Abstract
Membrane-shaping proteins are driving forces behind establishment of proper cell morphology and function. Yet, their reported structural and in vitro properties are noticeably inconsistent with many physiological membrane topology requirements. We demonstrate that dendritic arborization of neurons is powered by physically coordinated shaping mechanisms elicited by members of two distinct classes of membrane shapers: the F-BAR protein syndapin I and the N-Ank superfamily protein ankycorbin. Strikingly, membrane-tubulating activities by syndapin I, which would be detrimental during dendritic branching, were suppressed by ankycorbin. Ankycorbin's integration into syndapin I-decorated membrane surfaces instead promoted curvatures and topologies reflecting those observed physiologically. In line with the functional importance of this mechanism, ankycorbin- and syndapin I-mediated functions in dendritic arborization mutually depend on each other and on a surprisingly specific interface mediating complex formation of the two membrane shapers. These striking results uncovered cooperative and interdependent functions of members of two fundamentally different membrane shaper superfamilies as a previously unknown, pivotal principle in neuronal shape development.