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Zhu X, Zeng C, Yu B. White adipose tissue in metabolic associated fatty liver disease. Clin Res Hepatol Gastroenterol 2024; 48:102336. [PMID: 38604293 DOI: 10.1016/j.clinre.2024.102336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/28/2024] [Accepted: 04/05/2024] [Indexed: 04/13/2024]
Abstract
BACKGROUND Metabolic associated fatty liver disease (MAFLD) is a prevalent chronic liver condition globally, currently lacking universally recognized therapeutic drugs, thereby increasing the risk of cirrhosis and hepatocellular carcinoma. Research has reported an association between white adipose tissue and MAFLD. SCOPE OF REVIEW White adipose tissue (WAT) is involved in lipid metabolism and can contribute to the progression of MAFLD by mediating insulin resistance, inflammation, exosomes, autophagy, and other processes. This review aims to elucidate the mechanisms through which WAT plays a role in the development of MAFLD. MAJOR CONCLUSIONS WAT participates in the occurrence and progression of MAFLD by mediating insulin resistance, inflammation, autophagy, and exosome secretion. Fibrosis and restricted expansion of adipose tissue can lead to the release of more free fatty acids (FFA), exacerbating the progression of MAFLD. WAT-secreted TNF-α and IL-1β, through the promotion of JNK/JKK/p38MAPK expression, interfere with insulin receptor serine and tyrosine phosphorylation, worsening insulin resistance. Adiponectin, by inhibiting the TLR-4-NF-κB pathway and suppressing M2 to M1 transformation, further inhibits the secretion of IL-6, IL-1β, and TNF-α, improving insulin resistance in MAFLD patients. Various gene expressions within WAT, such as MBPAT7, Nrf2, and Ube4A, can ameliorate insulin resistance in MAFLD patients. Autophagy-related gene Atg7 promotes the expression of fibrosis-related genes, worsening MAFLD. Non-pharmacological treatments, including diabetes-related medications and exercise, can improve MAFLD.
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Affiliation(s)
- Xiaoqin Zhu
- Department of Gastroenterology, Renmin Hospital of Wuhan University, No. 99 Zhang Zhidong Road, Wuhan, Hubei, 430000, PR China
| | - Chuanfei Zeng
- Department of Gastroenterology, Renmin Hospital of Wuhan University, No. 99 Zhang Zhidong Road, Wuhan, Hubei, 430000, PR China
| | - Baoping Yu
- Department of Gastroenterology, Renmin Hospital of Wuhan University, No. 99 Zhang Zhidong Road, Wuhan, Hubei, 430000, PR China.
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2
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Wang Y, Ye L. The Afferent Function of Adipose Innervation. Diabetes 2024; 73:348-354. [PMID: 38377447 PMCID: PMC10882147 DOI: 10.2337/dbi23-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 12/18/2023] [Indexed: 02/22/2024]
Abstract
Adipose tissue innervation is critical for regulating metabolic and energy homeostasis. While the sympathetic efferent innervation of fat is well characterized, the role of sensory or afferent innervation remains less explored. This article reviews previous work on adipose innervation and recent advances in the study of sensory innervation of adipose tissues. We discuss key open questions, including the physiological implications of adipose afferents in homeostasis as well as potential cross talk with sympathetic neurons, the immune system, and hormonal pathways. We also outline the general technical challenges of studying dorsal root ganglia innervating fat, along with emerging technologies that may overcome these barriers. Finally, we highlight areas for further research to deepen our understanding of the afferent function of adipose innervation.
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Affiliation(s)
- Yu Wang
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA
| | - Li Ye
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA
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Mishra G, Townsend KL. Sensory nerve and neuropeptide diversity in adipose tissues. Mol Cells 2024; 47:100030. [PMID: 38364960 PMCID: PMC10960112 DOI: 10.1016/j.mocell.2024.100030] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/06/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
Both brown and white adipose tissues (BAT/WAT) are innervated by the peripheral nervous system, including efferent sympathetic nerves that communicate from the brain/central nervous system out to the tissue, and afferent sensory nerves that communicate from the tissue back to the brain and locally release neuropeptides to the tissue upon stimulation. This bidirectional neural communication is important for energy balance and metabolic control, as well as maintaining adipose tissue health through processes like browning (development of metabolically healthy brown adipocytes in WAT), thermogenesis, lipolysis, and adipogenesis. Decades of sensory nerve denervation studies have demonstrated the particular importance of adipose sensory nerves for brown adipose tissue and WAT functions, but far less is known about the tissue's sensory innervation compared to the better-studied sympathetic nerves and their neurotransmitter norepinephrine. In this review, we cover what is known and not yet known about sensory nerve activities in adipose, focusing on their effector neuropeptide actions in the tissue.
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Affiliation(s)
- Gargi Mishra
- Department of Neurological Surgery, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Kristy L Townsend
- Department of Neurological Surgery, College of Medicine, The Ohio State University, Columbus, OH, USA.
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Lorsignol A, Rabiller L, Labit E, Casteilla L, Pénicaud L. The nervous system and adipose tissues: a tale of dialogues. Am J Physiol Endocrinol Metab 2023; 325:E480-E490. [PMID: 37729026 DOI: 10.1152/ajpendo.00115.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/16/2023] [Accepted: 09/18/2023] [Indexed: 09/22/2023]
Abstract
White, beige, and brown adipose tissues play a crucial role in maintaining energy homeostasis. Due to the heterogeneous and diffuse nature of fat pads, this balance requires a fine and coordinated control of many actors and therefore permanent dialogues between these tissues and the central nervous system. For about two decades, many studies have been devoted to describe the neuro-anatomical and functional complexity involved to ensure this dialogue. Thus, if it is now clearly demonstrated that there is an efferent sympathetic innervation of different fat depots controlling plasticity as well as metabolic functions of the fat pad, the crucial role of sensory innervation capable of detecting local signals informing the central nervous system of the metabolic state of the relevant pads is much more recent. The purpose of this review is to provide the current state of knowledge on this subject.
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Affiliation(s)
- Anne Lorsignol
- RESTORE, CNRS, Inserm, Université de Toulouse, Toulouse, France
| | - Lise Rabiller
- RESTORE, CNRS, Inserm, Université de Toulouse, Toulouse, France
| | - Elodie Labit
- RESTORE, CNRS, Inserm, Université de Toulouse, Toulouse, France
| | - Louis Casteilla
- RESTORE, CNRS, Inserm, Université de Toulouse, Toulouse, France
| | - Luc Pénicaud
- RESTORE, CNRS, Inserm, Université de Toulouse, Toulouse, France
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Cortada M, Levano S, Hall MN, Bodmer D. mTORC2 regulates auditory hair cell structure and function. iScience 2023; 26:107687. [PMID: 37694145 PMCID: PMC10484995 DOI: 10.1016/j.isci.2023.107687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/14/2023] [Accepted: 08/17/2023] [Indexed: 09/12/2023] Open
Abstract
mTOR broadly controls cell growth, but little is known about the role of mTOR complex 2 (mTORC2) in the inner ear. To investigate the role of mTORC2 in sensory hair cells (HCs), we generated HC-specific Rictor knockout (HC-RicKO) mice. HC-RicKO mice exhibited early-onset, progressive, and profound hearing loss. Increased DPOAE thresholds indicated outer HC dysfunction. HCs are lost, but this occurs after hearing loss. Ultrastructural analysis revealed stunted and absent stereocilia in outer HCs. In inner HCs, the number of synapses was significantly decreased and the remaining synapses displayed a disrupted actin cytoskeleton and disorganized Ca2+ channels. Thus, the mTORC2 signaling pathway plays an important role in regulating auditory HC structure and function via regulation of the actin cytoskeleton. These results provide molecular insights on a central regulator of cochlear HCs and thus hearing.
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Affiliation(s)
- Maurizio Cortada
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | - Soledad Levano
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | | | - Daniel Bodmer
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
- Clinic for Otorhinolaryngology, Head and Neck Surgery, University of Basel Hospital, CH-4031 Basel, Switzerland
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Mishra G, Townsend KL. The metabolic and functional roles of sensory nerves in adipose tissues. Nat Metab 2023; 5:1461-1474. [PMID: 37709960 DOI: 10.1038/s42255-023-00868-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 07/18/2023] [Indexed: 09/16/2023]
Abstract
Homeostatic regulation of adipose tissue is critical for the maintenance of energy balance and whole-body metabolism. The peripheral nervous system provides bidirectional neural communication between the brain and adipose tissue, thereby providing homeostatic control. Most research on adipose innervation and nerve functions has been limited to the sympathetic nerves and their neurotransmitter norepinephrine. In recent years, more work has focused on adipose sensory nerves, but the contributions of subsets of sensory nerves to metabolism and the specific roles contributed by sensory neuropeptides are still understudied. Advances in imaging of adipose innervation and newer tissue denervation techniques have confirmed that sensory nerves contribute to the regulation of adipose functions, including lipolysis and browning. Here, we summarize the historical and latest findings on the regulation, function and plasticity of adipose tissue sensory nerves that contribute to metabolically important processes such as lipolysis, vascular control and sympathetic axis cross-talk.
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Affiliation(s)
- Gargi Mishra
- Department of Neurological Surgery, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Kristy L Townsend
- Department of Neurological Surgery, College of Medicine, The Ohio State University, Columbus, OH, USA.
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Sharp ZD, Strong R. Rapamycin, the only drug that has been consistently demonstrated to increase mammalian longevity. An update. Exp Gerontol 2023; 176:112166. [PMID: 37011714 PMCID: PMC10868408 DOI: 10.1016/j.exger.2023.112166] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/05/2023]
Affiliation(s)
- Zelton Dave Sharp
- Department of Molecular Medicine and Institute of Biotechnology, San Antonio, TX, United States of America; Barshop Institute for Longevity and Aging Studies, San Antonio, TX, United States of America; Mays Cancer Center, San Antonio, TX, United States of America.
| | - Randy Strong
- Barshop Institute for Longevity and Aging Studies, San Antonio, TX, United States of America; Department of Pharmacology, UT Health, San Antonio, TX, United States of America; Research Service of the South Texas Veterans Health Care System, San Antonio, TX 78229, United States of America.
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8
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Wang Y, Ye L. Somatosensory innervation of adipose tissues. Physiol Behav 2023; 265:114174. [PMID: 36965573 DOI: 10.1016/j.physbeh.2023.114174] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023]
Abstract
The increasing prevalence of obesity and type 2 diabetes has led to a greater interest in adipose tissue physiology. Adipose tissue is now understood as an organ with endocrine and thermogenic capacities in addition to its role in fat storage. It plays a critical role in systemic metabolism and energy regulation, and its activity is tightly regulated by the nervous system. Fat is now recognized to receive sympathetic innervation, which transmits information from the brain, as well as sensory innervation, which sends information into the brain. The role of sympathetic innervation in adipose tissue has been extensively studied. However, the extent and the functional significance of sensory innervation have long been unclear. Recent studies have started to reveal that sensory neurons robustly innervate adipose tissue and play an important role in regulating fat activity. This brief review will discuss both historical evidence and recent advances, as well as important remaining questions about the sensory innervation of adipose tissue.
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Affiliation(s)
- Yu Wang
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Li Ye
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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9
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Shimobayashi M, Thomas A, Shetty S, Frei IC, Wölnerhanssen BK, Weissenberger D, Vandekeere A, Planque M, Dietz N, Ritz D, Meyer-Gerspach AC, Maier T, Hay N, Peterli R, Fendt SM, Rohner N, Hall MN. Diet-induced loss of adipose hexokinase 2 correlates with hyperglycemia. eLife 2023; 12:85103. [PMID: 36920797 PMCID: PMC10017106 DOI: 10.7554/elife.85103] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/19/2023] [Indexed: 03/16/2023] Open
Abstract
Chronically high blood glucose (hyperglycemia) leads to diabetes and fatty liver disease. Obesity is a major risk factor for hyperglycemia, but the underlying mechanism is unknown. Here, we show that a high-fat diet (HFD) in mice causes early loss of expression of the glycolytic enzyme Hexokinase 2 (HK2) specifically in adipose tissue. Adipose-specific knockout of Hk2 reduced glucose disposal and lipogenesis and enhanced fatty acid release in adipose tissue. In a non-cell-autonomous manner, Hk2 knockout also promoted glucose production in liver. Furthermore, we observed reduced hexokinase activity in adipose tissue of obese and diabetic patients, and identified a loss-of-function mutation in the hk2 gene of naturally hyperglycemic Mexican cavefish. Mechanistically, HFD in mice led to loss of HK2 by inhibiting translation of Hk2 mRNA. Our findings identify adipose HK2 as a critical mediator of local and systemic glucose homeostasis, and suggest that obesity-induced loss of adipose HK2 is an evolutionarily conserved mechanism for the development of selective insulin resistance and thereby hyperglycemia.
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Affiliation(s)
- Mitsugu Shimobayashi
- Biozentrum, University of BaselBaselSwitzerland
- Department of Chronic Diseases and Metabolism, Laboratory of Clinical and Experimental Endocrinology, KU LeuvenLeuvenBelgium
| | | | | | | | | | | | - Anke Vandekeere
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer BiologyLeuvenBelgium
- Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer InstituteLeuvenBelgium
| | - Mélanie Planque
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer BiologyLeuvenBelgium
- Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer InstituteLeuvenBelgium
| | | | - Danilo Ritz
- Biozentrum, University of BaselBaselSwitzerland
| | | | - Timm Maier
- Biozentrum, University of BaselBaselSwitzerland
| | - Nissim Hay
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at ChicagoChicagoUnited States
| | - Ralph Peterli
- Clarunis, Department of Visceral Surgery, University Centre for Gastrointestinal and Liver DiseasesBaselSwitzerland
| | - Sarah-Maria Fendt
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer BiologyLeuvenBelgium
- Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer InstituteLeuvenBelgium
| | - Nicolas Rohner
- Stowers Institute for Medical ResearchKansas CityUnited States
- Department of Cell Biology and Physiology at the University of Kansas School of MedicineKansas CityUnited States
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Li Q, Zeng W. Sensing and acting: Full circle in fat. Cell Metab 2023; 35:9-11. [PMID: 36599305 DOI: 10.1016/j.cmet.2022.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
White adipose tissue (WAT) communicates with the CNS bidirectionally. In recent studies, aided by three-dimensional imaging, Wang et al. and Frei et al. have provided the organ-wide view of the afferent somatosensory network in the inguinal WAT (iWAT) and have further delineated its critical involvement in energy balance.
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Affiliation(s)
- Qingqing Li
- Institute for Immunology and School of Medicine, Tsinghua University, and Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Wenwen Zeng
- Institute for Immunology and School of Medicine, Tsinghua University, and Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China; Beijing Key Laboratory for Immunological Research on Chronic Diseases, Beijing, 100084, China.
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