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Boss-Kennedy A, Kim D, Barai P, Maldonado C, Reyes-Ordoñez A, Chen J. Muscle cell-derived Ccl8 is a negative regulator of skeletal muscle regeneration. FASEB J 2024; 38:e23841. [PMID: 39051762 PMCID: PMC11279459 DOI: 10.1096/fj.202400184r] [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: 01/23/2024] [Revised: 06/24/2024] [Accepted: 07/12/2024] [Indexed: 07/27/2024]
Abstract
Skeletal muscles undergo robust regeneration upon injury, and infiltrating immune cells play a major role in not only clearing damaged tissues but also regulating the myogenic process through secreted cytokines. Chemokine C-C motif ligand 8 (Ccl8), along with Ccl2 and Ccl7, has been reported to mediate inflammatory responses to suppress muscle regeneration. Ccl8 is also expressed by muscle cells, but a role of the muscle cell-derived Ccl8 in myogenesis has not been reported. In this study, we found that knockdown of Ccl8, but not Ccl2 or Ccl7, led to increased differentiation of C2C12 myoblasts. Analysis of existing single-cell transcriptomic datasets revealed that both immune cells and muscle stem cells (MuSCs) in regenerating muscles express Ccl8, with the expression by MuSCs at a much lower level, and that the temporal patterns of Ccl8 expression were different in MuSCs and macrophages. To probe a function of muscle cell-derived Ccl8 in vivo, we utilized a mouse system in which Cas9 was expressed in Pax7+ myogenic progenitor cells (MPCs) and Ccl8 gene editing was induced by AAV9-delivered sgRNA. Depletion of Ccl8 in Pax7+ MPCs resulted in accelerated muscle regeneration after barium chloride-induced injury in both young and middle-aged mice, and intramuscular administration of a recombinant Ccl8 reversed the phenotype. Accelerated regeneration was also observed when Ccl8 was depleted in Myf5+ or MyoD+ MPCs by similar approaches. Our results suggest that muscle cell-derived Ccl8 plays a unique role in regulating the initiation of myogenic differentiation during injury-induced muscle regeneration.
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Affiliation(s)
- A Boss-Kennedy
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - D Kim
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - P Barai
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - C Maldonado
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - A Reyes-Ordoñez
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - J Chen
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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2
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Cho YH, Seo TB. Effect of concurrent aerobic exercise and bone marrow stromal cell transplantation on time-dependent changes of myogenic differentiation-related cascades in soleus muscle after sciatic nerve injury. J Exerc Rehabil 2023; 19:11-18. [PMID: 36910676 PMCID: PMC9993002 DOI: 10.12965/jer.2346004.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/09/2023] [Indexed: 02/25/2023] Open
Abstract
The purpose of this study was to investigate the time-dependent alteration in whether concurrent aerobic exercise and bone marrow stromal cell (BMSC) engraftment could regulate myogenic differentiation-related signaling pathway in the soleus up to 35 days after sciatic nerve injury (SNI). The rats were divided as follows: the normal control (CON, n=5), sedentary group (SED, n=20), treadmill exercise group (TEX, n=20), BMSC transplantation group (BMSC, n=20), TEX+BMSC transplantation group (TEX+BMSC, n=20) 7, 14, 21, and 35 days after SNI. SNI was applied into the thigh and treadmill exercise was comprised of walking at a speed of 4 to 8 m/min for 30 min once a day. Harvested BMSC at a density of 5×106 in 50-μL phosphate-buff-ered saline was injected into the injury site. Phosphorylated (p) extracellular signal-regulated kinase 1/2 expression was dramatically upregulated in BMSC and BMSC+EX groups from 21 days after SNI compared to those in the SED group. P-ribosomal s6 kinase (RSK) was sharply increased 14 days later, and then rapidly downregulated from day 21, whereas TEX, BMSC and TEX+ BMSC groups significantly kept up expression levels of p-RSK until 35 days post injury than SED group. TEX+BMSC group significantly increased activation of protein kinase B-mammalian target of rapamycin in the soleus from day 14 and myoblast determination protein 1-myogen-in pathways was activated in TEX+BMSC group from day 21. Present findings provide information that combined intervention of aerobic exercise and BMSC transplantation might be a reliable therapeutic strategy for overcoming the morphological and functional problems in denervated soleus muscle.
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Affiliation(s)
- Yeong-Hyun Cho
- Department of Kinesiology, College of Natural Science, Jeju National University, Jeju, Korea
| | - Tae-Beom Seo
- Department of Kinesiology, College of Natural Science, Jeju National University, Jeju, Korea
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Kwak MK, Ha ES, Lee J, Choi YM, Kim BJ, Hong EG. C-C motif chemokine ligand 2 promotes myogenesis of myoblasts via the AKT-mTOR pathway. Aging (Albany NY) 2022; 14:9860-9876. [PMID: 36575043 PMCID: PMC9831732 DOI: 10.18632/aging.204451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 11/30/2022] [Indexed: 12/28/2022]
Abstract
Muscle mass decreases with aging, while the C-C motif chemokine ligand 2 (CCL2) increases with aging; in this context, CCL2 can be considered a potential aging-promoting factor. Thus, CCL2 knockout mice are expected to exhibit anti-aging effects including protection against loss of muscle mass. However, instead, muscle amount and recovery of damaged muscles are decreased in CCL2 knockout mice. Therefore, we hypothesized that increasing CCL2 in the elderly might be related to compensation for loss of muscle mass. To confirm the relationship between muscle and CCL2, we sought to establish the role of CCL2 in C2C12 cells and Human Skeletal Muscle Myoblast (HSMM) cells. The myotube (MT) fusion index increased with CCL2 compared to 5day CCL2 vehicle only (27.0 % increase, P<0.05) in immunocytochemistry staining (ICC) data. CCL2 also restored MTs atrophy caused by dexamethasone (21.8 % increase, P<0.0001). p-mTOR/mTOR and p-AKT/total AKT increased with CCL2 compared to CCL2 vehicle only (18.3 and 30.5% increase respectively, P<0.05) and decreased with CCR2-siRNA compared to CCL2 (38.9 % (P<0.05) and 56.7% (P<0.005) reduction respectively). In conclusion, CCL2 positively affects myogenesis by CCR2 via AKT-mTOR signaling pathways. CCL2 might have potential as a therapeutic target for low muscle mass and muscle recovery.
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Affiliation(s)
- Mi Kyung Kwak
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong-Si, Gyeonggi-Do 18450, Korea
| | - Eun Suk Ha
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong-Si, Gyeonggi-Do 18450, Korea
| | - Jiwoo Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong-Si, Gyeonggi-Do 18450, Korea
| | - Yun Mi Choi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong-Si, Gyeonggi-Do 18450, Korea
| | - Beom-Jun Kim
- Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, Songpa-Gu, Seoul 05505, Korea
| | - Eun-Gyoung Hong
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong-Si, Gyeonggi-Do 18450, Korea
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4
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Baek M, Cho H, Min DS, Choi CS, Yoon M. Self-transducible LRS-UNE-L peptide enhances muscle regeneration. J Cachexia Sarcopenia Muscle 2022; 13:1277-1288. [PMID: 35178893 PMCID: PMC8977975 DOI: 10.1002/jcsm.12947] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 12/13/2021] [Accepted: 01/17/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Muscle regeneration includes proliferation and differentiation of muscle satellite cells, which involves the mammalian target of rapamycin (mTOR). We identified the C-terminal unique attached sequence motif (UNE) domain of leucyl-tRNA synthetase (LRS-UNE-L) as an mTORC1 (mTOR complex1)-activating domain that acts through Vps34 and phospholipase D1 (PLD1) when introduced in the form of a muscle-enhancing peptide. METHODS In vitro Vps34 lipid kinase assay, phosphatidylinositol 3-phosphate (PI(3)P) measurement, in vivo PLD1 assay, and western blot assay were performed in HEK293 cells to test the effect of the LRS-UNE-L on the Vps34-PLD1-mTOR pathway. Adeno-associated virus (AAV)-LRS-UNE-L was transduced in C2C12 cells in vitro, in BaCl2 -injured tibialis anterior (TA) muscles, and in 18-month-old TA muscles to analyse its effect on myogenesis, muscle regeneration, and aged muscle, respectively. The muscle-specific cell-permeable peptide M12 was fused with LRS-UNE-L and tested for cell integration in C2C12 and HEK293 cells using FACS analysis and immunocytochemistry. Finally, M12-LRS-UNE-L was introduced into BaCl2 -injured TA muscles of 15-week-old Pld1+/+ or Pld1-/- mice, and its effect was analysed by measurement of cross-sectional area of regenerating muscle fibres. RESULTS The LRS-UNE-L expression restored amino acid-induced S6K1 phosphorylation in LRS knockdown cells in a RagD GTPases-independent manner (421%, P = 0.007 vs. LRS knockdown control cells). The LRS-UNE-L domain was directly bound to Vps34; this interaction was accompanied by increases in Vps34 activity (166%, P = 0.0352), PI(3)P levels (146%, P = 0.0039), and PLD1 activity (228%, P = 0.0294) compared with amino acid-treated control cells, but it did not affect autophagic flux. AAV-delivered LRS-UNE-L domain augmented S6K1 phosphorylation (174%, P = 0.0013), mRNA levels of myosin heavy chain (MHC) (122%, P = 0.0282) and insulin-like growth factor 2 (IGF2) (146%, P = 0.008), and myogenic fusion (133%, P = 0.0479) in C2C12 myotubes. AAV-LRS-UNE-L increased the size of regenerating muscle fibres in BaCl2 -injured TA muscles (124%, P = 0.0279) (n = 9-10), but it did not change the muscle fibre size of TA muscles in old mice. M12-LRS-UNE-L was preferentially delivered into C2C12 cells compared with HEK293 cells and augmented regeneration of BaCl2 -injured TA muscles in a PLD1-dependent manner (116%, P = 0.0022) (n = 6). CONCLUSIONS Our results provide compelling evidence that M12-LRS-UNE-L could be a muscle-enhancing protein targeting mTOR.
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Affiliation(s)
- Mi‐Ock Baek
- Department of Health Sciences and TechnologyGAIHST, Gachon UniversityIncheonRepublic of Korea
| | - Hye‐Jeong Cho
- Lee Gil Ya Cancer and Diabetes InstituteIncheonRepublic of Korea
| | - Do Sik Min
- College of PharmacyYonsei UniversityIncheonRepublic of Korea
| | - Cheol Soo Choi
- Korea Mouse Metabolic Phenotyping CenterLee Gil Ya Cancer and Diabetes Institute, Gachon UniversityIncheonRepublic of Korea
- Department of Internal Medicine, Gil Medical CenterGachon UniversityIncheonRepublic of Korea
- Department of Molecular MedicineGachon University College of MedicineIncheonRepublic of Korea
| | - Mee‐Sup Yoon
- Department of Health Sciences and TechnologyGAIHST, Gachon UniversityIncheonRepublic of Korea
- Lee Gil Ya Cancer and Diabetes InstituteIncheonRepublic of Korea
- Department of Molecular MedicineGachon University College of MedicineIncheonRepublic of Korea
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5
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Dai C, Reyes-Ordoñez A, You JS, Chen J. A non-translational role of threonyl-tRNA synthetase in regulating JNK signaling during myogenic differentiation. FASEB J 2021; 35:e21948. [PMID: 34569098 DOI: 10.1096/fj.202101094r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/30/2021] [Accepted: 09/08/2021] [Indexed: 11/11/2022]
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are house-keeping enzymes that are essential for protein synthesis. However, it has become increasingly evident that some aaRSs also have non-translational functions. Here we report the identification of a non-translational function of threonyl-tRNA synthetase (ThrRS) in myogenic differentiation. We find that ThrRS negatively regulates myoblast differentiation in vitro and injury-induced skeletal muscle regeneration in vivo. This function is independent of amino acid binding or aminoacylation activity of ThrRS, and knockdown of ThrRS leads to enhanced differentiation without affecting the global protein synthesis rate. Furthermore, we show that the non-catalytic new domains (UNE-T and TGS) of ThrRS are both necessary and sufficient for the myogenic function. In searching for a molecular mechanism of this new function, we find the kinase JNK to be a downstream target of ThrRS. Our data further reveal MEKK4 and MKK4 as upstream regulators of JNK in myogenesis and the MEKK4-MKK4-JNK pathway to be a mediator of the myogenic function of ThrRS. Finally, we show that ThrRS physically interacts with Axin1, disrupts Axin1-MEKK4 interaction and consequently inhibits JNK signaling. In conclusion, we uncover a non-translational function for ThrRS in the maintenance of homeostasis of skeletal myogenesis and identify the Axin1-MEKK4-MKK4-JNK signaling axis to be an immediate target of ThrRS action.
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Affiliation(s)
- Chong Dai
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Adriana Reyes-Ordoñez
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jae-Sung You
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jie Chen
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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6
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Ahn J, Kim MJ, Yoo A, Ahn J, Ha TY, Jung CH, Seo HD, Jang YJ. Identifying Codium fragile extract components and their effects on muscle weight and exercise endurance. Food Chem 2021; 353:129463. [PMID: 33743428 DOI: 10.1016/j.foodchem.2021.129463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 02/04/2021] [Accepted: 02/22/2021] [Indexed: 01/29/2023]
Abstract
Codium fragile (CF) is a type of green algae consumed as kimchi in Asia. UPLC-QTOF-MS/MS analysis showed that CF contain lysophosphatidyl choline, canthaxanthin, retinoic acid, α-tocopherol, and unsaturated fatty acids, which reportedly improve skeletal muscle health. However, the effect of CF on skeletal muscle mass and function remains to be elucidated. In mice fed with CF extracts, exercise endurance and muscle weight increased. CF extracts enhanced protein synthesis and myogenic differentiation through the mTORC1 pathway. CF extracts also promoted oxidative muscle fiber formation and mitochondrial biogenesis through the PGC-1α-related signaling pathway. Upregulation of PGC-1α by CF extracts was abolished by EX527 SIRT1 inhibitor treatment. Changed signaling molecules in the CF extracts were partially regulated by canthaxanthin, a new compound in CF extracts, suggesting that canthaxanthin contribute synergistically to the effect of CF extracts. Therefore, CF is a potential food source for sport nutrition or prevention of sarcopenia.
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Affiliation(s)
- Jisong Ahn
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea; Department of Food Science and Technology, Chonbuk National University, Jeonju-si 54896, Republic of Korea
| | - Min Jung Kim
- Healthcare Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea
| | - Ahyoung Yoo
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea; Department of Food and Nutrition, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Jiyun Ahn
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea; Division of Food Biotechnology, University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Tae Youl Ha
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea; Division of Food Biotechnology, University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Chang Hwa Jung
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea; Division of Food Biotechnology, University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Hyo Deok Seo
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea
| | - Young Jin Jang
- Natural Materials and Metabolism Research Group, Korea Food Research Institute, Wanju-gun 55365, Republic of Korea; Major of Food Science & Technology, Seoul Women's University, Seoul 01797, Republic of Korea.
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7
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Huot JR, Thompson B, McMullen C, Marino JS, Arthur ST. GSI Treatment Preserves Protein Synthesis in C2C12 Myotubes. Cells 2021; 10:cells10071786. [PMID: 34359954 PMCID: PMC8307118 DOI: 10.3390/cells10071786] [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: 05/27/2021] [Revised: 07/08/2021] [Accepted: 07/13/2021] [Indexed: 11/25/2022] Open
Abstract
It has been demonstrated that inhibiting Notch signaling through γ-secretase inhibitor (GSI) treatment increases myogenesis, AKT/mTOR signaling, and muscle protein synthesis (MPS) in C2C12 myotubes. The purpose of this study was to determine if GSI-mediated effects on myogenesis and MPS are dependent on AKT/mTOR signaling. C2C12 cells were assessed for indices of myotube formation, anabolic signaling, and MPS following GSI treatment in combination with rapamycin and API-1, inhibitors of mTOR and AKT, respectively. GSI treatment increased several indices of myotube fusion and MPS in C2C12 myotubes. GSI-mediated effects on myotube formation and fusion were completely negated by treatment with rapamycin and API-1. Meanwhile, GSI treatment was able to rescue MPS in C2C12 myotubes exposed to rapamycin or rapamycin combined with API-1. Examination of protein expression revealed that GSI treatment was able to rescue pGSK3β Ser9 despite AKT inhibition by API-1. These findings demonstrate that GSI treatment is able to rescue MPS independent of AKT/mTOR signaling, possibly via GSK3β modulation.
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Affiliation(s)
- Joshua R. Huot
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA; (J.R.H.); (B.T.); (C.M.); (J.S.M.)
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Brian Thompson
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA; (J.R.H.); (B.T.); (C.M.); (J.S.M.)
| | - Charlotte McMullen
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA; (J.R.H.); (B.T.); (C.M.); (J.S.M.)
| | - Joseph S. Marino
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA; (J.R.H.); (B.T.); (C.M.); (J.S.M.)
| | - Susan T. Arthur
- Laboratory of Systems Physiology, Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA; (J.R.H.); (B.T.); (C.M.); (J.S.M.)
- Correspondence: ; Tel.: +1-(704)-687-0856
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Oh M, Kim SY, Park S, Kim KN, Kim SH. Phytochemicals in Chinese Chive ( Allium tuberosum) Induce the Skeletal Muscle Cell Proliferation via PI3K/Akt/mTOR and Smad Pathways in C2C12 Cells. Int J Mol Sci 2021; 22:2296. [PMID: 33669060 PMCID: PMC7956299 DOI: 10.3390/ijms22052296] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 01/10/2023] Open
Abstract
Chinese chive (Allium tuberosum) is a medicinal food that is cultivated and consumed mainly in Asian countries. Its various phytochemicals and physiological effects have been reported, but only a few phytochemicals are available for skeletal muscle cell proliferation. Herein, we isolated a new compound, kaempferol-3-O-(6″-feruloyl)-sophoroside (1), along with one known flavonoid glycoside (2) and six amino acid (3-8) compounds from the water-soluble fraction of the shoot of the Chinese chive. The isolated compounds were identified using extensive spectroscopic methods, including 1D and 2D NMR, and evaluated for their proliferation activity on skeletal muscle cells. Among the tested compounds, newly isolated flavonoid (1) and 5-aminouridine (7) up-regulated PI3K/Akt/mTOR pathways, which implies a positive effect on skeletal muscle growth and differentiation. In particular, compound 1 down-regulated the Smad pathways, which are negative regulators of skeletal muscle growth. Collectively, we suggest that major constituents of Chinese chive, flavonoids and amino acids, might be used in dietary supplements that aid skeletal muscle growth.
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Affiliation(s)
- Mira Oh
- College of pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea;
| | - Seo-Young Kim
- Chuncheon Center, Korea Basic Science Institute (KBSI), Chuncheon 24341, Korea; (S.-Y.K.); (S.P.)
| | - SeonJu Park
- Chuncheon Center, Korea Basic Science Institute (KBSI), Chuncheon 24341, Korea; (S.-Y.K.); (S.P.)
| | - Kil-Nam Kim
- Chuncheon Center, Korea Basic Science Institute (KBSI), Chuncheon 24341, Korea; (S.-Y.K.); (S.P.)
| | - Seung Hyun Kim
- College of pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea;
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Phosphatidic Acid Stimulates Myoblast Proliferation through Interaction with LPA1 and LPA2 Receptors. Int J Mol Sci 2021; 22:ijms22031452. [PMID: 33535610 PMCID: PMC7867176 DOI: 10.3390/ijms22031452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 01/19/2021] [Indexed: 12/31/2022] Open
Abstract
Phosphatidic acid (PA) is a bioactive phospholipid capable of regulating key biological functions, including neutrophil respiratory burst, chemotaxis, or cell growth and differentiation. However, the mechanisms whereby PA exerts these actions are not completely understood. In this work, we show that PA stimulates myoblast proliferation, as determined by measuring the incorporation of [3H]thymidine into DNA and by staining the cells with crystal violet. PA induced the rapid phosphorylation of Akt and ERK1/2, and pretreatment of the cells with specific small interferin RNA (siRNA) to silence the genes encoding these kinases, or with selective pharmacologic inhibitors, blocked PA-stimulated myoblast proliferation. The mitogenic effects of PA were abolished by the preincubation of the myoblasts with pertussis toxin, a Gi protein inhibitor, suggesting the implication of Gi protein-coupled receptors in this action. Although some of the effects of PA have been associated with its possible conversion to lysoPA (LPA), treatment of the myoblasts with PA for up to 60 min did not produce any significant amount of LPA in these cells. Of interest, pharmacological blockade of the LPA receptors 1 and 2, or specific siRNA to silence the genes encoding these receptors, abolished PA-stimulated myoblast proliferation. Moreover, PA was able to compete with LPA for binding to LPA receptors, suggesting that PA can act as a ligand of LPA receptors. It can be concluded that PA stimulates myoblast proliferation through interaction with LPA1 and LPA2 receptors and the subsequent activation of the PI3K/Akt and MEK/ERK1-2 pathways, independently of LPA formation.
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10
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Chang EI, Hetrick B, Wesolowski SR, McCurdy CE, Rozance PJ, Brown LD. A Two-Week Insulin Infusion in Intrauterine Growth Restricted Fetal Sheep at 75% Gestation Increases Skeletal Myoblast Replication but Did Not Restore Muscle Mass or Increase Fiber Number. Front Endocrinol (Lausanne) 2021; 12:785242. [PMID: 34917036 PMCID: PMC8670988 DOI: 10.3389/fendo.2021.785242] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/02/2021] [Indexed: 01/14/2023] Open
Abstract
Intrauterine growth restricted (IUGR) fetuses are born with lower skeletal muscle mass, fewer proliferating myoblasts, and fewer myofibers compared to normally growing fetuses. Plasma concentrations of insulin, a myogenic growth factor, are lower in IUGR fetuses. We hypothesized that a two-week insulin infusion at 75% gestation would increase myoblast proliferation and fiber number in IUGR fetal sheep. Catheterized control fetuses received saline (CON-S, n=6), and the IUGR fetuses received either saline (IUGR-S, n=7) or insulin (IUGR-I, 0.014 ± 0.001 units/kg/hr, n=11) for 14 days. Fetal arterial blood gases and plasma amino acid levels were measured. Fetal skeletal muscles (biceps femoris, BF; and flexor digitorum superficialis, FDS) and pancreases were collected at necropsy (126 ± 2 dGA) for immunochemistry analysis, real-time qPCR, or flow cytometry. Insulin concentrations in IUGR-I and IUGR-S were lower vs. CON-S (P ≤ 0.05, group). Fetal arterial PaO2, O2 content, and glucose concentrations were lower in IUGR-I vs. CON-S (P ≤ 0.01) throughout the infusion period. IGF-1 concentrations tended to be higher in IUGR-I vs. IUGR-S (P=0.06), but both were lower vs. CON-S (P ≤ 0.0001, group). More myoblasts were in S/G2 cell cycle stage in IUGR-I vs. both IUGR-S and CON-S (145% and 113%, respectively, P ≤ 0.01). IUGR-I FDS muscle weighed 40% less and had 40% lower fiber number vs. CON-S (P ≤ 0.05) but were not different from IUGR-S. Myonuclear number per fiber and the mRNA expression levels of muscle regulatory factors were not different between groups. While the pancreatic β-cell mass was lower in both IUGR-I and IUGR-S compared to CON-S, the IUGR groups were not different from each other indicating that feedback inhibition by endogenous insulin did not reduce β-cell mass. A two-week insulin infusion at 75% gestation promoted myoblast proliferation in the IUGR fetus but did not increase fiber or myonuclear number. Myoblasts in the IUGR fetus retain the capacity to proliferate in response to mitogenic stimuli, but intrinsic defects in the fetal myoblast by 75% gestation may limit the capacity to restore fiber number.
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MESH Headings
- Animals
- Drug Administration Schedule
- Female
- Fetal Development/drug effects
- Fetal Development/physiology
- Fetal Growth Retardation/drug therapy
- Fetal Growth Retardation/pathology
- Hypoglycemic Agents/administration & dosage
- Infusions, Intravenous
- Insulin/administration & dosage
- Muscle Development/drug effects
- Muscle Development/physiology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/pathology
- Muscle Fibers, Skeletal/physiology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiology
- Myoblasts, Skeletal/drug effects
- Myoblasts, Skeletal/pathology
- Myoblasts, Skeletal/physiology
- Pregnancy
- Sheep
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Affiliation(s)
- Eileen I. Chang
- Perinatal Research Center, Department of Pediatrics, Section of Neonatology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Byron Hetrick
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Stephanie R. Wesolowski
- Perinatal Research Center, Department of Pediatrics, Section of Neonatology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Carrie E. McCurdy
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Paul J. Rozance
- Perinatal Research Center, Department of Pediatrics, Section of Neonatology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Laura D. Brown
- Perinatal Research Center, Department of Pediatrics, Section of Neonatology, University of Colorado School of Medicine, Aurora, CO, United States
- *Correspondence: Laura D. Brown,
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11
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Zhang L, Duan Y, Guo Q, Wang W, Li F. A selectively suppressing amino acid transporter: Sodium-coupled neutral amino acid transporter 2 inhibits cell growth and mammalian target of rapamycin complex 1 pathway in skeletal muscle cells. ACTA ACUST UNITED AC 2020; 6:513-520. [PMID: 33364468 PMCID: PMC7750797 DOI: 10.1016/j.aninu.2020.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/11/2020] [Accepted: 03/13/2020] [Indexed: 12/18/2022]
Abstract
Sodium-coupled neutral amino acid transporter 2 (SNAT2), also known as solute carrier family 38 member 2 (SLC38A2), is expressed in the skeletal muscle. Our research previously indicated that SNAT2 mRNA expression level in the skeletal muscle was modulated by genotype and dietary protein. The aim of this study was to investigate the key role of the amino acid transporter SNAT2 in muscle cell growth, differentiation, and related signaling pathways via SNAT2 suppression using the inhibitor α-methylaminoisobutyric acid (MeAIB). The results showed that SNAT2 suppression down-regulated both the mRNA and protein expression levels of SNAT2 in C2C12 cells, inhibited cell viability and differentiation of the cell, and regulated the cell distribution in G0/G1 and S phases (P < 0.05). Meanwhile, most of the intercellular amino acid content of the cells after MeAIB co-culturing was significantly lower (P < 0.05). Furthermore, the mRNA expression levels of system L amino acid transporter 1 (LAT1), silent information regulator 1, and peroxisome proliferator-activated receptor-gamma co-activator 1 alpha, as well as the protein expression levels of amino acid transporters LAT1 and vacuolar protein sorting 34, were all down-regulated. The phosphorylated protein expression levels of mammalian target of rapamycin (mTOR), regulatory-associated protein of mTOR, 4E binding protein 1, and ribosomal protein S6 kinase 1 after MeAIB treatment were also significantly down-regulated (P < 0.05), which could contribute to the importance of SNAT2 in amino acid transportation and skeletal muscle cell sensing. In conclusion, SNAT2 suppression inhibited C2C12 cell growth and differentiation, as well as the availability of free amino acids. Although the mTOR complex 1 signaling pathway was found to be involved, its response to different nutrients requires further study.
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Affiliation(s)
- Lingyu Zhang
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan 410125, China.,University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Yehui Duan
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan 410125, China
| | - Qiuping Guo
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan 410125, China.,University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Wenlong Wang
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan 410125, China.,Laboratory of Animal Nutrition and Human Health, School of Biology, Hunan Normal University, Changsha, 410018, China
| | - Fengna Li
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China.,Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan 410125, China
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12
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Rudar M, Columbus DA, Steinhoff-Wagner J, Suryawan A, Nguyen HV, Fleischmann R, Davis TA, Fiorotto ML. Leucine Supplementation Does Not Restore Diminished Skeletal Muscle Satellite Cell Abundance and Myonuclear Accretion When Protein Intake Is Limiting in Neonatal Pigs. J Nutr 2020; 150:22-30. [PMID: 31518419 PMCID: PMC6946895 DOI: 10.1093/jn/nxz216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/10/2019] [Accepted: 08/08/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Rapid growth of skeletal muscle in the neonate requires the coordination of protein deposition and myonuclear accretion. During this developmental stage, muscle protein synthesis is highly sensitive to amino acid supply, especially Leu, but we do not know if this is true for satellite cells, the source of muscle fiber myonuclei. OBJECTIVE We examined whether dietary protein restriction reduces myonuclear accretion in the neonatal pig, and if any reduction in myonuclear accretion is mitigated by restoring Leu intake. METHODS Neonatal pigs (1.53 ± 0.2 kg) were fitted with jugular vein and gastric catheters and fed 1 of 3 isoenergetic milk replacers every 4 h for 21 d: high protein [HP; 22.5 g protein/(kg/d); n= 8]; restricted protein [RP; 11.2 g protein/(kg/d); n= 10]; or restricted protein with Leu [RPL; 12.0 g protein/(kg/d); n= 10]. Pigs were administered 5-bromo-2'-deoxyuridine (BrdU; 15 mg/kg) intravenously every 12 h from days 6 to 8. Blood was sampled on days 6 and 21 to measure plasma Leu concentrations. On day 21, pigs were killed and the longissimus dorsi (LD) muscle was collected to measure cell morphometry, satellite cell abundance, myonuclear accretion, and insulin-like growth factor (IGF) system expression. RESULTS Compared with HP pigs, postprandial plasma Leu concentration in RP pigs was 37% and 47% lower on days 6 and 21, respectively (P < 0.05); Leu supplementation in RPL pigs restored postprandial Leu to HP concentrations. Dietary protein restriction reduced LD myofiber cross-sectional area by 21%, satellite cell abundance by 35%, and BrdU+ myonuclear abundance by 25% (P < 0.05); Leu did not reverse these outcomes. Dietary protein restriction reduced LD muscle IGF2 expression by 60%, but not IGF1 or IGF1R expression (P < 0.05); Leu did not rescue IGF2 expression. CONCLUSIONS Satellite cell abundance and myonuclear accretion in neonatal pigs are compromised when dietary protein intake is restricted and are not restored with Leu supplementation.
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Affiliation(s)
- Marko Rudar
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Daniel A Columbus
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Julia Steinhoff-Wagner
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Agus Suryawan
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Hanh V Nguyen
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Ryan Fleischmann
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Teresa A Davis
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Marta L Fiorotto
- USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA,Address correspondence to MLF (E-mail: )
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13
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Dhanani ZN, Mann G, Adegoke OAJ. Depletion of branched-chain aminotransferase 2 (BCAT2) enzyme impairs myoblast survival and myotube formation. Physiol Rep 2019; 7:e14299. [PMID: 31833233 PMCID: PMC6908738 DOI: 10.14814/phy2.14299] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 12/15/2022] Open
Abstract
Much is known about the positive effects of branched-chain amino acids (BCAA) in regulating muscle protein metabolism. Comparatively much less is known about the effects of these amino acids and their metabolites in regulating myotube formation. Using cultured myoblasts, we showed that although leucine is required for myotube formation, this requirement is easily met by α-ketoisocaproic acid, the ketoacid of leucine. We then demonstrated increases in the expression of the first two enzymes in the catabolism of the three BCAA, branched-chain amino transferase (BCAT2) and branched-chain α-ketoacid dehydrogenase (BCKD), with ~3× increase in BCKD protein expression (p < .05) during differentiation. Furthermore, depletion of BCAT2 abolished myoblast differentiation, as indicated by reduction in the levels of myosin heavy chain-1, troponin and myogenin. Supplementation of incubation medium with branched-chain α-ketoacids or related metabolites derivable from BCAT2 functions did not rescue the defects. However, co-depletion of BCKD kinase partially rescued the defects. Collectively, our data indicate a requirement for BCAA catabolism during myotube formation and that this requirement for BCAT2 likely goes beyond the need for this enzyme to generate the α-ketoacids of the BCAA.
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Affiliation(s)
- Zameer N. Dhanani
- School of Kinesiology and Health ScienceMuscle Health Research CentreYork UniversityTorontoONCanada
| | - Gagandeep Mann
- School of Kinesiology and Health ScienceMuscle Health Research CentreYork UniversityTorontoONCanada
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14
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Caldow MK, Ham DJ, Trieu J, Chung JD, Lynch GS, Koopman R. Glycine Protects Muscle Cells From Wasting in vitro via mTORC1 Signaling. Front Nutr 2019; 6:172. [PMID: 31803749 PMCID: PMC6871541 DOI: 10.3389/fnut.2019.00172] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/25/2019] [Indexed: 12/25/2022] Open
Abstract
Glycine supplementation can protect skeletal muscles of mice from cancer-induced wasting, but the mechanisms underlying this protection are not well-understood. The aim of this study was to determine whether exogenous glycine directly protects skeletal muscle cells from wasting. C2C12 muscle cells were exposed to non-inflammatory catabolic stimuli via two models: serum withdrawal (SF) for 48 h; or incubation in HEPES buffered saline (HBS) for up to 5 h. Cells were supplemented with glycine or equimolar concentrations of L-alanine. SF- and HBS-treated myotubes (with or without L-alanine) were ~20% and ~30% smaller than control myotubes. Glycine-treated myotubes were up to 20% larger (P < 0.01) compared to cells treated with L-alanine in both models of muscle cell atrophy. The mTORC1 inhibitor rapamycin prevented the glycine-stimulated protection of myotube diameter, and glycine-stimulated S6 phosphorylation, suggesting that mTORC1 signaling may be necessary for glycine's protective effects in vitro. Increasing glycine availability may be beneficial for muscle wasting conditions associated with inadequate nutrient intake.
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Affiliation(s)
- Marissa K Caldow
- Centre for Muscle Research, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Daniel J Ham
- Centre for Muscle Research, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Jennifer Trieu
- Centre for Muscle Research, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Jin Dylan Chung
- Centre for Muscle Research, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Gordon S Lynch
- Centre for Muscle Research, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - René Koopman
- Centre for Muscle Research, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
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15
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UCHL1 regulates muscle fibers and mTORC1 activity in skeletal muscle. Life Sci 2019; 233:116699. [PMID: 31356902 DOI: 10.1016/j.lfs.2019.116699] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 01/25/2023]
Abstract
AIMS Skeletal muscle wasting is associated with many chronic diseases. Effective prevention and treatment of muscle wasting remain as a challenging task due to incomplete understanding of mechanisms by which muscle mass is maintained and regulated. This study investigated the functional role of Ubiquitin C-terminal hydrolase L1 (UCHL1) in skeletal muscle. MAIN METHODS Mice with skeletal muscle specific gene knockout of UCHL1 and C2C12 myoblast cells with UCHL1 knockdown were used. Muscle fiber types and size were measured using tissue or cell staining. The mammalian target of rapamycin complex 1 (mTORC1) and mTORC2 activities were assessed with the phosphorylation of their downstream targets. KEY FINDINGS In mouse skeletal muscle, UCHL1 was primarily expressed in slow twitch muscle fibers. Mice with skeletal muscle specific knockout (skmKO) of UCHL1 exhibited enlarged muscle fiber sizes in slow twitch soleus but not fast twitch extensor digitorum longus (EDL) muscle. Meanwhile, UCHL1 skmKO enhanced mTORC1 activity and reduced mTORC2 activity in soleus but not in EDL. Consistently, in C2C12 cells, UCHL1 knockdown increased the myotube size, enhanced mTORC1 activity, and reduced mTORC2 activities as compared with control cells. UCHL1 knockdown did not change the major proteins of mTOR complex but decreased the protein turnover of PRAS40, an inhibitory factor of mTORC1. SIGNIFICANCE These data revealed a novel function of UCHL1 in regulation of mTORC1 activity and skeletal muscle growth in slow twitch skeletal muscle. Given the upregulation of UCHL1 in denervation and spinal muscle atrophy, our finding advances understanding of regulators that are involved in muscle wasting.
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16
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Son K, You JS, Yoon MS, Dai C, Kim JH, Khanna N, Banerjee A, Martinis SA, Han G, Han JM, Kim S, Chen J. Nontranslational function of leucyl-tRNA synthetase regulates myogenic differentiation and skeletal muscle regeneration. J Clin Invest 2019; 129:2088-2093. [PMID: 30985292 DOI: 10.1172/jci122560] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 03/07/2019] [Indexed: 01/29/2023] Open
Abstract
Aside from its catalytic function in protein synthesis, leucyl-tRNA synthetase (LRS) has a nontranslational function in regulating cell growth via the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) pathway by sensing amino acid availability. mTOR also regulates skeletal myogenesis, but the signaling mechanism is distinct from that in cell growth regulation. A role of LRS in myogenesis has not been reported. Here we report that LRS negatively regulated myoblast differentiation in vitro. This function of LRS was independent of its regulation of protein synthesis, and it required leucine-binding but not tRNA charging activity of LRS. Local knock down of LRS accelerated muscle regeneration in a mouse injury model, and so did the knock down of Rag or Raptor. Further in vitro studies established a Rag-mTORC1 pathway, which inhibits the IRS1-PI3K-Akt pathway, to be the mediator of the nontranslational function of LRS in myogenesis. BC-LI-0186, an inhibitor reported to disrupt LRS-Rag interaction, promoted robust muscle regeneration with enhanced functional recovery, and this effect was abolished by cotreatment with an Akt inhibitor. Taken together, our findings revealed what we believe is a novel function for LRS in controlling the homeostasis of myogenesis, and suggested a potential therapeutic strategy to target a noncanonical function of a housekeeping protein.
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Affiliation(s)
- Kook Son
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Illinois, USA
| | - Jae-Sung You
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Illinois, USA
| | - Mee-Sup Yoon
- Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, South Korea
| | - Chong Dai
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Illinois, USA
| | - Jong Hyun Kim
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Nidhi Khanna
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Illinois, USA
| | - Aditi Banerjee
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Illinois, USA
| | - Susan A Martinis
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Illinois, USA
| | - Gyoonhee Han
- Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul, South Korea
| | - Jung Min Han
- College of Pharmacy, Yonsei University, Incheon, South Korea
| | - Sunghoon Kim
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Illinois, USA
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17
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Han H, Qi R, Zhou JJ, Ta AP, Yang B, Nakaoka HJ, Seo G, Guan KL, Luo R, Wang W. Regulation of the Hippo Pathway by Phosphatidic Acid-Mediated Lipid-Protein Interaction. Mol Cell 2018; 72:328-340.e8. [PMID: 30293781 PMCID: PMC6195446 DOI: 10.1016/j.molcel.2018.08.038] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/04/2018] [Accepted: 08/23/2018] [Indexed: 12/14/2022]
Abstract
The Hippo pathway plays a crucial role in organ size control and tumor suppression, but its precise regulation is not fully understood. In this study, we discovered that phosphatidic acid (PA)-related lipid signaling is a key regulator of the Hippo pathway. Supplementing PA in various Hippo-activating conditions activates YAP. This PA-related lipid signaling is involved in Rho-mediated YAP activation. Mechanistically, PA directly interacts with Hippo components LATS and NF2 to disrupt LATS-MOB1 complex formation and NF2-mediated LATS membrane translocation and activation, respectively. Inhibition of phospholipase D (PLD)-dependent PA production suppresses YAP oncogenic activities. PLD1 is highly expressed in breast cancer and positively correlates with YAP activation, suggesting their pathological relevance in breast cancer development. Taken together, our study not only reveals a role of PLD-PA lipid signaling in regulating the Hippo pathway but also indicates that the PLD-PA-YAP axis is a potential therapeutic target for cancer treatment.
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Affiliation(s)
- Han Han
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Ruxi Qi
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Jeff Jiajing Zhou
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Albert Paul Ta
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Bing Yang
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Hiroki J Nakaoka
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Gayoung Seo
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ray Luo
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Wenqi Wang
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA.
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18
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Li H, Xu W, Ma Y, Zhou S, Xiao R. Milk fat globule membrane protein promotes C 2C 12 cell proliferation through the PI3K/Akt signaling pathway. Int J Biol Macromol 2018; 114:1305-1314. [PMID: 29634969 DOI: 10.1016/j.ijbiomac.2018.04.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 11/25/2022]
Abstract
Milk fat globule membrane (MFGM) protein is known to have several health benefits, including an anti-sarcopenia effect; however, its mechanism is unclear. The aim of this study was to investigate the potential mechanism of action of the MFGM protein. The MFGM protein was extracted and separated into 4 fractions, and Fraction 2 (57% of total MFGM) demonstrated the greatest effect on C2C12 cell proliferation. Milk fat globule-EGF factor 8 (MFG-E8) accounted for 82.35% of the MFGM protein. The effects of whole Fraction 2 (100μg/mL, 200μg/mL and 300μg/mL) on cell proliferation and morphology were measured. Using qRT-PCR or a Western blot assay, several regulatory factors, e.g., PI3K P85α, p-pI3K p85α (Tyr 508), Akt, p-Akt (Ser 473), mTOR and p-mTOR (Ser 2448), were measured in cells incubated with 200μg/mL of Fraction 2 with or without wortmannin. The results demonstrated that Fraction 2 induced C2C12 cell proliferation in a dose-dependent manner, upregulated the mRNA expression of mTOR and p70S6K, and activated PI3K, Akt, mTOR and P70S6K phosphorylation; however, Fraction 2 inhibited FOXO3a and 4E-BP. The results demonstrate that the MFGM protein, predominantly MFG-E8, promotes cell proliferation through the PI3K/Akt/mTOR signaling pathway. This study elucidated the molecular mechanism of the MFGM protein, primarily MFG-E8, in promoting C2C12 cell proliferation via the PI3K/Akt/mTOR/P70S6K signal pathway.
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Affiliation(s)
- He Li
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150090, Heilongjiang, PR China
| | - Weili Xu
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150090, Heilongjiang, PR China
| | - Ying Ma
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150090, Heilongjiang, PR China.
| | - Shaobo Zhou
- School of Life Sciences, Institute of Biomedical and Environmental Science and Technology, University of Bedfordshire, Luton LU1 3JU, UK.
| | - Ran Xiao
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150090, Heilongjiang, PR China
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19
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Sato Y, Sato Y, Suzuki R, Obeng K, Yoshizawa F. Leucyl-tRNA synthetase is required for the myogenic differentiation of C2C12 myoblasts, but not for hypertrophy or metabolic alteration of myotubes. Exp Cell Res 2018; 364:184-190. [PMID: 29425714 DOI: 10.1016/j.yexcr.2018.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/01/2018] [Accepted: 02/03/2018] [Indexed: 11/24/2022]
Abstract
Mammalian target of rapamycin (mTOR) signaling controls skeletal muscle cell differentiation, growth, and metabolism by sensing the intracellular energy status and nutrients. Recently, leucyl-tRNA synthetase (Lars) was identified as an intracellular sensor of leucine involved in the activation of mTOR signaling. However, there is still no evidence for the activation of mTOR signaling by Lars and its physiological roles in skeletal muscle cells. In this study, we determined the potential roles of Lars for the activation of mTOR signaling, skeletal muscle cell differentiation, hypertrophy, and metabolism using small interfering (si)-RNA knockdown. siRNA-mediated knockdown of Lars decreased phosphorylated p70 S6 kinase and inhibited the differentiation of C2C12 mouse myoblasts into myotubes, as evidenced by a decreased fusion index and decreased mRNA and protein expression levels of myogenic markers. Importantly, si-Lars decreased the level of Insulin-like growth factor 2 (Igf2) mRNA expression from the early stages of differentiation, indicating the possibility of an association between the mTOR-IGF2 axis and Lars. However, Lars knockdown did not decrease phosphorylated mTOR in differentiated myotubes, nor did it affect the hypertrophy of myotubes as evidenced by measuring their diameters and detecting the mRNA and protein expression of hypertrophy markers. Similarly, an extracellular flux analyzer showed that Lars knockdown did not affect the metabolism (glycolysis and mitochondrial respiration) of myotubes. These results demonstrate that Lars is required for skeletal muscle differentiation through the activation of mTOR signaling, but not for hypertrophy or metabolic alteration of myotubes.
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Affiliation(s)
- Yoriko Sato
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Yusuke Sato
- Department of Agrobiology and Bioresources, Utsunomiya University, 350 Minemachi, Tochigi, Japan.
| | - Reiko Suzuki
- Department of Agrobiology and Bioresources, Utsunomiya University, 350 Minemachi, Tochigi, Japan
| | - Kodwo Obeng
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Fumiaki Yoshizawa
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan; Department of Agrobiology and Bioresources, Utsunomiya University, 350 Minemachi, Tochigi, Japan
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20
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Guo CY, Yu MX, Dai JM, Pan SN, Lu ZT, Qiu XS, Zhuang SQ. Roles of Mitogen-Activating Protein Kinase Kinase Kinase Kinase-3 (MAP4K3) in Preterm Skeletal Muscle Satellite Cell Myogenesis and Mammalian Target of Rapamycin Complex 1 (mTORC1) Activation Regulation. Med Sci Monit 2017; 23:3562-3570. [PMID: 28731988 PMCID: PMC5536126 DOI: 10.12659/msm.902553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background Preterm skeletal muscle genesis is a paradigm for myogenesis. The role of mitogen-activating protein kinase kinase kinase kinase-3 (MAP4K3) in preterm skeletal muscle satellite cells myogenesis or its relationship to mammalian target of rapamycin complex 1 (mTORC1) activity have not been previously elaborated. Material/Methods Small interfering RNA (siRNA) interference technology was used to inhibit MAP4K3 expression. Leucine stimulation experiments were performed following MAP4K3-siRNA interference. The differentiation of primary preterm skeletal muscle satellite cells was observed after siRNA-MAP4K3 interference. Western blot analysis was used to determine the expression of MAP4K3, MyHC, MyoD, myogenin, p-mTOR, and p-S6K1. The immunofluorescence fusion index of MyHC and myogenin were detected. MAP4K3 effects on preterm rat satellite cells differentiation and its relationship to mTORC1 activity are reported. Results MAP4K3 siRNA knockdown inhibited myotube formation and both MyoD and myogenin expression in primary preterm rat skeletal muscle satellite cells, but MAP4K3 siRNA had no effect on the activity of mTORC1. In primary preterm rat skeletal muscle satellite cells, MAP4K3 knockdown resulted in significantly weaker, but not entirely blunted, leucine-induced mTORC1 signaling. Conclusions MAP4K3 positively regulates preterm skeletal muscle satellite cell myogenesis, but may not regulate mTORC1 activity. MAP4K3 may play a role in mTORC1 full activation in response to leucine.
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Affiliation(s)
- Chu-Yi Guo
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Mu-Xue Yu
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Jie-Min Dai
- Department of Pediatrics, Maternal and Child Health Hospital of Foshan City, Foshan, Guangdong, China (mainland)
| | - Si-Nian Pan
- Department of Pediatrics, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Zhen-Tong Lu
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Xiao-Shan Qiu
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Si-Qi Zhuang
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
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21
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Gao CQ, Xu YL, Jin CL, Hu XC, Li HC, Xing GX, Yan HC, Wang XQ. Differentiation capacities of skeletal muscle satellite cells in Lantang and Landrace piglets. Oncotarget 2017; 8:43192-43200. [PMID: 28574820 PMCID: PMC5522138 DOI: 10.18632/oncotarget.17860] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 04/03/2017] [Indexed: 01/31/2023] Open
Abstract
We isolated and cultured satellite cells (SCs) from the longissimus dorsi muscles of 1-day-old male Landrace and Lantang piglets to compare the SC differentiation capacity in the two breeds. Lantang piglets yielded more (P < 0.05) SCs per gram of muscle than Landrace piglets (5.2 ± 0.9×104 vs. 2.4 ± 0.2×104). Transcription of the differentiation markers myogenin and myosin heavy chain I (MyHC I) in the longissimus dorsi muscle was higher in Lantang than Landrace piglets (P < 0.05). Protein levels of myogenin (P < 0.05), MyHC I (P < 0.05), and myogenic regulatory factor 4 (P = 0.07) were higher in Lantang than Landrace piglet SCs after 72 h of differentiation. Creatine kinase activity was higher in Lantang than Landrace piglet SCs after 24, 48, and 72 h of differentiation (P < 0.05), and there was a greater fusion index in Landrace piglet SCs after 72 h of differentiation. In addition, phosphorylation of Akt, mTOR, S6K1, S6, and 4EBP1 was lower in Lantang than Landrace piglet SCs (P < 0.05). Thus differentiation was more extensive in Lantang than Landrace piglet SCs, but expression of the mTOR signaling pathway was lower in Lantang piglet SCs, suggesting mTOR signaling may inhibit myogenic differentiation. These findings reveal that mTOR signaling is a factor in myogenesis and imply that mTOR could potentially serve as an activator of myoblast differentiation and muscle regeneration.
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Affiliation(s)
- Chun-Qi Gao
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China
| | - Yin-Long Xu
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China
- Guangzhou United Bio-Technology Feed Co., Ltd, Guangzhou, China
| | - Cheng-Long Jin
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China
| | - Xiao-Chao Hu
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China
| | - Hai-Chang Li
- Davis Heart & Lung Research Institute, Wexner Medical Center at the Ohio State University, Columbus, OH, USA
| | - Guang-Xu Xing
- Key Laboratory of Animal Immunology of the Ministry of Agriculture, Henan Academy of Agricultural Sciences, Zhengzhou, China
| | - Hui-Chao Yan
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China
| | - Xiu-Qi Wang
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China
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22
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The intricate regulation and complex functions of the Class III phosphoinositide 3-kinase Vps34. Biochem J 2017; 473:2251-71. [PMID: 27470591 DOI: 10.1042/bcj20160170] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 03/30/2016] [Indexed: 11/17/2022]
Abstract
The Class III phosphoinositide 3-kinase Vps34 (vacuolar protein sorting 34) plays important roles in endocytic trafficking, macroautophagy, phagocytosis, cytokinesis and nutrient sensing. Recent studies have provided exciting new insights into the structure and regulation of this lipid kinase, and new cellular functions for Vps34 have emerged. This review critically examines the wealth of new data on this important enzyme, and attempts to integrate these findings with current models of Vps34 signalling.
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23
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FoxO3a suppression and VPS34 activity are essential to anti-atrophic effects of leucine in skeletal muscle. Cell Tissue Res 2017; 369:381-394. [PMID: 28436000 DOI: 10.1007/s00441-017-2614-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 03/21/2017] [Indexed: 12/30/2022]
Abstract
Our aim is to gain insight into the mechanisms underlying the anti-atrophic effects of leucine, namely, the way that this amino acid can restrain the up-regulation of MuRF1 and Mafbx/Atrogin-1 in muscle atrophy. Male rats received dietary leucine supplementation for 1-3 days, during which time their hind limbs were immobilized. Our results showed that leucine inhibited Forkhead Box O3 (FoxO3a) translocation to cell nuclei. In addition, leucine was able to reverse the expected reduction of FoXO3a ubiquitination caused by immobilization. Unexpectedly, leucine promoted these effects independently of the Class I PI3K/Akt pathway. Vacuolar protein sorting 34 (VPS34; a Class III PI3K) was strongly localized in nuclei after immobilization and leucine supplementation was able to prevent this effect. In experiments on cultured primary myotubes, dexamethasone led to the localization of VPS34 in the nucleus. In addition, the pharmacological inhibition of VPS34 blocked VPS34 nuclear localization and impaired the protective effect of leucine upon myotube trophicity. Finally, the pharmacological inhibition of VPS34 in primary myotubes prevented the protective effects of leucine upon MuRF1 and Mafbx/Atrogin-1 gene expression. Autophagy-related target genes were not responsive to leucine. Thus, we demonstrate that the anti-atrophic effect of leucine is dependent upon FoxO3a suppression and VPS34 activity.
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24
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Invited review: impact of specific nutrient interventions during mid-to-late gestation on physiological traits important for survival of multiple-born lambs. Animal 2017; 11:1727-1736. [PMID: 28222833 DOI: 10.1017/s1751731117000313] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
To improve production efficiency, the sheep meat industry has increased flock prolificacy. However, multiple-born lambs have lower birth weights, increased mortality and reduced growth rate compared with single-born lambs. Lamb mortality is a major issue for livestock farming globally and solutions are required to increase survival to realise the value of increased flock fecundity. Nutrition during gestation can influence maternal-foetal placental nutrient transfer and thus foetal growth and organ/tissue development, as well as improve postnatal productivity. This review covers the challenges and opportunities associated with increased prolificacy, highlights gaps in our knowledge and identifies some opportunities for how targeted intervention with specific nutrients during mid-to-late pregnancy may influence lamb survival and productivity with a specific focus on pasture-based systems. This time frame was selected as intervention strategies in short-time windows post-pregnancy scanning and before lambing to improve lamb survival in high-risk groups (e.g. triplets) are likely to be the most practical and economically feasible options for pasture-based extensive farming systems.
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25
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Zhang Y, Yu B, He J, Chen D. From Nutrient to MicroRNA: a Novel Insight into Cell Signaling Involved in Skeletal Muscle Development and Disease. Int J Biol Sci 2016; 12:1247-1261. [PMID: 27766039 PMCID: PMC5069446 DOI: 10.7150/ijbs.16463] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/19/2016] [Indexed: 12/17/2022] Open
Abstract
Skeletal muscle is a remarkably complicated organ comprising many different cell types, and it plays an important role in lifelong metabolic health. Nutrients, as an external regulator, potently regulate skeletal muscle development through various internal regulatory factors, such as mammalian target of rapamycin (mTOR) and microRNAs (miRNAs). As a nutrient sensor, mTOR, integrates nutrient availability to regulate myogenesis and directly or indirectly influences microRNA expression. MiRNAs, a class of small non-coding RNAs mediating gene silencing, are implicated in myogenesis and muscle-related diseases. Meanwhile, growing evidence has emerged supporting the notion that the expression of myogenic miRNAs could be regulated by nutrients in an epigenetic mechanism. Therefore, this review presents a novel insight into the cell signaling network underlying nutrient-mTOR-miRNA pathway regulation of skeletal myogenesis and summarizes the epigenetic modifications in myogenic differentiation, which will provide valuable information for potential therapeutic intervention.
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Affiliation(s)
- Yong Zhang
- Institute of Animal Nutrition, Sichuan Agricultural University, Ya'an, Sichuan 625014, P. R. China.; Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, China
| | - Bing Yu
- Institute of Animal Nutrition, Sichuan Agricultural University, Ya'an, Sichuan 625014, P. R. China.; Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, China
| | - Jun He
- Institute of Animal Nutrition, Sichuan Agricultural University, Ya'an, Sichuan 625014, P. R. China.; Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, China
| | - Daiwen Chen
- Institute of Animal Nutrition, Sichuan Agricultural University, Ya'an, Sichuan 625014, P. R. China.; Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, China
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26
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Tu C, Bu Y, Vujcic M, Shen S, Li J, Qu M, Hangauer D, Clements JL, Qu J. Ion Current-Based Proteomic Profiling for Understanding the Inhibitory Effect of Tumor Necrosis Factor Alpha on Myogenic Differentiation. J Proteome Res 2016; 15:3147-57. [PMID: 27480135 DOI: 10.1021/acs.jproteome.6b00321] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite a demonstrated role for TNF-α in promoting muscle wasting and cachexia, the associated molecular mechanisms and signaling pathways of myoblast differentiation dysregulated by TNF-α remain poorly understood. This study presents well-controlled proteomic profiling as a means to investigate the mechanisms of TNF-α-regulated myogenic differentiation. Primary human muscle precursor cells (MPCs) cultured in growth medium (GM), differentiation medium (DM) to induce myogenic differentiation, and DM with 20 ng/mL of TNF-α (n = 5/group) were comparatively analyzed by an ion current-based quantitative platform consisting of reproducible sample preparation/on-pellet digestion, a long-column nano-LC separation, and ion current-based differential analysis. The inhibition of myogenic differentiation by TNF-α was confirmed by reduced formation of multinucleated myotubes and the recovered expression of altered myogenic proteins such as MYOD and myogenin during myogenic differentiation. Functional analysis and validation by immunoassay analysis suggested that the cooperation of NF-κB and STAT proteins is responsible for dysregulated differentiation in MPCs by TNF-α treatment. Increased MHC class I components such as HLA-A, HLA-B, HLA-C, and beta-2-microglobulin were also observed in cultures in DM treated with TNF-α. Interestingly, inhibition of the cholesterol biosynthesis pathway during myogenic differentiation induced by serum starvation was not recovered by TNF-α treatment, which combined with previous reports, implies that this process may be an early event of myogenesis. This finding could lay the foundation for the potential use of statins in modulating myogenesis through cholesterol, for example, in stem cell-based myocardial infarction treatment, where differentiation of myoblasts and stem cells into force-generating mature muscle cells is a key step to the therapeutic capacity. In conclusion, the landscapes of altered transcription regulators, metabolic processes, and signaling pathways in MPCs are revealed in the regulation of myogenic differentiation by TNF-α, which is valuable for myogenic cellular therapeutics.
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Affiliation(s)
- Chengjian Tu
- Department of Pharmaceutical Sciences, State University of New York at Buffalo , 285 Kapoor Hall, Buffalo, New York 14260, United States.,New York State Center of Excellence in Bioinformatics and Life Sciences , 701 Ellicott Street, Buffalo, New York 14203, United States
| | - Yahao Bu
- Athenex Pharmaceuticals, 1001 Main Street, Suite 600, Buffalo, New York 14203, United States
| | - Marija Vujcic
- Athenex Pharmaceuticals, 1001 Main Street, Suite 600, Buffalo, New York 14203, United States
| | - Shichen Shen
- Department of Pharmaceutical Sciences, State University of New York at Buffalo , 285 Kapoor Hall, Buffalo, New York 14260, United States.,New York State Center of Excellence in Bioinformatics and Life Sciences , 701 Ellicott Street, Buffalo, New York 14203, United States
| | - Jun Li
- Department of Pharmaceutical Sciences, State University of New York at Buffalo , 285 Kapoor Hall, Buffalo, New York 14260, United States.,New York State Center of Excellence in Bioinformatics and Life Sciences , 701 Ellicott Street, Buffalo, New York 14203, United States
| | - Miao Qu
- Department of Pharmaceutical Sciences, State University of New York at Buffalo , 285 Kapoor Hall, Buffalo, New York 14260, United States.,Beijing University of Chinese Medicine , Beijing, 100029, China
| | - David Hangauer
- Athenex Pharmaceuticals, 1001 Main Street, Suite 600, Buffalo, New York 14203, United States
| | - James L Clements
- Athenex Pharmaceuticals, 1001 Main Street, Suite 600, Buffalo, New York 14203, United States
| | - Jun Qu
- Department of Pharmaceutical Sciences, State University of New York at Buffalo , 285 Kapoor Hall, Buffalo, New York 14260, United States.,New York State Center of Excellence in Bioinformatics and Life Sciences , 701 Ellicott Street, Buffalo, New York 14203, United States
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27
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Brown LD, Wesolowski SR, Kailey J, Bourque S, Wilson A, Andrews SE, Hay WW, Rozance PJ. Chronic Hyperinsulinemia Increases Myoblast Proliferation in Fetal Sheep Skeletal Muscle. Endocrinology 2016; 157:2447-60. [PMID: 27049667 PMCID: PMC4891788 DOI: 10.1210/en.2015-1744] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Insulin is an important fetal growth factor. However, chronic experimental hyperinsulinemia in the fetus fails to accelerate linear and lean mass growth beyond normal rates. Mechanisms preventing accelerated lean mass accretion during hyperinsulinemia are unknown. To address potential mechanisms, late-gestation fetal sheep were infused with iv insulin and glucose to produce euglycemic hyperinsulinemia (INS) or saline for 7-9 days. Fetal substrate uptake and protein metabolic rates were measured. INS fetuses had 1.5-fold higher insulin concentrations (P < .0001) and equivalent glucose concentrations. INS fetuses had 20% more Pax7(+) nuclei in the biceps femoris, which indicates the potential for hyperinsulinemia to increase the number of myoblasts within late-gestation fetal skeletal muscle. Additionally, the percentage of Pax7(+) myoblasts that expressed Ki-67 was 1.3-fold higher and expression of myogenic regulatory factors was 50% lower in INS fetuses (MYF5 and MYOG [myogenin], P < .005), which indicates a shift toward myoblast proliferation over differentiation. There were no differences for fetal body, organ, or muscle weights, although INS placentas weighed 28% less (P < .05). Protein synthesis and accretion rates did not change in INS fetuses, nor did fiber muscle size. Essential amino acid concentrations were lower in the INS group (P < .05) except for tryptophan. Umbilical blood flow, net total amino acids, and O2 uptakes rates did not differ between groups. Arterial O2 content was 33% lower (P < .005) and norepinephrine was 100% higher in the INS fetuses (P < .01), all of which are factors that may counteract fetal protein accretion during hyperinsulinemia despite an increase in myoblast proliferation.
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Affiliation(s)
- Laura D Brown
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Stephanie R Wesolowski
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Jenai Kailey
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Stephanie Bourque
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Averi Wilson
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Sasha E Andrews
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - William W Hay
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Paul J Rozance
- Perinatal Research Center (L.D.B., S.R.W., J.K., S.B., A.W., W.W.H., P.J.R.), Department of Pediatrics, Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), and Department of Obstetrics and Gynecology (S.E.A.), University of Colorado Denver School of Medicine, Aurora, Colorado 80045
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Xia Z, Cholewa J, Zhao Y, Yang YQ, Shang HY, Guimarães-Ferreira L, Naimo MA, Su QS, Zanchi NE. Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice. Nutrients 2016; 8:nu8050246. [PMID: 27144582 PMCID: PMC4882659 DOI: 10.3390/nu8050246] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Revised: 04/19/2016] [Accepted: 04/20/2016] [Indexed: 01/01/2023] Open
Abstract
Several studies have indicated a positive influence of leucine supplementation and aerobic training on the aging skeletal muscle signaling pathways that control muscle protein balance and muscle remodeling. However, the effect of a combined intervention requires further clarification. Thirteen month old CD-1® mice were subjected to moderate aerobic exercise (45 min swimming per day with 3% body weight workload) and fed a chow diet with 5% leucine or 3.4% alanine for 8 weeks. Serum and plasma were prepared for glucose, urea nitrogen, insulin and amino acid profile analysis. The white gastrocnemius muscles were used for determination of muscle size and signaling proteins involved in protein synthesis and degradation. The results show that both 8 weeks of leucine supplementation and aerobic training elevated the activity of mTOR (mammalian target of rapamycin) and its downstream target p70S6K and 4E-BP1, inhibited the ubiquitin-proteasome system, and increased fiber cross-sectional area (CSA) in white gastrocnemius muscle. Moreover, leucine supplementation in combination with exercise demonstrated more significant effects, such as greater CSA, protein content and altered phosphorylation (suggestive of increased activity) of protein synthesis signaling proteins, in addition to lower expression of proteins involved in protein degradation compared to leucine or exercise alone. The current study shows moderate aerobic training combined with 5% leucine supplementation has the potential to increase muscle size in fast-twitch skeletal muscle during aging, potentially through increased protein synthesis and decreased protein breakdown.
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Affiliation(s)
- Zhi Xia
- Exercise Physiology and Biochemistry Laboratory, College of Physical Education, Jinggangshan University, Ji'an 343009, China.
- Exercise Intervention and Health Promotion Hubei Province Synergy Innovation Center, Wuhan Sports University, Wuhan 430079, China.
| | - Jason Cholewa
- Department of Kinesiology, Coastal Carolina University, Conway, SC 29528-6054, USA.
| | - Yan Zhao
- Exercise Physiology and Biochemistry Laboratory, College of Physical Education, Jinggangshan University, Ji'an 343009, China.
| | - Yue-Qin Yang
- Exercise Intervention and Health Promotion Hubei Province Synergy Innovation Center, Wuhan Sports University, Wuhan 430079, China.
| | - Hua-Yu Shang
- Exercise Physiology Laboratory, Department of Exercise Physiology, Beijing Sport University, Beijing 100084, China.
| | - Lucas Guimarães-Ferreira
- Muscle Physiology and Human Performance Research Group, Center of Physical Education and Sports, Federal University of Espirito Santo, Vitória/ES 29075-810, Brazil.
| | - Marshall Alan Naimo
- Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506-9227, USA.
| | - Quan-Sheng Su
- Department of Sports Medicine, Chengdu Sport University, Chengdu 610041, China.
| | - Nelo Eidy Zanchi
- Department of Physical Education, Federal University of Maranhão (UFMA), São Luís-MA 65020-070, Brazil.
- Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME), São Luís-MA 65020-070, Brazil.
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29
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Chistiakov DA, Orekhov AN, Bobryshev YV. Cardiac-specific miRNA in cardiogenesis, heart function, and cardiac pathology (with focus on myocardial infarction). J Mol Cell Cardiol 2016; 94:107-121. [PMID: 27056419 DOI: 10.1016/j.yjmcc.2016.03.015] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/09/2016] [Accepted: 03/24/2016] [Indexed: 12/21/2022]
Abstract
Cardiac miRNAs (miR-1, miR133a, miR-208a/b, and miR-499) are abundantly expressed in the myocardium. They play a central role in cardiogenesis, heart function and pathology. While miR-1 and miR-133a predominantly control early stages of cardiogenesis supporting commitment of cardiac-specific muscle lineage from embryonic stem cells and mesodermal precursors, miR-208 and miR-499 are involved in the late cardiogenic stages mediating differentiation of cardioblasts to cardiomyocytes and fast/slow muscle fiber specification. In the heart, miR-1/133a control cardiac conductance and automaticity by regulating all phases of the cardiac action potential. miR-208/499 located in introns of the heavy chain myosin genes regulate expression of sarcomeric contractile proteins. In cardiac pathology including myocardial infarction (MI), expression of cardiac miRNAs is markedly altered that leads to deleterious effects associated with heart wounding, arrhythmia, increased apoptosis, fibrosis, hypertrophy, and tissue remodeling. In acute MI, circulating levels of cardiac miRNAs are significantly elevated making them to be a promising diagnostic marker for early diagnosis of acute MI. Great cardiospecific capacity of these miRNAs is very helpful for enhancing regenerative properties and survival of stem cell and cardiac progenitor transplants and for reprogramming of mature non-cardiac cells to cardiomyocytes.
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Affiliation(s)
- Dimitry A Chistiakov
- Department of Molecular Genetic Diagnostics and Cell Biology, Division of Laboratory Medicine, Institute of Pediatrics, Research Center for Children's Health, 119991 Moscow, Russia
| | - Alexander N Orekhov
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, Moscow 125315, Russia; Department of Biophysics, Biological Faculty, Moscow State University, Moscow 119991, Russia; Institute for Atherosclerosis Research, Skolkovo Innovative Center, Moscow 121609, Russia
| | - Yuri V Bobryshev
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, Moscow 125315, Russia; Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia; School of Medicine, University of Western Sydney, Campbelltown, NSW 2560, Australia.
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30
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Honardoost M, Soleimani M, Arefian E, Sarookhani MR. Expression Change of miR-214 and miR-135 during Muscle Differentiation. CELL JOURNAL 2015; 17:461-70. [PMID: 26464817 PMCID: PMC4601866 DOI: 10.22074/cellj.2015.7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 11/08/2014] [Indexed: 12/20/2022]
Abstract
Objective MicroRNAs (miRNAs) are a class of small non-coding RNAs that play pivotal
roles in many biological processes such as regulating skeletal muscle development where
alterations in miRNA expression are reported during myogenesis. In this study, we aimed
to investigate the impact of predicted miRNAs and their target genes on the myoblast to
myocyte differentiation process.
Materials and Methods This experimental study was conducted on the C2C12 cell line.
Using a bioinformatics approach, miR-214 and miR-135 were selected according to their
targets as potential factors in myoblast to myocyte differentiation induced by 3% horse
serum. Immunocytochemistry (ICC) was undertaken to confirm the differentiation process
and quantitative real-time polymerase chain reaction (PCR) to determine the expression
level of miRNAs and their targets.
Results During myoblast to myocyte differentiation, miR-214 was significantly down-
regulated while miRNA-135, Irs2, Akt2 and Insr were overexpressed during the process.
Conclusion miR-214 and miR-135 are potential regulators of myogenesis and are
involved in skeletal muscle development through regulating the IRS/PI3K pathway.
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Affiliation(s)
- Maryam Honardoost
- Department of Molecular Medicine, School of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran ; Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran ; Department of Molecular Biology and Genetic Engineering, Stem Cell Technology Research Center, Tehran, Iran
| | - Masoud Soleimani
- Department of Hematology, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Ehsan Arefian
- Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Mohammad Reza Sarookhani
- Department of Molecular Medicine, School of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran ; Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
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Del Vesco AP, Gasparino E, Grieser DO, Zancanela V, Voltolini DM, Khatlab AS, Guimarães SEF, Soares MAM, Neto ARO. Effects of methionine supplementation on the expression of protein deposition-related genes in acute heat stress-exposed broilers. PLoS One 2015; 10:e0115821. [PMID: 25714089 PMCID: PMC4340924 DOI: 10.1371/journal.pone.0115821] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/02/2014] [Indexed: 11/20/2022] Open
Abstract
The objective of this study was to evaluate the effect of heat stress and methionine supplementation on the gene expression of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), phosphatidylinositol 3-kinase, and regulatory 1 (PI3KR1) in the liver, as well as the expression of the atrogin 1 and cathepsin L2 (CTSL2) genes in the breast muscle of broilers. Broilers from 1–21 and 22–42 days of age were divided into three treatments related to methionine supplementation as follows: without methionine supplementation (MD), recommended level of methionine (DL1), and excess supplementation of methionine (DL2). The animals were either maintained at a thermal comfort temperature or exposed to heat stress (HS) (38°C for 24 hours, starting on day 20 or day 41 for experiments 1 and 2, respectively). The heat stress increased the body temperature at both ages. Starter period: The HS animals presented increased plasma creatinine content (P<0.0001) and the highest CTSL2 gene expression (P<0.0001). The methionine supplementation increased the IGF-I (P = 0.0144) and GHR (P = 0.0011) gene expression and decreased the CTSL2 (P = 0.0004) and atrogin 1 (P = 0.0012) gene expression. Grower period: Significant effects for the interaction between supplementation and environment were observed for GHR (P = 0.0252) and CTSL2 (P = 0.0011) gene expression. The highest GHR expression was observed in animals that remained in thermal comfort on the DL2 diet, and the lowest expression occurred in the HS animals fed the MD diet. For CTSL2, the HS animals fed the MD diet presented the highest CTSL2 gene expression, and the lowest expression was observed in the animals maintained at thermal comfort on DL1 and DL2 diets. Only methionine supplementation had effect on atrogin-1 gene expression (P<0.0001), with higher methionine content in the diet lower atrogin-1 gene expression was observed. Our results suggest that heat stress induces greater protein degradation and that methionine supplementation could induce protein deposition because methionine increased the expression of genes related to protein synthesis and decreased the expression of genes related to protein breakdown.
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Affiliation(s)
- Ana Paula Del Vesco
- Department of Animal Science, Universidade Estadual de Maringá—UEM—Maringá, Paraná, Brazil
- * E-mail: (EG); (APDV)
| | - Eliane Gasparino
- Department of Animal Science, Universidade Estadual de Maringá—UEM—Maringá, Paraná, Brazil
- * E-mail: (EG); (APDV)
| | | | - Vittor Zancanela
- Department of Animal Science, Universidade Estadual de Maringá—UEM—Maringá, Paraná, Brazil
| | | | - Angélica Souza Khatlab
- Department of Animal Science, Universidade Estadual de Maringá—UEM—Maringá, Paraná, Brazil
| | | | - Maria Amélia Menck Soares
- Department of Genetics, Universidade Federal Rural do Rio de Janeiro—UFRRJ—Seropédica, Rio de Janeiro, Brazil
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Frohman MA. The phospholipase D superfamily as therapeutic targets. Trends Pharmacol Sci 2015; 36:137-44. [PMID: 25661257 DOI: 10.1016/j.tips.2015.01.001] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/11/2015] [Accepted: 01/13/2015] [Indexed: 01/03/2023]
Abstract
The phospholipase D (PLD) lipid-signaling enzyme superfamily has long been studied for its roles in cell communication and a wide range of cell biological processes. With the advent of loss-of-function genetic mouse models that have revealed that PLD1 and PLD2 ablation is overtly tolerable, small-molecule PLD1/2 inhibitors that do not cause unacceptable clinical toxicity, a PLD2 polymorphism that has been linked to altered physiology, and growing delineation of processes that are subtly altered in mice lacking PLD1/2 activity, the stage is being set for assessment of PLD1/2 inhibition for therapeutic purposes. Based on findings to date, PLD1/2 inhibition may be of more utility in acute rather than chronic settings, although this generalization will depend on the specific risks and benefits in each disease setting.
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Affiliation(s)
- Michael A Frohman
- Department of Pharmacological Sciences and the Center for Developmental Genetics, 438 Centers for Molecular Medicine, Stony Brook University, Stony Brook, NY 11794-5140, USA.
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Bowman CJ, Ayer DE, Dynlacht BD. Foxk proteins repress the initiation of starvation-induced atrophy and autophagy programs. Nat Cell Biol 2014; 16:1202-14. [PMID: 25402684 PMCID: PMC4250422 DOI: 10.1038/ncb3062] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/13/2014] [Indexed: 12/14/2022]
Abstract
Autophagy is the primary catabolic process triggered in response to starvation. Although autophagic regulation within the cytosolic compartment is well established, it is becoming clear that nuclear events also regulate the induction or repression of autophagy. Nevertheless, a thorough understanding of the mechanisms by which sequence-specific transcription factors modulate expression of genes required for autophagy is lacking. Here, we identify Foxk proteins (Foxk1 and Foxk2) as transcriptional repressors of autophagy in muscle cells and fibroblasts. Interestingly, Foxk1/2 serve to counter-balance another forkhead transcription factor, Foxo3, which induces an overlapping set of autophagic and atrophic targets in muscle. Foxk1/2 specifically recruits Sin3A-HDAC complexes to restrict acetylation of histone H4 and expression of critical autophagy genes. Remarkably, mTOR promotes the transcriptional activity of Foxk1 by facilitating nuclear entry to specifically limit basal levels of autophagy in nutrient-rich conditions. Our study highlights an ancient, conserved mechanism whereby nutritional status is interpreted by mTOR to restrict autophagy by repressing essential autophagy genes via Foxk-Sin3-mediated transcriptional control.
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Affiliation(s)
- Christopher John Bowman
- Department of Pathology, New York University Cancer Institute, New York University School of Medicine, New York, New York 10016, USA
| | - Donald E Ayer
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112, USA
| | - Brian David Dynlacht
- Department of Pathology, New York University Cancer Institute, New York University School of Medicine, New York, New York 10016, USA
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Jia G, Aroor AR, Martinez-Lemus LA, Sowers JR. Overnutrition, mTOR signaling, and cardiovascular diseases. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1198-206. [PMID: 25253086 DOI: 10.1152/ajpregu.00262.2014] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The prevalence of obesity and associated medical disorders has increased dramatically in the United States and throughout much of the world in the past decade. Obesity, induced by excess intake of carbohydrates and fats, is a major cause of Type 2 diabetes, hypertension, and the cardiorenal metabolic syndrome. There is emerging evidence that excessive nutrient intake promotes signaling through the mammalian target of rapamycin (mTOR), which, in turn, may lead to alterations of cellular metabolic signaling leading to insulin resistance and obesity-related diseases, such as diabetes, cardiovascular and kidney disease, as well as cancer. While the pivotal role of mTOR signaling in regulating metabolic stress, autophagy, and adaptive immune responses has received increasing attention, there remain many gaps in our knowledge regarding this important nutrient sensor. For example, the precise cellular signaling mechanisms linking excessive nutrient intake and enhanced mTOR signaling with increased cardiovascular and kidney disease, as well as cancer, are not well understood. In this review, we focus on the effects that the interaction between excess intake of nutrients and enhanced mTOR signaling have on the promotion of obesity-associated diseases and potential therapeutic strategies involving targeting mTOR signaling.
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Affiliation(s)
- Guanghong Jia
- Divisions of Endocrinology, Diabetes, Hypertension and Metabolism, Diabetes Cardiovascular Center, University of Missouri School of Medicine, Columbia, Missouri; Harry S. Truman Memorial Veterans Hospital, University of Missouri School of Medicine, Columbia, Missouri; and
| | - Annayya R Aroor
- Divisions of Endocrinology, Diabetes, Hypertension and Metabolism, Diabetes Cardiovascular Center, University of Missouri School of Medicine, Columbia, Missouri; Harry S. Truman Memorial Veterans Hospital, University of Missouri School of Medicine, Columbia, Missouri; and
| | - Luis A Martinez-Lemus
- Departments of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri; Harry S. Truman Memorial Veterans Hospital, University of Missouri School of Medicine, Columbia, Missouri; and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - James R Sowers
- Divisions of Endocrinology, Diabetes, Hypertension and Metabolism, Diabetes Cardiovascular Center, University of Missouri School of Medicine, Columbia, Missouri; Departments of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri; Harry S. Truman Memorial Veterans Hospital, University of Missouri School of Medicine, Columbia, Missouri; and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
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Shaheen F, Grammatopoulos DK, Müller J, Zammit VA, Lehnert H. Extra-nuclear telomerase reverse transcriptase (TERT) regulates glucose transport in skeletal muscle cells. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1762-9. [PMID: 24970747 DOI: 10.1016/j.bbadis.2014.06.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 05/20/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
Telomerase reverse transcriptase (TERT) is a key component of the telomerase complex. By lengthening telomeres in DNA strands, TERT increases senescent cell lifespan. Mice that lack TERT age much faster and exhibit age-related conditions such as osteoporosis, diabetes and neurodegeneration. Accelerated telomere shortening in both human and animal models has been documented in conditions associated with insulin resistance, including T2DM. We investigated the role of TERT, in regulating cellular glucose utilisation by using the myoblastoma cell line C2C12, as well as primary mouse and human skeletal muscle cells. Inhibition of TERT expression or activity by using siRNA (100nM) or specific inhibitors (100nM) reduced basal 2-deoxyglucose uptake by ~50%, in all cell types, without altering insulin responsiveness. In contrast, TERT over-expression increased glucose uptake by 3.25-fold. In C2C12 cells TERT protein was mostly localised intracellularly and stimulation of cells with insulin induced translocation to the plasma membrane. Furthermore, co-immunoprecipitation experiments in C2C12 cells showed that TERT was constitutively associated with glucose transporters (GLUTs) 1, 4 and 12 via an insulin insensitive interaction that also did not require intact PI3-K and mTOR pathways. Collectively, these findings identified a novel extra-nuclear function of TERT that regulates an insulin-insensitive pathway involved in glucose uptake in human and mouse skeletal muscle cells.
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Affiliation(s)
- Fozia Shaheen
- Division of Metabolic and Vascular Health, Warwick Medical School, Clinical Sciences Research Laboratories, University of Warwick, CV2 2DX, UK.
| | - Dimitris K Grammatopoulos
- Division of Metabolic and Vascular Health, Warwick Medical School, Clinical Sciences Research Laboratories, University of Warwick, CV2 2DX, UK.
| | - Jürgen Müller
- Division of Metabolic and Vascular Health, Warwick Medical School, Clinical Sciences Research Laboratories, University of Warwick, CV2 2DX, UK.
| | - Victor A Zammit
- Division of Metabolic and Vascular Health, Warwick Medical School, Clinical Sciences Research Laboratories, University of Warwick, CV2 2DX, UK.
| | - Hendrik Lehnert
- Division of Metabolic and Vascular Health, Warwick Medical School, Clinical Sciences Research Laboratories, University of Warwick, CV2 2DX, UK; First Department of Medicine, University Hospital of Schleswig-Holstein, Campus Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany.
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