Multicellular Organization Laboratory
During development of various tissues, a group of cells are polarized in the same orientation and behave coordinately. (For example, convergent extension during gastrulation and hair cells of the organ of Corti in inner ear)
Regulation of cell polarity
Such coordinate cell polarization is often controlled by the Wnt/PCP pathway which share asymmetric localization of Disheveled with the Wnt/β-catenin asymmetry pathway. Although the PCP pathway is a Wnt pathway, roles of Wnt proteins are obscure. Furthermore, it is not known how the orientation of polarities are determined in these processes.
Most dividing cells in C. elegans are polarized in the same orientation, because β-catenin is always localizes to the posterior daughter nuclei.
For example, epithelial stem cells called seam cells on the lateral side of the animals are coordinately polarized along the anterior-posterior axis, and divide asymmetrically to produce the anterior daughters that fuse with other epithelial cells and the posterior daughters that remain to be the stem cells.
We have recently found that orientations of polarities of the epithelial stem cells are redundantly regulated by four Wnt proteins that are expressed either anterior or posterior regions.
Therefore, the stem cells can be properly polarized by Wnts expressed either anterior or posterior sides of the cells. They can also properly respond to the Wnts expressed quite far from the cells. We will elucidate how cells can recognize different Wnts and direction in which Wnts are coming.
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