Transglutaminase activity in primary and subcultured rat astroglial cells

Abstract

Transglutaminases, calcium-dependent thiol enzymes, may be involved in cellular growth control and differentiation, having an intracellular regulatory role in some post-translational modifications found in various classes of proteins. In order to elucidate the involvement of this class of enzymes in cellular differentiation processes, we have assayed transglutaminase activity in primary and subcultured rat glial cells. Reduced activity was found from 3rd to 5th passage. In the 5th passage the activity was some 50% of that found in the primary cultures and was not restored by addition of 10 microM retinoic acid. The decrease of TGase activity, observed during serial passages, could represent an early metabolic alteration related to cell dedifferentiation and loss of growth control. In fact, the subcultured cells may have undergone a "disarranged" state, as confirmed by a decrease in GFAP-stained cells and glutamine synthetase activity, respectively, immunocytochemical and biochemical markers of astroglial cells.

Tissue transglutaminase activity is involved in the differentiation of oligodendrocyte precursor cells into myelin‐forming oligodendrocytes during CNS remyelination

“…TG2 was not present in mature, MBP positive OLGs. Together with previous observations that TG2 is involved in differentiation of astrocytes and neurons (Campisi et al, 1992;Tucholski et al, 2001), and a link between TG2 and myelination of Schwann cells was identified (Pittier et al, 2005), our data suggest that TG2 can play an important role in the differentiation of OPCs. To elucidate the functional role of TG2 in OLG differentiation, rat OLGs were treated with TG2 activity inhibitors from various differentiation stages onward.…”

“…TG2 has various functions, amongst which is stimulation of cell differentiation. In this context, TG2 has been shown to stimulate differentiation of a number of cell types, including neurons, astrocytes, and fibroblasts (Balajthy et al, 2006;Campisi et al, 1992;Tucholski et al, 2001). During differentiation of cells including OPCs, activated RhoA GTPase plays an important role in triggering intracellular pathways ultimately leading to essential morphological changes (Czopka et al, 2009).…”

Isolation and characterization of brain-specific transglutaminases from rat

“…Also in the previous studies, TGase activity was present ubiquitously in all the fractions of brain tissue, but at the synaptosomal fraction, the highest activity was detected (Gilad and Varon, 1985, Pastuszko et al, 1986, Korner and Bachrach, 1987, Reichelt and Poulsen, 1992, Campisi et al, 1992.…”

Transglutaminase 2 expression induced by lipopolysaccharide stimulation together with NO synthase induction in cultured astrocytes

“…TG activity has been detected in cultured rat astrocytes as well as neurons (Campisi et al, 1992;Monsonego et al, 1997). Interestingly, TG2 expression in astrocytes is induced by inflammation-associated cytokines such as IL-1β and TNF-α (Monsonego et al, 1997).…”