Impaired Integrin-mediated Adhesion and Signaling in Fibroblasts Expressing a Dominant-negative Mutant PTP1B

@article{citeulike:2693700, abstract = {To investigate the role of nonreceptor protein tyrosine phosphatase 1B (PTP1B) in [beta]1-integrin- mediated adhesion and signaling, we transfected mouse L cells with normal and catalytically inactive forms of the phosphatase. Parental cells and cells expressing the wild-type or mutant PTP1B were assayed for (a) adhesion, (b) spreading, (c) presence of focal adhesions and stress fibers, and (d) tyrosine phosphorylation. Parental cells and cells expressing wild-type PTP1B show similar morphology, are able to attach and spread on fibronectin, and form focal adhesions and stress fibers. In contrast, cells expressing the inactive PTP1B have a spindle-shaped morphology, reduced adhesion and spreading on fibronectin, and almost a complete absence of focal adhesions and stress fibers. Attachment to fibronectin induces tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin in parental cells and cells transfected with the wild-type PTP1B, while in cells transfected with the mutant PTP1B, such induction is not observed. Additionally, in cells expressing the mutant PTP1B, tyrosine phosphorylation of Src is enhanced and activity is reduced. Lysophosphatidic acid temporarily reverses the effects of the mutant PTP1B, suggesting the existence of a signaling pathway triggering focal adhesion assembly that bypasses the need for active PTP1B. PTP1B coimmunoprecipitates with [beta]1-integrin from nonionic detergent extracts and colocalizes with vinculin and the ends of actin stress fibers in focal adhesions. Our data suggest that PTP1B is a critical regulatory component of integrin signaling pathways, which is essential for adhesion, spreading, and formation of focal adhesions. Key words: protein tyrosine phosphatase; integrins; cell-substrate adhesion; cell signaling; tyrosine phosphorylation 10.1083/jcb.143.3.861}, author = {Arregui, Carlos O. and Balsamo, Janne and Lilien, Jack }, citeulike-article-id = {2693700}, doi = {http://dx.doi.org/10.1083/jcb.143.3.861}, journal = {J. Cell Biol.}, keywords = {dye}, month = {November}, number = {3}, pages = {861--873}, posted-at = {2008-04-20 22:48:17}, priority = {2}, title = {Impaired Integrin-mediated Adhesion and Signaling in Fibroblasts Expressing a Dominant-negative Mutant PTP1B}, url = {http://dx.doi.org/10.1083/jcb.143.3.861}, volume = {143}, year = {1998} }

TY - JOUR ID - citeulike:2693700 L3 - citeulike-article-id:2693700 TI - Impaired Integrin-mediated Adhesion and Signaling in Fibroblasts Expressing a Dominant-negative Mutant PTP1B JF - J. Cell Biol. VL - 143 IS - 3 SP - 861 EP - 873 N2 - To investigate the role of nonreceptor protein tyrosine phosphatase 1B (PTP1B) in [beta]1-integrin- mediated adhesion and signaling, we transfected mouse L cells with normal and catalytically inactive forms of the phosphatase. Parental cells and cells expressing the wild-type or mutant PTP1B were assayed for (a) adhesion, (b) spreading, (c) presence of focal adhesions and stress fibers, and (d) tyrosine phosphorylation. Parental cells and cells expressing wild-type PTP1B show similar morphology, are able to attach and spread on fibronectin, and form focal adhesions and stress fibers. In contrast, cells expressing the inactive PTP1B have a spindle-shaped morphology, reduced adhesion and spreading on fibronectin, and almost a complete absence of focal adhesions and stress fibers. Attachment to fibronectin induces tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin in parental cells and cells transfected with the wild-type PTP1B, while in cells transfected with the mutant PTP1B, such induction is not observed. Additionally, in cells expressing the mutant PTP1B, tyrosine phosphorylation of Src is enhanced and activity is reduced. Lysophosphatidic acid temporarily reverses the effects of the mutant PTP1B, suggesting the existence of a signaling pathway triggering focal adhesion assembly that bypasses the need for active PTP1B. PTP1B coimmunoprecipitates with [beta]1-integrin from nonionic detergent extracts and colocalizes with vinculin and the ends of actin stress fibers in focal adhesions. Our data suggest that PTP1B is a critical regulatory component of integrin signaling pathways, which is essential for adhesion, spreading, and formation of focal adhesions. Key words: protein tyrosine phosphatase; integrins; cell-substrate adhesion; cell signaling; tyrosine phosphorylation 10.1083/jcb.143.3.861 KW - dye AU - Arregui, Carlos AU - Balsamo, Janne AU - Lilien, Jack PY - 1998/11/02/ UR - http://dx.doi.org/10.1083/jcb.143.3.861 ER -