Non-apoptotic function of caspase-3 in morphogenesis of epithelial tubes of Drosophila renal system

Cells trigger apoptosis to eliminate themselves from the system, when tissue needs to be sculptured or they detect any abnormality within them, thus preventing irreparable damage to the host. Drosophila Malpighian tubules express apoptotic proteins, without succumbing to cell death. Here we present evidence to show apoptosis independent role of executioner caspase, Drice, for precise architecture and function of Malpighian tubules. Drice is required for precise cytoskeleton organization and convergent extension, failing which the morphology, size, cellular number and arrangement gets affected. Acquisition of star shape of stellate cells in adult Malpighian tubules requires Drice. We demonstrate that Drice regulates expression of Rho1GTPase and localization of polarity proteins. Our study shows a probable mechanism by which Drice governs tubulogenesis via Rho1GTPase mediated coordinated organization of actin cytoskeleton and membrane stablisation. Furthermore, defective morphology of tubules leads to abnormal osmoregulation and excretory functions. Collectively our findings suggest a possible non-apoptotic function of caspase-3 in the fine tuning of cell mobility during tubule development and our results will add to the growing understanding of diverse roles of caspases during its evolution in metazoans.