Transglutaminase 2 activity promotes membrane resealing after mechanical damage in the lung cancer cell line A549.

Transglutaminase is a Ca2+-dependent enzyme catalyzing protein cross-linking reactions. We investigated the contribution of this enzyme to the resealing of the injured plasma membrane in animal cells, using a lung cancer-derived cell line, A549. After mechanical injury by razor-scratching, the level of membrane resealing was estimated by differential incorporation of dextrans labeled with two distinct fluorescent dyes. The recovery level was decreased in the presence of excess primary amine, as a competitive inhibitor of transglutaminase. We established a cell line that stably expresses shRNA (short hairpin RNA) to specifically inhibit the expression of TGase 2 (tissue-type isozyme of transglutaminase) and confirmed the suppressed resealing level in the cell. Furthermore, additional expression of TGase 2 rescued the ability for membrane resealing. These results show that, after mechanical damage, this enzyme appeared to contribute to membrane resealing.