Cell Shape Determination: A Pivotal Role for Rho

摘要

Morphogenesis, the complex process that shapes cells to their myriad forms, has long fascinated biologists. Two reports in this issue (1, 2) move us closer to an understanding of why one particular cell--a yeast cell--has its characteristic shape. Cells of the yeast Saccharamyces cerevisiae bud to form daughters in their own image. Once a mother cell commits to undergo a new mitotic cycle, a bud site is chosen through an elaborately regulated biochemical hierarchy (3). With a site chosen, cellular polarity is established and the bud emerges and grows, receiving a full complement of cellular components; after cytokinesis, the bud forms a daughter cell. It is during bud construction that the distinctive yeast cell shape is established by the architecture of cell wall glucan deposition. Construction of the bud begins at the bud tip, and many components need to be marshalled at this site to ensure their ordered elaboration: The actin cytoskeleton polarizes the secretory apparatus to the bud tip to provide the necessary building materials for cell wall assembly.