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- Mendoza-Barbera, Elena, et al.
(författare)
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Structural and functional analysis of APOA5 mutations identified in patients with severe hypertriglyceridemia
- 2013
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 54:3, s. 649-661
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Tidskriftsartikel (refereegranskat)abstract
- During the diagnosis of three unrelated patients with severe hypertriglyceridemia, three APOA5 mutations [p.(Ser232_Leu235)del,p.Leu253Pro,andp.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.-Mendoza-Barbera, E., J. Julve, S. K. Nilsson, A. Lookene, J. M. Martin-Campos, R. Roig, A. M. Lechuga-Sancho, J. J. Sloan, P. Fuentes-Prior, and F. Blanco-Vaca. Structural and functional analysis of APOA5 mutations identified in patients with severe hypertriglyceridemia.
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| 2. |
- Rubio-Moscardo, Fanny, et al.
(författare)
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Rare Variants in Calcium Homeostasis Modulator 1 (CALHM1) Found in Early Onset Alzheimer's Disease Patients Alter Calcium Homeostasis
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:9, s. e74203-
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Tidskriftsartikel (refereegranskat)abstract
- Calcium signaling in the brain is fundamental to the learning and memory process and there is evidence to suggest that its dysfunction is involved in the pathological pathways underlying Alzheimer's disease (AD). Recently, the calcium hypothesis of AD has received support with the identification of the non-selective Ca2+-permeable channel CALHM1. A genetic polymorphism (p. P86L) in CALHM1 reduces plasma membrane Ca2+ permeability and is associated with an earlier age-at-onset of AD. To investigate the role of CALHM1 variants in early-onset AD (EOAD), we sequenced all CALHM1 coding regions in three independent series comprising 284 EOAD patients and 326 controls. Two missense mutations in patients (p.G330D and p.R154H) and one (p.A213T) in a control individual were identified. Calcium imaging analyses revealed that while the mutation found in a control (p.A213T) behaved as wild-type CALHM1 (CALHM1-WT), a complete abolishment of the Ca2+ influx was associated with the mutations found in EOAD patients (p.G330D and p.R154H). Notably, the previously reported p. P86L mutation was associated with an intermediate Ca2+ influx between the CALHM1-WT and the p.G330D and p. R154H mutations. Since neither expression of wild-type nor mutant CALHM1 affected amyloid beta-peptide (A beta) production or A beta-mediated cellular toxicity, we conclude that rare genetic variants in CALHM1 lead to Ca2+ dysregulation and may contribute to the risk of EOAD through a mechanism independent from the classical A beta cascade.
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