1
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Pujalte-Martin M, Belaïd A, Bost S, Kahi M, Peraldi P, Rouleau M, Mazure NM, Bost F. Targeting cancer and immune cell metabolism with the complex I inhibitors metformin and IACS-010759. Mol Oncol 2024. [PMID: 38214418 DOI: 10.1002/1878-0261.13583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/15/2023] [Accepted: 12/29/2023] [Indexed: 01/13/2024] Open
Abstract
Metformin and IACS-010759 are two distinct antimetabolic agents. Metformin, an established antidiabetic drug, mildly inhibits mitochondrial complex I, while IACS-010759 is a new potent mitochondrial complex I inhibitor. Mitochondria is pivotal in the energy metabolism of cells by providing adenosine triphosphate through oxidative phosphorylation (OXPHOS). Hence, mitochondrial metabolism and OXPHOS become a vulnerability when targeted in cancer cells. Both drugs have promising antitumoral effects in diverse cancers, supported by preclinical in vitro and in vivo studies. We present evidence of their direct impact on cancer cells and their immunomodulatory effects. In clinical studies, while observational epidemiologic studies on metformin were encouraging, actual trial results were not as expected. However, IACS-01075 exhibited major adverse effects, thereby causing a metabolic shift to glycolysis and elevated lactic acid concentrations. Therefore, the future outlook for these two drugs depends on preventive clinical trials for metformin and investigations into the plausible toxic effects on normal cells for IACS-01075.
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Affiliation(s)
- Marc Pujalte-Martin
- Inserm U1065, Centre Méditerranéen de Médecine Moléculaire (C3M), Nice, France
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Amine Belaïd
- Inserm U1065, Centre Méditerranéen de Médecine Moléculaire (C3M), Nice, France
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Simon Bost
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Michel Kahi
- Inserm U1065, Centre Méditerranéen de Médecine Moléculaire (C3M), Nice, France
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Pascal Peraldi
- Inserm U1065, Centre Méditerranéen de Médecine Moléculaire (C3M), Nice, France
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Matthieu Rouleau
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
- CNRS UMR7370, LP2M, Nice, France
| | - Nathalie M Mazure
- Inserm U1065, Centre Méditerranéen de Médecine Moléculaire (C3M), Nice, France
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Frédéric Bost
- Inserm U1065, Centre Méditerranéen de Médecine Moléculaire (C3M), Nice, France
- Equipe Labellisée Ligue Nationale Contre le Cancer
- Faculté de Médecine, Université Côte d'Azur, Nice, France
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2
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Peraldi P, Loubat A, Chignon-Sicard B, Dani C, Ladoux A. Identification of Human Breast Adipose Tissue Progenitors Displaying Distinct Differentiation Potentials and Interactions with Cancer Cells. Biomedicines 2022; 10:biomedicines10081928. [PMID: 36009475 PMCID: PMC9406003 DOI: 10.3390/biomedicines10081928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/26/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
Breast adipose tissue (AT) participates in the physiological evolution and remodeling of the mammary gland due to its high plasticity. It is also a favorable microenvironment for breast cancer progression. However, information on the properties of human breast adipose progenitor cells (APCs) involved in breast physiology or pathology is scant. We performed differential enzymatic dissociation of human breast AT lobules. We isolated and characterized two populations of APCs. Here we report that these distinct breast APC populations selectively expressed markers suitable for characterization. The population preferentially expressing ALPL (MSCA1) showed higher adipogenic potential. The population expressing higher levels of INHBA and CD142 acquired myofibroblast characteristics upon TGF-β treatment and a myo-cancer-associated fibroblast profile in the presence of breast cancer cells. This population expressed the immune checkpoint CD274 (PD-L1) and facilitated the expansion of breast cancer mammospheres compared with the adipogenic population. Indeed, the breast, as with other fat depots, contains distinct types of APCs with differences in their ability to specialize. This indicates that they were differentially involved in breast remodeling. Their interactions with breast cancer cells revealed differences in the potential for tumor dissemination and estrogen receptor expression, and these differences might be relevant to improve therapies targeting the tumor microenvironment.
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Affiliation(s)
- Pascal Peraldi
- CNRS, INSERM, iBV, Université Côte d’Azur, 06107 Nice, France
| | - Agnès Loubat
- CNRS, INSERM, iBV, Université Côte d’Azur, 06107 Nice, France
| | - Bérengère Chignon-Sicard
- CNRS, INSERM, iBV, Université Côte d’Azur, 06107 Nice, France
- Department of Plastic and Reconstructive Surgery, Pasteur 2 Hospital, Université Côte d’Azur, 06107 Nice, France
| | - Christian Dani
- CNRS, INSERM, iBV, Université Côte d’Azur, 06107 Nice, France
| | - Annie Ladoux
- CNRS, INSERM, iBV, Université Côte d’Azur, 06107 Nice, France
- CNRS, Institute of Biology Valrose (iBV), University of Nice Sophia-Antipolis, 28 Avenue de Valombrose, CEDEX 2, 06107 Nice, France
- Correspondence:
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3
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Dumas K, Ayachi C, Gilleron J, Lacas‐Gervais S, Pastor F, Favier FB, Peraldi P, Vaillant N, Yvan‐Charvet L, Bonnafous S, Patouraux S, Anty R, Tran A, Gual P, Cormont M, Tanti J, Giorgetti‐Peraldi S. REDD1 deficiency protects against nonalcoholic hepatic steatosis induced by high‐fat diet. FASEB J 2020; 34:5046-5060. [DOI: 10.1096/fj.201901799rr] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 01/24/2020] [Accepted: 01/24/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Karine Dumas
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
| | - Chaima Ayachi
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
| | - Jerome Gilleron
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
| | | | - Faustine Pastor
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
| | | | - Pascal Peraldi
- Université Côte d’Azur, Inserm, CNRS, iBV, Team “Stem Cells and Differentiation” France
| | - Nathalie Vaillant
- Université Côte d’Azur, Inserm, C3M, Team “Haematometabolism in Diseases” France
| | - Laurent Yvan‐Charvet
- Université Côte d’Azur, Inserm, C3M, Team “Haematometabolism in Diseases” France
| | - Stéphanie Bonnafous
- Université Côte d’Azur, Inserm, C3M, Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
- Université Côte d’Azur, CHU, Inserm, C3M,Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
| | - Stéphanie Patouraux
- Université Côte d’Azur, Inserm, C3M, Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
- Université Côte d’Azur, CHU, Inserm, C3M,Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
| | - Rodolphe Anty
- Université Côte d’Azur, Inserm, C3M, Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
- Université Côte d’Azur, CHU, Inserm, C3M,Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
| | - Albert Tran
- Université Côte d’Azur, Inserm, C3M, Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
- Université Côte d’Azur, CHU, Inserm, C3M,Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
| | - Philippe Gual
- Université Côte d’Azur, Inserm, C3M, Team “Chronic Liver Diseases Associated with Steatosis and Alcohol” France
| | - Mireille Cormont
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
| | - Jean‐François Tanti
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
| | - Sophie Giorgetti‐Peraldi
- Université Côte d’Azur, Inserm, C3M, Team “Cellular and Molecular Physiopathology of Obesity” France
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4
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Arrighi N, Dani C, Peraldi P. [Adipose progenitors, myofibroblasts and fibrosis: is it all in the cilium?]. Med Sci (Paris) 2018; 34:524-526. [PMID: 30067208 DOI: 10.1051/medsci/20183406010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Nicole Arrighi
- Université Côte d'Azur, CNRS UMR7277, Inserm U1091, Institut de biologie de Valrose, 28, avenue de Valombrose, 06107 Nice Cedex 2, France
| | - Christian Dani
- Université Côte d'Azur, CNRS UMR7277, Inserm U1091, Institut de biologie de Valrose, 28, avenue de Valombrose, 06107 Nice Cedex 2, France
| | - Pascal Peraldi
- Université Côte d'Azur, CNRS UMR7277, Inserm U1091, Institut de biologie de Valrose, 28, avenue de Valombrose, 06107 Nice Cedex 2, France
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5
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Pastor F, Dumas K, Barthélémy MA, Regazzetti C, Druelle N, Peraldi P, Cormont M, Tanti JF, Giorgetti-Peraldi S. Implication of REDD1 in the activation of inflammatory pathways. Sci Rep 2017; 7:7023. [PMID: 28765650 PMCID: PMC5539207 DOI: 10.1038/s41598-017-07182-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/26/2017] [Indexed: 01/14/2023] Open
Abstract
In response to endotoxemia, the organism triggers an inflammatory response, and the visceral adipose tissue represents a major source of proinflammatory cytokines. The regulation of inflammation response in the adipose tissue is thus of crucial importance. We demonstrated that Regulated in development and DNA damage response-1 (REDD1) is involved in inflammation. REDD1 expression was increased in response to lipopolysaccharide (LPS) in bone marrow derived macrophages (BMDM) and in epidydimal adipose tissue. Loss of REDD1 protected the development of inflammation, since the expression of proinflammatory cytokines (TNFα, IL-6, IL-1β) was decreased in adipose tissue of REDD1−/− mice injected with LPS compared to wild-type mice. This decrease was associated with an inhibition of the activation of p38MAPK, JNK, NF-κB and NLRP3 inflammasome leading to a reduction of IL-1β secretion in response to LPS and ATP in REDD1−/− BMDM. Although REDD1 is an inhibitor of mTORC1, loss of REDD1 decreased inflammation independently of mTORC1 activation but more likely through oxidative stress regulation. Absence of REDD1 decreases ROS associated with a dysregulation of Nox-1 and GPx3 expression. Absence of REDD1 in macrophages decreases the development of insulin resistance in adipocyte-macrophage coculture. Altogether, REDD1 appears to be a key player in the control of inflammation.
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Affiliation(s)
- Faustine Pastor
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France
| | - Karine Dumas
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France
| | - Marie-Astrid Barthélémy
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France
| | - Claire Regazzetti
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France.,Université Nice Côte d'Azur, Inserm U1065, C3M, Team " Study of the melanocytic differentiation applied to vitiligo and melanoma: from the patient to the molecular mechanisms", Nice, France
| | - Noémie Druelle
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France.,Université Nice Côte d'Azur, Inserm U1091, CNRS U7277, iBV, Team Diabetes genetic team, Nice, France
| | - Pascal Peraldi
- Université Nice Côte d'Azur, Inserm U1091, CNRS U7277, iBV, Team "Stem cells and differentiation", Nice, France
| | - Mireille Cormont
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France
| | - Jean-François Tanti
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France
| | - Sophie Giorgetti-Peraldi
- Université Nice Côte d'Azur, Inserm U1065, C3M, Team Cellular and Molecular Physiopathology of Obesity, Nice, France.
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6
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Chignon-Sicard B, Kouidhi M, Yao X, Delerue-Audegond A, Villageois P, Peraldi P, Ferrari P, Rival Y, Piwnica D, Aubert J, Dani C. Platelet-rich plasma respectively reduces and promotes adipogenic and myofibroblastic differentiation of human adipose-derived stromal cells via the TGFβ signalling pathway. Sci Rep 2017; 7:2954. [PMID: 28592806 PMCID: PMC5462784 DOI: 10.1038/s41598-017-03113-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/24/2017] [Indexed: 11/09/2022] Open
Abstract
Autologous fat grafting is a gold standard therapy for soft tissue defects, but is hampered by unpredictable postoperative outcomes. Fat graft enrichment with adipose-derived stromal cell (ASCs) was recently reported to enhance graft survival. Platelet-rich plasma (PRP) has also emerged as a biologic scaffold that promotes fat graft viability. Combined ASC/PRP fat grafting enrichment is thus a promising new regenerative medicine approach. The effects of PRP on ASC proliferation are well documented, but the impact of PRP on ASC differentiation has yet to be investigated in depth to further elucidate the PRP clinical effects. Here we analyzed the human ASC fate upon PRP treatment. PRP was found to sharply reduce the potential of ASCs to undergo differentiation into adipocytes. Interestingly, the PRP anti-adipogenic effect was accompanied by the generation of myofibroblast-like cells. Among the various factors released from PRP, TGFβ pathway activators played a critical role in both the anti-adipogenic and pro-myofibroblastic PRP effects. Overall, these data suggest that PRP participates in maintaining a pool of ASCs and in the repair process by promoting ASC differentiation into myofibroblast-like cells. TGFβ may provide an important target pathway to improve PRP clinical outcomes.
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Affiliation(s)
- Bérengère Chignon-Sicard
- Université Côte d'Azur, CNRS, Inserm, iBV, Faculté de Médecine, 06107, Nice Cedex 2, France.,Plastic, Reconstructive and Hand Surgery Department, Hôpital Pasteur 2, Nice, France
| | - Magali Kouidhi
- Université Côte d'Azur, CNRS, Inserm, iBV, Faculté de Médecine, 06107, Nice Cedex 2, France
| | - Xi Yao
- Université Côte d'Azur, CNRS, Inserm, iBV, Faculté de Médecine, 06107, Nice Cedex 2, France
| | | | - Phi Villageois
- Université Côte d'Azur, CNRS, Inserm, iBV, Faculté de Médecine, 06107, Nice Cedex 2, France
| | - Pascal Peraldi
- Université Côte d'Azur, CNRS, Inserm, iBV, Faculté de Médecine, 06107, Nice Cedex 2, France
| | | | - Yves Rival
- Research Galderma, Sophia, Antipolis, France
| | | | | | - Christian Dani
- Université Côte d'Azur, CNRS, Inserm, iBV, Faculté de Médecine, 06107, Nice Cedex 2, France.
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7
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Hafner AL, Contet J, Ravaud C, Yao X, Villageois P, Suknuntha K, Annab K, Peraldi P, Binetruy B, Slukvin II, Ladoux A, Dani C. Brown-like adipose progenitors derived from human induced pluripotent stem cells: Identification of critical pathways governing their adipogenic capacity. Sci Rep 2016; 6:32490. [PMID: 27577850 PMCID: PMC5006163 DOI: 10.1038/srep32490] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/08/2016] [Indexed: 12/19/2022] Open
Abstract
Human induced pluripotent stem cells (hiPSCs) show great promise for obesity treatment as they represent an unlimited source of brown/brite adipose progenitors (BAPs). However, hiPSC-BAPs display a low adipogenic capacity compared to adult-BAPs when maintained in a traditional adipogenic cocktail. The reasons of this feature are unknown and hamper their use both in cell-based therapy and basic research. Here we show that treatment with TGFβ pathway inhibitor SB431542 together with ascorbic acid and EGF were required to promote hiPSCs-BAP differentiation at a level similar to adult-BAP differentiation. hiPSC-BAPs expressed the molecular identity of adult-UCP1 expressing cells (PAX3, CIDEA, DIO2) with both brown (ZIC1) and brite (CD137) adipocyte markers. Altogether, these data highlighted the critical role of TGFβ pathway in switching off hiPSC-brown adipogenesis and revealed novel factors to unlock their differentiation. As hiPSC-BAPs display similarities with adult-BAPs, it opens new opportunities to develop alternative strategies to counteract obesity.
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Affiliation(s)
| | - Julian Contet
- Université Côte d’Azur, CNRS, Inserm, iBV, Nice, France
| | | | - Xi Yao
- Université Côte d’Azur, CNRS, Inserm, iBV, Nice, France
| | | | - Kran Suknuntha
- Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53715, USA
| | - Karima Annab
- Inserm U910, Faculty of Medicine La Timone, Marseille, France
| | | | | | - Igor I. Slukvin
- Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53715, USA
| | - Annie Ladoux
- Université Côte d’Azur, CNRS, Inserm, iBV, Nice, France
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8
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Forcioli-Conti N, Estève D, Bouloumié A, Dani C, Peraldi P. The size of the primary cilium and acetylated tubulin are modulated during adipocyte differentiation: Analysis of HDAC6 functions in these processes. Biochimie 2016; 124:112-123. [DOI: 10.1016/j.biochi.2015.09.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 09/07/2015] [Indexed: 01/08/2023]
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9
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Arrighi N, Moratal C, Clément N, Giorgetti-Peraldi S, Peraldi P, Loubat A, Kurzenne JY, Dani C, Chopard A, Dechesne CA. Characterization of adipocytes derived from fibro/adipogenic progenitors resident in human skeletal muscle. Cell Death Dis 2015; 6:e1733. [PMID: 25906156 PMCID: PMC4650547 DOI: 10.1038/cddis.2015.79] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/16/2015] [Accepted: 02/18/2015] [Indexed: 01/09/2023]
Abstract
A population of fibro/adipogenic but non-myogenic progenitors located between skeletal muscle fibers was recently discovered. The aim of this study was to determine the extent to which these progenitors differentiate into fully functional adipocytes. The characterization of muscle progenitor-derived adipocytes is a central issue in understanding muscle homeostasis. They are considered as being the cellular origin of intermuscular adipose tissue that develops in several pathophysiological situations. Here fibro/adipogenic progenitors were isolated from a panel of 15 human muscle biopsies on the basis of the specific cell-surface immunophenotype CD15+/PDGFRα+CD56−. This allowed investigations of their differentiation into adipocytes and the cellular functions of terminally differentiated adipocytes. Adipogenic differentiation was found to be regulated by the same effectors as those regulating differentiation of progenitors derived from white subcutaneous adipose tissue. Similarly, basic adipocyte functions, such as triglyceride synthesis and lipolysis occurred at levels similar to those observed with subcutaneous adipose tissue progenitor-derived adipocytes. However, muscle progenitor-derived adipocytes were found to be insensitive to insulin-induced glucose uptake, in association with the impairment of phosphorylation of key insulin-signaling effectors. Our findings indicate that muscle adipogenic progenitors give rise to bona fide white adipocytes that have the unexpected feature of being insulin-resistant.
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Affiliation(s)
- N Arrighi
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
| | - C Moratal
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
| | - N Clément
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
| | - S Giorgetti-Peraldi
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of Obesity and Diabetes, Nice, France
| | - P Peraldi
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
| | - A Loubat
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
| | - J-Y Kurzenne
- Hôpitaux Pédiatriques de Nice CHU-Lenval, Nice, France
| | - C Dani
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
| | - A Chopard
- UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France
| | - C A Dechesne
- 1] UFR Sciences, Université Nice Sophia Antipolis, Nice F-06108, France [2] CNRS, UMR7277, F-06108 Nice, France [3] INSERM U1091, F-06108 Nice, France
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10
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Regazzetti C, Dumas K, Lacas-Gervais S, Pastor F, Peraldi P, Bonnafous S, Dugail I, Le Lay S, Valet P, Le Marchand-Brustel Y, Tran A, Gual P, Tanti JF, Cormont M, Giorgetti-Peraldi S. Hypoxia inhibits Cavin-1 and Cavin-2 expression and down-regulates caveolae in adipocytes. Endocrinology 2015; 156:789-801. [PMID: 25521582 DOI: 10.1210/en.2014-1656] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
During obesity, a hypoxic state develops within the adipose tissue, resulting in insulin resistance. To understand the underlying mechanism, we analyzed the involvement of caveolae because they play a crucial role in the activation of insulin receptors. In the present study, we demonstrate that in 3T3-L1 adipocytes, hypoxia induces the disappearance of caveolae and inhibits the expression of Cavin-1 and Cavin-2, two proteins necessary for the formation of caveolae. In mice, hypoxia induced by the ligature of the spermatic artery results in the decrease of cavin-1 and cavin-2 expression in the epididymal adipose tissue. Down-regulation of the expression of cavins in response to hypoxia is dependent on hypoxia-inducible factor-1. Indeed, the inhibition of hypoxia-inducible factor-1 restores the expression of cavins and caveolae formation. Expression of cavins regulates insulin signaling because the silencing of cavin-1 and cavin-2 impairs insulin signaling pathway. In human, cavin-1 and cavin-2 are decreased in the sc adipose tissue of obese diabetic patients compared with lean subjects. Moreover, the expression of cavin-2 correlates negatively with the homeostatic model assessment index of insulin resistance and glycated hemoglobin level. In conclusion, we propose a new mechanism in which hypoxia inhibits cavin-1 and cavin-2 expression, resulting in the disappearance of caveolae. This leads to the inhibition of insulin signaling and the establishment of insulin resistance.
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Affiliation(s)
- Claire Regazzetti
- INSERM Unité 1065 (C.R., K.D., F.P., Y.L.M.-B., J.-F.T., M.C., S.G.-P.), C3M, Mediterranean Research Centre for Molecular Medicine, Team 7 (Cellular and Molecular Physiopathology of Obesity and Diabetes), Unité de Formation et de Recherche (UFR) Medicine (C.R., K.D., F.P., P.P., S.B., Y.L.M.-B., A.T., P.G., J.-F.T., M.C., S.G.-P.), and INSERM Unité 1065 (S.B., A.T., P.G.), C3M, Mediterranean Research Centre for Molecular Medicine, Team 8 (Hepatic Complications in Obesity),University of Nice, Sophia Antipolis F-06204 Nice, France; Centre Commun de Microscopie Appliquée (S.L.-G.), University of Nice, Sophia Antipolis, UFR Sciences, Parc Valrose, F-06108 Nice, France; Unité Mixte de Recherche Centre National de la Recherche Scientifique 7277 (P.P.), Unité Mixte de Recherche INSERM Unité 1091, UFR Medicine, F-06107 Nice, France; Centre Hospitalier Universitaire de Nice, Digestive Center (S.B., A.T.), Nice F-06202, Cedex 3, France; INSERM Unité Mixte de Recherche S872 (I.D.), Centre de Recherche des Cordeliers, Eq8, F-75006 Paris, France; INSERM Unité 1063 (S.L.L.), Stress Oxydant et Pathologies Métaboliques, Institut de Biologie en Santé, F-49933 Angers, France; and INSERM Unité Mixte de Recherche 1048 (P.V.), Institut des Maladies Métaboliques et Cardiovasculaires, Université Paul Sabatier, F-31432 Toulouse, France
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11
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Regazzetti C, Dumas K, Le Marchand-Brustel Y, Peraldi P, Tanti JF, Giorgetti-Peraldi S. Regulated in development and DNA damage responses -1 (REDD1) protein contributes to insulin signaling pathway in adipocytes. PLoS One 2012; 7:e52154. [PMID: 23272222 PMCID: PMC3525563 DOI: 10.1371/journal.pone.0052154] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 11/08/2012] [Indexed: 01/17/2023] Open
Abstract
REDD1 (Regulated in development and DNA damage response 1) is a hypoxia and stress response gene and is a negative regulator of mTORC1. Since mTORC1 is involved in the negative feedback loop of insulin signaling, we have studied the role of REDD1 on insulin signaling pathway and its regulation by insulin. In human and murine adipocytes, insulin transiently stimulates REDD1 expression through a MEK dependent pathway. In HEK-293 cells, expression of a constitutive active form of MEK stabilizes REDD1 and protects REDD1 from proteasomal degradation mediated by CUL4A-DDB1 ubiquitin ligase complex. In 3T3-L1 adipocytes, silencing of REDD1 with siRNA induces an increase of mTORC1 activity as well as an inhibition of insulin signaling pathway and lipogenesis. Rapamycin, a mTORC1 inhibitor, restores the insulin signaling after downregulation of REDD1 expression. This observation suggests that REDD1 positively regulates insulin signaling through the inhibition of mTORC1 activity. In conclusion, our results demonstrate that insulin increases REDD1 expression, and that REDD1 participates in the biological response to insulin.
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Affiliation(s)
- Claire Regazzetti
- INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of obesity and diabetes, Nice, France
- University of Nice Sophia Antipolis, UFR Medicine, Nice, France
| | - Karine Dumas
- INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of obesity and diabetes, Nice, France
- University of Nice Sophia Antipolis, UFR Medicine, Nice, France
| | - Yannick Le Marchand-Brustel
- INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of obesity and diabetes, Nice, France
- University of Nice Sophia Antipolis, UFR Medicine, Nice, France
| | - Pascal Peraldi
- University of Nice Sophia Antipolis, UFR Medicine, Nice, France
- UMR CNRS 7277, UMR INSERM 1091, Faculty of Medicine, Nice, France
| | - Jean-François Tanti
- INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of obesity and diabetes, Nice, France
- University of Nice Sophia Antipolis, UFR Medicine, Nice, France
| | - Sophie Giorgetti-Peraldi
- INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of obesity and diabetes, Nice, France
- University of Nice Sophia Antipolis, UFR Medicine, Nice, France
- * E-mail:
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Villageois P, Wdziekonski B, Zaragosi LE, Plaisant M, Mohsen-Kanson T, Lay N, Ladoux A, Peraldi P, Dani C. Regulators of human adipose-derived stem cell self-renewal. Am J Stem Cells 2011; 1:42-47. [PMID: 23671796 PMCID: PMC3643382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 08/11/2011] [Indexed: 06/02/2023]
Abstract
Adipose tissue is an alternative source of mesenchymal stem cells and human adipose-derived stem cells (ASCs) display an attractive and substantial therapeutic potential when transplanted in animal models. To this end, an understanding of ASC biology is necessary and the knowledge of mechanisms that maintain ASCs in an undifferentiated state with no loss of differentiation potential during ex vivo expansion represents a crucial step. However, these mechanisms remain to be identified because appropriate human cellular models are scant. In this review we will describe a cellular model isolated from human adipose tissue displaying all the features of stem cells. Then, we will focus on the identification of intrinsic and extrinsic factors regulating the balance between human ASC proliferation and differentiation. We will point out the role of factors secreted by undifferentiated ASCs, such a FGF2, activin A, BMP4, Hedgehog molecules and secreted by adipose tissue macrophages. Finally, we will outline the role of miRNAs in these processes.
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Affiliation(s)
- Phi Villageois
- Université de Nice Sophia-Antipolis, Institut Biologie du Développement et Cancer, CNRS UMR 6543, Faculté de Médecine 28 avenue de Valombrose, 06108 Nice Cedex 2, France
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13
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Plaisant M, Giorgetti-Peraldi S, Gabrielson M, Loubat A, Dani C, Peraldi P. Inhibition of hedgehog signaling decreases proliferation and clonogenicity of human mesenchymal stem cells. PLoS One 2011; 6:e16798. [PMID: 21304817 PMCID: PMC3033417 DOI: 10.1371/journal.pone.0016798] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 01/11/2011] [Indexed: 01/23/2023] Open
Abstract
Human mesenchymal stem cells (hMSC) have the ability to differentiate into osteoblasts, adipocytes and chondrocytes. We have previously shown that hMSC were endowed with a basal level of Hedgehog signaling that decreased after differentiation of these cells. Since hMSC differentiation is associated with growth-arrest we investigated the function of Hh signaling on cell proliferation. Here, we show that inhibition of Hh signaling, using the classical inhibitor cyclopamine, or a siRNA directed against Gli-2, leads to a decrease in hMSC proliferation. This phenomenon is not linked to apoptosis but to a block of the cells in the G0/G1 phases of the cell cycle. At the molecular level, it is associated with an increase in the active form of pRB, and a decrease in cyclin A expression and MAP kinase phosphorylation. Inhibition of Hh signaling is also associated with a decrease in the ability of the cells to form clones. By contrast, inhibition of Hh signaling during hMSC proliferation does not affect their ability to differentiate. This study demonstrates that hMSC are endowed with a basal Hedgehog signaling activity that is necessary for efficient proliferation and clonogenicity of hMSC. This observation unravels an unexpected new function for Hedgehog signaling in the regulation of human mesenchymal stem cells and highlights the critical function of this morphogen in hMSC biology.
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Affiliation(s)
- Magali Plaisant
- CNRS UMR6543, Institute of Biology, Development and Cancer, Faculté de Médecine, Nice, France
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14
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Plaisant M, Fontaine C, Cousin W, Rochet N, Dani C, Peraldi P. Activation of hedgehog signaling inhibits osteoblast differentiation of human mesenchymal stem cells. Stem Cells 2009; 27:703-13. [PMID: 19096040 DOI: 10.1634/stemcells.2008-0888] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mesenchymal stem cells within the bone are responsible for the generation of osteoblasts, chondrocytes, and adipocytes. In rodents, Indian hedgehog has been shown to play a role in osteoblast differentiation. However, evidence for a direct function of hedgehog (Hh) in human osteoblastic differentiation is missing. Using different models of human mesenchymal stem cells we show that Hh signaling decreases during osteoblast differentiation. This is associated with a decrease in Smoothened expression, a key partner that triggers Hh signaling, and in the number of cells displaying a primary cilium, an organelle necessary for Hh signaling. Remarkably, treatment of human mesenchymal stem cells with sonic hedgehog or two molecules able to activate Hh signaling inhibits osteoblast differentiation. This inhibition is visualized through a decrease in mineralization and in the expression of osteoblastic genes. In particular, activation of Hh signaling induces a decrease in Runx2 expression, a key transcriptional factor controlling the early stage of osteoblast differentiation. Consistently, the activation of Hh signaling during the first days of differentiation is sufficient to inhibit osteoblast differentiation, whereas differentiated osteoblasts are not affected by Hh signaling. In summary, we show here, using various inducers of Hh signaling and mesenchymal stem cells of two different origins, that Hh signaling inhibits human osteoblast differentiation, in sharp contrast to what has been described in rodent cells. This species difference should be taken into account for screening for pro-osteogenic molecules.
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Affiliation(s)
- Magali Plaisant
- Institute of Signaling, Biology, Development and Cancer, Université de Nice Sophia-Antipolis, CNRS UMR, France
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15
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Peraldi P, Hotamisligil GS, Buurman WA, White M, Spiegelman BM. O-47: Mechanisms of TNF-α induced insulin resistance. Exp Clin Endocrinol Diabetes 2009. [DOI: 10.1055/s-0029-1211538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Djedaini M, Peraldi P, Drici MD, Darini C, Saint-Marc P, Dani C, Ladoux A. Lopinavir co-induces insulin resistance and ER stress in human adipocytes. Biochem Biophys Res Commun 2009; 386:96-100. [PMID: 19501568 DOI: 10.1016/j.bbrc.2009.05.148] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 05/29/2009] [Indexed: 10/20/2022]
Abstract
HIV-protease inhibitors (PIs) markedly decreased mortality of HIV-infected patients. However, their use has been associated with occurence of metabolic abnormalities the causes of which are not well understood. We report here that lopinavir, one of the most prescribed PI, dose-dependently co-induced insulin resistance and ER stress in human adipocytes obtained from differentiation of precursor cells. Insulin resistance was subsequent to IRS1 phosphorylation defects and resulted in a concentration-dependent decrease of glucose uptake. The major ER stress pathway involved was the phosphorylation of eIF2-alpha. Salubrinal, a selective eIF2-alpha dephosphorylation inhibitor, induced insulin resistance by targeting IRS1 phosphorylation at serine 312 and acted synergistically with LPV when both drugs were used in combination. This study points out the key role of eIF2-alpha phosphorylation in the development of PI-associated insulin resistance and ER stress. Thus, this protein represents a promising therapeutic target for development of new PIs devoid of adverse metabolic effects.
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Affiliation(s)
- Mansour Djedaini
- Institute of Biology Development and Cancer, University of Nice Sophia-Antipolis, CNRS, 28 Avenue de Valombrose, 06107 NICE Cedex2, France
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Regazzetti C, Peraldi P, Grémeaux T, Najem-Lendom R, Ben-Sahra I, Cormont M, Bost F, Le Marchand-Brustel Y, Tanti JF, Giorgetti-Peraldi S. Hypoxia decreases insulin signaling pathways in adipocytes. Diabetes 2009; 58:95-103. [PMID: 18984735 PMCID: PMC2606898 DOI: 10.2337/db08-0457] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Obesity is characterized by an overgrowth of adipose tissue that leads to the formation of hypoxic areas within this tissue. We investigated whether this phenomenon could be responsible for insulin resistance by studying the effect of hypoxia on the insulin signaling pathway in adipocytes. RESEARCH DESIGN AND METHODS The hypoxic signaling pathway was modulated in adipocytes from human and murine origins through incubation under hypoxic conditions (1% O(2)) or modulation of hypoxia-inducible factor (HIF) expression. Insulin signaling was monitored through the phosphorylation state of several key partners of the pathway and glucose transport. RESULTS In both human and murine adipocytes, hypoxia inhibits insulin signaling as revealed by a decrease in the phosphorylation of insulin receptor. In 3T3-L1 adipocytes, this inhibition of insulin receptor phosphorylation is followed by a decrease in the phosphorylation state of protein kinase B and AS160, as well as an inhibition of glucose transport in response to insulin. These processes were reversible under normoxic conditions. The mechanism of inhibition seems independent of protein tyrosine phosphatase activities. Overexpression of HIF-1alpha or -2alpha or activation of HIF transcription factor with CoCl(2) mimicked the effect of hypoxia on insulin signaling, whereas downregulation of HIF-1alpha and -2alpha by small interfering RNA inhibited it. CONCLUSIONS We have demonstrated that hypoxia creates a state of insulin resistance in adipocytes that is dependent upon HIF transcription factor expression. Hypoxia could be envisioned as a new mechanism that participates in insulin resistance in adipose tissue of obese patients.
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Affiliation(s)
- Claire Regazzetti
- Team Cellular and Molecular Physiopathology of Obesity and Diabetes, Institut National de la Santé et de la Recherche Médicale U 895, Mediterranean Research Centre for Molecular Medicine, Nice, France
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18
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Zaragosi LE, Wdziekonski B, Fontaine C, Villageois P, Peraldi P, Dani C. Effects of GSK3 inhibitors on in vitro expansion and differentiation of human adipose-derived stem cells into adipocytes. BMC Cell Biol 2008; 9:11. [PMID: 18271953 PMCID: PMC2257931 DOI: 10.1186/1471-2121-9-11] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Accepted: 02/13/2008] [Indexed: 01/08/2023] Open
Abstract
Background Multipotent stem cells exist within adipose tissue throughout life. An abnormal recruitment of these adipose precursor cells could participate to hyperplasia of adipose tissue observed in severe obesity or to hypoplasia of adipose tissue observed in lipodystrophy. Therefore, pharmacological molecules that control the pool of stem cells in adipose tissue are of great interest. Glycogen Synthase Kinase (GSK) 3 has been previously described as involved in differentiation of preadipose cells and might be a potential therapeutic target to modulate proliferation and differentiation of adipocyte precursors. However, the impact of GSK3 inhibition on human adipose-derived stem cells remained to be investigated. The aim of this study was to investigate GSK3 as a possible target for pharmacological inhibition of stem cell adipogenesis. To reach this goal, we studied the effects of pharmacological inhibitors of GSK3, i.e. lithium chloride (LiCl) and BIO on proliferation and adipocyte differentiation of multipotent stem cells derived from human adipose tissue. Results Our results showed that GSK3 inhibitors inhibited proliferation and clonogenicity of human stem cells, strongly suggesting that GSK3 inhibitors could be potent regulators of the pool of adipocyte precursors in adipose tissue. The impact of GSK3 inhibition on differentiation of hMADS cells was also investigated. Adipogenic and osteogenic differentiations were inhibited upon hMADS treatment with BIO. Whereas a chronic treatment was required to inhibit osteogenesis, a treatment that was strictly restricted to the early step of differentiation was sufficient to inhibit adipogenesis. Conclusion These results demonstrated the feasibility of a pharmacological approach to regulate adipose-derived stem cell function and that GSK3 could represent a potential target for controlling adipocyte precursor pool under conditions where fat tissue formation is impaired.
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Affiliation(s)
- Laure-Emmanuelle Zaragosi
- Institute of Signalling, Biology of Development and Cancer, University of Nice Sophia- Antipolis, CNRS 6543, 28 avenue Valrose, 06100 Nice, France.
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19
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Abstract
Human stem cells are powerful tools by which to investigate molecular mechanisms of cell growth and differentiation under normal and pathological conditions. Hedgehog signaling, the dysregulation of which causes several pathologies, such as congenital defects and cancer, is involved in several cell differentiation processes and interferes with adipocyte differentiation of rodent cells. The present study was aimed at investigating the effect of Hedgehog pathway modulation on adipocyte phenotype using different sources of human mesenchymal cells, such as bone marrow stromal cells and human multipotent adipose-derived stem cells. We bring evidence that Hedgehog signaling decreases during human adipocyte differentiation. Inhibition of this pathway is not sufficient to trigger adipogenesis, but activation of Hedgehog pathway alters adipocyte morphology as well as insulin sensitivity. Analysis of glycerol-3-phosphate dehydrogenase activity and expression of adipocyte marker genes indicate that activation of Hedgehog signaling by purmorphamine impairs adipogenesis. In sharp contrast to reports in rodent cells, the maturation process, but not the early steps of human mesenchymal stem cell differentiation, is affected by Hedgehog activation. Hedgehog interferes with adipocyte differentiation by targeting CCAAT enhancer-binding protein alpha and peroxisome proliferator-activated receptor (PPAR) gamma2 expression, whereas PPARgamma1 level remains unaffected. Although Hedgehog pathway stimulation does not modify the total number of adipocytes, adipogenesis appears dramatically impaired, with reduced lipid accumulation, a decrease in adipocyte-specific markers, and acquisition of an insulin-resistant phenotype. This study indicates that a decrease in Hedgehog signaling is necessary but not sufficient to trigger adipocyte differentiation and unveils a striking difference in the adipocyte differentiation process between rodent and human mesenchymal stem cells.
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Affiliation(s)
- Coralie Fontaine
- Institute of Signaling, Biology, Development and Cancer, Université de Nice Sophia-Antipolis, Centre National de la Recherche Scientifique UMR6543, Nice, France
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Abstract
Morphogenes, abundantly described during embryogenesis have recently emerged as crucial modulators of cell differentiation processes. Hedgehog signaling, the dysregulation of which causing several pathologies such as congenital defects and cancer, is involved in several cell differentiation processes including adipogenesis. This review presents an overview of the relations between Hedgehog signaling, adipocyte differentiation and fat mass. While the anti-adipogenic role of Hedgehog signaling seems to be established, the effect of Hedgehog inhibition on adipocyte differentiation in vitro remains debated. Finally, Hedgehog potential as a pharmacological target to treat fat mass disorders is discussed.
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Affiliation(s)
- Wendy Cousin
- ISBDC, Université De Nice Sophia-Antipolis, CNRS, 28 Avenue De Valrose, 06100 Nice, France.
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Cousin W, Dani C, Peraldi P. Inhibition of the anti-adipogenic Hedgehog signaling pathway by cyclopamine does not trigger adipocyte differentiation. Biochem Biophys Res Commun 2006; 349:799-803. [PMID: 16949046 DOI: 10.1016/j.bbrc.2006.08.112] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 08/17/2006] [Indexed: 01/24/2023]
Abstract
Dysregulation of Hedgehog signaling can lead to several pathologies such as congenital defects and cancer. Here, we show that Hedgehog signaling is active in undifferentiated 3T3-L1 cells and decreases during adipocyte differentiation. Interestingly, this is paralleled by a decrease in Indian Hedgehog expression. We then tested if this down-regulation was sufficient to induce adipocyte differentiation. To this end, we demonstrate that the well-characterized Hedgehog inhibitor cyclopamine induced a decrease in Hedgehog signaling, similar to the one observed during adipocyte differentiation. However, cyclopamine did not induce nor potentiate adipocyte differentiation, as monitored by triglyceride staining and by the expression of several adipocyte markers: aP2, adipsin, C/EBPalpha, and Pref-1. Moreover, cyclopamine cannot substitute for other components of the differentiation medium: insulin, dexamethasone or IBMX. These results indicate that although Hedgehog signaling decreases during adipocyte differentiation, this down-regulation is not sufficient to trigger adipocyte differentiation. This suggests that Hedgehog signaling is an inadequate pharmacological target for patient suffering from syndromes associated with a decrease in fat mass, such as the ones observed in lipodystrophies.
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Affiliation(s)
- W Cousin
- Institute of Signaling, Developmental Biology and Cancer CNRS UMR6543, Université de Nice Sophia-Antipolis, Stem Cells and Differentiation, Nice, France
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Emanuelli B, Glondu M, Filloux C, Peraldi P, Van Obberghen E. The potential role of SOCS-3 in the interleukin-1beta-induced desensitization of insulin signaling in pancreatic beta-cells. Diabetes 2004; 53 Suppl 3:S97-S103. [PMID: 15561930 DOI: 10.2337/diabetes.53.suppl_3.s97] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Defects in insulin secretion, resulting from loss of function or destruction of pancreatic beta-cells, trigger diabetes. Interleukin (IL)-1beta is a proinflammatory cytokine that is involved in type 1 and type 2 diabetes development and impairs beta-cell survival and function. Because effective insulin signaling is required for the optimal beta-cell function, we assessed the effect of IL-1beta on the insulin pathway in a rat pancreatic beta-cell line. We show that IL-1beta decreases insulin-induced tyrosine phosphorylation of the insulin receptor (IR) and insulin receptor substrate (IRS) proteins as well as phosphatidylinositol 3-kinase (PI3K) activation, and that this action is not due to the IL-1beta-dependent nitric oxide (NO) production in RINm5F cells. We next analyzed if suppressor of cytokine signaling (SOCS)-3, which can be induced by multiple cytokines and which we identified as an insulin action inhibitor, was implicated in the IL-1beta inhibitory effect on insulin signaling in these cells. We show that IL-1beta increases SOCS-3 expression and induces SOCS-3/IR complex formation in RINm5F cells. Moreover, we find that ectopically expressed SOCS-3 associates with the IR and reduces insulin-dependent IR autophosphorylation and IRS/PI3K pathway in a way comparable to IL-1beta treatment in RINm5F cells. We propose that IL-1beta decreases insulin action in beta-cells through the induction of SOCS-3 expression, and that this effect potentially alters insulin-induced beta-cell survival.
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Affiliation(s)
- Brice Emanuelli
- INSERM U145, IFR-50, Faculty of Medicine, 06107 Nice Cedex 2. France
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23
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Cousin W, Courseaux A, Ladoux A, Dani C, Peraldi P. Cloning of hOST-PTP: the only example of a protein-tyrosine-phosphatase the function of which has been lost between rodent and human. Biochem Biophys Res Commun 2004; 321:259-65. [PMID: 15358244 DOI: 10.1016/j.bbrc.2004.06.137] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Indexed: 11/28/2022]
Abstract
Protein-tyrosine-phosphatases (PTP-ases), in concert with protein tyrosine kinases, control various biological activities such as cell growth and differentiation. In rodents, around 40 PTP-ases have been described. Functional orthologue for each of these PTP-ases have been identified in human, except for OST-PTP. OST-PTP is a transmembrane PTP-ase with a restricted tissue distribution. In silico analysis on public sequence databases reveals a human OST-PTP gene orthologue that encompasses 21 kb on chromosome 1q32.1. Using RT-PCR we isolated a 4 kb hOST-PTP transcript. hOST-PTP cDNA sequence exhibits numerous disablements indicating that it does not code for a PTP-ase but is rather a pseudogene with unique features. Indeed, (i) it has no "functional" parent in the human genome, (ii) it has retained an "intron-exon" structure, and (iii) it is transcribed in a regulated manner. Interestingly, we found two ESTs, from domesticated pig and from cow that exhibit ORF that would predict a functional OST-PTP orthologue in Artiodactyls. Taken together, these results indicate that OST-PTP is the only PTP-ase the function of which has been lost during the evolution process between rodents and human.
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Affiliation(s)
- W Cousin
- Institute of Signaling Developmental Biology and Cancer-UMR 6543 CNRS, Faculté des Sciences, 06108 Nice Cedex 2, France
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Emanuelli B, Peraldi P, Filloux C, Chavey C, Freidinger K, Hilton DJ, Hotamisligil GS, Van Obberghen E. SOCS-3 inhibits insulin signaling and is up-regulated in response to tumor necrosis factor-alpha in the adipose tissue of obese mice. J Biol Chem 2001; 276:47944-9. [PMID: 11604392 DOI: 10.1074/jbc.m104602200] [Citation(s) in RCA: 327] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
SOCS (suppressor of cytokine signaling) proteins are inhibitors of cytokine signaling involved in negative feedback loops. We have recently shown that insulin increases SOCS-3 mRNA expression in 3T3-L1 adipocytes. When expressed, SOCS-3 binds to phosphorylated Tyr(960) of the insulin receptor and prevents Stat 5B activation by insulin. Here we show that in COS-7 cells SOCS-3 decreases insulin-induced insulin receptor substrate 1 (IRS-1) tyrosine phosphorylation and its association with p85, a regulatory subunit of phosphatidylinositol-3 kinase. This mechanism points to a function of SOCS-3 in insulin resistance. Interestingly, SOCS-3 expression was found to be increased in the adipose tissue of obese mice, but not in the liver and muscle of these animals. Two polypeptides known to be elevated during obesity, insulin and tumor necrosis factor-alpha (TNF-alpha), induce SOCS-3 mRNA expression in mice. Insulin induces a transient expression of SOCS-3 in the liver, muscle, and the white adipose tissue (WAT). Strikingly, TNF-alpha induced a sustained SOCS-3 expression, essentially in the WAT. Moreover, transgenic ob/ob mice lacking both TNF receptors have a pronounced decrease in SOCS-3 expression in the WAT compared with ob/ob mice, providing genetic evidence for a function of this cytokine in obesity-induced SOCS-3 expression. As SOCS-3 appears as a TNF-alpha target gene that is elevated during obesity, and as SOCS-3 antagonizes insulin-induced IRS-1 tyrosine phosphorylation, we suggest that it is a player in the development of insulin resistance.
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Affiliation(s)
- B Emanuelli
- INSERM U145, IFR 50, Faculté de Médecine, 06107 Nice cedex 2, France
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Van Obberghen E, Baron V, Delahaye L, Emanuelli B, Filippa N, Giorgetti-Peraldi S, Lebrun P, Mothe-Satney I, Peraldi P, Rocchi S, Sawka-Verhelle D, Tartare-Deckert S, Giudicelli J. Surfing the insulin signaling web. Eur J Clin Invest 2001; 31:966-77. [PMID: 11737239 DOI: 10.1046/j.1365-2362.2001.00896.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The diverse biological actions of insulin and insulin-like growth factor I (IGF-I) are initiated by binding of the polypeptides to their respective cell surface tyrosine kinase receptors. These activated receptors phosphorylate a series of endogenous substrates on tyrosine, amongst which the insulin receptor substrate (IRS) proteins are the best characterized. Their phosphotyrosine-containing motifs become binding sites for Src homology 2 (SH2) domains on proteins such as SH2 domain-containing protein-tyrosine-phosphatase (SHP)-2/Syp, growth factor receptor bound-2 protein, (Grb-2), and phosphatidyl inositol 3 kinase (PI3 kinase), which participate in activation of specific signaling cascades. However, the IRS molecules are not only platforms for signaling molecules, they also orchestrate the generation of signal specificity, integration of signals induced by several extracellular stimuli, and signal termination and modulation. An extensive review is beyond the scope of the present article, which will be centered on our own contribution and reflect our biases.
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Affiliation(s)
- E Van Obberghen
- Inserm U 145, IFR 50, Faculté de Médecine, Avenue de Valombrose, Nice Cedex, France.
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Peraldi P, Filloux C, Emanuelli B, Hilton DJ, Van Obberghen E. Insulin induces suppressor of cytokine signaling-3 tyrosine phosphorylation through janus-activated kinase. J Biol Chem 2001; 276:24614-20. [PMID: 11325969 DOI: 10.1074/jbc.m102209200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Suppressor of cytokine signaling (SOCS) proteins were originally described as cytokine-induced molecules involved in negative feedback loops. We have shown that SOCS-3 is also a component of the insulin signaling network (). Indeed, insulin leads to SOCS-3 expression in 3T3-L1 adipocytes. Once produced, SOCS-3 binds to phosphorylated tyrosine 960 of the insulin receptor and inhibits insulin signaling. Now we show that in 3T3-L1 adipocytes and in transfected COS-7 cells insulin leads to SOCS-3 tyrosine phosphorylation. This phosphorylation takes place on Tyr(204) and is dependent upon a functional SOCS-3 SH2 domain. Purified insulin receptor directly phosphorylates SOCS-3. However, in intact cells, a mutant of the insulin receptor, IRY960F, unable to bind SOCS-3, was as efficient as the wild type insulin receptor to phosphorylate SOCS-3. Importantly, IRY960F is as potent as the wild type insulin receptor to activate janus-activated kinase (Jak) 1 and Jak2. Furthermore, expression of a dominant negative form of Jak2 inhibits insulin-induced SOCS-3 tyrosine phosphorylation. As transfected Jaks have been shown to cause SOCS-3 phosphorylation, we propose that insulin induces SOCS-3 phosphorylation through Jak activation. Our data indicate that SOCS-3 belongs to a class of tyrosine-phosphorylated insulin signaling molecules, the phosphorylation of which is not dependent upon a direct coupling with the insulin receptor but relies on the Jaks.
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Affiliation(s)
- P Peraldi
- INSERM U145, IFR-50, Faculté de Médecine, 06107 Nice Cédex 2, France.
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Emanuelli B, Peraldi P, Filloux C, Sawka-Verhelle D, Hilton D, Van Obberghen E. SOCS-3 is an insulin-induced negative regulator of insulin signaling. J Biol Chem 2000; 275:15985-91. [PMID: 10821852 DOI: 10.1074/jbc.275.21.15985] [Citation(s) in RCA: 367] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The SOCS proteins are induced by several cytokines and are involved in negative feedback loops. Here we demonstrate that in 3T3-L1 adipocytes, insulin, a hormone whose receptor does not belong to the cytokine receptor family, induces SOCS-3 expression but not CIS or SOCS-2. Using transfection of COS-7 cells, we show that insulin induction of SOCS-3 is enhanced upon Stat5B expression. Moreover, Stat5B from insulin-stimulated cells binds directly to a Stat element present in the SOCS-3 promoter. Once induced, SOCS-3 inhibits insulin activation of Stat5B without modifying the insulin receptor tyrosine kinase activity. Two pieces of evidence suggest that this negative regulation likely results from competition between SOCS-3 and Stat5B binding to the same insulin receptor motif. First, using a yeast two-hybrid system, we show that SOCS-3 binds to the insulin receptor at phosphotyrosine 960, which is precisely where Stat5B binds. Second, using confocal microscopy, we show that insulin induces translocation of SOCS-3 from an intracellular compartment to the cell membrane, leading to colocalization of SOCS-3 with the insulin receptor. This colocalization is dependent upon phosphorylation of insulin receptor tyrosine 960. Indeed, in cells expressing an insulin receptor mutant in which tyrosine 960 has been mutated to phenylalanine, insulin does not modify the cellular localization of SOCS-3. We have thus revealed an insulin target gene of which the expression is potentiated upon Stat5B activation. By inhibiting insulin-stimulated Stat5B, SOCS-3 appears to function as a negative regulator of insulin signaling.
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Affiliation(s)
- B Emanuelli
- INSERM U145, IFR-50, Faculté de Médecine, 06107 Nice Cédex 2, France
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Peraldi P, Vandenbussche E, Augereau B. [Bad clinical results of cemented caps with metal-backed acetabular components. 124 cases with 21 months follow-up]. Rev Chir Orthop Reparatrice Appar Mot 1998; 83:561-5. [PMID: 9587621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF THE STUDY The authors reviewed with short term follow-up 124 total hip arthroplasties using a cemented metal-backed acetabular component. The purpose of the study was to evaluate clinical and radiological results because of early periacetabular radiolucent lines reported by Ritter. MATERIAL AND METHODS Surgical procedures were performed in 1988 and 1989 with Saint-Antoine prosthesis (PSA) including cemented titanium metal-backed socket. Functional results were appreciated with Postel-Merle d'Aubigne's score. Radiological results were appreciated using De Lee and Charnley's criterias for radiolucent lines and Yoder's criterias for socket's migrations. We studied correlation between radiolucent line and age, weight, hip disease, associated bone graft, socket size and technical errors. RESULTS With short term follow-up (21 months), we found 60.4 per cent hips with a maximal PMA score (18) with an average score of 17.5 per cent. We observed 26.4 per cent of complete periacetabular radiolucent lines with 3 sockets loosening with migration. No significant correlation were found between radiolucent lines and age, weight, hip disease, associated bone graft, socket size, and technical errors. DISCUSSION This periacetabular radiolucent line rate was comparable to the results of the series using such a cemented metal-backed socket. This rate was clearly higher than the results of others series using cemented polyethylene sockets. These bad results were not correlated to those of finite elements analysis. We think that this is due to metal-backed socket excessive rigidity. CONCLUSION Because of this high periacetabular radiolucent line rate, despite of finite elements analysis results, we no more use cemented metal-backed acetabular socket since 1991.
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Affiliation(s)
- P Peraldi
- Service de Chirurgie Orthopédique, Hôpital Rothschild, Paris
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Peraldi P, Spiegelman B. TNF-alpha and insulin resistance: summary and future prospects. Mol Cell Biochem 1998; 182:169-75. [PMID: 9609126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
While the causes of obesity remain elusive, the relationship between obesity and insulin resistance is a well-established fact [1]. Insulin resistance is defined as a smaller than normal response to a certain dose of insulin, and contributes to several pathological problems of obese patients such as hyperlipidemia, arteriosclerosis and hypertension. Several pieces of evidence indicate that the cytokine tumor necrosis factor a (TNF-alpha) is an important player in the state of insulin resistance observed during obesity. In this review we will try to summarize what is known about the function of TNF-alpha in insulin resistance during obesity and how TNF-alpha interferes with insulin signaling.
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Affiliation(s)
- P Peraldi
- Dana Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
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Vandenbussche E, Peraldi P, Massin P, Augereau B, Lavaste F. [Acetabulum deformations after implantation of a cemented cup with or without metal-back component. An in vitro comparative study of monopodal load]. Rev Chir Orthop Reparatrice Appar Mot 1998; 83:409-15. [PMID: 9452792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF THE STUDY The purpose of this study was to find a biomechanical explanation for a clinical failure of metal backed acetabular components. Periacetabular deformations were measured on fresh cadaver bones equipped with strain-gauge rosettes. MATERIAL AND METHODS Two skeletons, including pelvic bone, the two last lumbar vertebrae, and both femurs were maintained in unipodal equilibrium using metallic cables for muscle simulation. Loads were applied up to 700 N the approximating average body weight. A comparative study of periacetabular deformations was performed: right sides of each pelvic bone were implanted with conventional cemented implants, and left sides with metal backed cemented implants of same diameter and size. RESULTS Significant differences were noted: whereas no modification was brought by implantation of conventional cemented sockets, periacetabular deformations were reduced and smoothed after implantation of cemented metal backed implants. Such results are in agreement with recently published data obtained, using the finite element analysis method. DISCUSSION A study of pelvic ring and acetabular walls displacement was performed, but the authors couldn't find any clinical relevance to this biomechanical study.
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Affiliation(s)
- E Vandenbussche
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Rothschild, Paris
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Affiliation(s)
- P Peraldi
- Boston Dana Farber Cancer Institute, Harvard Medical School, Massachusetts 02115, USA
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Abstract
TNF-alpha has been shown to be an important mediator of insulin resistance linked to obesity. This cytokine induces insulin resistance, at least in part, through inhibition of the tyrosine kinase activity of the insulin receptor. Recently, a new class of compounds, the antidiabetic thiazolidinediones (TZDs), has been shown to improve insulin resistance in obesity and non-insulin-dependent diabetes mellitus in both rodents and man. Here we show that TZDs have powerful effects on the ability of TNF-alpha to alter the most proximal steps of insulin signaling, including tyrosine phosphorylation of the insulin receptor and its major substrate, IRS-1, and activation of PI3-kinase. Troglitazone or pioglitazone essentially eliminate the reduction in tyrosine phosphorylation of IR and IRS-1 caused by TNF-alpha in fat cells, even at relatively high doses (25 ng/ml). That this effect of TZDs operates through activation of the nuclear receptor PPARgamma/ RXR complex is shown by the fact that similar effects are observed with other PPARgamma/RXR ligands such as 15 deoxy Delta12,14PGJ2 and LG268. The TZDs do not inhibit all TNF-alpha signaling in that the transcription factor NF-kB is still induced well. These data indicate that TZDs can specifically block certain actions of TNF-alpha related to insulin resistance, suggesting that this block may contribute to their antidiabetic actions.
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Affiliation(s)
- P Peraldi
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Peraldi P, Spiegelman BM. [TNF-alpha: molecular tie between obesity and insulin resistance]. Journ Annu Diabetol Hotel Dieu 1997:149-59. [PMID: 9296970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- P Peraldi
- Dana Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
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Calleja V, Ruiz Enríquez P, Filloux C, Peraldi P, Baron V, Van Obberghen E. The effect of cyclic adenosine monophosphate on the mitogen-activated protein kinase pathway depends on both the cell type and the type of tyrosine kinase-receptor. Endocrinology 1997; 138:1111-20. [PMID: 9048617 DOI: 10.1210/endo.138.3.5027] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The mitogen-activated protein kinase (MAP kinase) is a key participant in growth factor-stimulated intracellular events such as proliferation and differentiation. We and others have previously described a cross-talk between the MAP kinase pathway and the cAMP pathway. Indeed, in several cell lines and, in particular in fibroblasts, an increase in the level of cAMP produced an inhibition of MAP kinase together with decreased cell proliferation. In contrast, in PC12 cells, cAMP induced an increase in the NGF-induced activation of MAP kinase concomitantly with augmented NGF-induced differentiation. Therefore, it has been proposed that the cellular context is important for the nature of the cAMP effects on growth factor-stimulated MAP kinase activity. Here we show that the type of tyrosine kinase receptor stimulated also participates in the nature of the cAMP effect. Thus, in NIH3T3 fibroblasts expressing NGF receptors (NIH3T3/trk cells) we found that cAMP potentiates NGF-stimulated ERK1 and MEK1 activities, whereas in NIH3T3 fibroblasts expressing insulin receptors (NIH3T3/IR cells) we saw no effect of cAMP on the activation of insulin-stimulated ERK1 and MEK1. In PC12 cells and in Rat1 fibroblasts expressing insulin receptors (PC12/IR and Rat1/IR cells) we observed, respectively, a potentiation and an inhibition of insulin-stimulated ERK1 activity. In addition, cAMP does not seem to modify the basal nor growth factor-stimulated She or IRS-1 tyrosine phosphorylation in the different cell lines studied. Finally, we observed that cAMP inhibited serum- and insulin-induced, but not NGF-induced, cell proliferation in NIH3T3 cells. However, cAMP potentiated insulin-stimulated cell differentiation in PC12/IR cells. These results led us to conclude that the cAMP effect on cell proliferation in NIH3T3 fibroblasts and PC12/IR cells appears to be correlated, in part, with the effect of cAMP on the MAP kinase pathway, but by itself this pathway cannot fully account for these observations.
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Affiliation(s)
- V Calleja
- INSERM U145, Faculté de Médecine, Nice, France
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Peraldi P, Hotamisligil GS, Buurman WA, White MF, Spiegelman BM. Tumor necrosis factor (TNF)-alpha inhibits insulin signaling through stimulation of the p55 TNF receptor and activation of sphingomyelinase. J Biol Chem 1996; 271:13018-22. [PMID: 8662983 DOI: 10.1074/jbc.271.22.13018] [Citation(s) in RCA: 328] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Tumor necrosis factor (TNF)-alpha plays a central role in the state of insulin resistance associated with obesity. It has previously been shown that one important mechanism by which TNF-alpha interferes with insulin signaling is through the serine phosphorylation of insulin receptor substrate-1 (IRS-1), which can then function as an inhibitor of the tyrosine kinase activity of the insulin receptor (IR). However, the receptors and the signaling pathway used by TNF-alpha that mediate the inhibition of IR activity are unknown. We show here that human TNF-alpha, which binds only to the murine p55 TNF receptor (TNFR), is as effective at inhibiting insulin-dependent tyrosine phosphorylation of IR and IRS-1 in adipocytes and myeloid 32D cells as murine TNF-alpha, which binds to both p55 TNFR and p75 TNFR. Likewise, antibodies that are specific agonists for p55 TNFR or p75 TNFR demonstrate that stimulation of p55 TNFR is sufficient to inhibit insulin signaling, though a small effect can also be seen with antibodies to p75 TNFR. Exogenous sphingomyelinase and ceramides, known to be formed by activation of p55 TNFR, inhibit IR and IRS-1 tyrosine phosphorylation and convert IRS-1 into an inhibitor of IR tyrosine kinase in vitro. Myeloid 32D cells expressing IR and IRS-1 are sensitive to this inhibition, but cells expressing IR and IRS-2 are resistant, pointing to an important difference in the biological function between IRS-1 and IRS-2. These data strongly suggest that TNF-alpha inhibits insulin signaling via stimulation of p55 TNFR and sphingomyelinase activity, which results in the production of an inhibitory form of IRS-1.
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Affiliation(s)
- P Peraldi
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Hotamisligil GS, Peraldi P, Budavari A, Ellis R, White MF, Spiegelman BM. IRS-1-mediated inhibition of insulin receptor tyrosine kinase activity in TNF-alpha- and obesity-induced insulin resistance. Science 1996; 271:665-8. [PMID: 8571133 DOI: 10.1126/science.271.5249.665] [Citation(s) in RCA: 1789] [Impact Index Per Article: 63.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is an important mediator of insulin resistance in obesity and diabetes through its ability to decrease the tyrosine kinase activity of the insulin receptor (IR). Treatment of cultured murine adipocytes with TNF-alpha was shown to induce serine phosphorylation of insulin receptor substrate 1 (IRS-1) and convert IRS-1 into an inhibitor of the IR tyrosine kinase activity in vitro. Myeloid 32D cells, which lack endogenous IRS-1, were resistant to TNF-alpha-mediated inhibition of IR signaling, whereas transfected 32D cells that express IRS-1 were very sensitive to this effect of TNF-alpha. An inhibitory form of IRS-1 was observed in muscle and fat tissues from obese rats. These results indicate that TNF-alpha induces insulin resistance through an unexpected action of IRS-1 to attenuate insulin receptor signaling.
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Affiliation(s)
- G S Hotamisligil
- Department of Cellular and Molecular Biology, Dana-Farber Cancer Institute, Boston, MA, USA
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Mondoloni P, Vandenbussche E, Peraldi P, Augereau B. [Instability of the elbow after supracondylar humeral non-union in cubitus varus rotation. Apropos of 2 cases observed in adults]. Rev Chir Orthop Reparatrice Appar Mot 1996; 82:757-61. [PMID: 9097863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The authors describe 2 originals cases with a painful snap or "recurrent" elbow instability in adults after displaced supracondylar fractures in childhood, with a malunion in varus and internal rotation. Varus and internal rotation of the distal humeral epiphysis were responsible for instability because of elbow kinematic modification. Extra-articular osteotomy fixed with a plate allowed pain relief, stability, and range of motion improvement.
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Affiliation(s)
- P Mondoloni
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Rothschild, Paris
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Vandenbussche E, Peraldi P, Naouri JF, Rougereau G, Augereau B. [Four part valgus impacted fractures of the upper extremity of humerus: ilium graft reconstruction. Apropos of 8 cases]. Rev Chir Orthop Reparatrice Appar Mot 1996; 82:658-62. [PMID: 9091985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE OF THE STUDY We present the results of an original technique for reconstruction of valgus-impacted humeral head using autologous iliac bone. MATERIAL AND METHODS Between 1992 and 1993, 8 patients (average age 66 years, range 43 to 79 years) with four-part valgus impacted proximal humeral fractures were operated with the aim of preserving the humeral head. All fractures were treated with open reduction and were stabilized only with autologous bone. This procedure provided fixation without osteosynthesis. Using a deltopectoral approach the impacted segment of the humeral head was raised, the void was filled with autologous three-cortical iliac bone graft, and the tuberosities were relocated with the goal of anatomic reconstruction. The assessment included clinical examination including Constant's score, radiographic examination and MRI examination. Only one patient was not available for the review at follow-up evaluation (minimum 12 months, average 16 months). RESULTS According to Constant's criteria, two results were excellent, two very good, one good, one fair and one patient were considered failure. Average Constant's score was 62; average score in comparison with the healthy side was 76 per cent. Radiographic findings showed in all cases healing and incorporation of the graft. MRI results showed only one asymptomatic partial avascular necrosis (14 per cent). DISCUSSION This specific type of displaced four-part fracture of the proximal humerus which consists of valgus impaction of the head fragment without lateral displacement has a rate of avascular necrosis lower than that of other displaced four-part fractures. Blood supply of the articular segment is maintained via the periosteum extending to the medial part of the anatomic humeral neck. These data authorized the authors to propose a new conservative treatment for four-part valgus impacted proximal humeral fractures.
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Affiliation(s)
- E Vandenbussche
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Rothschild, Paris
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Peraldi P, Frödin M, Barnier JV, Calleja V, Scimeca JC, Filloux C, Calothy G, Van Obberghen E. Regulation of the MAP kinase cascade in PC12 cells: B-Raf activates MEK-1 (MAP kinase or ERK kinase) and is inhibited by cAMP. FEBS Lett 1995; 357:290-6. [PMID: 7835430 DOI: 10.1016/0014-5793(94)01376-c] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In PC12 cells, cAMP stimulates the MAP kinase pathway by an unknown mechanism. Firstly, we examined the role of calcium ion mobilization and of protein kinase C in cAMP-stimulated MAP kinase activation. We show that cAMP stimulates p44mapk independently of these events. Secondly, we studied the role of B-Raf in this process. We observed that NGF, PMA and cAMP induce the phosphorylation of B-Raf as well as an upward shift in its electrophoretic mobility. We show that B-Raf is activated following NGF and PMA treatment of PC12 cells, and that it can phosphorylate and activate MEK-1. However, cAMP inhibits B-Raf autokinase activity as well as its ability to phosphorylate and activate MEK-1. This inhibition is likely to be due to a direct effect since we found that PKA phosphorylates B-Raf in vitro. Further, we show that B-Raf binds to p21ras, but more important, this binding to p21ras is virtually abolished with B-Raf from PC12 cells treated with CPT-cAMP. Hence, these data indicate that the PKA-mediated phosphorylation of B-Raf hampers its interaction with p21ras, which is responsible for the PKA-mediated decrease in B-Raf activity. Finally, our work suggests that in PC12 cells, cAMP stimulates MAP kinase through the activation of an unidentified MEK kinase and/or the inhibition of a MEK phosphatase.
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Affiliation(s)
- P Peraldi
- INSERM U 145, Faculté de Médecine, Nice, France
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Peraldi P, Zhao Z, Filloux C, Fischer EH, Van Obberghen E. Protein-tyrosine-phosphatase 2C is phosphorylated and inhibited by 44-kDa mitogen-activated protein kinase. Proc Natl Acad Sci U S A 1994; 91:5002-6. [PMID: 8197172 PMCID: PMC43918 DOI: 10.1073/pnas.91.11.5002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Protein-tyrosine-phosphatase 2C (PTP2C, also named SHPTP2, SHPTP3, or PTP1D) is a cytosolic enzyme with two Src homology 2 domains. We have investigated its regulation by phosphorylation in PC12 rat pheochromocytoma cells. In untreated cells, PTP2C was phosphorylated predominantly on serine residues. A 5-min treatment with epidermal growth factor (EGF) induced an increase in phosphorylation on threonine and, to a lesser degree, on serine. After 45 min of exposure to EGF, PTP2C phosphorylation returned to basal levels. Using an in vitro kinase assay, we found that the 44-kDa mitogen-activated protein kinase, p44mapk, phosphorylated PTP2C on serine and threonine residues. This phosphorylation resulted in a pronounced inhibition of PTP2C enzyme activity measured with phosphorylated EGF receptors as substrate. Moreover, in intact PC12 cells, PTP2C was also inhibited following a short EGF treatment, but its activity returned to normal when the exposure to EGF was maintained for 45 min. The profile of this response to EGF can be inversely correlated to that of the stimulatory action of EGF on p44mapk. These data suggest that the EGF-induced regulation of PTP2C activity is mediated by p44mapk. These findings provide evidence for an additional role of the mitogen-activated protein kinase cascade--namely, the regulation of a PTP.
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Affiliation(s)
- P Peraldi
- Institut National de la Santé et de la Recherche Médicale Unité 145, Faculté de Médecine, Nice, France
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Frödin M, Peraldi P, Van Obberghen E. Cyclic AMP activates the mitogen-activated protein kinase cascade in PC12 cells. J Biol Chem 1994; 269:6207-14. [PMID: 7907091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Mitogen-activated protein (MAP) kinases are activated in response to a large variety of extracellular signals, including growth factors, hormones, and neurotransmitters, which activate distinct intracellular signaling pathways. Their activation by the cAMP-dependent pathway, however, has not been reported. In rat pheochromocytoma PC12 cells, we demonstrate here a stimulation of the MAP kinase isozyme extracellular signal-regulated kinase 1 (ERK1) following elevation of intracellular cAMP after exposure of the cells to isobutylmethylxanthine, cholera toxin, forskolin, or cAMP-analogues. cAMP acted synergistically with phorbol ester, an activator of protein kinase C, in the stimulation of ERK1. In accordance with this observation, the peptide neurotransmitter pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), which stimulates cAMP production as well as phosphatidylinositol breakdown in PC12 cells, was an efficient activator of ERK1. In combination with various growth factors, cAMP acted in a more than additive manner on ERK1 activity. Elevation of intracellular cAMP increased in vivo 32P-labeling of ERK1, suggesting that cAMP stimulated ERK1 by activating MAP kinase kinase, an immediate upstream activator of ERK1 in the MAP kinase cascade. Supporting this view, forskolin and a cAMP analogue were found to increase the activity of MAP kinase kinase in PC12 cells, alone as well as in combination with phorbol ester. PACAP38 also stimulated in vivo 32P-labeling of ERK1 and MAP kinase kinase activity. Finally, cAMP or PACAP38 increased by 3-fold nerve growth factor-stimulated neurite formation in PC12 cells, which may be correlated with the potentiating effect of these agents on nerve growth factor-stimulated ERK1 activity.
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Affiliation(s)
- M Frödin
- Institut National de la Santé et de la Recherche Médicale U 145, Faculté de Médecine, Nice, France
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Peraldi P, Van Obberghen E. Insulin and tumor-promoting agent regulate an inhibitor of the 44-kDa mitogen-activated protein kinase/extracellular signal-regulated protein kinase 1 in fibroblasts. Eur J Biochem 1993; 218:815-21. [PMID: 8281932 DOI: 10.1111/j.1432-1033.1993.tb18436.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have examined the negative regulation of the 44-kDa mitogen-activated protein kinase (MAP kinase), also known as extracellular signal-regulated protein kinase 1 (ERK1), in NIH3T3 cells transfected with an expression plasmid encoding the human insulin receptor (NHIR cells). In these cells ERK1 activation is induced by two distinct stimuli, insulin and tumor-promoting agent (TPA). While insulin was found to be more potent than TPA for ERK1 activation, both stimuli produced the same transient activation pattern with a rapid peak (reached within 5 min) followed by a fast decrease within 20 min. By performing reconstitution experiments with immunoprecipitated ERK1 and lysates from NHIR cells, we showed that extracts from untreated cells exhibit an ERK1 inhibitory activity. Interestingly, this inhibitor was found to be regulated by insulin and TPA with a profile that is the mirror image of ERK1 activity. This repressing activity was sensitive to tyrosine phosphatase inhibitors, such as sodium orthovanadate and zinc acetate, but it was not affected by serine/threonine phosphatase inhibitors, such as sodium fluoride and okadaic acid. Moreover, it was possible to observe in extracts of NHIR cells an activity dephosphorylating ERK1. The time course of this phosphatase activity was comparable to that of the ERK1 inhibition, suggesting that the repressing activity could reflect a dephosphorylating action. Interestingly, phosphatase 2A treatment of extracts from 5-min TPA-treated cells (where the ERK1 inhibitor was weak) was able to induce an increase in the ERK1 repressing activity. This suggests that serine/threonine dephosphorylation of ERK1 inhibitor leads to an increase in its activity. In summary, we have shown that NHIR cells contain a regulatable ERK1 inhibitor, which is likely to be due to tyrosine phosphatase(s). We would like to suggest that such activities are key components in the fine-tuning of the MAP kinase cascade.
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Affiliation(s)
- P Peraldi
- INSERM U 145, Faculté de Médecine, Nice, France
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Peraldi P, Scimeca JC, Filloux C, Van Obberghen E. Regulation of extracellular signal-regulated protein kinase-1 (ERK-1; pp44/mitogen-activated protein kinase) by epidermal growth factor and nerve growth factor in PC12 cells: implication of ERK1 inhibitory activities. Endocrinology 1993; 132:2578-85. [PMID: 8389283 DOI: 10.1210/endo.132.6.8389283] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In PC12 cells, extracellular signal-regulated kinase-1 (ERK1 or pp44/mitogen-activated protein kinase) is stimulated in response to epidermal growth factor (EGF) and nerve growth factor (NGF). This stimulation is rapid and short-lived after EGF activation. In contrast, NGF promotes a swift, but persistent, ERK1 stimulation. We took advantage of this difference in activation pattern to study the negative regulation of ERK1. Using antibodies to the C-terminus of ERK1, we performed in vitro reconstitution experiments with immunoprecipitated ERK1 from stimulated cells and extracts from PC12 cells incubated with EGF or NGF for various periods of times. Using this approach, we showed that extracts from unstimulated cells reduce ERK1 activity. Upon exposure of cells to NGF or EGF, we found that the inhibitory activity had a pattern opposite that of ERK1 phosphorylation and activity. Indeed, the highest ERK1 activation was associated with the lowest ERK1-repressing activity and vice versa. This ERK1 inhibitory activity was found to be sensitive mainly to sodium orthovanadate and to a lesser extent to zinc acetate. Interestingly, okadaic acid decreased ERK1-repressing activity from unstimulated cells when tested with ERK1 from 5-min NGF-treated cells, but not with ERK1 from 5-min EGF-treated cells. Hence, ERK1 appears to be regulated differently after stimulation of cells with EGF compared to NGF. We show that cell extracts promote ERK1 dephosphorylation. Indeed, we were able to detect a phosphatase activity toward in vivo phosphorylated ERK1 that was regulated differently after NGF and EGF treatments of the cells, and that has a profile of regulation similar to that of the ERK1 inhibitory activity. This regulatable phosphatase activity was also observed using in vitro phosphorylated ERK1. Taken together, our data provide evidence that ERK1 is negatively controlled by a phosphatase(s) that can undergo differential modulation depending on the stimuli used.
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Affiliation(s)
- P Peraldi
- INSERM U 145, Faculté de Médecine, Nice, France
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Nguyen TT, Scimeca JC, Filloux C, Peraldi P, Carpentier JL, Van Obberghen E. Co-regulation of the mitogen-activated protein kinase, extracellular signal-regulated kinase 1, and the 90-kDa ribosomal S6 kinase in PC12 cells. Distinct effects of the neurotrophic factor, nerve growth factor, and the mitogenic factor, epidermal growth factor. J Biol Chem 1993; 268:9803-10. [PMID: 8387505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We recently characterized the association of the 44-kDa mitogen-activated protein kinase, also known as extracellular-regulated kinase 1 (ERK1), with the 90-kDa ribosomal S6 kinase (pp90rsk), one of its putative substrates in intact PC12 cells. Using antibodies to ERK1 that precipitate a functional ERK1.pp90rsk phosphoprotein complex, we demonstrate here the regulation of both kinases by various stimuli. In mouse fibroblasts expressing human insulin receptors, insulin and vanadate swiftly stimulated ERK1 activity within 5 min. While the hormonal effect was short-lived, vanadate led to a first peak followed by a progressively increasing second phase. In PC12 cells, epidermal growth factor, which is a growth promoting factor, provokes a rapid but evanescent activation of ERK1. In contrast, nerve growth factor (NGF), which acts as a neuronal differentiation factor for PC12 cells, induced a swift monophasic response followed by a sustained second phase. This strikingly different pattern of ERK1 stimulation by NGF and epidermal growth factor was associated to a contrasting effect on ERK1 cellular translocation. Thus, NGF induced a nuclear translocation of ERK1, while epidermal growth factor was without noticeable effect on ERK1 localization. In both cell systems all effectors tested stimulated ERK1 phosphorylation on both threonine and tyrosine residues in an 1:1 ratio. During ERK1 inactivation, phosphothreonine and phosphotyrosine were dephosphorylated in a similar fashion. Concurrent with ERK1 activation was the de novo appearance of phosphothreonine and an increase in phosphoserine on pp90rsk. The pp90rsk phosphothreonine content paralleled the ERK1 activity more closely than the phosphoserine level. These results provide compelling evidence that in fibroblasts and PC12 cells ERK1 plays a direct role in the phosphorylation of pp90rsk and that pp90rsk represents a physiologically relevant substrate of extracellular-regulated kinases. Finally, we would like to suggest that the differentiating action of NGF in PC12 cells might be due, at least in part, to the conjunction of its sustained and robust stimulation of ERK1 and pp90rsk, and of its induction of ERK1 nuclear translocation.
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Affiliation(s)
- T T Nguyen
- Institut National de la Santé et de la Recherche Médicale U145, Faculté de Médecine, Nice, France
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Nguyen T, Scimeca J, Filloux C, Peraldi P, Carpentier J, Van Obberghen E. Co-regulation of the mitogen-activated protein kinase, extracellular signal-regulated kinase 1, and the 90-kDa ribosomal S6 kinase in PC12 cells. Distinct effects of the neurotrophic factor, nerve growth factor, and the mitogenic factor, epidermal growth factor. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)98418-8] [Citation(s) in RCA: 160] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Abstract
Membrane-associated tyrosine phosphatase activities were studied in two distinct states of insulin resistance: diabetes and pregnancy. Using a novel immunoenzymatic assay with intact insulin-like growth factor-I (IGF-I) and insulin receptors as substrates, we show that phosphotyrosine-protein phosphatases (PTP-ases) from normal rat tissues induce a decrease in tyrosine phosphorylation of both receptors. Membrane fractions from kidney, brain, and liver contain the highest PTP-ase activity toward the insulin receptor. After 20-day streptozotocin-induced diabetes, PTP-ase activities are increased by 70% in the placenta, reduced by 40-50% in liver and skeletal muscle, and remained unchanged in the nonclassical insulin target tissues, kidney and brain. In general, the dephosphorylation of IGF-I receptor follows a pattern similar to that of insulin receptor except in red skeletal muscle in which it is not modified. Pregnancy also induces alterations of liver PTP-ases similar to those elicited by diabetes with a 50% reduction of insulin and IGF-I receptor dephosphorylation. This effect of pregnancy is further potentiated by diabetes. The alterations in the activity of hepatic PTP-ases from diabetic and pregnant rats are associated with a decreased autophosphorylation of the insulin receptor, suggesting that the diminution of phosphatase activity might be associated to the state of receptor phosphorylation and activation. Our data demonstrate that alterations of PTP-ases in insulin target tissues are found in two insulin-resistant states, one characterized by hyperinsulinemia, pregnancy and one by insulinopenia, streptozotocin-diabetes. These observations suggest a possible relationship between the defective activity of receptor tyrosine kinases and membrane-associated phosphatases from insulin responsive tissues.
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Peraldi P, Hauguel-de Mouzon S, Alengrin F, Van Obberghen E. Dephosphorylation of human insulin-like growth factor I (IGF-I) receptors by membrane-associated tyrosine phosphatases. Biochem J 1992; 285 ( Pt 1):71-8. [PMID: 1322128 PMCID: PMC1132746 DOI: 10.1042/bj2850071] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The insulin-like growth factor-I (IGF-I) receptor exhibits structural and functional similarities to the insulin receptor. Although the regulation of the insulin-receptor tyrosine kinase has been extensively investigated, the mechanisms involved in phosphorylation/dephosphorylation of the IGF-I receptor have received only little attention. To obtain a better understanding of the mode of IGF-I action, we have investigated the effects of protein phosphotyrosine phosphatases (PTPases) on the phosphorylation status of the IGF-I receptor. The dephosphorylation of the human IGF-I receptor by membrane-associated tyrosine phosphatases was studied by an immuno-enzymic assay based on the recognition of phosphotyrosine residues by anti-phosphotyrosine antibodies. Using intact IGF-I receptors as substrates, we show that they could be completely dephosphorylated by different cellular PTPases. Three pieces of evidence indicate that receptor dephosphorylation takes place on phosphotyrosine, i.e. the inhibition profile of phosphatase activity by zinc and vanadate, its absolute requirement for thiol compounds and the diminution of [32P]phosphotyrosine labelling of the beta subunit assessed by SDS/PAGE and phosphoamino acid analysis. Tyrosine kinase activity and autophosphorylation of the IGF-I receptor were decreased in a dose-dependent manner by PTPases, indicating that partial dephosphorylation of the receptor was associated with a decrease in its intrinsic activity. The sensitivity of the activated human IGF-I receptor to dephosphorylation on tyrosine leads to the speculation that IGF-I receptor activity might be regulated by mechanisms such as those described for the insulin receptor. Further investigation of the pathways of IGF-I receptor dephosphorylation will contribute to define the role(s) of PTPases in the overall mechanism of IGF-I signalling.
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Affiliation(s)
- P Peraldi
- INSERM U 145, Faculté de Médecine, Nice, France
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Bonnaud G, Gest J, Peraldi P, Rose Y. [Bronchial hypotonia and hypovascularization in unilateral pulmonary transparency]. J Fr Med Chir Thorac 1967; 21:45-52. [PMID: 5593865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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