TSC2 modulates actin cytoskeleton and focal adhesion through TSC1-binding domain and the Rac1 GTPase

• Published in: The Journal of cell biology Vol. 167; no. 6; pp. 1171 - 1182
• Main Authors: Goncharova, Elena, Goncharov, Dmitry, Noonan, Daniel, Krymskaya, Vera P
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 20.12.2004; The Rockefeller University Press
• Subjects: 3T3 Cells; Actins; Actins - metabolism; Adhesion; Animals; Antibodies; Cell adhesion & migration; Cell Adhesion - drug effects; Cell Adhesion - physiology; Cell Line, Tumor; Cell motility; Cellular biology; Cytoskeleton - metabolism; Cytoskeleton - physiology; Deregulation; Down-Regulation; Fibers; Focal adhesions; Gene expression regulation; Mice; Plasmids; Proteins; Proteins - antagonists & inhibitors; Proteins - genetics; Proteins - metabolism; rac1 GTP-Binding Protein - antagonists & inhibitors; rac1 GTP-Binding Protein - metabolism; Rats; Renovations; Repressor Proteins - genetics; Repressor Proteins - metabolism; Repressor Proteins - pharmacology; rho GTP-Binding Proteins - antagonists & inhibitors; rho GTP-Binding Proteins - metabolism; RNA, Small Interfering - genetics; Small interfering RNA; Stress fibers; Tuberous Sclerosis Complex 1 Protein; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.200405130

Tuberous sclerosis complex (TSC) 1 and TSC2 are thought to be involved in protein translational regulation and cell growth, and loss of their function is a cause of TSC and lymphangioleiomyomatosis (LAM). However, TSC1 also activates Rho and regulates cell adhesion. We found that TSC2 modulates actin dynamics and cell adhesion and the TSC1-binding domain (TSC2-HBD) is essential for this function of TSC2. Expression of TSC2 or TSC2-HBD in TSC2-/- cells promoted Rac1 activation, inhibition of Rho, stress fiber disassembly, and focal adhesion remodeling. The down-regulation of TSC1 with TSC1 siRNA in TSC2-/- cells activated Rac1 and induced loss of stress fibers. Our data indicate that TSC1 inhibits Rac1 and TSC2 blocks this activity of TSC1. Because TSC1 and TSC2 regulate Rho and Rac1, whose activities are interconnected in a reciprocal fashion, loss of either TSC1 or TSC2 function may result in the deregulation of cell motility and adhesion, which are associated with the pathobiology of TSC and LAM.