Mutant SOD1 forms ion channel: Implications for ALS pathophysiology

NEUROBIOLOGY OF DISEASE

卷:45

Article

Allen, Michael J.^2,3  Lacroix, Jerome J.⁴  Ramachandran, Srinivasan⁵  Capone, Ricardo⁵  Whitlock, Jenny L.^2,3  Ghadge, Ghanashyam D.¹  Arnsdorf, Morton F.⁶  Roos, Raymond P.¹  Lal, Ratnesh⁵ 

[1] Univ Chicago, Dept Neurol, Chicago, IL 60637 USA

[2] Univ Chicago, Dept Med, Ctr Nanomed, Chicago, IL 60637 USA

[3] Univ Chicago, Dept Med, Sect Pulm Crit Care, Chicago, IL 60637 USA

[4] Univ Chicago, Dept Biochem & Mol Biol, Chicago, IL 60637 USA

[5] Univ Calif San Diego, Dept Mech & Aerosp Engn, Dept Bioengn, La Jolla, CA 92093 USA

[6] Univ Chicago, Dept Med, Cardiol Sect, Chicago, IL 60637 USA

关键词: Amyotrophic lateral sclerosis;    Superoxide dismutase;    A4V;    Protein misfolding;    Atomic force microscopy;    Fluo-4 calcium assay;    DiBAC(4)(3) membrane potential measurement;   

DOI  :  10.1016/j.nbd.2011.08.031

来源: Elsevier

【 摘 要 】

Point mutations in the gene encoding copper-zinc superoxide dismutase (SOD1) impart a gain-of-function to this protein that underlies 20-25% of all familial amyotrophic lateral sclerosis (FALS) cases. However, the specific mechanism of mutant SOD1 toxicity has remained elusive. Using the complementary techniques of atomic force microscopy (AFM), electrophysiology, and cell and molecular biology, here we examine the structure and activity of A4VSOD1, a mutant SOD1. AFM of A4VSOD1 reconstituted in lipid membrane shows discrete tetrameric pore-like structure with outer and inner diameters 12.2 and 3.0 nm respectively. Electrophysiological recordings show distinct ionic conductances across bilayer for A4VSOD1 and none for wildtype SOD1. Mouse neuroblastoma cells exposed to A4VSOD1 undergo membrane depolarization and increases in intracellular calcium. These results provide compelling new evidence that a mutant SOD1 is capable of disrupting cellular homeostasis via an unregulated ion channel mechanism. Such a toxic channel mechanism presents a new therapeutic direction for ALS research. (C) 2011 Elsevier Inc. All rights reserved.

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