About tricellular junctions
bsky.app/profile/epim...

About pulsatile actomyosin
bsky.app/profile/epim...

For more such threads, follow @epimechfc.bsky.social:
epithelialmechanics.github.io

Thank you for reading!

The examples mentioned are work by the labs of J Zallen (MSK Cancer Center), S Tsukita (Kyoto U), A Miller (U Michigan), @luschnig.bsky.social @ybellaichelab.bsky.social @bedzhovlab.bsky.social @nicolettapetridou.bsky.social , and S Bogdan (U Münster).

11/ From local tension sensors to organizers of global architecture, TCJs bridge cell mechanics with tissue-wide processes. Uncovering how they integrate biochemical and mechanical cues will help us understand their role in polarizing and shaping tissues in development & disease.

10/ TCJs not only affect signaling via diffusion modulation, but can also act as signaling hubs, e.g. regulating the localization of PCP and Hippo pathway components. This can e.g. lead to polarized protrusions needed for tissue shaping. doi.org/10.1083/jcb....

9/ This TCJ-material state interdependence can impact signaling.

In the zebrafish embryo, tissue solidification leads to TCJ formation & concomitant tissue porosity reduction. This restricts morphogen diffusion & limits the mesendoderm specification region. doi.org/10.1101/2025...

8/ Indeed, adhesion-dependent fluid-to-solid material phase transitions go hand-in-hand with TCJ formation. This promotes an epithelial organization of the tissue, and even the establishment of apical polarity. doi.org/10.1101/2025...

7/ Beyond regulating mechanosensitivity, TCJs help orchestrate epithelial identity.

In the mouse epiblast, TCJ formation marks the transition from apolar to epithelial tissue-scale organization. Establishing TCJs is essential for epithelial polarity!
doi.org/10.1016/j.de...

6/ Similarly, TCJs scale cell mechanosensitivity with area: TCJ number & distribution control stress fiber dynamics. This TCJ-aSF interplay drives area-dependent mechanical responses, regulating tissue elongation & proliferation under anisotropic stress. doi.org/10.1126/scie...

5/ Beyond permeability, TCJs can function as sensors of cell shape and tissue mechanical stress orientation, even acting as spatial “landmarks” to orient mitosis by regulating microtubule pulling forces. doi.org/10.1038/natu...

4/ But TCJs don’t just seal tissues - sometimes they must open.

During Drosophila oogenesis, transient TCJ opening allows paracellular transport of proteins into the oocyte. This is driven by local loss of adhesion & reduced actomyosin contractility.
doi.org/10.1016/j.de...

3/ TCJs are mechanosensitive “tension hotspots”: their molecular composition and interactions change in response to forces. This adaptability is required to maintain epithelial integrity. If impaired, junctions leak and barrier function is disrupted. doi.org/10.1016/j.cu...

2/ The connection at TCJs is mediated by specialized proteins, most notably Tricellulins and Angulins in vertebrates and Gliotactin and Anakonda in invertebrates.

Importantly, TCJs are connected to the actin cytoskeleton, and bear the tensions of 3 BCJs!
doi.org/10.1091/mbc....