Interaction of Huntingtin-associated Protein-1 with Kinesin Light Chain
IMPLICATIONS IN INTRACELLULAR TRAFFICKING IN NEURONS*
- 1 To whom correspondence should be addressed: Dept. of Human Genetics, Emory University School of Medicine, 615 Michael St., Atlanta GA 30322. Tel.: 404-727-3290; Fax: 404-727-3949; E-mail: xiaoli{at}genetics.emory.edu.
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.
Footnotes
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↵2 The abbreviations used are: HAP1, huntingtin-associated protein 1; KLC, kinesin light chain; KHC, kinesin heavy chain; WT-wild type; GFP, green fluorescent protein; YFP, yellow fluorescent protein; RFP, red fluorescent protein; siRNA-small interfering RNA; APP, amyloid precursor protein; FRAP-fluorescence recovery after photobleaching; GST, glutathione S-transferase; NGF, nerve growth factor.
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↵* This work was supported by National Institutes of Health Grants NS36232 and AG19206. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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The on-line version of this article (available at http://www.jbc.org) contains supplemental movies 1 and 2.
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- Received September 7, 2005.
- Revision received December 7, 2005.
- The American Society for Biochemistry and Molecular Biology, Inc.
