In contrast to planes, 3-dimensional (3D) structures like tubes are physically anisotropic. Tubular organs like our lungs and blood vessels show a striking orientation of landmarks according to the physical anisotropy of their 3D shape, in addition to planar cell polarization. However, the influence of 3D tissue topography on the constituting cells remains underexplored. We have identified a regulatory network polarizing cellular biochemistry according to the physical anisotropy of the 3D tube geometry (tube cell polarization, TCP) by a genome-wide, tissue-specific RNAi screen. During Drosophila airway remodelling, each apical cellular junction is equipotent to establish perpendicular actomyosin cables, irrespective of the longitudinal or transverse tube axis. A dynamic transverse enrichment of aPKC shifts the balance and transiently targets activated small GTPase RhoA, myosin phosphorylation and Rab11-vesicle trafficking to longitudinal junctions. We propose that the PAR complex translates tube physical anisotropy into longitudinal junctional anisotropy, where cell-cell communication aligns the contractile cytoskeleton of neighbouring cells.

The work provides a regulatory model on how 3D organ topography changes cell behaviour during organ remodelling and may be beneficial for bioengineering and in vitro organ regeneration.

 

Transient junction anisotropies orient annular cell polarization in the Drosophila airway tubes

Chie Hosono, Ryo Matsuda, Boris Adryan and Christos Samakovlis

Nature Cell Biology Nov. 9, 2015