To search for a gene(s) conferring susceptibility to diabetic nephropathy (DN), we genotyped over 80,000 genebased single nucleotide polymorphisms (SNPs) in Japanese patients and identified that the engulfment and cell motility 1 gene (ELMO1) was a likely candidate for conferring susceptibility to DN, in view of the significant association of an SNP in this gene with the disease (intron 18؉9170, GG vs. GA؉AA, 2 ‫؍‬ 19.9, P ‫؍‬ 0.000008; odds ratio 2.67, 95% CI 1.71-4.16). In situ hybridization (ISH) using the kidney of normal and diabetic mice revealed that ELMO1 expression was weakly detectable mainly in tubular and glomerular epithelial cells in normal mouse kidney and was clearly elevated in the kidney of diabetic mice. Subsequent in vitro analysis revealed that ELMO1 expression was elevated in cells cultured under high glucose conditions (25 mmol/l) compared with cells cultured under normal glucose conditions (5.5 mmol/l). Furthermore, we identified that the expression of extracellular matrix protein genes, such as type 1 collagen and fibronectin, were increased in cells that overexpress ELMO1, whereas the expression of matrix metalloproteinases was decreased. These results indicate that ELMO1 is a novel candidate gene that both confers susceptibility to DN and plays an important role in the development and progression of this disease. Diabetes 54:1171-1178, 2005

Group X secretory phospholipase A 2 (sPLA 2 -X) possesses several structural features characteristic of both group IB and IIA sPLA 2 s (sPLA 2 -IB and -IIA) and is postulated to be involved in inflammatory responses owing to its restricted expression in the spleen and thymus. Here, we report the purification of human recombinant COOH-terminal His-tagged sPLA 2 -X, the preparation of its antibody, and the purification of native sPLA 2 -X. The affinity-purified sPLA 2 -X protein migrated as various molecular species of 13-18 kDa on SDS-polyacrylamide gels, and N-glycosidase F treatment caused shifts to the 13-and 14-kDa bands. NH 2 -terminal amino acid sequencing analysis revealed that the 13-kDa form is a putative mature sPLA 2 -X and the 14-kDa protein possesses a propeptide of 11 amino acid residues attached at the NH 2 termini of the mature protein. Separation with reverse-phase high performance liquid chromatography revealed that N-linked carbohydrates are not required for the enzymatic activity and prosPLA 2 -X has a relatively weak potency compared with the mature protein. The mature sPLA 2 -X induced the release of arachidonic acid from phosphatidylcholine more efficiently than other human sPLA 2 groups (IB, IIA, IID, and V) and elicited a prompt and marked release of arachidonic acid from human monocytic THP-1 cells compared with sPLA 2 -IB and -IIA with concomitant production of prostaglandin E 2 . A prominent release of arachidonic acid was also observed in sPLA 2 -X-treated human U937 and HL60 cells. Immunohistochemical analysis of human lung preparations revealed its expression in alveolar epithelial cells. These results indicate that human sPLA 2 -X is a unique N-glycosylated sPLA 2 that releases arachidonic acid from human myeloid leukemia cells more efficiently than sPLA 2 -IB and -IIA.Phospholipase A 2 (PLA 2 ) 1 comprises a diverse family of lipolytic enzymes that hydrolyze the sn-2 fatty acid ester bond of glycerophospholipids to produce free fatty acid and lysophospholipids (1, 2). PLA 2 s participate in pathophysiological processes by releasing arachidonic acid from membrane phospholipids, leading to the production of various types of proinflammatory lipid mediators, such as prostaglandins (PGs) and leukotrienes (LTs) (3). Over the past two decades, a number of PLA 2 s have been identified and characterized. From their biochemical features, these PLA 2 s are classified into several families (4), including secretory PLA 2 (sPLA 2 ) (5-11), arachidonoyl-specific cytosolic PLA 2 (cPLA 2 ) (12, 13), and Ca 2ϩ -independent PLA 2 (14).Low molecular mass sPLA 2 s (13-18 kDa) have several features including a high disulfide bond content, a requirement for millimolar concentrations of Ca 2ϩ for catalysis, and a broad specificity for phospholipids with different polar head groups and fatty acyl chains (15, 16). Mammalian sPLA 2 s are classified into different groups depending on the primary structure characterized by the number and positions of cysteine residues. At present, five types of functional sPL...

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Mammalian secretory phospholipase A 2 s (sPLA 2 s) form a family of structurally related enzymes that are involved in a variety of physiological and pathological processes via the release of arachidonic acid from membrane phospholipids or the binding to specific membrane receptors. Here, we report the cloning and characterization of a novel sPLA 2 that is the sixth isoform of the sPLA 2 family found in humans. The novel human mature sPLA 2 consists of 123 amino acids (M r ‫؍‬ 14,000) and is most similar to group IIA sPLA 2 (sPLA 2 -IIA) with respect to the number and positions of cysteine residues as well as overall identity (51%). Therefore, this novel sPLA 2 should be categorized into group II and called group IIE (sPLA 2 -IIE) following the recently identified group IID sPLA 2 (sPLA 2 -IID). The enzymatic properties of recombinant human sPLA 2 -IIE were almost identical to those of sPLA 2 -IIA and IID in terms of Ca 2؉ requirement, optimal pH, substrate specificity, as well as high susceptibility to the sPLA 2 inhibitor indoxam. Along with the biochemical properties of proteins, genetic and evolutional similarities were also observed among these three types of group II sPLA 2 s as to the chromosomal location of the human gene (1p36) and the exon/intron organization. The expression of sPLA 2 -IIE transcripts in humans was restricted to the brain, heart, lung, and placenta in contrast to broad expression profiles for sPLA 2 -IIA and -IID. In sPLA 2 -IIA-deficient mice, the expression of sPLA 2 -IIE was markedly enhanced in the lung and small intestine upon endotoxin challenge, which contrasted with the reduced expression of sPLA 2 -IID mRNA. In situ hybridization analysis revealed elevation of sPLA 2 -IIE mRNA at alveolar macrophage-like cells in the lung of endotoxin-treated mice. These findings suggest a distinct functional role of novel sPLA 2 -IIE in the progression of inflammatory processes.