The Department of Estuarine and Ocean Science will be hosting Katrina Velle, Assistant Professor in the Biology Department at UMass-Dartmouth on February 19! Dr. Velle will be discussing “The actin cytoskeleton drives cell migration in a model of the “brain-eating amoeba”. This seminar will take place from 12:30-1:30 in SMAST East 101-103 and on Zoom.

Abstract:

The “brain eating amoeba” Naegleria fowleri has a ~95% case fatality rate, and primarily infects children. Despite its clear importance, we have little understanding of the basic cell biological mechanisms that underlie Naegleria’s pathogenesis, which is key information for the identification of new drug targets. What is clear, however, is that actin assembly and disassembly drives many cellular processes in Naegleria. The Velle lab studies how the actin cytoskeleton promotes cell migration, cell division, and osmoregulation—three phenotypes important for establishing and spreading infection. This talk will specifically focus on cell migration. To initiate an infection, Naegleria amoebae must crawl through narrow channels in the skull to reach the brain. To study this process, we expose Naegleria gruberi (a nonpathogenic model system) to different types of confinement including microchannels. Using quantitative microscopy, we show that Naegleria amoebae seek out confinement; after contacting the entrance to a microchannel, cells continue to probe the surface until they get inside. Once cells fully enter these channels, they crawl extremely quickly (up to 100 microns/min) in one direction for millimeters. While migrating in confined environments, cells show hallmarks of “blebbing” motility, in which the plasma membrane detaches from the underlying actin cortex and blisters outward, creating an actin-free protrusion. This is in contrast to unconfined cells, which typically use actin-filled protrusions to crawl. Collectively, these data suggest that once Naegleria amoebae detect an opening to a narrow channel—similar to what they encounter during infection—cells will switch to blebbing motility to crawl quickly and persistently.