A Molecular Tension Sensor for N-Cadherin Reveals Distinct Forms of Mechanosensitive Adhesion Assembly in Adherens and Synaptic Junctions

Abstract

N-cadherin mediates physical linkages in a variety of force-generating and load-bearing tissues.To enable visualization and quantification of mechanical loads experienced by N-Cadherin, we developed a genetically-encoded FRET-based tension sensor for this protein. We observe that N-Cadherin supports non-muscle myosin II (NMII) activity-dependent loads within the adherens junctions (AJs) of VSMCs and the synaptic junctions (SJs) of neurons. To probe the relationship between mechanical loads and AJ/SJ formation, we evaluated the relationships between Ncadherin tension and the size of these adhesion structures. In VSMCs, no relationship between N-cadherin tension and AJ size was observed, consistent with previously observed homeostatic regulation of mechanical loading. In neurons, a strong correlation between SJ size and N-cadherin load was observed, demonstrating an absence of homeostatic regulation. Treatment with glycine, a known initiator of synapse maturation, lead to increased SJ size and N-cadherin load, suggesting a role for mechanosensitive signaling in this process. Correspondingly, we observe that NMII activity is required for the Src-mediated phosphorylation of NMDAR subunit GluN2B at Tyr 1252, which is a key event in synaptic potentiation. Together these data demonstrate Ncadherin tension is subject to cell type specific regulation and that mechanosensitive signaling occurs within SJs.

Förster resonance energy transfer efficiency of the vinculin tension sensor in cultured primary cortical neuronal growth cones

“…23 In results reported in a manuscript posted to BioRxiv, a Förster resonance energy transfer (FRET)-based sensor was also developed to measure tension across N-cadherin at synaptic junctions. 24 …”