Karen Juanez / Biology / Faculty Mentor: Piya Ghose
Cell elimination is a key feature of both development and homeostasis, as well as pathological states. Specialized cells, such as neurons, are defined by elaborate processes bearing different compartments with vastly distinct subcellular architectures. Morphologically complex cells can undergo regressive events, such as region-specific pruning in neurons. However, the molecular mechanisms behind specialized cell regression remains to be fully understood. We addressed this in the powerful model organism C. elegans by studying a novel embryonic cell death program we previously characterized, Compartmentalized Cell Elimination (CCE). We have observed that CCE occurs in a stereotyped fashion in two sets of polarized cells, an epithelial cell and a set of sex-specific sensory neurons. In these cells, we observe two distinct elimination morphologies in the single process/neurite: proximal beading followed by fragmentation, and distal thickening and shortening (retraction). Here we report that CCE involves highly ordered and organized microtubule (MT) dynamics across each process compartment that are disrupted when endoplasmic reticulum (ER) network stability is compromised. We also find stereotyped, and restricted, spatiotemporal ER dynamics. Interestingly, a MT-severing protein is distributed both proximally and distally, suggesting ER-associated and ER-independent dual roles in CCE.
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