Skip to Content
Merck

Focal adhesions contain three specialized actin nanoscale layers.

Nature communications (2024-03-22)
Reena Kumari, Katharina Ven, Megan Chastney, Shrikant B Kokate, Johan Peränen, Jesse Aaron, Konstantin Kogan, Leonardo Almeida-Souza, Elena Kremneva, Renaud Poincloux, Teng-Leong Chew, Peter W Gunning, Johanna Ivaska, Pekka Lappalainen
ABSTRACT

Focal adhesions (FAs) connect inner workings of cell to the extracellular matrix to control cell adhesion, migration and mechanosensing. Previous studies demonstrated that FAs contain three vertical layers, which connect extracellular matrix to the cytoskeleton. By using super-resolution iPALM microscopy, we identify two additional nanoscale layers within FAs, specified by actin filaments bound to tropomyosin isoforms Tpm1.6 and Tpm3.2. The Tpm1.6-actin filaments, beneath the previously identified α-actinin cross-linked actin filaments, appear critical for adhesion maturation and controlled cell motility, whereas the adjacent Tpm3.2-actin filament layer beneath seems to facilitate adhesion disassembly. Mechanistically, Tpm3.2 stabilizes ACF-7/MACF1 and KANK-family proteins at adhesions, and hence targets microtubule plus-ends to FAs to catalyse their disassembly. Tpm3.2 depletion leads to disorganized microtubule network, abnormally stable FAs, and defects in tail retraction during migration. Thus, FAs are composed of distinct actin filament layers, and each may have specific roles in coupling adhesions to the cytoskeleton, or in controlling adhesion dynamics.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-GAPDH antibody produced in rabbit, ~1 mg/mL, affinity isolated antibody, buffered aqueous solution
Sigma-Aldrich
Anti-ERC1 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution, Ab1
Sigma-Aldrich
Monoclonal Anti-Vinculin antibody produced in mouse, clone hVIN-1, ascites fluid
Sigma-Aldrich
HEPES, ≥99.5% (titration)
Sigma-Aldrich
Monoclonal Anti-Tropomyosin antibody produced in mouse, clone TM311, ascites fluid
Sigma-Aldrich
HEPES solution, 1 M, pH 7.0-7.6, sterile-filtered, BioReagent, suitable for cell culture
Sigma-Aldrich
Monoclonal Anti-Talin antibody produced in mouse, clone 8d4, ascites fluid
Sigma-Aldrich
Anti-KANK2 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution
Sigma-Aldrich
Anti-Kindlin-2 Antibody, clone 3A3, clone 3A3, from mouse