3D Endosomal Ultrastructure in Cells Expressing NPC

Office Of The Director, Nih

Investigators

Abstract

To complement studies being conducted by NIDDK investigators to understand defects in the endocytic trafficking pathway that occur in Niemann-Pick Type C Disease (NPC), we are determining the cellular ultrastructure of endosomal vesicles and endosomal tubules in cultured fibroblasts and chinese hamster ovary (CHO) cells containing wild-type or mutant NPC protein. Cells sectioned to a thickness of 200 to 400 nanometers were analyzed by automated electron tomography in an energy-filtering 300 kV field-emission transmission electron microscope. Double-axis tilt series were collected over an angular range of +/- 70 degrees and three-dimensional volumes reconstructed by weighted back-projection. The reconstructions show multi-lamellar tubules that appear to correlate with late endosomal tubules previously observed in fluorescent light microscopy of labeled cells.