The small GTPases of the Rac/Rho/Cdc42 subfamily are implicated in actin cytoskeleton-membrane interaction in mammalian cells and budding yeast. The in vivo functions of these GTPases in multicellular organisms are not known. We have cloned Drosophila homologs of rac and CDC42, Drac1, and Dcdc42. They share 70% amino acid sequence identity with each other,… (More)
Neurons contain distinct compartments including dendrites, dendritic spines, axons and synaptic terminals. The molecular mechanisms that generate and distinguish these compartments, although largely unknown, may involve the small GTPases Rac and Cdc42, which appear to regulate actin polymerization. Having shown that perturbations of Rac1 activity block the… (More)
Cdc42 and Rac1 are members of the rho family of small guanosinetriphosphatases and are required for a diverse set of cytoskeleton-membrane interactions in different cell types. Here we show that these two proteins contribute differently to the organization of epithelial cells in the Drosophila wing imaginal disc. Drac1 is required to assemble actin at… (More)
Rho family GTP-binding proteins regulate various aspects of the actin cytoskeleton in a wide variety of organisms. Recent evidence suggests that they may also be important components of the signalling pathways that link the reception of extracellular cues to the regulation of the cytoskeleton in neuronal growth cones.
We propose that small GTPases in the Rho/Rac/Cdc42 subfamily play a central role in signaling pathways from cell surface receptors to actin cytoskeleton changes in the growth cone. The proposal is based upon the following evidence. First, the Rho/Rac/Cdc42 subfamily GTPases have been shown to regulate various aspects of cytoskeletal organization from… (More)
Stem cell self-renewal versus differentiation is regulated by the niche, which provides localized molecules that favor self-renewal. In the Drosophila melanogaster female germline stem cell (GSC) niche, Decapentaplegic (Dpp), a fly transforming growth factor β molecule and well-established long-range morphogen, acts over one cell diameter to maintain the… (More)
Stem cell niches provide localized signaling molecules to promote stem cell fate and to suppress differentiation. The Drosophila melanogaster ovarian niche is established by several types of stromal cells, including terminal filament cells, cap cells, and escort cells (ECs). Here, we show that, in addition to its well-known function as a niche factor… (More)