47. Activation of the Wnt signal transduction pathway is extremely important during early development. Of the various pathways, which one of the following is most

likely to induce cytoskeletal changes, like cell shape and movement?

Activation of the non-canonical Wnt/Planar Cell Polarity (PCP) pathway is most likely to induce cytoskeletal changes like cell shape and movement during early development. This pathway operates independently of the β-catenin canonical pathway and instead activates small Rho family GTPases such as RhoA, Rac1, and Cdc42, which are key regulators of actin cytoskeleton remodeling. Upon Wnt ligand binding (e.g., Wnt5a or Wnt11) to Frizzled receptors and co-receptors such as ROR2, downstream effectors—including Dishevelled (DVL)—activate RhoA which leads to actin cytoskeletal reorganization through Rho-associated kinase (ROCK). This enables changes in cell polarity, motility, and morphology essential for developmental processes like gastrulation and tissue morphogenesis.

Additionally, the Wnt/Ca2+ pathway also contributes to cytoskeletal regulation by increasing intracellular calcium levels, which activate signaling molecules such as protein kinase C and CaMKII, modulating cell adhesion and migration. However, the PCP pathway is the primary non-canonical route linked explicitly to cytoskeletal rearrangements and cellular movement.

This understanding highlights the integral role of non-canonical Wnt signaling, especially the PCP pathway, in regulating cell shape and movement through cytoskeleton modulation during early development stages.

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