Agonist-stimulated cytoskeletal reorganization and signal transduction at focal adhesions in vascular smooth muscle cells require c-Src

Ishida, Takafumi; Ishida, Mari; Suero, James; Takahashi, Masafumi; Berk, Bradford C.

doi:10.1172/jci4189

Cited by 155 publications

(127 citation statements)

References 43 publications

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“…The focal adhesion complex is a highly organized site at which the actin cytoskeleton attaches indirectly, through the proteins vinculin, paxillin, and talin, to aggregates of transmembrane heterodimeric ␣-and ␤-integrins (13). It has been shown that the activated AT 1 R stimulates focal adhesion complex formation and cytoskeletal reorganization (14).…”

mentioning

confidence: 99%

Cholesterol Depletion Inhibits Epidermal Growth Factor Receptor Transactivation by Angiotensin II in Vascular Smooth Muscle Cells

Ushio‐Fukai¹,

Hilenski²,

Santanam³

et al. 2001

Journal of Biological Chemistry

187

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Angiotensin II (Ang II) induces transactivation of the epidermal growth factor (EGF) receptor (EGF-R), which serves as a scaffold for various signaling molecules in vascular smooth muscle cells (VSMCs). Cholesterol and sphingomyelin-enriched lipid rafts are plasma membrane microdomains that concentrate various signaling molecules. Caveolae are specialized lipid rafts that are organized by the cholesterol-binding protein, caveolin, and have been shown to be associated with EGF-Rs. Angiotensin II stimulation promotes a rapid movement of AT 1 receptors to caveolae; however, their functional role in angiotensin II signaling has not been elucidated. Here we show that cholesterol depletion by ␤-cyclodextrin disrupts caveolae structure and concomitantly inhibits tyrosine phosphorylation of the EGF-R and subsequent activation of protein kinase B (PKB)/Akt induced by angiotensin II. Similar inhibitory effects were obtained with other cholesterol-binding agents, filipin and nystatin. In contrast, EGF-R autophosphorylation and activation of Akt/PKB in response to EGF are not affected by cholesterol depletion. The early Ang II-induced upstream signaling events responsible for transactivation of the EGF-R, such as the intracellular Ca 2؉ increase and c-Src activation, also remain intact. The EGF-R initially binds caveolin, but these two proteins rapidly dissociate following angiotensin II stimulation during the time when EGF-R transactivation is observed. The activated EGF-R is localized in focal adhesions together with tyrosinephosphorylated caveolin. These findings suggest that 1) a scaffolding role of caveolin is essential for EGF-R transactivation by angiotensin II and 2) cholesterol-rich microdomains as well as focal adhesions are important signal-organizing compartments required for the spatial and temporal organization of angiotensin II signaling in VSMCs.Angiotensin II (Ang II) 1 is a highly pluripotential hormone in vascular smooth muscle cells (VSMCs) and stimulates multiple signaling pathways, including Src family kinases, as well as mitogen-activated protein kinases (MAPKs) and Akt/protein kinase B (PKB), that mediate VSMC hypertrophy and growth via AT 1 receptors (AT 1 Rs). Increasing evidence suggests that transmodulation of the epidermal growth factor receptor (EGF-R), which serves as a scaffold for various signaling molecules, plays an essential role in organizing Ang II-mediated tyrosine kinase signaling pathways. We and others (1, 2) have demonstrated that EGF-R transactivation by Ang II is mediated through Ca 2ϩ , c-Src, and NADPH oxidase-derived reactive oxygen species, leading to activation of downstream signaling such as extracellular signal regulated kinase (ERK) and Akt/ PKB in VSMCs.Relatively little is known of the mechanisms controlling the spatial and temporal organization of AT 1 R signaling in VSMCs or of how specificity is achieved. We showed originally that Ang II signaling in VSMC is biphasic and that internalization or sequestration of the agonist-occupied receptor into a "signaling domain" ...

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mentioning

confidence: 99%

Cholesterol Depletion Inhibits Epidermal Growth Factor Receptor Transactivation by Angiotensin II in Vascular Smooth Muscle Cells

Ushio‐Fukai¹,

Hilenski²,

Santanam³

et al. 2001

Journal of Biological Chemistry

187

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“…Overall, it can be concluded that the induction of Cas phosphorylation by TGF-␤ is dependent on E-cadherin-mediated cell-cell interaction and independent of the cell-ECM adhesion. However, considering that a variety of the stimuli leading to the stimulation of tyrosine phosphorylation of Cas have been shown to induce a rapid increase in stress fibers and in focal adhesions (19,51,70) and that we cannot rule out the possibility that the HaCaT cells in our study may not be suitable in staining for focal plaques and F-actin, further study is required to elucidate the exact mechanism of integrin-independent Cas phosphorylation in the early event of TGF-␤ signaling.…”

Section: Discussionmentioning

confidence: 94%

Involvement of Cell-Cell Interactions in the Rapid Stimulation of Cas Tyrosine Phosphorylation and Src Kinase Activity by Transforming Growth Factor-β1

Kim

Joo

2002

Journal of Biological Chemistry

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Transforming growth factor-␤ (TGF-␤) regulates a wide range of physiological and pathological cellular processes, including cell migration, mesenchymal transition, extracellular matrix synthesis, and cell death. Cas (Crk-associated substrate, 130 kDa), an adaptor protein localized at focal adhesions and stress fibers, is also known to have important functions in cell migration and the induction of immediate-early gene expression. Here, we report that a rapid and transient tyrosine phosphorylation of Cas is induced by TGF-␤1 and that E-cadherin-mediated cell-cell interaction and the Src kinase pathway are involved in this early TGF-␤ signaling. The addition of TGF-␤1 to epithelial cells rapidly induced tyrosine phosphorylation of Cas and promoted the formation of complexes between focal adhesion molecules. Cas phosphorylation required the integrity of the actin cytoskeleton but was not dependent on cell adhesion, implying that Cas-dependent signaling may be distinct from integrin signaling. TGF-␤1 also stimulated Src kinase activity, and specific inhibitors of Src completely blocked the induction of Cas phosphorylation by TGF-␤1. The Cas phosphorylation and Src kinase activation seen in our results were induced in an epithelial phenotype-specific manner. Stable transfection of E-cadherin to L929 cells and L cells as well as E-cadherin blocking assay revealed that E-cadherin-mediated cellcell interactions were essential for both Cas phosphorylation and Src kinase activation. Taken together, our data suggest that rapid Cas phosphorylation and Src kinase activation may play a novel role in TGF-␤ signal transduction. Transforming growth factor-␤ (TGF-␤)1 regulates a wide range of physiological and pathological cellular processes, including differentiation, immune response, inflammation, extracellular matrix synthesis, angiogenesis, and wound healing in humans (1-3). In epithelial and endothelial cells, TGF-␤ strongly inhibits cell growth (4, 5) and, in fibroblasts, acts in both growth stimulatory and growth inhibitory manners depending on the stage of differentiation and culture conditions (6, 7). TGF-␤ exhibits a tumor suppressor activity, and components of its signaling pathway are frequently mutated or silenced in colon and pancreatic cancers (8). However, accumulating data indicate that TGF-␤ can positively affect tumorigenesis and contribute to the progression and invasiveness of tumors (9 -11). This tumor-activating activity of TGF-␤ is associated with its ability to induce an epithelial to mesenchymal transition and stimulate cell migration (12). The epithelial to mesenchymal transition induced by TGF-␤ results in the disruption of the polarized morphology of epithelial cells, the formation of stress fibers, and an enhancement of cell migration (11, 13-15).The cell migration and reorganization of the actin cytoskeleton induced by many extracellular factors are accompanied by dramatic changes in the tyrosine phosphorylation of several signaling proteins localized at the focal adhesion plaques (16,17). The rapid...

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“…For example, cells plated on rigid substrates have more robust adhesions than those on more flexible substrates [15][16][17], presumably because rigid substrates are more capable of resisting the contractile forces from the cell. Likewise, cells treated with agents that increase actinomyosin contractility such as Lysophosphatidic acid (LPA), thrombin, or bombesin also lead to a further increase in FA size in cells plated on rigid substrates [18,19]. This is mediated by activation of the Rho pathway, which stimulates actinomyosin contractility, leading to FA growth [20].…”

Section: Adhesion and The Development Of Tensionmentioning

confidence: 99%

Focal adhesion kinase as a regulator of cell tension in the progression of cancer

Tilghman¹,

Parsons²

2008

Seminars in Cancer Biology

144

115

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Growing evidence indicates that critical steps in cancer progression such as cell adhesion, migration, and cell cycle progression are regulated by the composition and organization of the microenvironment. The adhesion of cancer cells to components of the microenvironment and the forces transmitted to the cells via the actinomyosin network and the signaling complexes organized within focal adhesions allow cancer cells to sense the local topography of the extracellular matrix and respond efficiently to proximal growth and migration promoting cues. Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that is over expressed in a variety of cancers and plays an important role in cell adhesion, migration, and anchorage-dependent growth. In this review, we summarize evidence which implicate FAK in the ability of cells to sense and respond to local forces from the microenvironment through the regulation of adhesion dynamics and actinomyosin contractility, and we discuss the potential roles of FAK as a mechanosensor in the progression of cancer.

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Agonist-stimulated cytoskeletal reorganization and signal transduction at focal adhesions in vascular smooth muscle cells require c-Src

Cited by 155 publications

References 43 publications

Cholesterol Depletion Inhibits Epidermal Growth Factor Receptor Transactivation by Angiotensin II in Vascular Smooth Muscle Cells

Cholesterol Depletion Inhibits Epidermal Growth Factor Receptor Transactivation by Angiotensin II in Vascular Smooth Muscle Cells

Involvement of Cell-Cell Interactions in the Rapid Stimulation of Cas Tyrosine Phosphorylation and Src Kinase Activity by Transforming Growth Factor-β1

Focal adhesion kinase as a regulator of cell tension in the progression of cancer

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