Toxoplasma gondiidisrupts β1 integrin signaling and focal adhesion formation during monocyte hypermotility

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 Integrin-specific signaling pathways controlling focal adhesion formation and cell migration.

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

10.3410/f.1013023.188454 ◽

2003 ◽

Author(s):

Dietmar Vestweber

Keyword(s):

Cell Migration ◽

Signaling Pathways ◽

Focal Adhesion ◽

Adhesion Formation ◽

Focal Adhesion Formation

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A feedback-loop extended stress fiber growth model with focal adhesion formation

International Journal of Solids and Structures ◽

10.1016/j.ijsolstr.2017.08.023 ◽

2017 ◽

Vol 128 ◽

pp. 160-173 ◽

Cited By ~ 1

Author(s):

Pradeep Keshavanarayana ◽

Martin Ruess ◽

René de Borst

Keyword(s):

Growth Model ◽

Focal Adhesion ◽

Feedback Loop ◽

Adhesion Formation ◽

Stress Fiber ◽

Fiber Growth ◽

Focal Adhesion Formation

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Cell Adhesion-dependent Serine 85 Phosphorylation of Paxillin Modulates Focal Adhesion Formation and Haptotactic Migration via Association with the C-terminal Tail Domain of Talin

Journal of Biological Chemistry ◽

10.1074/jbc.m111.323360 ◽

2012 ◽

Vol 287 (33) ◽

pp. 27499-27509 ◽

Cited By ~ 11

Author(s):

Tae Kyoung Kwak ◽

Mi-Sook Lee ◽

Jihye Ryu ◽

Yoon-Ju Choi ◽

Minkyung Kang ◽

...

Keyword(s):

Cell Adhesion ◽

Focal Adhesion ◽

Adhesion Formation ◽

Tail Domain ◽

Focal Adhesion Formation

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Abstract 110: Thrombospondin Type-1 Domain-Containing Protein 1 (THSD1), an Intracranial Aneurysm Susceptibility Gene, Mediates Cell Adhesion in Human Umbilical Vein Endothelial Cells

Stroke ◽

10.1161/str.46.suppl_1.110 ◽

2015 ◽

Vol 46 (suppl_1) ◽

Author(s):

Xiaoqian Fang ◽

Dong H Kim ◽

Teresa Santiago-Sim

Keyword(s):

Endothelial Cells ◽

Cell Adhesion ◽

Focal Adhesion ◽

Umbilical Vein ◽

Adhesion Formation ◽

Wild Type ◽

Focal Adhesion Formation ◽

Umbilical Vein Endothelial Cells

Introduction: An intracranial aneurysm (IA) is a weak spot in cerebral blood vessel wall that can lead to its abnormal bulging. Previously, we reported that mutations in THSD1 , encoding thrombospondin type-1 domain-containing protein 1, are associated with IA in a subset of patients. THSD1 is a transmembrane molecule with a thrombospondin type-1 repeat (TSR). Proteins with TSR domain have been implicated in a variety of processes including regulation of matrix organization, cell adhesion and migration. We have shown that in mouse brain Thsd1 is expressed in endothelial cells. Hypothesis: THSD1 plays an important role in maintaining the integrity of the endothelium by promoting adhesion of endothelial cells to the underlying basement membrane. Methods: Human umbilical vein endothelial cells are used to investigate the role of THSD1 in vitro . THSD1 expression was knocked-down by RNA interference. Cell adhesion assay was done on collagen I-coated plates and focal adhesion formation was visualized using immunofluorescence by paxillin and phosphorylated focal adhesion kinase (pFAK) staining. THSD1 re-expression is accomplished by transfection with a pCR3.1-THSD1-encoding plasmid. Results: Knockdown of THSD1 caused striking change in cell morphology and size. Compared to control siRNA-treated cells that exhibited typical cobblestone morphology, THSD1 knockdown cells were narrow and elongated, and were significantly smaller ( p <0.01). Cell adherence to collagen I-coated plates was also attenuated in THSD1 knockdown cells ( p <0.01). Consistent with this finding is the observation that the number and size of focal adhesions, based on paxillin and pFAK staining, were significantly reduced after THSD1 knockdown ( p <0.01). These defects in cell adhesion and focal adhesion formation were rescued by re-expression of wild type THSD1 ( p <0.05). In contrast, initial studies indicate that expression of mutated versions of THSD1 as seen in human patients (L5F, R450*, E466G, P639L) could not restore cell adhesion and focal adhesion formation to wild type levels. Conclusions: Our studies provide evidence for a role of THSD1 and THSD1 mutations in endothelial cell adhesion and suggest a possible mechanism underlying THSD1 -mediated aneurysm disease.

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