title: Identification, expression and function of apolipoprotein E in annual fish Nothobranchius guentheri: implication for an aging marker.
abstract: Apolipoprotein E (apoE) is a lipid-associated protein present in both plasma and in central nervous system. Variation in apoE gene has been reported to be associated with longevity in humans as well as with aged diseases such as atherosclerosis, Alzheimer's disease, and Parkinson's disease. However, information regarding the function and structure-activity relationship of apoE in lower vertebrates is rather limited. In this study we show that the apoE gene from the annual fish Nothobranchius guentheri, NapoE, encodes a protein of 262 amino acids, which shares common structural features characteristic of mammalian apoE. We also show that like human apoE, recombinant NapoE is able to inhibit LDL oxidation, and it is the N-terminal domain of NapoE with lysine or arginine residues that plays a key role in inhibition of LDL oxidation. NapoE is predominantly expressed in the liver of N. guentheri, consistent with that in mammalian species. More importantly, we demonstrate an age-dependent down-regulation of NapoE gene, rendering it a suitable biomarker of aging. This lays a foundation for further study of the role of apoE in the aging process of fish.
authors.affiliation: Department of Marine Biology and Laboratory for Evolution and Development, Ocean University of China, Qingdao, 266003, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Shang
authors.forename: Jing
authors.initials: J
authors.lastname: Luan
authors.forename: Shicui
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000375:Aging / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001057:Apolipoproteins E / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015415:Biomarkers / Q000378:metabolism; D017124:Conserved Sequence; D015536:Down-Regulation / Q000235:genetics; D005399:Fishes / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary
chemical_list: D000975:Antioxidants; D001057:Apolipoproteins E; D015415:Biomarkers; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein