DrosophilaVps35 function is necessary for normal endocytic trafficking and actin cytoskeleton organisation

Abstract

To identify novel proteins required for receptor-mediated endocytosis, we have developed an RNAi-based screening method in Drosophila S2 cells, based on uptake of a scavenger receptor ligand. Some known endocytic proteins are essential for endocytosis in this assay, including clathrin and α-adaptin; however, other proteins important for synaptic vesicle endocytosis are not required. In a small screen for novel endocytic proteins, we identified the Drosophila homologue of Vps35, a component of the retromer complex, involved in endosome-to-Golgi trafficking. Loss of Vps35 inhibits scavenger receptor ligand endocytosis, and causes mislocalisation of a number of receptors and endocytic proteins. Vps35 has tumour suppressor properties because its loss leads to overproliferation of blood cells in larvae. Its loss also causes signalling defects at the neuromuscular junction, including upregulation of TGFβ/BMP signalling and excessive formation of synaptic terminals. Vps35 negatively regulates actin polymerisation, and genetic interactions suggest that some of the endocytic and signalling defects of vps35 mutants are due to this function.

Interplay between Rab5 and PtdIns(4,5)P2 controls early endocytosis in theDrosophilagermline

“…Furthermore, we report here a situation different from that in neurons, where removing PtdIns(4,5)P 2 from endosomal membrane does not require Synj. The finding also echoes the recent observation that Synj is not required for endocytosis in S2 cells (Korolchuk et al, 2007). Altogether, this suggests that different enzymes could fulfill this function in various cell types.…”

BMP signaling requires retromer-dependent recycling of the type I receptor

“…Although a recent study failed to show a VPS35 RNAi effect in Madin-Darby canine kidney cells on TGFβR1(ALK5) (34), they did demonstrate that TGFβRII was mislocalized to both the basolateral and apical membrane, as opposed to its normal localization to the basolateral membrane. Examination of the role of the retromer complex on BMP signaling in Drosophila has been incongruent (27,35,36). On the basis of our genetic and cell biological data, as well as the preliminary data from the mammalian proteomic analysis, it is very likely that retromer-dependent regulation of type I BMP and Activin receptors is a conserved mechanism of TGFβ-receptor regulation.…”

Flies with Parkinson's disease

“…Yes (Belenkaya et al, 2008;Franch-Marro et al, 2008;Korolchuk et al, 2007;Port et al, 2008) Yes (Belenkaya et al, 2008;S. Wang et al, 2014) Yes (P316S⁎-D620N⁎-L774M⁎ (H.-S. )…”

“…In recent years a role for vesicle trafficking has emerged and several of the genes involved in PD have been suggested to play an active role in the process. Alphasynuclein, LRRK2, Vps35, Synaptojanin, Parkin and DNAJC6/auxillin are directly connected to the process and several of these proteins have been extensively studied in fruit flies (Dodson et al, 2014;Korolchuk et al, 2007;Linhart et al, 2014;MacLeod et al, 2013). Interestingly, work in Drosophila is also helping to start elucidating the connections between these different players; e.g.…”