Lipid Research Division Seminar Series

Architecture of a bridge-like lipid transfer protein
Sarah Clark, Oregon State University

Cells and cellular organelles are surrounded by membranes that constantly undergo lipid modification during processes such as cell growth, organelle biogenesis, exocytosis, and phagocytosis. Bridge-like lipid transport proteins (BLTPs) have emerged as key players due to their role in lipid transport. BLTPs localize to membrane contact sites, where they form hydrophobic tunnels proposed to function as “lipid superhighways” that mediate bulk lipid transfer between membranes. Despite their importance, the mechanism of lipid transfer remains unclear. Here, we present the subunit composition and cryo-electron microscopy structure of the native LPD-3 BLTP complex from transgenic C. elegans, providing a foundation for mechanistic studies.

"Tweek-ing" lipid transfer at ER-PM contact sites to drive glial phagocytosis
Yunsik Kang, University of Colorado School of Medicine

Bridge-like lipid transfer proteins are proposed to support membrane expansion at organelle contact sites, but how they function during rapid cellular remodeling in vivo remains unclear. During Drosophila metamorphosis, astrocytes transform into highly phagocytic cells that clear large amounts of neuronal debris generated by synaptic and axonal remodeling. We found that the conserved bridge-like lipid transfer protein Tweek/BLTP1 is upregulated in phagocytic astrocytes and is essential for membrane dynamics required for debris internalization. These findings reveal a physiological requirement for non-vesicular lipid transport during neural development and will interest researchers in glial biology, membrane trafficking, and lipid homeostasis.