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J Cell Sci. 2017 May 15;130(10):1730-1739. doi: 10.1242/jcs.195099. Epub 2017 Mar 27.

Non-canonical activity of the podosomal formin FMNL1γ supports immune cell migration.

Author information

1
Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210, USA.
2
Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210, USA blystons@upstate.edu.

Abstract

Having previously located the formin FMNL1 in macrophage podosomes, we developed an in vivo model to assess the role of FMNL1 in the migration activities of primary macrophages. Deletion of FMNL1 in mice was genetically lethal; however, targeted deletion in macrophages was achieved by employing macrophage-specific Cre. Unchallenged FMNL1-deficient mice exhibited an unexpected reduction in tissue-resident macrophages despite normal blood monocyte numbers. Upon immune stimulus, the absence of FMNL1 resulted in reduced macrophage recruitment in vivo, decreased migration in two-dimensional in vitro culture and a decrease in the number of macrophages exhibiting podosomes. Of the three described isoforms of FMNL1 - α, β and γ - only FMNL1γ rescued macrophage migration when expressed exogenously in depleted macrophages. Surprisingly, mutation of residues in the FH2 domain of FMNL1γ that disrupt barbed-end actin binding did not limit rescue of macrophage migration and podosome numbers. These observations suggest that FMNL1 contributes to macrophage migration activity by stabilizing the lifespan of podosomes without interaction of fast-growing actin termini.

KEYWORDS:

Actin; Formin; Macrophage; Motility; Podosome

PMID:
28348104
PMCID:
PMC5450187
DOI:
10.1242/jcs.195099
[Indexed for MEDLINE]
Free PMC Article

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