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Ramos-Kuri M, Meka SH, Salamanca-Buentello F, Hajjar RJ, Lipskaia L, Chemaly ER. Molecules linked to Ras signaling as therapeutic targets in cardiac pathologies. Biol Res 2021; 54:23. [PMID: 34344467 PMCID: PMC8330049 DOI: 10.1186/s40659-021-00342-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/26/2021] [Indexed: 12/11/2022] Open
Abstract
Abstract The Ras family of small Guanosine Triphosphate (GTP)-binding proteins (G proteins) represents one of the main components of intracellular signal transduction required for normal cardiac growth, but is also critically involved in the development of cardiac hypertrophy and heart failure. The present review provides an update on the role of the H-, K- and N-Ras genes and their related pathways in cardiac diseases. We focus on cardiac hypertrophy and heart failure, where Ras has been studied the most. We also review other cardiac diseases, like genetic disorders related to Ras. The scope of the review extends from fundamental concepts to therapeutic applications. Although the three Ras genes have a nearly identical primary structure, there are important functional differences between them: H-Ras mainly regulates cardiomyocyte size, whereas K-Ras regulates cardiomyocyte proliferation. N-Ras is the least studied in cardiac cells and is less associated to cardiac defects. Clinically, oncogenic H-Ras causes Costello syndrome and facio-cutaneous-skeletal syndromes with hypertrophic cardiomyopathy and arrhythmias. On the other hand, oncogenic K-Ras and alterations of other genes of the Ras-Mitogen-Activated Protein Kinase (MAPK) pathway, like Raf, cause Noonan syndrome and cardio-facio-cutaneous syndromes characterized by cardiac hypertrophy and septal defects. We further review the modulation by Ras of key signaling pathways in the cardiomyocyte, including: (i) the classical Ras-Raf-MAPK pathway, which leads to a more physiological form of cardiac hypertrophy; as well as other pathways associated with pathological cardiac hypertrophy, like (ii) The SAPK (stress activated protein kinase) pathways p38 and JNK; and (iii) The alternative pathway Raf-Calcineurin-Nuclear Factor of Activated T cells (NFAT). Genetic alterations of Ras isoforms or of genes in the Ras-MAPK pathway result in Ras-opathies, conditions frequently associated with cardiac hypertrophy or septal defects among other cardiac diseases. Several studies underline the potential role of H- and K-Ras as a hinge between physiological and pathological cardiac hypertrophy, and as potential therapeutic targets in cardiac hypertrophy and failure. Graphic abstract ![]()
The Ras (Rat Sarcoma) gene family is a group of small G proteins Ras is regulated by growth factors and neurohormones affecting cardiomyocyte growth and hypertrophy Ras directly affects cardiomyocyte physiological and pathological hypertrophy Genetic alterations of Ras and its pathways result in various cardiac phenotypes Ras and its pathway are differentially regulated in acquired heart disease Ras modulation is a promising therapeutic target in various cardiac conditions.
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Affiliation(s)
- Manuel Ramos-Kuri
- Instituto Nacional de Cancerología, Unidad de Investigación Biomédica en Cáncer, Secretarìa de Salud/Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, México.,Researcher of the Facultad de Bioética, Cátedra de Infertilidad, Universidad Anáhuac, Mexico City, México.,Centro de Investigación en Bioética y Genética, Querétaro, México
| | - Sri Harika Meka
- Division of Nephrology, Department of Medicine, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Clinical and Translational Research Center, 875 Ellicott Street, Suite 8030B, Buffalo, NY, 14203, USA
| | - Fabio Salamanca-Buentello
- University of Toronto Institute of Medical Science, Medical Sciences Building, 1 King's College Circle, Room 2374, Toronto, ON, M5S 1A8, Canada
| | | | - Larissa Lipskaia
- INSERM U955 and Département de Physiologie, Hôpital Henri Mondor, FHU SENEC, AP-HP, and Université Paris-Est Créteil (UPEC), 94010, Créteil, France
| | - Elie R Chemaly
- Division of Nephrology, Department of Medicine, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Clinical and Translational Research Center, 875 Ellicott Street, Suite 8030B, Buffalo, NY, 14203, USA.
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Key Enzymes for the Mevalonate Pathway in the Cardiovascular System. J Cardiovasc Pharmacol 2021; 77:142-152. [PMID: 33538531 DOI: 10.1097/fjc.0000000000000952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 10/15/2020] [Indexed: 11/25/2022]
Abstract
ABSTRACT Isoprenylation is an important post-transcriptional modification of small GTPases required for their activation and function. Isoprenoids, including farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate, are indispensable for isoprenylation by serving as donors of a prenyl moiety to small G proteins. In the human body, isoprenoids are mainly generated by the mevalonate pathway (also known as the cholesterol-synthesis pathway). The hydroxymethylglutaryl coenzyme A reductase catalyzes the first rate-limiting steps of the mevalonate pathway, and its inhibitor (statins) are widely used as lipid-lowering agents. In addition, the FPP synthase is also of critical importance for the regulation of the isoprenoids production, for which the inhibitor is mainly used in the treatment of osteoporosis. Synthetic FPP can be further used to generate geranylgeranyl pyrophosphate and cholesterol. Recent studies suggest a role for isoprenoids in the genesis and development of cardiovascular disorders, such as pathological cardiac hypertrophy, fibrosis, endothelial dysfunction, and fibrotic responses of smooth-muscle cells. Furthermore, statins and FPP synthase inhibitors have also been applied for the management of heart failure and other cardiovascular diseases rather than their clinical use for hyperlipidemia or bone diseases. In this review, we focus on the function of several critical enzymes, including hydroxymethylglutaryl coenzyme A reductase, FPP synthase, farnesyltransferase, and geranylgeranyltransferase in the mevalonate pathway which are involved in regulating the generation of isoprenoids and isoprenylation of small GTPases, and their pathophysiological role in the cardiovascular system. Moreover, we summarize recent research into applications of statins and the FPP synthase inhibitors to treat cardiovascular diseases, rather than for their traditional indications respectively.
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Blackwood EA, Hofmann C, Santo Domingo M, Bilal AS, Sarakki A, Stauffer W, Arrieta A, Thuerauf DJ, Kolkhorst FW, Müller OJ, Jakobi T, Dieterich C, Katus HA, Doroudgar S, Glembotski CC. ATF6 Regulates Cardiac Hypertrophy by Transcriptional Induction of the mTORC1 Activator, Rheb. Circ Res 2019; 124:79-93. [PMID: 30582446 DOI: 10.1161/circresaha.118.313854] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Endoplasmic reticulum (ER) stress dysregulates ER proteostasis, which activates the transcription factor, ATF6 (activating transcription factor 6α), an inducer of genes that enhance protein folding and restore ER proteostasis. Because of increased protein synthesis, it is possible that protein folding and ER proteostasis are challenged during cardiac myocyte growth. However, it is not known whether ATF6 is activated, and if so, what its function is during hypertrophic growth of cardiac myocytes. OBJECTIVE To examine the activity and function of ATF6 during cardiac hypertrophy. METHODS AND RESULTS We found that ER stress and ATF6 were activated and ATF6 target genes were induced in mice subjected to an acute model of transverse aortic constriction, or to free-wheel exercise, both of which promote adaptive cardiac myocyte hypertrophy with preserved cardiac function. Cardiac myocyte-specific deletion of Atf6 (ATF6 cKO [conditional knockout]) blunted transverse aortic constriction and exercise-induced cardiac myocyte hypertrophy and impaired cardiac function, demonstrating a role for ATF6 in compensatory myocyte growth. Transcript profiling and chromatin immunoprecipitation identified RHEB (Ras homologue enriched in brain) as an ATF6 target gene in the heart. RHEB is an activator of mTORC1 (mammalian/mechanistic target of rapamycin complex 1), a major inducer of protein synthesis and subsequent cell growth. Both transverse aortic constriction and exercise upregulated RHEB, activated mTORC1, and induced cardiac hypertrophy in wild type mouse hearts but not in ATF6 cKO hearts. Mechanistically, knockdown of ATF6 in neonatal rat ventricular myocytes blocked phenylephrine- and IGF1 (insulin-like growth factor 1)-mediated RHEB induction, mTORC1 activation, and myocyte growth, all of which were restored by ectopic RHEB expression. Moreover, adeno-associated virus 9- RHEB restored cardiac growth to ATF6 cKO mice subjected to transverse aortic constriction. Finally, ATF6 induced RHEB in response to growth factors, but not in response to other activators of ATF6 that do not induce growth, indicating that ATF6 target gene induction is stress specific. CONCLUSIONS Compensatory cardiac hypertrophy activates ER stress and ATF6, which induces RHEB and activates mTORC1. Thus, ATF6 is a previously unrecognized link between growth stimuli and mTORC1-mediated cardiac growth.
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Affiliation(s)
- Erik A Blackwood
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Christoph Hofmann
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.).,Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Michelle Santo Domingo
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Alina S Bilal
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Anup Sarakki
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Winston Stauffer
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Adrian Arrieta
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Donna J Thuerauf
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Fred W Kolkhorst
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Oliver J Müller
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Department of Internal Medicine III, University of Kiel, Germany, and German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany (O.J.M.)
| | - Tobias Jakobi
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III, University Hospital Heidelberg, Germany (T.J., C.D.)
| | - Christoph Dieterich
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III, University Hospital Heidelberg, Germany (T.J., C.D.)
| | - Hugo A Katus
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Shirin Doroudgar
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Christopher C Glembotski
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
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Liu R, Kenney JW, Manousopoulou A, Johnston HE, Kamei M, Woelk CH, Xie J, Schwarzer M, Garbis SD, Proud CG. Quantitative Non-canonical Amino Acid Tagging (QuaNCAT) Proteomics Identifies Distinct Patterns of Protein Synthesis Rapidly Induced by Hypertrophic Agents in Cardiomyocytes, Revealing New Aspects of Metabolic Remodeling. Mol Cell Proteomics 2016; 15:3170-3189. [PMID: 27512079 PMCID: PMC5054342 DOI: 10.1074/mcp.m115.054312] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Indexed: 01/16/2023] Open
Abstract
Cardiomyocytes undergo growth and remodeling in response to specific pathological or physiological conditions. In the former, myocardial growth is a risk factor for cardiac failure and faster protein synthesis is a major factor driving cardiomyocyte growth. Our goal was to quantify the rapid effects of different pro-hypertrophic stimuli on the synthesis of specific proteins in ARVC and to determine whether such effects are caused by alterations on mRNA abundance or the translation of specific mRNAs. Cardiomyocytes have very low rates of protein synthesis, posing a challenging problem in terms of studying changes in the synthesis of specific proteins, which also applies to other nondividing primary cells. To study the rates of accumulation of specific proteins in these cells, we developed an optimized version of the Quantitative Noncanonical Amino acid Tagging LC/MS proteomic method to label and selectively enrich newly synthesized proteins in these primary cells while eliminating the suppressive effects of pre-existing and highly abundant nonisotope-tagged polypeptides. Our data revealed that a classical pathologic (phenylephrine; PE) and the recently identified insulin stimulus that also contributes to the development of pathological cardiac hypertrophy (insulin), both increased the synthesis of proteins involved in, e.g. glycolysis, the Krebs cycle and beta-oxidation, and sarcomeric components. However, insulin increased synthesis of many metabolic enzymes to a greater extent than PE. Using a novel validation method, we confirmed that synthesis of selected candidates is indeed up-regulated by PE and insulin. Synthesis of all proteins studied was up-regulated by signaling through mammalian target of rapamycin complex 1 without changes in their mRNA levels, showing the key importance of translational control in the rapid effects of hypertrophic stimuli. Expression of PKM2 was up-regulated in rat hearts following TAC. This isoform possesses specific regulatory properties, so this finding indicates it may be involved in metabolic remodeling and also serve as a novel candidate biomarker. Levels of translation factor eEF1 also increased during TAC, likely contributing to faster cell mass accumulation. Interestingly those two candidates were not up-regulated in pregnancy or exercise induced CH, indicating PKM2 and eEF1 were pathological CH specific markers. We anticipate that the methodologies described here will be valuable for other researchers studying protein synthesis in primary cells.
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Affiliation(s)
- Rui Liu
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom; §South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia
| | - Justin W Kenney
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Antigoni Manousopoulou
- From the ‡Center for Proteomic Research, Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom; ¶Clinical and Experimental Sciences Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Harvey E Johnston
- From the ‡Center for Proteomic Research, Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom; ‖Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Makoto Kamei
- §South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia
| | - Christopher H Woelk
- ¶Clinical and Experimental Sciences Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Jianling Xie
- §South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia
| | - Michael Schwarzer
- **Department of Cardiovascular Surgery, Jena University Hospital-Friedrich Schiller University of Jena, Erlanger Allee 101, 07747 Jena, Germany
| | - Spiros D Garbis
- From the ‡Center for Proteomic Research, Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom; ¶Clinical and Experimental Sciences Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK; ‖Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK;
| | - Christopher G Proud
- From the ‡Center for Proteomic Research, Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom; §South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia; School of Biological Sciences, University of Adelaide, Adelaide, SA5005, Australia
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Inhibition of MAPK pathway is essential for suppressing Rheb-Y35N driven tumor growth. Oncogene 2016; 36:756-765. [PMID: 27399332 DOI: 10.1038/onc.2016.246] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/08/2016] [Accepted: 06/01/2016] [Indexed: 11/08/2022]
Abstract
Rheb is a Ras family GTPase, which binds to and activates mammalian target of rapamycin complex 1 (mTORC1) when GTP loaded. Recently, cancer genome sequencing efforts have identified recurrent Rheb Tyr35Asn mutations in kidney and endometrial carcinoma. Here we show that Rheb-Y35N causes not only constitutive mTORC1 activation, but sustained activation of the MEK-ERK pathway in a TSC1/TSC2/TBC1D7 protein complex and mTORC1-independent manner, contributing to intrinsic resistance to rapamycin. Rheb-Y35N transforms NIH3T3 cells, resulting in aggressive tumor formation in xenograft nude mice, which could be suppressed by combined treatment with rapamycin and an extracellular signal-regulated kinase (ERK) inhibitor. Furthermore, Rheb-Y35N inhibits AMPKα activation in response to nutrient depletion or 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), leading to attenuated phosphorylation of BRAF-S729 and retained mitogen-activated protein kinase (MAPK) activation. Finally, we demonstrate that Rheb-WT can bind AMPK to facilitate AMPK activation, whereas Rheb-Y35N competitively binds AMPK, impairing AMPK phosphorylation. In summary, our findings indicate that Rheb-Y35N is a dominantly active tumor driver that activates both mTORC1 and MAPK to promote tumor growth, suggesting a combination of mTORC1 and MAPK inhibitors may be of therapeutic value in patients whose cancers sustain this mutation.
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Tan VP, Miyamoto S. Nutrient-sensing mTORC1: Integration of metabolic and autophagic signals. J Mol Cell Cardiol 2016; 95:31-41. [PMID: 26773603 DOI: 10.1016/j.yjmcc.2016.01.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/11/2015] [Accepted: 01/04/2016] [Indexed: 12/26/2022]
Abstract
The ability of adult cardiomyocytes to regenerate is limited, and irreversible loss by cell death plays a crucial role in heart diseases. Autophagy is an evolutionarily conserved cellular catabolic process through which long-lived proteins and damaged organelles are targeted for lysosomal degradation. Autophagy is important in cardiac homeostasis and can serve as a protective mechanism by providing an energy source, especially in the face of sustained starvation. Cellular metabolism is closely associated with cell survival, and recent evidence suggests that metabolic and autophagic signaling pathways exhibit a high degree of crosstalk and are functionally interdependent. In this review, we discuss recent progress in our understanding of regulation of autophagy and its crosstalk with metabolic signaling, with a focus on the nutrient-sensing mTOR complex 1 (mTORC1) pathway.
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Affiliation(s)
- Valerie P Tan
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA
| | - Shigeki Miyamoto
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, USA.
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Bnip3 Binds and Activates p300: Possible Role in Cardiac Transcription and Myocyte Morphology. PLoS One 2015; 10:e0136847. [PMID: 26317696 PMCID: PMC4552727 DOI: 10.1371/journal.pone.0136847] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 07/17/2015] [Indexed: 12/04/2022] Open
Abstract
Bnip3 is a hypoxia-regulated member of the Bcl-2 family of proteins that is implicated in apoptosis, programmed necrosis, autophagy and mitophagy. Mitochondria are thought to be the primary targets of Bnip3 although its activities may extend to the ER, cytoplasm, and nucleus. Bnip3 is induced in the heart by ischemia and pressure-overload, and may contribute to cardiomyopathy and heart failure. Only mitochondrial-dependent programmed death actions have been described for Bnip3 in the heart. Here we describe a novel activity of Bnip3 in cultured cardiac myocytes and transgenic mice overexpressing Bnip3 in the heart (Bnip3-TG). In cultured myocytes Bnip3 bound and activated the acetyltransferase p300, increased acetylation of histones and the transcription factor GATA4, and conferred p300 and GATA4-sensitive cellular morphological changes. In intact Bnip3-TG hearts Bnip3 also bound p300 and GATA4 and conferred enhanced GATA4 acetylation. Bnip3-TG mice underwent age-dependent ventricular dilation and heart failure that was partially prevented by p300 inhibition with curcumin. The results suggest that Bnip3 regulates cardiac gene expression and perhaps myocyte morphology by activating nuclear p300 acetyltransferase activity and hyperacetylating histones and p300-selective transcription factors.
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Rheb Inhibits Protein Synthesis by Activating the PERK-eIF2α Signaling Cascade. Cell Rep 2015; 10:684-693. [PMID: 25660019 DOI: 10.1016/j.celrep.2015.01.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 12/04/2014] [Accepted: 12/31/2014] [Indexed: 11/20/2022] Open
Abstract
Rheb, a ubiquitous small GTPase, is well known to bind and activate mTOR, which augments protein synthesis. Inhibition of protein synthesis is also physiologically regulated. Thus, with cell stress, the unfolded protein response system leads to phosphorylation of the initiation factor eIF2α and arrest of protein synthesis. We now demonstrate a major role for Rheb in inhibiting protein synthesis by enhancing the phosphorylation of eIF2α by protein kinase-like ER kinase (PERK). Interplay between the stimulatory and inhibitory roles of Rheb may enable cells to modulate protein synthesis in response to varying environmental stresses.
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9
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Xu N, Guan S, Chen Z, Yu Y, Xie J, Pan FY, Zhao NW, Liu L, Yang ZZ, Gao X, Xu B, Li CJ. The alteration of protein prenylation induces cardiomyocyte hypertrophy through Rheb-mTORC1 signalling and leads to chronic heart failure. J Pathol 2015; 235:672-85. [DOI: 10.1002/path.4480] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 10/25/2014] [Accepted: 11/05/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Na Xu
- Ministry of Education Key Laboratory of Model Animals for Disease Study; Model Animal Research Centre and Medical School of Nanjing University, National Resource Centre for Mutant Mice; Nanjing People's Republic of China
| | - Shan Guan
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology; College of Life Science, Nanjing Normal University; Nanjing People's Republic of China
| | - Zhong Chen
- Ministry of Education Key Laboratory of Model Animals for Disease Study; Model Animal Research Centre and Medical School of Nanjing University, National Resource Centre for Mutant Mice; Nanjing People's Republic of China
| | - Yang Yu
- State Key Laboratory of Reproductive Biology; Institute of Zoology/Chinese Academy of Sciences; Beijing People's Republic of China
| | - Jun Xie
- Department of Cardiology; Affiliated Drum Tower Hospital of Nanjing University Medical School; Nanjing People's Republic of China
| | - Fei-Yan Pan
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology; College of Life Science, Nanjing Normal University; Nanjing People's Republic of China
| | - Ning-Wei Zhao
- Biomedical Research Laboratory; Shimadzu (China) Co. Ltd; Shanghai People's Republic of China
| | - Li Liu
- Department of Geriatrics; First Affiliated Hospital with Nanjing Medical University; Nanjing People's Republic of China
| | - Zhong-Zhou Yang
- Ministry of Education Key Laboratory of Model Animals for Disease Study; Model Animal Research Centre and Medical School of Nanjing University, National Resource Centre for Mutant Mice; Nanjing People's Republic of China
| | - Xiang Gao
- Ministry of Education Key Laboratory of Model Animals for Disease Study; Model Animal Research Centre and Medical School of Nanjing University, National Resource Centre for Mutant Mice; Nanjing People's Republic of China
| | - Biao Xu
- Department of Cardiology; Affiliated Drum Tower Hospital of Nanjing University Medical School; Nanjing People's Republic of China
| | - Chao-Jun Li
- Ministry of Education Key Laboratory of Model Animals for Disease Study; Model Animal Research Centre and Medical School of Nanjing University, National Resource Centre for Mutant Mice; Nanjing People's Republic of China
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Hasumi Y, Baba M, Hasumi H, Huang Y, Lang M, Reindorf R, Oh HB, Sciarretta S, Nagashima K, Haines DC, Schneider MD, Adelstein RS, Schmidt LS, Sadoshima J, Marston Linehan W. Folliculin (Flcn) inactivation leads to murine cardiac hypertrophy through mTORC1 deregulation. Hum Mol Genet 2014; 23:5706-19. [PMID: 24908670 DOI: 10.1093/hmg/ddu286] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cardiac hypertrophy, an adaptive process that responds to increased wall stress, is characterized by the enlargement of cardiomyocytes and structural remodeling. It is stimulated by various growth signals, of which the mTORC1 pathway is a well-recognized source. Here, we show that loss of Flcn, a novel AMPK-mTOR interacting molecule, causes severe cardiac hypertrophy with deregulated energy homeostasis leading to dilated cardiomyopathy in mice. We found that mTORC1 activity was upregulated in Flcn-deficient hearts, and that rapamycin treatment significantly reduced heart mass and ameliorated cardiac dysfunction. Phospho-AMP-activated protein kinase (AMPK)-alpha (T172) was reduced in Flcn-deficient hearts and nonresponsive to various stimulations including metformin and AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide). ATP levels were elevated and mitochondrial function was increased in Flcn-deficient hearts, suggesting that excess energy resulting from up-regulated mitochondrial metabolism under Flcn deficiency might attenuate AMPK activation. Expression of Ppargc1a, a central molecule for mitochondrial metabolism, was increased in Flcn-deficient hearts and indeed, inactivation of Ppargc1a in Flcn-deficient hearts significantly reduced heart mass and prolonged survival. Ppargc1a inactivation restored phospho-AMPK-alpha levels and suppressed mTORC1 activity in Flcn-deficient hearts, suggesting that up-regulated Ppargc1a confers increased mitochondrial metabolism and excess energy, leading to inactivation of AMPK and activation of mTORC1. Rapamycin treatment did not affect the heart size of Flcn/Ppargc1a doubly inactivated hearts, further supporting the idea that Ppargc1a is the critical element leading to deregulation of the AMPK-mTOR-axis and resulting in cardiac hypertrophy under Flcn deficiency. These data support an important role for Flcn in cardiac homeostasis in the murine model.
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Affiliation(s)
- Yukiko Hasumi
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Masaya Baba
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hisashi Hasumi
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ying Huang
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Martin Lang
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rachel Reindorf
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hyoung-bin Oh
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sebastiano Sciarretta
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101, USA, IRCCS Neuromed, Località Camerelle, 86077, Pozzilli (IS), Italy
| | | | | | - Michael D Schneider
- British Heart Foundation Centre of Research Excellence, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Robert S Adelstein
- Laboratory of Molecular Cardiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA and
| | - Laura S Schmidt
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA, Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101, USA
| | - W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA,
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11
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Cao Y, Tao L, Shen S, Xiao J, Wu H, Li B, Wu X, Luo W, Xiao Q, Hu X, Liu H, Nie J, Lu S, Yuan B, Han Z, Xiao B, Yang Z, Li X. Cardiac ablation of Rheb1 induces impaired heart growth, endoplasmic reticulum-associated apoptosis and heart failure in infant mice. Int J Mol Sci 2013; 14:24380-98. [PMID: 24351823 PMCID: PMC3876117 DOI: 10.3390/ijms141224380] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 11/25/2013] [Accepted: 12/03/2013] [Indexed: 11/19/2022] Open
Abstract
Ras homologue enriched in brain 1 (Rheb1) plays an important role in a variety of cellular processes. In this study, we investigate the role of Rheb1 in the post-natal heart. We found that deletion of the gene responsible for production of Rheb1 from cardiomyocytes of post-natal mice resulted in malignant arrhythmias, heart failure, and premature death of these mice. In addition, heart growth impairment, aberrant metabolism relative gene expression, and increased cardiomyocyte apoptosis were observed in Rheb1-knockout mice prior to the development of heart failure and arrhythmias. Also, protein kinase B (PKB/Akt) signaling was enhanced in Rheb1-knockout mice, and removal of phosphatase and tensin homolog (Pten) significantly prolonged the survival of Rheb1-knockouts. Furthermore, signaling via the mammalian target of rapamycin complex 1 (mTORC1) was abolished and C/EBP homologous protein (CHOP) and phosphorylation levels of c-Jun N-terminal kinase (JNK) were increased in Rheb1 mutant mice. In conclusion, this study demonstrates that Rheb1 is important for maintaining cardiac function in post-natal mice via regulation of mTORC1 activity and stress on the endoplasmic reticulum. Moreover, activation of Akt signaling helps to improve the survival of mice with advanced heart failure. Thus, this study provides direct evidence that Rheb1 performs multiple important functions in the heart of the post-natal mouse. Enhancing Akt activity improves the survival of infant mice with advanced heart failure.
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MESH Headings
- Animals
- Animals, Newborn
- Apoptosis
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/pathology
- Cells, Cultured
- Endoplasmic Reticulum/metabolism
- Heart/growth & development
- Heart/physiopathology
- Heart Failure/etiology
- Heart Failure/metabolism
- Heart Failure/pathology
- JNK Mitogen-Activated Protein Kinases/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Monomeric GTP-Binding Proteins/deficiency
- Monomeric GTP-Binding Proteins/genetics
- Monomeric GTP-Binding Proteins/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Neuropeptides/deficiency
- Neuropeptides/genetics
- Neuropeptides/metabolism
- PTEN Phosphohydrolase/metabolism
- Phosphoric Monoester Hydrolases/metabolism
- Phosphorylation
- Proto-Oncogene Proteins c-akt/metabolism
- Ras Homolog Enriched in Brain Protein
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Affiliation(s)
- Yunshan Cao
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Lichan Tao
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Shutong Shen
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Junjie Xiao
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- Regeneration Lab and Experimental Center of Life sciences, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Hang Wu
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Beibei Li
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Xiangqi Wu
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Wen Luo
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Qi Xiao
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Xiaoshan Hu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Hailang Liu
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Junwei Nie
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Shuangshuang Lu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Baiyin Yuan
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
| | - Zhonglin Han
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
| | - Bo Xiao
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; E-Mail:
| | - Zhongzhou Yang
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061, China; E-Mails: (W.L.); (Q.X.); (X.H.); (J.N.); (S.L.); (B.Y.)
- Authors to whom correspondence should be addressed; E-Mails: or (X.L.); (Z.Y.); Tel.: +86-25-8371-4511-6325 (X.L.); Fax: +86-25-8367-3396 (X.L.)
| | - Xinli Li
- Department of Cardiology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; E-Mails: (Y.C.); (L.T.); (S.S.); (J.X.); (H.W.); (B.L.); (X.W.); (H.L.); (Z.H.)
- Authors to whom correspondence should be addressed; E-Mails: or (X.L.); (Z.Y.); Tel.: +86-25-8371-4511-6325 (X.L.); Fax: +86-25-8367-3396 (X.L.)
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12
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Zhang Z, Liu R, Townsend PA, Proud CG. p90RSKs mediate the activation of ribosomal RNA synthesis by the hypertrophic agonist phenylephrine in adult cardiomyocytes. J Mol Cell Cardiol 2013; 59:139-47. [DOI: 10.1016/j.yjmcc.2013.03.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 03/05/2013] [Accepted: 03/07/2013] [Indexed: 01/06/2023]
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13
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Tamai T, Yamaguchi O, Hikoso S, Takeda T, Taneike M, Oka T, Oyabu J, Murakawa T, Nakayama H, Uno Y, Horie K, Nishida K, Sonenberg N, Shah AM, Takeda J, Komuro I, Otsu K. Rheb (Ras homologue enriched in brain)-dependent mammalian target of rapamycin complex 1 (mTORC1) activation becomes indispensable for cardiac hypertrophic growth after early postnatal period. J Biol Chem 2013; 288:10176-10187. [PMID: 23426372 DOI: 10.1074/jbc.m112.423640] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cardiomyocytes proliferate during fetal life but lose their ability to proliferate soon after birth and further increases in cardiac mass are achieved through an increase in cell size or hypertrophy. Mammalian target of rapamycin complex 1 (mTORC1) is critical for cell growth and proliferation. Rheb (Ras homologue enriched in brain) is one of the most important upstream regulators of mTORC1. Here, we attempted to clarify the role of Rheb in the heart using cardiac-specific Rheb-deficient mice (Rheb(-/-)). Rheb(-/-) mice died from postnatal day 8 to 10. The heart-to-body weight ratio, an index of cardiomyocyte hypertrophy, in Rheb(-/-) was lower than that in the control (Rheb(+/+)) at postnatal day 8. The cell surface area of cardiomyocytes isolated from the mouse hearts increased from postnatal days 5 to 8 in Rheb(+/+) mice but not in Rheb(-/-) mice. Ultrastructural analysis indicated that sarcomere maturation was impaired in Rheb(-/-) hearts during the neonatal period. Rheb(-/-) hearts exhibited no difference in the phosphorylation level of S6 or 4E-BP1, downstream of mTORC1 at postnatal day 3 but showed attenuation at postnatal day 5 or 8 compared with the control. Polysome analysis revealed that the mRNA translation activity decreased in Rheb(-/-) hearts at postnatal day 8. Furthermore, ablation of eukaryotic initiation factor 4E-binding protein 1 in Rheb(-/-) mice improved mRNA translation, cardiac hypertrophic growth, sarcomere maturation, and survival. Thus, Rheb-dependent mTORC1 activation becomes essential for cardiomyocyte hypertrophic growth after early postnatal period.
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Affiliation(s)
- Takahito Tamai
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Osamu Yamaguchi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Shungo Hikoso
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Toshihiro Takeda
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Manabu Taneike
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan; Cardiovascular Division, King's College London British Heart Foundation Centre, London SE5 9NU, United Kingdom
| | - Takafumi Oka
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Jota Oyabu
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Tomokazu Murakawa
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hiroyuki Nakayama
- Department of Clinical Pharmacology and Pharmacogenomics, Graduate School of Pharmaceutical Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yoshihiro Uno
- Laboratory of Reproductive Engineering, The Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kyoji Horie
- Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kazuhiko Nishida
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan; Cardiovascular Division, King's College London British Heart Foundation Centre, London SE5 9NU, United Kingdom
| | - Nahum Sonenberg
- Department of Biochemistry and McGill Cancer Centre, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Ajay M Shah
- Cardiovascular Division, King's College London British Heart Foundation Centre, London SE5 9NU, United Kingdom
| | - Junji Takeda
- Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Issei Komuro
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kinya Otsu
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan; Cardiovascular Division, King's College London British Heart Foundation Centre, London SE5 9NU, United Kingdom.
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14
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Maillet M, van Berlo JH, Molkentin JD. Molecular basis of physiological heart growth: fundamental concepts and new players. Nat Rev Mol Cell Biol 2013; 14:38-48. [PMID: 23258295 PMCID: PMC4416212 DOI: 10.1038/nrm3495] [Citation(s) in RCA: 380] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The heart hypertrophies in response to developmental signals as well as increased workload. Although adult-onset hypertrophy can ultimately lead to disease, cardiac hypertrophy is not necessarily maladaptive and can even be beneficial. Progress has been made in our understanding of the structural and molecular characteristics of physiological cardiac hypertrophy, as well as of the endocrine effectors and associated signalling pathways that regulate it. Physiological hypertrophy is initiated by finite signals, which include growth hormones (such as thyroid hormone, insulin, insulin-like growth factor 1 and vascular endothelial growth factor) and mechanical forces that converge on a limited number of intracellular signalling pathways (such as PI3K, AKT, AMP-activated protein kinase and mTOR) to affect gene transcription, protein translation and metabolism. Harnessing adaptive signalling mediators to reinvigorate the diseased heart could have important medical ramifications.
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Affiliation(s)
- Marjorie Maillet
- Department of Pediatrics, University of Cincinnati, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
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15
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Function-based discovery of significant transcriptional temporal patterns in insulin stimulated muscle cells. PLoS One 2012; 7:e32391. [PMID: 22396763 PMCID: PMC3291562 DOI: 10.1371/journal.pone.0032391] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 01/30/2012] [Indexed: 11/23/2022] Open
Abstract
Background Insulin action on protein synthesis (translation of transcripts) and post-translational modifications, especially of those involving the reversible modifications such as phosphorylation of various signaling proteins, are extensively studied but insulin effect on transcription of genes, especially of transcriptional temporal patterns remains to be fully defined. Methodology/Principal Findings To identify significant transcriptional temporal patterns we utilized primary differentiated rat skeletal muscle myotubes which were treated with insulin and samples were collected every 20 min for 8 hours. Pooled samples at every hour were analyzed by gene array approach to measure transcript levels. The patterns of transcript levels were analyzed based on a novel method that integrates selection, clustering, and functional annotation to find the main temporal patterns associated to functional groups of differentially expressed genes. 326 genes were found to be differentially expressed in response to in vitro insulin administration in skeletal muscle myotubes. Approximately 20% of the genes that were differentially expressed were identified as belonging to the insulin signaling pathway. Characteristic transcriptional temporal patterns include: (a) a slow and gradual decrease in gene expression, (b) a gradual increase in gene expression reaching a peak at about 5 hours and then reaching a plateau or an initial decrease and other different variable pattern of increase in gene expression over time. Conclusion/Significance The new method allows identifying characteristic dynamic responses to insulin stimulus, common to a number of genes and associated to the same functional group. The results demonstrate that insulin treatment elicited different clusters of gene transcript profile supporting a temporal regulation of gene expression by insulin in skeletal muscle cells.
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16
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Zhou H, Huang S. The complexes of mammalian target of rapamycin. Curr Protein Pept Sci 2011; 11:409-24. [PMID: 20491627 DOI: 10.2174/138920310791824093] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Accepted: 05/20/2010] [Indexed: 02/07/2023]
Abstract
The mammalian target of rapamycin (mTOR) has attracted substantial attention because of its involvement in a variety of diseases, such as cancer, cardiac hypertrophy, diabetes and obesity. Current knowledge indicates that mTOR functions as two distinct multiprotein complexes, mTORC1 and mTORC2. mTORC1 phosphorylates p70 S6 kinase (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), and regulates cell growth, proliferation, and survival by integrating hormones, growth factors, nutrients, stressors and energy signals. In contrast, mTORC2 is insensitive to nutrients or energy conditions. However, in response to hormones or growth factors, mTORC2 phosphorylates Akt, and regulates actin cytoskeleton and cell survival. These findings not only reveal the crucial role of mTOR in physiology and pathology, but also reflect the complexity of the mTOR signaling network. In this review, we discuss the advances in studies of the mTOR complexes, including the interacting proteins, the upstream regulators and the downstream effectors of mTOR complexes, as well as their implication in certain human diseases.
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Affiliation(s)
- Hongyu Zhou
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA
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17
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Abstract
Ras homolog enriched in brain (Rheb) couples growth factor signaling to activation of the target of rapamycin complex 1 (TORC1). To study its role in mammals, we generated a Rheb knockout mouse. In contrast to mTOR or regulatory-associated protein of mTOR (Raptor) mutants, the inner cell mass of Rheb(-/-) embryos differentiated normally. Nevertheless, Rheb(-/-) embryos died around midgestation, most likely due to impaired development of the cardiovascular system. Rheb(-/-) embryonic fibroblasts showed decreased TORC1 activity, were smaller, and showed impaired proliferation. Rheb heterozygosity extended the life span of tuberous sclerosis complex 1-deficient (Tsc1(-/-)) embryos, indicating that there is a genetic interaction between the Tsc1 and Rheb genes in mouse.
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18
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Abstract
Tumor cell migration is a key step in the formation of cancer metastasis. The mammalian target of rapamycin (mTOR), a highly conserved and ubiquitously expressed serinethreonine kinase, has been intensely studied for over a decade as a central regulator of cell growth, proliferation, differentiation, and survival. Recent data have shown that mTOR also plays a critical role in the regulation of tumor cell motility and cancer metastasis. Here, we briefly review recent advances regarding mTOR signaling in tumor cell motility. We also discuss recent findings about the mechanism by which rapamycin, a specific inhibitor of mTOR, inhibits cell motility in vitro and metastasis in vivo.
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Affiliation(s)
- Hongyu Zhou
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA
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19
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Huang BPH, Wang Y, Wang X, Wang Z, Proud CG. Blocking eukaryotic initiation factor 4F complex formation does not inhibit the mTORC1-dependent activation of protein synthesis in cardiomyocytes. Am J Physiol Heart Circ Physiol 2009; 296:H505-14. [DOI: 10.1152/ajpheart.01105.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Activation of the mammalian target of rapamycin complex 1 (mTORC1) causes the dissociation of eukaryotic initiation factor 4E complex (eIF4E)-binding protein 1 (4E-BP1) from eIF4E, leading to increased eIF4F complex formation. mTORC1 positively regulates protein synthesis and is implicated in several diseases including cardiac hypertrophy, a potentially fatal disorder involving increased cardiomyocyte size. The importance of 4E-BP1 in mTORC1-regulated protein synthesis was investigated by overexpressing 4E-BP1, which blocks eIF4F formation in isolated primary cardiomyocytes without affecting other targets for mTORC1 signaling. Interestingly, blocking eIF4F formation did not impair the degree of activation of overall protein synthesis by the hypertrophic agent phenylephrine (PE), which, furthermore, remained dependent on mTORC1. Overexpressing 4E-BP1 also only had a small effect on PE-induced cardiomyocyte growth. Overexpressing 4E-BP1 did diminish the PE-stimulated synthesis of luciferase encoded by structured mRNAs, confirming that such mRNAs do require eIF4F for their translation in cardiomyocytes. These data imply that the substantial inhibition of cardiomyocyte protein synthesis and growth caused by inhibiting mTORC1 cannot be attributed to the activation of 4E-BP1 or loss of eIF4F complexes. Our data indicate that increased eIF4F formation plays, at most, only a minor role in the mTORC1-dependent activation of overall protein synthesis in these primary cells but is required for the translation of structured mRNAs. Therefore, other mTORC1 targets are more important in the inhibition by rapamycin of the rapid activation of protein synthesis and of cell growth.
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