14-3-3 protein binds to the low molecular weight neurofilament (NFL) mRNA 3′ UTR

We have previously reported that altered stability of low molecular weight neurofilament (NFL) mRNA in lumbar spinal cord homogenates in amyotrophic lateral sclerosis (ALS) is associated with altered expression of trans-acting 3′ UTR mRNA binding proteins. We have identified two hexanucleotide motifs as the main cis elements and, using LC/MS/MS of peptide digests of NFL 3′ UTR interacting proteins from human spinal cord, observed that 14-3-3 proteins interact with these motifs. 14-3-3 β, ζ, τ, γ, and η isoforms were found to be expressed in human spinal cord. Each isoform was expressed in vitro and shown to interact with NFL 3′ UTR mRNA. Mutation of one or both motifs resulted in decreased 14-3-3 interaction, changes in predicted mRNA structure or alteration in stability of the mRNA. These data show a novel interaction for 14-3-3 with NFL mRNA, and suggests that 14-3-3 may play a role in regulating NFL mRNA stability.