Structure and function of the apoA-IV T347S and Q360H common variants.
Human apolipoprotein A-IV (apoA-IV) is involved in chylomicron assembly and secretion, and in reverse cholesterol transport. Several apoA-IV isoforms exist, the most common in Caucasian populations being apoA-IV-1a (T347S) and apoA-IV-2 (Q360H). The objective of the present study was to investigate the impact of these common aminoacid substitutions on the ability of apoA-IV to bind lipids, to promote cell cholesterol efflux via ABCA1, and to maintain endothelial homeostasis. Recombinant forms of wild-type apoA-IV, apoA-IV Q360H, and apoA-IV T347S were produced in Escherichia coli. ApoA-IV Q360H and apoA-IV T347S showed a slightly higher alpha-helical content compared to wild-type apoA-IV, and associated with phospholipids faster than wild-type apoA-IV. The capacity to promote ABCA1-mediated cholesterol efflux was significantly greater for the apoA-IV T347S than the other apoA-IV isoforms. No differences were observed in the ability of apoA-IV isoforms to inhibit the production of VCAM-1 and IL-6 in TNFalpha-stimulated endothelial cells. In conclusion, the apoA-IV T347S common variant has increased lipid binding properties and cholesterol efflux capacity, while the apoA-IV Q360H variant has only slightly increased lipid binding properties. The two common aminoacid substitutions have no effect on the ability of apoA-IV to maintain endothelial homeostasis.
Gomaraschi
Monica
M
Center E. Grossi Paoletti, Department of Pharmacological Sciences, Università degli Studi di Milano, 20133 Milano, Italy.
Putt
Wendy E
WE
Pozzi
Silvia
S
Iametti
Stefania
S
Barbiroli
Alberto
A
Bonomi
Francesco
F
Favari
Elda
E
Bernini
Franco
F
Franceschini
Guido
G
Talmud
Philippa J
PJ
Calabresi
Laura
L
D019943:Amino Acid Substitution; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001054:Apolipoproteins A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005973:Glutamine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis; D050356:Lipid Metabolism; D008075:Lipoproteins, HDL / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D017433:Protein Structure, Secondary; D012694:Serine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013912:Threonine / Q000737:chemistry / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001054:Apolipoproteins A; D015850:Interleukin-6; D008075:Lipoproteins, HDL; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; C022205:apolipoprotein A-IV; D005973:Glutamine; D013912:Threonine; D012694:Serine; D006639:Histidine; D002784:Cholesterol