Camryn Slosky '22

Different rates of receptor recycling and breakdown influence asymmetric cell division

Multicellular organisms are made up of a variety of different types of cells that perform different functions. Even something seemingly as simple as the marine invertebrate Ciona robusta, more commonly known as the sea squirt, has muscle cells, immune cells, and heart cells, to name a few. Incredibly, all of these cell types come from a single fertilized cell called a zygote. How is this possible? In sea squirts, cells known as founder cells re-distribute proteins called FGF receptors during cell division so that only half of the daughter cells have FGF receptors. The cells that contain FGF receptors go on to form heart cells, while the other half form muscle cells. During division, receptors are pulled away from the cell surface and held inside the cell, where they are either broken down or recycled back to the surface. In my research, I investigated how receptor breakdown contributes to receptor redistribution during cell division by observing the location of FGF receptors that were unable to degrade during division. Surprisingly, the removal of receptor breakdown changed FGF receptor location early, but not late, in cell division. This finding suggests that receptor breakdown plays a role in promoting unequal distribution early in division, while receptor recycling promotes unequal distribution later in division.