Phosphorylation of paxillin via the ERK mitogen-activated protein kinase cascade in EL4 thymoma cells.

Abstract

Intracellular signals can regulate cell adhesion via several mechanisms in a process referred to as "inside-out" signaling. In phorbol ester-sensitive EL4 thymoma cells, phorbol-12-myristate 13-acetate (PMA) induces activation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases and promotes cell adhesion. In this study, clonal EL4 cell lines with varying abilities to activate ERKs in response to PMA were used to examine signaling events occurring downstream of ERK activation. Paxillin, a multifunctional docking protein involved in cell adhesion, was phosphorylated on serine/threonine residues in response to PMA treatment. This response was correlated with the extent and time course of ERK activation. PMA-induced phosphorylation of paxillin was inhibited by compounds that block the ERK activation pathway in EL4 cells, primary murine thymocytes, and primary murine splenocytes. Paxillin was phosphorylated in vitro by purified active ERK2. Two-dimensional electrophoresis revealed that PMA treatment generated a complex pattern of phosphorylated paxillin species in intact cells, some of which were generated by ERK-mediated phosphorylation in vitro. An ERK pathway inhibitor interfered with PMA-induced adhesion of sensitive EL4 cells to substrate. These findings describe a novel inside-out signaling pathway by which the ERK cascade may regulate events involved in adhesion.

• Authors: H Ku, K E Meier
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 275 Issue 15 Pg. 11333-40 (Apr 14 2000) ISSN: 0021-9258 [Print] United States
• PMID: 10753946 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Cytoskeletal Proteins
• Paxillin
• Phosphoproteins
• Pxn protein, mouse
• Protein-Tyrosine Kinases
• Mitogen-Activated Protein Kinases
• Protein Tyrosine Phosphatases
• Tetradecanoylphorbol Acetate

Topics

• Animals
• Cell Adhesion (drug effects)
• Cytoskeletal Proteins (metabolism)
• Mice
• Mitogen-Activated Protein Kinases (physiology)
• Paxillin
• Phosphoproteins (metabolism)
• Phosphorylation
• Protein Tyrosine Phosphatases (physiology)
• Protein-Tyrosine Kinases (physiology)
• T-Lymphocytes (metabolism)
• Tetradecanoylphorbol Acetate (pharmacology)
• Thymoma (metabolism, pathology)
• Tumor Cells, Cultured