Functional impairment of two novel mutations detected in lipoprotein-associated phospholipase A2 (Lp-PLA2) deficiency patients.
Plasma lipoprotein-associated phospholipase A2 (Lp-PLA2), also known as platelet-activating factor (PAF) acetylhydrolase (PAF-AH), is a member of the serine-dependent class of A2 phospholipases that hydrolyze sn2-ester bonds of fragmented or oxidized phospholipids at sites where atherosclerotic plaques are forming. Most circulating Lp-PLA2 is bound to low-density lipoprotein (LDL) particles in plasma and the rest to high-density lipoprotein (HDL). Deficiency of Lp-PLA2 is a predisposing factor for cardiovascular diseases in the Japanese population. We describe here two novel mutations of the gene encoding Lp-PLA2, InsA191 and I317N in Japanese subjects. The first patient, with partial Lp-PLA2 deficiency, was heterozygous for the InsA191 mutation; macrophages from this patient secreted only half the normal amount of Lp-PLA2 in vitro. The other patient, who showed complete Lp-PLA2 deficiency, was a compound heterozygote for the novel I317N mutation and a common V279F mutation; macrophages from that patient failed to secrete any Lp-PLA2. Measurement of Lp-PLA2 mass, activity and Western blotting verified impaired production and secretion of the enzyme after transfection of mutant construct into COS-7 cells. These results indicated that both novel mutants, InsA191 and I317N, impair function of the Lp-PLA2 gene.
Ishihara
Mitsuaki
M
Department of Advanced Medical Technology and Development, BML, Inc., Kawagoe, Japan.
Iwasaki
Tadao
T
Department of Advanced Medical Technology and Development, BML, Inc., Kawagoe, Japan.
Nagano
Makoto
M
Department of Advanced Medical Technology and Development, BML, Inc., Kawagoe, Japan.
Ishii
Jun
J
Internal Medicine, Hokkaido Hospital for Social Health Insurance, Sapporo, Japan.
Takano
Mayumi
M
Department of Advanced Medical Technology and Development, BML, Inc., Kawagoe, Japan.
Kujiraoka
Takeshi
T
Department of Advanced Medical Technology and Development, BML, Inc., Kawagoe, Japan.
Tsuji
Masahiro
M
Institute of Medical Science, Health Sciences University of Hokkaido, Sapporo, Japan.
Hattori
Hiroaki
H
Department of Advanced Medical Technology and Development, BML, Inc., Kawagoe, Japan.
Emi
Mitsuru
M
Department of Molecular Biology, Institute of Gerontology, Nippon Medical School, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki 211-8533, Japan. memi@nms.ac.jp.
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000368:Aged; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D019556:COS Cells; D003470:Culture Media / Q000494:pharmacology; D004952:Esters; D005260:Female; D006579:Heterozygote; D006801:Humans; D007564:Japan; D008077:Lipoproteins, LDL / Q000737:chemistry; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009000:Monocytes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D010741:Phospholipases A / Q000097:blood / Q000172:deficiency* / Q000235:genetics*; D054467:Phospholipases A2; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012694:Serine / Q000737:chemistry
D003470:Culture Media; D004952:Esters; D008077:Lipoproteins, LDL; D012694:Serine; D010741:Phospholipases A; D054467:Phospholipases A2; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D010100:Oxygen