Kiyomitsu Nara

Cell cycle-dependent changes in tissue transglutaminase mRNA levels in bovine endothelial cells

The pattern of transglutaminase gene expression through the cell cycle was examined by Northern blot analysis using cultured bovine endothelial cells and a cDNA probe. When the cells reached confluency or were arrested in G0/G1 phase by nutrition deprivation, transglutaminase mRNA rose to a very high level; S- and M-phase extracts showed high and low levels, respectively. Subcellular localization studies by sucrose gradient centrifugation and immunostaining demonstrated that the majority of transglutaminase is present in cytosols throughout the cycle. The cell cycle-dependent changes in the transglutaminase mRNA levels strongly support the implicated involvement of the enzyme in cell growth, differentiation, and senescence.

Lectin-dependent inhibition of antigen–antibody reaction: application for measuring α2,6-sialylated glycoforms of transferrin

We developed a high-throughput Enzyme-linked immunosorbent assay (ELISA) for measuring α2,6-sialylated transferrin (Tf), based on inhibition of anti-Tf antibody binding to α2,6-sialylated Tf by a lectin, Sambucus sieboldiana Agglutinin (SSA). The inhibition was not observed with other glycoforms, such as periodate-treated, sialidase-treated and sialidase/galactosidase-treated Tf, suggesting that the assay was glycoform specific. This finding was applied to an automated latex-agglutination immunoassay, using SSA lectin as an inhibitor (SSA-ALI). The concentration of α2,6-sialylated Tf measured by SSA-ALI in human cerebrospinal fluid was correlated with that of ELISA (r2 = 0.8554), previously developed for measuring α2,6-sialylated Tf.