Figure 7. Overexpression of 14-3-3ζ in rat primary hippocampal neurons promotes proteosomal degradation of synaptophysin protein.

(A) 14-3-3ζ overexpression does not affect synaptophysin protein synthesis in neurons. Ln-14-3-3ζ or Ln-vector infected neurons were treated with cycloheximide or vehicle for the indicated time and analyzed for synaptophysin protein by Western blotting. Synaptophysin band intensity in each lane was normalized against the corresponding actin band and is expressed as the % of 0 hr. Values with ± SE are the average of three determinations. *p<0.005 with respect to Ln-vector infected neurons. (B) Proteosome inhibitors block the downregulation of synaptophysin protein caused by 14-3-3ζ overexpression. Primary neurons infected with Ln-14-3-3ζ or Ln-vector were treated with MG132 or lactacystin for 24 hr. Treated neurons were analyzed by Western blotting and the relative amounts were determined as per Figure 6. Values with standard error are the average of three determinations from three cultures. *p< 0.005 with respect to Ln-14-3-3ζ infected and vehicle treated neurons.