Axonal stress kinase activation and tau misbehavior induced by kinesin-1 transport defects.
Many neurodegenerative diseases exhibit axonal pathology, transport defects, and aberrant phosphorylation and aggregation of the microtubule binding protein tau. While mutant tau protein in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP17) causes aberrant microtubule binding and assembly of tau into filaments, the pathways leading to tau-mediated neurotoxicity in Alzheimer's disease and other neurodegenerative disorders in which tau protein is not genetically modified remain unknown. To test the hypothesis that axonal transport defects alone can cause pathological abnormalities in tau protein and neurodegeneration in the absence of mutant tau or amyloid beta deposits, we induced transport defects by deletion of the kinesin light chain 1 (KLC1) subunit of the anterograde motor kinesin-1. We found that upon aging, early selective axonal transport defects in mice lacking the KLC1 protein (KLC1-/-) led to axonopathies with cytoskeletal disorganization and abnormal cargo accumulation. In addition, increased c-jun N-terminal stress kinase activation colocalized with aberrant tau in dystrophic axons. Surprisingly, swollen dystrophic axons exhibited abnormal tau hyperphosphorylation and accumulation. Thus, directly interfering with axonal transport is sufficient to activate stress kinase pathways initiating a biochemical cascade that drives normal tau protein into a pathological state found in a variety of neurodegenerative disorders including Alzheimer's disease.
Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA.
Tomás L
TL
Falzone
Gorazd B
GB
Stokin
Concepción
C
Lillo
Elizabeth M
EM
Rodrigues
Eileen L
EL
Westerman
David S
DS
Williams
Lawrence S B
LS
Goldstein
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000367:Age Factors; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000235:genetics; D006624:Hippocampus / Q000166:cytology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D016547:Kinesins; D007734:Kymography / Q000379:methods; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000648:ultrastructure; D015388:Organelles / Q000378:metabolism / Q000648:ultrastructure; D021381:Protein Transport / Q000235:genetics; D018709:Statistics, Nonparametric; D013312:Stress, Physiological / Q000502:physiology*; D014162:Transfection / Q000379:methods; D016875:tau Proteins / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D016564:Amyloid beta-Protein Precursor; C000715695:Kns2 protein, mouse; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; C485184:enhanced green fluorescent protein; D016875:tau Proteins; D049452:Green Fluorescent Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D016547:Kinesins