Premium
[P4–090]: THE SUBCELLULAR LOCALIZATION OF TAU AND THE PROPERTIES OF MUTANT P301L TAU IN PRIMARY NEURON CULTURES
Author(s) -
Kneynsberg Andrew,
Kanaan Nicholas M.
Publication year - 2017
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2017.06.1955
Subject(s) - tauopathy , axon , soma , mutant , neuroscience , axoplasmic transport , microbiology and biotechnology , tau protein , biology , neuron , compartment (ship) , wild type , immunofluorescence , neurodegeneration , antibody , pathology , gene , immunology , genetics , medicine , alzheimer's disease , disease , oceanography , geology
Background:Tau is enriched in the axonal compartment in healthy neurons, and the mislocalization of tau into the somatodendritic compartment is important in tauopathy pathogenesis. The localization of tau in axons appears to involve the axon initial segment (AIS), which is a specialized region that acts as a retrograde barrier for tau. Disruption of AIS function and/or abnormal mutations of tau may play a role in tau mislocalization. However, many questions remain regarding how the AIS functions as a barrier and the role of tau mutations in mislocalization. Methods:We examined the timing of AIS development, the differential distribution of tau in axons, and how disease-related mutant tau affects localization in rat primary hippocampal neurons. Neurons were grown in vitro for 1-7 days and stained for AIS markers and tau antibodies. Fluorescence intensity signal was measured from the soma, across the AIS and into the distal axon. Axonal tau diffusion was assessed using fusion constructs of dendra2 (a photo-convertible fluorescent protein) and wild-type or P301L tau (mutant tau in an inherited tauopathy). Neurons were transfected and an anti-neurofascin antibody approach was used to accurately identify axons in live cells for imaging tau diffusion. Results:Development of the AIS occurs within five days, which corresponds to the induction of an axonal enrichment of tau. Tracking tau by photoconversion of dendra2 showed that wild-type tau construct did not diffuse from the axon back into the cell body, but the P301L mutant tau diffused across the AIS into the soma allowing the accumulation of significantly more tau when compared to wild-type tau. Conclusions: This research supports an association between the AIS and the selective enrichment of tau to the axonal compartment during neuronal development. Interestingly, abnormal forms of tau associated with disease may not localize appropriately in neurons because the retrograde diffusion out of the axon is not blocked by the AIS. The toxicity of P301L has centered around its greater propensity to aggregate, however, these data suggest a lack of normal tau distribution may also influence P301L taudependent effects.