title: Characterization of Russell bodies accumulating mutant antithrombin derived from the endoplasmic reticulum.
abstract: The endoplasmic reticulum (ER) adjusts its size and architecture to adapt to change in the surrounding environment. Russell bodies (RBs) were originally described as dilated structures of the ER cisternae containing large amounts of mutant immunoglobulin. Similar structures are observed in a wide variety of mutant proteins accumulated in the ER. We previously prepared Chinese hamster ovary (CHO) cells in which the expression of mutant antithrombin (AT) (C95R) was controlled with a Tet-On system and showed that RBs can be conditionally formed. However the precise architecture and intracellular behavior of RBs have been as yet only poorly characterized. To characterize the properties of RB, we prepared the same system using a green fluorescent protein (GFP)-fused mutant and measured the dynamics and architecture of RBs. We observed the mobile nature of the molecule in the RB lumen and RBs were separated from the rest of the ER network by narrow tubes. Furthermore, we found that the RBs were not simply expanded ER membranes. The RB lumen is filled with misfolded proteins that are surrounded by ER membranes. In addition, RBs mostly maintain their structure during cell division, possess ribosomes on their membranes and synthesize AT(C95R)-GFP. Based on the characterization of the hydrodynamic radius of AT(C95R)-GFP and the effect of DP1, an ER-shaping protein, we propose that RBs are spontaneously formed as a result of the partitioning of the misfolded AT with the shaping protein.
authors: Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama.
authors: Koji
authors: K
authors: Kimura
authors: Kosuke
authors: K
authors: Kawaguchi
authors: Yumiko
authors: Y
authors: Ueda
authors: Seisuke
authors: S
authors: Arai
authors: Masashi
authors: M
authors: Morita
authors: Tsuneo
authors: T
authors: Imanaka
authors: Ikuo
authors: I
authors: Wada
mesh_terms: D000818:Animals; D000991:Antithrombins / Q000378:metabolism*; D016466:CHO Cells; D003412:Cricetulus; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism*
chemical_list: D000991:Antithrombins; D050505:Mutant Proteins; D049452:Green Fluorescent Proteins