KINESIN-1, AMYLOID PRECURSOR PROTEIN (APP)-VESICLE TRANSPORT MOTOR INTERACTS WITH FUN14 DOMAIN CONTAINING 1 (FUNDC1) VIA THE TETRATRICOPEPTIDE REPEAT DOMAIN OF KLC1

Abstract

Mutations of the amyloid precursor protein (APP) cause for the formation of amyloid-β peptides. These peptides play a key role in Alzheimer's diseases. The tetratricopeptide repeat (TPR) domain of kinesin light chain 1 (KLC1) may be responsible for binding APP either directly or via interaction with C-jun N-terminal kinase-interacting protein 1 (JIP1). However, the binding partners of the TPR domain of KLCs have not yet been fully identified. We were used the yeast two-hybrid system to identify the binding proteins that interact with the TPR domain of KLC1. The binding affinity was quantified by measuring β-galactosidase activity in liquid cultures of yeast transformed cells. Direct interaction between binding proteins and KLC1 in mammalian cells as well as in vitro was assayed using the co-immunoprecipitation with the antibodies. The cellular co-localization in cells was used the immunocytochemistry. We revealed an interaction between the TPR domain of KLC1 and FUN14 domain-containing protein 1 (FUNDC1), which is a mitochondrial outer membrane protein mediating hypoxia-induced mitophagy. FUNDC1 bound to the six TPR motif-containing regions of KLC1 and did not interact with KIF5B (a motor subunit of kinesin-1) and KIF3A (a motor subunit of kinesin-2). The cytoplasmic amino N-terminal domain of FUNDC1 is essential for interaction with KLC1. When co-expressed in HEK-293T cells, FUNDC1 co-localized with KLC1 and co-immunoprecipitated with KLC1, but not KIF5B. These results suggest that KLC1 may modulate mitophagy through the interaction with FUNDC1.