2016] [Indexed: 12/15/2022] Open
Abstract
Adipose tissue is classified as either white (WAT) or brown (BAT) and differs not only by anatomical location but also in function. WAT is the main source of stored energy and releases fatty acids in times of energy demand, whereas BAT plays a role in regulating non-shivering thermogenesis and oxidizes fatty acids released from the lipid droplet. The PLIN family of proteins has recently emerged as being integral in the regulation of fatty acid storage and release in adipose tissue. Previous work has demonstrated that PLIN protein content varies among adipose tissue depots, however an examination of endurance training-induced depot specific changes in PLIN protein expression has yet to be done. Male Sprague-dawley rats (n = 10) underwent 8-weeks of progressive treadmill training (18-25 m/min for 30-60 min at 10% incline) or remained sedentary as control. Following training, under isoflurane induced anesthesia epidydmal (eWAT), inguinal subcutaneous (iWAT) and intrascapular brown adipose tissue (BAT) was excised, and plasma was collected. Endurance training resulted in an increase in BAT PLIN5 and iWAT PLIN3 content, while there was no difference in PLIN protein content in endurance trained eWAT. Interestingly, endurance training resulted in a robust increase in ATGL and CGI-58 in eWAT alone. Together these results suggest the potential of a depot specific function of PLIN3 and PLIN5 in adipose tissue in response to endurance training.
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Affiliation(s)
- Sofhia V. Ramos
- Department of Kinesiology, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Patrick C. Turnbull
- Department of Kinesiology, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
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21
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Noland RC. Exercise and Regulation of Lipid Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:39-74. [PMID: 26477910 DOI: 10.1016/bs.pmbts.2015.06.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The increased prevalence of hyperlipidemia, hypertriglyceridemia, hypercholesterolemia, and fatty liver disease has provided increasingly negative connotations toward lipids. However, it is important to remember that lipids are essential components supporting life. Lipids are a class of molecules defined by their inherent insolubility in water. In biological systems, lipids are either hydrophobic (containing only polar groups) or amphipathic (possess polar and nonpolar groups). These characteristics lend lipids to be highly diverse with a multitude of functions including hormone and membrane synthesis, involvement in numerous signaling cascades, as well as serving as a source of metabolic fuel supporting energy production. Exercise can induce changes in the lipid composition of membranes that effect fluidity and cellular function, as well as modify the cellular and circulating environment of lipids that regulate signaling cascades. The purpose of this chapter is to focus on lipid utilization as metabolic fuel in response to acute and chronic exercise training. Lipids utilized as an energy source during exercise include circulating fatty acids bound to albumin, triglycerides stored in very-low-density lipoprotein, and intramuscular triglyceride stores. Dynamic changes in these lipid pools during and after exercise are discussed, as well as key factors that may be responsible for regulating changes in fat oxidation in response to varying exercise conditions.
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Affiliation(s)
- Robert C Noland
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, USA.
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22
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Ramos SV, Turnbull PC, MacPherson REK, LeBlanc PJ, Ward WE, Peters SJ. Changes in mitochondrial perilipin 3 and perilipin 5 protein content in rat skeletal muscle following endurance training and acute stimulated contraction. Exp Physiol 2015; 100:450-62. [PMID: 25663294 DOI: 10.1113/expphysiol.2014.084434] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/27/2015] [Indexed: 01/15/2023]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to determine whether mitochondrial protein content of perilipin 3 (PLIN3) and perilipin 5 (PLIN5) is increased following endurance training and whether mitochondrial PLIN5 protein is increased to a greater extent in endurance-trained rats when compared with sedentary rats following acute contraction. What is the main finding and its importance? Mitochondrial PLIN3 but not PLIN5 protein was increased in endurance-trained compared with sedentary rats, suggesting a mitochondrial role for PLIN3 due to chronic exercise. Contrary to our hypothesis, acute mitochondrial PLIN5 protein was similar in both sedentary and endurance-trained rats. Endurance training results in an increased association between skeletal muscle lipid droplets and mitochondria. This association is likely to be important for the expected increase in intramuscular fatty acid oxidation that occurs with endurance training. The perilipin family of lipid droplet proteins, PLIN(2-5), are thought to play a role in skeletal muscle lipolysis. Recently, results from our laboratory demonstrated that skeletal muscle mitochondria contain PLIN3 and PLIN5 protein. Furthermore, 30 min of stimulated contraction induces an increased mitochondrial PLIN5 content. To determine whether mitochondrial content of PLIN3 and PLIN5 is altered with endurance training, Sprague-Dawley rats were randomized into sedentary or endurance-trained groups for 8 weeks of treadmill running followed by an acute (30 min) sciatic nerve stimulation to induce lipolysis. Mitochondrial PLIN3 protein was ∼1.5-fold higher in red gastrocnemius of endurance-trained rats compared with sedentary animals, with no change in mitochondrial PLIN5 protein. In addition, there was an increase in plantaris intramuscular lipid storage. Acute electrically stimulated contraction in red gastrocnemius from sedentary and endurance-trained rats resulted in a similar increase of mitochondrial PLIN5 between these two groups, with no net change in PLIN3 in either group. Plantaris intramuscular lipid content decreased to a similar extent in sedentary and endurance-trained rats. These results suggest that while total mitochondrial PLIN5 content is not altered by endurance training, PLIN5 does have an acute role in the mitochondrial fraction during muscle contraction. Conversely, mitochondrial PLIN3 does not change acutely with muscle contraction, but PLIN3 content was increased following endurance training, indicating a role in chronic adaptations of skeletal muscle.
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Affiliation(s)
- S V Ramos
- Center for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada; Department of Kinesiology, Brock University, St Catharines, Ontario, Canada
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23
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Mason RR, Watt MJ. Unraveling the roles of PLIN5: linking cell biology to physiology. Trends Endocrinol Metab 2015; 26:144-52. [PMID: 25682370 DOI: 10.1016/j.tem.2015.01.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 01/07/2023]
Abstract
The discovery of perilipin (PLIN) 1 provided a major conceptual shift in the understanding of adipose tissue lipolysis and generated intense interest in lipid droplet biology research. The subsequent discovery of other PLIN proteins revealed unique tissue distribution profiles, subcellular locations, and lipid-binding properties and divergent cellular functions. PLIN5 is highly expressed in oxidative tissues such as skeletal muscle, liver, and heart and is central to lipid homeostasis in these tissues. Studies in cell systems have ascribed several metabolic roles to PLIN5 and demonstrated interactions with other proteins that are requisite for these functions. We examine recent in vivo studies and ask whether the evidence from the cell biology approaches is consistent with the physiological roles of PLIN5.
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Affiliation(s)
- Rachael R Mason
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
| | - Matthew J Watt
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
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24
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MacPherson REK, Peters SJ. Piecing together the puzzle of perilipin proteins and skeletal muscle lipolysis. Appl Physiol Nutr Metab 2015; 40:641-51. [PMID: 25971423 DOI: 10.1139/apnm-2014-0485] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The regulation of skeletal muscle lipolysis and fat oxidation is a complex process involving multiple proteins and enzymes. Emerging work indicates that skeletal muscle PLIN proteins likely play a role in the hydrolysis of triglycerides stored in lipid droplets and the passage of fatty acids to the mitochondria for oxidation. In adipocytes, PLIN1 regulates lipolysis by interacting with comparative gene identification-58 (CGI-58), an activator of adipose triglyceride lipase (ATGL). Upon lipolytic stimulation, PLIN1 is phosphorylated, releasing CGI-58 to activate ATGL and initiate triglyceride breakdown. The absence of PLIN1 in skeletal muscle leads us to believe that other PLIN family members undertake this role. The focus of this review is on the PLIN family proteins expressed in skeletal muscle: PLIN2, PLIN3, and PLIN5. To date, most studies involving these PLIN proteins have used nonmuscle tissues and cell cultures to determine their potential roles. Results from work in these models support a role for PLIN proteins in sequestering lipases during basal conditions and in potentially working together for lipase translocation and activity during lipolysis. In skeletal muscle, PLIN2 tends to mirror the lipid content and may play a role in lipid droplet growth and stability through lipase interactions on the lipid droplet surface, whereas the skeletal muscle roles of both PLIN3 and PLIN5 seem to be more complex because they are found not only on the lipid droplet, but also at the mitochondria. Clearly, further work is needed to fully understand the intricate mechanisms by which PLIN proteins contribute to skeletal muscle lipid metabolism.
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Affiliation(s)
- Rebecca E K MacPherson
- a Center for Bone and Muscle Health, Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,b Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Sandra J Peters
- a Center for Bone and Muscle Health, Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
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25
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Pollak NM, Jaeger D, Kolleritsch S, Zimmermann R, Zechner R, Lass A, Haemmerle G. The interplay of protein kinase A and perilipin 5 regulates cardiac lipolysis. J Biol Chem 2015; 290:1295-306. [PMID: 25418045 PMCID: PMC4340377 DOI: 10.1074/jbc.m114.604744] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 11/21/2014] [Indexed: 12/21/2022] Open
Abstract
Defective lipolysis in mice lacking adipose triglyceride lipase provokes severe cardiac steatosis and heart dysfunction, markedly shortening life span. Similarly, cardiac muscle (CM)-specific Plin5 overexpression (CM-Plin5) leads to severe triglyceride (TG) accumulation in cardiomyocytes via impairing TG breakdown. Interestingly, cardiac steatosis due to overexpression of Plin5 is compatible with normal heart function and life span indicating a more moderate impact of Plin5 overexpression on cardiac lipolysis and energy metabolism. We hypothesized that cardiac Plin5 overexpression does not constantly impair cardiac lipolysis. In line with this assumption, TG levels decreased in CM of fasted compared with nonfasted CM-Plin5 mice indicating that fasting may lead to a diminished barrier function of Plin5. Recent studies demonstrated that Plin5 is phosphorylated, and activation of adenylyl cyclase leads to phosphorylation of Plin5, suggesting that Plin5 is a substrate for PKA. Furthermore, any significance of Plin5 phosphorylation by PKA in the regulation of TG mobilization from lipid droplets (LDs) is unknown. Here, we show that the lipolytic barrier of Plin5-enriched LDs, either prepared from cardiac tissue of CM-Plin5 mice or Plin5-transfected cells, is abrogated by incubation with PKA. Notably, PKA-induced lipolysis of LDs enriched with Plin5 carrying a single mutation at serine 155 (PlinS155A) of the putative PKA phosphorylation site was substantially impaired revealing a critical role for PKA in Plin5-regulated lipolysis. The strong increase in protein levels of phosphorylated PKA in CM of Plin5 transgenic mice may partially restore fatty acid release from Plin5-enriched LDs, rendering these hearts compatible with normal heart function despite massive steatosis.
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Affiliation(s)
- Nina M Pollak
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Doris Jaeger
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | | | - Robert Zimmermann
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Rudolf Zechner
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Achim Lass
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Guenter Haemmerle
- From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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26
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Conte M, Vasuri F, Bertaggia E, Armani A, Santoro A, Bellavista E, Degiovanni A, D'Errico-Grigioni A, Trisolino G, Capri M, Franchi MV, Narici MV, Sandri M, Franceschi C, Salvioli S. Differential expression of perilipin 2 and 5 in human skeletal muscle during aging and their association with atrophy-related genes. Biogerontology 2015; 16:329-40. [PMID: 25559404 DOI: 10.1007/s10522-014-9549-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/24/2014] [Indexed: 12/13/2022]
Abstract
Sarcopenia, the progressive loss of muscle mass and strength, is a phenomenon characterizing human aging whose etiology is still not clear. While there is increasing evidence for the influence of inter-muscular adipose tissue infiltration in the development of sarcopenia, much less is known about a possible role for intra-muscular triglycerides (IMTG). IMTG accumulate in form of lipid droplets decorated by proteins such as Perilipins (Plins). In skeletal muscle the most abundant are Plin2 and Plin5. In this study we compared the expression of these two Plins in Vastus lateralis muscle samples of subjects of different age, both healthy donors (HD) and patients with limited lower limb mobility (LLMI). These latter are characterized by a condition of chronic physical inactivity. Plin2 expression resulted higher in old age for both HD and LLMI patients, while Plin5 slightly decreased only in LLMI patients. Moreover, in these patients, only Plin2 was associated with the decrease of muscle strength and the expression of factors related to muscle atrophy (MuRF1, Atrogin and p53). An increase in Plin2 and a concomitant decrease of Plin5 was also observed when we considered animal model of disuse-induced muscle atrophy. As a whole, these data indicate that Plin2 and Plin5 have a different expression pattern during muscle aging and inactivity, and only Plin2 appears to be associated with functional alterations of the muscle.
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Affiliation(s)
- Maria Conte
- Department of Experimental, Diagnostic and Specialty Medicine and Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, via S. Giacomo 12, 40126, Bologna, Italy,
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27
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MacPherson REK, Castelli LM, Miotto PM, Frendo-Cumbo S, Milburn A, Roy BD, LeBlanc PJ, Ward WE, Peters SJ. A maternal high fat diet has long-lasting effects on skeletal muscle lipid and PLIN protein content in rat offspring at young adulthood. Lipids 2015; 50:205-17. [PMID: 25552350 DOI: 10.1007/s11745-014-3985-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 12/16/2014] [Indexed: 01/08/2023]
Abstract
A maternal high fat diet (HFD) can have adverse effects on skeletal muscle development. Skeletal muscle PLIN proteins (PLIN2, 3 and 5) are thought to play critical roles in lipid metabolism, however effects of HFD on PLIN and lipases (HSL, ATGL, CGI-58) in mothers as well as their offspring have yet to be investigated. The primary objective of this study was to determine whether maternal HFD would influence skeletal muscle lipase and PLIN protein content in offspring at weaning (19 d) and young adulthood (3 mo). Female rats (28 d old, n = 9/group) were fed control (CON, AIN93G, 7% soybean oil) or HFD (AIN93G, 20% lard) for 10 weeks prior to mating and throughout pregnancy and lactation. All offspring were weaned to CON [n = 18/group, 1 female and 1 male pup per litter were studied at weaning (19 d) and 3 mo of age]. There was no effect of sex for the main outcomes measured in plantaris, therefore male and female data was combined. Maternal HFD resulted in higher triacylglycerol content in pups at 3 mo (p < 0.05), as well as in the dams (p = 0.015). Maternal HFD resulted in higher PLIN5 content in pups at weaning and 3 mo (p = 0.05). PLIN2 and PLIN5 content decreased at 3 mo versus weaning (p < 0.001). HFD dams had a higher PLIN3 content (p = 0.016). Diet had no effect on ATGL, CGI-58, or HSL content. In conclusion, exposure to a maternal HFD resulted in higher skeletal muscle lipid and PLIN5 content in plantaris of offspring through to young adulthood.
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Affiliation(s)
- Rebecca E K MacPherson
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada,
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28
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Ramos SV, MacPherson REK, Turnbull PC, Bott KN, LeBlanc P, Ward WE, Peters SJ. Higher PLIN5 but not PLIN3 content in isolated skeletal muscle mitochondria following acute in vivo contraction in rat hindlimb. Physiol Rep 2014; 2:2/10/e12154. [PMID: 25318747 PMCID: PMC4254090 DOI: 10.14814/phy2.12154] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Contraction-mediated lipolysis increases the association of lipid droplets and mitochondria, indicating an important role in the passage of fatty acids from lipid droplets to mitochondria in skeletal muscle. PLIN3 and PLIN5 are of particular interest to the lipid droplet-mitochondria interaction because PLIN3 is able to move about within cells and PLIN5 associates with skeletal muscle mitochondria. This study primarily investigated: 1) if PLIN3 is detected in skeletal muscle mitochondrial fraction; and 2) if mitochondrial protein content of PLIN3 and/or PLIN5 changes following stimulated contraction. A secondary aim was to determine if PLIN3 and PLIN5 associate and whether this changes following contraction. Male Long Evans rats (n = 21; age, 52 days; weight = 317 ± 6 g) underwent 30 min of hindlimb stimulation (10 msec impulses, 100 Hz/3 sec at 10-20 V; train duration 100 msec). Contraction induced a ~50% reduction in intramuscular lipid content measured by oil red-O staining of red gastrocnemius muscle. Mitochondria were isolated from red gastrocnemius muscle by differential centrifugation and proteins were detected by western blotting. Mitochondrial PLIN5 content was ~1.6-fold higher following 30 min of contraction and PLIN3 content was detected in the mitochondrial fraction, and unchanged following contraction. An association between PLIN3 and PLIN5 was observed and remained unaltered following contraction. PLIN5 may play a role in mitochondria during lipolysis, which is consistent with a role in facilitating/regulating mitochondrial fatty acid oxidation. PLIN3 and PLIN5 may be working together on the lipid droplet and mitochondria during contraction-induced lipolysis.
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Affiliation(s)
- Sofhia V Ramos
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Rebecca E K MacPherson
- Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Patrick C Turnbull
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Kirsten N Bott
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Paul LeBlanc
- Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Department of Health Science, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Wendy E Ward
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Department of Health Science, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Sandra J Peters
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
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29
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Mason RR, Meex RCR, Russell AP, Canny BJ, Watt MJ. Cellular localization and associations of the major lipolytic proteins in human skeletal muscle at rest and during exercise. PLoS One 2014; 9:e103062. [PMID: 25054327 PMCID: PMC4108417 DOI: 10.1371/journal.pone.0103062] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/27/2014] [Indexed: 11/18/2022] Open
Abstract
Lipolysis involves the sequential breakdown of fatty acids from triacylglycerol and is increased during energy stress such as exercise. Adipose triglyceride lipase (ATGL) is a key regulator of skeletal muscle lipolysis and perilipin (PLIN) 5 is postulated to be an important regulator of ATGL action of muscle lipolysis. Hence, we hypothesized that non-genomic regulation such as cellular localization and the interaction of these key proteins modulate muscle lipolysis during exercise. PLIN5, ATGL and CGI-58 were highly (>60%) colocated with Oil Red O (ORO) stained lipid droplets. PLIN5 was significantly colocated with ATGL, mitochondria and CGI-58, indicating a close association between the key lipolytic effectors in resting skeletal muscle. The colocation of the lipolytic proteins, their independent association with ORO and the PLIN5/ORO colocation were not altered after 60 min of moderate intensity exercise. Further experiments in cultured human myocytes showed that PLIN5 colocation with ORO or mitochondria is unaffected by pharmacological activation of lipolytic pathways. Together, these data suggest that the major lipolytic proteins are highly expressed at the lipid droplet and colocate in resting skeletal muscle, that their localization and interactions appear to remain unchanged during prolonged exercise, and, accordingly, that other post-translational mechanisms are likely regulators of skeletal muscle lipolysis.
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Affiliation(s)
- Rachael R. Mason
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Ruth C. R. Meex
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Aaron P. Russell
- Centre of Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
| | - Benedict J. Canny
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Matthew J. Watt
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
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