Differential expression of the metalloproteinase MMP3 and the alpha5 integrin subunit in human myometrium at labour.

Extensive tissue remodelling occurs in the human myometrium before, during and after parturition. The aim of this study was to investigate the expression of two tissue remodelling molecules, matrix metalloproteinase 3 (MMP3) and alpha5 integrin (ITGA5) subunit in human myometrium, during pregnancy and labour. mRNA and protein were isolated from human pregnant labouring and non-labouring myometrial tissue, and also from human primary uterine smooth muscle cells (SMCs). Semi-quantitative RT-PCR, real-time fluorescence RT-PCR and western blotting were subsequently performed to determine the expression levels of MMP3 and ITGA5 in the myometrial tissues during pregnancy and labour, and in the primary uterine SMCs. The expression of MMP3 and ITGA5 mRNA and protein are reported for the first time during pregnancy and labour in human myometrium. Furthermore, a significant increase in expression of MMP3 mRNA (41-fold, P = 0.001), and a significant decrease in ITGA5 mRNA expression (4-fold, P < 0.001) at labour, were observed. Protein expression of these two molecules was also altered at labour, pro-MMP3 protein expression significantly increased while ITGA5 protein expression decreased, with labour onset. Expression of these molecules was also observed in primary cultured human uterine SMCs. The differential expression of these two tissue remodelling molecules at labour and their detection in uterine SMCs highlights their potential importance in myometrial function during pregnancy, labour and post-partum.