title: Cholesterol Modifies Huntingtin Binding to, Disruption of, and Aggregation on Lipid Membranes.
abstract: Huntington's disease (HD) is an inherited neurodegenerative disease caused by abnormally long CAG-repeats in the huntingtin gene that encode an expanded polyglutamine (polyQ) domain near the N-terminus of the huntingtin (htt) protein. Expanded polyQ domains are directly correlated to disease-related htt aggregation. Htt is found highly associated with a variety of cellular and subcellular membranes that are predominantly comprised of lipids. Since cholesterol homeostasis is altered in HD, we investigated how varying cholesterol content modifies the interactions between htt and lipid membranes. A combination of Langmuir trough monolayer techniques, vesicle permeability and binding assays, and in situ atomic force microscopy were used to directly monitor the interaction of a model, synthetic htt peptide and a full-length htt-exon1 recombinant protein with model membranes comprised of total brain lipid extract (TBLE) and varying amounts of exogenously added cholesterol. As the cholesterol content of the membrane increased, the extent of htt insertion decreased. Vesicles containing extra cholesterol were resistant to htt-induced permeabilization. Morphological and mechanical changes in the bilayer associated with exposure to htt were also drastically altered by the presence of cholesterol. Disrupted regions of pure TBLE bilayers were grainy in appearance and associated with a large number of globular aggregates. In contrast, morphological changes induced by htt in bilayers enriched in cholesterol were plateau-like with a smooth appearance. Collectively, these observations suggest that the presence and amount of cholesterol in lipid membranes play a critical role in htt binding and aggregation on lipid membranes.
authors.affiliation: The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.affiliation: Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania 17325, United States.
authors.forename: Warren A
authors.initials: WA
authors.lastname: Campbell
authors.affiliation: The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.
authors.forename: Maxmore
authors.initials: M
authors.lastname: Chaibva
authors.affiliation: The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.
authors.forename: Pranav
authors.initials: P
authors.lastname: Jain
authors.affiliation: The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.
authors.forename: Ashley E
authors.initials: AE
authors.lastname: Leslie
authors.affiliation: Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania 17325, United States.
authors.forename: Shelli L
authors.initials: SL
authors.lastname: Frey
authors.affiliation: The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26505, United States.|NanoSAFE, P.O. Box 6223, West Virginia University, Morgantown, West Virginia 26506, United States.|The Center for Neurosciences, West Virginia University, Morgantown, West Virginia 26505, United States.
authors.forename: Justin
authors.initials: J
authors.lastname: Legleiter
mesh_terms: D002784:Cholesterol / Q000378:metabolism*; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010539:Permeability; D066263:Protein Aggregation, Pathological / Q000378:metabolism; D011485:Protein Binding; D053835:Unilamellar Liposomes / Q000378:metabolism*
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D008563:Membrane Lipids; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D053835:Unilamellar Liposomes; D002784:Cholesterol