scholarly journals Dynamic changes in the osteoclast cytoskeleton in response to growth factors and cell attachment are controlled by β3 integrin

2003 ◽  
Vol 162 (3) ◽  
pp. 499-509 ◽  
Author(s):  
Roberta Faccio ◽  
Deborah V. Novack ◽  
Alberta Zallone ◽  
F. Patrick Ross ◽  
Steven L. Teitelbaum
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cell Attachment ◽  
Cytoplasmic Tail ◽  
Cytoplasmic Domain ◽  
Small Gtpases ◽  
Cytoskeletal Reorganization ◽  
Integrin Activation ◽  
Intracellular Signals ◽  
Β3 Integrin

The β3 integrin cytoplasmic domain, and specifically S752, is critical for integrin localization and osteoclast (OC) function. Because growth factors such as macrophage colony–stimulating factor and hepatocyte growth factor affect integrin activation and function via inside-out signaling, a process requiring the β integrin cytoplasmic tail, we examined the effect of these growth factors on OC precursors. To this end, we retrovirally expressed various β3 integrins with cytoplasmic tail mutations in β3-deficient OC precursors. We find that S752 in the β3 cytoplasmic tail is required for growth factor–induced integrin activation, cytoskeletal reorganization, and membrane protrusion, thereby affecting OC adhesion, migration, and bone resorption. The small GTPases Rho and Rac mediate cytoskeletal reorganization, and activation of each is defective in OC precursors lacking a functional β3 subunit. Activation of the upstream mediators c-Src and c-Cbl is also dependent on β3. Interestingly, although the FAK-related kinase Pyk2 interacts with c-Src and c-Cbl, its activation is not disrupted in the absence of functional β3. Instead, its activation is dependent upon intracellular calcium, and on the β2 integrin. Thus, the β3 cytoplasmic domain is responsible for activation of specific intracellular signals leading to cytoskeletal reorganization critical for OC function.

Abstract 496: Competition Between Filamin and Kindlin-2 Regulates Integrin Activation

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Mitali Das ◽  
Sujay Ithychanda ◽  
Kamila Bledzka ◽  
Jun Qin ◽  
Edward F Plow
Keyword(s):  
Cell Migration ◽  
K562 Cells ◽  
Cell Types ◽  
Suppressive Effect ◽  
Integrin Activation ◽  
Intracellular Signals ◽  
Integrin Binding Site ◽  
Multiple Cell ◽  
Β3 Integrin ◽  
Inside Out

Cell migration and adhesion during hemostasis, angiogenesis and inflammation are dynamically regulated by integrin heterodimeric adhesion receptors. Their interactions with cytosolic proteins, filamin (FLN), talin (TLN) and Kindlin (Kn2) enable them to convey intracellular signals (inside-out-signaling) to the external environment by engaging extracellular matrix ligands. While TLN and Kn2 activate integrins, FLN inhibits cell migration. TLN and Kn2 bind to membrane-proximal and -distal NPxY motifs of β integrin cytoplasmic tails (CTs), respectively, and an integrin binding site for FLN resides in between these two sequences. Competition between TLN and FLN regulates integrin activation, but it is unknown if FLN and Kn2 compete and regulate integrin inside-out signaling. This competition was tested using αIIbβ3 (platelet-specific) and β7 (lymphocyte-specific; strong FLN binder) integrins in multiple cell types. siRNA depletion of FLNA in K562 cells stably expressing αIIbβ3 integrin (K562-αIIbβ3) significantly enhanced PAC-1 (specific for activated αIIbβ3) binding compared to control siRNA, demonstrating its effect on β3 activation. In pulldown assays using GST-β3 CT, Kn2 bound β3 in CHO lysates transfected with Kn2, either alone or with FLN repeat 21; however, FLN binding to β3 CT was observed only when FLN repeat 21 was expressed alone. Under similar conditions using GST-β7 CT, FLN-β7 interaction was not perturbed by Kn2. This was more pronounced in endothelial cell lysates where GST-β7 CT bound endogenous FLNA but not Kn2. Weak talin-β7 CT binding in this assay was noted. Moreover, in K562-αIIbβ3 cells, exogenous Kn2 overcame the suppressive effect of FLN on αIIbβ3 activation. Overall, our data shows that FLN inhibits β3 integrin function, and competition between FLN and Kn2 can indeed regulate integrin activation.

scholarly journals Sustained increase in 1,2-diacylglycerol precedes DNA synthesis in epidermal-growth-factor-stimulated fibroblasts. Evidence for stimulated phosphatidylcholine hydrolysis

1990 ◽  
Vol 267 (2) ◽  
pp. 501-507 ◽  
Author(s):  
T M Wright ◽  
H S Shin ◽  
D M Raben
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Dna Synthesis ◽  
De Novo ◽  
Phospholipid Metabolism ◽  
Intracellular Signals ◽  
Mitogenic Signalling ◽  
Epidermal Growth ◽  
Hydrolysis Of

A property common to many growth factors is that they must be present for several hours before the commitment to DNA synthesis and cell division occurs. The intracellular signals that are relevant during this period are poorly defined. We examined the formation of 1,2-diacylglycerol in IIC9 fibroblasts after stimulation with epidermal growth factor (EGF), and found that the mass of this lipid remained elevated for at least four hours. The concentration-dependence of EGF-stimulated 1,2-diacylglycerol production and [3H]thymidine incorporation were similar. Studies of phospholipid metabolism strongly suggested that phosphatidylcholine was the source of the 1,2-diacylglycerol generated in response to EGF. EGF did not stimulate the hydrolysis of other phospholipids, including the phosphoinositides, nor did it increase synthesis de novo of 1,2-diacylglycerol. This pattern of sustained 1,2-diacylglycerol formation from phosphatidylcholine may be important in the mitogenic signalling of EGF and potentially other growth factors.

scholarly journals Interaction between Insulin-Like Growth Factor-I Receptor and αVβ3 Integrin Linked Signaling Pathways: Cellular Responses to Changes in Multiple Signaling Inputs

2005 ◽  
Vol 19 (1) ◽  
pp. 1-11 ◽  
Author(s):  
D. R. Clemmons ◽  
L. A. Maile
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Cell Attachment ◽  
Transmembrane Protein ◽  
Tyrosine Phosphatase ◽  
Integrin Αvβ3 ◽  
Signaling Molecules ◽  
Αvβ3 Integrin ◽  
Igf I

Abstract Integrins are heterodimeric transmembrane proteins that mediate cell attachment to extracellular matrix, migration, division, and inhibition of apoptosis. Because growth factors are also important for these processes, there has been interest in cooperative signaling between growth factor receptors and integrins. IGF-I is an important growth factor for vascular cells. One integrin, αVβ3, that is expressed in smooth muscle cells modulates IGF-I actions. Ligand occupancy of αVβ3 is required for IGF-I to stimulate cell migration and division. Src homology 2 containing tyrosine phosphatase (SHP-2) is a tyrosine phosphatase whose recruitment to signaling molecules is stimulated by growth factors including IGF-I. If αVβ3 ligand occupancy is inhibited, there is no recruitment of SHP-2 to αVβ3 and its transfer to downstream signaling molecules is blocked. Ligand occupancy of αVβ3 stimulates tyrosine phosphorylation of the β3-subunit, resulting in recruitment of SHP-2. This transfer is mediated by an insulin receptor substrate-1-related protein termed DOK-1. Subsequently, SHP-2 is transferred to another transmembrane protein, SHPS-1. This transfer requires IGF-I receptor-mediated tyrosine phosphorylation of SHPS-1, which contains two YXXL motifs that mediate SHP-2 binding. The transfer of SHP-2 to SHPS-1 is also required for recruitment of Shc to SHPS-1. Ligand occupancy of αVβ3 results in sustained Shc phosphorylation and enhanced Shc recruitment. Shc activation results in induction of MAPK. Inhibition of the Shc/SHPS-1 complex formation results in failure to achieve sustained MAPK activation and an attenuated mitogenic response. Thus, within the vessel wall, a mechanism exists whereby ligand occupancy of the αVβ3 integrin is required for assembly of a multicomponent membrane signaling complex that is necessary for cells to respond optimally to IGF-I.

scholarly journals BIOMARKERS, NEOANGIOGENESIS AND GROWTH FACTORS IN PANCREATIC CANCER

2019 ◽  
Vol 6 (3) ◽  
pp. 51-64
Author(s):  
E. M. Frantsiyants ◽  
O. I. Kit ◽  
V. I. Aleynov ◽  
I. A. Goroshinskaya
Keyword(s):  
Pancreatic Cancer ◽  
Growth Factors ◽  
Growth Factor ◽  
Rapid Progression ◽  
Therapeutic Effects ◽  
Intracellular Signals ◽  
Igf I ◽  
Key Factor ◽  
Endothelial Growth Factor

Pancreatic cancer (PC) is a lethal malignant tumor characterized by a rapid progression, invasiveness and resistance to radiochemotherapy. The development of biomarkers for the early diagnosis of the disease is relevant. Angiogenesis has been identified as a key factor in a number of pathological conditions, including cancer. The proangiogenic signaling molecule – vascular endothelial growth factor (VEGF) and its receptors play a central role in tumor angiogenesis. In this review, we also highlight the dual role of growth factor-β (TGF-β) and touch upon the prospects for therapeutic effects on targets associated with TGF-β signaling in pancreatic cancer. A growing interest is attracted to the role of insulin-like growth factors IGF-I and IGF-II in cancer diseases. IGF-I and its receptor are highly expressed on the surface of pancreatic cancer cell lines that initiate the transduction of intracellular signals associated with the proliferation, invasion and expression of angiogenesis mediators. And so, the study of markers and growth factors may be a new, viable option for the diagnosis and treatment of pancreatic cancer.

scholarly journals Integrin alpha subunit ratios, cytoplasmic domains, and growth factor synergy regulate muscle proliferation and differentiation.

1996 ◽  
Vol 133 (1) ◽  
pp. 169-184 ◽  
Author(s):  
S K Sastry ◽  
M Lakonishok ◽  
D A Thomas ◽  
J Muschler ◽  
A F Horwitz
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Ectopic Expression ◽  
Cytoplasmic Domain ◽  
Alpha Subunit ◽  
Tgf Beta ◽  
Serum Free ◽  
Proliferative Phase ◽  
Alpha Subunits ◽  
Proliferation And Differentiation

The role of integrins in muscle differentiation was addressed by ectopic expression of integrin alpha subunits in primary quail skeletal muscle, a culture system particularly amenable to efficient transfection and expression of exogenous genes. Ectopic expression of either the human alpha5 subunit or the chicken alpha6 subunit produced contrasting phenotypes. The alpha5-transfected myoblasts remain in the proliferative phase and are differentiation inhibited even in confluent cultures. In contrast, myoblasts that overexpress the alpha6 subunit exhibit inhibited proliferation and substantial differentiation. Antisense suppression of endogenous quail alpha6 expression inhibits myoblast differentiation resulting in sustained proliferation. These effects of ectopic alpha subunit expression are mediated, to a large extent, by the cytoplasmic domains. Ectopic expression of chimeric alpha subunits, alpha5ex/6cyto and alpha6ex/5cyto, produced phenotypes opposite to those observed with ectopic alpha5 or alpha6 expression. Myoblasts that express alpha5ex/6cyto show decreased proliferation while differentiation is partially restored. In contrast, the alpha6ex/5cyto transfectants remain in the proliferative phase unless allowed to become confluent for at least 24 h. Furthermore, expression of human alpha5 subunit cytoplasmic domain truncations, before and after the conserved GFFKR motif, shows that this sequence is important in alpha5 regulation of differentiation. Ectopic alpha5 and alpha6 expression also results in contrasting responses to the mitogenic effects of serum growth factors. Myoblasts expressing the human alpha5 subunit differentiate only in the absence of serum while differentiation of untransfected and alpha6-transfected myoblasts is insensitive to serum concentration. Addition of individual, exogenous growth factors to alpha5-transfected myoblasts results in unique responses that differ from their effects on untransfected cells. Both bFGF or TGFbeta inhibit the serum-free differentiation of alpha5-transfected myoblasts, but differ in that bFGF stimulates proliferation whereas TGF-beta inhibits it. Insulin or TGF-alpha promote proliferation and differentiation of alpha5-transfected myoblasts; however, insulin alters myotube morphology. TGF-alpha or PDGF-BB enhance muscle alpha-actinin organization into myofibrils, which is impaired in differentiated alpha5 cultures. With the exception of TGF-alpha, these growth factor effects are not apparent in untransfected myoblasts. Finally, myoblast survival under serum-free conditions is enhanced by ectopic alpha5 expression only in the presence of bFGF and insulin while TGF-alpha and TGF-beta promote survival of untransfected myoblasts. Our observations demonstrate (1) a specificity for integrin alpha subunits in regulating myoblast proliferation and differentiation; (2) that the ratio of integrin expression can affect the decision to proliferate or differentiate; (3) a role for the alpha subunit cytoplasmic domain in mediating proliferative and differentiative signals; and (4) the regulation of proliferation, differentiation, cytoskeletal assembly, and cell survival depend critically on the expression levels of different integrins and the growth factor environment in which the cells reside.

scholarly journals The F1 loop of the talin head domain acts as a gatekeeper in integrin activation and clustering

2020 ◽  
Vol 133 (19) ◽  
pp. jcs239202 ◽  
Author(s):  
Sampo Kukkurainen ◽  
Latifeh Azizi ◽  
Pingfeng Zhang ◽  
Marie-Claude Jacquier ◽  
Mo Baikoghli ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cytoplasmic Tail ◽  
First Person ◽  
Integrin Activation ◽  
Inner Membrane ◽  
Flexible Loop ◽  
Head Domain ◽  
Integrin Clustering ◽  
Membrane Bound ◽  
Β3 Integrin

ABSTRACTIntegrin activation and clustering by talin are early steps of cell adhesion. Membrane-bound talin head domain and kindlin bind to the β integrin cytoplasmic tail, cooperating to activate the heterodimeric integrin, and the talin head domain induces integrin clustering in the presence of Mn2+. Here we show that kindlin-1 can replace Mn2+ to mediate β3 integrin clustering induced by the talin head, but not that induced by the F2–F3 fragment of talin. Integrin clustering mediated by kindlin-1 and the talin head was lost upon deletion of the flexible loop within the talin head F1 subdomain. Further mutagenesis identified hydrophobic and acidic motifs in the F1 loop responsible for β3 integrin clustering. Modeling, computational and cysteine crosslinking studies showed direct and catalytic interactions of the acidic F1 loop motif with the juxtamembrane domains of α- and β3-integrins, in order to activate the β3 integrin heterodimer, further detailing the mechanism by which the talin–kindlin complex activates and clusters integrins. Moreover, the F1 loop interaction with the β3 integrin tail required the newly identified compact FERM fold of the talin head, which positions the F1 loop next to the inner membrane clasp of the talin-bound integrin heterodimer.This article has an associated First Person interview with the first author of the paper.

scholarly journals Fluid Shear Stress and Fibroblast Growth Factor-2 Increase Endothelial Cell-Associated Vitronectin

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Justin G. Mathew ◽  
Sarah Basehore ◽  
Alisa Morss Clyne
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Growth Factors ◽  
Growth Factor ◽  
Laminar Flow ◽  
Fibroblast Growth Factor 2 ◽  
Fibroblast Growth ◽  
Integrin Activation ◽  
System Activity ◽  
Steady Laminar

Vitronectin is a matricellular protein that plays an important role in both coagulation and angiogenesis through its effects on cell adhesion and the plasminogen system. Vitronectin is known to bind to endothelial cells upon integrin activation. However, the effect of integrin activation by shear stress and growth factors on cell-associated vitronectin and plasminogen system activity has not yet been studied. We therefore exposed human umbilical vein endothelial cells to steady laminar flow, oscillating disturbed flow, or fibroblast growth factor-2 (FGF-2) for 24 hours. We then measured cell-associated vitronectin by Western blot and plasminogen system activity using a Chromozym assay. Steady laminar flow, oscillating disturbed flow, and FGF-2 all increased cell-associated vitronectin, although the vitronectin molecular weight varied among the different conditions. FGF-2 also increased cell-associated vitronectin in microvascular endothelial cells and vascular smooth muscle cells. The increase in cell-associated vitronectin increased plasminogen system activity. Confocal microscopy showed that vitronectin was primarily located in the basal and intracellular regions.αvβ5integrin inhibition via genistein, an anti-αvβ5antibody, orβ5siRNA knockdown abrogated the FGF-2-induced increase in cell-associated vitronectin and increased plasminogen system activity. These data show that shear stress and growth factors increase cell-associated vitronectin through integrin activation, which may affect coagulation and angiogenesis.

Distinct Domains of αIIbβ3 Support Different Aspects of Outside-In Signal Transduction and Platelet Activation Induced by LSARLAF, an αIIbβ3 Interacting Peptide

2001 ◽  
Vol 86 (09) ◽  
pp. 894-901 ◽  
Author(s):  
Jerry Derrick ◽  
Sanford Shattil ◽  
Mortimer Poncz ◽  
Ralph Gruppo ◽  
Kent Gartner
Keyword(s):  
Signal Transduction ◽  
Platelet Aggregation ◽  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Cytoplasmic Tail ◽  
Cytoplasmic Domain ◽  
Cytoskeletal Reorganization ◽  
Integrin Β3 ◽  
Platelet Spreading

SummaryThe peptide LSARLAF causes αIIbβ3-dependent platelet activation exemplified by secretion, aggregation, spreading and adhesion on fibrinogen, and tyrosine phosphorylation. αIIbβ3-dependent outside-in signal transduction induced by LSARLAF was investigated in variant thrombasthenic platelets which lack most of the cytoplasmic domain of the integrin β3 subunit (αIIbβ3 Δ724). These studies revealed that only certain aspects of this αIIbβ3-dependent outside-in signaling were affected by the β3 truncation. Specifically, αIIbβ3 724 supported LSARLAF-induced platelet aggregation, agglutination and secretion, but failed to trigger cytoskeletal reorganization and platelet spreading on fibrinogen, despite the fact that PMA-induced non αIIbβ3 mediated signaling caused spreading of these platelets on fibrinogen. Thus, distinct domains of αIIbβ3 are required to support different aspects of LSARLAF-induced platelet activation. Furthermore, these studies suggest that not all αIIbβ3-dependent platelet responses require an intact β3 cytoplasmic tail.

scholarly journals α5β1 Integrin Controls Cyclin D1 Expression by Sustaining Mitogen-activated Protein Kinase Activity in Growth Factor-treated Cells

1999 ◽  
Vol 10 (10) ◽  
pp. 3197-3204 ◽  
Author(s):  
Kristin Roovers ◽  
Gabriela Davey ◽  
Xiaoyun Zhu ◽  
Maria Elena Bottazzi ◽  
Richard K. Assoian
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cyclin D1 ◽  
Cell Attachment ◽  
Cell Types ◽  
Mitogen Activated Protein Kinase ◽  
Protein Kinase Activity ◽  
Conditional Expression ◽  
Erk Activity ◽  
Α5β1 Integrin

Cyclin D1 expression is jointly regulated by growth factors and cell adhesion to the extracellular matrix in many cell types. Growth factors are thought to regulate cyclin D1 expression because they stimulate sustained extracellular signal-regulated kinase (ERK) activity. However, we show here that growth factors induce transient ERK activity when added to suspended fibroblasts and sustained ERK activity only when added to adherent fibroblasts. Cell attachment to fibronectin or anti-α5β1 integrin is sufficient to sustain the ERK signal and to induce cyclin D1 in growth factor-treated cells. Moreover, when we force the sustained activation of ERK, by conditional expression of a constitutively active MAP kinase/ERK kinase, we overcome the adhesion requirement for expression of cyclin D1. Thus, at least in part, fibroblasts are mitogen and anchorage dependent, because integrin action allows for a sustained ERK signal and the expression of cyclin D1 in growth factor-treated cells.

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