Laminin-5, consisting of the ␣3, ␤3, and ␥2 chains, is localized in the skin basement membrane and supports the structural stability of the epidermo-dermal linkage and regulates various cellular functions. The ␣ chains of laminins have been shown to have various biological activities. In this study, we identified a sequence of the ␣3 chain C-terminal globular domain (LG1-LG5 modules) required for both heparin binding and cell adhesion using recombinant proteins and synthetic peptides. We found that the LG3 and LG4 modules have activity for heparin binding and that LG4 has activity for cell adhesion. Studies with synthetic peptides delineated the A3G75aR sequence (NSFMALYLSKGR, residues 1412-1423) within LG4 as a major site for both heparin and cell binding. Substitution mutations in LG4 and A3G75aR identified the Lys and Arg of the A3G75aR sequence as critical for these activities. Cell adhesion to LG4 and A3G75aR was inhibited by heparitinase I treatment of cells, suggesting that cell binding to the A3G75aR site was mediated by cell surface heparan sulfate proteoglycans. We showed by affinity chromatography that syndecan-2 from fibroblasts bound to LG4. Solid-phase assays confirmed that syndecan-2 interacted with the A3G75aR peptide sequence. Stably transfected 293T cells with expression vectors for syndecan-2 and -4, but not glypican-1, specifically adhered to LG4 and A3G75aR. These results indicate that the A3G75aR sequence within the laminin ␣3 LG4 module is responsible for cell adhesion and suggest that syndecan-2 and -4 mediate this activity.Laminins are extracellular proteins primarily present at the basement membrane, where they provide structural stability and exert many biological functions, including cell adhesion, migration, proliferation, and differentiation, and they are also involved in angiogenesis and tumor invasion (for reviews, see Refs. 1 and 2). Laminins are a large family of glycoproteins, consisting of at least 12 isoforms (laminin-1 to -12) (3-5). Each laminin is composed of three different chains, ␣, ␤, and ␥. There are 11 laminin chains, five ␣ chains (␣1-␣5), three ␤ chains (␤1-␤3), and three ␥ chains (␥1-␥3), whose expression is regulated temporarily and specially during development and tissue repair. Three chains are assembled into a cross-shaped heterotrimer (␣␤␥) by forming a triple-stranded coiled-coil structure through the ␣-helical domain of each chain (6, 7).Laminin-5 (␣3␤3␥2) is a component of anchoring fibrils and forms a complex with the hemidesmosome apparatus and stabilizes the basement membrane structure by forming supramolecular complexes with laminin-6 and -7, collagen VII (8, 9), and fibulin-2 (10). Mutations in laminin-5 (11, 12) cause congenital skin blister diseases junctional epidermolysis bullosa. Disruption of the laminin ␣3 gene in mice resulted in abnormal hemidesmosomes and blister formation in the skin (13). Laminin-5 is also shown to be an adhesive substrate for keratinocytes (14). In these processes, the ␣ 3 ␤ 1 integrin was identified as a cellular recepto...

Gene targeting of a member of small leucine-rich repeat proteoglycans demonstrates that collagen fibrillogenesis is mediated by a set of extracellular matrix components, which interact with collagen. Collagen-associated protein dermatopontin knockout mice were generated in order to analyze the biologic involvement of dermatopontin in the formation of collagen fibrils. Although dermatopontin-null mice did not exhibit any obvious anatomical abnormality, skin elasticity was increased. Skin tensile tests revealed that the initial elastic modulus was 57% lower in dermatopontin-null mice than in wild-type mice, and that maximum tensile strength was similar. Remarkably, light microscopy study showed a significant decrease in the relative thickness of the dermis in dermatopontin-null mice compared with wild-type mice (45.2 +/- 3.09% and 57.8 +/- 4.25%, respectively). The skin collagen content was 40% lower in dermatopontin-null than in wild-type mice. Collagen fibrils in dermatopontin-null mice showed a great variety in diameter and irregular contours under the electron microscope. These data indicate that dermatopontin plays a critical role in elasticity of skin and collagen accumulation attributed to collagen fibrillogenesis in vivo.

Recently, we isolated human IgG from normal human sera (NHS) using lipooligosaccharide (LOS) from gonococcal strain JW31R as an affinity ligand. We provided evidence that the oligosaccharide (OS) moiety of LOS was immunogenic in humans and that NHS contains functional antibodies that bind to the branched OS.

We reported a case of a 45-year-old woman with encapsulated necrosis associated with Behçet's syndrome. The lesions were characterized by multiple, small subcutaneous nodules on the extremities. Histologically, a nodule consisted of degenerative adipocytes encapsulated by fibrous tissue. A membranocystic lesion was also observed in the cavity of the nodule. The patient had a long-term history of Behçet's syndrome and suffered from erythematous subcutaneous nodules, resembling erythema nodosum on the extremities with a tendency to recurrence. These observations indicate that Behçet's syndrome could be implicated in the development of encapsulated necrosis as an underlying disease.

Vα14 natural killer T (NKT) cells produce large amounts of both IL-4 and IFN-γ upon stimulation with a ligand, α-galactosylceramide (α-GalCer), and play a crucial role in various immune responses, including allergic diseases. Interestingly, Vα14 NKT cells are not essential for the induction of IgE responses but rather induce suppression of specific IgE production upon activation. The suppression in the IgE production is not detected either in Vα14 NKT cell-deficient mice or in IFN-γ-deficient mice. Thus, activated Vα14 NKT cells are likely to exert a potent suppressive activity on Th2 cell differentiation and subsequent IgE production by producing a large amount of IFN-γ. In marked contrast, little regulatory effect of IL-4 produced by Vα14 NKT cells on Th2 cell differentiation is suggested.