Cellular interactions with advanced glycation end products (AGE)-modified proteins are known to induce several biological responses, not only endocytic uptake and degradation, but also the induction of cytokines and growth factors, combined responses that may be linked to the development of diabetic vascular complications. In this study we demonstrate that A549 cells, a human pulmonary epithelial cell line, possess a specific binding site for AGE-modified bovine serum albumin (AGE-BSA) (K(d) = 27.8 nM), and additionally for EN-RAGE (extracellular newly identified RAGE binding protein) (K(d) = 118 nM). Western blot and RT-PCR analysis showed that RAGE (receptor for AGE) is highly expressed on A549 cells, while the expression of other known AGE-receptors such as galectin-3 and SR-A (class A scavenger receptor), are below the level of detection. The binding of (125)I-AGE-BSA to these cells is inhibited by unlabeled AGE-BSA, but not by EN-RAGE. In contrast, the binding of (125)I-EN-RAGE is significantly inhibited by unlabeled EN-RAGE and soluble RAGE, but not by AGE-BSA. Our results indicate that A549 cells possess at least two binding sites, one specific for EN-RAGE and the other specific for AGE-BSA. The latter receptor on A549 cells is distinct from the scavenger receptor family and RAGE.

Abnormal retention of v vF508 CFTR (cystic ¢brosis transmembrane conductance regulator) in the endoplasmic reticulum is a major cause of cystic ¢brosis (CF). We show that calnexin v v185^520 but not calnexin can partially reverse the mislocalization of v vF508 CFTR. This 256-amino acid protein has neither the transmembrane domain nor the P domain of calnexin. Calnexin v v185^520 interacted with CFTR directly, and was secreted into the extracellular compartment over time. Forty-eight hours after transfection into CHO cells, calnexin v v185^520 increased the conversion of immature v vF508 CFTR into mature v vF508 CFTR. In immortalized human CF cell lines expressing v vF508 CFTR, a halide e¥ux assay showed that calnexin v v185^520 partially restored CFTR function. These data indicate that calnexin v v185^520 may give a clue to develop the therapeutic way of cystic ¢brosis with v vF508 CFTR. ß

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Wesearched for a newaggregation factor, and found one wenamed3315-AFin the culture filtrate of Streptomyces sp. strain No. A-3315.3315-AFwas purified by active carbon treatment, ethanol precipitation, gel filtration on Sepharose 2B, ether extraction, silica gel chromatography and gel filtration on Sephadex LH-20. 3315-AF was found to be a triglyceride which consists of myristic acid, pentadecanoic acid, and palmitic acid. The aggregation activity of 3315-AFwas maximum around pH 8.0 at 30cC and the activity increased by addition of metallic ions such as calcium and cobalt. Hyaluronic acid, ovalbumin, BSA, and casein inhibited the aggregation activity. 3315-AFaggregated Proteus vulgaris and HeLacells as well as Serratia marcescens and weakly aggregated Saccharomyces cerevisiae, Candida albicans, C. neoformans, and Leukemia P388, but it was inert to human erythrocytes and Sarcoma 180.