The Rap1 GTPase performs two separable functions during cellularization to enable ventral furrow formation
Morphogenetic processes involve dynamic cell-level events, such as contractility, shape changes, and adhesion between cells and extracellular structures. These cell-level changes require intercellular coordination in order to generate the appropriate tissue-level output. Although the repertoire of these cell-level changes is limited, these processes are reused serially during development to…
Morphogenetic processes in cells necessitate intercellular coordination for proper tissue development. Rap1, a small GTPase, plays a crucial role in ventral furrow formation during cellularization in the early Drosophila embryo. Researchers have developed a biosensor and optogenetic tools to study Rap1's function in this process.
Using these tools, scientists observed that Rap1 activity declines in ventral cells as the furrow forms. Optogenetic experiments revealed that acute inhibition of Rap1 during furrowing has minimal impact. However, Rap1 contributes to furrowing through two distinct functions during an earlier stage called cellularization.
Firstly, Rap1 is continuously required for efficient membrane ingression throughout the cellularization process. Secondly, Rap1 is transiently needed to initiate adherens junctions, which later coordinate contractility across the ventral epithelium. Understanding how these molecular-level events orchestrate tissue-level transformations provides valuable insights into cellularization mechanisms.
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