Transglutaminase activity during the differentiation of macrophages

Abstract

Summary Transglutaminase (R-glutaminyl-peptide:amine γ-glutamyltransferase, E.C. 2,3,2,13) activity during the differentiation of murine leukemia cell lines (M1 cells) was investigated. Ml cells contained a significant transglutaminase activity of the tissue type. During the course of differentiation into mature macrophage-like M1 + cells induced with a protein inducer, the enzymatic activity was stimulated more than ten times as much as in the original undifferentiated Ml − cells. A remarkable enhancement of enzymatic activity was also observed when lipopolysaccharide was utilized as an inducer of differentiation. The enzymatic activity of undifferentiated M1 − cells was eluted at the region of M.W. ca. 80,000 as a single and symmetrical peak on Sepharose 4B column chromatography. By contrast, most of the activity in differentiated Ml + cells was eluted at the void volume under the same condition, though some activities were eluted at the same region as in Ml − cells. These data suggest that most of transglutaminase activity exists in the form of a high-molecular-weight complex with some cellular components in differentiated cells. The possible physiological significance of the enzyme in macrophage functions was discussed.