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Articles by J Wada
Total Records ( 2 ) for J Wada
  H Ashida , A Miyake , M Kiyohara , J Wada , E Yoshida , H Kumagai , T Katayama and K. Yamamoto

Bifidobacteria are predominant bacteria present in the intestines of breast-fed infants and offer important health benefits for the host. Human milk oligosaccharides are one of the most important growth factors for bifidobacteria and are frequently fucosylated at their non-reducing termini. Previously, we identified 1,2--l-fucosidase (AfcA) belonging to the novel glycoside hydrolase (GH) family 95, from Bifidobacterium bifidum JCM1254 (Katayama T, Sakuma A, Kimura T, Makimura Y, Hiratake J, Sakata K, Yamanoi T, Kumagai H, Yamamoto K. 2004. Molecular cloning and characterization of Bifidobacterium bifidum 1,2--l-fucosidase (AfcA), a novel inverting glycosidase (glycoside hydrolase family 95). J Bacteriol. 186:4885–4893). Here, we identified a gene encoding a novel 1,3–1,4--l-fucosidase from the same strain and termed it afcB. The afcB gene encodes a 1493-amino acid polypeptide containing an N-terminal signal sequence, a GH29 -l-fucosidase domain, a carbohydrate binding module (CBM) 32 domain, a found-in-various-architectures (FIVAR) domain and a C-terminal transmembrane region, in this order. The recombinant enzyme was expressed in Escherichia coli and was characterized. The enzyme specifically released 1,3- and 1,4-linked fucosyl residues from 3-fucosyllactose, various Lewis blood group substances (a, b, x, and y types), and lacto-N-fucopentaose II and III. However, the enzyme did not act on glycoconjugates containing 1,2-fucosyl residue or on synthetic -fucoside (p-nitrophenyl--l-fucoside). The afcA and afcB genes were introduced into the B. longum 105-A strain, which has no intrinsic -l-fucosidase. The transformant carrying afcA could utilize 2'-fucosyllactose as the sole carbon source, whereas that carrying afcB was able to utilize 3-fucosyllactose and lacto-N-fucopentaose II. We suggest that AfcA and AfcB play essential roles in degrading 1,2- and 1,3/4-fucosylated milk oligosaccharides, respectively, and also glycoconjugates, in the gastrointestinal tracts.

  K Sarai , K Shikata , Y Shikata , K Omori , N Watanabe , M Sasaki , S Nishishita , J Wada , N Goda , N Kataoka and H. Makino

Recently, sphingosine 1-phosphate (S1P) has been highlighted as an endothelial barrier-stabilizing mediator. FTY720 is a S1P analog originally developed as a novel immunosuppressant. The phosphorylated form of FTY720 binds to S1P receptors to exert S1P-like biological effects, suggesting endothelial barrier promotion by FTY720. To elucidate whether FTY720 induces signaling events related to endothelial barrier enhancement under hyperglycemic conditions, human microvascular endothelial cells (HMVECs) preincubated with hyperglycemic (30 mM) medium were treated with 100 nM FTY720 for 3 h. Immunofluorescent microscopy and coprecipitation study revealed FTY720-induced focal adhesion kinase (FAK)-associated adherens junction (AJ) assembly at cell-cell contacts coincident with formation of a prominent cortical actin ring. FTY720 also induced transmonolayer electrical resistance (TER) augmentation in HMVEC monolayers in both normoglycemic and hyperglycemic conditions, implying endothelial barrier enhancement. Similar to S1P, site-specific FAK tyrosine phosphorylation analysis revealed FTY720-induced FAK [Y576] phosphorylation without phosphorylation of FAK [Y397/Y925]. Furthermore, FTY720 conditioned the phosphorylation profile of FAK [Y397/Y576/Y925] in hyperglycemic medium to the same pattern observed in normoglycemic medium. FTY720 challenge resulted in small GTPase Rac activation under hyperglycemic conditions, whereas increased Rho activity in hyperglycemic medium was restored to the basal level. Rac protein depletion by small interfering RNA (siRNA) technique completely abolished FTY720-induced FAK [Y576] phosphorylation. These findings strongly suggest the barrier protective effect of FTY720 on HMVEC monolayers in hyperglycemic medium via S1P signaling, further implying the possibility of FTY720 as a therapeutic agent of diabetic vascular disorder.

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