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Masliukov PM. Changes of Signaling Pathways in Hypothalamic Neurons with Aging. Curr Issues Mol Biol 2023; 45:8289-8308. [PMID: 37886966 PMCID: PMC10605528 DOI: 10.3390/cimb45100523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/01/2023] [Accepted: 10/10/2023] [Indexed: 10/28/2023] Open
Abstract
The hypothalamus is an important regulator of autonomic and endocrine functions also involved in aging regulation. The aging process in the hypothalamus is accompanied by disturbed intracellular signaling including insulin/insulin-like growth factor-1 (IGF-1)/growth hormone (GH), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (AKT)/the mammalian target of rapamycin (mTOR), mitogen activated protein kinase (MAPK), janus kinase (JAK)/signal transducer and activator of transcription (STAT), AMP-activated protein kinase (AMPK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB), and nitric oxide (NO). In the current review, I have summarized the current understanding of the changes in the above-mentioned pathways in aging with a focus on hypothalamic alterations.
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Affiliation(s)
- Petr M Masliukov
- Department Normal Physiology, Yaroslavl State Medical University, ul. Revoliucionnaya 5, 150000 Yaroslavl, Russia
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2
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Rapraeger AC. Syndecans and Their Synstatins: Targeting an Organizer of Receptor Tyrosine Kinase Signaling at the Cell-Matrix Interface. Front Oncol 2021; 11:775349. [PMID: 34778093 PMCID: PMC8578902 DOI: 10.3389/fonc.2021.775349] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 09/27/2021] [Indexed: 01/11/2023] Open
Abstract
Receptor tyrosine kinases (RTKs) and integrin matrix receptors have well-established roles in tumor cell proliferation, invasion and survival, often functioning in a coordinated fashion at sites of cell-matrix adhesion. Central to this coordination are syndecans, another class of matrix receptor, that organize RTKs and integrins into functional units, relying on docking motifs in the syndecan extracellular domains to capture and localize RTKs (e.g., EGFR, IGF-1R, VEGFR2, HER2) and integrins (e.g., αvβ3, αvβ5, α4β1, α3β1, α6β4) to sites of adhesion. Peptide mimetics of the docking motifs in the syndecans, called “synstatins”, prevent assembly of these receptor complexes, block their signaling activities and are highly effective against tumor cell invasion and survival and angiogenesis. This review describes our current understanding of these four syndecan-coupled mechanisms and their inhibitory synstatins (SSTNIGF1R, SSTNVEGFR2, SSTNVLA-4, SSTNEGFR and SSTNHER2).
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Affiliation(s)
- Alan C Rapraeger
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
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Liu Q, Zhai L, Han M, Shi D, Sun Z, Peng S, Wang M, Zhang C, Gao J, Yan W, Jiang Q, Chen D, Xu Q, Tan M, Sun Y. SHP2 inhibition attenuates osteoarthritis by maintaining homeostasis of cartilage metabolism via the DOK1/UPP1/uridine cascade. Arthritis Rheumatol 2021; 74:462-474. [PMID: 34569725 DOI: 10.1002/art.41988] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 09/10/2021] [Accepted: 09/23/2021] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Protein tyrosine kinases (PTKs) regulate osteoarthritis (OA) progression by activating a series of signal transduction pathways. However, the roles of protein tyrosine phosphatases (PTPs) in OA remain obscure. METHODS The expression of 107 PTP genes in human OA cartilage was analyzed based on a single-cell sequencing dataset. The enzyme activity of the PTP SHP2 was detected in primary chondrocytes after interleukin (IL)-1β treatment and in human OA cartilage. Destabilized medial meniscus (DMM) model and IL-1β-stimulated primary mouse chondrocytes were treated with an SHP2 inhibitor and celecoxib (a clinical drug for the treatment of OA). The function of SHP2 in OA pathogenesis was further verified in Aggrecan-CreERT ; SHP2 flox/flox mice. The downstream protein expression profile and dephosphorylated substrate of SHP2 were examined by tandem mass tag (TMT) labeling-based global proteomic and stable isotope labeling using amino acids in cell culture (SILAC)-labeled tyrosine phosphoproteomic analysis, respectively. RESULTS SHP2 enzyme activity significantly increased in human OA samples with serious articular cartilage injury and in IL-1β-stimulated chondrocytes. Pharmacological inhibition or genetic deletion of SHP2 ameliorated OA progression. SHP2 inhibitors dramatically reduced the expression of cartilage degradation-related genes and simultaneously promoted the expression of cartilage synthesis-related genes. Mechanistically, SHP2 inhibition suppressed the dephosphorylation of DOK1 and subsequently reduced the expression of uridine phosphorylase 1 and increased uridine level, thereby contributing to the homeostasis of cartilage metabolism. CONCLUSIONS SHP2 is a novel accelerator of the imbalance in the cartilage homeostasis. Specific inhibition of SHP2 may ameliorate OA by maintaining the anabolic and catabolic balance.
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Affiliation(s)
- Qianqian Liu
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China
| | - Linhui Zhai
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Mingrui Han
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China
| | - Dongquan Shi
- Department of Sports Medicine and Adult Reconstructive Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, 210008, Jiangsu, China
| | - Ziying Sun
- Department of Sports Medicine and Adult Reconstructive Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, 210008, Jiangsu, China
| | - Shuang Peng
- Institute of Pharmacology, University of Bern, Bern, Switzerland
| | - Meijing Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China
| | - Chenyang Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China
| | - Jian Gao
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China
| | - Wenjin Yan
- Department of Sports Medicine and Adult Reconstructive Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, 210008, Jiangsu, China
| | - Qing Jiang
- Department of Sports Medicine and Adult Reconstructive Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, 210008, Jiangsu, China
| | - Dijun Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China
| | - Qiang Xu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Minjia Tan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Yang Sun
- State Key Laboratory of Pharmaceutical Biotechnology, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Life Sciences, Nanjing University, 163 Xianlin Avenue, 210023, Jiangsu, China.,Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
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Hirst NL, Nebel JC, Lawton SP, Walker AJ. Deep phosphoproteome analysis of Schistosoma mansoni leads development of a kinomic array that highlights sex-biased differences in adult worm protein phosphorylation. PLoS Negl Trop Dis 2020; 14:e0008115. [PMID: 32203512 PMCID: PMC7089424 DOI: 10.1371/journal.pntd.0008115] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 02/05/2020] [Indexed: 12/16/2022] Open
Abstract
Although helminth parasites cause enormous suffering worldwide we know little of how protein phosphorylation, one of the most important post-translational modifications used for molecular signalling, regulates their homeostasis and function. This is particularly the case for schistosomes. Herein, we report a deep phosphoproteome exploration of adult Schistosoma mansoni, providing one of the richest phosphoprotein resources for any parasite so far, and employ the data to build the first parasite-specific kinomic array. Complementary phosphopeptide enrichment strategies were used to detect 15,844 unique phosphopeptides mapping to 3,176 proteins. The phosphoproteins were predicted to be involved in a wide range of biological processes and phosphoprotein interactome analysis revealed 55 highly interconnected clusters including those enriched with ribosome, proteasome, phagosome, spliceosome, glycolysis, and signalling proteins. 93 distinct phosphorylation motifs were identified, with 67 providing a ‘footprint’ of protein kinase activity; CaMKII, PKA and CK1/2 were highly represented supporting their central importance to schistosome function. Within the kinome, 808 phosphorylation sites were matched to 136 protein kinases, and 68 sites within 37 activation loops were discovered. Analysis of putative protein kinase-phosphoprotein interactions revealed canonical networks but also novel interactions between signalling partners. Kinomic array analysis of male and female adult worm extracts revealed high phosphorylation of transformation:transcription domain associated protein by both sexes, and CDK and AMPK peptides by females. Moreover, eight peptides including protein phosphatase 2C gamma, Akt, Rho2 GTPase, SmTK4, and the insulin receptor were more highly phosphorylated by female extracts, highlighting their possible importance to female worm function. We envision that these findings, tools and methodology will help drive new research into the functional biology of schistosomes and other helminth parasites, and support efforts to develop new therapeutics for their control. Schistosomes are formidable parasites that cause the debilitating and life-threatening disease human schistosomiasis. We need to better understand the cellular biology of these parasites to develop novel strategies for their control. Within cells, a process called protein phosphorylation controls many aspects of molecular communication or ‘signalling’ and is central to cellular function and homeostasis. Here, using complementary strategies, we have performed the first in-depth characterisation and functional annotation of protein phosphorylation events in schistosomes, providing one of the richest phosphoprotein resources for any parasite to date. Using this knowledge, we have developed a novel tool to simultaneously evaluate signalling processes in these worms and highlight sex-biased differences in adult worm protein phosphorylation. Several proteins were found to be more greatly phosphorylated by female worm extracts, suggesting their possible importance to female worm function. This work will help drive new research into the fundamental biology of schistosomes, as well as related parasites, and will support efforts to develop new drug or vaccine-based therapeutics for their control.
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Affiliation(s)
- Natasha L. Hirst
- School of Life Sciences Pharmacy and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, United Kingdom
| | - Jean-Christophe Nebel
- School of Computer Science and Mathematics, Kingston University, Penrhyn Road, Kingston upon Thames, United Kingdom
| | - Scott P. Lawton
- School of Life Sciences Pharmacy and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, United Kingdom
| | - Anthony J. Walker
- School of Life Sciences Pharmacy and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, United Kingdom
- * E-mail:
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Abstract
Insulin-like growth factors (IGFs) bind specifically to the IGF1 receptor on the cell surface of targeted tissues. Ligand binding to the α subunit of the receptor leads to a conformational change in the β subunit, resulting in the activation of receptor tyrosine kinase activity. Activated receptor phosphorylates several substrates, including insulin receptor substrates (IRSs) and Src homology collagen (SHC). Phosphotyrosine residues in these substrates are recognized by certain Src homology 2 (SH2) domain-containing signaling molecules. These include, for example, an 85 kDa regulatory subunit (p85) of phosphatidylinositol 3-kinase (PI 3-kinase), growth factor receptor-bound 2 (GRB2) and SH2-containing protein tyrosine phosphatase 2 (SHP2/Syp). These bindings lead to the activation of downstream signaling pathways, PI 3-kinase pathway and Ras-mitogen-activated protein kinase (MAP kinase) pathway. Activation of these signaling pathways is known to be required for the induction of various bioactivities of IGFs, including cell proliferation, cell differentiation and cell survival. In this review, the well-established IGF1 receptor signaling pathways required for the induction of various bioactivities of IGFs are introduced. In addition, we will discuss how IGF signals are modulated by the other extracellular stimuli or by themselves based on our studies.
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Affiliation(s)
- Fumihiko Hakuno
- Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Shin-Ichiro Takahashi
- Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
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Maile LA, Busby WH, Xi G, Gollahan KP, Flowers W, Gafbacik N, Gafbacik S, Stewart K, Merricks EP, Nichols TC, Bellinger DA, Clemmons DR. An anti-αVβ3 antibody inhibits coronary artery atherosclerosis in diabetic pigs. Atherosclerosis 2017; 258:40-50. [PMID: 28189040 DOI: 10.1016/j.atherosclerosis.2017.01.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 01/19/2017] [Accepted: 01/25/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND AIMS Diabetes is a major risk factor for the development of atherosclerosis. Hyperglycemia stimulates vascular smooth muscle cells (VSMC) to secrete ligands that bind to the αVβ3 integrin, a receptor that regulates VSMC proliferation and migration. This study determined whether an antibody that had previously been shown to block αVβ3 activation and to inhibit VSMC proliferation and migration in vitro, inhibited the development of atherosclerosis in diabetic pigs. METHODS Twenty diabetic pigs were maintained on a high fat diet for 22 weeks. Ten received injections of anti-β3 F(ab)2 and ten received control F(ab)2 for 18 weeks. RESULTS The active antibody group showed reduction of atherosclerosis of 91 ± 9% in the left main, 71 ± 11%, in left anterior descending, 80 ± 10.2% in circumflex, and 76 ± 25% in right coronary artery, (p < 0.01 compared to lesions areas from corresponding control treated arteries). There were significant reductions in both cell number and extracellular matrix. Histologic analysis showed neointimal hyperplasia with macrophage infiltration, calcifications and cholesterol clefts. Antibody treatment significantly reduced number of macrophages contained within lesions, suggesting that this change contributed to the decrease in lesion cellularity. Analysis of the biochemical changes within the femoral arteries that received the active antibody showed a 46 ± 12% (p < 0.05) reduction in the tyrosine phosphorylation of the β3 subunit of αVβ3 and a 40 ± 14% (p < 0.05) reduction in MAP kinase activation. CONCLUSIONS Blocking ligand binding to the αVβ3 integrin inhibits its activation and attenuates increased VSMC proliferation that is induced by chronic hyperglycemia. These changes result in significant decreases in atherosclerotic lesion size in the coronary arteries. The results suggest that this approach may have efficacy in treating the proliferative phase of atherosclerosis in patients with diabetes.
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Affiliation(s)
- L A Maile
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - W H Busby
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - G Xi
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - K P Gollahan
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - W Flowers
- Department of Animal Science, NC State University, Raleigh, NC, USA
| | - N Gafbacik
- Department of Animal Science, NC State University, Raleigh, NC, USA
| | - S Gafbacik
- Department of Animal Science, NC State University, Raleigh, NC, USA
| | - K Stewart
- Department of Animal Science, NC State University, Raleigh, NC, USA
| | - E P Merricks
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - T C Nichols
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - D A Bellinger
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA
| | - D R Clemmons
- Department of Medicine, UNC School of Medicine, Chapel Hill, NC, USA.
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Subcellular compartmentalization of docking protein-1 contributes to progression in colorectal cancer. EBioMedicine 2016; 8:159-172. [PMID: 27428427 PMCID: PMC4919572 DOI: 10.1016/j.ebiom.2016.05.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 04/19/2016] [Accepted: 05/04/2016] [Indexed: 12/20/2022] Open
Abstract
Full-length (FL) docking protein-1 (DOK1) is an adapter protein which inhibits growth factor and immune response pathways in normal tissues, but is frequently lost in human cancers. Small DOK1 variants remain in cells of solid tumors and leukemias, albeit, their functions are elusive. To assess the so far unknown role of DOK1 in colorectal cancer (CRC), we generated DOK1 mutants which mimic the domain structure and subcellular distribution of DOK1 protein variants in leukemia patients. We found that cytoplasmic DOK1 activated peroxisome-proliferator-activated-receptor-gamma (PPARγ) resulting in inhibition of the c-FOS promoter and cell proliferation, whereas nuclear DOK1 was inactive. PPARγ-agonist increased expression of endogenous DOK1 and interaction with PPARγ. Forward translation of this cell-based signaling model predicted compartmentalization of DOK1 in patients. In a large series of CRC patients, loss of DOK1 protein was associated with poor prognosis at early tumor stages (*p = 0.001; n = 1492). In tumors with cytoplasmic expression of DOK1, survival was improved, whereas nuclear localization of DOK1 correlated with poor outcome, indicating that compartmentalization of DOK1 is critical for CRC progression. Thus, DOK1 was identified as a prognostic factor for non-metastatic CRC, and, via its drugability by PPARγ-agonist, may constitute a potential target for future cancer treatments. Forward translation of a cell-based signaling model predicted clinical relevance for DOK1 in colorectal cancer (CRC). DOK1 is an independent prognostic factor in CRC patients, and its loss associated with poor survival. Cancer cell growth inhibition by DOK1 was increased (“drugable”) by PPARγ-agonist. Poor survival due to failure to respond to clinical therapies prevents effective treatment of cancer. Thus, there is a high medical need for novel drug targets and biomarkers. DOK1 blocks pro-cancer signaling in the healthy body, but is often lost in tumors. We show that colorectal cancer patients who are positive for DOK1 have a better survival outcome than patients who are negative. Anti-diabetic drugs up-regulated DOK1 and promoted its protective actions against tumor cells. Our study therefore suggests DOK1 as a marker for good prognosis and as a potential drug target for therapy of colorectal cancer.
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Abstract
Leptin is an adipose-derived cytokine that has an important role in bodyweight homeostasis and energy balance. There are a number of studies which have suggested that leptin and its receptors dysregulation play a critical role in the development of malignancies including hematological malignancies, mainly via activation of the JAK/STAT pathway which regulates downstream signaling pathways such as PI3K/AKT signaling and ERK1/2. In this review, current understandings of leptin/leptin receptors mediated pathogenesis in various lymphoid malignancies are described. Blocking of the leptin receptor might be a unique therapeutic approach for many hematological malignancies.
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Affiliation(s)
- Shahab Uddin
- a Translational Research Institute, Academic Health System, Hamad Medical Corporation , Doha , Qatar
| | - Ramzi M Mohammad
- a Translational Research Institute, Academic Health System, Hamad Medical Corporation , Doha , Qatar
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Maile LA, Busby WH, Gollahon KA, Flowers W, Garbacik N, Garbacik S, Stewart K, Nichols T, Bellinger D, Patel A, Dunbar P, Medlin M, Clemmons D. Blocking ligand occupancy of the αVβ3 integrin inhibits the development of nephropathy in diabetic pigs. Endocrinology 2014; 155:4665-75. [PMID: 25171599 PMCID: PMC4239428 DOI: 10.1210/en.2014-1318] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hyperglycemia stimulates secretion of αVβ3 ligands from vascular cells, including endothelial cells, resulting in activation of the αVβ3 integrin. This study determined whether blocking ligand occupancy of αVβ3 would inhibit the development of diabetic nephropathy. Ten diabetic pigs received an F(ab)2 fragment of an antibody directed against the extracellular domain of the β3-subunit, and 10 received a control IgG F(ab)2 for 18 weeks. Nondiabetic pigs excreted 115 ± 50 μg of protein/mg creatinine compared with control F(ab)2-treated diabetic animals (218 ± 57 μg/mg), whereas diabetic animals treated with the anti-β3 F(ab)2 excreted 119 ± 55 μg/mg (P < .05). Mesangial volume/glomerular volume increased to 21 ± 2.4% in control-treated diabetic animals compared with 14 ± 2.8% (P < .01) in animals treated with active antibody. Diabetic animals treated with control F(ab)2 had significantly less glomerular podocin staining compared with nondiabetic animals, and this decrease was attenuated by treatment with anti-β3 F(ab)2. Glomerular basement membrane thickness was increased in the control, F(ab)2-treated diabetic animals (212 ± 14 nm) compared with nondiabetic animals (170 ± 8.8 nm), but it was unchanged (159.9 ± 16.4 nm) in animals receiving anti-β3 F(ab)2. Podocyte foot process width was greater in control, F(ab)2-treated, animals (502 ± 34 nm) compared with animals treated with the anti-β3 F(ab)2 (357 ± 47 nm, P < .05). Renal β3 tyrosine phosphorylation decreased from 13 934 ± 6437 to 6730 ± 1524 (P < .01) scanning units in the anti-β3-treated group. We conclude that administration of an antibody that inhibits activation of the β3-subunit of αVβ3 that is induced by hyperglycemia attenuates proteinuria and early histologic changes of diabetic nephropathy, suggesting that it may have utility in preventing the progression of this disease complication.
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Affiliation(s)
- Laura A Maile
- Department of Medicine (L.A.M., W.H.B., K.A.G., T.N., D.B., A.P., P.D., M.M., D.C.), University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599; and Department of Animal Science (W.F., N.G., S.G., K.S.), North Carolina State University, Raleigh, North Carolina 27695
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Barrett A, Evans IM, Frolov A, Britton G, Pellet-Many C, Yamaji M, Mehta V, Bandopadhyay R, Li N, Brandner S, Zachary IC, Frankel P. A crucial role for DOK1 in PDGF-BB-stimulated glioma cell invasion through p130Cas and Rap1 signalling. J Cell Sci 2014; 127:2647-58. [PMID: 24762811 DOI: 10.1242/jcs.135988] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
DOK1 regulates platelet-derived growth factor (PDGF)-BB-stimulated glioma cell motility. Mechanisms regulating tumour cell motility are essential for invasion and metastasis. We report here that PDGF-BB-mediated glioma cell invasion and migration are dependent on the adaptor protein downstream of kinase 1 (DOK1). DOK1 is expressed in several glioma cell lines and in tumour biopsies from high-grade gliomas. DOK1 becomes tyrosine phosphorylated upon PDGF-BB stimulation of human glioma cells. Knockdown of DOK1 or expression of a DOK1 mutant (DOK1FF) containing Phe in place of Tyr at residues 362 and 398, resulted in inhibition of both the PDGF-BB-induced tyrosine phosphorylation of p130Cas (also known as BCAR1) and the activation of Rap1. DOK1 colocalises with tyrosine phosphorylated p130Cas at the cell membrane of PDGF-BB-treated cells. Expression of a non-tyrosine-phosphorylatable substrate domain mutant of p130Cas (p130Cas15F) inhibited PDGF-BB-mediated Rap1 activation. Knockdown of DOK1 and Rap1 inhibited PDGF-BB-induced chemotactic cell migration, and knockdown of DOK1 and Rap1 and expression of DOK1FF inhibited PDGF-mediated three-dimensional (3D) spheroid invasion. These data show a crucial role for DOK1 in the regulation of PDGF-BB-mediated tumour cell motility through a p130Cas-Rap1 signalling pathway. [Corrected]
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Affiliation(s)
- Angela Barrett
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Ian M Evans
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Antonina Frolov
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Gary Britton
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Caroline Pellet-Many
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Maiko Yamaji
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Vedanta Mehta
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | | | - Ningning Li
- Division of Neuropathology and Department of Neurodegenerative Disease, Institute of NeurologyUniversity College LondonLondon WC1E 6JJUK
| | - Sebastian Brandner
- Division of Neuropathology and Department of Neurodegenerative Disease, Institute of NeurologyUniversity College LondonLondon WC1E 6JJUK
| | - Ian C Zachary
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
| | - Paul Frankel
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, Rayne Building, University College London, London WC1E 6JJ, UK
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Skov V, Cangemi C, Gram J, Christensen MM, Grodum E, Sørensen D, Argraves WS, Henriksen JE, Rasmussen LM. Metformin, but not rosiglitazone, attenuates the increasing plasma levels of a new cardiovascular marker, fibulin-1, in patients with type 2 diabetes. Diabetes Care 2014; 37:760-6. [PMID: 24135389 DOI: 10.2337/dc13-1022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The extracellular matrix protein fibulin-1 is upregulated in the arterial wall in type 2 diabetes (T2D) and circulates in increased concentrations in diabetes. Metformin is an antidiabetic drug with beneficial cardiovascular disease effects in diabetes. We hypothesized that metformin would influence the increased level of plasma fibulin-1 in diabetes. RESEARCH DESIGN AND METHODS After a 4-week run-in period, 371 eligible patients with T2D were randomized to treatment groups in a factorial design including insulin alone (control), +metformin, +rosiglitazone, or +both metformin and rosiglitazone. Plasma fibulin-1 was analyzed at the beginning of the study and after 18 and 24 months. RESULTS Plasma fibulin-1 increased in all groups throughout the 2-year period; however, the increase was strongly attenuated among patients treated with metformin. A highly significant difference was observed when the mean change in plasma fibulin-1 was compared between metformin- and non-metformin-treated individuals both at 18 and 24 months of treatment, but rosiglitazone had no effect. Metformin and rosiglitazone alone reduced the HbA1c levels to comparable levels and in combination even further. CONCLUSIONS Metformin attenuates the increase in plasma fibulin-1 concentrations in T2D, independently of glycemic effects. Changes in fibulin-1 may reflect an important element in diabetic arteriopathy that can be influenced by metformin.
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Affiliation(s)
- Vibe Skov
- Corresponding author: Lars M. Rasmussen,
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12
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Something old, something new and something borrowed: emerging paradigm of insulin-like growth factor type 1 receptor (IGF-1R) signaling regulation. Cell Mol Life Sci 2013; 71:2403-27. [PMID: 24276851 PMCID: PMC4055838 DOI: 10.1007/s00018-013-1514-y] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 10/17/2013] [Accepted: 11/07/2013] [Indexed: 12/14/2022]
Abstract
The insulin-like growth factor type 1 receptor (IGF-1R) plays a key role in the development and progression of cancer; however, therapeutics targeting it have had disappointing results in the clinic. As a receptor tyrosine kinase (RTK), IGF-1R is traditionally described as an ON/OFF system, with ligand stabilizing the ON state and exclusive kinase-dependent signaling activation. Newly added to the traditional model, ubiquitin-mediated receptor downregulation and degradation was originally described as a response to ligand/receptor interaction and thus inseparable from kinase signaling activation. Yet, the classical model has proven over-simplified and insufficient to explain experimental evidence accumulated over the last decade, including kinase-independent signaling, unbalanced signaling, or dissociation between signaling and receptor downregulation. Based on the recent findings that IGF-1R “borrows” components of G-protein coupled receptor (GPCR) signaling, including β-arrestins and G-protein-related kinases, we discuss the emerging paradigm for the IGF-1R as a functional RTK/GPCR hybrid, which integrates the kinase signaling with the IGF-1R canonical GPCR characteristics. The contradictions to the classical IGF-1R signaling concept as well as the design of anti-IGF-1R therapeutics treatment are considered in the light of this paradigm shift and we advocate recognition of IGF-1R as a valid target for cancer treatment.
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Rapraeger AC. Synstatin: a selective inhibitor of the syndecan-1-coupled IGF1R-αvβ3 integrin complex in tumorigenesis and angiogenesis. FEBS J 2013; 280:2207-15. [PMID: 23375101 DOI: 10.1111/febs.12160] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 01/24/2013] [Accepted: 01/28/2013] [Indexed: 01/31/2023]
Abstract
The syndecans are a family of heparan sulfate-decorated cell-surface proteoglycans: matrix receptors with roles in cell adhesion and growth factor signaling. Their heparan sulfate chains recognize 'heparin-binding' motifs that are ubiquitously present in the extracellular matrix, providing the means for syndecans to constitutively bind and cluster to sites of cell-matrix adhesion. Emerging evidence suggests that specialized docking sites in the syndecan extracellular domains may serve to localize other receptors to these sites as well, including integrins and growth factor receptor tyrosine kinases. A prototype of this mechanism is capture of the αvβ3 integrin and insulin-like growth factor 1 receptor (IGF1R) by syndecan-1 (Sdc1), forming a ternary receptor complex in which signaling downstream of IGF1R activates the integrin. This Sdc1-coupled ternary receptor complex is especially prevalent on tumor cells and activated endothelial cells undergoing angiogenesis, reflecting the up-regulated expression of αvβ3 integrin in such cells. As such, much effort has focused on developing therapeutic agents that target this integrin in various cancers. Along these lines, the site in the Sdc1 ectodomain that is responsible for capture and activation of the αvβ3 or αvβ5 integrins by IGF1R can be mimicked by a short peptide called 'synstatin', which competitively displaces the integrin and IGF1R kinase from the syndecan and inactivates the complex. This review summarizes our current knowledge of the Sdc1-coupled ternary receptor complex and the efficacy of synstatin as an emerging therapeutic agent to target this signaling mechanism.
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Affiliation(s)
- Alan C Rapraeger
- Department of Human Oncology, Carbone Comprehensive Cancer Center, Wisconsin Institutes for Medical Research, University of Wisconsin-Madison, Madison, WI 53705, USA.
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14
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Rapraeger AC, Ell BJ, Roy M, Li X, Morrison OR, Thomas GM, Beauvais DM. Vascular endothelial-cadherin stimulates syndecan-1-coupled insulin-like growth factor-1 receptor and cross-talk between αVβ3 integrin and vascular endothelial growth factor receptor 2 at the onset of endothelial cell dissemination during angiogenesis. FEBS J 2013; 280:2194-206. [PMID: 23331867 DOI: 10.1111/febs.12134] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 01/05/2013] [Accepted: 01/11/2013] [Indexed: 12/23/2022]
Abstract
Vascular endothelial growth factor (VEGF)-stimulated angiogenesis depends on a cross-talk mechanism involving VEGF receptor 2 (VEGFR2), vascular endothelial (VE)-cadherin and the αVβ3 integrin. Because we have shown that αVβ3 integrin activation is dependent on its incorporation, along with the insulin-like growth factor-1 receptor (IGF1R) kinase, into a ternary receptor complex organized by the matrix receptor syndecan-1 (Sdc1), we questioned the role of this core complex in VEGF-stimulated angiogenesis. We find that the Sdc1-coupled ternary receptor complex is required for VEGF signalling and for stimulation of vascular endothelial cell migration by vascular endothelial cadherin (VE-cadherin) engagement. VE-cadherin binding to Fc/VE-cadherin extracellular domain chimera activates Sdc1-coupled IGF1R and αvβ3 integrin; this depends on VEGFR2 and c-Src activated by the cadherin. Blocking homotypic VE-cadherin engagement disrupts VEGF-stimulated cell migration, which is restored by clustering the cadherin in the absence of cell-cell adhesion. This cadherin-dependent stimulation requires VEGFR2 and IGF1R and is blocked by synstatin (SSTN)(92-119), a peptide that competitively disrupts the Sdc1-coupled ternary complex and prevents the αVβ3 integrin activation required for VEGFR2 activation. VEGFR2-stimulated angiogenesis in the mouse aortic ring explant assay is disrupted by SSTN, although only early in the process, suggesting that IGF1R coupling to Sdc1 and αVβ3 integrin comprises a core activation mechanism activated by VE-cadherin that is necessary for VEGFR2 and integrin activation in the initial stages of endothelial cell dissemination during angiogenesis.
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Affiliation(s)
- Alan C Rapraeger
- Department of Human Oncology, University of Wisconsin-Madison, WI 53705, USA.
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15
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Abstract
The increasing percentage of obese individuals in the population and its independent association of increased risk for the development of cancer have heightened the necessity to understand the molecular mechanisms that underlie this connection. The deregulation of adipokines in the setting of obesity and their impact on cancer progression and metastasis is one such area of research. Adipokines are bioactive proteins that mediate metabolism, inflammation, angiogenesis, and proliferation. Altered levels of adipokines or their cognate receptors in cancers can ultimately lead to an imbalance in downstream molecular pathways. Discovery of adipokine receptors in various cancers has highlighted the potential for novel therapeutic targets. Leptin and adiponectin represent two adipokines that elicit generally opposing molecular effects. Epidemiologic studies have highlighted associations between increased serum leptin levels and increased tumor growth, whereas adiponectin exhibits an inverse correlation with cancer development. This review addresses the current level of understanding of molecular pathways activated by adiponectin and leptin to identify the areas of intervention and facilitate advancement in the field.
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Affiliation(s)
- Michael N Vansaun
- Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
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Fujita M, Takada YK, Takada Y. Insulin-like growth factor (IGF) signaling requires αvβ3-IGF1-IGF type 1 receptor (IGF1R) ternary complex formation in anchorage independence, and the complex formation does not require IGF1R and Src activation. J Biol Chem 2012; 288:3059-69. [PMID: 23243309 DOI: 10.1074/jbc.m112.412536] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin αvβ3 plays a role in insulin-like growth factor 1 (IGF1) signaling (integrin-IGF1 receptor (IGF1R) cross-talk) in non-transformed cells in anchorage-dependent conditions. We reported previously that IGF1 directly binds to αvβ3 and induces αvβ3-IGF1-IGF1R ternary complex formation in these conditions. The integrin-binding defective IGF1 mutant (R36E/R37E) is defective in inducing ternary complex formation and IGF signaling, whereas it still binds to IGF1R. We studied if IGF1 can induce signaling in anchorage-independent conditions in transformed Chinese hamster ovary cells that express αvβ3 (β3-CHO) cells. Here we describe that IGF1 signals were more clearly detectable in anchorage-independent conditions (polyHEMA-coated plates) than in anchorage-dependent conditions. This suggests that IGF signaling is masked by signals from cell-matrix interaction in anchorage-dependent conditions. IGF signaling required αvβ3 expression, and R36E/R37E was defective in inducing signals in polyHEMA-coated plates. These results suggest that αvβ3-IGF1 interaction, not αvβ3-extracellular matrix interaction, is essential for IGF signaling. Inhibitors of IGF1R, Src, AKT, and ERK1/2 did not suppress αvβ3-IGF-IGF1R ternary complex formation, suggesting that activation of these kinases are not required for ternary complex formation. Also, mutations of the β3 cytoplasmic tail (Y747F and Y759F) that block β3 tyrosine phosphorylation did not affect IGF1R phosphorylation or AKT activation. We propose a model in which IGF1 binding to IGF1R induces recruitment of integrin αvβ3 to the IGF-IGF1R complex and then β3 and IGF1R are phosphorylated. It is likely that αvβ3 should be together with the IGF1-IGF1R complex for triggering IGF signaling.
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Affiliation(s)
- Masaaki Fujita
- Department of Dermatology, University of California Davis School of Medicine, Sacramento, California 95817, USA
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17
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Novel role for SHP-2 in nutrient-responsive control of S6 kinase 1 signaling. Mol Cell Biol 2012; 33:293-306. [PMID: 23129808 DOI: 10.1128/mcb.01285-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Amino acids are required for the activation of the mammalian target of rapamycin complex 1 (mTORC1), which plays a critical role in cell growth, proliferation, and metabolism. The branched-chain amino acid leucine is an essential nutrient that stimulates mTORC1 to promote protein synthesis by activating p70 S6 kinase 1 (S6K1). Here we show that the protein tyrosine phosphatase SHP-2 is required for leucine-induced activation of S6K1 in skeletal myoblasts. In response to leucine, S6K1 activation is inhibited in myoblasts either lacking SHP-2 expression or overexpressing a catalytically inactive mutant of SHP-2. Activation of S6K1 by leucine requires the mobilization of intracellular calcium (Ca(2+)), which we show is mediated by SHP-2 in an inositol-1,4,5-trisphosphate-dependent manner. Ectopic Ca(2+) mobilization rescued the S6K1 activation defect in SHP-2-deficient myoblasts. SHP-2 was identified to act upstream of phospholipase C β4, linking it to the generation of nutrient-induced Ca(2+) release and S6K1 phosphorylation. Consistent with these results, SHP-2-deficient myoblasts exhibited impaired leucine sensing, leading to defective autophagy and reduced myoblast size. These data define a new role for SHP-2 as a nutrient-sensing regulator in skeletal myoblasts that is required for the activation of S6K1.
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Geier F, Fengos G, Iber D. A computational analysis of the dynamic roles of talin, Dok1, and PIPKI for integrin activation. PLoS One 2011; 6:e24808. [PMID: 22110576 PMCID: PMC3217926 DOI: 10.1371/journal.pone.0024808] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 08/22/2011] [Indexed: 12/12/2022] Open
Abstract
Integrin signaling regulates cell migration and plays a pivotal role in developmental processes and cancer metastasis. Integrin signaling has been studied extensively and much data is available on pathway components and interactions. Yet the data is fragmented and an integrated model is missing. We use a rule-based modeling approach to integrate available data and test biological hypotheses regarding the role of talin, Dok1 and PIPKI in integrin activation. The detailed biochemical characterization of integrin signaling provides us with measured values for most of the kinetics parameters. However, measurements are not fully accurate and the cellular concentrations of signaling proteins are largely unknown and expected to vary substantially across different cellular conditions. By sampling model behaviors over the physiologically realistic parameter range we find that the model exhibits only two different qualitative behaviors and these depend mainly on the relative protein concentrations, which offers a powerful point of control to the cell. Our study highlights the necessity to characterize model behavior not for a single parameter optimum, but to identify parameter sets that characterize different signaling modes.
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Affiliation(s)
- Florian Geier
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Basel, Switzerland
| | - Georgios Fengos
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Basel, Switzerland
| | - Dagmar Iber
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Basel, Switzerland
- * E-mail:
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Rangaswami H, Schwappacher R, Marathe N, Zhuang S, Casteel DE, Haas B, Chen Y, Pfeifer A, Kato H, Shattil S, Boss GR, Pilz RB. Cyclic GMP and protein kinase G control a Src-containing mechanosome in osteoblasts. Sci Signal 2010; 3:ra91. [PMID: 21177494 DOI: 10.1126/scisignal.2001423] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mechanical stimulation is crucial for bone growth and remodeling, and fluid shear stress promotes anabolic responses in osteoblasts through multiple second messengers, including nitric oxide (NO). NO triggers production of cyclic guanosine 3',5'-monophosphate (cGMP), which in turn activates protein kinase G (PKG). We found that the NO-cGMP-PKG signaling pathway activates Src in mechanically stimulated osteoblasts to initiate a proliferative response. PKGII was necessary for Src activation, a process that also required the interaction of Src with β₃ integrins and dephosphorylation of Src by a complex containing the phosphatases SHP-1 (Src homology 2 domain-containing tyrosine phosphatase 1) and SHP-2. PKGII directly phosphorylated and stimulated SHP-1 activity, and fluid shear stress triggered the recruitment of PKGII, Src, SHP-1, and SHP-2 to a mechanosome containing β₃ integrins. PKGII-null mice showed defective Src and ERK (extracellular signal-regulated kinase) signaling in osteoblasts and decreased ERK-dependent gene expression in bone. Our findings reveal a convergence of NO-cGMP-PKG and integrin signaling and establish a previously unknown mechanism of Src activation. These results support the use of PKG-activating drugs to mimic the anabolic effects of mechanical stimulation of bone in the treatment of osteoporosis.
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Affiliation(s)
- Hema Rangaswami
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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20
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Régent M, Planus E, Bouin AP, Bouvard D, Brunner M, Faurobert E, Millon-Frémillon A, Block MR, Albiges-Rizo C. Specificities of β1 integrin signaling in the control of cell adhesion and adhesive strength. Eur J Cell Biol 2010; 90:261-9. [PMID: 20971526 DOI: 10.1016/j.ejcb.2010.09.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 09/01/2010] [Accepted: 09/02/2010] [Indexed: 11/26/2022] Open
Abstract
Cells exert actomyosin contractility and cytoskeleton-dependent force in response to matrix stiffness cues. Cells dynamically adapt to force by modifying their behavior and remodeling their microenvironment. This adaptation is favored by integrin activation switch and their ability to modulate their clustering and the assembly of an intracellular hub in response to force. Indeed integrins are mechanoreceptors and mediate mechanotransduction by transferring forces to specific adhesion proteins into focal adhesions which are sensitive to tension and activate intracellular signals. α(5)β(1) integrin is considered of major importance for the formation of an elaborate meshwork of fibronectin fibrils and for the extracellular matrix deposition and remodeling. Here we summarize recent progress in the study of mechanisms regulating the activation cycle of β(1) integrin and the specificity of α(5)β(1) integrin in mechanotransduction.
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Affiliation(s)
- Myriam Régent
- INSERM U823 Institut Albert Bonniot, Université Joseph Fourier, France
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21
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Kandadi MR, Stratton MS, Ren J. The role of Src homology 2 containing protein tyrosine phosphatase 2 in vascular smooth muscle cell migration and proliferation. Acta Pharmacol Sin 2010; 31:1277-83. [PMID: 20871619 DOI: 10.1038/aps.2010.168] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vascular smooth muscle cells (VSMCs) perform essential smooth muscle contractile and synthetic functions including migration, differentiation and proliferation under physiological and pathological conditions. In response to pathological stimuli, VMSCs undergo phenotypic change resulting in abnormal migration and proliferation, which may contribute to a "pathogenesis-like" atherosclerosis. Intracellular signaling mechanisms governing this phenotypic switch are of great significance not only for better understanding of atherosclerotic plaque formation but also for strategy for pertinent therapeutic remedies. Src Homology 2 Containing Protein Tyrosine Phosphatase 2 (SHP2) is a ubiquitous tyrosine phosphatase containing Src Homology 2 domains which plays major biological functions in response to various growth factors, hormones or cytokines. In particular, SHP2 is implicated in cell signaling pathways controlling cell cycle progression, growth and migration. In this review we will mainly discuss the recent literature demonstrating the role of SHP2 in VSMC migration and proliferation.
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22
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Beattie J, McIntosh L, van der Walle CF. Cross-talk between the insulin-like growth factor (IGF) axis and membrane integrins to regulate cell physiology. J Cell Physiol 2010; 224:605-11. [PMID: 20432472 DOI: 10.1002/jcp.22183] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The biology of cross-talk between activated growth factor receptors and cell-surface integrins is an area which has attracted much interest in recent years (Schwartz and Ginsberg, 2002). This review discusses the relationship between the insulin-like growth factor (IGF) axis and cell-surface integrin receptors in the regulation of various aspects of cell physiology. Key to these interactions are signals transmitted between integrins and the IGF-I receptor (IGF-IR) when either or both are bound to their cognate ligands and we will review the current state of knowledge in this area. The IGF axis comprises many molecular components and we will also discuss the potential role of these species in cross-talk with the integrin receptor. With respect to integrin ligands, we will mainly focus on the well-characterized interactions of the two extracellular matrix (ECM) glycoproteins fibronectin (FN) and vitronectin (VN) with cell-surface ligands, and, how this affects activity through the IGF axis. However, we will also highlight the importance of other integrin activation mechanisms and their impact on IGF activity.
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Affiliation(s)
- James Beattie
- Department of Oral Biology, Leeds Dental Institute, University of Leeds, Leeds, UK.
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23
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Glucose regulation of thrombospondin and its role in the modulation of smooth muscle cell proliferation. EXPERIMENTAL DIABETES RESEARCH 2010; 2010. [PMID: 20689700 PMCID: PMC2905704 DOI: 10.1155/2010/617052] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 04/05/2010] [Accepted: 04/16/2010] [Indexed: 11/17/2022]
Abstract
Smooth muscle cells (SMC) maintained in high glucose are more responsive to IGF-I than those in normal glucose. There is significantly more thrombospondin-1 (TSP-1) in extracellular matrix surrounding SMC grown in 25 mM glucose. In this study we investigated 1) the mechanism by which glucose regulates TSP-1 levels and 2) the mechanism by which TS-1 enhances IGF-I signaling. The addition of TSP-1 to primary SMC was sufficient to enhance IGF-I responsiveness in normal glucose. Reducing TSP-1 protein levels inhibited IGF-I signaling in SMC maintained in high glucose. We determined that TSP-1 protected IAP/CD47 from cleavage and thereby facilitated its association with SHP substrate-1 (SHPS-1). We have shown previously that the hyperglycemia induced protection of IAP from cleavage is an important component of the ability of hyperglycemia to enhance IGF-I signaling. Furthermore we determined that TSP-1 also enhanced phosphorylation of the beta3 subunit of the alphaVbeta3 integrin, another molecular event that we have shown are critical for SMC response to IGF-I in high glucose. Our studies also revealed that the difference in the amount of TSP-1 in the two different glucose conditions was due, at least in part, to a difference in the cellular uptake and degradation of TSP-1.
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Anthis NJ, Haling JR, Oxley CL, Memo M, Wegener KL, Lim CJ, Ginsberg MH, Campbell ID. Beta integrin tyrosine phosphorylation is a conserved mechanism for regulating talin-induced integrin activation. J Biol Chem 2009; 284:36700-36710. [PMID: 19843520 PMCID: PMC2794784 DOI: 10.1074/jbc.m109.061275] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 10/09/2009] [Indexed: 01/04/2023] Open
Abstract
Integrins are large membrane-spanning receptors fundamental to cell adhesion and migration. Integrin adhesiveness for the extracellular matrix is activated by the cytoskeletal protein talin via direct binding of its phosphotyrosine-binding-like F3 domain to the cytoplasmic tail of the beta integrin subunit. The phosphotyrosine-binding domain of the signaling protein Dok1, on the other hand, has an inactivating effect on integrins, a phenomenon that is modulated by integrin tyrosine phosphorylation. Using full-length tyrosine-phosphorylated (15)N-labeled beta3, beta1A, and beta7 integrin tails and an NMR-based protein-protein interaction assay, we show that talin1 binds to the NPXY motif and the membrane-proximal portion of beta3, beta1A, and beta7 tails, and that the affinity of this interaction is decreased by integrin tyrosine phosphorylation. Dok1 only interacts weakly with unphosphorylated tails, but its affinity is greatly increased by integrin tyrosine phosphorylation. The Dok1 interaction remains restricted to the integrin NPXY region, thus phosphorylation inhibits integrin activation by increasing the affinity of beta integrin tails for a talin competitor that does not form activating membrane-proximal interactions with the integrin. Key residues governing these specificities were identified by detailed structural analysis, and talin1 was engineered to bind preferentially to phosphorylated integrins by introducing the mutation D372R. As predicted, this mutation affects talin1 localization in live cells in an integrin phosphorylation-specific manner. Together, these results indicate that tyrosine phosphorylation is a common mechanism for regulating integrin activation, despite subtle differences in how these integrins interact with their binding proteins.
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Affiliation(s)
- Nicholas J Anthis
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093.
| | - Jacob R Haling
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Camilla L Oxley
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093
| | - Massimiliano Memo
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093
| | - Kate L Wegener
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093
| | - Chinten J Lim
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Mark H Ginsberg
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Iain D Campbell
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093.
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The metal-binding domain of IGFBP-3 selectively delivers therapeutic molecules into cancer cells. Anticancer Drugs 2009; 20:21-31. [PMID: 19342998 DOI: 10.1097/cad.0b013e3283144610] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Conventional chemotherapy for cancer has limited specificity for cancer cells. Here, we investigate the possibility of improving the selectivity of chemotherapy by coadministering targeted biological modifier peptides. We show that the 22-amino acid metal-binding transporter domain (MBD) derived from insulin-like growth factor-binding protein-3 selectively targets cancer cells. The rate of MBD uptake by cells was measured using a panel of 54 human cancer cell lines and correlated with MBD cross-linking to cell surface transferrin receptor, caveolin 1, and integrin beta. Gene array data show that MBD uptake correlates with the expression of genes associated with cellular stress-coping mechanisms commonly upregulated in cancer (nuclear factor-kappaB, Hsp-70B). MBD-tagged peptides designed to inhibit such mechanisms have cytotoxic effects on a broad range of human cancer cell lines. The discriminant validity of these peptides as potential cotherapeutic agents was investigated by comparing their cytotoxicity to cancer cell lines versus normal human cell counterparts. Synergies between these peptides and marginally cytotoxic levels of 5-fluorouracil were demonstrated. Biodistribution data from in-vivo experiments in mice and rats confirm that MBD-tagged peptides and proteins preferably localize to specific tissues, such as kidney and pancreas. Intracardial injection of CCRF-CEM T-cell leukemia or MDA-MB-435 cells into Rag-2 mice establishes disseminated disease within 7 days. Twenty-five-day subcutaneous administration of a three-peptide cocktail (3 mg/kg) in combination with 5-fluorouracil in Rag-2 mice with established CCRF-CEM leukemia significantly reduces splenomegaly and bone marrow cancer cell burden. In a similar experiment using MDA-MB-435 cells, MBD-tagged peptides reduced human cell burden in bone marrow. Taken together, these data suggest that MBD-tagged molecules can be used as highly selective chemosensitizers in the treatment of hematological and disseminated malignancies.
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26
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Somanath PR, Malinin NL, Byzova TV. Cooperation between integrin alphavbeta3 and VEGFR2 in angiogenesis. Angiogenesis 2009; 12:177-85. [PMID: 19267251 DOI: 10.1007/s10456-009-9141-9] [Citation(s) in RCA: 188] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 02/16/2009] [Indexed: 11/30/2022]
Abstract
The cross-talk between receptor tyrosine kinases and integrin receptors are known to be crucial for a number of cellular functions. On endothelial cells, an interaction between integrin alphavbeta3 and VEGFR2 seems to be particularly important process during vascularization. Importantly, the functional association between VEGFR2 and integrin alphavbeta3 is of reciprocal nature since each receptor is able to promote activation of its counterpart. This mutually beneficial relationship regulates a number of cellular activities involved in angiogenesis, including endothelial cell migration, survival and tube formation, and hematopoietic cell functions within vasculature. This article discusses several possible mechanisms reported by different labs which mediate formation of the complex between VEGFR-2 and alphavbeta3 on endothelial cells. The pathological consequences and regulatory events involved in this receptor cross-talk are also presented.
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Affiliation(s)
- Payaningal R Somanath
- Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Department of Molecular Cardiology, NB50, Lerner Research Institute, The Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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27
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Maile LA, Aday AW, Busby WH, Sanghani R, Veluvolu U, Clemmons DR. Modulation of integrin antagonist signaling by ligand binding of the heparin-binding domain of vitronectin to the alphaVbeta3 integrin. J Cell Biochem 2009; 105:437-46. [PMID: 18615592 DOI: 10.1002/jcb.21841] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The interaction between the arginine glycine and aspartic acid motif (RGD) of integrin ligands such as vitronectin and the integrin receptor alphaVbeta3 in mediating cell attachment has been well described. Similarly, the ability of disintegrins, small RGD containing peptides, to inhibit cell attachment and other cellular processes has also been studied extensively. Recently, we characterized a second site of interaction between vitronectin and its integrin partner. We determined that amino acids within the heparin-binding domain of vitronectin bind to a cysteine loop (C-loop) region of beta3 and that this interaction is required for the positive effects of alphaVbeta3 ligand occupancy on IGF-I signaling in smooth muscle cells. In this study we examine the signaling events activated following ligand binding of disintegrins to the alphaVbeta3 and the ability of these signals to be regulated by binding of the heparin-binding domain of vitronectin. We demonstrate that disintegrin ligand binding activates a series of events including the sequential activation of the tyrosine kinases c-Src and Syk. This leads to the activation of calpain and the cleavage of the beta3 cytoplasmic tail. Addition of vitronectin or a peptide homologous to the heparin-binding domain inhibited activation of this pathway. Our results suggest that the signaling events that occur following ligand binding to the alphaVbeta3 integrin reflects a balance between the effects mediated through the RGD binding site interaction and the effects mediated by the heparin binding site interaction and that for intact vitronectin the effect of the heparin-binding domain predominates.
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Affiliation(s)
- Laura A Maile
- Division of Endocrinology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7170, USA.
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Perrini S, Natalicchio A, Laviola L, Cignarelli A, Melchiorre M, De Stefano F, Caccioppoli C, Leonardini A, Martemucci S, Belsanti G, Miccoli S, Ciampolillo A, Corrado A, Cantatore FP, Giorgino R, Giorgino F. Abnormalities of insulin-like growth factor-I signaling and impaired cell proliferation in osteoblasts from subjects with osteoporosis. Endocrinology 2008; 149:1302-13. [PMID: 18079194 DOI: 10.1210/en.2007-1349] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IGF-I regulates bone acquisition and maintenance, even though the cellular targets and signaling pathways responsible for its action in human bone cells are poorly understood. Whether abnormalities in IGF-I action and signaling occur in human osteoblasts under conditions of net bone loss has not been determined. Herein we carried out a comparative analysis of IGF-I signaling in primary cultures of human osteoblasts from osteoporotic and control donors. In comparison with control cells, osteoporotic osteoblasts showed increased tyrosine phosphorylation of the IGF-I receptor in the basal state and blunted stimulation of receptor phosphorylation by IGF-I. Augmentation of basal IGF-I receptor phosphorylation was associated with coordinate increases in basal tyrosine phosphorylation of insulin receptor substrate (IRS)-2 and activation of Erk, which were also minimally responsive to IGF-I stimulation. By contrast, phosphorylation levels of IRS-1, Akt, and glycogen synthase kinase-3 were similar in the basal state in control and osteoporotic osteoblasts and showed marked increases after IGF-I stimulation in both cell populations, even though these responses were significantly lower in the osteoporotic osteoblasts. The IGF-I signaling abnormalities in osteoporotic osteoblasts were associated with reduced DNA synthesis both under basal conditions and after stimulation with IGF-I. Interestingly, treatment of the osteoporotic osteoblasts with the MAPK kinase inhibitor PD098059 reduced the elevated levels of Erk phosphorylation and increased basal DNA synthesis. Collectively, our data show that altered osteoblast proliferation in human osteoporosis may result from dysregulation of IGF-I receptor signaling, including constitutive activation of the IRS-2/Erk signaling pathway, which becomes unresponsive to IGF-I, and defective induction of the IRS-1/Akt signaling pathway.
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Affiliation(s)
- Sebastio Perrini
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, and Metabolic Diseases, University of Bari, Piazza Giulio Cesare, 11, I-70124 Bari, Italy
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Oxley CL, Anthis NJ, Lowe ED, Vakonakis I, Campbell ID, Wegener KL. An integrin phosphorylation switch: the effect of beta3 integrin tail phosphorylation on Dok1 and talin binding. J Biol Chem 2007; 283:5420-6. [PMID: 18156175 DOI: 10.1074/jbc.m709435200] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrins play a fundamental role in cell migration and adhesion; knowledge of how they are regulated and controlled is vital for understanding these processes. Recent work showed that Dok1 negatively regulates integrin activation, presumably by competition with talin. To understand how this occurs, we used NMR spectroscopy and x-ray crystallography to investigate the molecular details of interactions with integrins. The binding affinities of beta3 integrin tails for the Dok1 and talin phosphotyrosine binding domains were quantified using 15N-1H hetero-nuclear single quantum correlation titrations, revealing that the unphosphorylated integrin tail binds more strongly to talin than Dok1. Chemical shift mapping showed that unlike talin, Dok1 exclusively interacts with the canonical NPXY motif of the beta3 integrin tail. Upon phosphorylation of Tyr 747 in the beta3 integrin tail, however, Dok1 then binds much more strongly than talin. Thus, we show that phosphorylation of Tyr 747 provides a switch for integrin ligand binding. This switch may represent an in vivo mechanism for control of integrin receptor activation. These results have implications for the control of integrin signaling by proteins containing phosphotyrosine binding domains.
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Affiliation(s)
- Camilla L Oxley
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
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30
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Integrin Regulation of the IGF-I Receptor in Bone, and the Response to Load. Clin Rev Bone Miner Metab 2007. [DOI: 10.1007/s12018-008-9009-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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31
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Dozmorov MG, Kropp BP, Hurst RE, Cheng EY, Lin HK. Differentially expressed gene networks in cultured smooth muscle cells from normal and neuropathic bladder. J Smooth Muscle Res 2007; 43:55-72. [PMID: 17598958 DOI: 10.1540/jsmr.43.55] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neuropathic bladder dysfunction results from abnormal development of the spine, spinal cord injuries, or diseases such as diabetics. Patients with neuropathic bladders often require surgical intervention such as bladder reconstruction to improve incontinence and prevent renal damage. Tissue engineering with ex-vivo cultured bladder cells has been suggested as one means for improving bladder function. However, we previously demonstrated that cultured bladder smooth muscle cells (SMCs) derived from neuropathic bladder exhibit and maintain altered pathologic phenotypes in culture. To identify genes that are responsible for the abnormal neuropathic phenotypes specifically elevated cell proliferation, the expression levels of 1,185 genes were compared between cultured SMCs derived from normal and neuropathic bladders using a cDNA array consisting of well-annotated genes. The expression data were analyzed using several methods to identify differentially expressed genes. The resulting sets of differentially expressed genes were examined by pathway analysis to identify the networks that remain abnormal in the culture-stable phenotype of neuropathic SMCs. A total of 18 genes that are differentially expressed between cultured normal and neuropathic bladder SMCs were identified. Of these 17 were up-regulated greater than 2-fold in neuropathic bladder SMCs, six of them along with one gene that was not up-regulated greater than 2-fold in cultured neuropathic bladder SMCs were confirmed and identified by more stringent analysis methods including significance analysis of microarrays, class comparison, and class prediction analyses. The major dysregulated pathways include fibroblast growth factor signaling, PTEN signaling, and integrin signaling. Our results further suggest that altered neuropathic bladder SMC phenotypes is stable in the culture environments and that SMCs derived from diseased bladders may not be appropriate for tissue engineering purpose without modification of pathologically altered genes expression.
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Affiliation(s)
- Mikhail G Dozmorov
- Department of Urology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73034, USA
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Clemmons DR, Maile LA, Ling Y, Yarber J, Busby WH. Role of the integrin alphaVbeta3 in mediating increased smooth muscle cell responsiveness to IGF-I in response to hyperglycemic stress. Growth Horm IGF Res 2007; 17:265-270. [PMID: 17412627 PMCID: PMC2366026 DOI: 10.1016/j.ghir.2007.01.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Under usual conditions, the role of IGF-I in vascular cell types is to maintain cellular protein synthesis and cell size, and even excess IGF-I does not stimulate proliferation. In pathophysiologic states, such as hyperglycemia, smooth muscle cells (SMC) dedifferentiate and change their responsiveness to IGF-I. During hyperglycemia IGF-I stimulates both SMC migration and proliferation. Our laboratory has investigated the molecular mechanism by which this change is mediated. During hyperglycemia SMC secrete increased concentrations of thrombospondin, vitronectin and osteopontin, ligands for the integrin alphaVbeta3. Activation of alphaVbeta3 stimulates recruitment of a tyrosine phosphatase, SHP-2. Exposure of SMC to IGF-I results in phosphorylation of the transmembrane protein, SHPS-1, which provides a docking site for alphaVbeta3-associated SHP-2. After IGF-I stimulation SHP-2 associates with Src kinase, which associates with the signaling protein Shc. Src phosphorylates Shc, resulting in activation of MAP kinases, which are necessary both for stimulation of cell proliferation and migration. Blocking activation of alphaVbeta3 results in an inability of IGF-I to stimulate Shc phosphorylation. Under conditions of normoglycemia, there are insufficient alphaVbeta3 ligands to recruit SHP-2, and no increase in Shc phosphorylation can be demonstrated in SMC. In contrast, if alphaVbeta3 ligands are added to cells in normal glucose, the signaling events that are necessary for Shc phosphorylation can be reconstituted. Therefore when SMC are exposed to normal glucose they are protected from excessive stimulation of mitogenesis by IGF-I. With hyperglycemia there is a marked increased in alphaVbeta3 ligands and Shc phosphorylation in response to IGF-I is sustained. These findings indicate that in SMC hyperglycemic stress leads to altered IGF-I signaling, which allows the cells to undergo a mitogenic response, and which may contribute to the development of atherosclerosis.
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Affiliation(s)
- David R Clemmons
- Department of Medicine, Division of Endocrinology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599, USA.
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Edderkaoui M, Hong P, Lee JK, Pandol SJ, Gukovskaya AS. Insulin-like growth factor-I receptor mediates the prosurvival effect of fibronectin. J Biol Chem 2007; 282:26646-26655. [PMID: 17627944 DOI: 10.1074/jbc.m702836200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We recently showed that extracellular matrix (ECM) proteins, which are abundant in desmoplastic pancreatic tumor, are as potent as growth factors in inhibiting apoptosis in pancreatic cancer (PaCa) cells. Here we show that fibronectin, a major ECM component, engages insulin-like growth factor-I receptor (IGF-IR) to inhibit PaCa cell death. We found that fibronectin-induced protection from apoptosis is fully mediated by IGF-IR and is independent of IGF-I. Pharmacologic and molecular inhibitions of IGF-IR stimulated apoptosis and prevented the prosurvival effect of fibronectin in PaCa cells. Our data indicate that fibronectin protects from apoptosis through trans-activation of IGF-IR. We showed that fibronectin stimulated complex formation between its receptor beta3 integrin and protein-tyrosine phosphatase SHP-2. This process of complex formation, in turn, prevents SHP-2 from dephosphorylating IGF-IR resulting in sustained phosphorylation of IGF-IR and leading to the downstream activation of Akt kinase, up-regulation of antiapoptotic Bcl(xL), and inhibition of apoptosis. Among ECM proteins tested only fibronectin and laminin but not vitronectin and collagen I stimulated trans-activation of IGF-IR. Interaction of fibronectin with beta3 but not beta1 integrin receptors mediates the survival pathway. In contrast, fibronectin-induced adhesion is mediated through beta1 integrin receptor and is IGF-IR-independent. Thus, our results indicate that the prosurvival effect of fibronectin in PaCa cells is mediated by trans-activation of IGF-IR induced by the beta3 integrin receptor. The data suggest IGF-IR as a key target for prevention of the prosurvival effects of ECM proteins and growth factors in pancreatic cancer.
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Affiliation(s)
- Mouad Edderkaoui
- Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and University of California, Los Angeles, California 90073
| | - Peggy Hong
- Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and University of California, Los Angeles, California 90073
| | - Jong K Lee
- School of Medicine, Sungkyunkwan University, Seoul 135-710, Korea
| | - Stephen J Pandol
- Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and University of California, Los Angeles, California 90073
| | - Anna S Gukovskaya
- Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and University of California, Los Angeles, California 90073.
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Tyrosine phosphatases such as SHP-2 act in a balance with Src-family kinases in stabilization of postsynaptic clusters of acetylcholine receptors. BMC Neurosci 2007; 8:46. [PMID: 17605785 PMCID: PMC1924855 DOI: 10.1186/1471-2202-8-46] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Accepted: 07/02/2007] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Development of neural networks requires that synapses are formed, eliminated and stabilized. At the neuromuscular junction (NMJ), agrin/MuSK signaling, by triggering downstream pathways, causes clustering and phosphorylation of postsynaptic acetylcholine receptors (AChRs). Postnatally, AChR aggregates are stabilized by molecular pathways that are poorly characterized. Gain or loss of function of Src-family kinases (SFKs) disassembles AChR clusters at adult NMJs in vivo, whereas AChR aggregates disperse rapidly upon withdrawal of agrin from cultured src-/-;fyn-/- myotubes. This suggests that a balance between protein tyrosine phosphatases (PTPs) and protein tyrosine kinases (PTKs) such as those of the Src-family may be essential in stabilizing clusters of AChRs. RESULTS We have analyzed the role of PTPs in maintenance of AChR aggregates, by adding and then withdrawing agrin from cultured myotubes in the presence of PTP or PTK inhibitors and quantitating remaining AChR clusters. In wild-type myotubes, blocking PTPs with pervanadate caused enhanced disassembly of AChR clusters after agrin withdrawal. When added at the time of agrin withdrawal, SFK inhibitors destabilized AChR aggregates but concomitant addition of pervanadate rescued cluster stability. Likewise in src-/-;fyn-/- myotubes, in which agrin-induced AChR clusters form normally but rapidly disintegrate after agrin withdrawal, pervanadate addition stabilized AChR clusters. The PTP SHP-2, known to be enriched at the NMJ, associated and colocalized with MuSK, and agrin increased this interaction. Specific SHP-2 knockdown by RNA interference reduced the stability of AChR clusters in wild-type myotubes. Similarly, knockdown of SHP-2 in adult mouse soleus muscle by electroporation of RNA interference constructs caused disassembly of pretzel-shaped AChR-rich areas in vivo. Finally, we found that src-/-;fyn-/- myotubes contained elevated levels of SHP-2 protein. CONCLUSION Our data are the first to show that the fine balance between PTPs and SFKs is a key aspect in stabilization of postsynaptic AChR clusters. One phosphatase that acts in this equilibrium is SHP-2. Thus, PTPs such as SHP-2 stabilize AChR clusters under normal circumstances, but when these PTPs are not balanced by SFKs, they render clusters unstable.
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Kwon M, Ling Y, Maile LA, Badley-Clark J, Clemmons DR. Recruitment of the tyrosine phosphatase Src homology 2 domain tyrosine phosphatase-2 to the p85 subunit of phosphatidylinositol-3 (PI-3) kinase is required for insulin-like growth factor-I-dependent PI-3 kinase activation in smooth muscle cells. Endocrinology 2006; 147:1458-65. [PMID: 16306077 DOI: 10.1210/en.2005-1115] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IGF-I stimulates smooth muscle cell (SMC) migration and the phosphatidylinositol-3 (PI-3) kinase pathway plays an important role in mediating the IGF-I-induced migratory response. Prior studies have shown that the tyrosine phosphatase Src homology 2 domain tyrosine phosphatase (SHP)-2 is necessary to activate PI-3 kinase in response to growth factors and expression of a phosphatase inactive form of SHP-2 (SHP-2/C459S) impairs IGF-I-stimulated cell migration. However, the mechanism by which SHP-2 phosphatase activity or the recruitment of SHP-2 to other signaling molecules contributes to IGF-I stimulated PI-3 kinase activation has not been determined. SMCs that had stable expression of SHP-2/C459S had reduced cell migration and Akt activation in response to IGF-I, compared with SMC-expressing native SHP-2. Similarly in cells expressing native SHP-2, IGF-I induced SHP-2 binding to p85, whereas in cells expressing SHP-2/C459S, there was no increase. Because the C459S substitution results in loss of the ability of SHP-2 to disassociate from its substrates, making it inaccessible not only to p85 but also the other proteins, a p85 mutant in which tyrosines 528 and 556 were changed to phenylalanines was prepared to determine whether this would disrupt the p85/SHP-2 interaction and whether the loss of this specific interaction would alter IGF-I stimulated the cell migration. Substitution for these tyrosines in p85 resulted in loss of SHP-2 recruitment and was associated with a reduction in association of the p85/p110 complex with insulin receptor substrate-1. Cells stably expressing this p85 mutant also showed a decrease in IGF-I-stimulated PI-3 kinase activity and cell migration. Preincubation of cells with a cell-permeable peptide that contains the tyrosine556 motif of p85 also disrupted SHP-2 binding to p85 and inhibited the IGF-I-induced increase in cell migration. The findings indicate that tyrosines 528 and 556 in p85 are required for SHP-2 association. SHP-2 recruitment to p85 is required for IGF-I-stimulated association of the p85/p110 complex with insulin receptor substrate-1 and for the subsequent activation of the PI-3 kinase pathway leading to increased cell migration.
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Affiliation(s)
- Mijin Kwon
- Division of Endocrinology, 6111 Thurston-Bowles, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7170, USA
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Abstract
The `signal regulatory protein' SIRPα is an Ig superfamily, transmembrane glycoprotein with a pair of cytoplasmic domains that can bind the phosphatase SHP-2 when phosphorylated on tyrosine. SIRPα is prominent in growth cones of rat cortical neurons and located, together with the tetraspanin CD81, in the growth cone periphery. SIRPα is dynamically associated with Triton-X-100-sensitive, but Brij-98-resistant, lipid microdomains, which also contain CD81. Challenge of growth cones with the integrin-binding extracellular-matrix (ECM) protein, laminin, or with the growth factors, IGF-1 or BDNF, increases SIRPα phosphorylation and SHP-2 binding rapidly and transiently, via Src family kinase activation; phosphorylated SIRPα dissociates from the lipid microdomains. A cytoplasmic tail fragment of SIRPα (cSIRPα), when expressed in primary cortical neurons, also is phosphorylated and binds SHP-2. Expression of wild-type cSIRPα, but not of a phosphorylation-deficient mutant, substantially decreases IGF-1-stimulated axonal growth on laminin. On poly-D-lysine and in control conditions, axonal growth is slower than on laminin, but there is no further reduction in growth rate induced by the expression of cSIRPα. Thus, the effect of cSIRPα on axon growth is dependent upon integrin activation by laminin. These results suggest that SIRPα functions in the modulation of axonal growth by ECM molecules, such as laminin.
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Affiliation(s)
- Xiaoxin X Wang
- Department of Cell and Developmental Biology, University of Colorado School of Medicine and University of Colorado Cancer Center, Aurora, CO 80010, USA
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37
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Goel HL, Breen M, Zhang J, Das I, Aznavoorian-Cheshire S, Greenberg NM, Elgavish A, Languino LR. beta1A integrin expression is required for type 1 insulin-like growth factor receptor mitogenic and transforming activities and localization to focal contacts. Cancer Res 2005; 65:6692-700. [PMID: 16061650 DOI: 10.1158/0008-5472.can-04-4315] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The cells' ability to proliferate in response to growth factor stimulation is significantly altered during cancer progression. To investigate the mechanisms underlying these alterations in prostate cancer, the role and expression of beta1A integrin and type 1 insulin-like growth factor receptor (IGF-IR), known to contribute to cell proliferation and transformation, were analyzed. Using small interfering RNA oligonucleotides to down-regulate beta1A, we show that beta1A expression is required for IGF-IR-mediated prostate cancer cell proliferation and anchorage-independent growth. In vivo, using age-matched transgenic adenocarcinoma of mouse prostate (TRAMP) mice at different stages of prostate cancer [prostatic intraepithelial neoplasia, PIN; well-differentiated adenocarcinoma, WD; and poorly differentiated adenocarcinoma, PD], the expression of beta1A and of IGF-IR was studied. beta1A and IGF-IR expression levels were concurrently up-regulated in high PIN and WD, whereas their expression did not correlate in late-stage PD. In contrast to the up-regulated expression of beta1A, the levels of beta1C, a beta1 cytoplasmic variant that inhibits cell proliferation, were down-regulated in all stages of prostate cancer. A similar expression pattern was observed for a beta1C downstream effector, Grb2-associated binder-1 (Gab1) which is known to inhibit IGF-IR phosphorylation. To analyze in vitro the mechanistic implications of beta1A, beta1C, and Gab1 deregulation in prostate cancer, we investigated whether expression of either beta1 variant in beta1-null cells affected IGF-IR localization. We found that IGF-IR and beta1A were colocalized in highly specialized integrin signaling compartments, designated focal contacts. However, in the presence of beta1C, IGF-IR remained diffuse on the cell surface and did not localize to focal contacts. The findings that beta1 integrins and IGF-IR are concurrently deregulated and that expression of beta1 integrins is necessary to achieve appropriate IGF-IR intracellular distribution point to the important role that the cross-talk between these receptors may have during prostate cancer progression and will be helpful in formulating new therapeutic strategies.
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Affiliation(s)
- Hira Lal Goel
- Department of Cancer Biology and the Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Maile LA, Busby WH, Sitko K, Capps BE, Sergent T, Badley-Clarke J, Clemmons DR. Insulin-like growth factor-I signaling in smooth muscle cells is regulated by ligand binding to the 177CYDMKTTC184 sequence of the beta3-subunit of alphaVbeta3. Mol Endocrinol 2005; 20:405-13. [PMID: 16195248 DOI: 10.1210/me.2005-0241] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The response of smooth muscle cells to IGF-I requires ligand occupancy of the alphaVbeta3 integrin. We have shown that vitronectin (Vn) is required for IGF-I-stimulated migration or proliferation, whereas the anti-alphaVbeta3 monoclonal antibody, LM609, which inhibits ligand binding, blocks responsiveness of these cells to IGF-I. The amino acids 177-184 ((177)CYDMKTTC(184)) within the extracellular domain of beta3 have been proposed to confer the ligand specificity of alphaVbeta3; therefore, we hypothesized that ligand binding to the 177-184 cysteine loop of beta3 may be an important regulator of the cross talk between alphaVbeta3 and IGF-I in SMCs. Here we demonstrate that blocking ligand binding to a specific amino acid sequence within the beta3 subunit of alphaVbeta3 (i.e. amino acids 177-184) blocked Vn binding to the beta3 subunit of alphaVbeta3 and correspondingly beta3 phosphorylation was decreased. In the presence of this antibody, IGF-I-stimulated Shc phosphorylation and ERK 1/2 activation were impaired, and this was associated with an inhibition in the ability of IGF-I to stimulate an increase in migration or proliferation. Furthermore, in cells expressing a mutated form of beta3 in which three critical residues within the 177-184 sequence were altered beta3 phosphorylation was decreased. This was associated with a loss of IGF-I-stimulated Shc phosphorylation and impaired smooth muscle cell proliferation in response to IGF-I. In conclusion, we have demonstrated that the 177-184 sequence of beta3 is necessary for Vn binding to alphaVbeta3 and that ligand occupancy of this site is necessary for an optimal response of smooth muscle cells to IGF-I.
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Affiliation(s)
- Laura A Maile
- Division of Endocrinology, University of North Carolina, Chapel Hill, North Carolina 27599-7170, USA.
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Kapur S, Mohan S, Baylink DJ, Lau KHW. Fluid shear stress synergizes with insulin-like growth factor-I (IGF-I) on osteoblast proliferation through integrin-dependent activation of IGF-I mitogenic signaling pathway. J Biol Chem 2005; 280:20163-70. [PMID: 15778506 DOI: 10.1074/jbc.m501460200] [Citation(s) in RCA: 50] [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
This study tested the hypothesis that shear stress interacts with the insulin-like growth factor-I (IGF-I) pathway to stimulate osteoblast proliferation. Human TE85 osteosarcoma cells were subjected to a steady shear stress of 20 dynes/cm(2) for 30 min followed by 24-h incubation with IGF-I (0-50 ng/ml). IGF-I increased proliferation dose-dependently (1.5-2.5-fold). Shear stress alone increased proliferation by 70%. The combination of shear stress and IGF-I stimulated proliferation (3.5- to 5.5-fold) much greater than the additive effects of each treatment alone, indicating a synergistic interaction. IGF-I dose-dependently increased the phosphorylation level of Erk1/2 by 1.2-5.3-fold and that of IGF-I receptor (IGF-IR) by 2-4-fold. Shear stress alone increased Erk1/2 and IGF-IR phosphorylation by 2-fold each. The combination treatment also resulted in synergistic enhancements in both Erk1/2 and IGF-IR phosphorylation (up to 12- and 8-fold, respectively). Shear stress altered IGF-IR binding only slightly, suggesting that the synergy occurred primarily at the post-ligand binding level. Recent studies have implicated a role for integrin in the regulation of IGF-IR phosphorylation and IGF-I signaling. To test whether the synergy involves integrin-dependent mechanisms, the effect of echistatin (a disintegrin) on proliferation in response to shear stress +/- IGF-I was measured. Echistatin reduced basal proliferation by approximately 60% and the shear stress-induced mitogenic response by approximately 20%. It completely abolished the mitogenic effect of IGF-I and that of the combination treatment. Shear stress also significantly reduced the amounts of co-immunoprecipitated SHP-2 and -1 with IGF-IR, suggesting that the synergy between shear stress and IGF-I in osteoblast proliferation involves integrin-dependent recruitment of SHP-2 and -1 away from IGF-IR.
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Affiliation(s)
- Sonia Kapur
- Musculoskeletal Disease Center, Jerry L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda, California 92357, USA
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