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Semantic Signature: Comparative Interpretation of Gene Expression on a Semantic Space. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:5174503. [PMID: 27242916 PMCID: PMC4868886 DOI: 10.1155/2016/5174503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/23/2016] [Indexed: 11/17/2022]
Abstract
Background. Interpretation of microarray data remains challenging because biological meaning should be extracted from enormous numeric matrices and be presented explicitly. Moreover, huge public repositories of microarray dataset are ready to be exploited for comparative analysis. This study aimed to provide a platform where essential implication of a microarray experiment could be visually expressed and various microarray datasets could be intuitively compared. Results. On the semantic space, gene sets from Molecular Signature Database (MSigDB) were plotted as landmarks and their relative distances were calculated by Lin's semantic similarity measure. By formal concept analysis, a microarray dataset was transformed into a concept lattice with gene clusters as objects and Gene Ontology terms as attributes. Concepts of a lattice were located on the semantic space reflecting semantic distance from landmarks and edges between concepts were drawn; consequently, a specific geographic pattern could be observed from a microarray dataset. We termed a distinctive geography shared by microarray datasets of the same category as “semantic signature.” Conclusions. “Semantic space,” a map of biological entities, could serve as a universal platform for comparative microarray analysis. When microarray data were displayed on the semantic space as concept lattices, “semantic signature,” characteristic geography for a microarray experiment, could be discovered.
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Philippou A, Barton ER. Optimizing IGF-I for skeletal muscle therapeutics. Growth Horm IGF Res 2014; 24:157-163. [PMID: 25002025 PMCID: PMC4665094 DOI: 10.1016/j.ghir.2014.06.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/09/2014] [Indexed: 12/13/2022]
Abstract
It is virtually undisputed that IGF-I promotes cell growth and survival. However, the presence of several IGF-I isoforms, vast numbers of intracellular signaling components, and multiple receptors results in a complex and highly regulated system by which IGF-I actions are mediated. IGF-I has long been recognized as one of the critical factors for coordinating muscle growth, enhancing muscle repair, and increasing muscle mass and strength. How to optimize this panoply of pathways to drive anabolic processes in muscle as opposed to aberrant growth in other tissues is an area that deserves focus. This review will address how advances in the bioavailability, potency, and tissue response of IGF-I can provide new potential directions for skeletal muscle therapeutics.
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Affiliation(s)
- Anastassios Philippou
- Department of Physiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Elisabeth R Barton
- Department of Anatomy and Cell Biology, School of Dental Medicine, and Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, PA, USA.
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Nagel SA, Keuper M, Zagotta I, Enlund E, Ruperez AI, Debatin KM, Wabitsch M, Fischer-Posovszky P. Up-regulation of Bcl-2 during adipogenesis mediates apoptosis resistance in human adipocytes. Mol Cell Endocrinol 2014; 382:368-376. [PMID: 24397922 DOI: 10.1016/j.mce.2013.10.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/16/2013] [Accepted: 10/21/2013] [Indexed: 01/05/2023]
Abstract
Targeting apoptotic pathways in adipocytes has been suggested as a pharmacological approach to treat obesity. However, adipocyte apoptosis was identified as a cause for macrophage infiltration into adipose tissue. Previous studies suggest that mature adipocytes are less sensitive to apoptotic stimuli as compared to preadipocytes. Here, we aimed to identify proteins mediating apoptosis resistance in adipocytes. Our data revealed that the anti-apoptotic protein Bcl-2 (B-cell lymphoma 2) is up-regulated during adipogenic differentiation. Bcl-2 overexpression in preadipocytes lowers their apoptosis sensitivity to the level of mature adipocytes. Vice versa Bcl-2 knockdown in adipocytes sensitizes these cells to CD95-induced apoptosis. Taken together, our findings suggest a shift in the balance of pro-apoptotic and anti-apoptotic molecules during adipogenesis resulting in a higher apoptosis resistance. This study sheds new light on the apoptotic process in human fat cells and may constitute a new possible target for the specific regulation of adipose tissue mass.
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Affiliation(s)
- Stella A Nagel
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Michaela Keuper
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Ivana Zagotta
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Eveliina Enlund
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Azahara Iris Ruperez
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Klaus-Michael Debatin
- Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Martin Wabitsch
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany.
| | - Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany.
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Ito M, Nagasawa M, Omae N, Tsunoda M, Ishiyama J, Ide T, Akasaka Y, Murakami K. A novel JNK2/SREBP-1c pathway involved in insulin-induced fatty acid synthesis in human adipocytes. J Lipid Res 2013; 54:1531-1540. [PMID: 23515281 DOI: 10.1194/jlr.m031591] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Insulin plays important roles in apoptosis and lipid droplet (LD) formation, and it is one of the determinants involved in increasing fat mass. However, the mechanisms underlying insulin-induced enlargement of fat mass remain unclear. Our previous study suggested that insulin-induced increases in LDs are related to c-Jun N-terminal kinase (JNK)2-mediated upregulation of cell death-inducing DNA fragmentation factor-α-like effector (CIDE)C in human adipocytes. However, other genes involved in insulin/JNK2-induced LD formation are unknown. Here, we explored insulin/JNK2-regulated genes to clarify the mechanism of enlargement of LDs. Microarray analysis revealed that an insulin/JNK2 pathway mostly regulates expression of genes involved in lipid metabolism, including sterol regulatory element binding protein (SREBP)-1, a key transcription factor of lipogenesis. The JNK inhibitor SP600125 blocked insulin-induced upregulation of SREBP-1c expression. Small interfering RNA-mediated depletion of JNK2 suppressed insulin-induced nuclear accumulation of the active form of SREBP-1 protein and upregulation of SREBP-1c. Furthermore, depletion of JNK2 attenuated insulin-induced upregulation of SREBP-1c target lipogenic enzymes, leading to reduced de novo fatty acid synthesis. In addition, JNK2 coimmunoprecipitated with SREBP-1, reinforcing the correlation between JNK2 and SREBP-1. These results suggest that SREBP-1c is a novel insulin/JNK2-regulated gene and that the JNK2/SREBP-1c pathway mediates insulin-induced fatty acid synthesis, which may lead to enlargement of LDs in human adipocytes.
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Affiliation(s)
- Minoru Ito
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
| | - Michiaki Nagasawa
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan.
| | - Naoki Omae
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
| | - Masaki Tsunoda
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
| | - Junichi Ishiyama
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
| | - Tomohiro Ide
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
| | - Yunike Akasaka
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
| | - Koji Murakami
- Discovery Research Laboratories, Kyorin Pharmaceutical Company Limited, Tochigi 329-0114, Japan
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Affiliation(s)
- Jeff Holly
- Academic Units of Surgery and Child Health, University of Bristol, Bristol, United Kingdom
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Ito M, Nagasawa M, Omae N, Ide T, Akasaka Y, Murakami K. Differential regulation of CIDEA and CIDEC expression by insulin via Akt1/2- and JNK2-dependent pathways in human adipocytes. J Lipid Res 2011; 52:1450-60. [PMID: 21636835 DOI: 10.1194/jlr.m012427] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Both insulin and the cell death-inducing DNA fragmentation factor-α-like effector (CIDE) family play important roles in apoptosis and lipid droplet formation. Previously, we reported that CIDEA and CIDEC are differentially regulated by insulin and contribute separately to insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. However, the upstream signals of CIDE proteins remain unclear. Here, we investigated the signaling molecules involved in insulin regulation of CIDEA and CIDEC expression. The phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and PI-103 blocked both insulin-induced downregulation of CIDEA and upregulation of CIDEC. The Akt inhibitor API-2 and the c-Jun N-terminal kinase (JNK) inhibitor SP600125 selectively inhibited insulin regulation of CIDEA and CIDEC expression, respectively, whereas the MAPK/ERK kinase inhibitor U0126 and the p38 inhibitor SB203580 did not. Small interfering RNA-mediated depletion of Akt1/2 prevented insulin-induced downregulation of CIDEA and inhibition of apoptosis. Depletion of JNK2, but not JNK1, inhibited insulin-induced upregulation of CIDEC and lipid droplet enlargement. Furthermore, insulin increased both Akt and JNK phosphorylation, which was abrogated by the PI3K inhibitors. These results suggest that insulin regulates CIDEA and CIDEC expression via PI3K, and it regulates expression of each protein via Akt1/2- and JNK2-dependent pathways, respectively, in human adipocytes.
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Affiliation(s)
- Minoru Ito
- Discovery Research Laboratories, Kyorin Pharmaceutical Co. Ltd., Tochigi 329-0114, Japan
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Rosenow A, Arrey TN, Bouwman FG, Noben JP, Wabitsch M, Mariman EC, Karas M, Renes J. Identification of Novel Human Adipocyte Secreted Proteins by Using SGBS Cells. J Proteome Res 2010; 9:5389-401. [DOI: 10.1021/pr100621g] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Anja Rosenow
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Tabiwang N. Arrey
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Freek G. Bouwman
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Jean-Paul Noben
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Martin Wabitsch
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Edwin C.M. Mariman
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Michael Karas
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
| | - Johan Renes
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University, Maastricht, The Netherlands, Cluster of Excellence “Macromolecular Complexes”, Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt am Main, Germany, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, and Department of Pediatrics, University of Ulm, Ulm, Germany
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8
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Ito M, Nagasawa M, Hara T, Ide T, Murakami K. Differential roles of CIDEA and CIDEC in insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. J Lipid Res 2010; 51:1676-84. [PMID: 20154362 DOI: 10.1194/jlr.m002147] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Both insulin and the cell death-inducing DNA fragmentation factor-alpha-like effector (CIDE) family play important roles in apoptosis and lipid droplet formation. However, regulation of the CIDE family by insulin and the contribution of the CIDE family to insulin actions remain unclear. Here, we investigated whether insulin regulates expression of the CIDE family and which subtypes contribute to insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. Insulin decreased CIDEA and increased CIDEC but not CIDEB mRNA expression. Starvation-induced apoptosis in adipocytes was significantly inhibited when insulin decreased the CIDEA mRNA level. Small interfering RNA-mediated depletion of CIDEA inhibited starvation-induced apoptosis similarly to insulin and restored insulin deprivation-reduced adipocyte number, whereas CIDEC depletion did not. Lipid droplet size of adipocytes was increased when insulin increased the CIDEC mRNA level. In contrast, insulin-induced enlargement of lipid droplets was markedly abrogated by depletion of CIDEC but not CIDEA. Furthermore, depletion of CIDEC, but not CIDEA, significantly increased glycerol release from adipocytes. These results suggest that CIDEA and CIDEC are novel genes regulated by insulin in human adipocytes and may play key roles in the effects of insulin, such as anti-apoptosis and lipid droplet formation.
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Affiliation(s)
- Minoru Ito
- Discovery Research Laboratories, Kyorin Pharmaceutical Co. Ltd., 2399-1, Nogi, Nogi-machi, Shimotsuga-gun, Tochigi 329-0114, Japan
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9
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Julien DC, Richardson CC, Beaux MF, McIlroy DN, Hill RA. In vitro proliferating cell models to study cytotoxicity of silica nanowires. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2010; 6:84-92. [DOI: 10.1016/j.nano.2009.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 02/12/2009] [Accepted: 03/30/2009] [Indexed: 12/29/2022]
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Grant AC, Ortiz-Colòn G, Doumit ME, Buskirk DD. Optimization of in vitro conditions for bovine subcutaneous and intramuscular preadipocyte differentiation. J Anim Sci 2007; 86:73-82. [PMID: 17911240 DOI: 10.2527/jas.2007-0379] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The objective of these experiments was to develop an in vitro cell culture system for differentiation of bovine preadipocytes, which will permit examination of differences in differentiation between intramuscular (i.m.) and subcutaneous (s.c.) bovine preadipocytes. Stromal-vascular cells from bovine i.m. and s.c. adipose depots were isolated and cultured. Clonally derived s.c. preadipocytes were used to determine the ability of insulin, bovine serum lipids, octanoate, acetic acid, dexamethasone (DEX), and troglitazone (TRO) to elicit differentiation of these cells when added to serum-free medium. Addition of 10 and 20 microL/mL of a commercially available serum lipids supplement to low-glucose Dulbecco's modified Eagle's medium containing 280 nM insulin increased glycerol-3-phosphate dehydrogenase (GPDH) activity (P < 0.01). Inclusion of 1.25 to 10 microM TRO to medium containing 280 nM insulin and 20 microL/ mL serum lipids supplement also increased GPDH activity (P < 0.001) compared with 0 microM TRO. The combination of 280 nM insulin, 1 mM octanoate, and 10 mM acetic acid, with 48 h exposure to 0.25 microM DEX caused morphological differentiation in a small number of cells but did not stimulate GPDH activity (P = 0.99). When used together, 280 nM insulin, 20 microL/mL of serum lipids supplement, 40 microM TRO, and 0.25 microM DEX stimulated differentiation compared with the aforementioned treatment (P < 0.001). Omission of TRO or insulin from this medium reduced GPDH activity by 68% (P < 0.001), whereas removal of DEX tended to reduce GPDH activity (P = 0.06). Preadipocytes from s.c. (n = 3) and i.m. (n = 2) adipose tissues of 3 steers were used to determine the effects of TRO on differentiation using the established conditions. Forty to sixty microM TRO enhanced differentiation compared with 0 microM TRO (P < 0.02) in both depots. No depot differences in response to TRO were detected (P = 0.32). These data demonstrate that bovine preadipocytes are capable of differentiation in response to combinations of insulin, serum lipids, DEX, and TRO. Although TRO enhanced differentiation of bovine preadipocytes, no differential effects of TRO on the differentiation of s.c. and i.m. cells were detected.
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Affiliation(s)
- A C Grant
- Departments of Animal Science, Michigan State University, East Lansing 48824-1225, USA
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Kurmasheva RT, Houghton PJ. IGF-I mediated survival pathways in normal and malignant cells. Biochim Biophys Acta Rev Cancer 2006; 1766:1-22. [PMID: 16844299 DOI: 10.1016/j.bbcan.2006.05.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 05/23/2006] [Accepted: 05/25/2006] [Indexed: 02/07/2023]
Abstract
The type-I and -II insulin-like growth factors (IGF-I, II) are now established as survival- or proliferation-factors in many in vitro systems. Of note IGFs provide trophic support for multiple cell types or organ cultures explanted from various species, and delay the onset of programmed cell death (apoptosis) through the mitochondrial (intrinsic pathway) or by antagonizing activation of cytotoxic cytokine signaling (extrinsic pathway). In some instances, IGFs protect against other forms of death such as necrosis or autophagy. The effect of IGFs on cell survival appears to be context specific, being determined both by the cell origin (tissue specific) and the cellular stress that induces loss of cellular viability. In many human cancers, there is a strong association with dysregulated IGF signaling, and this association has been extensively reviewed recently. IGF-regulation is also disrupted in childhood cancers as a consequence of chromosomal translocations. IGFs are implicated also in acute renal failure, traumatic injury to brain tissue, and cardiac disease. This article focuses on the role of IGFs and their cellular signaling pathways that provide survival signals in stressed cells.
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Affiliation(s)
- Raushan T Kurmasheva
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105-2794, USA
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Kokai LE, Rubin JP, Marra KG. The potential of adipose-derived adult stem cells as a source of neuronal progenitor cells. Plast Reconstr Surg 2006; 116:1453-60. [PMID: 16217495 DOI: 10.1097/01.prs.0000182570.62814.e3] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Adipose-derived adult stem cells are a population of mesenchymal stem cells extracted from discarded adipose tissue. Many have reported the differentiation of adipose-derived stem cells into chondrocytes, myocytes, osteoblasts, and, most recently, neural progenitor cells. This article covers the current state of the potential of the differentiation of adipose-derived stem cells into neuronal cells and an overview of their potential as adult stem therapies for neurological disorders. It has been reported that adipose-derived stem cells are capable of undergoing neuronal differentiation using protocols similar to that of Woodbury et al., which reported the differentiation of bone marrow stromal cells specifically into neurons. However, the transdifferentiation of bone marrow stromal cells into neuronal cells has recently fallen under intense criticism, which will likely place the plasticity of adipose-derived stem cells under scrutiny as well. To date, no group has produced evidence that adipose-derived stem cells are capable of differentiating to mature, functional neuronal cells in vitro. However, recent in vivo studies with adipose-derived stem cells are promising.
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Affiliation(s)
- Lauren E Kokai
- Division of Plastic and Reconstructive Surgery, Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
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Fischer-Posovszky P, Tornqvist H, Debatin KM, Wabitsch M. Inhibition of death-receptor mediated apoptosis in human adipocytes by the insulin-like growth factor I (IGF-I)/IGF-I receptor autocrine circuit. Endocrinology 2004; 145:1849-59. [PMID: 14691011 DOI: 10.1210/en.2003-0985] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Adipose tissue mass is reflected by the volume and the number of adipocytes and is subject to homeostatic regulation involving cell death mechanisms. In this study we have investigated the mechanisms of apoptosis in human preadipocytes and adipocytes that may play a role in the regulation of adipose tissue mass. We found that death receptors (CD95, TNF-related apoptosis-inducing ligand receptors 1 and 2, and TNF receptor 1) are expressed in human fat cells and that apoptosis can be induced by specific ligands. Sensitivity to apoptosis could be stimulated by an inhibitor of biosynthesis. In addition, inhibition of auto-/paracrine action of IGF-I dramatically sensitizes human adipocytes for death ligand-induced apoptosis. Phosphoinositide 3-kinase and, to a weaker extent, p38 MAPK are involved in IGF-I-mediated survival. IGF-I protects human fat cells from apoptosis by maintaining the expression of antiapoptotic proteins, Bcl-x(L) and Fas-associated death domain-like IL-1-converting enzyme inhibitory protein. In conclusion, we identified mechanisms of apoptosis induction in human fat cells. We furthermore demonstrate that human fat cells protect themselves from apoptosis by IGF-I in an auto-/paracrine manner.
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Mulligan C, Rochford J, Denyer G, Stephens R, Yeo G, Freeman T, Siddle K, O'Rahilly S. Microarray analysis of insulin and insulin-like growth factor-1 (IGF-1) receptor signaling reveals the selective up-regulation of the mitogen heparin-binding EGF-like growth factor by IGF-1. J Biol Chem 2002; 277:42480-7. [PMID: 12213819 DOI: 10.1074/jbc.m206206200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin and insulin-like growth factor-1 (IGF-1) act through highly homologous receptors that engage similar intracellular signaling pathways, yet these hormones serve largely distinct physiological roles in the control of metabolism and growth, respectively. In an attempt to uncover the molecular mechanisms underlying their divergent functions, we compared insulin receptor (IR) and IGF-1 receptor (IGF-1R) regulation of gene expression by microarray analysis, using 3T3-L1 cells expressing either TrkC/IR or TrkC/IGF-1R chimeric receptors to ensure the highly selective activation of each receptor tyrosine kinase. Following stimulation of the chimeric receptors for 4 h, we detected 11 genes to be differentially regulated, of which 10 were up-regulated to a greater extent by the IGF-1R. These included genes involved in adhesion, transcription, transport, and proliferation. The expression of mRNA encoding heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent mitogen, was markedly increased by IGF-1R but not IR activation. This effect was dependent on MAPK, but not phosphatidylinositol 3-kinase, and did not require an autocrine loop through the epidermal growth factor receptor. HB-EGF mitogenic activity was detectable in the medium of 3T3-L1 preadipocytes expressing activated IGF-1R but not IR, indicating that the transcriptional response is accompanied by a parallel increase in mature HB-EGF protein. The differential abilities of the IR and IGF-1R tyrosine kinases to stimulate the synthesis and release of a growth factor may provide, at least in part, an explanation for the greater role of the IGF-1R in the control of cellular proliferation.
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Affiliation(s)
- Claire Mulligan
- University of Cambridge, Department of Clinical Biochemistry, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QR, United Kingdom
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Gilmore AP, Valentijn AJ, Wang P, Ranger AM, Bundred N, O'Hare MJ, Wakeling A, Korsmeyer SJ, Streuli CH. Activation of BAD by therapeutic inhibition of epidermal growth factor receptor and transactivation by insulin-like growth factor receptor. J Biol Chem 2002; 277:27643-50. [PMID: 12011069 DOI: 10.1074/jbc.m108863200] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Novel cancer chemotherapeutics are required to induce apoptosis by activating pro-apoptotic proteins. Both epidermal growth factor (EGF) and insulin-like growth factor (IGF) provide potent survival stimuli in many epithelia, and activation of their receptors is commonly observed in solid human tumors. Here we demonstrate that blockade of the EGF receptor by a new drug in phase III clinical trails for cancer, ZD1839, potently induces apoptosis in mammary epithelial cell lines and primary cultures, as well as in a primary pleural effusion from a breast cancer patient. We identified the mechanism of apoptosis induction by ZD1839. We showed that it prevents cell survival by activating the pro-apoptotic protein BAD. Moreover, we demonstrate that IGF transactivates the EGF receptor and that ZD1839 blocks IGF-mediated phosphorylation of MAPK and BAD. Many cancer therapies kill tumor cells by inducing apoptosis as a consequence of targeting DNA; however, the threshold at which apoptosis can be triggered through DNA damage is often different from that in normal cells. Our results indicate that by targeting a growth factor-mediated survival signaling pathway, BAD phosphorylation can be manipulated therapeutically to induce apoptosis.
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Affiliation(s)
- Andrew P Gilmore
- School of Biological Sciences, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.
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16
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Buckley DA, Cheng A, Kiely PA, Tremblay ML, O'Connor R. Regulation of insulin-like growth factor type I (IGF-I) receptor kinase activity by protein tyrosine phosphatase 1B (PTP-1B) and enhanced IGF-I-mediated suppression of apoptosis and motility in PTP-1B-deficient fibroblasts. Mol Cell Biol 2002; 22:1998-2010. [PMID: 11884589 PMCID: PMC133665 DOI: 10.1128/mcb.22.7.1998-2010.2002] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The insulin-like growth factor type I (IGF-I) receptor (IGF-IR), activated by its ligands IGF-I and IGF-II, can initiate several signal transduction pathways that mediate suppression of apoptosis, proliferation, differentiation, and transformation. Here we investigated the regulation of IGF-IR activation and function by protein tyrosine phosphatase 1B (PTP-1B). Coexpression of PTP-1B with a beta-chain construct of the IGF-IR (betaWT) inhibited IGF-IR kinase activity in fission yeast Schizosaccharomyces pombe, in COS cells, and in IGF-IR-deficient fibroblasts. In both spontaneously immortalized and simian virus 40 T antigen-transformed embryonic fibroblast cell lines derived from PTP-1B knockout mice, IGF-I induced higher levels of IGF-IR autophosphorylation and kinase activity than were induced in PTP-1B-expressing control cells. PTP-1B-deficient cells exhibited enhanced IGF-I-mediated protection from apoptosis in response to serum withdrawal or etoposide killing, as well as enhanced plating efficiency and IGF-I-mediated motility. Reexpression of PTP-1B in spontaneously immortalized fibroblasts resulted in decreased IGF-IR and AKT activation, as well as decreased protection from apoptosis and decreased motility. These findings demonstrate that PTP-1B can regulate IGF-IR kinase activity and function and that loss of PTP-1B can enhance IGF-I-mediated cell survival, growth, and motility in transformed cells.
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Affiliation(s)
- Deirdre A Buckley
- Cell Biology Laboratory, Department of Biochemistry and Bioscience Research Institute, National University of Ireland, Cork, Ireland
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Reusch JEB, Klemm DJ. Inhibition of cAMP-response element-binding protein activity decreases protein kinase B/Akt expression in 3T3-L1 adipocytes and induces apoptosis. J Biol Chem 2002; 277:1426-32. [PMID: 11694510 DOI: 10.1074/jbc.m107923200] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
White adipose tissue mass is governed by competing processes that control lipid synthesis and storage, the development of new adipocytes, and their survival. We have shown that the transcription factor cAMP-response element-binding protein (CREB) participates in adipogenesis, with constitutively active forms of CREB inducing adipocyte differentiation and dominant negative forms of CREB blocking this process. In other cell types, CREB and related factors have been shown to play important roles in survival and apoptosis. Here we demonstrate that reduction of CREB activity by ectopic expression of the dominant negative CREB, KCREB, induces apoptosis of mature 3T3-L1 adipocytes in culture. Death by apoptosis was confirmed by increased nuclear condensation, changes in membrane morphology, and increased DNA fragmentation. Gene microarray analysis indicated that KCREB expression increased expression of several pro-apoptotic genes like Interleukin Converting Enzyme and decreased the expression of the anti-apoptotic signaling molecule, Akt/protein kinase B. Finally, introduction of constitutively active CREB, CREB-DIEDML, blocked death of mature adipocytes treated with TNF-alpha. The data indicate that CREB plays a central role in adipocyte survival, perhaps by regulating the expression of certain pro- and anti-apoptotic genes. These results not only extend the role of CREB in adipocyte biology but also highlight the general developmental and survival role of this factor in numerous cell and tissue types.
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Affiliation(s)
- Jane E B Reusch
- Endocrinology and Pulmonary and Critical Sections, and Research Service, Veterans Affairs Medical Center, Denver, Colorado 80220, USA
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Qian H, Hausman DB, Compton MM, Martin RJ, Della-Fera MA, Hartzell DL, Baile CA. TNFalpha induces and insulin inhibits caspase 3-dependent adipocyte apoptosis. Biochem Biophys Res Commun 2001; 284:1176-83. [PMID: 11414707 DOI: 10.1006/bbrc.2001.5100] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regulation of fat cell number by apoptosis is proposed to be part of a normal physiological cycle in adipose growth and development. To investigate this process, cultured rat adipocytes were treated with various concentrations of tumor necrosis factor alpha (TNFalpha) and/or insulin to determine the roles of these factors in adipocyte apoptosis. The cells were analyzed by flow cytometry using a TUNEL assay. TNFalpha increased adipocyte apoptosis in a dose-dependent fashion. TNFalpha-mediated apoptosis was detectable within 6 h of treatment and continued to increase with time. Decreasing media insulin concentration from 8.5 to 0.85 nM resulted in increased adipocyte apoptosis, whereas high doses of insulin protected adipocytes from TNFalpha-induced apoptosis. TNFalpha-activated apoptosis was accompanied by an increase in caspase 3 activity and could be inhibited by a caspase 3-specific inhibitor. These data suggest that adipose tissue cell number is regulated, in part, by an apoptotic signaling pathway that involves TNFalpha, insulin, and caspase 3.
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Affiliation(s)
- H Qian
- Department of Foods and Nutrition, University of Georgia, Athens, Georgia 30602, USA
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