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Reticular adhesions are assembled at flat clathrin lattices and opposed by active integrin α5β1
Laura Hakanpää1,2,3, Amr Abouelezz1,2,3, An-Sofie Lenaerts1,2,3
1Helsinki Institute of Life Science, University of Helsinki , Helsinki, Finland.
The Journal of Cell Biology
|May 26, 2023
Summary
Reticular adhesions (RAs) assemble at flat clathrin lattices (FCLs), challenging the view that endocytosis only disassembles cell adhesions. This novel mechanism involves fibronectin and integrin signaling, impacting cell migration.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- Reticular adhesions (RAs) contain integrin αvβ5 and flat clathrin lattices (FCLs).
- FCLs share molecular components with clathrin-mediated endocytosis (CME) carriers, but the colocalization of FCLs and RAs is unexplained.
- The conventional understanding is that endocytosis disassembles cellular adhesions.
Purpose of the Study:
- To elucidate the mechanism of reticular adhesion assembly.
- To investigate the relationship between FCLs, CME, and RA formation.
- To explore the role of fibronectin and its receptors in RA assembly and cell migration.
Main Methods:
- Cell culture on fibronectin (FN)-rich matrices.
- Inhibition of clathrin-mediated endocytosis (CME) machinery.
- Live-cell imaging to observe RA establishment and FCL coassembly.
- Analysis of integrin α5β1 activation at Tensin1-positive fibrillar adhesions.
Main Results:
- Reticular adhesions (RAs) assemble at flat clathrin lattices (FCLs).
- Fibronectin (FN) and integrin α5β1 control RA assembly.
- Inhibition of CME machinery abolished RAs, indicating FCL coassembly is required for RA establishment.
- FN's inhibitory activity on RAs is mediated by integrin α5β1 activation at fibrillar adhesions.
- A novel mechanism shows endocytic proteins actively assembling cell adhesions.
Conclusions:
- Endocytic proteins, specifically components of FCLs, actively participate in the assembly of cell adhesions like RAs.
- This novel adhesion assembly mechanism is linked to cell migration through crosstalk with cell-matrix adhesions.
- The findings challenge the traditional view of endocytosis solely as a disassembly process for cellular adhesions.
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