1
|
Zhang L, Zhou Y, Yang Z, Jiang L, Yan X, Zhu W, Shen Y, Wang B, Li J, Song J. Lipid droplets in central nervous system and functional profiles of brain cells containing lipid droplets in various diseases. J Neuroinflammation 2025; 22:7. [PMID: 39806503 PMCID: PMC11730833 DOI: 10.1186/s12974-025-03334-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2024] [Accepted: 01/02/2025] [Indexed: 01/16/2025] Open
Abstract
Lipid droplets (LDs), serving as the convergence point of energy metabolism and multiple signaling pathways, have garnered increasing attention in recent years. Different cell types within the central nervous system (CNS) can regulate energy metabolism to generate or degrade LDs in response to diverse pathological stimuli. This article provides a comprehensive review on the composition of LDs in CNS, their generation and degradation processes, their interaction mechanisms with mitochondria, the distribution among different cell types, and the roles played by these cells-particularly microglia and astrocytes-in various prevalent neurological disorders. Additionally, we also emphasize the paradoxical role of LDs in post-cerebral ischemia inflammation and explore potential underlying mechanisms, aiming to identify novel therapeutic targets for this disease.
Collapse
Affiliation(s)
- Longxiao Zhang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Yunfei Zhou
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Zhongbo Yang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Liangchao Jiang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Xinyang Yan
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Wenkai Zhu
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Yi Shen
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Bolong Wang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China
| | - Jiaxi Li
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
| | - Jinning Song
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
| |
Collapse
|
2
|
Huang J, Wang J. Selective protein degradation through chaperone‑mediated autophagy: Implications for cellular homeostasis and disease (Review). Mol Med Rep 2025; 31:13. [PMID: 39513615 PMCID: PMC11542157 DOI: 10.3892/mmr.2024.13378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 06/03/2024] [Indexed: 11/15/2024] Open
Abstract
Cells rely on autophagy for the degradation and recycling of damaged proteins and organelles. Chaperone-mediated autophagy (CMA) is a selective process targeting proteins for degradation through the coordinated function of molecular chaperones and the lysosome‑associated membrane protein‑2A receptor (LAMP2A), pivotal in various cellular processes from signal transduction to the modulation of cellular responses under stress. In the present review, the intricate regulatory mechanisms of CMA were elucidated through multiple signaling pathways such as retinoic acid receptor (RAR)α, AMP‑activated protein kinase (AMPK), p38‑TEEB‑NLRP3, calcium signaling‑NFAT and PI3K/AKT, thereby expanding the current understanding of CMA regulation. A comprehensive exploration of CMA's versatile roles in cellular physiology were further provided, including its involvement in maintaining protein homeostasis, regulating ferroptosis, modulating metabolic diversity and influencing cell cycle and proliferation. Additionally, the impact of CMA on disease progression and therapeutic outcomes were highlighted, encompassing neurodegenerative disorders, cancer and various organ‑specific diseases. Therapeutic strategies targeting CMA, such as drug development and gene therapy were also proposed, providing valuable directions for future clinical research. By integrating recent research findings, the present review aimed to enhance the current understanding of cellular homeostasis processes and emphasize the potential of targeting CMA in therapeutic strategies for diseases marked by CMA dysfunction.
Collapse
Affiliation(s)
- Jiahui Huang
- Collaborative Innovation Center for Chinese Medicine and Respiratory Diseases Co-Constructed by Henan Province and Education Ministry of People's Republic of China, Henan University of Chinese Medicine, Zhengzhou, Henan 450046, P.R. China
- College of Traditional Chinese Medicine, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan 450046, P.R. China
| | - Jiazhen Wang
- Collaborative Innovation Center for Chinese Medicine and Respiratory Diseases Co-Constructed by Henan Province and Education Ministry of People's Republic of China, Henan University of Chinese Medicine, Zhengzhou, Henan 450046, P.R. China
- Academy of Chinese Medicine Science, Henan University of Chinese Medicine, Zhengzhou, Henan 450046, P.R. China
| |
Collapse
|
3
|
Fader Kaiser CM, Romano PS, Vanrell MC, Pocognoni CA, Jacob J, Caruso B, Delgui LR. Biogenesis and Breakdown of Lipid Droplets in Pathological Conditions. Front Cell Dev Biol 2022; 9:826248. [PMID: 35198567 PMCID: PMC8860030 DOI: 10.3389/fcell.2021.826248] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/22/2021] [Indexed: 12/17/2022] Open
Abstract
Lipid droplets (LD) have long been considered as mere fat drops; however, LD have lately been revealed to be ubiquitous, dynamic and to be present in diverse organelles in which they have a wide range of key functions. Although incompletely understood, the biogenesis of eukaryotic LD initiates with the synthesis of neutral lipids (NL) by enzymes located in the endoplasmic reticulum (ER). The accumulation of NL leads to their segregation into nanometric nuclei which then grow into lenses between the ER leaflets as they are further filled with NL. The lipid composition and interfacial tensions of both ER and the lenses modulate their shape which, together with specific ER proteins, determine the proneness of LD to bud from the ER toward the cytoplasm. The most important function of LD is the buffering of energy. But far beyond this, LD are actively integrated into physiological processes, such as lipid metabolism, control of protein homeostasis, sequestration of toxic lipid metabolic intermediates, protection from stress, and proliferation of tumours. Besides, LD may serve as platforms for pathogen replication and defense. To accomplish these functions, from biogenesis to breakdown, eukaryotic LD have developed mechanisms to travel within the cytoplasm and to establish contact with other organelles. When nutrient deprivation occurs, LD undergo breakdown (lipolysis), which begins with the LD-associated members of the perilipins family PLIN2 and PLIN3 chaperone-mediated autophagy degradation (CMA), a specific type of autophagy that selectively degrades a subset of cytosolic proteins in lysosomes. Indeed, PLINs CMA degradation is a prerequisite for further true lipolysis, which occurs via cytosolic lipases or by lysosome luminal lipases when autophagosomes engulf portions of LD and target them to lysosomes. LD play a crucial role in several pathophysiological processes. Increased accumulation of LD in non-adipose cells is commonly observed in numerous infectious diseases caused by intracellular pathogens including viral, bacterial, and parasite infections, and is gradually recognized as a prominent characteristic in a variety of cancers. This review discusses current evidence related to the modulation of LD biogenesis and breakdown caused by intracellular pathogens and cancer.
Collapse
Affiliation(s)
- Claudio M Fader Kaiser
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Patricia S Romano
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - M Cristina Vanrell
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Cristian A Pocognoni
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Julieta Jacob
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Benjamín Caruso
- Instituto de Investigaciones Biologicas y Tecnologicas, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Cordoba, Cordoba, Argentina
| | - Laura R Delgui
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| |
Collapse
|
4
|
Liao PC, Yang EJ, Borgman T, Boldogh IR, Sing CN, Swayne TC, Pon LA. Touch and Go: Membrane Contact Sites Between Lipid Droplets and Other Organelles. Front Cell Dev Biol 2022; 10:852021. [PMID: 35281095 PMCID: PMC8908909 DOI: 10.3389/fcell.2022.852021] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 02/03/2022] [Indexed: 12/26/2022] Open
Abstract
Lipid droplets (LDs) have emerged not just as storage sites for lipids but as central regulators of metabolism and organelle quality control. These critical functions are achieved, in part, at membrane contact sites (MCS) between LDs and other organelles. MCS are sites of transfer of cellular constituents to or from LDs for energy mobilization in response to nutrient limitations, as well as LD biogenesis, expansion and autophagy. Here, we describe recent findings on the mechanisms underlying the formation and function of MCS between LDs and mitochondria, ER and lysosomes/vacuoles and the role of the cytoskeleton in promoting LD MCS through its function in LD movement and distribution in response to environmental cues.
Collapse
Affiliation(s)
- Pin-Chao Liao
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Emily J. Yang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Taylor Borgman
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Istvan R. Boldogh
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, United States
| | - Cierra N. Sing
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Theresa C. Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, United States
| | - Liza A. Pon
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
- *Correspondence: Liza A. Pon,
| |
Collapse
|
5
|
Adipose Triglyceride Lipase in Hepatic Physiology and Pathophysiology. Biomolecules 2021; 12:biom12010057. [PMID: 35053204 PMCID: PMC8773762 DOI: 10.3390/biom12010057] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/28/2021] [Accepted: 12/28/2021] [Indexed: 12/25/2022] Open
Abstract
The liver is extremely active in oxidizing triglycerides (TG) for energy production. An imbalance between TG synthesis and hydrolysis leads to metabolic disorders in the liver, including excessive lipid accumulation, oxidative stress, and ultimately liver damage. Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme that catalyzes the first step of TG breakdown to glycerol and fatty acids. Although its role in controlling lipid homeostasis has been relatively well-studied in the adipose tissue, heart, and skeletal muscle, it remains largely unknown how and to what extent ATGL is regulated in the liver, responds to stimuli and regulators, and mediates disease progression. Therefore, in this review, we describe the current understanding of the structure–function relationship of ATGL, the molecular mechanisms of ATGL regulation at translational and post-translational levels, and—most importantly—its role in lipid and glucose homeostasis in health and disease with a focus on the liver. Advances in understanding the molecular mechanisms underlying hepatic lipid accumulation are crucial to the development of targeted therapies for treating hepatic metabolic disorders.
Collapse
|
6
|
Qiao L, Wang HF, Xiang L, Ma J, Zhu Q, Xu D, Zheng H, Peng JQ, Zhang S, Lu HX, Chen WQ, Zhang Y. Deficient Chaperone-Mediated Autophagy Promotes Lipid Accumulation in Macrophage. J Cardiovasc Transl Res 2021; 14:661-669. [PMID: 32285315 PMCID: PMC8397667 DOI: 10.1007/s12265-020-09986-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/06/2020] [Indexed: 01/22/2023]
Abstract
Chaperone-mediated autophagy (CMA) serves as a critical upstream regulator of lipophagy and lipid metabolism in hepatocyte. However, the role of CMA in lipid metabolism of macrophage, the typical component of atherosclerotic plaque, remains unclear. In our study, LAMP-2A (L2A, a CMA marker) was reduced in macrophages exposed to high dose of oleate, and lipophagy was impaired in advanced atherosclerosis in ApoE (-/-) mice. Primary peritoneal macrophages isolated from macrophage-specific L2A-deficient mice exhibited pronounced intracellular lipid accumulation. Lipid regulatory enzymes, including long-chain-fatty-acid-CoA ligase 1 (ACSL1) and lysosomal acid lipase (LAL), were increased and reduced in L2A-KO macrophage, respectively. Other lipid-related proteins, such as SR-A, SR-B (CD36), ABCA1, or PLIN2, were not associated with increased lipid content in L2A-KO macrophage. In conclusion, deficient CMA promotes lipid accumulation in macrophage probably by regulating enzymes involved in lipid metabolism. CMA may represent a novel therapeutic target to alleviate atherosclerosis by promoting lipid metabolism. Graphical abstract.
Collapse
Affiliation(s)
- Lei Qiao
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
| | - He-Feng Wang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
- Qilu Hospital of Shandong University (Qingdao), No. 758 Hefei Road, Qingdao, 266035, China
| | - Lei Xiang
- Department of Cardiology, Sishui County People's Hospital, Sishui, 273200, Shandong, China
| | - Jing Ma
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
| | - Qiang Zhu
- Department of clinical laboratory, Sishui County People's Hospital, Sishui, 273200, Shandong, China
| | - Dan Xu
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
| | - Hui Zheng
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
| | - Jie-Qiong Peng
- School of Medicine and Life Sciences, University of Jinan-Shandong Academy of Medical Sciences, Jinan, China
| | - Sen Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
- Qilu Hospital of Shandong University (Qingdao), No. 758 Hefei Road, Qingdao, 266035, China
| | - Hui-Xia Lu
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China
| | - Wen-Qiang Chen
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China.
| | - Yun Zhang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Department of Cardiology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, 250012, Jinan, China.
| |
Collapse
|
7
|
Ma SY, Sun KS, Zhang M, Zhou X, Zheng XH, Tian SY, Liu YS, Chen L, Gao X, Ye J, Zhou XM, Wang JB, Han Y. Disruption of Plin5 degradation by CMA causes lipid homeostasis imbalance in NAFLD. Liver Int 2020; 40:2427-2438. [PMID: 32339374 DOI: 10.1111/liv.14492] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 03/26/2020] [Accepted: 04/06/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND & AIMS The pathological hallmark of nonalcoholic fatty liver disease (NAFLD) is an imbalance in hepatic lipid homeostasis, in which lipophagy has been found to play a vital role. However, the underlying molecular mechanisms remain unclear. We investigated the role of chaperone-mediated autophagy (CMA) in the pathogenesis of NAFLD. METHODS CMA activity was evaluated in liver tissues from NAFLD patients and high-fat diet (HFD)-fed mice. Liver-specific LAMP2A-knockout mice and HepG2 cells lacking LAMP2A [L2A(-) cells] were used to investigate the influence of CMA on lipolysis in hepatocytes. The expression of Plin5, a lipid droplet (LD)-related protein, was also evaluated in human and mouse liver tissues and in [L2A(-)] cells. RESULTS Here, we found disrupted CMA function in the livers of NAFLD patients and animal models, displaying obvious reduction of LAMP2A and concurrent with decreased levels of CMA-positive regulators. More LDs and higher serum triglycerides accumulated in liver-specific LAMP2A-knockout mice and L2A(-) cells under high-fat challenge. Meanwhile, deleting LAMP2A hindered LD breakdown but not increased LD formation. In addition, the LD-associated protein Plin5 is a CMA substrate, and its degradation through CMA is required for LD breakdown. CONCLUSIONS We propose that the disruption of CMA-induced Plin5 degradation obstacles LD breakdown, explaining the lipid homeostasis imbalance in NAFLD.
Collapse
Affiliation(s)
- Shuo Y Ma
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Ke S Sun
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Miao Zhang
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Xia Zhou
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Xiao H Zheng
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Si Y Tian
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Yan S Liu
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Ling Chen
- Division of Pathology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Xing Gao
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jing Ye
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Xin M Zhou
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Jing B Wang
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| | - Ying Han
- Division of Hepatology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, National Clinical Research Centre for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
| |
Collapse
|
8
|
Abstract
Lipid droplets (LDs) are now recognized as omnipresent and dynamic subcellular organelles of amazing morphological and functional diversity. Beyond the obvious benefit of having molecules full of chemical energy stored in a dedicated structural entity, LDs may also be viewed as a safe harbor for potentially damaging metabolites. This protective function might in many cases even supersede the relevance of lipid storage for eventual energy gain and membrane biogenesis. Furthermore, the LD surface constitutes a unique membrane environment, creating a platform for hosting specific proteins and thus enabling their interactions. These metabolic hotspots would contribute decisively to compartmentalized metabolism in the cytosol. LDs are also communicating extensively with other subcellular organelles in directing and regulating lipid metabolism. Deciphering the relevance of LD storage and regulation at the organismic level will be essential for the understanding of widespread and serious metabolic complications in humans. Increasing attention is also devoted to pathogens appropriating LDs for their own benefit. LD biology is still considered an emerging research area in rapid and vibrant development, attracting scientists from all disciplines of the life sciences and beyond, which is mirrored by the accompanying review collection. Here, we present our personal views on areas we believe are especially exciting and hold great potential for future developments. Particularly, we address issues relating to LD biogenesis and heterogeneity, required technological advances, and the complexity of human physiology.
Collapse
|
9
|
Thomes PG, Rasineni K, Yang L, Donohue TM, Kubik JL, McNiven MA, Casey CA. Ethanol withdrawal mitigates fatty liver by normalizing lipid catabolism. Am J Physiol Gastrointest Liver Physiol 2019; 316:G509-G518. [PMID: 30714813 PMCID: PMC6957361 DOI: 10.1152/ajpgi.00376.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We are investigating the changes in hepatic lipid catabolism that contribute to alcohol-induced fatty liver. Following chronic ethanol (EtOH) exposure, abstinence from alcohol resolves steatosis. Here, we investigated the hepatocellular events that lead to this resolution by quantifying specific catabolic parameters that returned to control levels after EtOH was withdrawn. We hypothesized that, after its chronic consumption, EtOH withdrawal reactivates lipid catabolic processes that restore lipostasis. Male Wistar rats were fed control and EtOH liquid diets for 6 wk. Randomly chosen EtOH-fed rats were then fed control diet for 7 days. Liver triglycerides (TG), lipid peroxides, key markers of fatty acid (FA) metabolism, lipophagy, and autophagy were quantified. Compared with controls, EtOH-fed rats had higher hepatic triglycerides, lipid peroxides, and serum free fatty acids (FFA). The latter findings were associated with higher levels of FA transporters (FATP 2, 4, and 5) but lower quantities of peroxisome proliferator-activated receptor-α (PPAR-α), which governs FA oxidation. EtOH-fed animals also had lower nuclear levels of the autophagy-regulating transcription factor EB (TFEB), associated with lower hepatic lipophagy and autophagy. After EtOH-fed rats were refed control diet for 7 days, their serum FFA levels and those of FATPs fell to control (normal) levels, whereas PPAR-α levels rose to normal. Hepatic TG and malondialdehyde levels in EtOH-withdrawn rats declined to near control levels. EtOH withdrawal restored nuclear TFEB content, hepatic lipophagy, and autophagy activity to control levels. EtOH withdrawal reversed aberrant FA metabolism and restored lysosomal function to promote resolution of alcohol-induced fatty liver. NEW & NOTEWORTHY Here, using an animal model, we show mechanisms of reversal of fatty liver and injury following EtOH withdrawal. Our data indicate that reactivation of autophagy and lysosome function through the restoration of transcription factor EB contribute to reversal of fatty liver and injury following EtOH withdrawal.
Collapse
Affiliation(s)
- Paul G. Thomes
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Karuna Rasineni
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Li Yang
- 7Departmentof Internal Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Terrence M. Donohue
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,3Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska,4Pathology and Microbiology; College of Medicine; University of Nebraska Medical Center, Omaha, Nebraska,5The Center for Environmental Toxicology; College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska
| | - Jacy L. Kubik
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Mark A. McNiven
- 6Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Carol A. Casey
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,3Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| |
Collapse
|
10
|
Abstract
SummaryLipid droplets (LDs) are the main energy resource for porcine preimplantation embryonic development. PLIN3 has been implicated in LD formation and regulation. Therefore, this study aimed to detect the dynamic pattern of PLIN3 in pig oocytes and cumulus cells (CC) during in vitro maturation (IVM), and to determine the relationship between PLIN3 and LD content. IVM with cumulus-enclosed oocytes (CEO), cumulus-denuded oocytes (DO) and the CCs denuded from the corresponding oocytes (DCC) was performed in porcine follicular fluid (PFF) or PFF-free optimized medium. DO and the DCC were cultured together under the same conditions as described above, while the DO was named DTO and the DCC was named DTCC in this group. Firstly, our results revealed LDs distributed widely in oocytes and CC, while the PLIN3 protein coated these LDs and spread out ubiquitously in the cytoplasm. Secondly, not only the mRNA level but also at protein level of PLIN3 in immature naked oocytes (IO) was higher than that in matured CEO, DO and DTO. Although PLIN3 was expressed at lower levels in CC from immature oocytes (ICC), the protein level of PLIN3 was comparably higher in the ECC and DCC groups. The triglyceride (TG) content in CEO and DO was significantly less abundant compared with that in IO. Therefore, our results indicated that co-culturing of oocytes and CC might affect PLIN3 expression levels in CC but not in oocytes. Lipid accumulation in pig oocytes during maturation might be affected by PLIN3 cross-talk between oocytes and CC.
Collapse
|
11
|
Friesen M, Cowan CA. FPLD2 LMNA mutation R482W dysregulates iPSC-derived adipocyte function and lipid metabolism. Biochem Biophys Res Commun 2017; 495:254-260. [PMID: 29108996 DOI: 10.1016/j.bbrc.2017.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 11/02/2017] [Indexed: 01/05/2023]
Abstract
Lipodystrophies are disorders that directly affect lipid metabolism and storage. Familial partial lipodystrophy type 2 (FPLD2) is caused by an autosomal dominant mutation in the LMNA gene. FPLD2 is characterized by abnormal adipose tissue distribution. This leads to metabolic deficiencies, such as insulin-resistant diabetes mellitus and hypertriglyceridemia. Here we have derived iPSC lines from two individuals diagnosed with FPLD2, and differentiated these cells into adipocytes. Adipogenesis and certain adipocyte functions are impaired in FPLD2-adipocytes. Consistent with the lipodystrophic phenotype, FPLD2-adipocytes appear to accumulate markers of autophagy and catabolize triglycerides at higher levels than control adipocytes. These data are suggestive of a mechanism causing the lack of adipose tissue in FPLD2 patients.
Collapse
Affiliation(s)
- Max Friesen
- Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA; Department of Anatomy and Embryology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands.
| | - Chad A Cowan
- Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
| |
Collapse
|
12
|
Laiglesia LM, Lorente-Cebrián S, López-Yoldi M, Lanas R, Sáinz N, Martínez JA, Moreno-Aliaga MJ. Maresin 1 inhibits TNF-alpha-induced lipolysis and autophagy in 3T3-L1 adipocytes. J Cell Physiol 2017; 233:2238-2246. [PMID: 28703289 DOI: 10.1002/jcp.26096] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 07/11/2017] [Indexed: 12/30/2022]
Abstract
Obesity is associated with high levels of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), which promotes inflammation in adipose tissue. The omega-3 PUFAs, and their derived lipid mediators, such as Maresin 1 (MaR1) have anti-inflammatory effects on adipose tissue. This study aimed to analyze if MaR1 may counteract alterations induced by TNF-α on lipolysis and autophagy in mature 3T3-L1 adipocytes. Our data revealed that MaR1 (1-100 nM) inhibited the TNF-α-induced glycerol release after 48 hr, which may be related to MaR1 ability of preventing the decrease in lipid droplet-coating protein perilipin and G0/G1 Switch 2 protein expression. MaR1 also reversed the decrease in total hormone sensitive lipase (total HSL), and the ratio of phosphoHSL at Ser-565/total HSL, while preventing the increased ratio of phosphoHSL at Ser-660/total HSL and phosphorylation of extracellular signal-regulated kinase 1/2 induced by TNF-α. Moreover, MaR1 counteracted the cytokine-induced decrease of p62 protein, a key autophagy indicator, and also prevented the induction of LC3II/LC3I, an important autophagosome formation marker. Current data suggest that MaR1 may ameliorate TNF-α-induced alterations on lipolysis and autophagy in adipocytes. This may also contribute to the beneficial actions of MaR1 on adipose tissue and insulin sensitivity in obesity.
Collapse
Affiliation(s)
- Laura M Laiglesia
- Department Nutrition Food Science Physiology, University of Navarra, Pamplona, Spain.,Centre for Nutrition Research, University of Navarra, Pamplona, Spain
| | - Silvia Lorente-Cebrián
- Department Nutrition Food Science Physiology, University of Navarra, Pamplona, Spain.,Centre for Nutrition Research, University of Navarra, Pamplona, Spain.,Navarra Institute for Health Research (IdiSNA), Pamplona, Spain
| | - Miguel López-Yoldi
- Department Nutrition Food Science Physiology, University of Navarra, Pamplona, Spain.,Centre for Nutrition Research, University of Navarra, Pamplona, Spain
| | - Raquel Lanas
- Department Nutrition Food Science Physiology, University of Navarra, Pamplona, Spain
| | - Neira Sáinz
- Centre for Nutrition Research, University of Navarra, Pamplona, Spain
| | - Jose Alfredo Martínez
- Department Nutrition Food Science Physiology, University of Navarra, Pamplona, Spain.,Centre for Nutrition Research, University of Navarra, Pamplona, Spain.,Navarra Institute for Health Research (IdiSNA), Pamplona, Spain.,CIBERobn, Physiopathology of Obesity and Nutrition, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Maria J Moreno-Aliaga
- Department Nutrition Food Science Physiology, University of Navarra, Pamplona, Spain.,Centre for Nutrition Research, University of Navarra, Pamplona, Spain.,Navarra Institute for Health Research (IdiSNA), Pamplona, Spain.,CIBERobn, Physiopathology of Obesity and Nutrition, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| |
Collapse
|
13
|
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: 188] [Impact Index Per Article: 23.5] [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.
Collapse
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;
| |
Collapse
|
14
|
Roy D, Mondal S, Khurana A, Jung DB, Hoffmann R, He X, Kalogera E, Dierks T, Hammond E, Dredge K, Shridhar V. Loss of HSulf-1: The Missing Link between Autophagy and Lipid Droplets in Ovarian Cancer. Sci Rep 2017; 7:41977. [PMID: 28169314 PMCID: PMC5294412 DOI: 10.1038/srep41977] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 12/28/2016] [Indexed: 12/13/2022] Open
Abstract
Defective autophagy and deranged metabolic pathways are common in cancer; pharmacologic targeting of these two pathways could provide a viable therapeutic option. However, how these pathways are regulated by limited availability of growth factors is still unknown. Our study shows that HSulf-1 (endosulfatase), a known tumor suppressor which attenuates heparin sulfate binding growth factor signaling, also regulates interplay between autophagy and lipogenesis. Silencing of HSulf-1 in OV202 and TOV2223 cells (ovarian cancer cell lines) resulted in increased lipid droplets (LDs), reduced autophagic vacuoles (AVs) and less LC3B puncta. In contrast, HSulf-1 proficient cells exhibit more AVs and reduced LDs. Increased LDs in HSulf-1 depleted cells was associated with increased ERK mediated cPLA2S505 phosphorylation. Conversely, HSulf-1 expression in SKOV3 cells reduced the number of LDs and increased the number of AVs compared to vector controls. Furthermore, pharmacological (AACOCF3) and ShRNA mediated downregulation of cPLA2 resulted in reduced LDs, and increased autophagy. Finally, in vivo experiment using OV202 Sh1 derived xenograft show that AACOCF3 treatment effectively attenuated tumor growth and LD biogenesis. Collectively, these results show a reciprocal regulation of autophagy and lipid biogenesis by HSulf-1 in ovarian cancer.
Collapse
Affiliation(s)
- Debarshi Roy
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| | - Susmita Mondal
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| | - Ashwani Khurana
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| | - Deok-Beom Jung
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| | - Robert Hoffmann
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| | - Xiaoping He
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| | | | - Thomas Dierks
- Department of Chemistry, Biochemistry I, Bielefeld University, Bielefeld, Germany
| | | | - Keith Dredge
- Zucero Therapeutics. Brisbane, Queensland, Australia
| | - Viji Shridhar
- Department of Experimental Pathology, Mayo Clinic, Rochester, MN, USA
| |
Collapse
|
15
|
The size matters: regulation of lipid storage by lipid droplet dynamics. SCIENCE CHINA-LIFE SCIENCES 2016; 60:46-56. [PMID: 27981432 DOI: 10.1007/s11427-016-0322-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 10/28/2016] [Indexed: 12/14/2022]
Abstract
Adequate energy storage is essential for sustaining healthy life. Lipid droplet (LD) is the subcellular organelle that stores energy in the form of neutral lipids and releases fatty acids under energy deficient conditions. Energy storage capacity of LDs is primarily dependent on the sizes of LDs. Enlargement and growth of LDs is controlled by two molecular pathways: neutral lipid synthesis and atypical LD fusion. Shrinkage of LDs is mediated by the degradation of neutral lipids under energy demanding conditions and is controlled by neutral cytosolic lipases and lysosomal acidic lipases. In this review, we summarize recent progress regarding the regulatory pathways and molecular mechanisms that control the sizes and the energy storage capacity of LDs.
Collapse
|
16
|
Fitzgibbons TP, Czech MP. Emerging evidence for beneficial macrophage functions in atherosclerosis and obesity-induced insulin resistance. J Mol Med (Berl) 2016; 94:267-75. [PMID: 26847458 PMCID: PMC4803808 DOI: 10.1007/s00109-016-1385-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 01/14/2023]
Abstract
The discovery that obesity promotes macrophage accumulation in visceral fat led to the emergence of a new field of inquiry termed "immunometabolism". This broad field of study was founded on the premise that inflammation and the corresponding increase in macrophage number and activity was a pathologic feature of metabolic diseases. There is abundant data in both animal and human studies that supports this assertation. Established adverse effects of inflammation in visceral fat include decreased glucose and fatty acid uptake, inhibition of insulin signaling, and ectopic triglyceride accumulation. Likewise, in the atherosclerotic plaque, macrophage accumulation and activation results in plaque expansion and destabilization. Despite these facts, there is an accumulating body of evidence that macrophages also have beneficial functions in both atherosclerosis and visceral obesity. Potentially beneficial functions that are common to these different contexts include the regulation of efferocytosis, lipid buffering, and anti-inflammatory effects. Autophagy, the process by which cytoplasmic contents are delivered to the lysosome for degradation, is integral to many of these protective biologic functions. The macrophage utilizes autophagy as a molecular tool to maintain tissue integrity and homeostasis at baseline (e.g., bone growth) and in the face of ongoing metabolic insults (e.g., fasting, hypercholesterolemia, obesity). Herein, we highlight recent evidence demonstrating that abrogation of certain macrophage functions, in particular autophagy, exacerbates both atherosclerosis and obesity-induced insulin resistance. Insulin signaling through mammalian target of rapamycin (mTOR) is a crucial regulatory node that links nutrient availability to macrophage autophagic flux. A more precise understanding of the metabolic substrates and triggers for macrophage autophagy may allow therapeutic manipulation of this pathway. These observations underscore the complexity of the field "immunometabolism", validate its importance, and raise many fascinating and important questions for future study.
Collapse
Affiliation(s)
- Timothy P Fitzgibbons
- Cardiovascular Division, Department of Medicine, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA, 01655, USA.
| | - Michael P Czech
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| |
Collapse
|
17
|
Tasset I, Cuervo AM. Role of chaperone-mediated autophagy in metabolism. FEBS J 2016; 283:2403-13. [PMID: 26854402 DOI: 10.1111/febs.13677] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 01/27/2016] [Accepted: 02/04/2016] [Indexed: 12/20/2022]
Abstract
Different types of autophagy coexist in most mammalian cells, and each of them fulfills very specific tasks in intracellular degradation. Some of these autophagic pathways contribute to cellular metabolism by directly hydrolyzing intracellular lipid stores and glycogen. Chaperone-mediated autophagy (CMA), in contrast, is a selective form of autophagy that can only target proteins for lysosomal degradation. Consequently, it was expected that the only possible contribution of this pathway to cellular metabolism would be by providing free amino acids resulting from protein breakdown. However, recent studies have demonstrated that disturbance in CMA leads to important alterations in glucose and lipid metabolism and in overall organism energetics. Here, we describe the unique mechanisms by which CMA contributes to the regulation of cellular metabolism and discuss the possible implications of these previously unknown functions of CMA for the pathogenesis of common metabolic diseases.
Collapse
Affiliation(s)
- Inmaculada Tasset
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY, USA
| |
Collapse
|
18
|
Morigny P, Houssier M, Mouisel E, Langin D. Adipocyte lipolysis and insulin resistance. Biochimie 2015; 125:259-66. [PMID: 26542285 DOI: 10.1016/j.biochi.2015.10.024] [Citation(s) in RCA: 318] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/30/2015] [Indexed: 12/15/2022]
Abstract
Obesity-induced insulin resistance is a major risk factor for the development of type 2 diabetes. Basal fat cell lipolysis (i.e., fat cell triacylglycerol breakdown into fatty acids and glycerol in the absence of stimulatory factors) is elevated during obesity and is closely associated with insulin resistance. Inhibition of adipocyte lipolysis may therefore be a promising therapeutic strategy for treating insulin resistance and preventing obesity-associated type 2 diabetes. In this review, we explore the relationship between adipose lipolysis and insulin sensitivity. After providing an overview of the components of fat cell lipolytic machinery, we describe the hypotheses that may support the causality between lipolysis and insulin resistance. Excessive circulating fatty acids may ectopically accumulate in insulin-sensitive tissues and impair insulin action. Increased basal lipolysis may also modify the secretory profile of adipose tissue, influencing whole body insulin sensitivity. Finally, excessive fatty acid release may also worsen adipose tissue inflammation, a well-known parameter contributing to insulin resistance. Partial genetic or pharmacologic inhibition of fat cell lipases in mice as well as short term clinical trials using antilipolytic drugs in humans support the benefit of fat cell lipolysis inhibition on systemic insulin sensitivity and glucose metabolism, which occurs without an increase of fat mass. Modulation of fatty acid fluxes and, putatively, of fat cell secretory pattern may explain the amelioration of insulin sensitivity whereas changes in adipose tissue immune response do not seem involved.
Collapse
Affiliation(s)
- Pauline Morigny
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France
| | - Marianne Houssier
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France
| | - Etienne Mouisel
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France
| | - Dominique Langin
- INSERM, UMR1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, UMR1048, Paul Sabatier University, France; Toulouse University Hospitals, Department of Clinical Biochemistry, Toulouse, France.
| |
Collapse
|