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Wang L, Xie Z, Wu M, Chen Y, Wang X, Li X, Liu F. The role of taurine through endoplasmic reticulum in physiology and pathology. Biochem Pharmacol 2024; 226:116386. [PMID: 38909788 DOI: 10.1016/j.bcp.2024.116386] [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: 03/09/2024] [Revised: 06/17/2024] [Accepted: 06/20/2024] [Indexed: 06/25/2024]
Abstract
Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.
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Affiliation(s)
- Linfeng Wang
- Institute of Microbial Engineering, School of Life Sciences, Henan University, Kaifeng 475004, China; Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Zhenxing Xie
- School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Mengxian Wu
- Institute of Microbial Engineering, School of Life Sciences, Henan University, Kaifeng 475004, China; Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Yunayuan Chen
- Institute of Microbial Engineering, School of Life Sciences, Henan University, Kaifeng 475004, China; Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Xin Wang
- Institute of Microbial Engineering, School of Life Sciences, Henan University, Kaifeng 475004, China; Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Xingke Li
- Institute of Microbial Engineering, School of Life Sciences, Henan University, Kaifeng 475004, China; Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China.
| | - Fangli Liu
- College of Nursing and Health, Henan University, Kaifeng 475004, China.
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Lin Q, Tu X, Li X, Gou F, Ding L, Lu Z, Feng J, Ying Y, Hu C. Effects of electrolyte balance on intestinal barrier, amino acid metabolism, and mTORC1 signaling pathway in piglets fed low-protein diets. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2024; 17:408-417. [PMID: 38812495 PMCID: PMC11134538 DOI: 10.1016/j.aninu.2024.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/28/2024] [Accepted: 03/28/2024] [Indexed: 05/31/2024]
Abstract
A proper dietary electrolyte balance (dEB) is essential to ensure optimal growth performance of piglets. In the low-protein diet, this balance may be affected by the reduction of soybean meal and the inclusion of high levels of synthetic amino acids. The objective of this experiment was to evaluate the optimal dEB of low-protein diets and its impact on the growth performance of piglets. A total of 108 piglets (initial age of 35 d) were randomly divided into 3 groups with 6 replicates of 6 pigs each as follows: low electrolyte diet (LE group; dEB = 150 milliequivalents [mEq]/kg); medium electrolyte diet (ME group; dEB = 250 mEq/kg); high electrolyte diet (HE group; dEB = 350 mEq/kg). Results indicated that the LE and HE diet significantly decreased the average daily gain, average daily feed intake, and crude protein digestibility (P < 0.05) in piglets. Meanwhile, LE diets disrupted the structural integrity of the piglets' intestines and decreased jejunal tight junction protein (occludin and claudin-1) expression (P < 0.05). Additionally, the pH and HCO3- in the arterial blood of piglets in the LE group were lower than those in the ME and HE groups (P < 0.05). Interestingly, the LE diet significantly increased lysine content in piglet serum (P < 0.05), decreased the levels of arginine, leucine, glutamic acid, and alanine (P < 0.05), and inhibited the mammalian target of rapamycin complex 1 (mTORC1) pathway by decreasing the phosphorylation abundance of key proteins. In summary, the dietary electrolyte imbalance could inhibit the activation of the mTORC1 signaling pathway, which might be a key factor in the influence of the dEB on piglet growth performance and intestinal health. Moreover, second-order polynomial (quadratic) regression analysis showed that the optimal dEB of piglets in the low-protein diet was 250 to 265 mEq/kg.
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Affiliation(s)
- Qian Lin
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
| | - Xiaodian Tu
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
| | - Xin Li
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
| | - Feiyang Gou
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
| | - Lin Ding
- Animal Husbandry Technology Promotion and Breeding Livestock and Poultry Monitoring Station of Zhejiang Province, Hangzhou 310000, China
| | - Zeqing Lu
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
| | - Jie Feng
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
| | - Yongfei Ying
- Animal Husbandry Technology Promotion and Breeding Livestock and Poultry Monitoring Station of Zhejiang Province, Hangzhou 310000, China
| | - Caihong Hu
- College of Animal Sciences, Zhejiang University, Key Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou 310058, China
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Lv S, Zhang Z, Li Z, Ke Q, Ma X, Li N, Zhao X, Zou Q, Sun L, Song T. TFE3-SLC36A1 axis promotes resistance to glucose starvation in kidney cancer cells. J Biol Chem 2024; 300:107270. [PMID: 38599381 PMCID: PMC11098960 DOI: 10.1016/j.jbc.2024.107270] [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: 12/19/2023] [Revised: 03/14/2024] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
Higher demand for nutrients including glucose is characteristic of cancer. "Starving cancer" has been pursued to curb tumor progression. An intriguing regime is to inhibit glucose transporter GLUT1 in cancer cells. In addition, during cancer progression, cancer cells may suffer from insufficient glucose supply. Yet, cancer cells can somehow tolerate glucose starvation. Uncovering the underlying mechanisms shall shed insight into cancer progression and benefit cancer therapy. TFE3 is a transcription factor known to activate autophagic genes. Physiological TFE3 activity is regulated by phosphorylation-triggered translocation responsive to nutrient status. We recently reported TFE3 constitutively localizes to the cell nucleus and promotes cell proliferation in kidney cancer even under nutrient replete condition. It remains unclear whether and how TFE3 responds to glucose starvation. In this study, we show TFE3 promotes kidney cancer cell resistance to glucose starvation by exposing cells to physiologically relevant glucose concentration. We find glucose starvation triggers TFE3 protein stabilization through increasing its O-GlcNAcylation. Furthermore, through an unbiased functional genomic study, we identify SLC36A1, a lysosomal amino acid transporter, as a TFE3 target gene sensitive to TFE3 protein level. We find SLC36A1 is overexpressed in kidney cancer, which promotes mTOR activity and kidney cancer cell proliferation. Importantly, SLC36A1 level is induced by glucose starvation through TFE3, which enhances cellular resistance to glucose starvation. Suppressing TFE3 or SLC36A1 significantly increases cellular sensitivity to GLUT1 inhibitor in kidney cancer cells. Collectively, we uncover a functional TFE3-SLC36A1 axis that responds to glucose starvation and enhances starvation tolerance in kidney cancer.
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Affiliation(s)
- Suli Lv
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zongbiao Zhang
- Department and Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhenyong Li
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qian Ke
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xianyun Ma
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Neng Li
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuefeng Zhao
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qingli Zou
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lidong Sun
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Cell Architecture Research Institute, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Tanjing Song
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Cell Architecture Research Institute, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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Barone S, Zahedi K, Brooks M, Soleimani M. Carbonic Anhydrase 2 Deletion Delays the Growth of Kidney Cysts Whereas Foxi1 Deletion Completely Abrogates Cystogenesis in TSC. Int J Mol Sci 2024; 25:4772. [PMID: 38731991 PMCID: PMC11084925 DOI: 10.3390/ijms25094772] [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: 03/15/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
Tuberous sclerosis complex (TSC) presents with renal cysts and benign tumors, which eventually lead to kidney failure. The factors promoting kidney cyst formation in TSC are poorly understood. Inactivation of carbonic anhydrase 2 (Car2) significantly reduced, whereas, deletion of Foxi1 completely abrogated the cyst burden in Tsc1 KO mice. In these studies, we contrasted the ontogeny of cyst burden in Tsc1/Car2 dKO mice vs. Tsc1/Foxi1 dKO mice. Compared to Tsc1 KO, the Tsc1/Car2 dKO mice showed few small cysts at 47 days of age. However, by 110 days, the kidneys showed frequent and large cysts with overwhelming numbers of A-intercalated cells in their linings. The magnitude of cyst burden in Tsc1/Car2 dKO mice correlated with the expression levels of Foxi1 and was proportional to mTORC1 activation. This is in stark contrast to Tsc1/Foxi1 dKO mice, which showed a remarkable absence of kidney cysts at both 47 and 110 days of age. RNA-seq data pointed to profound upregulation of Foxi1 and kidney-collecting duct-specific H+-ATPase subunits in 110-day-old Tsc1/Car2 dKO mice. We conclude that Car2 inactivation temporarily decreases the kidney cyst burden in Tsc1 KO mice but the cysts increase with advancing age, along with enhanced Foxi1 expression.
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Affiliation(s)
- Sharon Barone
- Research Services, New Mexico Veterans Health Care System, Albuquerque, NM 87108, USA; (S.B.); (K.Z.); (M.B.)
- Department of Medicine, Division of Nephrology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Kamyar Zahedi
- Research Services, New Mexico Veterans Health Care System, Albuquerque, NM 87108, USA; (S.B.); (K.Z.); (M.B.)
- Department of Medicine, Division of Nephrology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Marybeth Brooks
- Research Services, New Mexico Veterans Health Care System, Albuquerque, NM 87108, USA; (S.B.); (K.Z.); (M.B.)
- Department of Medicine, Division of Nephrology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Manoocher Soleimani
- Research Services, New Mexico Veterans Health Care System, Albuquerque, NM 87108, USA; (S.B.); (K.Z.); (M.B.)
- Department of Medicine, Division of Nephrology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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Settembre C, Perera RM. Lysosomes as coordinators of cellular catabolism, metabolic signalling and organ physiology. Nat Rev Mol Cell Biol 2024; 25:223-245. [PMID: 38001393 DOI: 10.1038/s41580-023-00676-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2023] [Indexed: 11/26/2023]
Abstract
Every cell must satisfy basic requirements for nutrient sensing, utilization and recycling through macromolecular breakdown to coordinate programmes for growth, repair and stress adaptation. The lysosome orchestrates these key functions through the synchronised interplay between hydrolytic enzymes, nutrient transporters and signalling factors, which together enable metabolic coordination with other organelles and regulation of specific gene expression programmes. In this Review, we discuss recent findings on lysosome-dependent signalling pathways, focusing on how the lysosome senses nutrient availability through its physical and functional association with mechanistic target of rapamycin complex 1 (mTORC1) and how, in response, the microphthalmia/transcription factor E (MiT/TFE) transcription factors exert feedback regulation on lysosome biogenesis. We also highlight the emerging interactions of lysosomes with other organelles, which contribute to cellular homeostasis. Lastly, we discuss how lysosome dysfunction contributes to diverse disease pathologies and how inherited mutations that compromise lysosomal hydrolysis, transport or signalling components lead to multi-organ disorders with severe metabolic and neurological impact. A deeper comprehension of lysosomal composition and function, at both the cellular and organismal level, may uncover fundamental insights into human physiology and disease.
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Affiliation(s)
- Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy.
- Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy.
| | - Rushika M Perera
- Department of Anatomy, University of California at San Francisco, San Francisco, CA, USA.
- Department of Pathology, University of California at San Francisco, San Francisco, CA, USA.
- Helen Diller Family Comprehensive Cancer Center, University of California at San Francisco, San Francisco, CA, USA.
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Jakobsen S, Nielsen CU. Exploring Amino Acid Transporters as Therapeutic Targets for Cancer: An Examination of Inhibitor Structures, Selectivity Issues, and Discovery Approaches. Pharmaceutics 2024; 16:197. [PMID: 38399253 PMCID: PMC10893028 DOI: 10.3390/pharmaceutics16020197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/18/2024] [Accepted: 01/28/2024] [Indexed: 02/25/2024] Open
Abstract
Amino acid transporters are abundant amongst the solute carrier family and have an important role in facilitating the transfer of amino acids across cell membranes. Because of their impact on cell nutrient distribution, they also appear to have an important role in the growth and development of cancer. Naturally, this has made amino acid transporters a novel target of interest for the development of new anticancer drugs. Many attempts have been made to develop inhibitors of amino acid transporters to slow down cancer cell growth, and some have even reached clinical trials. The purpose of this review is to help organize the available information on the efforts to discover amino acid transporter inhibitors by focusing on the amino acid transporters ASCT2 (SLC1A5), LAT1 (SLC7A5), xCT (SLC7A11), SNAT1 (SLC38A1), SNAT2 (SLC38A2), and PAT1 (SLC36A1). We discuss the function of the transporters, their implication in cancer, their known inhibitors, issues regarding selective inhibitors, and the efforts and strategies of discovering inhibitors. The goal is to encourage researchers to continue the search and development within the field of cancer treatment research targeting amino acid transporters.
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Affiliation(s)
- Sebastian Jakobsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark
| | - Carsten Uhd Nielsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark
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Soleimani M. Not all kidney cysts are created equal: a distinct renal cystogenic mechanism in tuberous sclerosis complex (TSC). Front Physiol 2023; 14:1289388. [PMID: 38028758 PMCID: PMC10663234 DOI: 10.3389/fphys.2023.1289388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/18/2023] [Indexed: 12/01/2023] Open
Abstract
Tuberous Sclerosis Complex (TSC) is an autosomal dominant genetic disease caused by mutations in either TSC1 or TSC2 genes. Approximately, two million individuals suffer from this disorder worldwide. TSC1 and TSC2 code for the proteins harmartin and tuberin, respectively, which form a complex that regulates the mechanistic target of rapamycin complex 1 (mTORC1) and prevents uncontrollable cell growth. In the kidney, TSC presents with the enlargement of benign tumors (angiomyolipomas) and cysts whose presence eventually causes kidney failure. The factors promoting cyst formation and tumor growth in TSC are poorly understood. Recent studies on kidney cysts in various mouse models of TSC, including mice with principal cell- or pericyte-specific inactivation of TSC1 or TSC2, have identified a unique cystogenic mechanism. These studies demonstrate the development of numerous cortical cysts that are predominantly comprised of hyperproliferating A-intercalated (A-IC) cells that express both TSC1 and TSC2. An analogous cellular phenotype in cystic epithelium is observed in both humans with TSC and in TSC2+/- mice, confirming a similar kidney cystogenesis mechanism in TSC. This cellular phenotype profoundly contrasts with kidney cysts found in Autosomal Dominant Polycystic Kidney Disease (ADPKD), which do not show any notable evidence of A-IC cells participating in the cyst lining or expansion. RNA sequencing (RNA-Seq) and confirmatory expression studies demonstrate robust expression of Forkhead Box I1 (FOXI1) transcription factor and its downstream targets, including apical H+-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in the cyst epithelia of Tsc1 (or Tsc2) knockout (KO) mice, but not in Polycystic Kidney Disease (Pkd1) mutant mice. Deletion of FOXI1, which is vital to H+-ATPase expression and intercalated (IC) cell viability, completely inhibited mTORC1 activation and abrogated the cyst burden in the kidneys of Tsc1 KO mice. These results unequivocally demonstrate the critical role that FOXI1 and A-IC cells, along with H+-ATPase, play in TSC kidney cystogenesis. This review article will discuss the latest research into the causes of kidney cystogenesis in TSC with a focus on possible therapeutic options for this devastating disease.
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Affiliation(s)
- Manoocher Soleimani
- Department of Medicine, New Mexico Veterans Health Care Center, Albuquerque, NM, United States
- Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
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Socha C, Pais IS, Lee KZ, Liu J, Liégeois S, Lestradet M, Ferrandon D. Fast drosophila enterocyte regrowth after infection involves a reverse metabolic flux driven by an amino acid transporter. iScience 2023; 26:107490. [PMID: 37636057 PMCID: PMC10448536 DOI: 10.1016/j.isci.2023.107490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/30/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
Upon exposure to a bacterial pore-forming toxin, enterocytes rapidly purge their apical cytoplasm into the gut lumen, resulting in a thin intestinal epithelium. The enterocytes regain their original shape and thickness within 16 h after the ingestion of the bacteria. Here, we show that the regrowth of Drosophila enterocytes entails an inversion of metabolic fluxes from the organism back toward the intestine. We identify a proton-assisted transporter, Arcus, that is required for the reverse absorption of amino acids and the timely recovery of the intestinal epithelium. Arcus is required for a peak of amino acids appearing in the hemolymph shortly after infection. The regrowth of enterocytes involves the insulin signaling pathway and Myc. The purge decreases Myc mRNA levels, which subsequently remain at low levels in the arcus mutant. Interestingly, the action of arcus and Myc in the intestinal epithelium is not cell-autonomous, suggesting amino acid fluxes within the intestinal epithelium.
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Affiliation(s)
- Catherine Socha
- Université de Strasbourg, CNRS, RIDI UPR 9022, F67084 Strasbourg, France
| | - Inês S. Pais
- Université de Strasbourg, CNRS, RIDI UPR 9022, F67084 Strasbourg, France
| | - Kwang-Zin Lee
- Université de Strasbourg, CNRS, RIDI UPR 9022, F67084 Strasbourg, France
| | - Jiyong Liu
- Sino-French Hoffmann Institute, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou 511436, Guangdong Province, China
| | - Samuel Liégeois
- Université de Strasbourg, CNRS, RIDI UPR 9022, F67084 Strasbourg, France
- Sino-French Hoffmann Institute, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou 511436, Guangdong Province, China
| | - Matthieu Lestradet
- Université de Strasbourg, CNRS, RIDI UPR 9022, F67084 Strasbourg, France
| | - Dominique Ferrandon
- Université de Strasbourg, CNRS, RIDI UPR 9022, F67084 Strasbourg, France
- Sino-French Hoffmann Institute, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou 511436, Guangdong Province, China
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Kobayashi T, Toyama-Sorimachi N. Metabolic control from the endolysosome: lysosome-resident amino acid transporters open novel therapeutic possibilities. Front Immunol 2023; 14:1243104. [PMID: 37781390 PMCID: PMC10540624 DOI: 10.3389/fimmu.2023.1243104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/23/2023] [Indexed: 10/03/2023] Open
Abstract
Amino acid transporters are generally recognized as machinery that transport amino acids from the extracellular environment into the cytoplasm. Although their primary function is the uptake of amino acids to supply the cell with nutrients and energy, endolysosome-resident amino acid (EL-aa) transporters possess several unique functions in accordance with their localization in intracellular vesicular membranes. They play pivotal roles in the maintenance of metabolic homeostasis via direct involvement in the amino acid sensing pathway, which regulates the activity of mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of cellular metabolism. Additionally, some EL-aa transporters contribute to the maintenance of dynamic homeostasis of endolysosomes, including the regulation of endolysosomal acidity, by carrying amino acids out of endolysosomes. In addition, EL-aa transporters act as a scaffold to gather signaling molecules and multiple enzymes to control cellular metabolism on the endolysosomal membrane. Among EL-aa transporters, solute carrier family 15 member 4 (SLC15A4) is preferentially expressed in immune cells, including macrophages, dendritic cells, and B cells, and plays a key role in the integration of metabolic and inflammatory signals. In this review, we summarize our recent findings on EL-aa transporter contributions to inflammatory and metabolic signaling in the endolysosomes of immune cells by focusing on the SLC15 family, including SLC15A4 and SLC15A3, and discuss their uniqueness and universality. We also discuss the potential of targeting these EL-aa transporters in immune cells for the development of novel therapeutic strategies for inflammatory diseases. Because these transporters are highly expressed in immune cells and significantly alter the functions of immune cells, targeting them would provide a great advantage in ensuring a wide safety margin.
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Affiliation(s)
| | - Noriko Toyama-Sorimachi
- Division of Human Immunology, International Research and Development Center for Vaccines, The Institute of Medical Science, The University of Tokyo (IMSUT), Tokyo, Japan
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Piro F, Masci S, Kannan G, Focaia R, Schultz TL, Carruthers VB, Di Cristina M. A Toxoplasma gondii putative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555807. [PMID: 37693549 PMCID: PMC10491228 DOI: 10.1101/2023.08.31.555807] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Toxoplasma gondii is a protozoan parasite that infects a broad spectrum of hosts and can colonize many organs and cell types. The ability to reside within a wide range of different niches requires substantial adaptability to diverse microenvironments. Very little is known about how this parasite senses various milieus and adapts its metabolism to survive, replicate during the acute stage, and then differentiate to the chronic stage. Most eukaryotes, from yeast to mammals, rely on a nutrient sensing machinery involving the TORC complex as master regulator of cell growth and cell cycle progression. The lysosome functions as a signaling hub where TORC complex assembles and is activated by transceptors, which both sense and transport amino acids, including the arginine transceptor SLC38A9. While most of the TORC components are lost in T. gondii , indicating the evolution of a distinct nutrient sensing mechanism, the parasite's lysosomal plant-like vacuolar compartment (PLVAC) may still serve as a sensory platform for controlling parasite growth and differentiation. Using SLC38A9 to query the T. gondii proteome, we identified four putative amino acid transporters, termed TgAAT1-4, that structurally resemble the SLC38A9 arginine transceptor. Assessing their expression and sub-cellular localization, we found that one of them, TgAAT1, localized to the PLVAC and is necessary for normal parasite extracellular survival and bradyzoite differentiation. Moreover, we show that TgAAT1 is involved in the PLVAC efflux of arginine, an amino acid playing a key role in T. gondii differentiation, further supporting the hypothesis that TgAAT1 might play a role in nutrient sensing. IMPORTANCE T. gondii is a highly successful parasite infecting a broad range of warm-blood organisms including about one third of all humans. Although Toxoplasma infections rarely result in symptomatic disease in individuals with a healthy immune system, the incredibly high number of persons infected along with the risk of severe infection in immunocompromised patients and the potential link of chronic infection to mental disorders make this infection a significant public health concern. As a result, there is a pressing need for new treatment approaches that are both effective and well-tolerated. The limitations in understanding how Toxoplasma gondii manages its metabolism to adapt to changing environments and triggers its transformation into bradyzoites have hindered the discovery of vulnerabilities in its metabolic pathways or nutrient acquisition mechanisms to identify new therapeutic targets. In this work, we have shown that the lysosome-like organelle PLVAC, acting through the putative arginine transporter TgAAT1, plays a pivotal role in regulating the parasite's extracellular survival and differentiation into bradyzoites.
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Patra S, Patil S, Klionsky DJ, Bhutia SK. Lysosome signaling in cell survival and programmed cell death for cellular homeostasis. J Cell Physiol 2023; 238:287-305. [PMID: 36502521 DOI: 10.1002/jcp.30928] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/06/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022]
Abstract
Recent developments in lysosome biology have transformed our view of lysosomes from static garbage disposals that can also act as suicide bags to decidedly dynamic multirole adaptive operators of cellular homeostasis. Lysosome-governed signaling pathways, proteins, and transcription factors equilibrate the rate of catabolism and anabolism (autophagy to lysosomal biogenesis and metabolite pool maintenance) by sensing cellular metabolic status. Lysosomes also interact with other organelles by establishing contact sites through which they exchange cellular contents. Lysosomal function is critically assessed by lysosomal positioning and motility for cellular adaptation. In this setting, mechanistic target of rapamycin kinase (MTOR) is the chief architect of lysosomal signaling to control cellular homeostasis. Notably, lysosomes can orchestrate explicit cell death mechanisms, such as autophagic cell death and lysosomal membrane permeabilization-associated regulated necrotic cell death, to maintain cellular homeostasis. These lines of evidence emphasize that the lysosomes serve as a central signaling hub for cellular homeostasis.
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Affiliation(s)
- Srimanta Patra
- Cancer and Cell Death Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Odisha, India
| | - Shankargouda Patil
- Division of Oral Pathology, Department of Maxillofacial Surgery and Diagnostic Sciences, College of Dentistry, Jazan University, Jazan, Saudi Arabia
| | - Daniel J Klionsky
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Sujit K Bhutia
- Cancer and Cell Death Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Odisha, India
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12
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Wang D, Wan X. Progress in research on the role of amino acid metabolic reprogramming in tumour therapy: A review. Biomed Pharmacother 2022; 156:113923. [DOI: 10.1016/j.biopha.2022.113923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/16/2022] [Accepted: 10/24/2022] [Indexed: 11/26/2022] Open
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13
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Meng D, Yang Q, Jeong MH, Curukovic A, Tiwary S, Melick CH, Lama-Sherpa TD, Wang H, Huerta-Rosario M, Urquhart G, Zacharias LG, Lewis C, DeBerardinis RJ, Jewell JL. SNAT7 regulates mTORC1 via macropinocytosis. Proc Natl Acad Sci U S A 2022; 119:e2123261119. [PMID: 35561222 PMCID: PMC9171778 DOI: 10.1073/pnas.2123261119] [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: 01/11/2022] [Accepted: 03/13/2022] [Indexed: 11/30/2022] Open
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) senses amino acids to control cell growth, metabolism, and autophagy. Some amino acids signal to mTORC1 through the Rag GTPase, whereas glutamine and asparagine activate mTORC1 through a Rag GTPase-independent pathway. Here, we show that the lysosomal glutamine and asparagine transporter SNAT7 activates mTORC1 after extracellular protein, such as albumin, is macropinocytosed. The N terminus of SNAT7 forms nutrient-sensitive interaction with mTORC1 and regulates mTORC1 activation independently of the Rag GTPases. Depletion of SNAT7 inhibits albumin-induced mTORC1 lysosomal localization and subsequent activation. Moreover, SNAT7 is essential to sustain KRAS-driven pancreatic cancer cell growth through mTORC1. Thus, SNAT7 links glutamine and asparagine signaling from extracellular protein to mTORC1 independently of the Rag GTPases and is required for macropinocytosis-mediated mTORC1 activation and pancreatic cancer cell growth.
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Affiliation(s)
- Delong Meng
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Qianmei Yang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mi-Hyeon Jeong
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Adna Curukovic
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Shweta Tiwary
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Chase H. Melick
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Tshering D. Lama-Sherpa
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Huanyu Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mariela Huerta-Rosario
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Greg Urquhart
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lauren G. Zacharias
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Cheryl Lewis
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Ralph J. DeBerardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jenna L. Jewell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
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14
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Wang J, Onogi Y, Krueger M, Oeckl J, Karlina R, Singh I, Hauck SM, Feederle R, Li Y, Ussar S. PAT2 regulates vATPase assembly and lysosomal acidification in brown adipocytes. Mol Metab 2022; 61:101508. [PMID: 35513259 PMCID: PMC9114668 DOI: 10.1016/j.molmet.2022.101508] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 04/26/2022] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE Brown adipocytes play a key role in maintaining body temperature as well as glucose and lipid homeostasis. However, brown adipocytes need to adapt their thermogenic activity and substrate utilization to changes in nutrient availability. Amongst the multiple factors influencing brown adipocyte activity, autophagy is an important regulatory element of thermogenic capacity and activity. Nevertheless, a specific sensing mechanism of extracellular amino acid availability linking autophagy to nutrient availability in brown adipocytes is unknown. METHODS To characterize the role of the amino acid transporter PAT2/SLC36A2 in brown adipocytes, loss or gain of function of PAT2 were studied with respect to differentiation, subcellular localization, lysosomal activity and autophagy. Activity of vATPase was evaluated by quenching of EGFP fused to LC3 or FITC-dextran loaded lysosomes in brown adipocytes upon amino acid starvation, whereas the effect of PAT2 on assembly of the vATPase was investigated by Native-PAGE. RESULTS We show that PAT2 translocates from the plasma membrane to the lysosome in response to amino acid withdrawal. Loss or overexpression of PAT2 impair lysosomal acidification and starvation induced S6K re-phosphorylation, as PAT2 facilitates the assembly of the lysosomal vATPase, by recruitment of the cytoplasmic V1 subunit to the lysosome. CONCLUSION PAT2 is an important sensor of extracellular amino acids and regulator of lysosomal acidification in brown adipocytes.
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Affiliation(s)
- Jiefu Wang
- RG Adipocytes & Metabolism, Institute for Diabetes & Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany
| | - Yasuhiro Onogi
- RG Adipocytes & Metabolism, Institute for Diabetes & Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany
| | - Martin Krueger
- Institute for Anatomy, University of Leipzig, 04103, Leipzig, Germany
| | - Josef Oeckl
- Chair for Molecular Nutritional Medicine TUM School for Life Sciences,Technical University Munich, Munich, Germany
| | - Ruth Karlina
- RG Adipocytes & Metabolism, Institute for Diabetes & Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany
| | - Inderjeet Singh
- RG Adipocytes & Metabolism, Institute for Diabetes & Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany
| | - Stefanie M Hauck
- German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany; Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, Neuherberg, Germany
| | - Regina Feederle
- German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany; Monoclonal Antibody Core Facility, Institute for Diabetes & Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany
| | - Yongguo Li
- Chair for Molecular Nutritional Medicine TUM School for Life Sciences,Technical University Munich, Munich, Germany
| | - Siegfried Ussar
- RG Adipocytes & Metabolism, Institute for Diabetes & Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany; German Center for Diabetes Research (DZD), 85764, Neuherberg, Germany; Department of Medicine, Technische Universität München, Munich, Germany.
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15
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Effects of Dietary Chlorogenic Acid Supplementation Derived from Lonicera macranthoides Hand-Mazz on Growth Performance, Free Amino Acid Profile, and Muscle Protein Synthesis in a Finishing Pig Model. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:6316611. [PMID: 35313639 PMCID: PMC8934221 DOI: 10.1155/2022/6316611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/10/2021] [Accepted: 02/21/2022] [Indexed: 12/22/2022]
Abstract
Chlorogenic acid (CGA), as one of the richest polyphenol compounds in nature, has broad applications in many fields due to its various biological properties. However, initial data on the effects of dietary CGA on protein synthesis and related basal metabolic activity has rarely been reported. The current study is aimed at (1) determining whether dietary CGA supplementation improves the growth performance and carcass traits, (2) assessing whether dietary CGA alters the free amino acid profile, and (3) verifying whether dietary CGA promotes muscle protein synthesis in finishing pigs. Thirty-two (Large × White × Landrace) finishing barrows with an average initial body weight of
kg were randomly allotted to 4 groups and fed diets supplemented with 0, 0.02%, 0.04%, and 0.08% CGA, respectively. The results indicated that, compared with the control group, dietary supplementation with 0.04% CGA slightly stimulated the growth performance of pigs, whereas no significant correlation was noted between the dietary CGA levels and animal growth (
). Furthermore, the carcass traits of pigs were improved by 0.04% dietary CGA (
). In addition, dietary CGA significantly improved the serum free amino acid profiles of pigs (
), while 0.04% dietary CGA promoted more amino acids to translocate to skeletal muscles (
). The relative mRNA expression levels of SNAT2 in both longissimus dorsi (LD) and biceps femoris (BF) muscles were augmented in the 0.02% and 0.04% groups (
), and the LAT1 mRNA expression in the BF muscle was elevated in the 0.02% group (
). We also found that dietary CGA supplementation at the levels of 0.04% or 0.08% promoted the expression of p-Akt and activated the mTOR-S6K1-4EBP1 axis in the LD muscle (
). Besides, the MAFbx mRNA abundance in the 0.02% and 0.04% groups was significantly lower (
). Our results revealed that dietary supplementation with CGA of 0.04% improved the free amino acid profile and enhanced muscle protein biosynthesis in the LD muscle in finishing pigs.
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16
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Current Methods to Unravel the Functional Properties of Lysosomal Ion Channels and Transporters. Cells 2022; 11:cells11060921. [PMID: 35326372 PMCID: PMC8946281 DOI: 10.3390/cells11060921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 02/07/2023] Open
Abstract
A distinct set of channels and transporters regulates the ion fluxes across the lysosomal membrane. Malfunctioning of these transport proteins and the resulting ionic imbalance is involved in various human diseases, such as lysosomal storage disorders, cancer, as well as metabolic and neurodegenerative diseases. As a consequence, these proteins have stimulated strong interest for their suitability as possible drug targets. A detailed functional characterization of many lysosomal channels and transporters is lacking, mainly due to technical difficulties in applying the standard patch-clamp technique to these small intracellular compartments. In this review, we focus on current methods used to unravel the functional properties of lysosomal ion channels and transporters, stressing their advantages and disadvantages and evaluating their fields of applicability.
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Nowosad A, Besson A. Lysosomes at the Crossroads of Cell Metabolism, Cell Cycle, and Stemness. Int J Mol Sci 2022; 23:ijms23042290. [PMID: 35216401 PMCID: PMC8879101 DOI: 10.3390/ijms23042290] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 02/07/2023] Open
Abstract
Initially described as lytic bodies due to their degradative and recycling functions, lysosomes play a critical role in metabolic adaptation to nutrient availability. More recently, the contribution of lysosomal proteins to cell signaling has been established, and lysosomes have emerged as signaling hubs that regulate diverse cellular processes, including cell proliferation and cell fate. Deciphering these signaling pathways has revealed an extensive crosstalk between the lysosomal and cell cycle machineries that is only beginning to be understood. Recent studies also indicate that a number of lysosomal proteins are involved in the regulation of embryonic and adult stem cell fate and identity. In this review, we will focus on the role of the lysosome as a signaling platform with an emphasis on its function in integrating nutrient sensing with proliferation and cell cycle progression, as well as in stemness-related features, such as self-renewal and quiescence.
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Affiliation(s)
- Ada Nowosad
- Molecular, Cellular and Developmental Biology Department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse, France;
- Department of Oncology, KULeuven, Laboratory for Molecular Cancer Biology, Center for Cancer Biology, VIB, 3000 Leuven, Belgium
| | - Arnaud Besson
- Molecular, Cellular and Developmental Biology Department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse, France;
- Correspondence: ; Tel.: +33-561558486
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18
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Zhang S, Lin X, Hou Q, Hu Z, Wang Y, Wang Z. Regulation of mTORC1 by amino acids in mammalian cells: A general picture of recent advances. ACTA ACUST UNITED AC 2021; 7:1009-1023. [PMID: 34738031 PMCID: PMC8536509 DOI: 10.1016/j.aninu.2021.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 05/13/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates various types of signal inputs, such as energy, growth factors, and amino acids to regulate cell growth and proliferation mainly through the 2 direct downstream targets, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and ribosomal protein S6 kinase 1 (S6K1). Most of the signal arms upstream of mTORC1 including energy status, stress signals, and growth factors converge on the tuberous sclerosis complex (TSC) - Ras homologue enriched in brain (Rheb) axis. Amino acids, however, are distinct from other signals and modulate mTORC1 using a unique pathway. In recent years, the transmission mechanism of amino acid signals upstream of mTORC1 has been gradually elucidated, and some sensors or signal transmission pathways for individual amino acids have also been discovered. With the help of these findings, we propose a general picture of recent advances, which demonstrates that various amino acids from lysosomes, cytoplasm, and Golgi are sensed by their respective sensors. These signals converge on mTORC1 and form a huge and complicated signal network with multiple synergies, antagonisms, and feedback mechanisms.
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Affiliation(s)
- Shizhe Zhang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Xueyan Lin
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Qiuling Hou
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Zhiyong Hu
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Yun Wang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Zhonghua Wang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
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Insights into the Interaction of Lysosomal Amino Acid Transporters SLC38A9 and SLC36A1 Involved in mTORC1 Signaling in C2C12 Cells. Biomolecules 2021; 11:biom11091314. [PMID: 34572527 PMCID: PMC8467208 DOI: 10.3390/biom11091314] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 08/28/2021] [Accepted: 08/31/2021] [Indexed: 11/16/2022] Open
Abstract
Amino acids are critical for mammalian target of rapamycin complex 1 (mTORC1) activation on the lysosomal surface. Amino acid transporters SLC38A9 and SLC36A1 are the members of the lysosomal amino acid sensing machinery that activates mTORC1. The current study aims to clarify the interaction of SLC38A9 and SLC36A1. Here, we discovered that leucine increased expressions of SLC38A9 and SLC36A1, leading to mTORC1 activation. SLC38A9 interacted with SLC36A1 and they enhanced each other's expression levels and locations on the lysosomal surface. Additionally, the interacting proteins of SLC38A9 in C2C12 cells were identified to participate in amino acid sensing mechanism, mTORC1 signaling pathway, and protein synthesis, which provided a resource for future investigations of skeletal muscle mass.
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20
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Zhang Q, Kuang M, An H, Zhang Y, Zhang K, Feng L, Zhang L, Cheng S. Peripheral blood transcriptome heterogeneity and prognostic potential in lung cancer revealed by RNA-Seq. J Cell Mol Med 2021; 25:8271-8284. [PMID: 34288383 PMCID: PMC8419186 DOI: 10.1111/jcmm.16773] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 05/22/2021] [Accepted: 06/21/2021] [Indexed: 12/24/2022] Open
Abstract
Understanding of the complex interaction between the peripheral immune system and lung cancer (LC) remains incomplete, limiting patient benefit. Here, we aimed to characterize the host peripheral immune response to LC and investigate its potential prognostic value. Bulk RNA-sequencing data of peripheral blood leucocytes (PBLs) from healthy volunteers and LC patients (n = 142) were analysed for characterization of host systemic immunity in LC. We observed broad blood transcriptome perturbations in LC patients that were heterogeneous, as two new subtypes were established independent of histology. Functionally, the heterogeneity between the two subtypes included dysregulation of diverse biological processes, such as the cell cycle, blood coagulation and inflammatory signalling pathways, together with the abundance and activity of blood cells, particularly lymphocytes and neutrophils, ultimately manifesting as differences in antitumour immune status. Based on these findings, a prognostic model composed of ten genes dysregulated in one LC subtype with relatively poor immune status was developed and validated in a Gene Expression Omnibus (GEO) data set (n = 108), helping to generate a prognostic nomogram. Collectively, our study provides novel and comprehensive insight into the heterogeneity of the host peripheral immune response to LC. The expression heterogeneity-based predictive model may help guide prognostic management for LC patients.
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Affiliation(s)
- Qi Zhang
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Manchao Kuang
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Haiyin An
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yajing Zhang
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Kai Zhang
- Department of Cancer Prevention, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lin Feng
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lei Zhang
- Department of Endoscopy ,National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shujun Cheng
- State Key Laboratory of Molecular Oncology, Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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21
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Amino Acids in Autophagy: Regulation and Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1332:51-66. [PMID: 34251638 DOI: 10.1007/978-3-030-74180-8_4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Autophagy is a dynamic process in which the eukaryotic cells break down intracellular components by lysosomal degradation. Under the normal condition, the basal level of autophagy removes damaged organelles, misfolded proteins, or protein aggregates to keep cells in a homeostatic condition. Deprivation of nutrients (e.g., removal of amino acids) stimulates autophagy activity, promoting lysosomal degradation and the recycling of cellular components for cell survival. Importantly, insulin and amino acids are two main inhibitors of autophagy. They both activate the mTOR complex 1 (mTORC1) signaling pathway to inhibit the autophagy upstream of the uncoordinated-51 like kinase 1/2 (ULK1/2) complex that triggers autophagosome formation. In particular, insulin activates mTORC1 via the PI3K class I-AKT pathway; while amino acids activate mTORC1 either through the PI3K class III (hVps34) pathway or through a variety of amino acid sensors located in the cytosol or lysosomal membrane. These amino acid sensors control the translocation of mTORC1 from the cytosol to the lysosomal surface where mTORC1 is activated by Rheb GTPase, therefore regulating autophagy and the lysosomal protein degradation.
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22
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Schmidt-Arras D, Rose-John S. Endosomes as Signaling Platforms for IL-6 Family Cytokine Receptors. Front Cell Dev Biol 2021; 9:688314. [PMID: 34141712 PMCID: PMC8204807 DOI: 10.3389/fcell.2021.688314] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 04/28/2021] [Indexed: 12/12/2022] Open
Abstract
Interleukin-6 (IL-6) is the name-giving cytokine of a family of eleven members, including IL-6, CNTF, LIF, and IL-27. IL-6 was first recognized as a B-cell stimulating factor but we now know that the cytokine plays a pivotal role in the orchestration of inflammatory processes as well as in inflammation associated cancer. Moreover, IL-6 is involved in metabolic regulation and it has been shown to be involved in major neural activities such as neuroprotection, which can help to repair and to reduce brain damage. Receptor complexes of all members formed at the plasma membrane contain one or two molecules of the signaling receptor subunit GP130 and the mechanisms of signal transduction are well understood. IL-6 type cytokines can also signal from endomembranes, in particular the endosome, and situations have been reported in which endocytosis of receptor complexes are a prerequisite of intracellular signaling. Moreover, pathogenic GP130 variants were shown to interfere with spatial activation of downstream signals. We here summarize the molecular mechanisms underlying spatial regulation of IL-6 family cytokine signaling and discuss its relevance for pathogenic processes.
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Affiliation(s)
- Dirk Schmidt-Arras
- Institute of Biochemistry, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Stefan Rose-John
- Institute of Biochemistry, Christian-Albrechts-University Kiel, Kiel, Germany
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23
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Roberson PA, Mobley CB, Romero MA, Haun CT, Osburn SC, Mumford PW, Vann CG, Greer RA, Ferrando AA, Roberts MD. LAT1 Protein Content Increases Following 12 Weeks of Resistance Exercise Training in Human Skeletal Muscle. Front Nutr 2021; 7:628405. [PMID: 33521042 PMCID: PMC7840583 DOI: 10.3389/fnut.2020.628405] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 12/11/2020] [Indexed: 12/24/2022] Open
Abstract
Introduction: Amino acid transporters are essential for cellular amino acid transport and promoting protein synthesis. While previous literature has demonstrated the association of amino acid transporters and protein synthesis following acute resistance exercise and amino acid supplementation, the chronic effect of resistance exercise and supplementation on amino acid transporters is unknown. The purpose herein was to determine if amino acid transporters and amino acid metabolic enzymes were related to skeletal muscle hypertrophy following resistance exercise training with different nutritional supplementation strategies. Methods: 43 college-aged males were separated into a maltodextrin placebo (PLA, n = 12), leucine (LEU, n = 14), or whey protein concentrate (WPC, n = 17) group and underwent 12 weeks of total-body resistance exercise training. Each group's supplement was standardized for total energy and fat, and LEU and WPC supplements were standardized for total leucine (6 g/d). Skeletal muscle biopsies were obtained prior to training and ~72 h following each subject's last training session. Results: All groups increased type I and II fiber cross-sectional area (fCSA) following training (p < 0.050). LAT1 protein increased following training (p < 0.001) and increased more in PLA than LEU and WPC (p < 0.050). BCKDHα protein increased and ATF4 protein decreased following training (p < 0.001). Immunohistochemistry indicated total LAT1/fiber, but not membrane LAT1/fiber, increased with training (p = 0.003). Utilizing all groups, the change in ATF4 protein, but no other marker, trended to correlate with the change in fCSA (r = 0.314; p = 0.055); however, when regression analysis was used to delineate groups, the change in ATF4 protein best predicted the change in fCSA only in LEU (r 2 = 0.322; p = 0.043). In C2C12 myoblasts, LAT1 protein overexpression caused a paradoxical decrease in protein synthesis levels (p = 0.002) and decrease in BCKDHα protein (p = 0.001). Conclusions: Amino acid transporters and metabolic enzymes are affected by resistance exercise training, but do not appear to dictate muscle fiber hypertrophy. In fact, overexpression of LAT1 in vitro decreased protein synthesis.
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Affiliation(s)
- Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - C Brooks Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Rory A Greer
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Arny A Ferrando
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AK, United States
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24
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Nesterov SV, Yaguzhinsky LS, Podoprigora GI, Nartsissov YR. Amino Acids as Regulators of Cell Metabolism. BIOCHEMISTRY (MOSCOW) 2021; 85:393-408. [PMID: 32569548 DOI: 10.1134/s000629792004001x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In this review, we discuss the principles of regulation and synchronization of metabolic processes in mammalian cells using a two-component model of cell metabolism consisting of a controlling signaling system that regulates major enzymatic cascades and executive metabolic system that directly performs biosynthetic reactions. This approach has allowed us to distinguish two transitional metabolic states (from catabolism to anabolism and vice versa) accompanied by major rearrangements in the signaling system. The signaling system of natural amino acids was selected, because amino acids are involved in both signaling and executive metabolic subsystems of general cell metabolism. We have developed a graphical representation of metabolic events that allowed us to demonstrate the succession of processes occurring in both metabolic subsystems during complete metabolic cycle in a non-dividing cell. An important revealed feature of the amino acid signaling system is that the signaling properties of amino acid are determined not only by their molecular structure, but also by the location within the cell. Four major signaling groups of amino acids have been identified that localize to lysosomes, mitochondria, cytosol, and extracellular space adjacent to the plasma membrane. Although these amino acids groups are similar in the composition, they have different receptors. We also proposed a scheme for the metabolism regulation by amino acids signaling that can serve as a basis for developing more complete spatio-temporal picture of metabolic regulation involving a wide variety of intracellular signaling cascades.
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Affiliation(s)
- S V Nesterov
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - L S Yaguzhinsky
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia. .,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - G I Podoprigora
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia
| | - Ya R Nartsissov
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia
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25
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Saric A, Freeman SA. Endomembrane Tension and Trafficking. Front Cell Dev Biol 2021; 8:611326. [PMID: 33490077 PMCID: PMC7820182 DOI: 10.3389/fcell.2020.611326] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/09/2020] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic cells employ diverse uptake mechanisms depending on their specialized functions. While such mechanisms vary widely in their defining criteria: scale, molecular machinery utilized, cargo selection, and cargo destination, to name a few, they all result in the internalization of extracellular solutes and fluid into membrane-bound endosomes. Upon scission from the plasma membrane, this compartment is immediately subjected to extensive remodeling which involves tubulation and vesiculation/budding of the limiting endomembrane. This is followed by a maturation process involving concomitant retrograde transport by microtubule-based motors and graded fusion with late endosomes and lysosomes, organelles that support the degradation of the internalized content. Here we review an important determinant for sorting and trafficking in early endosomes and in lysosomes; the control of tension on the endomembrane. Remodeling of endomembranes is opposed by high tension (caused by high hydrostatic pressure) and supported by the relief of tension. We describe how the timely and coordinated efflux of major solutes along the endocytic pathway affords the cell control over such tension. The channels and transporters that expel the smallest components of the ingested medium from the early endocytic fluid are described in detail as these systems are thought to enable endomembrane deformation by curvature-sensing/generating coat proteins. We also review similar considerations for the lysosome where resident hydrolases liberate building blocks from luminal macromolecules and transporters flux these organic solutes to orchestrate trafficking events. How the cell directs organellar trafficking based on the luminal contents of organelles of the endocytic pathway is not well-understood, however, we propose that the control over membrane tension by solute transport constitutes one means for this to ensue.
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Affiliation(s)
- Amra Saric
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Center for Research and Learning, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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26
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Cormerais Y, Vučetić M, Parks SK, Pouyssegur J. Amino Acid Transporters Are a Vital Focal Point in the Control of mTORC1 Signaling and Cancer. Int J Mol Sci 2020; 22:E23. [PMID: 33375025 PMCID: PMC7792758 DOI: 10.3390/ijms22010023] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/14/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates signals from growth factors and nutrients to control biosynthetic processes, including protein, lipid, and nucleic acid synthesis. Dysregulation in the mTORC1 network underlies a wide array of pathological states, including metabolic diseases, neurological disorders, and cancer. Tumor cells are characterized by uncontrolled growth and proliferation due to a reduced dependency on exogenous growth factors. The genetic events underlying this property, such as mutations in the PI3K-Akt and Ras-Erk signaling networks, lead to constitutive activation of mTORC1 in nearly all human cancer lineages. Aberrant activation of mTORC1 has been shown to play a key role for both anabolic tumor growth and resistance to targeted therapeutics. While displaying a growth factor-independent mTORC1 activity and proliferation, tumors cells remain dependent on exogenous nutrients such as amino acids (AAs). AAs are an essential class of nutrients that are obligatory for the survival of any cell. Known as the building blocks of proteins, AAs also act as essential metabolites for numerous biosynthetic processes such as fatty acids, membrane lipids and nucleotides synthesis, as well as for maintaining redox homeostasis. In most tumor types, mTORC1 activity is particularly sensitive to intracellular AA levels. This dependency, therefore, creates a targetable vulnerability point as cancer cells become dependent on AA transporters to sustain their homeostasis. The following review will discuss the role of AA transporters for mTORC1 signaling in cancer cells and their potential as therapeutic drug targets.
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Affiliation(s)
- Yann Cormerais
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Milica Vučetić
- Department of Medical Biology, Centre Scientifique de Monaco (CSM), 98000 Monaco, Monaco; (M.V.); (S.K.P.)
| | - Scott K. Parks
- Department of Medical Biology, Centre Scientifique de Monaco (CSM), 98000 Monaco, Monaco; (M.V.); (S.K.P.)
| | - Jacques Pouyssegur
- Department of Medical Biology, Centre Scientifique de Monaco (CSM), 98000 Monaco, Monaco; (M.V.); (S.K.P.)
- CNRS, INSERM, Centre A. Lacassagne, Faculté de Médecine (IRCAN), Université Côte d’Azur, 06107 Nice, France
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27
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Baliou S, Kyriakopoulos AM, Goulielmaki M, Panayiotidis MI, Spandidos DA, Zoumpourlis V. Significance of taurine transporter (TauT) in homeostasis and its layers of regulation (Review). Mol Med Rep 2020; 22:2163-2173. [PMID: 32705197 PMCID: PMC7411481 DOI: 10.3892/mmr.2020.11321] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/09/2020] [Indexed: 11/05/2022] Open
Abstract
Taurine (2‑aminoethanesulfonic acid) contributes to homeostasis, mainly through its antioxidant and osmoregulatory properties. Taurine's influx and efflux are mainly mediated through the ubiquitous expression of the sodium/chloride‑dependent taurine transporter, located on the plasma membrane. The significance of the taurine transporter has been shown in various organ malfunctions in taurine‑transporter‑null mice. The taurine transporter differentially responds to various cellular stimuli including ionic environment, electrochemical charge, and pH changes. The renal system has been used as a model to evaluate the factors that significantly determine the regulation of taurine transporter regulation.
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Affiliation(s)
- Stella Baliou
- National Hellenic Research Foundation, 11635 Athens, Greece
| | | | | | - Michalis I Panayiotidis
- Department of Electron Microscopy and Molecular Pathology, The Cyprus Institute of Neurology and Genetics, 2371 Nicosia, Cyprus
| | - Demetrios A Spandidos
- Laboratory of Clinical Virology, Medical School, University of Crete, 71003 Heraklion, Greece
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28
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Carroll B. Spatial regulation of mTORC1 signalling: Beyond the Rag GTPases. Semin Cell Dev Biol 2020; 107:103-111. [PMID: 32122730 DOI: 10.1016/j.semcdb.2020.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/17/2020] [Accepted: 02/20/2020] [Indexed: 12/15/2022]
Abstract
The mechanistic (or mammalian) Target of Rapamycin Complex 1 (mTORC1) is a central regulator of cell growth and metabolism. By integrating mitogenic signals, mTORC1-dependent phosphorylation of substrates dictates the balance between anabolic, pro-growth and catabolic, recycling processes in the cell. The discovery that amino acids activate mTORC1 by promoting its translocation to the lysosome was a fundamental advance in the understanding of mTORC1 signalling. It has since become clear that the lysosome-cytoplasm shuttling of mTORC1 represents just one layer of spatial control of this signalling pathway. This review will focus on exploring the subcellular localisation of mTORC1 and its regulators to multiple sites within the cell. We will discuss how these spatially distinct regions such as endoplasmic reticulum, plasma membrane and the endosomal pathway co-operate to transduce nutrient availability to mTORC1, allowing for tight control of cell growth.
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Affiliation(s)
- Bernadette Carroll
- School of Biochemistry, Biomedical Sciences Building, University Walk, Bristol, BS8, United Kingdom.
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29
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Yoshida A, Bu Y, Qie S, Wrangle J, Camp ER, Hazard ES, Hardiman G, de Leeuw R, Knudsen KE, Diehl JA. SLC36A1-mTORC1 signaling drives acquired resistance to CDK4/6 inhibitors. SCIENCE ADVANCES 2019; 5:eaax6352. [PMID: 31555743 PMCID: PMC6750908 DOI: 10.1126/sciadv.aax6352] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/21/2019] [Indexed: 06/03/2023]
Abstract
The cyclin-dependent kinase 4/6 (CDK4/6) kinase is dysregulated in melanoma, highlighting it as a potential therapeutic target. CDK4/6 inhibitors are being evaluated in trials for melanoma and additional cancers. While beneficial, resistance to therapy is a concern, and the molecular mechanisms of such resistance remain undefined. We demonstrate that reactivation of mammalian target of rapamycin 1 (mTORC1) signaling through increased expression of the amino acid transporter, solute carrier family 36 member 1 (SLC36A1), drives resistance to CDK4/6 inhibitors. Increased expression of SLC36A1 reflects two distinct mechanisms: (i) Rb loss, which drives SLC36A1 via reduced suppression of E2f; (ii) fragile X mental retardation syndrome-associated protein 1 overexpression, which promotes SLC36A1 translation and subsequently mTORC1. Last, we demonstrate that a combination of a CDK4/6 inhibitor with an mTORC1 inhibitor has increased therapeutic efficacy in vivo, providing an important avenue for improved therapeutic intervention in aggressive melanoma.
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Affiliation(s)
- Akihiro Yoshida
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Yiwen Bu
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Shuo Qie
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - John Wrangle
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
| | - E. Ramsay Camp
- Department of Surgery, Medical University of South Carolina, Charleston, SC 29425, USA
| | - E. Starr Hazard
- Center for Genomic Medicine Bioinformatics, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Gary Hardiman
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
- Center for Genomic Medicine Bioinformatics, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Renée de Leeuw
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Karen E. Knudsen
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - J. Alan Diehl
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
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30
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Kvainickas A, Nägele H, Qi W, Dokládal L, Jimenez-Orgaz A, Stehl L, Gangurde D, Zhao Q, Hu Z, Dengjel J, De Virgilio C, Baumeister R, Steinberg F. Retromer and TBC1D5 maintain late endosomal RAB7 domains to enable amino acid-induced mTORC1 signaling. J Cell Biol 2019; 218:3019-3038. [PMID: 31431476 PMCID: PMC6719456 DOI: 10.1083/jcb.201812110] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/30/2019] [Accepted: 07/08/2019] [Indexed: 02/07/2023] Open
Abstract
Retromer is an evolutionarily conserved multiprotein complex that orchestrates the endocytic recycling of integral membrane proteins. Here, we demonstrate that retromer is also required to maintain lysosomal amino acid signaling through mTORC1 across species. Without retromer, amino acids no longer stimulate mTORC1 translocation to the lysosomal membrane, which leads to a loss of mTORC1 activity and increased induction of autophagy. Mechanistically, we show that its effect on mTORC1 activity is not linked to retromer's role in the recycling of transmembrane proteins. Instead, retromer cooperates with the RAB7-GAP TBC1D5 to restrict late endosomal RAB7 into microdomains that are spatially separated from the amino acid-sensing domains. Upon loss of retromer, RAB7 expands into the ragulator-decorated amino acid-sensing domains and interferes with RAG-GTPase and mTORC1 recruitment. Depletion of retromer in Caenorhabditis elegans reduces mTORC1 signaling and extends the lifespan of the worms, confirming an evolutionarily conserved and unexpected role for retromer in the regulation of mTORC1 activity and longevity.
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Affiliation(s)
- Arunas Kvainickas
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
| | - Heike Nägele
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
| | - Wenjing Qi
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Ladislav Dokládal
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Ana Jimenez-Orgaz
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
| | - Luca Stehl
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
| | - Dipak Gangurde
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Qian Zhao
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Zehan Hu
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jörn Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | - Ralf Baumeister
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Florian Steinberg
- Center for Biological Systems Analysis, University of Freiburg, Freiburg, Germany
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31
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Follo C, Vidoni C, Morani F, Ferraresi A, Seca C, Isidoro C. Amino acid response by Halofuginone in Cancer cells triggers autophagy through proteasome degradation of mTOR. Cell Commun Signal 2019; 17:39. [PMID: 31046771 PMCID: PMC6498594 DOI: 10.1186/s12964-019-0354-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/16/2019] [Indexed: 02/07/2023] Open
Abstract
Background In the event of amino acid starvation, the cell activates two main protective pathways: Amino Acid starvation Response (AAR), to inhibit global translation, and autophagy, to recover the essential substrates from degradation of redundant self-components. Whether and how AAR and autophagy (ATG) are cross-regulated and at which point the two regulatory pathways intersect remain unknown. Here, we provide experimental evidence that the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) specifically located at the lysosome level links the AAR with the autophagy pathway. Methods As an inducer of the AAR, we used halofuginone (HF), an alkaloid that binds to the prolyl-tRNA synthetase thus mimicking the unavailability of proline (PRO). Induction of AAR was determined assessing the phosphorylation of the eukaryotic translation initiation factor (eIF) 2α. Autophagy was monitored by assessing the processing and accumulation of microtubule-associated protein 1 light chain 3 isoform B (LC3B) and sequestosome-1 (p62/SQSTM1) levels. The activity of mTORC1 was monitored through assessment of the phosphorylation of mTOR, (rp)S6 and 4E-BP1. Global protein synthesis was determined by puromycin incorporation assay. mTORC1 presence on the membrane of the lysosomes was monitored by cell fractionation and mTOR expression was determined by immunoblotting. Results In three different types of human cancer cells (thyroid cancer WRO cells, ovarian cancer OAW-42 cells, and breast cancer MCF-7 cells), HF induced both the AAR and the autophagy pathways time-dependently. In WRO cells, which showed the strongest induction of autophagy and of AAR, global protein synthesis was little if any affected. Consistently, 4E-BP1 and (rp)S6 were phosphorylated. Concomitantly, mTOR expression and activation declined along with its detachment from the lysosomes and its degradation by the proteasome, and with the nuclear translocation of transcription factor EB (TFEB), a transcription factor of many ATG genes. The extra supplementation of proline rescued all these effects. Conclusions We demonstrate that the AAR and autophagy are mechanistically linked at the level of mTORC1, and that the lysosome is the central hub of the cross-talk between these two metabolic stress responses. ![]()
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Affiliation(s)
- Carlo Follo
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy.,Present address: Zuckerberg San Francisco General Hospital and Trauma Center, University of California San Francisco, San Francisco, CA, 94110, USA
| | - Chiara Vidoni
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Federica Morani
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Alessandra Ferraresi
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Christian Seca
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Ciro Isidoro
- Laboratory of Molecular Pathology, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy. .,Dipartimento di Scienze della Salute, Università "A. Avogadro", Via P. Solaroli 17, 28100, Novara, Italy.
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32
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Kawano-Kawada M, Kakinuma Y, Sekito T. Transport of Amino Acids across the Vacuolar Membrane of Yeast: Its Mechanism and Physiological Role. Biol Pharm Bull 2019; 41:1496-1501. [PMID: 30270317 DOI: 10.1248/bpb.b18-00165] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In yeast cells growing under nutrient-rich condition approximately 50% of total amino acids are accumulated in the vacuoles; however, the composition of amino acids in the cytosol and in the vacuoles is quite different. The vacuoles, like lysosomes, degrade proteins transported into their lumen and produce amino acids. These amino acids should be quickly excreted to the cytosol under nutrient starvation condition and recycled for de novo protein synthesis. These suggest that specific machineries that transport amino acids into and out of the vacuoles operate at the vacuolar membrane. Several families of transporter involved in the vacuolar compartmentalization of amino acids have been identified and characterized using budding yeast Saccharomyces cerevisiae. In this review, we describe the vacuolar amino acid transporters identified so far and introduce recent findings on their activity and physiological function.
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Affiliation(s)
- Miyuki Kawano-Kawada
- Department of Biosicence, Graduate School of Agriculture, Ehime University.,Advanced Research Support Center (ADRES), Ehime University
| | - Yoshimi Kakinuma
- Department of Biosicence, Graduate School of Agriculture, Ehime University
| | - Takayuki Sekito
- Department of Biosicence, Graduate School of Agriculture, Ehime University
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33
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Lunova M, Smolková B, Lynnyk A, Uzhytchak M, Jirsa M, Kubinová Š, Dejneka A, Lunov O. Targeting the mTOR Signaling Pathway Utilizing Nanoparticles: A Critical Overview. Cancers (Basel) 2019; 11:E82. [PMID: 30642006 PMCID: PMC6356373 DOI: 10.3390/cancers11010082] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 12/21/2018] [Accepted: 01/05/2019] [Indexed: 12/21/2022] Open
Abstract
Proteins of the mammalian target of rapamycin (mTOR) signaling axis are overexpressed or mutated in cancers. However, clinical inhibition of mTOR signaling as a therapeutic strategy in oncology shows rather limited progress. Nanoparticle-based mTOR targeted therapy proposes an attractive therapeutic option for various types of cancers. Along with the progress in the biomedical applications of nanoparticles, we start to realize the challenges and opportunities that lie ahead. Here, we critically analyze the current literature on the modulation of mTOR activity by nanoparticles, demonstrate the complexity of cellular responses to functionalized nanoparticles, and underline challenges lying in the identification of the molecular mechanisms of mTOR signaling affected by nanoparticles. We propose the idea that subcytotoxic doses of nanoparticles could be relevant for the induction of subcellular structural changes with possible involvement of mTORC1 signaling. The evaluation of the mechanisms and therapeutic effects of nanoparticle-based mTOR modulation will provide fundamental knowledge which could help in developing safe and efficient nano-therapeutics.
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Affiliation(s)
- Mariia Lunova
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
- Institute for Clinical & Experimental Medicine (IKEM), Prague, 140 21, Czech Republic.
| | - Barbora Smolková
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
| | - Anna Lynnyk
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
| | - Mariia Uzhytchak
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
| | - Milan Jirsa
- Institute for Clinical & Experimental Medicine (IKEM), Prague, 140 21, Czech Republic.
| | - Šárka Kubinová
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
- Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, 14220, Czech Republic.
| | - Alexandr Dejneka
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
| | - Oleg Lunov
- Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
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34
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Zhao L, Ji X, Zhang X, Li L, Jin Y, Liu W. FLCN is a novel Rab11A-interacting protein that is involved in the Rab11A-mediated recycling transport. J Cell Sci 2018; 131:jcs.218792. [PMID: 30446510 DOI: 10.1242/jcs.218792] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 11/02/2018] [Indexed: 12/23/2022] Open
Abstract
The Birt-Hogg-Dubé (BHD) syndrome related protein FLCN has recently been implicated in the vesicular trafficking processes by interacting with several Rab family GTPases. In the previous studies, we have shown that FLCN could inhibit the binding of overexpressed PAT1, which is a membrane-bound amino acid transporter, to the lysosome in human embryonic kidney 293 cells. This tends to stabilize the lysosomal amino acid pool that is a critical signal to activate the mTORC1 signaling pathway. However, the mechanisms of FLCN during this process remain unexplored. Here we report that FLCN can bind through its C-terminal DENN-like domain to the recycling transport regulator, Rab11A. Suppression of either Rab11A or FLCN facilitated the localization of the overexpressed PAT1 to the lysosome and inhibited its targeting on the plasma membrane. As a consequence, the mTORC1 was down-regulated. The in vitro GEF activity assay does not support FLCN modifies the Rab11A activity directly. Instead, we found FLCN promoted the loading of PAT1 on Rab11A. Our data uncover a function of FLCN in the Rab11A-mediated recycling pathway and might provide new clues to understand BHD.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Lingling Zhao
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China 712100
| | - Xin Ji
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China 712100
| | - Xiangxiang Zhang
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China 712100
| | - Lin Li
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China 712100
| | - Yaping Jin
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China 712100
| | - Wei Liu
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China 712100
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35
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Dato S, Hoxha E, Crocco P, Iannone F, Passarino G, Rose G. Amino acids and amino acid sensing: implication for aging and diseases. Biogerontology 2018; 20:17-31. [DOI: 10.1007/s10522-018-9770-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 09/16/2018] [Indexed: 11/30/2022]
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36
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Zhao L, Zhang X, Ji X, Jin Y, Liu W. The amino acid transporter PAT1 regulates mTORC1 in a nutrient-sensitive manner that requires its transport activity. Cell Signal 2018; 53:59-67. [PMID: 30253187 DOI: 10.1016/j.cellsig.2018.09.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 09/17/2018] [Accepted: 09/21/2018] [Indexed: 10/28/2022]
Abstract
The proton-coupled amino acid transporter PAT1 has been postulated to regulate the amino acid-stimulated mTORC1 through two different mechanisms, either it activates mTORC1 by sensing and transducing the lysosomal amino acid signal to mTORC1, or it inhibits mTORC1 by decreasing the signal level, as increased PAT1 has been shown to either activate or inactivate mTORC1 in the human embryonic kidney HEK293 cells. The current study aims to clarify the cause of these controversial observations, which is promoted by the recent discovery that the lysosomal PAT1 can be induced by starvation. Here, we show that under the normal culture condition, overexpression of PAT1 did not apparently change the mTORC1 activity in the fast proliferating cells. However when these cells were synchronized by starvation, followed by nutrient replenishment for a short period of time, the mTORC1 activity was decreased by PAT1 overexpression; if the nutrient stimulation lasted for longer time, the mTORC1 activities could be recovered in the PAT1-overexpressing cells. In addition, we showed the starvation-induced lysosomal PAT1 was gradually decreased during the nutrient replenishment. These results reveal that the influence of PAT1 on mTORC1 seems to be affected by the nutrient condition and the level of lysosomal PAT1. We further demonstrate that suppressing the transport activity of PAT1 abolished its inhibitory effect on mTORC1. Our data support a mechanism that PAT1 can negatively regulate mTORC1 by controlling the cellular nutrient signal level.
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Affiliation(s)
- Lingling Zhao
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xiangxiang Zhang
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xin Ji
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Yaping Jin
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Wei Liu
- Key Laboratory of Animal Biotechnology, the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China.
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Fan SJ, Goberdhan DCI. PATs and SNATs: Amino Acid Sensors in Disguise. Front Pharmacol 2018; 9:640. [PMID: 29971004 PMCID: PMC6018406 DOI: 10.3389/fphar.2018.00640] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 05/29/2018] [Indexed: 11/30/2022] Open
Abstract
Solute Carriers (SLCs) are involved in the transport of substances across lipid bilayers, including nutrients like amino acids. Amino acids increase the activity of the microenvironmental sensor mechanistic Target of Rapamycin Complex 1 (mTORC1) to promote cellular growth and anabolic processes. They can be brought in to cells by a wide range of SLCs including the closely related Proton-assisted Amino acid Transporter (PAT or SLC36) and Sodium-coupled Neutral Amino acid Transporter (SNAT or SLC38) families. More than a decade ago, the first evidence emerged that members of the PAT family can act as amino acid-stimulated receptors, or so-called "transceptors," connecting amino acids to mTORC1 activation. Since then, further studies in human cell models have suggested that other PAT and SNAT family members, which share significant homology within their transmembrane domains, can act as transceptors. A paradigm shift has also led to the PATs and SNATs at the surface of multiple intracellular compartments being linked to the recruitment and activation of different pools of mTORC1. Much focus has been on late endosomes and lysosomes as mTORC1 regulatory hubs, but more recently a Golgi-localized PAT was shown to be required for mTORC1 activation. PATs and SNATs can also traffic between the cell surface and intracellular compartments, with regulation of this movement providing a means of controlling their mTORC1 regulatory activity. These emerging features of PAT and SNAT amino acid sensors, including the transceptor mechanism, have implications for the pharmacological inhibition of mTORC1 and new therapeutic interventions.
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Affiliation(s)
| | - Deborah C. I. Goberdhan
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Luthra S, Chandran U, Diergaarde B, Becich M, Lee AV, Neumann CA. Expression of reactive species related genes is associated with patient survival in luminal B breast cancer. Free Radic Biol Med 2018; 120:170-180. [PMID: 29545070 PMCID: PMC5940524 DOI: 10.1016/j.freeradbiomed.2018.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 01/01/2023]
Abstract
Increased reactive species (RS; reactive oxygen and nitrogen species) are a byproduct of both enzymatic and non-enzymatic systems, and critical in cancer development, including breast tumorigenesis. To investigate the role of RS-related genes in breast cancer, expression levels of the most common annotated genes involved in regulating cellular RS levels and proteins that are substrates of RS in specific subtypes of breast cancer 9 were evaluated using public data bases. Based on the premise that increased RS promote tumor formation, and breast cancer subtypes vary in aggressiveness, we hypothesized that specific RS gene expression signatures are associated with breast cancer aggressiveness and patient survival. We identified a group of genes (GSTK1, PRDX2, PRDX3 and SLC36A1) that differentiate Luminal B tumors in two clusters and predict survival of patients with Luminal B breast cancers. Furthermore, network analyses of these four genes revealed an overlap of known LumB related pathways with those of RS-related signaling, which included regulation of M-phase and mitochondrial functions.
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Affiliation(s)
- Soumya Luthra
- Department of Biomedical Informatics, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Uma Chandran
- Department of Biomedical Informatics, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Brenda Diergaarde
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Michael Becich
- Department of Biomedical Informatics, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Adrian V Lee
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA; Women's Cancer Research Center, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA; Magee-Women's Research Institute, Magee-Women's Research Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
| | - Carola A Neumann
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA; Women's Cancer Research Center, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA; Magee-Women's Research Institute, Magee-Women's Research Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA.
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Rentero C, Blanco-Muñoz P, Meneses-Salas E, Grewal T, Enrich C. Annexins-Coordinators of Cholesterol Homeostasis in Endocytic Pathways. Int J Mol Sci 2018; 19:E1444. [PMID: 29757220 PMCID: PMC5983649 DOI: 10.3390/ijms19051444] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 02/07/2023] Open
Abstract
The spatiotemporal regulation of calcium (Ca2+) storage in late endosomes (LE) and lysosomes (Lys) is increasingly recognized to influence a variety of membrane trafficking events, including endocytosis, exocytosis, and autophagy. Alterations in Ca2+ homeostasis within the LE/Lys compartment are implicated in human diseases, ranging from lysosomal storage diseases (LSDs) to neurodegeneration and cancer, and they correlate with changes in the membrane binding behaviour of Ca2+-binding proteins. This also includes Annexins (AnxA), which is a family of Ca2+-binding proteins participating in membrane traffic and tethering, microdomain organization, cytoskeleton interactions, Ca2+ signalling, and LE/Lys positioning. Although our knowledge regarding the way Annexins contribute to LE/Lys functions is still incomplete, recruitment of Annexins to LE/Lys is greatly influenced by the availability of Annexin bindings sites, including acidic phospholipids, such as phosphatidylserine (PS) and phosphatidic acid (PA), cholesterol, and phosphatidylinositol (4,5)-bisphosphate (PIP2). Moreover, the cytosolic portion of LE/Lys membrane proteins may also, directly or indirectly, determine the recruitment of Annexins to LE. Strikingly, within LE/Lys, AnxA1, A2, A6, and A8 differentially contribute to cholesterol transport along the endocytic route, in particular, cholesterol transfer between LE and other compartments, positioning Annexins at the centre of major pathways mediating cellular cholesterol homeostasis. Underlying mechanisms include the formation of membrane contact sites (MCS) and intraluminal vesicles (ILV), as well as the modulation of LE-cholesterol transporter activity. In this review, we will summarize the current understanding how Annexins contribute to influence LE/Lys membrane transport and associated functions.
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Affiliation(s)
- Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
| | - Patricia Blanco-Muñoz
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
| | - Elsa Meneses-Salas
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
| | - Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia.
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
- Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain.
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40
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Steyfkens F, Zhang Z, Van Zeebroeck G, Thevelein JM. Multiple Transceptors for Macro- and Micro-Nutrients Control Diverse Cellular Properties Through the PKA Pathway in Yeast: A Paradigm for the Rapidly Expanding World of Eukaryotic Nutrient Transceptors Up to Those in Human Cells. Front Pharmacol 2018; 9:191. [PMID: 29662449 PMCID: PMC5890159 DOI: 10.3389/fphar.2018.00191] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 02/20/2018] [Indexed: 12/17/2022] Open
Abstract
The nutrient composition of the medium has dramatic effects on many cellular properties in the yeast Saccharomyces cerevisiae. In addition to the well-known specific responses to starvation for an essential nutrient, like nitrogen or phosphate, the presence of fermentable sugar or a respirative carbon source leads to predominance of fermentation or respiration, respectively. Fermenting and respiring cells also show strong differences in other properties, like storage carbohydrate levels, general stress tolerance and cellular growth rate. However, the main glucose repression pathway, which controls the switch between respiration and fermentation, is not involved in control of these properties. They are controlled by the protein kinase A (PKA) pathway. Addition of glucose to respiring yeast cells triggers cAMP synthesis, activation of PKA and rapid modification of its targets, like storage carbohydrate levels, general stress tolerance and growth rate. However, starvation of fermenting cells in a glucose medium for any essential macro- or micro-nutrient counteracts this effect, leading to downregulation of PKA and its targets concomitant with growth arrest and entrance into G0. Re-addition of the lacking nutrient triggers rapid activation of the PKA pathway, without involvement of cAMP as second messenger. Investigation of the sensing mechanism has revealed that the specific high-affinity nutrient transporter(s) induced during starvation function as transporter-receptors or transceptors for rapid activation of PKA upon re-addition of the missing substrate. In this way, transceptors have been identified for amino acids, ammonium, phosphate, sulfate, iron, and zinc. We propose a hypothesis for regulation of PKA activity by nutrient transceptors to serve as a conceptual framework for future experimentation. Many properties of transceptors appear to be similar to those of classical receptors and nutrient transceptors may constitute intermediate forms in the development of receptors from nutrient transporters during evolution. The nutrient-sensing transceptor system in yeast for activation of the PKA pathway has served as a paradigm for similar studies on candidate nutrient transceptors in other eukaryotes and we succinctly discuss the many examples of transceptors that have already been documented in other yeast species, filamentous fungi, plants, and animals, including the examples in human cells.
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Affiliation(s)
- Fenella Steyfkens
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium.,Center for Microbiology, VIB, Flanders, Belgium
| | - Zhiqiang Zhang
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium.,Center for Microbiology, VIB, Flanders, Belgium
| | - Griet Van Zeebroeck
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium.,Center for Microbiology, VIB, Flanders, Belgium
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium.,Center for Microbiology, VIB, Flanders, Belgium
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Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) coordinates cellular growth and metabolism with environmental inputs to ensure that cells grow only under favourable conditions. When active, mTORC1 stimulates biosynthetic pathways including protein, lipid and nucleotide synthesis and inhibits cellular catabolism through repression of the autophagic pathway, thereby promoting cell growth and proliferation. The recruitment of mTORC1 to the lysosomal surface has been shown to be essential for its activation. This finding has significantly enhanced our knowledge of mTORC1 regulation and has focused the attention of the field on the lysosome as a signalling hub which coordinates several homeostatic pathways. The intriguing localisation of mTORC1 to the cellular organelle that plays a crucial role in catabolism enables mTORC1 to feedback to autophagy and lysosomal biogenesis, thus leading mTORC1 to enact precise spatial and temporal control of cell growth. This review will cover the signalling interactions which take place on the surface of lysosomes and the cross-talk which exists between mTORC1 activity and lysosomal function.
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Affiliation(s)
- Yoana Rabanal-Ruiz
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE4 5PL, UK.
| | - Viktor I Korolchuk
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE4 5PL, UK.
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Paquette M, El-Houjeiri L, Pause A. mTOR Pathways in Cancer and Autophagy. Cancers (Basel) 2018; 10:cancers10010018. [PMID: 29329237 PMCID: PMC5789368 DOI: 10.3390/cancers10010018] [Citation(s) in RCA: 199] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 12/22/2017] [Accepted: 01/09/2018] [Indexed: 12/11/2022] Open
Abstract
TOR (target of rapamycin), an evolutionarily-conserved serine/threonine kinase, acts as a central regulator of cell growth, proliferation and survival in response to nutritional status, growth factor, and stress signals. It plays a crucial role in coordinating the balance between cell growth and cell death, depending on cellular conditions and needs. As such, TOR has been identified as a key modulator of autophagy for more than a decade, and several deregulations of this pathway have been implicated in a variety of pathological disorders, including cancer. At the molecular level, autophagy regulates several survival or death signaling pathways that may decide the fate of cancer cells; however, the relationship between autophagy pathways and cancer are still nascent. In this review, we discuss the recent cellular signaling pathways regulated by TOR, their interconnections to autophagy, and the clinical implications of TOR inhibitors in cancer.
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Affiliation(s)
- Mathieu Paquette
- Goodman Cancer Research Center, McGill University, Montréal, QC H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Leeanna El-Houjeiri
- Goodman Cancer Research Center, McGill University, Montréal, QC H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Arnim Pause
- Goodman Cancer Research Center, McGill University, Montréal, QC H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
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43
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mTORC1 as the main gateway to autophagy. Essays Biochem 2017; 61:565-584. [PMID: 29233869 PMCID: PMC5869864 DOI: 10.1042/ebc20170027] [Citation(s) in RCA: 356] [Impact Index Per Article: 50.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 12/16/2022]
Abstract
Cells and organisms must coordinate their metabolic activity with changes in their environment to ensure their growth only when conditions are favourable. In order to maintain cellular homoeostasis, a tight regulation between the synthesis and degradation of cellular components is essential. At the epicentre of the cellular nutrient sensing is the mechanistic target of rapamycin complex 1 (mTORC1) which connects environmental cues, including nutrient and growth factor availability as well as stress, to metabolic processes in order to preserve cellular homoeostasis. Under nutrient-rich conditions mTORC1 promotes cell growth by stimulating biosynthetic pathways, including synthesis of proteins, lipids and nucleotides, and by inhibiting cellular catabolism through repression of the autophagic pathway. Its close signalling interplay with the energy sensor AMP-activated protein kinase (AMPK) dictates whether the cell actively favours anabolic or catabolic processes. Underlining the role of mTORC1 in the coordination of cellular metabolism, its deregulation is linked to numerous human diseases ranging from metabolic disorders to many cancers. Although mTORC1 can be modulated by a number of different inputs, amino acids represent primordial cues that cannot be compensated for by any other stimuli. The understanding of how amino acids signal to mTORC1 has increased considerably in the last years; however this area of research remains a hot topic in biomedical sciences. The current ideas and models proposed to explain the interrelationship between amino acid sensing, mTORC1 signalling and autophagy is the subject of the present review.
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Agergaard J, Bülow J, Jensen JK, Reitelseder S, Bornø A, Drummond MJ, Schjerling P, Holm L. Effect of light-load resistance exercise on postprandial amino acid transporter expression in elderly men. Physiol Rep 2017; 5:5/18/e13444. [PMID: 28963124 PMCID: PMC5617931 DOI: 10.14814/phy2.13444] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 08/04/2017] [Accepted: 08/10/2017] [Indexed: 02/07/2023] Open
Abstract
An impaired amino acid sensing is associated with age‐related loss of skeletal muscle mass. We tested whether light‐load resistance exercise (LL‐RE) affects postprandial amino acid transporter (AAT) expression in aging skeletal muscle. Untrained, healthy men (age: +65 years) were subjected to 13 h of supine rest. After 2 1/2 h of rest, unilateral LL‐RE was conducted (leg extensions, 10 sets of 36 repetitions) at 16% 1RM. Thereafter, the subjects were randomized into groups that orally ingested 40 g of whey protein either as hourly drinks (4 g per drink) (PULSE, N = 10) or two boluses (28 g at 0 h and 12 g at 7 h) (BOLUS, N = 10), or hourly isocaloric maltodextrin drinks (placebo, N = 10). Quadriceps muscle biopsies were taken at 0, 3, 7, and 10 h postexercise from both the resting and exercised leg, from which the membrane protein and mRNA expression of select AATs were analyzed by Western Blot and RT‐PCR, respectively. LAT1 and PAT1 protein expression increased in response to LL‐RE in the PULSE group, and SNAT2 and PAT1 protein expression increased in the BOLUS group when plasma BCAA concentration was low. In all three groups, LL‐RE increased LAT1 mRNA expression, whereas a time course decrease in SNAT2 mRNA expression was observed. LL‐RE increased membrane‐associated AAT protein expression and mRNA expression. Altered AAT protein expression was only seen in groups that ingested whey protein, with the greatest effect observed after hourly feeding. This points toward an importance of AATs in the anabolic response following LL‐RE and protein intake.
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Affiliation(s)
- Jakob Agergaard
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark .,Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Physical Therapy, University of Utah, Salt Lake City, Utah
| | - Jacob Bülow
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.,Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob K Jensen
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.,Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Reitelseder
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.,Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Bornø
- Clinical Metabolomics Core Facility, Rigshospitalet, Copenhagen, Denmark
| | - Micah J Drummond
- Department of Physical Therapy, University of Utah, Salt Lake City, Utah
| | - Peter Schjerling
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.,Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lars Holm
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.,Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Dinkeloo K, Boyd S, Pilot G. Update on amino acid transporter functions and on possible amino acid sensing mechanisms in plants. Semin Cell Dev Biol 2017; 74:105-113. [PMID: 28705659 DOI: 10.1016/j.semcdb.2017.07.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/30/2017] [Accepted: 07/07/2017] [Indexed: 12/25/2022]
Abstract
Amino acids are essential components of plant metabolism, not only as constituents of proteins, but also as precursors of important secondary metabolites and as carriers of organic nitrogen between the organs of the plant. Transport across intracellular membranes and translocation of amino acids within the plant is mediated by membrane amino acid transporters. The past few years have seen the identification of a new family of amino acid transporters in Arabidopsis, the characterization of intracellular amino acid transporters, and the discovery of new roles for already known proteins. While amino acid metabolism needs to be tightly coordinated with amino acid transport activity and carbohydrate metabolism, no gene involved in amino acid sensing in plants has been unequivocally identified to date. This review aims at summarizing the recent data accumulated on the identity and function of amino acid transporters in plants, and discussing the possible identity of amino acid sensors based on data from other organisms.
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Affiliation(s)
- Kasia Dinkeloo
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24060, USA
| | - Shelton Boyd
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24060, USA
| | - Guillaume Pilot
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24060, USA.
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46
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Yao Y, Jones E, Inoki K. Lysosomal Regulation of mTORC1 by Amino Acids in Mammalian Cells. Biomolecules 2017; 7:biom7030051. [PMID: 28686218 PMCID: PMC5618232 DOI: 10.3390/biom7030051] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/03/2017] [Accepted: 07/04/2017] [Indexed: 12/15/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth in eukaryotic cells. The active mTORC1 promotes cellular anabolic processes including protein, pyrimidine, and lipid biosynthesis, and inhibits catabolic processes such as autophagy. Consistent with its growth-promoting functions, hyper-activation of mTORC1 signaling is one of the important pathomechanisms underlying major human health problems including diabetes, neurodegenerative disorders, and cancer. The mTORC1 receives multiple upstream signals such as an abundance of amino acids and growth factors, thus it regulates a wide range of downstream events relevant to cell growth and proliferation control. The regulation of mTORC1 by amino acids is a fast-evolving field with its detailed mechanisms currently being revealed as the precise picture emerges. In this review, we summarize recent progress with respect to biochemical and biological findings in the regulation of mTORC1 signaling on the lysosomal membrane by amino acids.
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Affiliation(s)
- Yao Yao
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
| | - Edith Jones
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 East Catherine Street, Ann Arbor, MI 48109, USA.
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 East Catherine Street, Ann Arbor, MI 48109, USA.
- Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical enter Drive, Ann Arbor, MI 48109, USA.
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47
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The Architecture of the Rag GTPase Signaling Network. Biomolecules 2017; 7:biom7030048. [PMID: 28788436 PMCID: PMC5618229 DOI: 10.3390/biom7030048] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
The evolutionarily conserved target of rapamycin complex 1 (TORC1) couples an array of intra- and extracellular stimuli to cell growth, proliferation and metabolism, and its deregulation is associated with various human pathologies such as immunodeficiency, epilepsy, and cancer. Among the diverse stimuli impinging on TORC1, amino acids represent essential input signals, but how they control TORC1 has long remained a mystery. The recent discovery of the Rag GTPases, which assemble as heterodimeric complexes on vacuolar/lysosomal membranes, as central elements of an amino acid signaling network upstream of TORC1 in yeast, flies, and mammalian cells represented a breakthrough in this field. Here, we review the architecture of the Rag GTPase signaling network with a special focus on structural aspects of the Rag GTPases and their regulators in yeast and highlight both the evolutionary conservation and divergence of the mechanisms that control Rag GTPases.
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48
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Rosario FJ, Powell TL, Jansson T. mTOR folate sensing links folate availability to trophoblast cell function. J Physiol 2017; 595:4189-4206. [PMID: 28374905 DOI: 10.1113/jp272424] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 03/29/2017] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Folate deficiency during pregnancy is associated with restricted fetal growth, although the underlying mechanisms are poorly understood. Here we show that mechanistic target of rapamycin (mTOR) functions as a folate sensor in primary human trophoblast (PHT) cells. Folate sensing by mTOR in PHT cells involves both mTOR Complex 1 and 2 and requires the proton-coupled folate transporter. We report a previously unknown molecular mechanism by which folate regulates trophoblast cell function. Because mTOR is a positive regulator of placental amino acid transport and mitochondrial function, placental mTOR folate sensing may constitute the mechanistic link between maternal folate status and fetal growth. These findings provide new insight into how folate influences human cell physiology and may have implications for our understanding of how altered folate availability causes diseases such as fetal growth restriction, fetal malformations and cancer. ABSTRACT Folate is a water-soluble B vitamin that is essential for cellular methylation reactions and DNA synthesis and repair. Low maternal folate levels in pregnancy are associated with fetal growth restriction, but the underlying mechanisms are poorly understood. Mechanistic target of rapamycin (mTOR) links nutrient availability to cell growth and function by regulating gene expression and protein translation. Here we show that mTOR functions as a folate sensor in primary human trophoblast (PHT) cells. Folate deficiency in PHT cells caused inhibition of mTOR signalling and decreased the activity of key amino acid transporters. Folate sensing by mTOR in PHT cells involves both mTOR Complex 1 and 2 and requires the proton-coupled folate transporter (PCFT, SLC46A1). The involvement of PCFT in mTOR folate sensing is not dependent on its function as a plasma membrane folate transporter. Increasing levels of homocysteine had no effect on PHT mTOR signalling, suggesting that mTOR senses low folate rather than high homocysteine. In addition, we demonstrate that maternal serum folate is positively correlated to placental mTORC1 and mTORC2 signalling activity in human pregnancy. We have identified a previously unknown molecular link between folate availability and cell function involving PCFT and mTOR signalling. We propose that mTOR folate sensing in trophoblast cells matches placental nutrient transport, and therefore fetal growth, to folate availability. These findings may have implications for our understanding of how altered folate availability causes human diseases such as fetal growth restriction, fetal malformations and cancer.
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Affiliation(s)
- Fredrick J Rosario
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Theresa L Powell
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.,Section of Neonatology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Thomas Jansson
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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The lysosome: a crucial hub for AMPK and mTORC1 signalling. Biochem J 2017; 474:1453-1466. [PMID: 28408430 DOI: 10.1042/bcj20160780] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 02/21/2017] [Accepted: 02/27/2017] [Indexed: 12/18/2022]
Abstract
Much attention has recently been focussed on the lysosome as a signalling hub. Following the initial discovery that localisation of the nutrient-sensitive kinase, mammalian target of rapamycin complex 1 (mTORC1), to the lysosome was essential for mTORC1 activation, the field has rapidly expanded to reveal the role of the lysosome as a platform permitting the co-ordination of several homeostatic signalling pathways. Much is now understood about how the lysosome contributes to amino acid sensing by mTORC1, the involvement of the energy-sensing kinase, AMP-activated protein kinase (AMPK), at the lysosome and how both AMPK and mTORC1 signalling pathways feedback to lysosomal biogenesis and regeneration following autophagy. This review will cover the classical role of the lysosome in autophagy, the dynamic signalling interactions which take place on the lysosomal surface and the multiple levels of cross-talk which exist between lysosomes, AMPK and mTORC1.
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50
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Piert M, Shao X, Raffel D, Davenport MS, Montgomery J, Kunju LP, Hockley BG, Siddiqui J, Scott PJH, Chinnaiyan AM, Rajendiran T. Preclinical Evaluation of 11C-Sarcosine as a Substrate of Proton-Coupled Amino Acid Transporters and First Human Application in Prostate Cancer. J Nucl Med 2017; 58:1216-1223. [PMID: 28302759 DOI: 10.2967/jnumed.116.173179] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/14/2017] [Indexed: 12/14/2022] Open
Abstract
Sarcosine is a known substrate of proton-coupled amino acid transporters (PATs), which are overexpressed in selected tissues and solid tumors. Sarcosine, an N-methyl derivative of the amino acid glycine and a metabolic product of choline, plays an important role for prostate cancer aggressiveness and progression. Methods:11C-radiolabeled sarcosine was tested as a new PET imaging probe in comparison with 11C-choline in 2 prostate cancer tumor xenograft models (DU-145 and PC-3). We characterized 11C-sarcosine transport in PC-3 and LNCaP tumor cells and performed 11C-sarcosine PET with CT in the first human subject with localized Gleason 4 + 3 prostate cancer. Target metabolite analyses of sarcosine and its natural precursors, glycine and choline, were performed from independent human prostate tissues. Results: In vitro assays indicated blockage of 11C-sarcosine uptake into PC-3 and LNCaP tumor cells by excess unlabeled (cold) sarcosine. 5-hydroxy-l-tryptophan, but not 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid, competitively inhibited 11C-sarcosine tumor cell uptake, confirming PAT-mediated transport. In vivo tumor-to-background ratios (TBRs) obtained from 11C-sarcosine PET were significantly elevated compared with 11C-choline in DU-145 (TBR: 1.92 ± 0.11 for 11C-sarcosine vs. 1.41 ± 0.13 for 11C-choline [n = 10; P < 0.002]) and PC-3 tumors (TBR: 1.89 ± 0.2 for 11C-sarcosine vs. 1.34 ± 0.16 for 11C-choline [n = 7; P < 0.002]). 11C-sarcosine produced high-contrast images in 1 case of localized clinically significant prostate cancer. Target metabolite analyses revealed significant stepwise increases of sarcosine, glycine, and choline tissue levels from benign prostate tissue to localized prostate cancer and subsequently metastatic disease. 11C-sarcosine showed a favorable radiation dosimetry with an effective dose estimate of 0.0045 mSv/MBq, resulting in 2.68 mSv for a human subject (600-MBq dose). Conclusion:11C-sarcosine is a novel radiotracer for PATs and shows initial utility for prostate cancer imaging, with potential benefit over commonly used 11C-choline.
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Affiliation(s)
- Morand Piert
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - Xia Shao
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - David Raffel
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | | | | | | | - Brian G Hockley
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - Javed Siddiqui
- Pathology Department, University of Michigan, Ann Arbor, Michigan; and.,Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, Michigan
| | - Peter J H Scott
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - Arul M Chinnaiyan
- Pathology Department, University of Michigan, Ann Arbor, Michigan; and.,Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, Michigan
| | - Thekkelnaycke Rajendiran
- Pathology Department, University of Michigan, Ann Arbor, Michigan; and.,Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, Michigan
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