Drebrin Protects Assembled Actin from INF2-FFC-mediated Severing and Stabilizes Cell Protrusions

Sudeepa Rajan; Roman Aguirre; Z Hong Zhou; Peter Hauser; Emil Reisler

doi:10.1016/j.jmb.2023.168421

Drebrin Protects Assembled Actin from INF2-FFC-mediated Severing and Stabilizes Cell Protrusions

J Mol Biol. 2024 Feb 15;436(4):168421. doi: 10.1016/j.jmb.2023.168421. Epub 2023 Dec 27.

Authors

Sudeepa Rajan¹, Roman Aguirre², Z Hong Zhou³, Peter Hauser⁴, Emil Reisler⁵

Affiliations

¹ Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
² Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA; Department of Microbiology, Immunology and Molecular Genetics, UCLA, Los Angeles, CA 90095, USA.
³ Department of Microbiology, Immunology and Molecular Genetics, UCLA, Los Angeles, CA 90095, USA.
⁴ Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA 91344, USA; Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA.
⁵ Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA; Molecular Biology Institute, UCLA, Los Angeles, CA 90095, USA. Electronic address: reisler@mbi.ucla.edu.

PMID: 38158176
DOI: 10.1016/j.jmb.2023.168421

Abstract

Highly specialized cells, such as neurons and podocytes, have arborized morphologies that serve their specific functions. Actin cytoskeleton and its associated proteins are responsible for the distinctive shapes of cells. The mechanism of their cytoskeleton regulation - contributing to cell shape maintenance - is yet to be fully clarified. Inverted formin 2 (INF2), one of the modulators of the cytoskeleton, is an atypical formin that can both polymerize and depolymerize actin filaments depending on its molar ratio to actin. Prior work has established that INF2 binds to the sides of actin filaments and severs them. Drebrin is another actin-binding protein that also binds filaments laterally and stabilizes them, but the interplay between drebrin and INF2 on actin filament stabilization is not well understood. Here, we have used biochemical assays, electron microscopy, and total internal reflection fluorescence microscopy imaging to show that drebrin protects actin filaments from severing by INF2 without inhibiting its polymerization activity. Notably, truncated drebrin - DrbA1-300 - is sufficient for this protection, though not as effective as the full-length protein. INF2 and drebrin are abundantly expressed in highly specialized cells and are crucial for the temporal regulation of their actin cytoskeleton, consistent with their involvement in peripheral neuropathy.

Keywords: TIRFM; actin severing; cell shape; cytoskeleton; neurons.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Actin Cytoskeleton / chemistry
Actins* / chemistry
Cell Surface Extensions / chemistry
Formins* / chemistry
Microscopy, Electron
Neurons / metabolism
Neuropeptides* / chemistry

Substances

Actins
drebrins
Formins
Neuropeptides
INF2 protein, human

Grants and funding

R01 GM077190/GM/NIGMS NIH HHS/United States