Functional interdependence of the actin nucleator Cobl and Cobl-like in dendritic arbor development.

Local actin filament formation is indispensable for development of the dendritic arbor of neurons. We show that, surprisingly, the action of single actin filament-promoting factors was insufficient for powering dendritogenesis. Instead, this required the actin nucleator Cobl and its only evolutionary distant ancestor Cobl-like acting interdependently.

Cobl-like promotes actin filament formation and dendritic branching using only a single WH2 domain.

Local actin filament formation powers the development of the signal-receiving arbor of neurons that underlies neuronal network formation. Yet, little is known about the molecules that drive these processes and may functionally connect them to the transient calcium pulses observed in restricted areas in the forming dendritic arbor. Here we demonstrate that Cordon-Bleu (Cobl)-like, an uncharacterized protein suggested to represent a very distantly related, evolutionary ancestor of the actin nucleator Cobl, despite having only a single G-actin-binding Wiskott-Aldrich syndrome protein Homology 2 (WH2) domain, massively promoted the formation of F-actin-rich membrane ruffles of COS-7 cells and of dendritic branches of neurons.

Controlling actin cytoskeletal organization and dynamics during neuronal morphogenesis.

Coordinated functions of the actin cytoskeleton and microtubules, which need to be carefully controlled in time and space, are required for the drastic alterations of neuronal morphology during neuromorphogenesis and neuronal network formation. A key process in neuronal actin dynamics is filament formation by actin nucleators, such as the Arp2/3 complex, formins and the brain-enriched, novel WH2 domain-based nucleators Spire and cordon-bleu (Cobl). We here discuss in detail the currently available data on the roles of these actin nucleators during neuromorphogenesis and highlight how their required control at the plasma membrane may be brought about.