A typical example is stereotyped removal of axonal branches in layer 5 cortical neurons at an early postnatal stage in rats ( Stanfield et al., 1982). In vertebrates, neurons first develop exuberant connections with many targets at embryonic stages and eliminate improper ones postnatally to establish functional connectivity ( Schuldiner and Yaron, 2015). Pruning is a highly conserved process during the development of nervous systems in both vertebrates and invertebrates. One of such strategies is pruning that eliminates unnecessary neurites and connections, without causing neuronal death at a later developmental stage ( Luo and O'Leary, 2005 Yaniv and Schuldiner, 2016 Yu and Schuldiner, 2014). Finally, our data reveal that ER-to-Golgi transport promotes endocytosis and downregulation of the cell-adhesion molecule Neuroglian and thereby dendrite pruning.ĭuring animal development, neurons generate excessive cellular processes and connections at an earlier stage, and subsequently achieve accurate wiring via several regressive strategies ( Schuldiner and Yaron, 2015). Moreover, we show that two GTPases, Rab1 and Sar1, which are known to regulate ER-to-Golgi transport, are essential for dendrite pruning of ddaC neurons. Yip1 and Yif1 colocalize on ER/Golgi and are required for the integrity of Golgi apparatus and outposts. Yif1 forms a protein complex with Yip1 in S2 cells and ddaC neurons. We further identify that the Yif1-binding partner Yip1 is also crucial for dendrite pruning. We show that Yif1 is required for dendrite pruning of ddaC neurons but not for apoptosis of ddaF neurons. Here, in a clonal screen, we have identified Yif1, an uncharacterized Drosophila homolog of Yif1p that is known to be a regulator of ER-to-Golgi transport in yeast. However, the important role of endoplasmic reticulum (ER)-to-Golgi transport in dendrite pruning remains unknown. In Drosophila, ddaC sensory neurons specifically prune their larval dendrites with intact axons during metamorphosis. Research was supported by grants from the US National Institutes of Health (NS-029971), the Medical Research Council and the CREST program of the Japan Science and Technology Agency.Pruning that selectively removes unnecessary neurites without causing neuronal death is essential for sculpting the mature nervous system during development. Miyawaki (RIKEN Brain Science Institute, Saitama, Japan) for plasmids and S. Freeman (University of Massachusetts Medical School, Worcester, Massachusetts) and the Bloomington Drosophila Stock Center at Indiana University for fly stocks A. McNabb (University of Washington, Seattle), M. Johnson (University of Iowa, Iowa City, Iowa), G. Abrams (University of Texas/Southwestern Medical Center, Dallas), W. Grueber (Columbia University, New York), J. Meier (Institute of Cancer Research, London), W. Kumar (Hanson Institute and Institute of Medical and Veterinary Science Adelaide, Australia), P. Baehrecke (University of Maryland Biotechnology Institute, College Park, Maryland), S. Awasaki for informing us about the second site mutation on the draper Δ5 chromosome E. Watts, R.J., Schuldiner, O., Perrino, J., Larsen, C.
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