Elucidating the Mechanisms of Microtubule Regulation at the Cellular Cortex

University Of California, San Diego, La Jolla CA

Investigators

Abstract

Project Summary: Microtubule (MT) dysfunction is linked to various developmental and neurological disorders. While significant advances have been made in understanding MT dynamics in the cytoplasm, their regulation at cellular membranes remains poorly understood. The primary objective of this proposal is to investigate how MT dynamics is regulated at the interface of the plasma membrane and the cytoskeleton, known as the cortex. My recent postdoctoral research suggests that phase separation-dependent condensation, a process of protein de-mixing, may serve as a cellular mechanism to compartmentalize cortical MT regulators, such as EFA-6, and modulate MT dynamics locally. The proposed study aims to uncover the mechanisms governing EFA-6 phase separation at the cortex and its effect on EFA-6's MT regulatory activity. This study will identify novel factors that regulate MT dynamics at the cortex, elucidate their mechanisms of action, and characterize their roles in MT-membrane interactions dependent cellular functions. Unraveling the MTs regulations at this interface will offer new insights into the fundamentals of MT homeostasis and could inform the treatment of diseases associated with MT dysfunction, such as microcephaly, amyotrophic lateral sclerosis, and Parkinson’s disease. C. elegans will be used as the model organism due to its well-characterized MT dynamics, genetic tractability, and transparency for live-cell imaging. The project will focus on two specific aims: 1) Investigating the mechanisms by which EFA-6 undergoes phase separation and modulates MT dynamics, using proximity labeling, in vitro assays, and genetic analyses (K99 phase). 2) Identifying and characterizing novel cortical MT regulators and investigating their roles in regulating membrane functions through genetic, microscopic, and biochemical approaches (R00 phase). This proposal will deepen our understanding of how cells regulate MT dynamics at the cortex to achieve specific membrane morphologies and functions. Furthermore, this study will uncover novel regulators of MTs, shedding light on MT homeostasis under both normal and stress conditions. Overall, the proposed research will broaden our knowledge of MT dynamics and organization and provide insights into management or treatment of MT dysfunction associated diseases. The mentored phase will be conducted at UC San Diego under the guidance of Professors Yishi Jin and Andrew Chisholm, renowned experts in genetics and neurobiology. UCSD and neuroscience faculties provide an excellent environment for the proposed research. I will receive hands-on training in in vitro phase separation and in vitro MT analysis from Prof. Lizhen Chen and Prof. Arshad Desai, respectively. Mentorship from additional experts, including Professors Nicholas Spitzer and Sreekanth Chalasani, will help me transition to an independent research career. Altogether, this research will deepen our understanding of how cells regulate MT dynamics at the cortex, advancing knowledge of cellular morphogenesis and membrane functions, which are critical for understanding and treating diseases such as Alzheimer’s, microcephaly, and ALS.