The Planar Cell Polarity: Convergent Extension Pathway
المؤلف:
T.W. Sadler
المصدر:
Langmans Medical Embryology
الجزء والصفحة:
14th E, p10-11
2025-05-21
323
The planar cell polarity (PCP) pathway regulates the process of convergent extension whereby a tissue becomes longer and narrower (Fig. 1.8A). For example, during neural tube formation (neurulation), the neural plate narrows and elongates to form the neural groove between the neural folds. Similarly, during gastrulation, cells move medially and the embryonic axis elongates. Other examples of convergent extension include elongation of the cardiac outflow tract and movement of the lateral body wall folds toward the midline. Convergent extension requires changes in cell shape together with cell movement and intercalation with other cells (Fig. 1A).
PCP refers to the reorganization of cells and cell sheets in the plane of a tissue, such as occurs during convergent extension. The principal PCP signaling pathway is the noncanonical WNT pathway, which includes the Wnt receptor Frizzled (Fz) and two other transmembrane proteins called Celsr and Vang] (Fig. 1B). These transmembrane proteins primarily target activation of DISHEVELLED (DVL), either directly or through downstream effectors, such as Prickle (Pk) and Diego (Dgo). In turn, Dvl regulates signaling via the Rho and Rac kinases to upregulate c-Iun N-terminal kinases (INK) that control cytoskeletal changes and other downstream effectors including transcription factors. Mutations in many of these genes, including FZ, CELSR, VANGL, and DVL have been shown to cause neural tube defects in mice and mutations in VANGL genes have been linked to these types of defects in humans.
Fig1. A. Drawing illustrating the process of convergent extension whereby cells intercalate with their neighbors to increase the long axis of a tissue, such as occurs during lengthening of the neural tube during neurulation. Convergent extension is dependent on the PCP pathway (the reorganization of cells and cell sheets in the plane of a tissue) that is regulated by the noncanonical WNT signaling pathway (B). Wnt binds to its receptor Frizzled, which, together with two other transmembrane proteins Celsr and Vangl, activate DISHEVELLED. Dishevelled then acts through Rho and Rac kinases to upregulate c-Jun N-terminal kinases (JNK) that control cytoskeletal changes and downstream effectors, including transcription factors.
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