Role of twinstar(Tsr) in regulation of dTCTP , Hippo and JNK signaling in drosophila

Abstract

Actin cytoskeleton is important for the regulation of tissue growth. It has been shown in Drosophila that an abnormal accumulation of F-actin can induce strong overgrowth in wing imaginal discs through modulating the activity of the Hippo signaling pathway. We have found that Twinstar (Tsr), which prevents the extension of barbed ends of actin filaments, also functions to regulate tissue growth by affecting the Hippo pathway. Loss of Tsr activity results in accumulation of F-actin and JNK-mediated apoptosis. It also affects the expression of Hippo downstream genes, cell proliferation and cell junction proteins in the wing disc. These findings imply genetic interactions between Tsr activity and Hippo pathway activity that is essential for normal growth control. Cytoskeleton regulation and JNK-Matrix Metalloproteases (MMP) signaling are important factors in cell migration. Tsr reduction by RNAi knockdown induced atypical cell migration in wing discs. It also caused Rho1 mislocalization and junction protein disruption. It has been suggested that Translationally Controlled Tumor Protein (TCTP) is a cytoskeleton regulator by stabilizing microtubule, binding to ADP-G-actin. We show that the expression level and the localization of Drosophila TCTP (dTCTP) are modulated by Tsr function. Taken together, these findings indicate that cytoskeleton regulation by Tsr is important for growth and cell migration by affecting multiple signaling pathways like Hippo, JNK and TOR signaling.