title: Structural and functional analysis of APOA5 mutations identified in patients with severe hypertriglyceridemia.
abstract: During the diagnosis of three unrelated patients with severe hypertriglyceridemia, three APOA5 mutations [p.(Ser232_Leu235)del, p.Leu253Pro, and p.Asp332ValfsX4] were found without evidence of concomitant LPL, APOC2, or GPIHBP1 mutations. The molecular mechanisms by which APOA5 mutations result in severe hypertriglyceridemia remain poorly understood, and the functional impairment/s induced by these specific mutations was not obvious. Therefore, we performed a thorough structural and functional analysis that included follow-up of patients and their closest relatives, measurement of apoA-V serum concentrations, and sequencing of the APOA5 gene in 200 nonhyperlipidemic controls. Further, we cloned, overexpressed, and purified both wild-type and mutant apoA-V variants and characterized their capacity to activate LPL. The interactions of recombinant wild-type and mutated apoA-V variants with liposomes of different composition, heparin, LRP1, sortilin, and SorLA/LR11 were also analyzed. Finally, to explore the possible structural consequences of these mutations, we developed a three-dimensional model of full-length, lipid-free human apoA-V. A complex, wide array of impairments was found in each of the three mutants, suggesting that the specific residues affected are critical structural determinants for apoA-V function in lipoprotein metabolism and, therefore, that these APOA5 mutations are a direct cause of hypertriglyceridemia.
authors: Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain.
authors: Elena
authors: E
authors: Mendoza-Barberá
authors: Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, 08017 Barcelona, Spain.
authors: Josep
authors: J
authors: Julve
authors: Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE90187, Sweden.
authors: Stefan K
authors: SK
authors: Nilsson
authors: Department of Chemistry, Tallinn Technical University, Tallinn 12618, Estonia.
authors: Aivar
authors: A
authors: Lookene
authors: Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain.
authors: Jesús M
authors: JM
authors: Martín-Campos
authors: Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain.
authors: Rosa
authors: R
authors: Roig
authors: Unidad de Endocrinología Pediátrica, Hospital Universitario Puerta del Mar, 11009 Cádiz, Spain.
authors: Alfonso M
authors: AM
authors: Lechuga-Sancho
authors: Eli Lilly and Company, Indianapolis, IN 46285.
authors: John H
authors: JH
authors: Sloan
authors: Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain.
authors: Pablo
authors: P
authors: Fuentes-Prior
authors: Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, 08017 Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08025 Barcelona, Spain.
authors: Francisco
authors: F
authors: Blanco-Vaca
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000072040:Apolipoprotein A-V; D001054:Apolipoproteins A / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D015228:Hypertriglyceridemia / Q000235:genetics*; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D055815:Young Adult
chemical_list: C437704:APOA5 protein, human; D000072040:Apolipoprotein A-V; D001054:Apolipoproteins A; D008081:Liposomes