RESEARCH
Cell Crawling Migration
​
Despite lacking a microtubule cytoskeleton, Naegleria can crawl at phenomenal speeds of up to 120 microns per minute! This is substantially faster than other amoeboid cell types like human white blood cells, which typically crawl at speeds below 30 microns per minute. We found that Naegleria amoebae crawl using actin-rich lamellar protrusions, which are nucleated by the Arp2/3 complex. This is also a mechanism used by mammalian cells, suggesting an evolutionarily ancient origin for this type of cell motility. Currently, we are investigating how these cells crawl in different environmental contexts, including confined spaces similar to those the "brain-eating amoeba" Naegleria fowleri would encounter during infection.
Relevant work: Velle and Fritz-Laylin, 2020, JCB
Osmoregulation
​
Pond-dwelling protists are constantly battling osmosis. Protists that lack a cell wall typically use a specialized organelle called a contractile vacuole to pump water out of the cell—a similar strategy to bailing water out of a leaky boat. We are investigating how Naegleria's contractile vacuole network works, and how this network responds to changes in the local environment. Because osmoregulation is critical for Naegleria's survival, and because human cells lack contractile vacuoles, understanding the cell biology underlying these organelles may reveal a much-needed drug target for N. fowleri infections.
Relevant work: Velle et al., 2023, Current Biology
Cell Division
​
Naegleria's mitotic spindles are built from divergent tubulins that assemble into a ring of microtubule bundles. While the contributions of tubulin to Naegleria's cell division have been characterized by us and others, the role of actin in this process is less clear. In many model organisms, cytokinesis—the final step of cell division—is accomplished using a contractile ring made of actin and myosin II. However, the organisms related to Naegleria lack myosin II, and use completely different mechanisms to complete division. Interestingly, Naegleria has myosin II, but if it fulfills the same functions as it would in the yeast-to-human lineage is unknown. We are therefore working to define the mechanisms of cytokinesis in Naegleria.
Relevant work: Velle et al., 2022, Current Biology
