Junctional β-Catenin Stabilization Links Wnt Signaling and Force Generation

β-catenin plays two fundamental roles in animal tissues: it acts as a transcriptional effector of canonical Wnt signaling and as a core structural component of adherens junctions that mediate cell–cell adhesion. In canonical Wnt signaling, the post-transcriptional regulation of β-catenin abundance, primarily through regulated phosphorylation, ubiquitination, and proteasomal degradation, determines whether the pathway is “off” or “on.” Despite the central importance of β-catenin stabilization, in vivo measurements of β-catenin protein lifetime and stabilization dynamics during development remain limited. Here, we measure the stability of endogenous β-catenin in vivo using tandem fluorescent protein timers (tFPs; “Timers”) inserted as minimally disruptive cassettes within the endogenous locus. Timers allow simultaneous visualization of a newly synthesized, rapidly accumulating pool (fast-maturing GFP) and a long-lived, stabilized pool (slow-maturing RFP). Surprisingly, the strongest stabilization does not occur in canonical Wnt patterning stripes; instead, we observe marked stabilization of junctional β-catenin at the leading edge during dorsal closure, a force-generating morphogenetic process. This stabilization is not explained by canonical Wnt ligand input and seems to reflect a stability program linked to β-catenin’s adhesive function in adherens junctions. We suggest that a stable junctional pool of β-catenin is vital for dorsal closure mechanics and provide evidence that this stabilization is regulated by Dishevelled and JNK, thus connecting Wnt pathway components to mechanotransduction.