Borg5/Cdc42EP curbs Septin dependent stress fiber formation by antagonizing alpha Actinin 4 and Myosin IIA
Ontology highlight
ABSTRACT: The Borg5/Cdc42EP family comprises septin binding proteins, which are known to participate in septin-dependent stress fiber formation. We show here that epithelial Borg5/Cdc42Ep1 restrains stress fibers instead. Borg5 decorates septin filament-aligned thin F-actin filaments under the nucleus of MDCK cells, which in Borg5 depleted cells are replaced by thick stellate stress fibers. These associate with either cell-substratum- or cell-cell- adhesions, increasing tension on E-cadherin based junctions and causing MDCK cells to undergo collective streaming. We identified two known septin partners, Myosin-IIA and alpha Actinin 4 (ACTN4), among proteins that co isolated with Borg5 from MDCK lysates. We found that Borg5 binds Myosin-IIA and ACTN4 directly and negatively regulates their F-actin association. Since both septin partners along with Septins 2 and 9 were furthermore required for the Borg5 depletion-induced F actin phenotype, we propose that Borg5 prevents stellate stress fiber formation by counteracting septin dependent ACTN4 and Myosin IIA activities. The mass spectrometry raw files and search results for Borg 5 affinity purifications are deposited here.
INSTRUMENT(S): Orbitrap Eclipse
ORGANISM(S): Canis Lupus Familiaris (ncbitaxon:9615)
SUBMITTER: Beatrix Ueberheide
PROVIDER: MSV000092958 | MassIVE |
SECONDARY ACCESSION(S): PXD045675
REPOSITORIES: MassIVE
ACCESS DATA