Present and Active: Transglutaminases in the Virgin Rat Uterus and Cervix

Transglutaminases are a family of enzymes that are known for their protein cross-linking abilities. Transglutaminases have been investigated very little in female reproductive tissues. We hypothesized that transglutaminase proteins were present and active in the virgin rat uterus and cervix. In both tissues, real time RT-PCR identified transglutaminase 1, 2, 3, and 4 mRNA, and immunohistochemistry determined the presence of transglutaminase 1, 2, 3, and 4 proteins. Transglutaminase 1, 2 and 3 were active in the virgin rat uterus, and transglutaminase 1 and 3 were active in the virgin rat cervix, identified in situ by isoform-specific FITC-labeled substrates. Transglutaminase 2 was active in the virgin rat uterus but absent in the cervix. The transglutaminase inhibitor cystamine (1 mM) reduced maximal agonist-induced isometric contraction in the uterus, but not the cervix. This study provides new knowledge of active transglutaminase isozymes in female reproductive tissues.