The Rab7 effector protein RILP controls lysosomal transport by inducing the recruitment of dynein-dynactin motors (original) (raw)

Many intracellular compartments, including MHC Results and discussion RILP requires GTP-Rab7 for clustering of late endosomes class II-containing lysosomes [1], melanosomes and lysosomes around the MTOC [2], and phagosomes [3], move along microtubules Rab7 specifically associates with late endosomal/lysoin a bidirectional manner and in a stop-and-go somal compartments [8-11] and might thus regulate motor fashion due to the alternating activities of a plusprotein recruitment to these compartments. In order to end directed kinesin motor and a minus-end identify Rab7 binding proteins involved in this process, directed dynein-dynactin motor [4]. It is largely an Epstein-Barr virus-transformed human B lymphocyte unclear how motor proteins are targeted cDNA library was screened by yeast two-hybrid assay. A specifically to different compartments. Rab GTPases protein was isolated that specifically interacted with acrecruit and/or activate several proteins involved in tive, GTP bound Rab7Q67L but not with inactive, GDP membrane fusion and vesicular transport [5, 6]. They bound Rab7T23N. The same protein (called RILP) was associate with specific compartments after isolated by Cantalupo et al. [7]. When overexpressed by activation, which makes Rab GTPases ideal nuclear microinjection of cDNA in Mel JuSo cells expresscandidates for controlling motor protein binding ing MHC class II-GFP, RILP induced a collapse of class to specific membranes. We and others [7] have II-containing lysosomal compartments (see Supplemenidentified a protein, called RILP (for Rab7tary material available with this article online). This effect interacting lysosomal protein), that interacts with could be inhibited by coexpression of dominant-negative active Rab7 on late endosomes and lysosomes. Rab7T22N (see Supplementary material). Expression of Here we show that RILP prevents further cycling of the C-terminal half of RILP (denoted ⌬N) resulted in a