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Biol Open. 2016 Oct 15;5(10):1351-1361. doi: 10.1242/bio.019588.

Refilins are short-lived Actin-bundling proteins that regulate lamellipodium protrusion dynamics.

Author information

1
INSERM U873 and INSERM Unité 1038, Grenoble F-38000, France CEA, BIG, BGE, Grenoble F-38000, France Université Grenoble Alpes, Grenoble F-38000, France.
2
INSERM U873 and INSERM Unité 1038, Grenoble F-38000, France Université Grenoble Alpes, Grenoble F-38000, France.
3
Genomic and Microgenomic Platform, ProfileXpert, Bron F-69676, France Lyon Neuroscience Research Center INSERM U1028/CNRS UMR 5292, Lyon F-69372, France.
4
INSERM U873 and INSERM Unité 1038, Grenoble F-38000, France CEA, BIG, BGE, Grenoble F-38000, France Université Grenoble Alpes, Grenoble F-38000, France jacques.baudier@univ-amu.fr.

Abstract

Refilins (RefilinA and RefilinB) are members of a novel family of Filamin binding proteins that function as molecular switches to conformationally alter the Actin filament network into bundles. We show here that Refilins are extremely labile proteins. An N-terminal PEST/DSG(X)2-4S motif mediates ubiquitin-independent rapid degradation. A second degradation signal is localized within the C-terminus. Only RefilinB is protected from rapid degradation by an auto-inhibitory domain that masks the PEST/DSG(X)2-4S motif. Dual regulation of RefilinA and RefilinB stability was confirmed in rat brain NG2 precursor cells (polydendrocyte). Using loss- and gain-of-function approaches we show that in these cells, and in U373MG cells, Refilins contribute to the dynamics of lamellipodium protrusion by catalysing Actin bundle formation within the lamella Actin network. These studies extend the Actin bundling function of the Refilin-Filamin complex to dynamic regulation of cell membrane remodelling.

KEYWORDS:

FAM101A; FAM101B; FilaminA; Polydendrocyte; RefilinA; RefilinB

Conflict of interest statement

The authors declare no competing or financial interests.

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