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Ramakrishna S, Radhakrishna BK, Kaladiyil AP, Shah NM, Basavaraju N, Freude KK, Kommaddi RP, Muddashetty RS. Distinct calcium sources regulate temporal profiles of NMDAR and mGluR-mediated protein synthesis. Life Sci Alliance 2024; 7:e202402594. [PMID: 38749544 PMCID: PMC11096670 DOI: 10.26508/lsa.202402594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 05/18/2024] Open
Abstract
Calcium signaling is integral for neuronal activity and synaptic plasticity. We demonstrate that the calcium response generated by different sources modulates neuronal activity-mediated protein synthesis, another process essential for synaptic plasticity. Stimulation of NMDARs generates a protein synthesis response involving three phases-increased translation inhibition, followed by a decrease in translation inhibition, and increased translation activation. We show that these phases are linked to NMDAR-mediated calcium response. Calcium influx through NMDARs elicits increased translation inhibition, which is necessary for the successive phases. Calcium through L-VGCCs acts as a switch from translation inhibition to the activation phase. NMDAR-mediated translation activation requires the contribution of L-VGCCs, RyRs, and SOCE. Furthermore, we show that IP3-mediated calcium release and SOCE are essential for mGluR-mediated translation up-regulation. Finally, we signify the relevance of our findings in the context of Alzheimer's disease. Using neurons derived from human fAD iPSCs and transgenic AD mice, we demonstrate the dysregulation of NMDAR-mediated calcium and translation response. Our study highlights the complex interplay between calcium signaling and protein synthesis, and its implications in neurodegeneration.
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Affiliation(s)
- Sarayu Ramakrishna
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
| | - Bindushree K Radhakrishna
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
- Manipal Academy of Higher Education, Manipal, India
| | - Ahamed P Kaladiyil
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
| | - Nisa Manzoor Shah
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
- Manipal Academy of Higher Education, Manipal, India
| | - Nimisha Basavaraju
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
- Manipal Academy of Higher Education, Manipal, India
| | - Kristine K Freude
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Reddy Peera Kommaddi
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
| | - Ravi S Muddashetty
- https://ror.org/04dese585 Centre for Brain Research, Indian Institute of Science, Bangalore, India
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2
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Xiao G, Li X, Yang H, Zhang R, Huang J, Tian Y, Nie M, Sun X. mTOR mutation disrupts larval zebrafish tail fin regeneration via regulating proliferation of blastema cells and mitochondrial functions. J Orthop Surg Res 2024; 19:321. [PMID: 38812038 PMCID: PMC11134885 DOI: 10.1186/s13018-024-04802-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/21/2024] [Indexed: 05/31/2024] Open
Abstract
BACKGROUND The larval zebrafish tail fin can completely regenerate in 3 days post amputation. mTOR, the main regulator of cell growth and metabolism, plays an essential role in regeneration. Lots of studies have documented the role of mTOR in regeneration. However, the mechanisms involved are still not fully elucidated. MATERIALS AND RESULTS This study aimed to explore the role and mechanism of mTOR in the regeneration of larval zebrafish tail fins. Initially, the spatial and temporal expression of mTOR signaling in the larval fin was examined, revealing its activation following tail fin amputation. Subsequently, a mTOR knockout (mTOR-KO) zebrafish line was created using CRISPR/Cas9 gene editing technology. The investigation demonstrated that mTOR depletion diminished the proliferative capacity of epithelial and mesenchymal cells during fin regeneration, with no discernible impact on cell apoptosis. Insight from SMART-seq analysis uncovered alterations in the cell cycle, mitochondrial functions and metabolic pathways when mTOR signaling was suppressed during fin regeneration. Furthermore, mTOR was confirmed to enhance mitochondrial functions and Ca2 + activation following fin amputation. These findings suggest a potential role for mTOR in promoting mitochondrial fission to facilitate tail fin regeneration. CONCLUSION In summary, our results demonstrated that mTOR played a key role in larval zebrafish tail fin regeneration, via promoting mitochondrial fission and proliferation of blastema cells.
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Affiliation(s)
- Gongyi Xiao
- Center for Joint Surgery, Department of Orthopedic Surgery, The Second Affiliated Hospital of Chongqing Medical University, 74 Linjiang Road, Chongqing, 400010, China
| | - Xiangwei Li
- Center for Joint Surgery, Department of Orthopedic Surgery, The Second Affiliated Hospital of Chongqing Medical University, 74 Linjiang Road, Chongqing, 400010, China
| | - Huiping Yang
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, 74 Linjiang Road, Chongqing, 400010, China
| | - Ruobin Zhang
- Department of Wound Repair and Rehabilitation Medicine, State Key Laboratory of Trauma, Burns and Combined Injury, Trauma Center, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Junlan Huang
- Department of Wound Repair and Rehabilitation Medicine, State Key Laboratory of Trauma, Burns and Combined Injury, Trauma Center, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Yu Tian
- Department of Wound Repair and Rehabilitation Medicine, State Key Laboratory of Trauma, Burns and Combined Injury, Trauma Center, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, 400042, China
- Ministry of Education College of Bioengineering, Chongqing University, Chongqing, 400044, P. R. China
| | - Mao Nie
- Center for Joint Surgery, Department of Orthopedic Surgery, The Second Affiliated Hospital of Chongqing Medical University, 74 Linjiang Road, Chongqing, 400010, China.
| | - Xianding Sun
- Center for Joint Surgery, Department of Orthopedic Surgery, The Second Affiliated Hospital of Chongqing Medical University, 74 Linjiang Road, Chongqing, 400010, China.
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3
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Romagnolo A, Dematteis G, Scheper M, Luinenburg MJ, Mühlebner A, Van Hecke W, Manfredi M, De Giorgis V, Reano S, Filigheddu N, Bortolotto V, Tapella L, Anink JJ, François L, Dedeurwaerdere S, Mills JD, Genazzani AA, Lim D, Aronica E. Astroglial calcium signaling and homeostasis in tuberous sclerosis complex. Acta Neuropathol 2024; 147:48. [PMID: 38418708 PMCID: PMC10901927 DOI: 10.1007/s00401-024-02711-3] [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: 12/06/2023] [Revised: 02/12/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024]
Abstract
Tuberous Sclerosis Complex (TSC) is a multisystem genetic disorder characterized by the development of benign tumors in various organs, including the brain, and is often accompanied by epilepsy, neurodevelopmental comorbidities including intellectual disability and autism. A key hallmark of TSC is the hyperactivation of the mechanistic target of rapamycin (mTOR) signaling pathway, which induces alterations in cortical development and metabolic processes in astrocytes, among other cellular functions. These changes could modulate seizure susceptibility, contributing to the progression of epilepsy and its associated comorbidities. Epilepsy is characterized by dysregulation of calcium (Ca2+) channels and intracellular Ca2+ dynamics. These factors contribute to hyperexcitability, disrupted synaptogenesis, and altered synchronization of neuronal networks, all of which contribute to seizure activity. This study investigates the intricate interplay between altered Ca2+ dynamics, mTOR pathway dysregulation, and cellular metabolism in astrocytes. The transcriptional profile of TSC patients revealed significant alterations in pathways associated with cellular respiration, ER and mitochondria, and Ca2+ regulation. TSC astrocytes exhibited lack of responsiveness to various stimuli, compromised oxygen consumption rate and reserve respiratory capacity underscoring their reduced capacity to react to environmental changes or cellular stress. Furthermore, our study revealed significant reduction of store operated calcium entry (SOCE) along with strong decrease of basal mitochondrial Ca2+ concentration and Ca2+ influx in TSC astrocytes. In addition, we observed alteration in mitochondrial membrane potential, characterized by increased depolarization in TSC astrocytes. Lastly, we provide initial evidence of structural abnormalities in mitochondria within TSC patient-derived astrocytes, suggesting a potential link between disrupted Ca2+ signaling and mitochondrial dysfunction. Our findings underscore the complexity of the relationship between Ca2+ signaling, mitochondria dynamics, apoptosis, and mTOR hyperactivation. Further exploration is required to shed light on the pathophysiology of TSC and on TSC associated neuropsychiatric disorders offering further potential avenues for therapeutic development.
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Affiliation(s)
- Alessia Romagnolo
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands.
| | - Giulia Dematteis
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", Novara, Italy
| | - Mirte Scheper
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Mark J Luinenburg
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Angelika Mühlebner
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Wim Van Hecke
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marcello Manfredi
- Center on Autoimmune and Allergic Diseases (CAAD), UPO, Novara, Italy
- Department of Translational Medicine, UPO, Novara, Italy
| | - Veronica De Giorgis
- Center on Autoimmune and Allergic Diseases (CAAD), UPO, Novara, Italy
- Department of Translational Medicine, UPO, Novara, Italy
| | - Simone Reano
- Center on Autoimmune and Allergic Diseases (CAAD), UPO, Novara, Italy
| | | | - Valeria Bortolotto
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", Novara, Italy
| | - Laura Tapella
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", Novara, Italy
| | - Jasper J Anink
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Liesbeth François
- Neurosciences Therapeutic Area, UCB Pharma, Braine-L'Alleud, Belgium
| | | | - James D Mills
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Clinical and Experimental Epilepsy, UCL, London, UK
- Chalfont Centre for Epilepsy, Chalfont St Peter, UK
| | - Armando A Genazzani
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", Novara, Italy
| | - Dmitry Lim
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", Novara, Italy
| | - Eleonora Aronica
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
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4
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Nguyen HT, Wiederkehr A, Wollheim CB, Park KS. Regulation of autophagy by perilysosomal calcium: a new player in β-cell lipotoxicity. Exp Mol Med 2024; 56:273-288. [PMID: 38297165 PMCID: PMC10907728 DOI: 10.1038/s12276-024-01161-x] [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: 05/03/2023] [Revised: 10/16/2023] [Accepted: 11/09/2023] [Indexed: 02/02/2024] Open
Abstract
Autophagy is an essential quality control mechanism for maintaining organellar functions in eukaryotic cells. Defective autophagy in pancreatic beta cells has been shown to be involved in the progression of diabetes through impaired insulin secretion under glucolipotoxic stress. The underlying mechanism reveals the pathologic role of the hyperactivation of mechanistic target of rapamycin (mTOR), which inhibits lysosomal biogenesis and autophagic processes. Moreover, accumulating evidence suggests that oxidative stress induces Ca2+ depletion in the endoplasmic reticulum (ER) and cytosolic Ca2+ overload, which may contribute to mTOR activation in perilysosomal microdomains, leading to autophagic defects and β-cell failure due to lipotoxicity. This review delineates the antagonistic regulation of autophagic flux by mTOR and AMP-dependent protein kinase (AMPK) at the lysosomal membrane, and both of these molecules could be activated by perilysosomal calcium signaling. However, aberrant and persistent Ca2+ elevation upon lipotoxic stress increases mTOR activity and suppresses autophagy. Therefore, normalization of autophagy is an attractive therapeutic strategy for patients with β-cell failure and diabetes.
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Affiliation(s)
- Ha Thu Nguyen
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea
| | | | - Claes B Wollheim
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
- Department of Clinical Sciences, Lund University, Malmö, Sweden.
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea.
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5
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Alvim JM, Venturini G, Oliveira TGM, Seidman JG, Seidman CE, Krieger JE, Pereira AC. mTOR signaling inhibition decreases lysosome migration and impairs the success of Trypanosoma cruzi infection and replication in cardiomyocytes. Acta Trop 2023; 240:106845. [PMID: 36709791 DOI: 10.1016/j.actatropica.2023.106845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 01/27/2023]
Abstract
Chagas disease is caused by the parasite Trypanosoma cruzi (T. cruzi) and, among all the chronic manifestations of the disease, Chronic Chagas Cardiomyopathy (CCC) is the most severe outcome. Despite high burden and public health importance in Latin America, there is a gap in understanding the molecular mechanisms that results in CCC development. Previous studies showed that T. cruzi uses the host machinery for infection and replication, including the repurposing of the responses to intracellular infection such as mitochondrial activity, vacuolar membrane, and lysosomal activation in benefit of parasite infection and replication. One common signaling upstream to many responses to parasite infection is mTOR pathway, previous associated to several downstream cellular mechanisms including autophagy, mitophagy and lysosomal activation. Here, using human iPSC derived cardiomyocytes (hiPSCCM), we show the mTOR pathway is activated in hiPSCCM after T. cruzi infection, and the inhibition of mTOR with rapamycin reduced number of T. cruzi 48 h post infection (hpi). Rapamycin treatment also reduced lysosome migration from nuclei region to cell periphery resulting in less T. cruzi inside the parasitophorous vacuole (PV) in the first hour of infection. In addition, the number of parasites leaving the PV to the cytoplasm to replicate in later times of infection was also lower after rapamycin treatment. Altogether, our data suggest that host's mTOR activation concomitant with parasite infection modulates lysosome migration and that T. cruzi uses this mechanism to achieve infection and replication. Modulating this mechanism with rapamycin impaired the success of T. cruzi life cycle independent of mitophagy.
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Affiliation(s)
- Juliana M Alvim
- Heart Institute, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Laboratory of Genetics and Molecular Cardiology, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil
| | - Gabriela Venturini
- Heart Institute, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Laboratory of Genetics and Molecular Cardiology, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Department of Genetics, Harvard Medical School, United States.
| | - Theo G M Oliveira
- Heart Institute, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Laboratory of Genetics and Molecular Cardiology, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Fundação Pró-Sangue Hemocentro de São Paulo, Brazil
| | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, United States; Brigham and Women's Hospital, Harvard Medical School, United States; Howard Hughes Medical Institute (HHMI), United States
| | - José E Krieger
- Heart Institute, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Laboratory of Genetics and Molecular Cardiology, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil
| | - Alexandre C Pereira
- Heart Institute, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Laboratory of Genetics and Molecular Cardiology, Clinical Hospital, Faculty of Medicine, University of São Paulo, Brazil; Department of Genetics, Harvard Medical School, United States
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6
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New Insights into the Regulation of mTOR Signaling via Ca 2+-Binding Proteins. Int J Mol Sci 2023; 24:ijms24043923. [PMID: 36835331 PMCID: PMC9959742 DOI: 10.3390/ijms24043923] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Environmental factors are important regulators of cell growth and proliferation. Mechanistic target of rapamycin (mTOR) is a central kinase that maintains cellular homeostasis in response to a variety of extracellular and intracellular inputs. Dysregulation of mTOR signaling is associated with many diseases, including diabetes and cancer. Calcium ion (Ca2+) is important as a second messenger in various biological processes, and its intracellular concentration is tightly regulated. Although the involvement of Ca2+ mobilization in mTOR signaling has been reported, the detailed molecular mechanisms by which mTOR signaling is regulated are not fully understood. The link between Ca2+ homeostasis and mTOR activation in pathological hypertrophy has heightened the importance in understanding Ca2+-regulated mTOR signaling as a key mechanism of mTOR regulation. In this review, we introduce recent findings on the molecular mechanisms of regulation of mTOR signaling by Ca2+-binding proteins, particularly calmodulin (CaM).
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7
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Amemiya Y, Nakamura N, Ikeda N, Sugiyama R, Ishii C, Maki M, Shibata H, Takahara T. Amino Acid-Mediated Intracellular Ca 2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca 2+/Calmodulin. Int J Mol Sci 2021; 22:ijms22136897. [PMID: 34198993 PMCID: PMC8269083 DOI: 10.3390/ijms22136897] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 12/13/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a master growth regulator by controlling protein synthesis and autophagy in response to environmental cues. Amino acids, especially leucine and arginine, are known to be important activators of mTORC1 and to promote lysosomal translocation of mTORC1, where mTORC1 is thought to make contact with its activator Rheb GTPase. Although amino acids are believed to exclusively regulate lysosomal translocation of mTORC1 by Rag GTPases, how amino acids increase mTORC1 activity besides regulation of mTORC1 subcellular localization remains largely unclear. Here we report that amino acids also converge on regulation of the TSC2-Rheb GTPase axis via Ca2+/calmodulin (CaM). We showed that the amino acid-mediated increase of intracellular Ca2+ is important for mTORC1 activation and thereby contributes to the promotion of nascent protein synthesis. We found that Ca2+/CaM interacted with TSC2 at its GTPase activating protein (GAP) domain and that a CaM inhibitor reduced binding of CaM with TSC2. The inhibitory effect of a CaM inhibitor on mTORC1 activity was prevented by loss of TSC2 or by an active mutant of Rheb GTPase, suggesting that a CaM inhibitor acts through the TSC2-Rheb axis to inhibit mTORC1 activity. Taken together, in response to amino acids, Ca2+/CaM-mediated regulation of the TSC2-Rheb axis contributes to proper mTORC1 activation, in addition to the well-known lysosomal translocation of mTORC1 by Rag GTPases.
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8
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Takahara T, Amemiya Y, Sugiyama R, Maki M, Shibata H. Amino acid-dependent control of mTORC1 signaling: a variety of regulatory modes. J Biomed Sci 2020; 27:87. [PMID: 32799865 PMCID: PMC7429791 DOI: 10.1186/s12929-020-00679-2] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/30/2020] [Indexed: 01/10/2023] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is an essential regulator of cell growth and metabolism through the modulation of protein and lipid synthesis, lysosome biogenesis, and autophagy. The activity of mTORC1 is dynamically regulated by several environmental cues, including amino acid availability, growth factors, energy levels, and stresses, to coordinate cellular status with environmental conditions. Dysregulation of mTORC1 activity is closely associated with various diseases, including diabetes, cancer, and neurodegenerative disorders. The discovery of Rag GTPases has greatly expanded our understanding of the regulation of mTORC1 activity by amino acids, especially leucine and arginine. In addition to Rag GTPases, other factors that also contribute to the modulation of mTORC1 activity have been identified. In this review, we discuss the mechanisms of regulation of mTORC1 activity by particular amino acids.
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Affiliation(s)
- Terunao Takahara
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.
| | - Yuna Amemiya
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Risa Sugiyama
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Masatoshi Maki
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Hideki Shibata
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
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9
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TMBIM6/BI-1 contributes to cancer progression through assembly with mTORC2 and AKT activation. Nat Commun 2020; 11:4012. [PMID: 32782388 PMCID: PMC7419509 DOI: 10.1038/s41467-020-17802-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 07/16/2020] [Indexed: 01/09/2023] Open
Abstract
Transmembrane B cell lymphoma 2-associated X protein inhibitor motif-containing (TMBIM) 6, a Ca2+ channel-like protein, is highly up-regulated in several cancer types. Here, we show that TMBIM6 is closely associated with survival in patients with cervical, breast, lung, and prostate cancer. TMBIM6 deletion or knockdown suppresses primary tumor growth. Further, mTORC2 activation is up-regulated by TMBIM6 and stimulates glycolysis, protein synthesis, and the expression of lipid synthesis genes and glycosylated proteins. Moreover, ER-leaky Ca2+ from TMBIM6, a unique characteristic, is shown to affect mTORC2 assembly and its association with ribosomes. In addition, we identify that the BIA compound, a potentialTMBIM6 antagonist, prevents TMBIM6 binding to mTORC2, decreases mTORC2 activity, and also regulates TMBIM6-leaky Ca2+, further suppressing tumor formation and progression in cancer xenograft models. This previously unknown signaling cascade in which mTORC2 activity is enhanced via the interaction with TMBIM6 provides potential therapeutic targets for various malignancies. TMBIM6, a member of the transmembrane BI-1 motif-containing family of proteins, is overexpressed in many cancer types. Here, the authors show that TMBIM6 regulates AKT activation through mTORC2 assembly and ribosome association and identify an antagonist of TMBIM6 with anti-tumor properties.
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10
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Dalle S, Hiroux C, Poffé C, Ramaekers M, Deldicque L, Koppo K. Cardiotoxin-induced skeletal muscle injury elicits profound changes in anabolic and stress signaling, and muscle fiber type composition. J Muscle Res Cell Motil 2020; 41:375-387. [PMID: 32621158 DOI: 10.1007/s10974-020-09584-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/12/2020] [Indexed: 12/20/2022]
Abstract
To improve muscle healing upon injury, it is of importance to understand the interplay of key signaling pathways during muscle regeneration. To study this, mice were injected with cardiotoxin (CTX) or PBS in the Tibialis Anterior muscle and were sacrificed 2, 5 and 12 days upon injection. The time points represent different phases of the regeneration process, i.e. destruction, repair and remodeling, respectively. Two days upon CTX-injection, p-mTORC1 signaling and stress markers such as BiP and p-ERK1/2 were upregulated. Phospho-ERK1/2 and p-mTORC1 peaked at d5, while BiP expression decreased towards PBS levels. Phospho-FOXO decreased 2 and 5 days following CTX-injection, indicative of an increase in catabolic signaling. Furthermore, CTX-injection induced a shift in the fiber type composition, characterized by an initial loss in type IIa fibers at d2 and at d5. At d5, new type IIb fibers appeared, whereas type IIa fibers were recovered at d12. To conclude, CTX-injection severely affected key modulators of muscle metabolism and histology. These data provide useful information for the development of strategies that aim to improve muscle molecular signaling and thereby recovery.
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Affiliation(s)
- Sebastiaan Dalle
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Tervuursevest 101, 3001, Louvain, Belgium
| | - Charlotte Hiroux
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Tervuursevest 101, 3001, Louvain, Belgium
| | - Chiel Poffé
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Tervuursevest 101, 3001, Louvain, Belgium
| | - Monique Ramaekers
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Tervuursevest 101, 3001, Louvain, Belgium
| | - Louise Deldicque
- Institute of Neuroscience, Université Catholique de Louvain, Place Pierre de Coubertin 1, 1348, Louvain-la-Neuve, Belgium
| | - Katrien Koppo
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Tervuursevest 101, 3001, Louvain, Belgium.
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11
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Bonnefond ML, Florent R, Lenoir S, Lambert B, Abeilard E, Giffard F, Louis MH, Elie N, Briand M, Vivien D, Poulain L, Gauduchon P, N'Diaye M. Inhibition of store-operated channels by carboxyamidotriazole sensitizes ovarian carcinoma cells to anti-Bclx L strategies through Mcl-1 down-regulation. Oncotarget 2018; 9:33896-33911. [PMID: 30338034 PMCID: PMC6188062 DOI: 10.18632/oncotarget.26084] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 08/04/2018] [Indexed: 12/22/2022] Open
Abstract
The anti-apoptotic proteins Bcl-xL and Mcl-1 have been identified to play a pivotal role in apoptosis resistance in ovarian cancer and constitute key targets for innovative therapeutic strategies. Although BH3-mimetics (i.e. ABT-737) potently inhibit Bcl-xL activity, targeting Mcl-1 remains a hurdle to the success of these strategies. Calcium signaling is profoundly remodeled during carcinogenesis and was reported to activate the signaling pathway controlling Mcl-1 expression. In this context, we investigated the effect of carboxyamidotriazole (CAI), a calcium channel inhibitor used in clinical trials, on Mcl-1 expression. CAI had an anti-proliferative effect on ovarian carcinoma cell lines and strongly down-regulated Mcl-1 expression. It inhibited store-operated calcium entry (SOCE) and Mcl-1 translation through mTORC1 deactivation. Moreover, it sensitized ovarian carcinoma cells to anti-Bcl-xL strategies as their combination elicited massive apoptosis. Its effect on mTORC1 and Mcl-1 was mimicked by the potent SOCE inhibitor, YM58483, which also triggered apoptosis when combined with ABT-737. As a whole, this study suggests that CAI sensitizes to anti-Bcl-xL strategies via its action on Mcl-1 translation and that modulation of SOCE could extend the therapeutic arsenal for treatment of ovarian carcinoma.
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Affiliation(s)
- Marie-Laure Bonnefond
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Romane Florent
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Sophie Lenoir
- Normandie University, UNICAEN, INSERM UMR-S 1237, Physiopathologie et Imagerie des Troubles Neurologiques (PhIND), tPA and Neurovascular Disorders Team, Caen, France
| | - Bernard Lambert
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
- Délégation Régionale de Normandie, CNRS, Caen, France
| | - Edwige Abeilard
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Florence Giffard
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Marie-Hélène Louis
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Nicolas Elie
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- Normandie University, UNICAEN, Centre de Microscopie Appliqué à la Biologie, CMabio3, Structure Fédérative 4206 ICORE, Caen, France
| | - Mélanie Briand
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
- Centre de Ressources Biologiques, OvaRessources, François Baclesse Cancer Center, Caen, France
| | - Denis Vivien
- Normandie University, UNICAEN, INSERM UMR-S 1237, Physiopathologie et Imagerie des Troubles Neurologiques (PhIND), tPA and Neurovascular Disorders Team, Caen, France
| | - Laurent Poulain
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Pascal Gauduchon
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
| | - Monique N'Diaye
- Normandie University, UNICAEN, INSERM U1086 ANTICIPE, Interdisciplinary Research Unit for Cancer Prevention and Treatment, BioTICLA Axis, Biology and Innovative Therapeutics for Ovarian Cancers, Caen, France
- UNICANCER, François Baclesse Cancer Center, BioTICLA Laboratory, Caen, France
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12
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Li RJ, Xu J, Fu C, Zhang J, Zheng YG, Jia H, Liu JO. Regulation of mTORC1 by lysosomal calcium and calmodulin. eLife 2016; 5. [PMID: 27787197 PMCID: PMC5106211 DOI: 10.7554/elife.19360] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 10/26/2016] [Indexed: 11/13/2022] Open
Abstract
Blockade of lysosomal calcium release due to lysosomal lipid accumulation has been shown to inhibit mTORC1 signaling. However, the mechanism by which lysosomal calcium regulates mTORC1 has remained undefined. Herein we report that proper lysosomal calcium release through the calcium channel TRPML1 is required for mTORC1 activation. TRPML1 depletion inhibits mTORC1 activity, while overexpression or pharmacologic activation of TRPML1 has the opposite effect. Lysosomal calcium activates mTORC1 by inducing association of calmodulin (CaM) with mTOR. Blocking the interaction between mTOR and CaM by antagonists of CaM significantly inhibits mTORC1 activity. Moreover, CaM is capable of stimulating the kinase activity of mTORC1 in a calcium-dependent manner in vitro. These results reveal that mTOR is a new type of CaM-dependent kinase, and TRPML1, lysosomal calcium and CaM play essential regulatory roles in the mTORC1 signaling pathway.
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Affiliation(s)
- Ruo-Jing Li
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, United States.,The SJ Yan and HJ Mao Laboratory of Chemical Biology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Jing Xu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, United States.,The SJ Yan and HJ Mao Laboratory of Chemical Biology, Johns Hopkins University School of Medicine, Baltimore, United States.,Eli Lilly and Company, Indianapolis, United States
| | - Chenglai Fu
- The Solomon H Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Jing Zhang
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, United States
| | - Yujun George Zheng
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, United States
| | - Hao Jia
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Jun O Liu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, United States.,The SJ Yan and HJ Mao Laboratory of Chemical Biology, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, United States
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13
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Goodman CA, Hornberger TA, Robling AG. Bone and skeletal muscle: Key players in mechanotransduction and potential overlapping mechanisms. Bone 2015; 80:24-36. [PMID: 26453495 PMCID: PMC4600534 DOI: 10.1016/j.bone.2015.04.014] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 03/18/2015] [Accepted: 04/07/2015] [Indexed: 12/16/2022]
Abstract
The development and maintenance of skeletal muscle and bone mass is critical for movement, health and issues associated with the quality of life. Skeletal muscle and bone mass are regulated by a variety of factors that include changes in mechanical loading. Moreover, bone mass is, in large part, regulated by muscle-derived mechanical forces and thus by changes in muscle mass/strength. A thorough understanding of the cellular mechanism(s) responsible for mechanotransduction in bone and skeletal muscle is essential for the development of effective exercise and pharmaceutical strategies aimed at increasing, and/or preventing the loss of, mass in these tissues. Thus, in this review we will attempt to summarize the current evidence for the major molecular mechanisms involved in mechanotransduction in skeletal muscle and bone. By examining the differences and similarities in mechanotransduction between these two tissues, it is hoped that this review will stimulate new insights and ideas for future research and promote collaboration between bone and muscle biologists.(1).
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Affiliation(s)
- Craig A Goodman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA; Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Australia; Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, VIC, Australia.
| | - Troy A Hornberger
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Roudebush Veterans Affairs Medical Center, Indianapolis, IN 46202, USA; Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN 46202, USA
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14
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Ca(2+) permeation and/or binding to CaV1.1 fine-tunes skeletal muscle Ca(2+) signaling to sustain muscle function. Skelet Muscle 2015; 5:4. [PMID: 25717360 PMCID: PMC4340672 DOI: 10.1186/s13395-014-0027-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/11/2014] [Indexed: 11/13/2022] Open
Abstract
Background Ca2+ influx through CaV1.1 is not required for skeletal muscle excitation-contraction coupling, but whether Ca2+ permeation through CaV1.1 during sustained muscle activity plays a functional role in mammalian skeletal muscle has not been assessed. Methods We generated a mouse with a Ca2+ binding and/or permeation defect in the voltage-dependent Ca2+ channel, CaV1.1, and used Ca2+ imaging, western blotting, immunohistochemistry, proximity ligation assays, SUnSET analysis of protein synthesis, and Ca2+ imaging techniques to define pathways modulated by Ca2+ binding and/or permeation of CaV1.1. We also assessed fiber type distributions, cross-sectional area, and force frequency and fatigue in isolated muscles. Results Using mice with a pore mutation in CaV1.1 required for Ca2+ binding and/or permeation (E1014K, EK), we demonstrate that CaV1.1 opening is coupled to CaMKII activation and refilling of sarcoplasmic reticulum Ca2+ stores during sustained activity. Decreases in these Ca2+-dependent enzyme activities alter downstream signaling pathways (Ras/Erk/mTORC1) that lead to decreased muscle protein synthesis. The physiological consequences of the permeation and/or Ca2+ binding defect in CaV1.1 are increased fatigue, decreased fiber size, and increased Type IIb fibers. Conclusions While not essential for excitation-contraction coupling, Ca2+ binding and/or permeation via the CaV1.1 pore plays an important modulatory role in muscle performance. Electronic supplementary material The online version of this article (doi:10.1186/s13395-014-0027-1) contains supplementary material, which is available to authorized users.
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15
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Wang Z, Liu S, Kakizaki M, Hirose Y, Ishikawa Y, Funato H, Yanagisawa M, Yu Y, Liu Q. Orexin/hypocretin activates mTOR complex 1 (mTORC1) via an Erk/Akt-independent and calcium-stimulated lysosome v-ATPase pathway. J Biol Chem 2014; 289:31950-31959. [PMID: 25278019 PMCID: PMC4231673 DOI: 10.1074/jbc.m114.600015] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 09/30/2014] [Indexed: 02/05/2023] Open
Abstract
The lack of the neuropeptide orexin, also known as hypocretin, results in narcolepsy, a chronic sleep disorder characterized by frequent sleep/cataplexy attacks and rapid eye movement sleep abnormalities. However, the downstream pathways of orexin signaling are not clearly understood. Here, we show that orexin activates the mTOR pathway, a central regulator of cell growth and metabolism, in the mouse brain and multiple recombinant cell lines that express the G protein-coupled receptors (GPCRs), orexin 1 receptor (OX1R) or orexin 2 receptor (OX2R). This orexin/GPCR-stimulated mTOR activation is sensitive to rapamycin, an inhibitor of mTOR complex 1 (mTORC1) but is independent of two well known mTORC1 activators, Erk and Akt. Rather, our studies indicate that orexin activates mTORC1 via extracellular calcium influx and the lysosome pathway involving v-ATPase and Rag GTPases. Moreover, a cytoplasmic calcium transient is sufficient to mimic orexin/GPCR signaling to mTORC1 activation in a v-ATPase-dependent manner. Together, our studies suggest that the mTORC1 pathway functions downstream of orexin/GPCR signaling, which plays a crucial role in many physiological and metabolic processes.
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Affiliation(s)
- Zhiqiang Wang
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Shimeng Liu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390,; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Miyo Kakizaki
- International Institute of Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki 305-8575, Japan, and
| | - Yuuki Hirose
- International Institute of Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki 305-8575, Japan, and
| | - Yukiko Ishikawa
- International Institute of Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki 305-8575, Japan, and
| | - Hiromasa Funato
- International Institute of Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki 305-8575, Japan, and; Department of Anatomy, Toho University School of Medicine, Tokyo 143-8540, Japan
| | - Masashi Yanagisawa
- International Institute of Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki 305-8575, Japan, and
| | - Yonghao Yu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390,.
| | - Qinghua Liu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390,; International Institute of Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki 305-8575, Japan, and.
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16
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Lee CS, Georgiou DK, Dagnino-Acosta A, Xu J, Ismailov II, Knoblauch M, Monroe TO, Ji R, Hanna AD, Joshi AD, Long C, Oakes J, Tran T, Corona BT, Lorca S, Ingalls CP, Narkar VA, Lanner JT, Bayle JH, Durham WJ, Hamilton SL. Ligands for FKBP12 increase Ca2+ influx and protein synthesis to improve skeletal muscle function. J Biol Chem 2014; 289:25556-70. [PMID: 25053409 DOI: 10.1074/jbc.m114.586289] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Rapamycin at high doses (2-10 mg/kg body weight) inhibits mammalian target of rapamycin complex 1 (mTORC1) and protein synthesis in mice. In contrast, low doses of rapamycin (10 μg/kg) increase mTORC1 activity and protein synthesis in skeletal muscle. Similar changes are found with SLF (synthetic ligand for FKBP12, which does not inhibit mTORC1) and in mice with a skeletal muscle-specific FKBP12 deficiency. These interventions also increase Ca(2+) influx to enhance refilling of sarcoplasmic reticulum Ca(2+) stores, slow muscle fatigue, and increase running endurance without negatively impacting cardiac function. FKBP12 deficiency or longer treatments with low dose rapamycin or SLF increase the percentage of type I fibers, further adding to fatigue resistance. We demonstrate that FKBP12 and its ligands impact multiple aspects of muscle function.
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Affiliation(s)
- Chang Seok Lee
- From the Baylor College of Medicine, Houston, Texas 77030
| | | | | | - Jianjun Xu
- From the Baylor College of Medicine, Houston, Texas 77030
| | | | - Mark Knoblauch
- From the Baylor College of Medicine, Houston, Texas 77030
| | | | - RuiRui Ji
- From the Baylor College of Medicine, Houston, Texas 77030
| | - Amy D Hanna
- From the Baylor College of Medicine, Houston, Texas 77030
| | - Aditya D Joshi
- From the Baylor College of Medicine, Houston, Texas 77030
| | - Cheng Long
- From the Baylor College of Medicine, Houston, Texas 77030
| | - Joshua Oakes
- From the Baylor College of Medicine, Houston, Texas 77030
| | - Ted Tran
- From the Baylor College of Medicine, Houston, Texas 77030
| | - Benjamin T Corona
- the Muscle Biology Laboratory, Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia 30302
| | - Sabina Lorca
- the Center for Metabolic and Degenerative Disease, University of Texas Health Science Center, Houston, Texas 77030, and
| | - Christopher P Ingalls
- the Muscle Biology Laboratory, Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia 30302
| | - Vihang A Narkar
- the Center for Metabolic and Degenerative Disease, University of Texas Health Science Center, Houston, Texas 77030, and
| | | | - J Henri Bayle
- From the Baylor College of Medicine, Houston, Texas 77030
| | - William J Durham
- the Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555-1041
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17
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The role of mTORC1 in regulating protein synthesis and skeletal muscle mass in response to various mechanical stimuli. Rev Physiol Biochem Pharmacol 2013; 166:43-95. [PMID: 24442322 DOI: 10.1007/112_2013_17] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Skeletal muscle plays a fundamental role in mobility, disease prevention, and quality of life. Skeletal muscle mass is, in part, determined by the rates of protein synthesis, and mechanical loading is a major regulator of protein synthesis and skeletal muscle mass. The mammalian/mechanistic target of rapamycin (mTOR), found in the multi-protein complex, mTORC1, is proposed to play an essential role in the regulation of protein synthesis and skeletal muscle mass. The purpose of this review is to examine the function of mTORC1 in relation to protein synthesis and cell growth, the current evidence from rodent and human studies for the activation of mTORC1 signaling by different types of mechanical stimuli, whether mTORC1 signaling is necessary for changes in protein synthesis and skeletal muscle mass that occur in response to different types of mechanical stimuli, and the proposed molecular signaling mechanisms that may be responsible for the mechanical activation of mTORC1 signaling.
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18
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Novel role for SHP-2 in nutrient-responsive control of S6 kinase 1 signaling. Mol Cell Biol 2012; 33:293-306. [PMID: 23129808 DOI: 10.1128/mcb.01285-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Amino acids are required for the activation of the mammalian target of rapamycin complex 1 (mTORC1), which plays a critical role in cell growth, proliferation, and metabolism. The branched-chain amino acid leucine is an essential nutrient that stimulates mTORC1 to promote protein synthesis by activating p70 S6 kinase 1 (S6K1). Here we show that the protein tyrosine phosphatase SHP-2 is required for leucine-induced activation of S6K1 in skeletal myoblasts. In response to leucine, S6K1 activation is inhibited in myoblasts either lacking SHP-2 expression or overexpressing a catalytically inactive mutant of SHP-2. Activation of S6K1 by leucine requires the mobilization of intracellular calcium (Ca(2+)), which we show is mediated by SHP-2 in an inositol-1,4,5-trisphosphate-dependent manner. Ectopic Ca(2+) mobilization rescued the S6K1 activation defect in SHP-2-deficient myoblasts. SHP-2 was identified to act upstream of phospholipase C β4, linking it to the generation of nutrient-induced Ca(2+) release and S6K1 phosphorylation. Consistent with these results, SHP-2-deficient myoblasts exhibited impaired leucine sensing, leading to defective autophagy and reduced myoblast size. These data define a new role for SHP-2 as a nutrient-sensing regulator in skeletal myoblasts that is required for the activation of S6K1.
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19
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Susceptibility test of two Ca(2+)-ATPase conformers to denaturants and polyols to outline their structural difference. J Membr Biol 2012; 246:141-9. [PMID: 23124945 DOI: 10.1007/s00232-012-9513-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 10/15/2012] [Indexed: 10/27/2022]
Abstract
To determine the effect of denaturants [guanidine hydrochloride (GdnHCl) and urea] and polyols [with various molecular masses (62.1-600)] on calcium binding at the two hypothesized conformers (A and B forms) of the chemically equivalent sarcoplasmic reticulum Ca(2+)-ATPase, which bind two calcium ions in different manners, we examined the effect of these reagents on the calcium dependence of ATP-supported phosphorylation of the ATPase molecules and of their calcium-activated, acetyl phosphatate hydrolytic activity. (1) GdnHCl (~0.05 M) and urea (~0.5 M) increased the apparent calcium affinity (K (0.5)) of 2-6 μM of noncooperative binding [Hill coefficient (n (H)) ~ 1] of the A form to 10-40 μM. (2) The employed polyols transformed the binding of the A form into cooperative binding (n (H) ~ 2), accompanying the approach of its K (0.5) value to that (K (0.5) = 0.04-0.2 μM) of the cooperative binding (n (H) ~ 2) of the B form; the transition concentration (0.025-2 M) of the polyols, above which such transformation occurs, was in inverse relation to their molecular mass. (3) The binding of the B form was resistant to these denaturants and polyols. Based on these data, a structural model of the two forms, calcium-binding domains of which are loosely and compactly folded, is presented.
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20
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Khan MT, Joseph SK. Role of inositol trisphosphate receptors in autophagy in DT40 cells. J Biol Chem 2010; 285:16912-20. [PMID: 20308071 DOI: 10.1074/jbc.m110.114207] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Previous studies have shown that small interfering RNA knockdown and pharmacological inhibition of inositol 1,4,5-trisphosphate receptors (IP(3)Rs) stimulate autophagy. We have investigated autophagy in chicken DT40 cell lines containing targeted deletions of all three IP(3)R isoforms (triple knock-out (TKO) cells). Using gel shifts of microtubule-associated protein 1 light chain 3 as a marker of autophagy, we find that TKO cells have enhanced basal autophagic flux even under nutrient-replete conditions. Stable DT40 cell lines derived from TKO cells containing the functionally inactive D2550A IP(3)R mutant did not suppress autophagy in the same manner as wild-type receptors. This suggests that the channel function of the receptor is important in its regulatory role in autophagy. There were no marked differences in the phosphorylation state of AMP-activated protein kinase, Akt, or mammalian target of rapamycin between wild-type and TKO cells. The amount of immunoprecipitated complexes of Bcl-2-Beclin-1 and Beclin-1-Vps34 were also not different between the two cell lines. The major difference noted was a substantially decreased mTORC1 kinase activity in TKO cells based on decreased phosphorylation of S6 kinase and 4E-BP1. The discharge of intracellular stores with thapsigargin stimulated mTORC1 activity (measured as S6 kinase phosphorylation) to a greater extent in wild-type than in TKO cells. We suggest that basal autophagic flux may be negatively regulated by IP(3)R-dependent Ca(2+) signals acting to maintain an elevated mTORC1 activity in wild-type cells and that Ca(2+) regulation of this enzyme is defective in TKO cells. The protective effect of a higher autophagic flux in cells lacking IP(3)Rs may play a role in the delayed apoptotic response observed in these cells.
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Affiliation(s)
- M Tariq Khan
- Department of Pathology and Cell Biology, Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania 19107, USA
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21
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Choi JH, Yang YR, Lee SK, Kim SH, Kim YH, Cha JY, Oh SW, Ha JR, Ryu SH, Suh PG. Potential Inhibition of PDK1/Akt Signaling by Phenothiazines Suppresses Cancer Cell Proliferation and Survival. Ann N Y Acad Sci 2008; 1138:393-403. [DOI: 10.1196/annals.1414.041] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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22
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Dewar BJ, Gardner OS, Chen CS, Earp HS, Samet JM, Graves LM. Capacitative Calcium Entry Contributes to the Differential Transactivation of the Epidermal Growth Factor Receptor in Response to Thiazolidinediones. Mol Pharmacol 2007; 72:1146-56. [PMID: 17686966 DOI: 10.1124/mol.107.037549] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Thiazolidinediones (TZDs) are synthetic ligands for the peroxisome proliferator-activated receptor gamma (PPARgamma) but also elicit PPARgamma-independent effects, most notably activation of mitogen-activated protein kinases (MAPKs). Ciglitazone rapidly activates extracellular signal-regulated kinase (Erk) MAPK, an event requiring c-Src kinase-dependent epidermal growth factor receptor (EGFR) transactivation, whereas troglitazone only weakly activates Erk and does not induce EGFR transactivation; the mechanism underlying this difference remains unclear. In this study, both ciglitazone and troglitazone increased Src activation. Similar effects were observed with Delta2-derivatives of each TZD, compounds that bind PPARgamma but do not lead to its activation, further indicating a PPARgamma-independent mechanism. Neither EGFR kinase nor Pyk2 inhibition prevented Src activation; however, inhibition of Src kinase activity prevented Pyk2 activation. Intracellular calcium chelation blocks TZD-induced Pyk2 activation; here, Src activation by both TZDs and ciglitazone-induced EGFR transactivation were prevented by calcium chelation. Accordingly, both TZDs increased calcium concentrations from intracellular stores; however, only ciglitazone produced a secondary calcium influx in the presence of extracellular calcium. Removal of extracellular calcium or inhibition of capacitative calcium entry by 2-APB prevented ciglitazone-induced EGFR transactivation and Erk activation but did not affect upstream kinase signaling pathways. These results demonstrate that upstream kinases (i.e., Src and Pyk2) are required but not sufficient for EGFR transactivation by TZDs. Moreover, influx of extracellular calcium through capacitative calcium entry may be an unrecognized component that provides a mechanism for the differential induction of EGFR transactivation by these compounds.
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Affiliation(s)
- Brian J Dewar
- Curriculum in Toxicology , University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365, USA
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23
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Wu EHT, Wu KKH, Wong YH. Tuberin: a stimulus-regulated tumor suppressor protein controlled by a diverse array of receptor tyrosine kinases and G protein-coupled receptors. Neurosignals 2007; 15:217-27. [PMID: 17389815 DOI: 10.1159/000101333] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Accepted: 02/09/2007] [Indexed: 02/02/2023] Open
Abstract
Tuberin, a tumor suppressor protein, is involved in various cellular functions including survival, proliferation, and growth. It has emerged as an important effector regulated by receptor tyrosine kinases (RTKs) and G protein-coupled receptors (GPCRs). Regulation of tuberin by RTKs and GPCRs is highly complex and dependent on the type of receptors and their associated signaling molecules. Apart from Akt, the first kinase recognized to phosphorylate and inactivate tuberin upon growth factor stimulation, an increasing number of kinases upstream of tuberin have been identified. Furthermore, recruitment of different scaffolding adaptor components to the activated receptors appears to play an important role in the regulation of tuberin activity. More recently, the differential regulation of tuberin by various G protein family members have also been intensively studied, it appears that G proteins can both facilitate (e.g., G(i/o)) as well as inhibit (e.g., G(q)) tuberin phosphorylation. In the present review, we attempt to summarize our emerging understandings of the roles of RTKs, GPCRs, and their cross-talk on the regulation of tuberin.
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Affiliation(s)
- Eddy H T Wu
- Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, SAR, China
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24
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Rhoads JM, Corl BA, Harrell R, Niu X, Gatlin L, Phillips O, Blikslager A, Moeser A, Wu G, Odle J. Intestinal ribosomal p70(S6K) signaling is increased in piglet rotavirus enteritis. Am J Physiol Gastrointest Liver Physiol 2007; 292:G913-22. [PMID: 17138969 DOI: 10.1152/ajpgi.00468.2006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recent identification of the mammalian target of rapamycin (mTOR) pathway as an amino acid-sensing mechanism that regulates protein synthesis led us to investigate its role in rotavirus diarrhea. We hypothesized that malnutrition would reduce the jejunal protein synthetic rate and mTOR signaling via its target, ribosomal p70 S6 kinase (p70(S6K)). Newborn piglets were artificially fed from birth and infected with porcine rotavirus on day 5 of life. Study groups included infected (fully fed and 50% protein calorie malnourished) and noninfected fully fed controls. Initially, in "worst-case scenario studies," malnourished infected piglets were killed on days 1, 3, 5, and 11 postinoculation, and jejunal samples were compared with controls to determine the time course of injury and p70(S6K) activation. Using a 2 x 2 factorial design, we subsequently determined if infection and/or malnutrition affected mTOR activation on day 3. Western blot analysis and immunohistochemistry were used to measure total and phosphorylated p70(S6K); [(3)H]phenylalanine incorporation was used to measure protein synthesis; and lactase specific activity and villus-crypt dimensions were used to quantify injury. At the peak of diarrhea, the in vitro jejunal protein synthetic rate increased twofold (compared with the rate in the uninfected pig jejunum), concomitant with increased jejunal p70(S6K) phosphorylation (4-fold) and an increased p70(S6K) level (3-fold, P < 0.05). Malnutrition did not alter the magnitude of p70(S6K) activation. Immunolocalization revealed that infection produced a major induction of cytoplasmic p70(S6K) and nuclear phospho-p70(S6K), mainly in the crypt. A downregulation of semitendinosus muscle p70(S6K) phosphorylation was seen at days 1-3 postinoculation. In conclusion, intestinal activation of p70(S6K) was not inhibited by malnutrition but was strongly activated during an active state of mucosal regeneration.
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Affiliation(s)
- J Marc Rhoads
- Department of Pediatrics, Ochsner Clinic Foundation and Ochsner Children's Research Institute, New Orleans, Louisiana, USA.
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25
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Krishna SB, Alfonso LF, Thekkumkara TJ, Abbruscato TJ, Bhat GJ. Angiotensin II induces phosphorylation of glucose-regulated protein-75 in WB rat liver cells. Arch Biochem Biophys 2006; 457:16-28. [PMID: 17109810 PMCID: PMC2577571 DOI: 10.1016/j.abb.2006.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 10/06/2006] [Accepted: 10/12/2006] [Indexed: 01/19/2023]
Abstract
Studies in vascular smooth muscle cells suggest that, angiotensin II (Ang II)-mediated cellular response requires transactivation of epidermal growth factor receptor (EGF-R), and involves tyrosine phosphorylation of caveolin-1. Here we demonstrate that, exposure of WB rat liver cells to Ang II does not cause transactivation of EGF-R, but did rapidly activate p42/p44 mitogen-activated protein (MAP) kinases suggesting that it activates MAP kinases independent of EGF-R transactivation. We observed that the phospho-specific anti-caveolin-1 antibody detected a tyrosine phosphorylated, 75kDa protein in Ang II-treated cells which we identified as glucose regulated protein-75 (GRP-75). Phosphoamino acid analysis showed that Ang II induced its phosphorylation at tyrosine, serine and threonine residues and was localized to the cytoplasm. The ability of Ang-II to induce GRP-75 phosphorylation suggests that it may play a role in the protection of cytoplasmic proteins from the damaging effect of oxidative stress known to be produced during Ang-II induced signaling.
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Affiliation(s)
| | | | | | | | - G. Jayarama Bhat
- * To whom correspondence should be addressed. G. Jayarama Bhat, Ph.D., Associate Professor, Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, 1300 Coulter Drive, Amarillo, TX 79106, Tel: (806) 356-4015 ext 249, Fax: (806) 356-4034, E-mail:
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26
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Abstract
An early signaling event activated by amino acids and growth factors in many cell types is the phosphorylation of the mammalian target of rapamycin (mTOR; FRAP), which is functionally linked to ribosomal protein s6 kinase (p70(s6k)), a kinase that plays a critical regulatory role in the translation of mRNAs and protein synthesis. We previously showed that intestinal cell migration, the initial event in epithelial restitution, is enhanced by l-arginine (ARG). In this study, we used amino acids as prototypic activators of mTOR and ARG, IGF-1, or serum as recognized stimulators of intestinal cell migration. We found that 1) protein synthesis is required for intestinal cell migration, 2) mTOR/p70(s6k) pathway inhibitors (rapamycin, wortmannin, and intracellular Ca(2+) chelation) inhibit cell migration, 3) ARG activates migration and mTOR/p70(s6k) (but not ERK-2) in migrating enterocytes, and 4) immunocytochemistry reveals abundant p70(s6k) staining in cytoplasm, whereas phospho-p70(s6k) is virtually all intranuclear in resting cells but redistributes to the periphery on activation by ARG. We conclude that mTOR/p70(s6k) signaling is essential to intestinal cell migration, is activated by ARG, involves both nuclear and cytoplasmic events, and may play a role in intestinal repair.
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Affiliation(s)
- J Marc Rhoads
- Div. of Gastroenterology, Dept. of Pediatrics, Univ. of Texas Medical School at Houston, 6431 Fannin St., MSB 7.137, Houston, TX 77030, USA.
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Kwintkiewicz J, Spaczynski RZ, Foyouzi N, Pehlivan T, Duleba AJ. Insulin and oxidative stress modulate proliferation of rat ovarian theca-interstitial cells through diverse signal transduction pathways. Biol Reprod 2006; 74:1034-40. [PMID: 16481589 DOI: 10.1095/biolreprod.105.049908] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Insulin and moderate oxidative stress stimulate proliferation of ovarian theca-interstitial cells. The effects of these agents on selected signal transduction pathways were examined. PD98059 (inhibitor of MAP2K1, also known as MEK-1, upstream of extracellular signal-regulated protein kinases MAPK3/1, also known as ERK1/2), wortmannin (inhibitor of PIK3C2A, also known as PI3K), and rapamycin (inhibitor of FRAP1, also known as mTOR, upstream of RPS6KB1) each significantly decreased insulin and oxidative stress-induced proliferation of theca-interstitial cells. The greatest inhibition was observed in the presence of rapamycin; this effect occurred without a significant change in cell viability. Phosphorylation of AKT was stimulated by insulin only, while phosphorylation of MAPK3/1 and RPS6KB1 was increased by insulin and oxidative stress. Insulin-induced and oxidative stress-induced phosphorylation of RPS6KB1 was partly inhibited by wortmannin and partly by PD98059; the greatest inhibition was observed in the presence of a combination of wortmannin plus PD98059. Effects of insulin and oxidative stress on phosphorylation of RPS6KB1 were confirmed by kinase activity assays. These findings indicate that actions of insulin and oxidative stress converge on MAPK3/1 and RPS6KB1. Furthermore, we speculate that activation of RPS6KB1 may be in part induced via the MAPK3/1 pathway.
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Affiliation(s)
- Jakub Kwintkiewicz
- Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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28
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Sarbassov DD, Sabatini DM. Redox Regulation of the Nutrient-sensitive Raptor-mTOR Pathway and Complex. J Biol Chem 2005; 280:39505-9. [PMID: 16183647 DOI: 10.1074/jbc.m506096200] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The raptor-mTOR protein complex is a key component of a nutrient-sensitive signaling pathway that regulates cell size by controlling the accumulation of cellular mass. How nutrients regulate signaling through the raptor-mTOR complex is not well known. Here we show that a redox-sensitive mechanism regulates the phosphorylation of the raptor-mTOR effector S6K1, the interaction between raptor and mTOR, and the kinase activity of the raptor-mTOR complex. In cells treated with the oxidizing agents diamide or phenylarsine oxide, S6K1 phosphorylation increased and became insensitive to nutrient deprivation. Conversely, the reducing reagent BAL (British anti-Lewisite, also known as 2,3-dimercapto-1-propanol) inhibits S6K1 phosphorylation and stabilizes the interaction of mTOR and raptor to mimic the state of the complex under nutrient-deprived conditions. Our findings suggest that a redox-based signaling mechanism may participate in regulating the nutrient-sensitive raptor-mTOR complex and pathway.
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Affiliation(s)
- Dos D Sarbassov
- Department of Biology, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
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29
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Hirotani S, Higuchi Y, Nishida K, Nakayama H, Yamaguchi O, Hikoso S, Takeda T, Kashiwase K, Watanabe T, Asahi M, Taniike M, Tsujimoto I, Matsumura Y, Sasaki T, Hori M, Otsu K. Ca(2+)-sensitive tyrosine kinase Pyk2/CAK beta-dependent signaling is essential for G-protein-coupled receptor agonist-induced hypertrophy. J Mol Cell Cardiol 2005; 36:799-807. [PMID: 15158121 DOI: 10.1016/j.yjmcc.2004.03.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Revised: 02/23/2004] [Accepted: 03/01/2004] [Indexed: 11/19/2022]
Abstract
G-protein-coupled receptor agonists including endothelin-1 (ET-1) and phenylephrine (PE) induce hypertrophy in neonatal ventricular cardiomyocytes. Others and we previously reported that Rac1 signaling pathway plays an important role in this agonist-induced cardiomyocyte hypertrophy. In this study reported here, we found that a Ca(2+)-sensitive non-receptor tyrosine kinase, proline-rich tyrosine kinase 2 (Pyk2)/cell adhesion kinase beta (CAKbeta), is involved in ET-1- and PE-induced cardiomyocyte hypertrophy medicated through Rac1 activation. ET-1, PE or the Ca(2+) inophore, ionomycin, stimulated a rapid increase in tyrosine phosphorylation of Pyk2. The tyrosine phosphorylation of Pyk2 was suppressed by the Ca(2+) chelator, BAPTA. ET-1- or PE-induced increases in [(3)H]-leucine incorporation and expression of atrial natriuretic factor and the enhancement of sarcomere organization. Infection of cardiomyocytes with an adenovirus expressing a mutant Pyk2 which lacked its kinase domain or its ability to bind to c-Src, eliminated ET-1- and PE-induced hypertrophic responses. Inhibition of Pyk2 activation also suppressed Rac1 activation and reactive oxygen species (ROS) production. These findings suggest that the signal transduction pathway leading to hypertrophy involves Ca(2+)-induced Pyk2 activation followed by Rac1-dependent ROS production.
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Affiliation(s)
- Shinichi Hirotani
- Department of Internal Medicine and Therapeutics, Graduate School of Medicine, Osaka University, Box A8, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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Bae GU, Kim YK, Kwon HK, Park JW, Lee EK, Paek SJ, Choi WS, Jung ID, Lee HY, Cho EJ, Lee HW, Han JW. Hydrogen peroxide mediates Rac1 activation of S6K1. Exp Cell Res 2004; 300:476-84. [PMID: 15475011 DOI: 10.1016/j.yexcr.2004.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2004] [Revised: 07/19/2004] [Indexed: 11/25/2022]
Abstract
We previously reported that hydrogen peroxide (H2O2) mediates mitogen activation of ribosomal protein S6 kinase 1 (S6K1) which plays an important role in cell proliferation and growth. In this study, we investigated a possible role of H2O2 as a molecular linker in Rac1 activation of S6K1. Overexpression of recombinant catalase in NIH-3T3 cells led to the drastic inhibition of H2O2 production by PDGF, which was accompanied by a decrease in S6K1 activity. Similarly, PDGF activation of S6K1 was significantly inhibited by transient transfection or stable transfection of the cells with a dominant-negative Rac1 (Rac1N17), while overexpression of constitutively active Rac1 (Rac1V12) in the cells led to an increase in basal activity of S6K1. In addition, stable transfection of Rat2 cells with Rac1N17 dramatically attenuated the H2O2 production by PDGF as compared with that in the control cells. In contrast, Rat2 cells stably transfected with Rac1V12 produced high level of H2O2 in the absence of PDGF, comparable to that in the control cells stimulated with PDGF. More importantly, elimination of H2O2 produced in Rat2 cells overexpressing Rac1V12 inhibited the Rac1V12 activation of S6K1, indicating the possible role of H2O2 as a mediator in the activation of S6K1 by Rac1. However, H2O2 could be also produced via other pathway, which is independent of Rac1 or PI3K, because in Rat2 cells stably transfected with Rac1N17, H2O2 could be produced by arsenite, which has been shown to be a stimulator of H2O2 production. Taken together, these results suggest that H2O2 plays a pivotal role as a mediator in Rac1 activation of S6K1.
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Affiliation(s)
- Gyu-Un Bae
- College of Pharmacy, Sungkyunkwan University, Suwon 440-746, South Korea
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Hornberger TA, Armstrong DD, Koh TJ, Burkholder TJ, Esser KA. Intracellular signaling specificity in response to uniaxial vs. multiaxial stretch: implications for mechanotransduction. Am J Physiol Cell Physiol 2004; 288:C185-94. [PMID: 15371259 DOI: 10.1152/ajpcell.00207.2004] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several lines of evidence suggest that muscle cells can distinguish between specific mechanical stimuli. To test this concept, we subjected C(2)C(12) myotubes to cyclic uniaxial or multiaxial stretch. Both types of stretch induced an increase in extracellular signal-regulated kinase (ERK) and protein kinase B (PKB/Akt) phosphorylation, but only multiaxial stretch induced ribosomal S6 kinase (p70(S6k)) phosphorylation. Further results demonstrated that the signaling events specific to multiaxial stretch (p70(S6k) phosphorylation) were elicited by forces delivered through the elastic culture membrane and were not due to greater surface area deformations or localized regions of large tensile strain. Experiments performed using medium that was conditioned by multiaxial stretched myotubes indicated that a release of paracrine factors was not sufficient for the induction of signaling to p70(S6k). Furthermore, incubation with gadolinium(III) chloride (500 microM), genistein (250 microM), PD-98059 (250 microM), bisindolylmaleimide I (20 microM), or LY-294002 (100 microM ) did not block the multiaxial stretch-induced signaling to p70(S6k). However, disrupting the actin cytoskeleton with cytochalasin D did block the multiaxial signaling to p70(S6k), with no effect on signaling to PKB/Akt. These results demonstrate that specific types of mechanical stretch activate distinct signaling pathways, and we propose that this occurs through direct mechanosensory-mechanotransduction mechanisms and not through previously defined growth factor/receptor binding pathways.
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Zahradka P, Litchie B, Storie B, Helwer G. Transactivation of the insulin-like growth factor-I receptor by angiotensin II mediates downstream signaling from the angiotensin II type 1 receptor to phosphatidylinositol 3-kinase. Endocrinology 2004; 145:2978-87. [PMID: 14976148 DOI: 10.1210/en.2004-0029] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (AngII) activates phosphatidylinositol 3-kinase (PI3-kinase), a known effector of receptor tyrosine kinases. Treatment of smooth muscle cells with AngII has also been shown to promote phosphorylation of various tyrosine kinase receptors. We therefore investigated the relationship between AngII and IGF-I receptor activation in smooth muscle cells with a phosphorylation-specific antibody. Our experiments showed that IGF-I receptor phosphorylation was maximally stimulated within 10 min by AngII. Inclusion of an IGF-I-neutralizing antibody in the culture media did not prevent IGF-I receptor phosphorylation after AngII treatment, which argues that a paracrine/autocrine loop is not required. Furthermore, this process was blocked by losartan and 1-(1,1-dimethylethyl)-1-(4-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (PP-1), indicating stimulation of IGF-I receptor phosphorylation occurs via AngII type 1 receptor-dependent activation of Src kinase. The functional significance of IGF-I receptor transactivation was examined with selective inhibitors of the IGF-I receptor kinase (AG1024, AG538). When AngII-treated cells were incubated with AG1024 or AG538, phosphorylation of the regulatory p85 subunit of PI3-kinase was blocked. Furthermore, phosphorylation of the downstream factor p70(S6K) did not occur. In contrast, AG1024 did not prevent MAPK or Src kinase activation by AngII. AG1024 also did not inhibit AngII-dependent cell migration, although this process was blocked by inhibitors of the epidermal growth factor and platelet-derived growth factor receptors. Transactivation of the IGF-I receptor is therefore a critical mediator of PI3-kinase activation by AngII but is not required for stimulation of the MAPK cascade.
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Affiliation(s)
- Peter Zahradka
- Institute of Cardiovascular Sciences, Molecular Physiology Laboratory, St. Boniface Research Centre, 351 Tache Avenue, Winnipeg, Maniotoba, Canada R2H 2A6.
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Abstract
As a master regulator of cellular processes ranging from cell growth and proliferation to differentiation, the mammalian target of rapamycin (mTOR) is critically involved in a complex signaling network. mTOR appears to govern an amino acid sensing pathway that integrates with a phosphatidylinositol 3-kinase-dependent mitogenic pathway to activate the downstream effectors. Recent findings have revealed some unexpected regulatory mechanisms of mTOR signaling. A direct link between mTOR and mitogenic signals is found to be mediated by the lipid second messenger phosphatidic acid. In addition, cytoplasmic-nuclear shuttling of mTOR appears to be required for the cytoplasmic functions of this protein. A new picture of the rapamycin-sensitive signaling network is emerging, with implications in putative upstream regulators and additional downstream targets for mTOR.
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Affiliation(s)
- J Chen
- Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, 601 S. Goodwin Ave. B107, Urbana, IL 61801, USA.
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Jung DK, Bae GU, Kim YK, Han SH, Choi WS, Kang H, Seo DW, Lee HY, Cho EJ, Lee HW, Han JW. Hydrogen peroxide mediates arsenite activation of p70(s6k) and extracellular signal-regulated kinase. Exp Cell Res 2003; 290:144-54. [PMID: 14516795 DOI: 10.1016/s0014-4827(03)00320-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To define the mechanism of arsenite-induced tumor promotion, we examined the role of reactive oxygen species (ROS) in the signaling pathways of cells exposed to arsenite. Arsenite treatment resulted in the persistent activation of p70(s6k) and extracellular signal-regulated kinase 1/2 (ERK1/2) which was accompanied by an increase in intracellular ROS production. The predominant produced appeared to be H(2)O(2), because the arsenite-induced increase in dichlorofluorescein (DCF) fluorescence was completely abolished by pretreatment with catalase but not with heat-inactivated catalase. Elimination of H(2)O(2) by catalase or N-acetyl-L-cysteine inhibited the arsenite-induced activation of p70(s6k) and ERK1/2, indicating the possible role of H(2)O(2) in the arsenite activation of the p70(s6k) and the ERK1/2 signaling pathways. A specific inhibitor of p70(s6k), rapamycin, and calcium chelators significantly blocked the activation of p70(s6k) induced by arsenite. While the phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002 completely abrogated arsenite activation of p70(s6k), ERK1/2 activation by arsenite was not affected by these inhibitors, indicating that H(2)O(2) might act as an upstream molecule of PI3K as well as ERK1/2. Consistent with these results, none of the inhibitors impaired H(2)O(2) production by arsenite. DNA binding activity of AP-1, downstream of ERK1/2, was also inhibited by catalase, N-acetyl-L-cysteine, and the MEK inhibitor PD98059, which significantly blocked arsenite activation of ERK1/2. Taken together, these studies provide insight into mechanisms of arsenite-induced tumor promotion and suggest that H(2)O(2) plays a critical role in tumor promotion by arsenite through activation of the ERK1/2 and p70(s6k) signaling pathways.
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Affiliation(s)
- Dong Keun Jung
- Department of Biochemistry and Molecular Biology, College of Pharmacy, Sungkyunkwan University, Suwon 440-746, Korea
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Tang X, Wang L, Proud CG, Downes CP. Muscarinic receptor-mediated activation of p70 S6 kinase 1 (S6K1) in 1321N1 astrocytoma cells: permissive role of phosphoinositide 3-kinase. Biochem J 2003; 374:137-43. [PMID: 12747804 PMCID: PMC1223574 DOI: 10.1042/bj20021910] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2002] [Revised: 05/12/2003] [Accepted: 05/15/2003] [Indexed: 11/17/2022]
Abstract
In 1321N1 astrocytoma cells, carbachol stimulation of M3 muscarinic cholinergic receptors, coupled to phospholipase C, evoked a persistent 10-20-fold activation of p70 S6 kinase (S6K1). This response was abolished by chelation of cytosolic Ca2+ and reproduced by the Ca2+ ionophore ionomycin, but was not prevented by down-regulation or inhibition of protein kinase C. Carbachol-stimulated activation and phosphorylation of S6K1 at Thr389 were prevented by rapamycin, an inhibitor of mTOR (mammalian target of rapamycin), or by wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor. Carbachol also stimulated the phosphorylation of eukaryotic initiation factor 4E-binding protein-1 (4E-BP1), a second mTOR-dependent event, with similar potency to its effect on S6K1. This response was blocked by rapamycin, but was not markedly affected by 100 nM wortmannin, implying separate roles for mTOR and PI3K in S6K1 activation. Wortmannin abolished the carbachol-stimulated rise in PtdIns(3,4,5)P3 and greatly reduced unstimulated levels of this lipid. By contrast, an inhibitor of epidermal growth factor receptor kinase, AG1478, which prevents carbachol-stimulated ErbB3 transactivation, PI3K recruitment and protein kinase B activation in 1321N1 cells, reduced activation of S6K1 by no more than 30%. This effect was overcome by 10 nM insulin, which on its own did not stimulate S6K1, but increased cellular PtdIns(3,4,5)P3 concentrations comparably with carbachol alone. These observations distinguish obligatory roles for mTOR and PI3K in regulating S6K1, but imply that minimal PI3K activity is sufficient to permit stimulation of S6K1 by other activating factors such as increased cytosolic Ca2+ concentrations, which are essential to the muscarinic receptor-mediated response. Moreover, 4E-BP1 and hence, presumably, mTOR can be regulated independently of PI3K activation through these mechanisms.
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Affiliation(s)
- Xiuwen Tang
- Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, UK
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Tai LK, Okuda M, Abe JI, Yan C, Berk BC. Fluid shear stress activates proline-rich tyrosine kinase via reactive oxygen species-dependent pathway. Arterioscler Thromb Vasc Biol 2002; 22:1790-6. [PMID: 12426206 DOI: 10.1161/01.atv.0000034475.40227.40] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Fluid shear stress (flow) modulates endothelial cell (EC) function via specific signal transduction events. Previously, we showed that flow-mediated tyrosine phosphorylation of p130 Crk-associated substrate (Cas) required calcium-dependent c-Src activation. Because flow increases reactive oxygen species (ROS) production in ECs and because H(2)O(2) increases tyrosine phosphorylation of proline-rich tyrosine kinase (PYK2), we hypothesized that flow may activate PYK2 via ROS. METHODS AND RESULTS Exposure of bovine aortic ECs to flow stimulated PYK2 phosphorylation rapidly, with a peak at 2 minutes. The activation of PYK2 and phosphorylation of Cas induced by flow were inhibited by pretreatment with the antioxidant N-acetylcysteine. Flow-induced PYK2 phosphorylation was inhibited by BAPTA-AM, an intracellular calcium chelator. Bovine aortic ECs transfected with kinase-inactive PYK2 showed attenuated flow-stimulated Cas tyrosine phosphorylation. Although flow-induced Cas phosphorylation was inhibited by kinase-inactive Src, PYK2 activation induced by flow was not inhibited by overexpression of kinase-inactive Src. CONCLUSIONS These results show a redox-sensitive pathway for flow-mediated activation of nonreceptor tyrosine kinase activity that requires ROS and intracellular calcium, but not Src kinase.
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Affiliation(s)
- Lung-Kuo Tai
- Center for Cardiovascular Research, University of Rochester, Rochester, NY 14642, USA
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37
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Abstract
Originally discovered as an anti-fungal agent, the bacterial macrolide rapamycin is a potent immunosuppressant and a promising anti-cancer drug. In complex with its cellular receptor, the FK506-binding protein (FKBP12), rapamycin binds and inhibits the function of the mammalian target of rapamycin (mTOR). By mediating amino acid sufficiency, mTOR governs signaling to translational regulation and other cellular functions by converging with the phosphatidylinositol 3-kinase (PI3K) pathway on downstream effectors. Whether mTOR receives mitogenic signals in addition to nutrient-sensing has been an unresolved issue, and the mechanism of action of rapamycin remained unknown. Our recent findings have revealed a novel link between mitogenic signals and mTOR via the lipid second messenger phosphatidic acid (PA), and suggested a role for mTOR in the integration of nutrient and mitogen signals. A molecular mechanism for rapamycin inhibition of mTOR signaling is proposed, in which a putative interaction between PA and mTOR is abolished by rapamycin binding. Collective evidence further implicates the regulation of the rapamycin-sensitive signaling circuitry by phospholipase D, and potentially by other upstream regulators such as the conventional protein kinase C, the Rho and ARF families of small G proteins, and calcium ions. As the mTOR pathway has been demonstrated to be an important anti-cancer target, the identification of new components and novel regulatory modes in mTOR signaling will facilitate the future development of diagnostic and therapeutic strategies.
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Affiliation(s)
- Jie Chen
- Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue, B107, Urbana, IL 61801, USA.
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Alpini G, Glaser S, Alvaro D, Ueno Y, Marzioni M, Francis H, Baiocchi L, Stati T, Barbaro B, Phinizy JL, Mauldin J, Lesage G. Bile acid depletion and repletion regulate cholangiocyte growth and secretion by a phosphatidylinositol 3-kinase-dependent pathway in rats. Gastroenterology 2002; 123:1226-37. [PMID: 12360484 DOI: 10.1053/gast.2002.36055] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS We tested the hypothesis that during bile duct obstruction, increased biliary bile acids trigger cholangiocyte proliferation and secretion by a phosphatidylinositol 3-kinase (PI3-K)-dependent pathway. METHODS In bile duct-incannulated (BDI) rats, bile duct obstruction present for 7 days was relieved for 24 hours by external bile drainage. During the 24-hour drainage period, animals received either Krebs Ringer Henseleit (the bile-depleted group), or sodium taurocholate (the bile-depleted, taurocholate-infused group). We evaluated cholangiocyte proliferation and secretin-stimulated ductal secretion. Apical bile acid transporter (ABAT) expression and bile acid transport activity was determined. In pure preparations of cholangiocytes, we examined the effect of taurocholate (in the absence or presence of wortmannin or PI 3,4-bisphosphate the lipid product of PI3-K) on cholangiocyte proliferation and secretin-stimulated cyclic adenosine 3',5'-monophosphate (cAMP) levels. RESULTS Bile depletion reduced cholangiocyte proliferation and secretin-stimulated ductal secretion and ABAT expression and bile acid transport activity compared with 1-week BDI control rats. In bile-depleted, taurocholate-infused rats, cholangiocyte proliferation and secretion and ABAT expression and bile acid transport activity were maintained at levels similar to those seen in BDI control rats. In vitro, taurocholate stimulation of DNA replication and secretin-stimulated cAMP levels was blocked by wortmannin. The inhibitory effect of wortmannin on taurocholate stimulation of cholangiocyte proliferation and secretion was prevented by PI 3,4-bisphosphate. CONCLUSIONS Bile acid uptake by ABAT and the PI3-K pathway are important for bile acids to signal cholangiocyte proliferation. In bile duct obstruction, increased biliary bile acid concentration and ABAT expression initiate increased cholangiocyte proliferation and secretion.
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Affiliation(s)
- Gianfranco Alpini
- Department of Internal Medicine, Scott & White Hospital and The Texas A&M University System Health Science Center College of Medicine, and Central Texas Veterans Health Care System, Temple, Texas, USA
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39
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Rodríguez‐Fernández JL, Sánchez‐Martín L, de Frutos CA, Sancho D, Robinson M, Sánchez‐Madrid F, Cabañas C. LFA‐1 integrin and the microtubular cytoskeleton are involved in the Ca
2
+
‐mediated regulation of the activity of the tyrosine kinase PYK2 in T cells. J Leukoc Biol 2002. [DOI: 10.1189/jlb.71.3.520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- José Luis Rodríguez‐Fernández
- Instituto de Farmacología y Toxicología (Centro Mixto CSIC‐UCM), Facultad de Medicina, Universidad Complutense, Madrid, Spain
| | - Lorena Sánchez‐Martín
- Instituto de Farmacología y Toxicología (Centro Mixto CSIC‐UCM), Facultad de Medicina, Universidad Complutense, Madrid, Spain
| | - Cristina Alvarez de Frutos
- Instituto de Farmacología y Toxicología (Centro Mixto CSIC‐UCM), Facultad de Medicina, Universidad Complutense, Madrid, Spain
| | - David Sancho
- Servicio de Inmunología, Hospital de la Princesa, Madrid, Spain; and
| | | | | | - Carlos Cabañas
- Instituto de Farmacología y Toxicología (Centro Mixto CSIC‐UCM), Facultad de Medicina, Universidad Complutense, Madrid, Spain
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40
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Lambert JM, Karnoub AE, Graves LM, Campbell SL, Der CJ. Role of MLK3-mediated activation of p70 S6 kinase in Rac1 transformation. J Biol Chem 2002; 277:4770-7. [PMID: 11713255 DOI: 10.1074/jbc.m109379200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The signaling pathways that mediate the transforming activity of the Rac1 GTPase remain to be determined. In the present study, we used effector domain mutants of the constitutively activated Rac(61L) mutant that display differential transforming activities and differential activation of downstream effector pathways to investigate the contribution of p70 S6 kinase (p70(S6K)) to Rac1 transformation and to decipher the signaling pathways leading from Rac1 to p70(S6K). First, we found that Rac1 transforming activity could be dissociated from Rac1 activation of p70(S6K). A weakly transforming Rac1 mutant retained the ability to activate p70(S6K), whereas some potently transforming effector mutants were impaired in their ability to activate p70(S6K). These data suggest that p70(S6K) is not necessary to promote full Rac1 transforming activity. We also found a strong correlation between the ability of the Rac(61L) effector mutants to activate p70(S6K) and their ability to activate the JNK mitogen-activated protein kinase. We found that the MLK3 serine/threonine kinase activated JNK and p70(S6K), whereas activation of p70(S6K) by Rac(61L) was significantly inhibited by dominant-negative MLK3. Additionally, the ability of the Rac(61L) effector mutants to activate MLK3 correlated well with their ability to activate p70(S6K) and JNK. Taken together, these results provide evidence that Rac1 coordinately activates p70(S6K) and JNK via MLK3 activation. Finally, we found that co-expression of wild type, but not kinase-dead, MLK3 significantly inhibited Rac1 transforming activity. These results suggest that MLK3 may be a negative regulator of the growth-promoting and transforming properties of Rac1.
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Affiliation(s)
- John M Lambert
- Lineberger Comprehensive Cancer Center, Department of Pharmacology and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7295, USA
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41
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Shah OJ, Iniguez-Lluhi JA, Romanelli A, Kimball SR, Jefferson LS. The activated glucocorticoid receptor modulates presumptive autoregulation of ribosomal protein S6 protein kinase, p70 S6K. J Biol Chem 2002; 277:2525-33. [PMID: 11705993 DOI: 10.1074/jbc.m105935200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Protein metabolism in eukaryotic organisms is defined by a synthesis-degradation equilibrium that is subject to regulation by hormonal and nutritional signals. In mammalian tissues such as skeletal muscle, glucocorticoid hormones specify a catabolic response that influences both protein synthetic and protein degradative pathways. With regard to the former, glucocorticoids attenuate mRNA translation at two levels: translational efficiency, i.e. translation initiation, and translational capacity, i.e. ribosome biogenesis. Glucocorticoids may impair translational capacity through the ribosomal S6 protein kinase (p70 S6K), a recognized glucocorticoid target and an effector of ribosomal protein synthesis. We demonstrate here that the reduction in growth factor-activated p70 S6K activity by glucocorticoids depends upon a functional glucocorticoid receptor (GR) and that the GR is both necessary and sufficient to render p70 S6K subject to glucocorticoid regulation. Furthermore, the DNA binding and transcriptional activation but not repression properties of the GR are indispensable for p70 S6K regulation. Finally, a mutational analysis of the p70 S6K carboxyl terminus indicates that this region confers glucocorticoid sensitivity, and thus glucocorticoids may facilitate autoinhibition of the enzyme ultimately reducing the efficiency with which T389 is phosphorylated.
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Affiliation(s)
- O Jameel Shah
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033-0850, USA
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42
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Willard FS, Berven LA, Crouch MF. Lysophosphatidic acid activates the 70-kDa S6 kinase via the lipoxygenase pathway. Biochem Biophys Res Commun 2001; 287:607-13. [PMID: 11563838 DOI: 10.1006/bbrc.2001.5645] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many hormones are known to activate the 70-kDa S6 kinase (p70(S6K)). The signalling pathways mediating p70(S6K) activation are only partially characterized. We investigate, in this report, the mechanisms by which lysophosphatidic acid (LPA) activates p70(S6K). We observed that p70(S6K) activation was conventional, in that it was sensitive to both rapamycin and PI3 kinase inhibition. p70(S6K) activation appeared to be caused by the activation of several phospholipase pathways. LPA was an effective stimulus of phospholipase C induced intracellular calcium mobilization, which appeared to participate in p70(S6K) activation. Similarly, the effect of LPA on p70(S6K) activity was antagonized by butan-1-ol but not butan-2-ol suggesting the involvement of agonist stimulated phospholipase D activity. Further, antagonism of the phospholipase A(2) and lipoxygenase pathways attenuated p70(S6K) activation indicating a novel mechanism of p70(S6K) regulation. We conclude that in Swiss 3T3 cells LPA coordinates activation of several phospholipases to regulate p70(S6K).
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Affiliation(s)
- F S Willard
- Molecular Signalling Group, Australian National University, Canberra, ACT 2601, Australia.
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43
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Rocic P, Lucchesi PA. Down-regulation by antisense oligonucleotides establishes a role for the proline-rich tyrosine kinase PYK2 in angiotensin ii-induced signaling in vascular smooth muscle. J Biol Chem 2001; 276:21902-6. [PMID: 11262415 DOI: 10.1074/jbc.m101684200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Abnormal vascular smooth muscle cell (VSMC) growth plays a key role in the pathogenesis of hypertension and atherosclerosis. Angiotensin II (Ang II) elicits a hypertrophic growth response characterized by an increase in protein synthesis in the absence of DNA synthesis and cell proliferation. Intracellular signaling mechanisms linking angiotensin type I receptor activation to protein synthesis in VSMC have not been fully characterized. The present study investigates the role of the nonreceptor proline-rich tyrosine kinase 2 (PYK2) in Ang II-induced VSMC protein synthesis and in the regulation of two signaling pathways that have been implicated in the control of protein synthesis, the extracellular signal-regulated kinase (ERK1/2) and the phosphatidylinositol 3-kinase/Akt pathways. PYK2 antisense oligonucleotides were used to down-regulate PYK2 expression in cultured VSMC. An 80% down-regulation in PYK2 expression resulted in an approximately 80% inhibition of ERK1/2 (3.8 +/- 1.3 versus 16.6 +/- 1.8), p70S6 kinase (1.03 +/- 0.03 versus 3.8 +/- 0.5), and Akt activation (3.0 +/- 0.8 versus 16.0 +/- 1.0) by Ang II. Furthermore, PYK2 down-regulation resulted in a complete inhibition of Ang II-induced VSMC protein synthesis. These data conclusively identify PYK2 as an upstream regulator of both the ERK1/2 and the phosphatidylinositol 3-kinase/Akt pathways that are involved in Ang II-induced VSMC protein synthesis.
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Affiliation(s)
- P Rocic
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0005, USA
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44
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Intracellular signals that control cell proliferation in mammalian balance epithelia: key roles for phosphatidylinositol-3 kinase, mammalian target of rapamycin, and S6 kinases in preference to calcium, protein kinase C, and mitogen-activated protein kinase. J Neurosci 2001. [PMID: 11160436 DOI: 10.1523/jneurosci.21-02-00570.2001] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In fish, amphibians, and birds, the loss of hair cells can evoke S-phase entry in supporting cells and the production of new cells that differentiate as replacement hair cells and supporting cells. Recent investigations have shown that supporting cells from mammalian vestibular epithelia will proliferate in limited numbers after hair cells have been killed. Exogenous growth factors such as glial growth factor 2 enhance this proliferation most potently when tested on vestibular epithelia from neonates. In this study, the intracellular signaling pathways that underlie the S-phase entry were surveyed by culturing epithelia in the presence of pharmacological inhibitors and activators. The results demonstrate that phosphatidylinositol 3-kinase is a key element in the signaling cascades that lead to the proliferation of cells in mammalian balance epithelia in vitro. Protein kinase C, mammalian target of rapamycin, mitogen-activated protein kinase, and calcium were also identified as elements in the signaling pathways that trigger supporting cell proliferation.
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Abstract
BACKGROUND Smooth muscle cells in vascular tissue, like tissue within the urogenital sinus, undergo growth and proliferation. METHODS This review attempts to compare and contrast the mechanisms and controlling factors involved in prostatic and vascular tissue. There is a particular focus on the role of catecholamines and alpha-adrenoceptors (alpha-ARs), and on the effects of alpha(1)-AR antagonists (blockers) on cellular dynamics. RESULTS AND CONCLUSIONS The situation in vascular tissue appears analagous to that in prostatic tissue. Certain AR-antagonists, in addition to altering smooth muscle contraction, may have other actions on cellular dynamics.
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Affiliation(s)
- B B Hoffman
- Department of Medicine, Stanford University School of Medicine, and Veterans Affairs Palo Alto Health Care System, Palo Alto, California 94304, USA.
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46
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Haendeler J, Berk BC. Angiotensin II mediated signal transduction. Important role of tyrosine kinases. REGULATORY PEPTIDES 2000; 95:1-7. [PMID: 11062326 DOI: 10.1016/s0167-0115(00)00133-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
It has been 100 years since the discovery of renin by Bergman and Tigerstedt. Since then, numerous studies have advanced our understanding of the renin-angiotensin system. A remarkable aspect was the discovery that angiotensin II (AngII) is the central product of the renin-angiotensin system and that this octapeptide induces multiple physiological responses in different cell types. In addition to its well known vasoconstrictive effects, growing evidence supports the notion that AngII may play a central role not only in hypertension, but also in cardiovascular and renal diseases. Binding of AngII to the seven-transmembrane angiotensin II type 1 receptor is responsible for nearly all of the physiological actions of AngII. Recent studies underscore the new concept that activation of intracellular second messengers by AngII requires tyrosine phosphorylation. An increasing number of tyrosine kinases have been shown to be activated by AngII, including the Src kinase family, the focal adhesion kinase family, the Janus kinases and receptor tyrosine kinases. These actions of AngII contribute to the pathophysiology of cardiac hypertrophy and remodeling, vascular thickening, heart failure and atherosclerosis. In this review, we discuss the important role of tyrosine kinases in AngII-mediated signal transduction. Understanding the importance of tyrosine phosphorylation in AngII-stimulated signaling events may contribute to new therapies for cardiovascular and renal diseases.
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Affiliation(s)
- J Haendeler
- Center for Cardiovascular Research, University of Rochester, Rochester, NY, USA.
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47
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Govindarajan G, Eble DM, Lucchesi PA, Samarel AM. Focal adhesion kinase is involved in angiotensin II-mediated protein synthesis in cultured vascular smooth muscle cells. Circ Res 2000; 87:710-6. [PMID: 11029408 DOI: 10.1161/01.res.87.8.710] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The rate of vascular smooth muscle cell protein synthesis and cellular hypertrophy in response to angiotensin II (Ang II) is dependent on activation of protein tyrosine kinases (PTKs) and both the extracellular signal-regulated kinase (ERK) 1/2 and p70(S6K) pathways. One potential PTK that may regulate these signaling cascades is focal adhesion kinase (FAK), a nonreceptor PTK associated with focal adhesions. We used an actin depolymerizing agent, cytochalasin D (Cyt-D), and a replication-defective adenovirus encoding FAK-related nonkinase (FRNK), an inhibitor of FAK-dependent signaling, as tools to assess whether FAK was upstream of the ERK1/2 and/or the p70(S6K) pathways. Cyt-D reduced basal FAK phosphorylation and blocked Ang II-dependent FAK phosphorylation in a dose-dependent manner. Confocal microscopy indicated that Cyt-D induced actin filament disruption and FAK delocalization from focal adhesions. Cyt-D also reduced Ang II-induced ERK1/2 activation, but p70(S6K) activation was relatively unaffected. Cyt-D reduced basal protein synthetic rate and substantially reduced the Ang II-induced increase in protein synthesis. Similarly, FRNK overexpression blocked Ang II-induced FAK phosphorylation and ERK1/2 activation, but not p70(S6K) phosphorylation, and markedly inhibited protein synthesis. This is the first report to demonstrate that FAK is a critical component of the signal transduction pathways that mediate Ang II-induced ERK1/2 activation, c-fos induction, and enhanced protein synthesis in vascular smooth muscle cells.
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MESH Headings
- Actins/metabolism
- Adenoviridae/genetics
- Angiotensin II/metabolism
- Angiotensin II/pharmacology
- Animals
- Cells, Cultured
- Cytoskeleton/drug effects
- Cytoskeleton/metabolism
- Enzyme Inhibitors/pharmacology
- Focal Adhesion Kinase 1
- Focal Adhesion Protein-Tyrosine Kinases
- Gene Expression Regulation/drug effects
- Mitogen-Activated Protein Kinase 1/antagonists & inhibitors
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Phosphorylation/drug effects
- Protein Biosynthesis
- Protein Synthesis Inhibitors/pharmacology
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins c-fos/genetics
- Proto-Oncogene Proteins c-fos/metabolism
- RNA, Messenger/biosynthesis
- RNA, Ribosomal, 18S/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Ribosomal Protein S6 Kinases/metabolism
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Affiliation(s)
- G Govindarajan
- Cardiovascular Institute, Loyola University Chicago, Maywood, IL 60153, USA
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48
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Kim S, Jung Y, Kim D, Koh H, Chung J. Extracellular zinc activates p70 S6 kinase through the phosphatidylinositol 3-kinase signaling pathway. J Biol Chem 2000; 275:25979-84. [PMID: 10851233 DOI: 10.1074/jbc.m001975200] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have studied a possible role of extracellular zinc ion in the activation of p70S6k, which plays an important role in the progression of cells from the G(1) to S phase of the cell cycle. Treatment of Swiss 3T3 cells with zinc sulfate led to the activation and phosphorylation of p70S6k in a dose-dependent manner. The activation of p70S6k by zinc treatment was biphasic, the early phase being at 30 min followed by the late phase at 120 min. The zinc-induced activation of p70S6k was partially inhibited by down-regulation of phorbol 12-myristate 13-acetate-responsive protein kinase C (PKC) by chronic treatment with phorbol 12-myristate 13-acetate, but this was not significant. Moreover, Go6976, a specific calcium-dependent PKC inhibitor, did not significantly inhibit the activation of p70S6k by zinc. These results demonstrate that the zinc-induced activation of p70S6k is not related to PKC. Also, extracellular calcium was not involved in the activation of p70S6k by zinc. Further characterization of the zinc-induced activation of p70S6k using specific inhibitors of the p70S6k signaling pathway, namely rapamycin, wortmannin, and LY294002, showed that zinc acted upstream of mTOR/FRAP/RAFT and phosphatidylinositol 3-kinase (PI3K), because these inhibitors caused the inhibition of zinc-induced p70S6k activity. In addition, Akt, the upstream component of p70S6k, was activated by zinc in a biphasic manner, as was p70S6k. Moreover, dominant interfering alleles of Akt and PDK1 blocked the zinc-induced activation of p70S6k, whereas the lipid kinase activity of PI3K was potently activated by zinc. Taken together, our data suggest that zinc activates p70S6k through the PI3K signaling pathway.
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Affiliation(s)
- S Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong, Taejon 305-701, Republic of Korea
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Eguchi S, Inagami T. Signal transduction of angiotensin II type 1 receptor through receptor tyrosine kinase. REGULATORY PEPTIDES 2000; 91:13-20. [PMID: 10967198 DOI: 10.1016/s0167-0115(00)00126-9] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In cultured vascular smooth muscle cells, the angiotensin II (AngII) type-1 (AT(1)) receptor generates growth-promoting signals via the epidermal growth factor (EGF) receptor system. This 'transactivation' mechanism now appears to be utilized by a variety of G-protein-coupled receptors in many cells. The AngII-induced EGF receptor transactivation leads to activation of downstream signaling molecules including Ras, ERK, c-fos, Akt/protein kinase B, and p70 S6 kinase. We propose three possible mechanisms may be involved in the transactivation, (i) an upstream tyrosine kinase, (ii) reactive oxygen species, and (iii) a juxtacrine activation of the EGF receptor ligand. Whether the EGF receptor signal transduction induced by AngII plays an essential role in cardiovascular remodeling remains to be investigated.
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Affiliation(s)
- S Eguchi
- Department of Biochemistry, Vanderbilt University School of Medicine, 37232, Nashville, TN 37232, USA.
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50
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Tang H, Zhao ZJ, Landon EJ, Inagami T. Regulation of calcium-sensitive tyrosine kinase Pyk2 by angiotensin II in endothelial cells. Roles of Yes tyrosine kinase and tyrosine phosphatase SHP-2. J Biol Chem 2000; 275:8389-96. [PMID: 10722671 DOI: 10.1074/jbc.275.12.8389] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium-sensitive tyrosine kinase Pyk2 has been implicated in the regulation of ion channels, cellular adhesion, and mitogenic and hypertrophic reactions. In this study, we have investigated the regulation of Pyk2 by angiotensin II (Ang II) in pulmonary vein endothelial cells. We found that the Ang II-induced tyrosine phosphorylation of Pyk2, which requires the activity of Src family kinase, was specifically regulated by the Src family kinase member, Yes kinase. Moreover, we identified for the first time the constitutive association of Pyk2 with an Src homology 2 (SH2) domain-containing tyrosine phosphatase SHP-2. SHP-2 interacts with Pyk2 through a region other than its SH2 domains. Pyk2 can be dephosphorylated in vitro in SHP-2 immunoprecipitates and in intact cells expressing an NH(2) terminus-truncated form of SHP-2, which lacks the two SH2 domains but has an enhanced phosphatase activity. Ang II activates the endogenous SHP-2. Finally, the SHP-2-mediated dephosphorylation of Pyk2 correlates with the negative effect of SHP-2 on the Ang II-induced activation of extracellular signal-regulated kinase and c-Jun NH(2)-terminal kinase. Thus, the balance of Pyk2 tyrosine phosphorylation in response to Ang II is controlled by Yes kinase and by a tyrosine phosphatase SHP-2 in endothelial cells.
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MESH Headings
- Angiotensin II/metabolism
- Animals
- Endothelium, Vascular/cytology
- Endothelium, Vascular/physiology
- Focal Adhesion Kinase 2
- Intracellular Signaling Peptides and Proteins
- JNK Mitogen-Activated Protein Kinases
- Mitogen-Activated Protein Kinases/metabolism
- Phosphorylation
- Protein Binding
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/metabolism
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-fyn
- Proto-Oncogene Proteins c-yes
- Pulmonary Veins/cytology
- Rats
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/metabolism
- SH2 Domain-Containing Protein Tyrosine Phosphatases
- Signal Transduction
- Tyrosine/metabolism
- src-Family Kinases/metabolism
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Affiliation(s)
- H Tang
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
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