ESCRT Proteins Control the Dendritic Morphology of Developing and Mature Hippocampal Neurons

Abstract

The proper shape of dendritic arbors of different types of neurons determines their proper communication within neuronal networks. The shape of dendritic arbors is acquired during a complex and multistep process called dendritogenesis. In most cases, once proper morphology is achieved, it remains stable throughout the lifespan, with the exception of rare events during which dendrites are abruptly pruned. The endosomal sorting complex required for transport (ESCRT) is multisubunit machinery that is involved in various cellular processes when membrane scission is needed. ESCRT subcomplexes regulate dendrite pruning in Drosophila neurons. However, the contribution of ESCRT components to the dendritogenesis of mammalian neurons and control of dendrite stability remains poorly defined. In the present study, we found that ESCRT-0, ESCRT-I, ESCRT-II, and ESCRT-III and Vps4 are required for proper dendrite morphology under basal culture conditions and for accelerated dendritogenesis in response to phosphoinositide 3-kinase (PI3K) activation. The knockdown of Vps28 (ESCRT-I) and Vps25 (ESCRT-II) resulted in downregulation of the activity of mechanistic/mammalian target of rapamycin complex 1. We also demonstrated that Vps28, Vps24, and Vps25 are required for dendrite stabilization in mature neurons. Electronic supplementary material The online version of this article (10.1007/s12035-018-1418-9) contains supplementary material, which is available to authorized users.

Genetic analysis of the Drosophila ESCRT-III complex protein, VPS24, reveals a novel function in lysosome homeostasis

“…Some autophagic intermediates were associated with spherical autolysosome structures ( Fig 10Ab , S10 Fig ), raising the possibility that lysophagy was disrupted in the vps24 mutant. Finally, the vps24 mutant did not exhibit ultrastructural features characteristic of accumulated late endosomes/MVBs [ 73 , 74 ], consistent with previous studies suggesting that VPS24 may be dispensable for MVB formation [ 14 , 27 , 28 ]. These ultrastructural studies confirm that loss of VPS24 function results in expansion of the lysosomal compartment and disruption of autophagy.…”

“…accumulated late endosomes/MVBs [73,74], consistent with previous studies suggesting that VPS24 may be dispensable for MVB formation [14,27,28]. These ultrastructural studies confirm that loss of VPS24 function results in expansion of the lysosomal compartment and disruption of autophagy.…”

A conserved ubiquitin- and ESCRT-dependent pathway to regulate human lysosomal membrane proteins

“…To ensure the siRNA knockdown methods can truly disrupt the function of ESCRT machinery, we stained the cells with the FK2 antibody that specifically recognizes poly-ubiquitinated proteins (Firkowska et al, 2019). Since ESCRT machinery is responsible for internalizing ubiquitinated proteins from the endosome membrane, depleting ESCRT components will lead to the accumulation of poly-ubiquitinated proteins at the endosome surface.…”

Homeostatic Roles of the Proteostasis Network in Dendrites

“…Based on these patterns of movement, and common mixed polarity microtubule organization in mammals, it appears that autophagosome transport is dependent on microtubules and retrograde motors, such as dynein (Yang et al, 2013;Holzbaur, 2014, 2016). Endosomes, which also appear to depend on dynein for transport, have been found to traffic bidirectionally in dendrites, as have lysosomes (Satoh et al, Lu et al, 2009 SkpA KD Wong et al, 2013;Das et al, 2017;Nanda et al, 2018 APC KD Kim et al, 2009 Highwire LOF mutant Wang et al, 2013SCF KD Wong et al, 2013 Impaired dendritic pruning Cullin1 KD Wong et al, 2013 Impaired dendritic pruning Roc1a KD Wong et al, 2013 Impaired dendritic pruning Slimb KD Wong et al, 2013 Impaired dendritic pruning Rab5 KD Reduced dendritic arbor Impaired dendritic pruning during pupation Satoh et al, 2008;Zhang et al, 2014 Rab11 KD Reduced dendritic arbor Impaired dendritic pruning during pupation Krämer et al, 2019;Siri et al, 2020 ESCRT complex KD Reduced dendritic arbor Impaired dendritic pruning during pupation Zhang et al, 2014;Firkowska et al, 2019HRD1 KD Saldate et al, 2018 Nedd4 KO Kawabe et al, 2010 Atg7 KD in microglia Kim et al, 2017 Only proteins that directly affect dendritic arbor morphology are listed, in the order found in the text. 2008;Jin et al, 2018;Yap et al, 2018).…”

“…The small GTPase Rab5, a component of the early endocytic pathway, has been shown to associate with cytoplasmic Dynein to promote dendritic branching (Satoh et al, 2008). Furthermore, components of the endosomal sorting complex required for transport (ESCRT) machinery have been implicated in regulating dendritic growth (Sweeney et al, 2006;Firkowska et al, 2019). Finally, the recycling endosome marker Rab11 has been implicated in proper dendritic arbor formation in Drosophila larvae and rat hippocampal neurons (Krämer et al, 2019;Siri et al, 2020).…”