Lung epithelial cell focal adhesion kinase signaling inhibits lung injury and fibrosis

Progressive pulmonary fibrosis is a devastating consequence of many acute and chronic insults to the lung. Lung injury leads to alveolar epithelial cell (AEC) death, destruction of the basement membrane, and activation of transforming growth factor-β (TGF-β). There is subsequent resolution of the injury and a coordinated and concurrent initiation of fibrosis. Both of these processes may involve activation of similar intracellular signaling pathways regulated in part by dynamic changes to the extracellular matrix. Matrix signaling can augment the profibrotic fibroblast response to TGF-β. However, similar matrix/integrin signaling pathways may also be involved in the inhibition of ongoing TGF-β-induced AEC apoptosis. Focal adhesion kinase (FAK) is an integrin-associated signaling molecule expressed by many cell types. We used mice with AEC-specific FAK deletion to isolate the epithelial aspect of integrin signaling in the bleomycin model of lung injury and fibrosis. Mice with AEC-specific deletion of FAK did not exhibit spontaneous lung injury but did have significantly greater terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling-positive cells (18.6 vs. 7.1) per ×200 field, greater bronchoalveolar lavage protein (3.2 vs. 1.8 mg/ml), and significantly greater death (77 vs. 19%) after bleomycin injury compared with littermate control mice. Within primary AECs, activated FAK directly associates with caspase-8 and inhibits activation of the caspase cascade resulting in less apoptosis in response to TGF-β. Our studies support a model in which dynamic changes to the extracellular matrix after injury promote fibroblast activation and inhibition of epithelial cell apoptosis in response to TGF-β through FAK activation potentially complicating attempts to nonspecifically target this pathway for antifibrotic therapy.

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Focal adhesion kinase signaling is decreased in polyamine-depleted IEC-6 cells

AJP Cell Physiology ◽

10.1152/ajpcell.2001.281.2.c475 ◽

2001 ◽

Vol 281 (2) ◽

pp. C475-C485 ◽

Cited By ~ 22

Author(s):

Ramesh M. Ray ◽

Mary Jane Viar ◽

Shirley A. McCormack ◽

Leonard R. Johnson

Keyword(s):

Extracellular Matrix ◽

Focal Adhesion Kinase ◽

Focal Adhesion ◽

Focal Adhesions ◽

Stress Fiber ◽

Fiber Formation ◽

Integrin Signaling ◽

Actin Stress Fiber ◽

Stress Fiber Formation ◽

And Migration

Polyamines are essential to the migration of epithelial cells in the intestinal mucosa. Cells depleted of polyamines do not attach as rapidly to the extracellular matrix and do not form the actin stress fibers essential for migration. Because both attachment and stress fiber formation depend on integrin signaling and the formation of focal adhesions, we examined these and related processes in polyamine-depleted IEC-6 cells. There was general decreased tyrosine phosphorylation of focal adhesion kinase (FAK), and, specifically, decreased phosphorylation of Tyr-925, the paxillin binding site. In control cells, FAK phosphorylation was rapid after attachment to the extracellular matrix, while attached cells depleted of polyamines had significantly delayed phosphorylation. FAK activity was also significantly inhibited in polyamine-depleted cells as was the phosphorylation of paxillin. Polyamine-depleted cells failed to spread normally after attachment, and immunocytochemistry showed little colocalization of FAK and actin compared with controls. Focal adhesion complex formation was greatly reduced in the absence of polyamines. These data suggest that defective integrin signaling may, at least in part, account for the decreased rates of attachment, actin stress fiber formation, spreading, and migration observed in polyamine-depleted cells.

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Focal adhesion kinase: at the crossroads of signal transduction

Journal of Cell Science ◽

10.1242/jcs.110.4.401 ◽

1997 ◽

Vol 110 (4) ◽

pp. 401-407 ◽

Cited By ~ 16

Author(s):

D. Ilic ◽

C.H. Damsky ◽

T. Yamamoto

Keyword(s):

Signal Transduction ◽

Extracellular Matrix ◽

Cell Migration ◽

Tyrosine Kinase ◽

Focal Adhesion Kinase ◽

Signaling Pathways ◽

Focal Adhesion ◽

Nonreceptor Tyrosine Kinase ◽

Definitive Evidence ◽

Multiple Signaling

Morphogenetic processes during development, including cell migration, depend on signals from both the extracellular matrix (ECM) and soluble signaling factors. Extensive evidence has shown that the nonreceptor tyrosine kinase, focal adhesion kinase (FAK), is activated in response to both kind of signal. The most definitive evidence that FAK is directly downstream of signals initiated by the ECM comes from comparing the phenotypes of mice deficient for FAK and the ECM molecule, fibronectin: in both cases embryos die at about E8.5 and display almost identical severe vascular and other mesodermal defects. It is now clear that there are additional FAK-like proteins, indicating the existence of a FAK family. Furthermore, FAK is not located at adhesive sites in all cells where it is expressed. This, plus extensive data indicating that FAK becomes activated in response to several soluble signaling factors, suggests that the FAK family may be at the crossroads of multiple signaling pathways that affect cell and developmental processes.

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Receptor-interacting Protein Shuttles between Cell Death and Survival Signaling Pathways

Molecular Biology of the Cell ◽

10.1091/mbc.e09-06-0530 ◽

2010 ◽

Vol 21 (3) ◽

pp. 481-488 ◽

Cited By ~ 22

Author(s):

Pachiyappan Kamarajan ◽

Julius Bunek ◽

Yong Lin ◽

Gabriel Nunez ◽

Yvonne L. Kapila

Keyword(s):

Extracellular Matrix ◽

Cell Death ◽

Focal Adhesion Kinase ◽

Signaling Pathways ◽

Focal Adhesion ◽

Death Domain ◽

Reverse Effect ◽

Interacting Protein ◽

Survival Pathways ◽

Survival Signaling

Cross-talk between apoptosis and survival signaling pathways is crucial for regulating tissue processes and mitigating disease. We report that anoikis—apoptosis triggered by loss of extracellular matrix contacts—activates a CD95/Fas-mediated signaling pathway regulated by receptor-interacting protein (RIP), a kinase that shuttles between CD95/Fas-mediated cell death and integrin/focal adhesion kinase (FAK)-mediated survival pathways. RIP's death domain was critical for RIP and Fas association to mediate anoikis. Fas or RIP attenuation reduced this association and suppressed anoikis, whereas their overexpression had the reverse effect. Overexpressing FAK restored RIP and FAK association and inhibited anoikis. Thus, RIP shuttles between CD95/Fas death and FAK survival signaling to mediate anoikis.

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R-Ras Promotes Focal Adhesion Formation through Focal Adhesion Kinase and p130Cas by a Novel Mechanism That Differs from Integrins

Molecular and Cellular Biology ◽

10.1128/mcb.23.3.933-949.2003 ◽

2003 ◽

Vol 23 (3) ◽

pp. 933-949 ◽

Cited By ~ 37

Author(s):

Lina Kwong ◽

Michele A. Wozniak ◽

Asha S. Collins ◽

Siobhan D. Wilson ◽

Patricia J. Keely

Keyword(s):

Focal Adhesion Kinase ◽

Signaling Pathways ◽

Focal Adhesion ◽

Adhesion Formation ◽

Integrin Signaling ◽

Ras Signaling ◽

Pharmacological Inhibition ◽

Focal Adhesion Formation ◽

And Migration ◽

Α2β1 Integrin

ABSTRACT R-Ras regulates integrin function, but its effects on integrin signaling pathways have not been well described. We demonstrate that activation of R-Ras promoted focal adhesion formation and altered localization of the α2β1 integrin from cell-cell to cell-matrix adhesions in breast epithelial cells. Constitutively activated R-Ras(38V) dramatically enhanced focal adhesion kinase (FAK) and p130Cas phosphorylation upon collagen stimulation or clustering of the α2β1 integrin, even in the absence of increased ligand binding. Signaling events downstream of R-Ras differed from integrins and K-Ras, since pharmacological inhibition of Src or disruption of actin inhibited integrin-mediated FAK and p130Cas phosphorylation, focal adhesion formation, and migration in control and K-Ras(12V)-expressing cells but had minimal effect in cells expressing R-Ras(38V). Therefore, signaling from R-Ras to FAK and p130Cas has a component that is Src independent and not through classic integrin signaling pathways and a component that is Src dependent. R-Ras effector domain mutants and pharmacological inhibition suggest a partial role for phosphatidylinositol 3-kinase (PI3K), but not Raf, in R-Ras signaling to FAK and p130Cas. However, PI3K cannot account for the Src-independent pathway, since simultaneous inhibition of both PI3K and Src did not completely block effects of R-Ras on FAK phosphorylation. Our results suggest that R-Ras promotes focal adhesion formation by signaling to FAK and p130Cas through a novel mechanism that differs from but synergizes with the α2β1 integrin.

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Faculty Opinions recommendation of Distinct biophysical mechanisms of focal adhesion kinase mechanoactivation by different extracellular matrix proteins.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718174775.793489069 ◽

2013 ◽

Author(s):

Martin A Schwartz

Keyword(s):

Extracellular Matrix ◽

Focal Adhesion Kinase ◽

Focal Adhesion ◽

Extracellular Matrix Proteins ◽

Matrix Proteins

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Fibronectin-stimulated signaling from a focal adhesion kinase-c-Src complex: involvement of the Grb2, p130cas, and Nck adaptor proteins.

Molecular and Cellular Biology ◽

10.1128/mcb.17.3.1702 ◽

1997 ◽

Vol 17 (3) ◽

pp. 1702-1713 ◽

Cited By ~ 320

Author(s):

D D Schlaepfer ◽

M A Broome ◽

T Hunter

Keyword(s):

Focal Adhesion Kinase ◽

Focal Adhesion ◽

Intracellular Signaling ◽

Protein Tyrosine Kinase ◽

Adaptor Protein ◽

Adaptor Proteins ◽

Sh2 Domain ◽

Mitogen Activated Protein Kinase

The focal adhesion kinase (FAK), a protein-tyrosine kinase (PTK), associates with integrin receptors and is activated by cell binding to extracellular matrix proteins, such as fibronectin (FN). FAK autophosphorylation at Tyr-397 promotes Src homology 2 (SH2) domain binding of Src family PTKs, and c-Src phosphorylation of FAK at Tyr-925 creates an SH2 binding site for the Grb2 SH2-SH3 adaptor protein. FN-stimulated Grb2 binding to FAK may facilitate intracellular signaling to targets such as ERK2-mitogen-activated protein kinase. We examined FN-stimulated signaling to ERK2 and found that ERK2 activation was reduced 10-fold in Src- fibroblasts, compared to that of Src- fibroblasts stably reexpressing wild-type c-Src. FN-stimulated FAK phosphotyrosine (P.Tyr) and Grb2 binding to FAK were reduced, whereas the tyrosine phosphorylation of another signaling protein, p130cas, was not detected in the Src- cells. Stable expression of residues 1 to 298 of Src (Src 1-298, which encompass the SH3 and SH2 domains of c-Src) in the Src- cells blocked Grb2 binding to FAK; but surprisingly, Src 1-298 expression also resulted in elevated p130cas P.Tyr levels and a two- to threefold increase in FN-stimulated ERK2 activity compared to levels in Src- cells. Src 1-298 bound to both FAK and p130cas and promoted FAK association with p130cas in vivo. FAK was observed to phosphorylate p130cas in vitro and could thus phosphorylate p130cas upon FN stimulation of the Src 1-298-expressing cells. FAK-induced phosphorylation of p130cas in the Src 1-298 cells promoted the SH2 domain-dependent binding of the Nck adaptor protein to p130cas, which may facilitate signaling to ERK2. These results show that there are additional FN-stimulated pathways to ERK2 that do not involve Grb2 binding to FAK.

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Extracellular matrix in cardiovascular pathophysiology

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00631.2018 ◽

2018 ◽

Vol 315 (6) ◽

pp. H1687-H1690 ◽

Cited By ~ 4

Author(s):

Maria Bloksgaard ◽

Merry Lindsey ◽

Luis A. Martinez-Lemus

Keyword(s):

Extracellular Matrix ◽

Signaling Pathways ◽

Intracellular Signaling ◽

Physical And Mechanical Properties ◽

Disease Development ◽

Cardiovascular Development ◽

Intracellular Signaling Pathways ◽

Circulatory Physiology ◽

Activate Cell ◽

Cell Signaling Pathways

The extracellular matrix (ECM) actively participates in diverse aspects of cardiovascular development and physiology as well as during disease development and progression. ECM roles are determined by its physical and mechanical properties and by its capacity to both release bioactive signals and activate cell signaling pathways. The ECM serves as a storage depot for a wide variety of molecules released in response to injury or with aging. Indeed, there is a plethora of examples describing how cells react to or modify ECM stiffness, how cells initiate intracellular signaling pathways, and how cells respond to the ECM. This Perspectives article reviews the contributions of 21 articles published in the American Journal of Physiology-Heart and Circulatory Physiology in response to a Call for Papers on this topic. Here, we summarize the contributions of these studies focused on the cardiac and vascular ECM. We highlight the translational importance of these studies and conclude that the ECM is a critical component of both the heart and vasculature. Readers are urged to examine and learn from this special Call for Papers.

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Differential activation of focal adhesion kinase, Rho and Rac by the ninth and tenth FIII domains of fibronectin

Journal of Cell Science ◽

10.1242/jcs.112.17.2937 ◽

1999 ◽

Vol 112 (17) ◽

pp. 2937-2946

Author(s):

N.A. Hotchin ◽

A.G. Kidd ◽

H. Altroff ◽

H.J. Mardon

Keyword(s):

Growth Factor ◽

Focal Adhesion Kinase ◽

Signaling Pathways ◽

Focal Adhesion ◽

Cell Attachment ◽

Cell Types ◽

Integrin Receptors ◽

3T3 Cells ◽

Swiss 3T3 ◽

Kinase Phosphorylation

Fibronectins are widely expressed extracellular matrix ligands that are essential for many biological processes. Fibronectin-induced signaling pathways are elicited in diverse cell types when specific integrin receptors bind to the ninth and tenth FIII domains, FIII9-10. Integrin-mediated signal transduction involves activation of signaling pathways of the growth factor-dependent Ras-related small GTP-binding proteins Rho and Rac, and phosphorylation of focal adhesion kinase. We have dissected the requirement of FIII9 and FIII10 for Rho and Rac activity and phosphorylation of focal adhesion kinase in BHK fibroblasts and Swiss 3T3 cells. We demonstrate that FIII10 supports cell attachment but does not induce phosphorylation of focal adhesion kinase. In Swiss 3T3 cells, growth factor-independent phosphorylation of focal adhesion kinase and downstream adhesion events are dependent upon the presence of FIII9 in the intact FIII9-10 pair, whereas FIII10-mediated focal adhesion kinase phosphorylation requires a synergistic signal from growth factors. Furthermore, FIII10 is able to elicit cellular responses mediated by Rho, but not Rac, whereas FIII9-10 can elicit both Rho- and Rac-mediated responses. We propose that activation of specific integrin subunits by the FIII10 and FIII9-10 ligands elicits distinct signaling events. This may represent a general molecular mechanism for activation of receptor-specific signaling pathways by a multi-domain ligand.

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