1
|
Melchior JT, Street SE, Andraski AB, Furtado JD, Sacks FM, Shute RL, Greve EI, Swertfeger DK, Li H, Shah AS, Lu LJ, Davidson WS. Apolipoprotein A-II alters the proteome of human lipoproteins and enhances cholesterol efflux from ABCA1. J Lipid Res 2017; 58:1374-1385. [PMID: 28476857 DOI: 10.1194/jlr.m075382] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/25/2017] [Indexed: 12/25/2022] Open
Abstract
HDLs are a family of heterogeneous particles that vary in size, composition, and function. The structure of most HDLs is maintained by two scaffold proteins, apoA-I and apoA-II, but up to 95 other "accessory" proteins have been found associated with the particles. Recent evidence suggests that these accessory proteins are distributed across various subspecies and drive specific biological functions. Unfortunately, our understanding of the molecular composition of such subspecies is limited. To begin to address this issue, we separated human plasma and HDL isolated by ultracentrifugation (UC-HDL) into particles with apoA-I and no apoA-II (LpA-I) and those with both apoA-I and apoA-II (LpA-I/A-II). MS studies revealed distinct differences between the subfractions. LpA-I exhibited significantly more protein diversity than LpA-I/A-II when isolated directly from plasma. However, this difference was lost in UC-HDL. Most LpA-I/A-II accessory proteins were associated with lipid transport pathways, whereas those in LpA-I were associated with inflammatory response, hemostasis, immune response, metal ion binding, and protease inhibition. We found that the presence of apoA-II enhanced ABCA1-mediated efflux compared with LpA-I particles. This effect was independent of the accessory protein signature suggesting that apoA-II induces a structural change in apoA-I in HDLs.
Collapse
Affiliation(s)
- John T Melchior
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Scott E Street
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Allison B Andraski
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Jeremy D Furtado
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Frank M Sacks
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115; Department of Genetics & Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Rebecca L Shute
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Emily I Greve
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Debi K Swertfeger
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Hailong Li
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Amy S Shah
- Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - L Jason Lu
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237.
| |
Collapse
|
2
|
Gursky O. Hot spots in apolipoprotein A-II misfolding and amyloidosis in mice and men. FEBS Lett 2014; 588:845-50. [PMID: 24561203 DOI: 10.1016/j.febslet.2014.01.066] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/08/2014] [Accepted: 01/27/2014] [Indexed: 01/06/2023]
Abstract
ApoA-II is the second-major protein of high-density lipoproteins. C-terminal extension in human apoA-II or point substitutions in murine apoA-II cause amyloidosis. The molecular mechanism of apolipoprotein misfolding, from the native predominantly α-helical conformation to cross-β-sheet in amyloid, is unknown. We used 12 sequence-based prediction algorithms to identify two ten-residue segments in apoA-II that probably initiate β-aggregation. Previous studies of apoA-II fragments experimentally verify this prediction. Together, experimental and bioinformatics studies explain why the C-terminal extension in human apoA-II causes amyloidosis and why, unlike murine apoA-II, human apoA-II normally does not cause amyloidosis despite its unusually high sequence propensity for β-aggregation.
Collapse
Affiliation(s)
- Olga Gursky
- Department of Physiology and Biophysics, Boston University School of Medicine, W329, 700 Albany Street, Boston, MA 02118, United States.
| |
Collapse
|