Anthrax toxin receptor 2 promotes human uterine smooth muscle cell viability, migration and contractility

ObjectivePreviously we demonstrated anthrax toxin receptor 2 knockout (Antxr2−/−) mice are fertile but fail to deliver their pups at term. This parturition defect is associated with overaccumulation of extracellular matrix proteins and decreased myometrial cell content in the uterus. Myometrial cell loss in Antxr2−/− uterine tissue prompted us to evaluate if ANTXR2 is essential for human uterine smooth muscle cell viability and function.Study DesignWe subjected human uterine smooth muscle cell to lentiviral-mediated knock down or retroviral-mediated overexpression of ANTXR2. Flow cytometry confirmed lentiviral-mediated knock down or retroviral-mediated overexpression in cell lines vs control. Cell behavior and function in control, lentiviral-mediated knock down and retroviral-mediated overexpression cells were evaluated for apoptosis via TUNEL assay, migration via Boyden chamber assay and with oxytocin-mediated collagen contraction assays. Matrix metalloproteinase activity was evaluated using gelatin zymography. Cell lines and samples were run in duplicate. Student t test was used for statistical analysis.ResultsANTXR2 is expressed by human uterine smooth muscle cell. Human uterine smooth muscle cell-lentiviral-mediated knock down cells exhibited increased apoptosis (P < .05) and decreased migration (P < .05), although human uterine smooth muscle cell-retroviral-mediated overexpression cells exhibited no change in apoptosis (P = .91) and increased migration (P = .05) vs control. Human uterine smooth muscle cell-lentiviral-mediated knock down cells contracted significantly less than control, although human uterine smooth muscle cell-retroviral-mediated overexpression cells showed no difference in contractility vs control. Matrix metalloproteinase activity 2 activity appeared slightly decreased in human uterine smooth muscle cell-lentiviral-mediated knock down cells and increased in human uterine smooth muscle cell-retroviral-mediated overexpression cells vs control.ConclusionANTXR2 is expressed by human uterine smooth muscle cell and appears important for normal human uterine smooth muscle cell viability, migration and contractility. Further studies are needed to delineate if ANTXR2 is important for normal and abnormal labor patterns.