The branching code: A model of actin-driven dendrite arborization

Nascent dendrite branches initiated by a localized burst of Spire-dependent actin polymerization

“…It may require stoichiometric amounts of additional partners 14 to engage the switch that signals the initiation step. The KIND domain mutation Y232K is known to abolish the interaction between Spir and Capu, and there is some genetic evidence that Spir and Capu interact for dendrite branching in class 3 da (c3da) neurons (Sturner et al, 2022), but it remains unclear whether Capu is required in c4da neurons for dendrite arborization. In unpublished data, we built a capu GAL4 line that did not label c4da neurons, and RNAi lines targeting Capu did not reduce terminal branch number when expressed in c4da neurons.…”

“…Dendrite filopodia are structurally distinct from conventional filopodia, with an unusual network-like cytoskeletal organization characterized by both branched and linear filaments of mixed polarity (Korobova and Svitkina, 2010), suggesting involvement of multiple actin regulatory proteins with distinct activities. Few studies have identified specific actin regulators involved in forming new branches (Hou et al, 2015; Nithianandam and Chien, 2018; Shi et al, 2021; Sturner et al, 2022; Sturner et al, 2019; Zou et al, 2018), and none have pinpointed their regulation of actin to the location and timing of nascent branch outgrowth. In sensory neurons of living Drosophila larvae, the locations of dendrite filopodia initiation sites are pre-figured by patches of actin polymer (Andersen et al, 2005; Nithianandam and Chien, 2018; Sturner et al ., 2019), as has been proposed for dendrite filopodia in the mouse brain also (Willig et al, 2014).…”

“…Few studies have identified specific actin regulators involved in forming new branches (Hou et al, 2015;Nithianandam and Chien, 2018;Shi et al, 2021;Sturner et al, 2022;Sturner et al, 2019;Zou et al, 2018), and none have pinpointed their regulation of actin to the location and timing of nascent branch outgrowth. In sensory neurons of living Drosophila larvae, the locations of dendrite filopodia initiation sites are pre-figured by patches of actin polymer (Andersen et al, 2005;Nithianandam and Chien, 2018;Sturner et al, 2019), as has been proposed for dendrite filopodia in the mouse brain also (Willig et al, 2014).…”

Brain-wide dendrites in a near-optimal performance of dynamic range and information transmission

“…Dendrites achieve near-optimal performance when soma bifurcates to some intermediate number of branches. Such intermediate number of somatic branches can also be understood by optimal rewiring between given branching points [6,7]; a large number of somatic branches would result in a large path length in dendrites and optimal wiring between branching points would result in an intermediate number of somatic branches.…”

“…Computational models have been developed and proposed to describe complex dendritical structures [1,2,3,4,5]. Optimization models have also been developed to understand intrinsic mechanism underling branching; see [6,7,8] and references therein. It is suggested dendrites grow to fill a target space in an optimal manner, using the least amount of wiring to reach all synaptic contacts.…”