title: Interaction of Huntingtin-associated protein-1 with kinesin light chain: implications in intracellular trafficking in neurons.
abstract: Huntingtin-associated protein-1 (HAP1) was initially identified as an interacting partner of huntingtin, the Huntington disease protein. Unlike huntingtin that is ubiquitously expressed throughout the brain and body, HAP1 is enriched in neurons, suggesting that its dysfunction could contribute to Huntington disease neuropathology. Growing evidence has demonstrated that HAP1 and huntingtin are anterogradely transported in axons and that the abnormal interaction between mutant huntingtin and HAP1 may impair axonal transport. However, the exact role of HAP1 in anterograde transport remains unclear. Here we report that HAP1 interacts with kinesin light chain, a subunit of the kinesin motor complex that drives anterograde transport along microtubules in neuronal processes. The interaction of HAP1 with kinesin light chain is demonstrated via a yeast two-hybrid assay, glutathione S-transferase pull down, and coimmunoprecipitation. Furthermore, HAP1 is colocalized with kinesin in growth cones of neuronal cells. We also demonstrated that knocking down HAP1 via small interfering RNA suppresses neurite outgrowth of PC12 cells. Analysis of live neuronal cells with fluorescence microscopy and fluorescence recovery after photobleaching demonstrates that suppressing the expression of HAP1 or deleting the HAP1 gene inhibits the kinesin-dependent transport of amyloid precursor protein vesicles. These studies provide a molecular basis for the participation of HAP1 in anterograde transport in neuronal cells.
authors.affiliation: Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: John Russel
authors.initials: JR
authors.lastname: McGuire
authors.forename: Juan
authors.initials: J
authors.lastname: Rong
authors.forename: Shi-Hua
authors.initials: SH
authors.lastname: Li
authors.forename: Xiao-Jiang
authors.initials: XJ
authors.lastname: Li
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000737:chemistry; D000818:Animals; D001369:Axons / Q000378:metabolism; D001692:Biological Transport; D015153:Blotting, Western; D005982:Glutathione Transferase / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D016547:Kinesins / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism; D015233:Models, Statistical; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D016716:PC12 Cells; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D016564:Amyloid beta-Protein Precursor; C096896:HAP1 protein, human; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D005982:Glutathione Transferase; D016547:Kinesins