Lipid Peroxidation Creates Intramolecular Crosslinking of Neurofilaments

LIPID PEROXIDATION CREATES INTRAMOLECULAR CROSSLINKING OF NEUROFILAMENTS

  EA Perry; RJ Castellani; PI Moreira; SL Siedlak; PLR Harris; LM Sayre; PA Szweda; LI Szweda; X Zhu; MA Smith; G Perry   The University of Texas at San Antonio (EAP, GP); University of Maryland (RJC); University of Coimbra (PIM); Case Western Reserve University (SLS, PLRH, LMS, XZ, MAS); University of Oklahoma Health Sciences Center (PIS, LIS)  

  PURPOSE:  Lipid peroxidation generates reactive aldehydes, most notably hydroxynonenal (HNE), which covalently binds amino acid residue side chains leading to protein inactivation and insolubility. Specific adducts of lipid peroxidation have been demonstrated to be intimately associated with pathological lesions of Alzheimer disease (AD), suggesting oxidative stress is a major component in the disease. DESIGN METHODS:  Here, brain tissue from AD and control patients was examined by immunocytochemistry and immunoblotting for evidence of HNE-crosslinking modifications by using an antibody specific for a lysine-lysine crosslink. RESULTS:  While no immunolabeling of neuritic plaques or neurofibrillary tangles was detected, strong labeling of axons was noted.  Immunoblotting showed the crosslink was restricted to neurofilament medium and heavy subunit but did not change their molecular weight.  CONCLUSION:  These findings directly implicate lipid crosslinking peroxidation products as accumulating not in the lesions but rather in lysine rich neurofilaments in the cytosol.  Surprisingly the modification was restricted to intramolecular sites.

GRANT SUPPORT:  This project was supported by grants from the National Center for Research Resources (5 G12RR013646-12) and the National Institute on Minority Health and Health Disparities (G12MD007591) from the National Institutes of Health.