Loss of c-Jun N-terminal kinase-interacting protein-1 does not affect axonal transport of the amyloid precursor protein or A production

Disruption to axonal transport is an early pathological feature in Alzheimers disease. The amyloid precursor protein (APP) is a key axonal transport cargo in Alzheimers disease since perturbation of its transport increases APP processing and production of amyloid- peptide (A) that is deposited in the brains of Alzheimers disease patients. APP is transported anterogradely through axons on kinesin-1 motors. One favoured route for attachment of APP to kinesin-1 involves the scaffolding protein c-Jun N-terminal kinase-interacting protein-1 (JIP1), which has been shown to bind both APP and kinesin-1 light chain (KLC). However, direct experimental evidence to support a role of JIP1 in APP transport is lacking. Notably, the effect of loss of JIP1 on movement of APP through axons of living neurons, and the impact of such loss on APP processing and A production has not been reported. To address these issues, we monitored how siRNA mediated loss of JIP1 influenced transport of enhanced green fluorescent protein (EGFP)-tagged APP through axons and production of endogenous A in living neurons. Surprisingly, we found that knockdown of JIP1 did not affect either APP transport or A production. These results have important implications for our understanding of APP trafficking in Alzheimers disease.