The Refilin/Filamin complex regulates filipodia dynamics in oligodendrocyte progenitor cells.

Actin assembly and dynamics control the shape, motility and functions of diverse cell types. Programme for controlling theses dynamics is hard-coded into actin binding proteins and regulatory proteins. Refilins (RefilinA and RefilinB) are short lived regulatory proteins that interact with the actin-binding protein Filamin to convert it from an actin branching protein into one that bundles. We here show that different mechanisms converge to increase Refilin level in brain NG2+ precursor cells (polydendrocytes) committed to differentiate into the oligodendrocyte lineage. RefilinA is up-regulated through transcriptional activation during commitment into oligodendrocyte progenitor cells (OPC). RefilinB expression relies on PDGF signalling and is further stabilized by a unique auto-inhibitory domain masking the adjacent conserved PEST degradation signal. In NG2+ precursor cells and OPC, the RefilinB/Filamin complex localizes on filipodia protrusions and filipodial processes. Stable ectopic expression of Refilins in cells stimulates membrane remodelling dynamics linked with filipodia growth. These studies extend the function of the Refilin/FLNA complex to cell membrane remodelling linked with reorganization of underlying actin cytoskeleton. We performed whole transcriptomic analysis on the three cell population derived from OPC cells. Three different cultures were done and for each experiment we compared each cell population (NG2+, NG2+/A2B5 and O4) to the other 2 cell populations.