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November 29, 2018 | 11:00 a.m. - 12:00 p.m.
Category: Seminar
Location: Scott Hall #3125 | Map
540 E. Canfield
Detroit, MI 48201
Cost: Free
Audience: Current Graduate Students, Faculty

Anna Sundborger, PhD

Assistant Professor and Section Leader of Cryo-EM and Molecular Cell Biology, University of Minnesota Hormel Institute

“Mitochondrial membrane remodeling at the brink of death”

ABSTRACT

Mitochondria are highly dynamic organelles constantly undergoing fission and fusion events. Dysregulation of mitochondrial dynamics is associated with changes in organelle function, transport, location, and quality control (1). As such, regulators of mitochondria dynamics are critical for cell health. Membrane remodeling Bin/Amphiphysin/Rvs (BAR) protein endophilin B1 has been implicated in mitochondrial dynamics, although the underlying mechanisms are poorly understood. BAR proteins mediate remodeling of cellular membranes by inducing varying degrees of membrane curvature, a property that is promoted by protein dimerization and assembly of crescent-shaped BAR domains that enforce their shapes onto membranes (2-5). Knockdown of endophilin B1 leads to dysregulation of mitochondrial dynamics and inhibition of apoptosis (6-10), suggesting that endophilin B1-mediated membrane remodeling coordinates mitochondrial dynamics with critical cell death processes. Using cryo-electron microscopy to reconstruct endophilin B1 assembled on mitochondria outer membranes (MOM), we find that endophilin B1 assembles into tetramers that further organize into small assemblies or helical scaffolds. Furthermore, endophilin B1 promotes recruitment of Bax to MOM-like membranes, promotes Bax-mediated membrane permeabilization, and interacts with dynamin family members responsible for MOM fission, IRGM and Drp1. Based on these findings, we propose that endophilin B1 is critical for mitochondrial dynamics and Bax-mediated apoptosis due to its unique ability to remodel mitochondrial outer membranes, which controls recruitment and organization of effector proteins, Bax and dynamin family members, and leads to activation of down-stream membrane remodeling events.

For more information about this event, please contact Suzanne Shaw at 577-5325 or sshaw@wayne.edu.