One of the most interesting, but poorly understood, aspects of cell migration is the contribution of blebbing. Membrane blebs are protrusions in which the membrane is forced outwards by the internal hydrostatic pressure of the cell, ripping it away from the cortical cytoskeleton and causing a bulbous projection. The force for this is generated by myosin II contraction (in the same way that squeezing a partially inflated balloon causes an unrestrained region to bulge out), but it is unclear whether the position in which the bleb forms is determined either by local disruption of cortical actin or by localized build-up of pressure. Blebbing is a well-documented phenomenon that occurs in a wide range of cell types, but has recently gained interest following the observation that cancer cells are able to switch between motility driven by actin polymerization at the leading edge, and blebbing-driven motility, to invade into 3D matrices. It has become common in the field to refer to the former as ‘mesenchymal’ motility, and the bleb-based mechanism as ‘amoeboid’, presumably referring to the hydrostatically driven flow of cytoplasm seen in giant amoebas like Chaos chaos.
This nomenclature is unfortunate and ambiguous. Amoebae like Dictyostelium move using actin-based processes as well as blebs, with the ‘mesenchymal’ form predominating in most experiments. Worse, haematopoietic cells such as neutrophils and macrophages are described as ‘amoeboid’ because they have no clearly defined rostrocaudal or dorsoventral axes, unlike for example epithelial cells. However, the amoeboid migration of these cells typically uses a ‘mesenchymal’ actin-based mechanism.
It is known that cancer cells don’t live on glass slides, yet the vast majority of images related to cancer biology come from the cells being photographed on flat, two-dimensional surfaces; images that are sometimes used to make conclusions about the behaviour of cells that normally reside in a more complex environment. Now, researchers at University of Texas Southwestern have developed a new…
I was thinking about fanfic writer appreciation day on and off all day, and man, where even to begin? I want to give all my love to basically everyone in the rumbelle fanfic community on tumblr. I’d never participated in a fic-writing community before ouat, and I doubt I’ll ever see one as supportive and loving and good-natured. You are all wonderful people and phenomenal writers and the show is lucky to have you. I’m lucky to know you.