1
|
Hu M, Feng X, Liu Q, Liu S, Huang F, Xu H. The ion channels of endomembranes. Physiol Rev 2024; 104:1335-1385. [PMID: 38451235 PMCID: PMC11381013 DOI: 10.1152/physrev.00025.2023] [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: 06/30/2023] [Revised: 02/20/2024] [Accepted: 02/25/2024] [Indexed: 03/08/2024] Open
Abstract
The endomembrane system consists of organellar membranes in the biosynthetic pathway [endoplasmic reticulum (ER), Golgi apparatus, and secretory vesicles] as well as those in the degradative pathway (early endosomes, macropinosomes, phagosomes, autophagosomes, late endosomes, and lysosomes). These endomembrane organelles/vesicles work together to synthesize, modify, package, transport, and degrade proteins, carbohydrates, and lipids, regulating the balance between cellular anabolism and catabolism. Large ion concentration gradients exist across endomembranes: Ca2+ gradients for most endomembrane organelles and H+ gradients for the acidic compartments. Ion (Na+, K+, H+, Ca2+, and Cl-) channels on the organellar membranes control ion flux in response to cellular cues, allowing rapid informational exchange between the cytosol and organelle lumen. Recent advances in organelle proteomics, organellar electrophysiology, and luminal and juxtaorganellar ion imaging have led to molecular identification and functional characterization of about two dozen endomembrane ion channels. For example, whereas IP3R1-3 channels mediate Ca2+ release from the ER in response to neurotransmitter and hormone stimulation, TRPML1-3 and TMEM175 channels mediate lysosomal Ca2+ and H+ release, respectively, in response to nutritional and trafficking cues. This review aims to summarize the current understanding of these endomembrane channels, with a focus on their subcellular localizations, ion permeation properties, gating mechanisms, cell biological functions, and disease relevance.
Collapse
Affiliation(s)
- Meiqin Hu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Xinghua Feng
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Qiang Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Siyu Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Fangqian Huang
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Haoxing Xu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States
| |
Collapse
|
2
|
Regulation of yak longissimus lumborum energy metabolism and tenderness by the AMPK/SIRT1 signaling pathways during postmortem storage. PLoS One 2022; 17:e0277410. [PMID: 36441689 PMCID: PMC9704559 DOI: 10.1371/journal.pone.0277410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 10/26/2022] [Indexed: 11/29/2022] Open
Abstract
AMPK can activate nicotinamide phosphoribosyltransferase (NAMPT), increasing the ratio of oxidized nicotinamide adenine dinucleotide (NAD+)/reduced nicotinamide adenine dinucleotide (NADH) ratio, leading to the activation of the energy receptor SIRT1. This pathway is known as the AMPK/SIRT1 signaling pathway. SIRT1 deacetylates and activate LKB1, which is activated by phosphorylation of AMPK (Thr172) and inhibited by phosphorylase-mediated dephosphorylation of AMPK. At the same time, increased AMP/ATP and NAD+/NADH ratios lead to the activation of AMPK and SIRT1. SIRT1 and AMPK can activate each other forming a positive feedback loop, which can strengthen catabolism and weaken anabolism thus maintaining energy homeostasis of energy metabolism. At present, there has been no systematic study on AMPK-associated signaling cascades in stored yak meat and details of the AMPK/SIRT1 signaling under these conditions are not known. In this study, NAD+, NADH were added to yak longissimus thoracic muscles to study AMPK pathway regulation by AMPK/SIRT1 signaling. NAD+ significantly increased the activity of AMPK and glycolysis during postmortem maturation, increased the rate of energy metabolism, and increased the expression of AMPK protein, indicating that NAD+ increased energy metabolism in the stored muscle by promoting AMPK activity. NADH treatment inhibited both AMPK activation and glycolysis, together with increasing the pH in the muscle. The results showed that SIRT1 activation elevated the activity of AMPK, leading to its phosphorylation and the activation of glycolysis. Thus, AMPK activity was found to increase in yak meat as an adaptation to hypoxic conditions. This allows more effective regulation of energy production and improves the tenderness of the meat.
Collapse
|
3
|
Xia Y, Wang S, Song C, Luo R. Spatiotemporal feedforward between PKM2 tetramers and mTORC1 prompts mTORC1 activation. Phys Biol 2022; 19. [PMID: 35613602 DOI: 10.1088/1478-3975/ac7372] [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: 03/01/2022] [Accepted: 05/25/2022] [Indexed: 11/11/2022]
Abstract
Most mammalian cells couple glucose availability to anabolic processes via the mTORC1 pathway. However, the mechanism by which fluctuations in glucose availability are rapidly translated into mTORC1 signals remains elusive. Here, we show that cells rapidly respond to changes in glucose availability through the spatial coupling of mTORC1 and tetramers of the key glycolytic enzyme pyruvate kinase M2 (PKM2) on lysosomal surfaces in the late G1/S phases. The lysosomal localization of PKM2 tetramers enables rapid increases in local ATP concentrations around lysosomes to activate mTORC1, while bypassing the need to elevate global ATP levels in the entire cell. In essence, this spatial coupling establishes a feedforward loop to enable mTORC1 to rapidly sense and respond to changes in glucose availability. We further demonstrate that this mechanism ensures robust cell proliferation upon fluctuating glucose availability. Thus, we present mechanistic insights into the rapid response of the mTORC1 pathway to changes in glucose availability. The underlying mechanism may be applicable to the control of other cellular processes.
Collapse
Affiliation(s)
- Yu Xia
- Fudan University, Rm A601# Life Science Building Fudan University, Yangpu, Shanghai, , Shanghai, 200433, CHINA
| | - ShuMing Wang
- Fudan University, Rm A608# Life Science Building, Fudan University, Yangpu, Shanghai, Shanghai, Shanghai, 200433, CHINA
| | - Chunbo Song
- Fudan University, #Rm 519# Life Science Building, Fudan University, Shanghai, Shanghai, 200433, CHINA
| | - Ruoyu Luo
- School of Life Science, Fudan University, 601# Rm, Building of School of Life Science, 2005#,Songhu Rd, Shanghai, Shanghai, 200433, CHINA
| |
Collapse
|
4
|
Conde-Dusman MJ, Dey PN, Elía-Zudaire Ó, Rabaneda LG, García-Lira C, Grand T, Briz V, Velasco ER, Andero R, Niñerola S, Barco A, Paoletti P, Wesseling JF, Gardoni F, Tavalin SJ, Perez-Otaño I. Control of protein synthesis and memory by GluN3A-NMDA receptors through inhibition of GIT1/mTORC1 assembly. eLife 2021; 10:e71575. [PMID: 34787081 PMCID: PMC8598234 DOI: 10.7554/elife.71575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 10/13/2021] [Indexed: 12/03/2022] Open
Abstract
De novo protein synthesis is required for synapse modifications underlying stable memory encoding. Yet neurons are highly compartmentalized cells and how protein synthesis can be regulated at the synapse level is unknown. Here, we characterize neuronal signaling complexes formed by the postsynaptic scaffold GIT1, the mechanistic target of rapamycin (mTOR) kinase, and Raptor that couple synaptic stimuli to mTOR-dependent protein synthesis; and identify NMDA receptors containing GluN3A subunits as key negative regulators of GIT1 binding to mTOR. Disruption of GIT1/mTOR complexes by enhancing GluN3A expression or silencing GIT1 inhibits synaptic mTOR activation and restricts the mTOR-dependent translation of specific activity-regulated mRNAs. Conversely, GluN3A removal enables complex formation, potentiates mTOR-dependent protein synthesis, and facilitates the consolidation of associative and spatial memories in mice. The memory enhancement becomes evident with light or spaced training, can be achieved by selectively deleting GluN3A from excitatory neurons during adulthood, and does not compromise other aspects of cognition such as memory flexibility or extinction. Our findings provide mechanistic insight into synaptic translational control and reveal a potentially selective target for cognitive enhancement.
Collapse
Affiliation(s)
- María J Conde-Dusman
- lnstituto de Neurociencias (UMH-CSIC)AlicanteSpain
- Centro de Investigación Médica Aplicada (CIMA), University of NavarraPamplonaSpain
- Centre for Developmental Neurobiology, Institute of Psychiatry, King’s College LondonLondonUnited Kingdom
| | - Partha N Dey
- Centro de Investigación Médica Aplicada (CIMA), University of NavarraPamplonaSpain
- National Eye Institute, National Institutes of HealthBethesdaUnited States
| | | | - Luis G Rabaneda
- lnstituto de Neurociencias (UMH-CSIC)AlicanteSpain
- Centro de Investigación Médica Aplicada (CIMA), University of NavarraPamplonaSpain
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | | | - Teddy Grand
- Institut de Biologie de l’Ecole Normale Supérieure/CNRS/INSERMParisFrance
| | - Victor Briz
- Centro de Biología Molecular Severo Ochoa (UAM-CSIC)MadridSpain
| | - Eric R Velasco
- Institut de Neurociències, Universitat Autònoma de BarcelonaBellaterraSpain
| | - Raül Andero
- Institut de Neurociències, Departament de Psicobiologia i de Metodologia de les Ciències de la Salut, Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de BarcelonaBellaterraSpain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos IIIMadridSpain
- ICREABarcelonaSpain
| | | | - Angel Barco
- lnstituto de Neurociencias (UMH-CSIC)AlicanteSpain
| | - Pierre Paoletti
- Institut de Biologie de l’Ecole Normale Supérieure/CNRS/INSERMParisFrance
| | | | - Fabrizio Gardoni
- Department of Pharmacological and Biomolecular Sciences, University of MilanMilanItaly
| | - Steven J Tavalin
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Science CenterMemphisUnited States
| | - Isabel Perez-Otaño
- lnstituto de Neurociencias (UMH-CSIC)AlicanteSpain
- Centro de Investigación Médica Aplicada (CIMA), University of NavarraPamplonaSpain
| |
Collapse
|
5
|
Xu L, Yang C, Wang J, Li Z, Huang R, Ma H, Ma J, Wang Q, Xiong X. Persistent mTORC1 activation via Depdc5 deletion results in spontaneous hepatocellular carcinoma but does not exacerbate carcinogen- and high-fat diet-induced hepatic carcinogenesis in mice. Biochem Biophys Res Commun 2021; 578:142-149. [PMID: 34562654 DOI: 10.1016/j.bbrc.2021.09.036] [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: 08/22/2021] [Accepted: 09/16/2021] [Indexed: 10/20/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) acts as a central regulator of metabolic pathways that drive cellular growth. Abnormal activation of mTORC1 occurs at high frequency in human and mouse hepatocellular carcinoma (HCC). DEP domain-containing protein 5 (DEPDC5), a component of GATOR1 complex, is a repressor of amino acid-sensing branch of the mTORC1 pathway. In the current study, we found that persistent activation of hepatic mTORC1 signaling caused by Depdc5 ablation was sufficient to induce a pathological program of liver damage, inflammation and fibrosis that triggers spontaneous HCC development. Take advantage of the combinatory treatment with a single dose of diethylnitrosamine (DEN) and chronic feeding with high-fat diet (HFD), we demonstrated that hepatic depdc5 deletion did not aggravate DEN&HFD induced liver tumorigenesis, probably due to its protective effects on diet-induced liver steatosis. In addition, we further showed that chronic rapamycin treatment did not have any apparent tumor-suppressing effects on DEN&HFD treated control mice, whereas it dramatically reduced the tumor burden in mice with hepatic Depdc5 ablation. This study provides the novel in vivo evidence for Depdc5 deletion mediated mTORC1 hyperactivation in liver tumorigenesis caused by aging or DEN&HFD treatment. Moreover, our findings also propose that pharmacological inhibition of mTORC1 signaling maybe a promising strategy to treat HCC patients with mutations in DEPDC5 gene.
Collapse
Affiliation(s)
- Lin Xu
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Chenyan Yang
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Jing Wang
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Zun Li
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Rong Huang
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Honghui Ma
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Jie Ma
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Qingzhi Wang
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China
| | - Xiwen Xiong
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China; Xinxiang Key Laboratory of Metabolism and Integrative Physiology, Xinxiang Medical University, Xinxiang, Henan, China.
| |
Collapse
|
6
|
Chen C, Meng Z, Ren H, Zhao N, Shang R, He W, Hao J. The molecular mechanisms supporting the homeostasis and activation of dendritic epidermal T cell and its role in promoting wound healing. BURNS & TRAUMA 2021; 9:tkab009. [PMID: 34212060 PMCID: PMC8240510 DOI: 10.1093/burnst/tkab009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/08/2021] [Indexed: 11/13/2022]
Abstract
The epidermis is the outermost layer of skin and the first barrier against invasion. Dendritic epidermal T cells (DETCs) are a subset of γδ T cells and an important component of the epidermal immune microenvironment. DETCs are involved in skin wound healing, malignancy and autoimmune diseases. DETCs secrete insulin-like growth factor-1 and keratinocyte growth factor for skin homeostasis and re-epithelization and release inflammatory factors to adjust the inflammatory microenvironment of wound healing. Therefore, an understanding of their development, activation and correlative signalling pathways is indispensable for the regulation of DETCs to accelerate wound healing. Our review focuses on the above-mentioned molecular mechanisms to provide a general research framework to regulate and control the function of DETCs.
Collapse
Affiliation(s)
- Cheng Chen
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, the First Affiliated Hospital of Army Medical University (the Third Military Medical University), Chongqing Key Laboratory for Disease Proteomics, Chongqing, 400038, China
| | - Ziyu Meng
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Tianjin Medical University Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, 300134, China
| | - He Ren
- Department of General Surgery, Tianjin Medical University General Hospital, Tianjin Medical University, Tianjin, 300052, China
| | - Na Zhao
- Department of General Surgery, Tianjin Medical University General Hospital, Tianjin Medical University, Tianjin, 300052, China
| | - Ruoyu Shang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, the First Affiliated Hospital of Army Medical University (the Third Military Medical University), Chongqing Key Laboratory for Disease Proteomics, Chongqing, 400038, China
| | - Weifeng He
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, the First Affiliated Hospital of Army Medical University (the Third Military Medical University), Chongqing Key Laboratory for Disease Proteomics, Chongqing, 400038, China
| | - Jianlei Hao
- Zhuhai Institute of Translational Medicine, Zhuhai People's Hospital Affiliated with Jinan University, Jinan University, Zhuhai, 519000, Guangdong, China.,The Biomedical Translational Research Institute, Faculty of Medical Science, Jinan University, Guangzhou, 510632, Guangdong, China
| |
Collapse
|
7
|
The SGLT2 inhibitor empagliflozin negatively regulates IL-17/IL-23 axis-mediated inflammatory responses in T2DM with NAFLD via the AMPK/mTOR/autophagy pathway. Int Immunopharmacol 2021; 94:107492. [PMID: 33647823 DOI: 10.1016/j.intimp.2021.107492] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/28/2021] [Accepted: 02/08/2021] [Indexed: 12/12/2022]
Abstract
Empagliflozin is a SGLT2 inhibitor that reduces the concentration of blood glucose by inhibiting glucose reabsorption and promoting glucose excretion. Interestingly, empagliflozin also has some additional benefits, including cardiovascular protection, decreasing uric acid levels and improving NAFLD-related liver injury. However, the specific mechanism by which empagliflozin ameliorates NAFLD-related liver injury, especially how empagliflozin regulates hepatic immune inflammatory responses, is still unknown. In this study, male C57BL/6J mice were fed a high-fat diet and injected with streptozotocin to establish an animal model of T2DM with NAFLD. Then, diabetic mice with NAFLD were administered empagliflozin by gavage. We found that empagliflozin ameliorated liver injury and lipid metabolism disorder in T2DM mice with NAFLD. Empagliflozin significantly enhanced autophagy in hepatic macrophages via the AMPK/mTOR signalling pathway. After blocking autophagy and AMPK activity, empagliflozin could not prevent NAFLD-related liver injury. Furthermore, the expression levels of IL-17/IL-23 axis-related molecules were inhibited by empagliflozin through enhancing macrophage autophagy. Inhibition of IL-17/IL-23 axis activity attenuated liver injury in T2DM mice with NAFLD. In summary, these results suggested that empagliflozin could significantly ameliorate NAFLD-related liver injury, through enhancing hepatic macrophage autophagy via the AMPK/mTOR signalling pathway and further inhibiting IL-17/IL-23 axis-mediated inflammatory responses. This study provides a theoretical basis for the rational application of empagliflozin to treat T2DM with NAFLD and improve the quality of life of T2DM patients with NAFLD, which will have social benefits.
Collapse
|
8
|
Lyu M, Shalitana A, Luo J, He H, Sun S, Wang P. Overexpression of the Tuberous sclerosis complex 2 (TSC2) gene inhibits goat myoblasts proliferation and differentiation in understanding the underlying mechanism of muscle development. Gene 2020; 757:144943. [PMID: 32652105 DOI: 10.1016/j.gene.2020.144943] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 06/26/2020] [Accepted: 07/01/2020] [Indexed: 02/06/2023]
Abstract
The growth of animal skeletal muscle is mainly determined by the synthesis processes of total proteins in skeletal muscle cells, which has a significant impact on the postnatal growth of young animals. An increasing number of studies are focusing on the functions of Tuberous sclerosis complex 2 (TSC2) during the process of cell protein synthesis and growth. However, it is still unclear the effect of whether and how TSC2 on goat myoblasts proliferation and differentiation. Here, we found that TSC2 gene has opposite expression patterns in proliferation and differentiation of myoblasts. An expression vector containing goat TSC2 cDNA sequences linked with pcDNA3.1 plasmid was constructed. Myoblasts proliferation activity was significantly inhibited and cell cycle transition slowed down after the transfection of pcDNA3.1-TSC2 plasmid into goat primary myoblasts by EdU staining, CCK-8 and flow cytometry. Mechanically, we further confirmed that the overexpression TSC2 was able to down-regulate the mRNA and protein expression of mechanistic target of rapamycin (mTOR), p70 ribosomal S6 kinase 1 (p70S6K) and some cell cycle related genes. In addition, the expression of myogenic genes and myotube formation were attenuated. Collectively, all our results of the experiment demonstrate that TSC2 could regulate myoblasts cells proliferation and differentiation via the activation of the mTOR/p70S6K signaling pathway.
Collapse
Affiliation(s)
- Ming Lyu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Alai Shalitana
- Department of Xinjiang Institute for Cancer Research, Xinjiang Cancer Hospital of Xinjiang Medical University, Urumqi 830011, China
| | - Jun Luo
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Huanshan He
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Shuang Sun
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Ping Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China.
| |
Collapse
|
9
|
Abstract
Celiac disease (CD) is an enteropathy triggered by the ingestion of gluten proteins in genetically predisposed individuals and characterized by excessive activation of effector immune cells and enhanced production of inflammatory cytokines. However, factors/mechanisms that amplify the ongoing mucosal inflammation in CD are not fully understood. In this study, we assessed whether mammalian target of Rapamycin (mTOR), a pathway that combines intra- and extra-cellular signals and acts as a central regulator for the metabolism, growth, and function of immune and non-immune cells, sustains CD-associated immune response. Our findings indicate that expression of phosphorylated (p)/active form of mTOR is increased in protein lysates of duodenal biopsy samples taken from patients with active CD (ACD) as compared to normal controls. In ACD, activation of mTOR occurs mainly in the epithelial compartment and associates with enhanced expression of p-4EBP, a downstream target of mTOR complex (mTORC)1, while expression of p-Rictor, a component of mTORC2, is not increased. Stimulation of mucosal explants of inactive CD patients with pepsin-trypsin-digested (PT)-gliadin or IFN-γ/IL-21, two cytokines produced in CD by gluten-specific T cells, increases p-4EBP expression. Consistently, blockade of such cytokines in cultures of ACD mucosal explants reduces p-4EBP. Finally, we show that inhibition of mTORC1 with rapamycin in ACD mucosal explants reduces p-4EBP and production of IL-15, a master cytokine produced by epithelial cells in this disorder. Our data suggest that ACD inflammation is marked by activation of mTORC1 in the epithelial compartment.
Collapse
|
10
|
Meena NK, Ralston E, Raben N, Puertollano R. Enzyme Replacement Therapy Can Reverse Pathogenic Cascade in Pompe Disease. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 18:199-214. [PMID: 32671132 PMCID: PMC7334420 DOI: 10.1016/j.omtm.2020.05.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/27/2020] [Indexed: 12/14/2022]
Abstract
Pompe disease, a deficiency of glycogen-degrading lysosomal acid alpha-glucosidase (GAA), is a disabling multisystemic illness that invariably affects skeletal muscle in all patients. The patients still carry a heavy burden of the disease, despite the currently available enzyme replacement therapy. We have previously shown that progressive entrapment of glycogen in the lysosome in muscle sets in motion a whole series of “extra-lysosomal” events including defective autophagy and disruption of a variety of signaling pathways. Here, we report that metabolic abnormalities and energy deficit also contribute to the complexity of the pathogenic cascade. A decrease in the metabolites of the glycolytic pathway and a shift to lipids as the energy source are observed in the diseased muscle. We now demonstrate in a pre-clinical study that a recently developed replacement enzyme (recombinant human GAA; AT-GAA; Amicus Therapeutics) with much improved lysosome-targeting properties reversed or significantly improved all aspects of the disease pathogenesis, an outcome not observed with the current standard of care. The therapy was initiated in GAA-deficient mice with fully developed muscle pathology but without obvious clinical symptoms; this point deserves consideration.
Collapse
Affiliation(s)
- Naresh Kumar Meena
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Evelyn Ralston
- Light Imaging Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD, USA
| | - Nina Raben
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
- Corresponding author Nina Raben, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA.
| | - Rosa Puertollano
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
- Corresponding author Rosa Puertollano, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA.
| |
Collapse
|
11
|
Shi M, Hu Z, Zhang X, You Q, Wang W, Yan R, Zhu Z. AMPK activation suppresses mTOR/S6K1 phosphorylation and induces leucine resistance in rats with sepsis. Cell Biol Int 2020; 44:1133-1141. [PMID: 31943518 DOI: 10.1002/cbin.11310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 01/10/2020] [Indexed: 11/12/2022]
Abstract
Although it has been known that protein synthesis is suppressed in sepsis, which cannot be corrected by leucine supplement (also known as leucine resistance), the molecular signaling mechanism remains unclear. This study aimed to investigate the AMP-activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway in sepsis-induced leucine resistance and its upstream signals, and to seek a way to correct leucine resistance in sepsis. Sepsis was produced by cecal ligation and puncture (CLP) model in rat. Both septic rats and sham operation rat received total parenteral nutrition (TPN) with or without leucine for 24 h, and then protein synthesis and AMPK/mTOR and protein kinase B (PKB) were tested. In vitro C2C12 cells were treated with or without leucine, and we tested the AMPK/mTOR pathway and protein synthesis. We blocked AMPK by compound C and stimulated it by 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) individually. The results showed that AMPK was highly phosphorylated and suppressed mTOR/S6K1 activation in CLP rats. In vitro when AMPK was activated by AICAR, protein synthesis was suppressed and leucine resistance was observed. High phosphorylation of AMPK was accompanied by PKB inactivation in CLP rats. When PKB was blocked, both AMPK activation and leucine resistance were observed. In CLP rats, nutrition support with intensive insulin therapy reversed leucine resistance by activating PKB and suppressing AMPK phosphorylation. These findings suggest that high phosphorylation of AMPK induced by PKB inactivation in sepsis suppresses mTOR, S6K1 phosphorylation, and protein synthesis and leads to leucine resistance. Intensive insulin treatment can reverse leucine resistance by suppressing AMPK activation through activation of PKB.
Collapse
Affiliation(s)
- Mengyao Shi
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| | - Zunqi Hu
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| | - Xin Zhang
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| | - Qing You
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| | - Weimin Wang
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| | - Ronglin Yan
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| | - Zhenxin Zhu
- Gastro-intestine Surgery Department, Shanghai Changzheng Hospital, Second Military Medical University, 415 FengYang Road, Shanghai, 200003, PR China
| |
Collapse
|
12
|
Perspectives of RAS and RHEB GTPase Signaling Pathways in Regenerating Brain Neurons. Int J Mol Sci 2018; 19:ijms19124052. [PMID: 30558189 PMCID: PMC6321366 DOI: 10.3390/ijms19124052] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/05/2018] [Accepted: 12/13/2018] [Indexed: 12/29/2022] Open
Abstract
Cellular activation of RAS GTPases into the GTP-binding “ON” state is a key switch for regulating brain functions. Molecular protein structural elements of rat sarcoma (RAS) and RAS homolog protein enriched in brain (RHEB) GTPases involved in this switch are discussed including their subcellular membrane localization for triggering specific signaling pathways resulting in regulation of synaptic connectivity, axonal growth, differentiation, migration, cytoskeletal dynamics, neural protection, and apoptosis. A beneficial role of neuronal H-RAS activity is suggested from cellular and animal models of neurodegenerative diseases. Recent experiments on optogenetic regulation offer insights into the spatiotemporal aspects controlling RAS/mitogen activated protein kinase (MAPK) or phosphoinositide-3 kinase (PI3K) pathways. As optogenetic manipulation of cellular signaling in deep brain regions critically requires penetration of light through large distances of absorbing tissue, we discuss magnetic guidance of re-growing axons as a complementary approach. In Parkinson’s disease, dopaminergic neuronal cell bodies degenerate in the substantia nigra. Current human trials of stem cell-derived dopaminergic neurons must take into account the inability of neuronal axons navigating over a large distance from the grafted site into striatal target regions. Grafting dopaminergic precursor neurons directly into the degenerating substantia nigra is discussed as a novel concept aiming to guide axonal growth by activating GTPase signaling through protein-functionalized intracellular magnetic nanoparticles responding to external magnets.
Collapse
|
13
|
Yoshida S, Pacitto R, Inoki K, Swanson J. Macropinocytosis, mTORC1 and cellular growth control. Cell Mol Life Sci 2018; 75:1227-1239. [PMID: 29119228 PMCID: PMC5843684 DOI: 10.1007/s00018-017-2710-y] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/31/2017] [Accepted: 11/03/2017] [Indexed: 12/15/2022]
Abstract
The growth and proliferation of metazoan cells are driven by cellular nutrient status and by extracellular growth factors. Growth factor receptors on cell surfaces initiate biochemical signals that increase anabolic metabolism and macropinocytosis, an actin-dependent endocytic process in which relatively large volumes of extracellular solutes and nutrients are internalized and delivered efficiently into lysosomes. Macropinocytosis is prominent in many kinds of cancer cells, and supports the growth of cells transformed by oncogenic K-Ras. Growth factor receptor signaling and the overall metabolic status of the cell are coordinated in the cytoplasm by the mechanistic target-of-rapamycin complex-1 (mTORC1), which positively regulates protein synthesis and negatively regulates molecular salvage pathways such as autophagy. mTORC1 is activated by two distinct Ras-related small GTPases, Rag and Rheb, which associate with lysosomal membranes inside the cell. Rag recruits mTORC1 to the lysosomal surface where Rheb directly binds to and activates mTORC1. Rag is activated by both lysosomal luminal and cytosolic amino acids; Rheb activation requires phosphoinositide 3-kinase, Akt, and the tuberous sclerosis complex-1/2. Signals for activation of Rag and Rheb converge at the lysosomal membrane, and several lines of evidence support the idea that growth factor-dependent endocytosis facilitates amino acid transfer into the lysosome leading to the activation of Rag. This review summarizes evidence that growth factor-stimulated macropinocytosis is essential for amino acid-dependent activation of mTORC1, and that increased solute accumulation by macropinocytosis in transformed cells supports unchecked cell growth.
Collapse
Affiliation(s)
- Sei Yoshida
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109-5620, USA
| | - Regina Pacitto
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109-5620, USA
| | - Ken Inoki
- Department of Integrative and Molecular Physiology and Internal Medicine, Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Joel Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109-5620, USA.
| |
Collapse
|
14
|
Potheraveedu VN, Schöpel M, Stoll R, Heumann R. Rheb in neuronal degeneration, regeneration, and connectivity. Biol Chem 2017; 398:589-606. [PMID: 28212107 DOI: 10.1515/hsz-2016-0312] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 02/02/2017] [Indexed: 01/31/2023]
Abstract
The small GTPase Rheb was originally detected as an immediate early response protein whose expression was induced by NMDA-dependent synaptic activity in the brain. Rheb's activity is highly regulated by its GTPase activating protein (GAP), the tuberous sclerosis complex protein, which stimulates the conversion from the active, GTP-loaded into the inactive, GDP-loaded conformation. Rheb has been established as an evolutionarily conserved molecular switch protein regulating cellular growth, cell volume, cell cycle, autophagy, and amino acid uptake. The subcellular localization of Rheb and its interacting proteins critically regulate its activity and function. In stem cells, constitutive activation of Rheb enhances differentiation at the expense of self-renewal partially explaining the adverse effects of deregulated Rheb in the mammalian brain. In the context of various cellular stress conditions such as oxidative stress, ER-stress, death factor signaling, and cellular aging, Rheb activation surprisingly enhances rather than prevents cellular degeneration. This review addresses cell type- and cell state-specific function(s) of Rheb and mainly focuses on neurons and their surrounding glial cells. Mechanisms will be discussed in the context of therapy that interferes with Rheb's activity using the antibiotic rapamycin or low molecular weight compounds.
Collapse
Affiliation(s)
- Veena Nambiar Potheraveedu
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
| | - Miriam Schöpel
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Rolf Heumann
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
| |
Collapse
|
15
|
Nagai K, Tominaga T, Ueda S, Shibata E, Tamaki M, Matsuura M, Kishi S, Murakami T, Moriya T, Abe H, Doi T. Mesangial Cell Mammalian Target of Rapamycin Complex 1 Activation Results in Mesangial Expansion. J Am Soc Nephrol 2017; 28:2879-2885. [PMID: 28701517 DOI: 10.1681/asn.2016111196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 06/02/2017] [Indexed: 02/05/2023] Open
Abstract
Human glomerular diseases can be caused by several different diseases, many of which include mesangial expansion and/or proliferation followed by glomerulosclerosis. However, molecular mechanisms underlying the pathologic mesangial changes remain poorly understood. Here, we investigated the role of the mammalian target of rapamycin complex 1 (mTORC1)-S6 kinase pathway in mesangial expansion and/or proliferation by ablating an upstream negative regulator, tuberous sclerosis complex 1 (TSC1), using tamoxifen-induced Foxd1-Cre mice [Foxd1ER(+) TSC1 mice]. Foxd1ER(+) TSC1 mice showed mesangial expansion with increased production of collagen IV, collagen I, and α-smooth muscle actin in glomeruli, but did not exhibit significant mesangial proliferation or albuminuria. Furthermore, rapamycin treatment of Foxd1ER(+) TSC1 mice suppressed mesangial expansion. Among biopsy specimens from patients with glomerular diseases, analysis of phosphorylated ribosomal protein S6 revealed mesangial cell mTORC1 activation in IgA nephropathy and in lupus mesangial proliferative nephritis but not in the early phase of diabetic nephropathy. In summary, mesangial cell mTORC1 activation can cause mesangial expansion and has clinical relevance for human glomerular diseases. This report also confirms that the tamoxifen-induced mesangium-specific Cre-loxP system is useful for studies designed to clarify the role of the mesangium in glomerular diseases in adults.
Collapse
Affiliation(s)
- Kojiro Nagai
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Tatsuya Tominaga
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Sayo Ueda
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Eriko Shibata
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Masanori Tamaki
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Motokazu Matsuura
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Seiji Kishi
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Taichi Murakami
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Tatsumi Moriya
- Health Care Center, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Hideharu Abe
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Toshio Doi
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| |
Collapse
|
16
|
Mo H, He J, Yuan Z, Mo L, Wu Z, Lin X, Liu B, Guan J. WT1 is involved in the Akt-JNK pathway dependent autophagy through directly regulating Gas1 expression in human osteosarcoma cells. Biochem Biophys Res Commun 2016; 478:74-80. [PMID: 27453337 DOI: 10.1016/j.bbrc.2016.07.090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 07/20/2016] [Indexed: 11/28/2022]
Abstract
Macroautophagy (herein termed autophagy) works as a protective mechanism in tumorigenesis and development under metabolic stress condition. Multitudes of genes have been found involved in this process during past decades. In the present study, we report that Wilm's tumor suppressor1 (WT1) is involved in autophagy in osteosarcoma (OS) cells. WT1, a transcription factor with multitude of target genes, expresses in a majority of cancer types. Though wide-ranging effect of WT1 is now well documented, the function of WT1 in tumors remains poorly defined. In this chapter, it is found that high expression of WT1 positively correlates with active autophagy in human osteosarcoma cells. And further study on cell signaling pathway illustrates that Akt/JNK pathway acts as a positive regulator of autophagy induced by WT1. Here, we present evidence that WT1 modulates Akt/JNK signaling pathway mediated autophagy by controlling the expression of growth arrest-specific 1 (Gas1). We show that WT1 is required for Gas1 transcription in osteosarcoma cells. And Gas1 is upregulated followed WT1 overexpression in a time-dependent manner. Loss of Gas1 results in a reduction of WT1-induced autophagy.
Collapse
Affiliation(s)
- Hao Mo
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Juliang He
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Zhenchao Yuan
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Ligen Mo
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Zhenjie Wu
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Xiang Lin
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Bin Liu
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China
| | - Jian Guan
- Department of Bone and Soft Tissue Neurosurgery, Affiliated Tumor Hospital of Guangxi Medical University, People's Republic of China.
| |
Collapse
|
17
|
Hao F, Itoh T, Morita E, Shirahama-Noda K, Yoshimori T, Noda T. The PtdIns3-phosphatase MTMR3 interacts with mTORC1 and suppresses its activity. FEBS Lett 2015; 590:161-73. [PMID: 26787466 PMCID: PMC5064752 DOI: 10.1002/1873-3468.12048] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 12/11/2015] [Accepted: 12/13/2015] [Indexed: 12/12/2022]
Abstract
Macroautophagy is a major intracellular degradation system. We previously reported that overexpression of phosphatase-deficient MTMR3, a member of the myotubularin phosphatidylinositol (PI) 3-phosphatase family, leads to induction of autophagy. In this study, we found that MTMR3 interacted with mTORC1, an evolutionarily conserved serine/threonine kinase complex, which regulates cell growth and autophagy in response to environmental stimuli. Furthermore, overexpression of MTMR3 inhibited mTORC1 activity. The N-terminal half of MTMR3, including the PH-G and phosphatase domains, was necessary and sufficient for these effects. Phosphatase-deficient MTMR3 provided more robust suppression of mTORC1 activity than wild-type MTMR3. Furthermore, phosphatase-deficient full length MTMR3 and the phosphatase domain alone were localized to the Golgi. These results suggest a new regulatory mechanism of mTORC1 in association with PI3P.
Collapse
Affiliation(s)
- Feike Hao
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Japan.,Department of Genetics, Graduate School of Medicine, Osaka University, Japan
| | - Takashi Itoh
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Japan
| | - Eiji Morita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Japan
| | - Kanae Shirahama-Noda
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Japan
| | - Tamotsu Yoshimori
- Department of Genetics, Graduate School of Medicine, Osaka University, Japan.,Graduate School of Frontier Biosciences, Osaka University, Japan
| | - Takeshi Noda
- Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University, Japan.,Graduate School of Frontier Biosciences, Osaka University, Japan
| |
Collapse
|
18
|
Abstract
Lysosomes are acidic compartments filled with more than 60 different types of hydrolases. They mediate the degradation of extracellular particles from endocytosis and of intracellular components from autophagy. The digested products are transported out of the lysosome via specific catabolite exporters or via vesicular membrane trafficking. Lysosomes also contain more than 50 membrane proteins and are equipped with the machinery to sense nutrient availability, which determines the distribution, number, size, and activity of lysosomes to control the specificity of cargo flux and timing (the initiation and termination) of degradation. Defects in degradation, export, or trafficking result in lysosomal dysfunction and lysosomal storage diseases (LSDs). Lysosomal channels and transporters mediate ion flux across perimeter membranes to regulate lysosomal ion homeostasis, membrane potential, catabolite export, membrane trafficking, and nutrient sensing. Dysregulation of lysosomal channels underlies the pathogenesis of many LSDs and possibly that of metabolic and common neurodegenerative diseases.
Collapse
Affiliation(s)
- Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109;
| | | |
Collapse
|
19
|
Zhang L, Liu L, He Z, Li G, Liu J, Song Z, Jin H, Rudolph KL, Yang H, Mao Y, Zhang L, Zhang H, Xiao Z, Ju Z. Inhibition of wild-type p53-induced phosphatase 1 promotes liver regeneration in mice by direct activation of mammalian target of rapamycin. Hepatology 2015; 61:2030-41. [PMID: 25704606 DOI: 10.1002/hep.27755] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 02/14/2015] [Indexed: 12/21/2022]
Abstract
UNLABELLED The liver possesses extraordinary regenerative capacity in response to injury. However, liver regeneration (LR) is often impaired in disease conditions. Wild-type p53-induced phosphatase 1 (Wip1) is known as a tumor promoter and enhances cell proliferation, mainly by deactivating antioncogenes. However, in this work, we identified an unexpected role of Wip1 in LR. In contrast to its known role in promoting cell proliferation in extrahepatic tissue, we found that Wip1 suppressed hepatocyte proliferation after partial hepatectomy (PHx). Deletion of Wip1 increased the rate of LR after PHx. Enhanced LR in Wip1-deficient mice was a result of the activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) pathway. Furthermore, we showed that Wip1 physically interacted with and dephosphorylated mTOR. Interestingly, inhibition of Wip1 also activated the p53 pathway during LR. Disruption of the p53 pathway further enhanced LR in Wip1-deficient mice. Therefore, inhibition of Wip1 has a dual role in LR, i.e., promoting hepatocyte proliferation through activation of the mTORC1 pathway, meanwhile suppressing LR through activation of the p53 pathway. However, the proregenerative role of mTORC1 overwhelms the antiproliferative role of p53. Furthermore, CCT007093, a Wip1 inhibitor, enhanced LR and increased the survival rate of mice after major hepatectomy. CONCLUSION mTOR is a new direct target of Wip1. Wip1 inhibition can activate the mTORC1 pathway and enhance hepatocyte proliferation after hepatectomy. These findings have clinical applications in cases where LR is critical, including acute liver failure, cirrhosis, or small-for-size liver transplantations.
Collapse
Affiliation(s)
- Lingling Zhang
- Institute of Aging Research, Leibniz Link Partner Group on Stem Cell Aging, School of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Leiming Liu
- Sir Runrun Shaw Hospital, Medical School, Zhejiang University, Hangzhou, China
| | - Zhiyong He
- The Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming, China
| | - Guangbing Li
- Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Junping Liu
- Institute of Aging Research, Leibniz Link Partner Group on Stem Cell Aging, School of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Zhangfa Song
- Sir Runrun Shaw Hospital, Medical School, Zhejiang University, Hangzhou, China
| | - Hongchuan Jin
- Sir Runrun Shaw Hospital, Medical School, Zhejiang University, Hangzhou, China
| | | | - Huayu Yang
- Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Yilei Mao
- Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Lianfeng Zhang
- Institute of Laboratory Animal Sciences, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Hongbing Zhang
- Institute of Basic Medical Sciences and School of Basic Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Zhicheng Xiao
- The Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming, China
| | - Zhenyu Ju
- Institute of Aging Research, Leibniz Link Partner Group on Stem Cell Aging, School of Medicine, Hangzhou Normal University, Hangzhou, China
| |
Collapse
|
20
|
Huang K, Fingar DC. Growing knowledge of the mTOR signaling network. Semin Cell Dev Biol 2014; 36:79-90. [PMID: 25242279 DOI: 10.1016/j.semcdb.2014.09.011] [Citation(s) in RCA: 225] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/05/2014] [Accepted: 09/10/2014] [Indexed: 12/14/2022]
Abstract
The kinase mTOR (mechanistic target of rapamycin) integrates diverse environmental signals and translates these cues into appropriate cellular responses. mTOR forms the catalytic core of at least two functionally distinct signaling complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). mTORC1 promotes anabolic cellular metabolism in response to growth factors, nutrients, and energy and functions as a master controller of cell growth. While significantly less well understood than mTORC1, mTORC2 responds to growth factors and controls cell metabolism, cell survival, and the organization of the actin cytoskeleton. mTOR plays critical roles in cellular processes related to tumorigenesis, metabolism, immune function, and aging. Consequently, aberrant mTOR signaling contributes to myriad disease states, and physicians employ mTORC1 inhibitors (rapamycin and analogs) for several pathological conditions. The clinical utility of mTOR inhibition underscores the important role of mTOR in organismal physiology. Here we review our growing knowledge of cellular mTOR regulation by diverse upstream signals (e.g. growth factors; amino acids; energy) and how mTORC1 integrates these signals to effect appropriate downstream signaling, with a greater emphasis on mTORC1 over mTORC2. We highlight dynamic subcellular localization of mTORC1 and associated factors as an important mechanism for control of mTORC1 activity and function. We will cover major cellular functions controlled by mTORC1 broadly. While significant advances have been made in the last decade regarding the regulation and function of mTOR within complex cell signaling networks, many important findings remain to be discovered.
Collapse
Affiliation(s)
- Kezhen Huang
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, United States
| | - Diane C Fingar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, United States; Division of Metabolism, Endocrinology, and Diabetes (MEND), Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-2200, United States.
| |
Collapse
|