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RNA-Binding Protein Musashi1 Is a Central Regulator of Adhesion Pathways in Glioblastoma. Mol Cell Biol 2015; 35:2965-78. [PMID: 26100017 DOI: 10.1128/mcb.00410-15] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/10/2015] [Indexed: 12/14/2022] Open
Abstract
The conserved RNA-binding protein Musashi1 (MSI1) has emerged as a key oncogenic factor in numerous solid tumors, including glioblastoma. However, its mechanism of action has not yet been established comprehensively. To identify its target genes comprehensively and determine the main routes by which it influences glioblastoma phenotypes, we conducted individual-nucleotide resolution cross-linking and immunoprecipitation (iCLIP) experiments. We confirmed that MSI1 has a preference for UAG sequences contained in a particular structural context, especially in 3' untranslated regions. Although numerous binding sites were also identified in intronic sequences, our RNA transcriptome sequencing analysis does not favor the idea that MSI1 is a major regulator of splicing in glioblastoma cells. MSI1 target mRNAs encode proteins that function in multiple pathways of cell proliferation and cell adhesion. Since these associations indicate potentially new roles for MSI1, we investigated its impact on glioblastoma cell adhesion, morphology, migration, and invasion. These processes are known to underpin the spread and relapse of glioblastoma, in contrast to other tumors where metastasis is the main driver of recurrence and progression.
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Williams AS, Kang L, Zheng J, Grueter C, Bracy DP, James FD, Pozzi A, Wasserman DH. Integrin α1-null mice exhibit improved fatty liver when fed a high fat diet despite severe hepatic insulin resistance. J Biol Chem 2015; 290:6546-57. [PMID: 25593319 DOI: 10.1074/jbc.m114.615716] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Hepatic insulin resistance is associated with increased collagen. Integrin α1β1 is a collagen-binding receptor expressed on hepatocytes. Here, we show that expression of the α1 subunit is increased in hepatocytes isolated from high fat (HF)-fed mice. To determine whether the integrin α1 subunit protects against impairments in hepatic glucose metabolism, we analyzed glucose tolerance and insulin sensitivity in HF-fed integrin α1-null (itga1(-/-)) and wild-type (itga1(+/+)) littermates. Using the insulin clamp, we found that insulin-stimulated hepatic glucose production was suppressed by ∼50% in HF-fed itga1(+/+) mice. In contrast, it was not suppressed in HF-fed itga1(-/-) mice, indicating severe hepatic insulin resistance. This was associated with decreased hepatic insulin signaling in HF-fed itga1(-/-) mice. Interestingly, hepatic triglyceride and diglyceride contents were normalized to chow-fed levels in HF-fed itga1(-/-) mice. This indicates that hepatic steatosis is dissociated from insulin resistance in HF-fed itga1(-/-) mice. The decrease in hepatic lipid accumulation in HF-fed itga1(-/-) mice was associated with altered free fatty acid metabolism. These studies establish a role for integrin signaling in facilitating hepatic insulin action while promoting lipid accumulation in mice challenged with a HF diet.
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Affiliation(s)
| | - Li Kang
- From the Departments of Molecular Physiology and Biophysics and
| | - Jenny Zheng
- From the Departments of Molecular Physiology and Biophysics and
| | | | - Deanna P Bracy
- From the Departments of Molecular Physiology and Biophysics and
| | - Freyja D James
- From the Departments of Molecular Physiology and Biophysics and
| | - Ambra Pozzi
- From the Departments of Molecular Physiology and Biophysics and Division of Nephrology, Department of Medicine, and the Department of Medicine, Department of Veteran Affairs, Nashville, Tennessee 37212-2637
| | - David H Wasserman
- From the Departments of Molecular Physiology and Biophysics and Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee 37232 and
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Lai C, Liu X, Tian C, Wu F. Integrin α1 has a long helix, extending from the transmembrane region to the cytoplasmic tail in detergent micelles. PLoS One 2013; 8:e62954. [PMID: 23646163 PMCID: PMC3639902 DOI: 10.1371/journal.pone.0062954] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/26/2013] [Indexed: 12/12/2022] Open
Abstract
Integrin proteins are very important adhesion receptors that mediate cell-cell and cell-extracellular matrix interactions. They play essential roles in cell signaling and the regulation of cellular shape, motility, and the cell cycle. Here, the transmembrane and cytoplasmic (TMC) domains of integrin α1 and β1 were over-expressed and purified in detergent micelles. The structure and backbone relaxations of α1-TMC in LDAO micelles were determined and analyzed using solution NMR. A long helix, extending from the transmembrane region to the cytoplasmic tail, was observed in α1-TMC. Structural comparisons of α1-TMC with reported αIIb-TMC domains indicated different conformations in the transmembrane regions and cytoplasmic tails. An NMR titration experiment indicated weak interactions between α1-TMC and β1-TMC through several α1-TMC residues located at its N-terminal juxta-transmembrane region and C-terminal extended helix region.
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Affiliation(s)
- Chaohua Lai
- Hefei National Laboratory for Physical Science at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Xiaoxi Liu
- Hefei National Laboratory for Physical Science at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Changlin Tian
- Hefei National Laboratory for Physical Science at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, China
- * E-mail: (CT); (FW)
| | - Fangming Wu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, China
- * E-mail: (CT); (FW)
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Yang S, Tian YS, Lee YJ, Yu FH, Kim HM. Mechanisms by which the inhibition of specific intracellular signaling pathways increase osteoblast proliferation on apatite surfaces. Biomaterials 2011; 32:2851-61. [PMID: 21288570 DOI: 10.1016/j.biomaterials.2011.01.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 01/06/2011] [Indexed: 12/30/2022]
Abstract
Osteoblasts proliferate slowly on the surface of calcium phosphate apatite which is widely used as a substrate biomaterial in bone regeneration. Owing to poor adhesion signaling in the cells grown on the calcium phosphate surface, inadequate growth factor signaling is generated to trigger cell cycle progression. The present study investigated an intracellular signal transduction pathway involved in the slow cell proliferation in osteoblasts grown on the calcium phosphate surface. Small GTPase RhoA and phosphatase and tensin homolog (PTEN) were more activated in cells grown on the surface of calcium phosphate apatite than on tissue culture plate. Specific inhibition of RhoA and PTEN induced the cells on calcium phosphate apatite surface to proliferate at a similar rate as cells on tissue culture plate surface. Specific inhibition of ROCK, which is a downstream effector of RhoA and an upstream activator of PTEN also increased proliferation of these osteoblasts. Present results indicate that physical property of calcium phosphate crystals that impede cell proliferation may be surmounted by the inhibition of the RhoA/ROCK/PTEN pathway to rescue delayed proliferation of osteoblasts on the calcium phosphate apatite surface. In addition, specific inhibition of ROCK promoted cell migration and osteoblast differentiation. Inhibition of the RhoA/ROCK/PTEN intracellular signaling pathway is expected to enhance cell activity to promote and accelerate bone regeneration on the calcium phosphate apatite surface.
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Affiliation(s)
- Seungwon Yang
- Laboratory for the Study of Molecular Biointerfaces, Department of Oral Histology and Developmental Biology, Program of Cell and Developmental Biology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea
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Yotsumoto N, Takeoka M, Yokoyama M. Tail-suspended mice lacking calponin H1 experience decreased bone loss. TOHOKU J EXP MED 2010; 221:221-7. [PMID: 20551601 DOI: 10.1620/tjem.221.221] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Calponin h1 (CNh1) is an actin-binding protein originally isolated from vascular smooth muscle and has been reported to suppress bone formation. We are therefore curious how CNh1 is involved in bone loss that is caused by space flight in microgravity. We assessed the effects of tail suspension (TS) in C57BL/6J wild (CN+/+) and CNh1-deleted (CN-/-) mice to elucidate the role of CNh1 in bone loss under weightless conditions. Bone mineral density (BMD) of tibiae was measured by single energy X-ray absorptiometry, and bone volume fraction (BV/TV), mineral apposition rate (MAR), and bone formation rate (BFR/BS) were measured by bone histomorphometry. BMD, BV/TV, MAR, and BFR/BS were lower in CN+/+ mice with TS than in those without. In the CN-/- group, however, the decrease in each of these parameters by TS was ameliorated. Decreases in serum osteocalcin levels by TS in CN+/+ mice were attenuated in CN-/- mice. Furthermore, urinary deoxypyridinolin (DPD), an indicator of bone resorption, was increased in CN+/+ mice following TS, but not in CN-/- mice. In transfection experiments, the degree of induction of bone formation markers, alkaline phosphatase (ALP) activity and bone morphogenetic protein (BMP)-4 mRNA expression, under stimulation with BMP-2, was lower in MC3T3-E1 mouse osteoblast-like cells expressing CNh1 than that in mock transfected cells. Notably, the BMP-2-induced ALP activity was decreased by CNh1 expression, which was partially rescued by treatment with the Rho kinase inhibitor Y27632. Taken together, these results indicate that CNh1 is responsible for weightlessness-induced bone loss in part through Rho signaling pathway.
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Functional analysis of the cytoplasmic domain of the integrin {alpha}1 subunit in endothelial cells. Blood 2008; 112:3242-54. [PMID: 18647959 DOI: 10.1182/blood-2007-12-126433] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Integrin alpha1beta1, the major collagen type IV receptor, is expressed by endothelial cells and plays a role in both physiologic and pathologic angiogenesis. Because the molecular mechanisms whereby this collagen IV receptor mediates endothelial cell functions are poorly understood, truncation and point mutants of the integrin alpha1 subunit cytoplasmic tail (amino acids 1137-1151) were generated and expressed into alpha1-null endothelial cells. We show that alpha1-null endothelial cells expressing the alpha1 subunit, which lacks the entire cytoplasmic tail (mutant alpha1-1136) or expresses all the amino acids up to the highly conserved GFFKR motif (mutant alpha1-1143), have a similar phenotype to parental alpha1-null cells. Pro(1144) and Leu(1145) were shown to be necessary for alpha1beta1-mediated endothelial cell proliferation; Lys(1146) for adhesion, migration, and tubulogenesis and Lys(1147) for tubulogenesis. Integrin alpha1beta1-dependent endothelial cell proliferation is primarily mediated by ERK activation, whereas migration and tubulogenesis require both p38 MAPK and PI3K/Akt activation. Thus, distinct amino acids distal to the GFFKR motif of the alpha1 integrin cytoplasmic tail mediate activation of selective downstream signaling pathways and specific endothelial cell functions.
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Cerna J, Cerecedo D, Ortega A, García-Sierra F, Centeno F, Garrido E, Mornet D, Cisneros B. Dystrophin Dp71f associates with the beta1-integrin adhesion complex to modulate PC12 cell adhesion. J Mol Biol 2006; 362:954-65. [PMID: 16935300 PMCID: PMC1952692 DOI: 10.1016/j.jmb.2006.07.075] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2006] [Revised: 07/25/2006] [Accepted: 07/26/2006] [Indexed: 02/04/2023]
Abstract
Dystrophin Dp71 is the main product of the Duchenne muscular dystrophy gene in the brain; however, its function is unknown. To study the role of Dp71 in neuronal cells, we previously generated by antisense treatment PC12 neuronal cell clones with decreased Dp71 expression (antisense-Dp71 cells). PC12 cells express two different splicing isoforms of Dp71, a cytoplasmic variant called Dp71f and a nuclear isoform called Dp71d. We previously reported that antisense-Dp71 cells display deficient adhesion to substrate and reduced immunostaining of beta1-integrin in the cell area contacting the substrate. In this study, we isolated additional antisense-Dp71 clones to analyze in detail the potential involvement of Dp71f isoform with the beta1-integrin adhesion system of PC12 cells. Immunofluorescence analyses as well as immunoprecipitation assays demonstrated that the PC12 cell beta1-integrin adhesion complex is composed of beta1-integrin, talin, paxillin, alpha-actinin, FAK and actin. In addition, our results showed that Dp71f associates with most of the beta1-integrin complex components (beta1-integrin, FAK, alpha-actinin, talin and actin). In the antisense-Dp71 cells, the deficiency of Dp71 provokes a significant reduction of the beta1-integrin adhesion complex and, consequently, the deficient adhesion of these cells to laminin. In vitro binding experiments confirmed the interaction of Dp71f with FAK and beta1-integrin. Our data indicate that Dp71f is a structural component of the beta1-integrin adhesion complex of PC12 cells that modulates PC12 cell adhesion by conferring proper complex assembly and/or maintenance.
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Affiliation(s)
- Joel Cerna
- Departmento de Génética y Biologia Molecular
Centro de Investigacion y de Estufios Avanzados del I.P.N.Av. Instituto Politécnico Nacional 2508, Col. San PedroZacatenco, México, D. F. 07360,MX
| | - Doris Cerecedo
- Laboratorio de Hematologia
Escuela Superior de medecina y Homeopatia I.P.N.Wilfrido Massieu Helguera 239 Frac. La Escalera Ticomán. México, D. F. 07320,MX
| | - Arturo Ortega
- Departmento de Génética y Biologia Molecular
Centro de Investigacion y de Estufios Avanzados del I.P.N.Av. Instituto Politécnico Nacional 2508, Col. San PedroZacatenco, México, D. F. 07360,MX
| | - Francisco García-Sierra
- Deparmento de Biologia Cellular
Centro de Investigacion y de Estudios Avanzados del I.P.N.Av. Instituto Politécnico Nacional 2508 Col. San Pedro Zacatenco, México, D. F. 07360,MX
| | - Federico Centeno
- Departmento de Génética y Biologia Molecular
Centro de Investigacion y de Estufios Avanzados del I.P.N.Av. Instituto Politécnico Nacional 2508, Col. San PedroZacatenco, México, D. F. 07360,MX
| | - Efrain Garrido
- Departmento de Génética y Biologia Molecular
Centro de Investigacion y de Estufios Avanzados del I.P.N.Av. Instituto Politécnico Nacional 2508, Col. San PedroZacatenco, México, D. F. 07360,MX
| | - Dominique Mornet
- Muscles et pathologies chroniques
Université Montpellier I EA701Institut de Biologie, Boulevard Henry IV, 34062 Montpellier,FR
| | - Bulmaro Cisneros
- Departmento de Génética y Biologia Molecular
Centro de Investigacion y de Estufios Avanzados del I.P.N.Av. Instituto Politécnico Nacional 2508, Col. San PedroZacatenco, México, D. F. 07360,MX
- * Correspondence should be adressed to: Cisneros Bulmaro
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Enríquez-Aragón JA, Cerna-Cortés J, Bermúdez de León M, García-Sierra F, González E, Mornet D, Cisneros B. Dystrophin Dp71 in PC12 cell adhesion. Neuroreport 2005; 16:235-8. [PMID: 15706226 PMCID: PMC2494584 DOI: 10.1097/00001756-200502280-00006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Previously, we reported that PC12 cells with decreased Dp71 expression (antisense-Dp71 cells) display deficient nerve-growth-factor-induced neurite outgrowth. In this study, we show that disturbed neurite outgrowth of antisense-Dp71 cells is accompanied by decreased adhesion activity on laminin, collagen and fibronectin. In wild-type cells, the immunostaining of Dp71 and beta1-integrin overlaps in the basal area contacting the substrate, but staining of both proteins decrease in the antisense-Dp71 cells. Morphology of antisense-Dp71 cells at the electron microscopic level is characterized by the lack of filopodia, cellular projections involved in adhesion. Our findings suggest that Dp71 is required for the efficient PC12 cell attachment to beta1-integrin-dependent substrata and that decreased adhesion activity of the antisense-Dp71 cells could determine their deficiency to extend neurites.
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Affiliation(s)
| | - Joel Cerna-Cortés
- Department of Genetics and Molecular Biology
Centro de Investigation y de Estudios Avanzados del IPNMX
| | - Mario Bermúdez de León
- Department of Genetics and Molecular Biology
Centro de Investigation y de Estudios Avanzados del IPNMX
| | | | - Everardo González
- Department of Genetics and Molecular Biology
Centro de Investigation y de Estudios Avanzados del IPNMX
| | - Dominique Mornet
- Muscle et pathologies
INSERM : ERI25IFR3Université Montpellier I : EA4202hopital arnaud de villeneuve
371, avenue du doyen gaston giraud 34295 Montpellier Cedex 05,FR
- * Correspondence should be adressed to: Dominique Mornet
| | - Bulmaro Cisneros
- Department of Genetics and Molecular Biology
Centro de Investigation y de Estudios Avanzados del IPNMX
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Ben-Horin S, Bank I. The role of very late antigen-1 in immune-mediated inflammation. Clin Immunol 2004; 113:119-29. [PMID: 15451466 DOI: 10.1016/j.clim.2004.06.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Accepted: 06/21/2004] [Indexed: 12/26/2022]
Abstract
The alpha1beta1 integrin, also known as "very late antigen" (VLA)-1, is normally expressed on mesenchymal cells, some epithelial cells, activated T cells, and macrophages, and interacts, via the I-domain of the extracellular domain of the alpha1 subunit, with collagen molecules in the extracellular matrix (ECM). By "outside-in" transmembranal signaling to the interior of the cell, it mediates adhesion, migration, proliferation, remodeling of the ECM, and cytokine secretion by endothelial cells, mesangial cells, fibroblasts, and immunocytes. Importantly, its expressions and functions are enhanced by inflammatory cytokines including interferon (IFN)gamma and tumor necrosis factor (TNF)alpha, thus augmenting angiogenesis and fibrosis linked, in particular, to inflammation. Moreover, within the immune system, VLA-1 marks effector memory CD4+ and CD8+ T cells that are retained in extralymphatic tissues by interactions of the integrin with collagen and produce high levels of IFNgamma. Thus, immune-mediated inflammation in vivo is inhibited by blockade of the VLA-1-collagen interaction in experimental animal models of arthritis, colitis, nephritis, and graft versus host disease (GVHD), suggesting that inhibiting the interaction of the alpha1 I-domain with its ligands or modulating "outside-in" signaling by VLA-1 would be a useful approach in the human diseases simulated by these experimental models.
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Affiliation(s)
- Shomron Ben-Horin
- Laboratory for Immunoregulation, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
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Bank I, Achiron A, Levie G, Koltakov A, Mandel M. Interaction of disease-related antigen-reactive T-cell lines from multiple sclerosis patients with type IV collagen: role of integrin VLA-1 and effects of irradiation. J Clin Immunol 2002; 22:153-63. [PMID: 12078857 DOI: 10.1023/a:1015472013500] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Multiple sclerosis (MS), a chronic demyelinating disease, is thought to be initiated by pathogenic T cells that transmigrate the vascular endothelium and enter the brain through vascular and parenchymal basement membranes (BM). Vaccination with T-cell lines reactive with myelin basic protein (MBP) and myelin oligodendrocytic glycoprotein (MOG) epitopes, expanded with interleukin-2 (IL-2), and attenuated by ionizing radiation is currently being evaluated as a therapeutic modality for this disease. We examined mechanisms potentially involved in pathogenic cell migration into the central nervous system (CNS) and the influence of irradiation on these processes. Seven of 7 autoantigen-responsive T-cell lines from MS patients adhered to collagen IV, the major collagenous constituent of BMs. This adhesion was inhibited almost completely by monoclonal antibody (MAb) to very late antigen (VLA)-1 and partially by anti-VLA-2. T-cell lines from healthy donors adhered more variably to collagen IV. Furthermore, patient derived T cells actively transmigrated through a collagen IV gel toward medium containing TNF-a, in a process that was inhibited by MAbs to VLA-1. Ionizing radiation at the dose used in vaccine preparation, inhibited morphological polarization associated with migratory capability, induced integrin clustering on the cell membrane, and abrogated adhesion to collagen IV. These findings may have important implications for understanding the pathogenesis of MS and how irradiation of potentially pathogenic T cells produces a reagent with possible therapeutic effects in T-cell vaccination (TCV).
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Affiliation(s)
- Ilan Bank
- Department of Medicine F, Sheba Medical Center and Tel Aviv University, Tel Hashomer, Israel.
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