Anthrax Toxin Receptor 2 Functions in ECM Homeostasis of the Murine Reproductive Tract and Promotes MMP Activity

Abstract

Anthrax Toxin Receptor proteins function as receptors for anthrax toxin, however physiological activity remains unclear. To evaluate the biological role of Antxr2, we generated Antxr2−/− mice. Antxr2−/− mice were viable, however Antxr2 is required for parturition in young females and for preserving fertility in older female mice. Histological analysis of the uterus and cervix revealed aberrant deposition of extracellular matrix proteins such as type I collagen, type VI collagen and fibronectin. A marked disruption of both the circular and longitudinal myometrial cell layers was evident in Antxr2−/− mice. These changes progressed as the mice aged, resulting in a thickened, collagen dense, acellular stroma and the disappearance of normal uterine architecture. To investigate the molecular mechanism underlying the uterine fibrosis we performed immunoblotting for MMP2 using uterine lysates and zymography using conditioned medium from Antxr2−/− mouse embryonic fibroblasts and found reduced levels of activated MMP2 in both. This prompted us to investigate MT1-MMP status, as MMP2 processing is regulated by MT1-MMP. We found MT1-MMP activity, as measured by MMP2 processing and activation, was enhanced by expression of either ANTXR1 or ANTXR2. We identified an ANTXR2/MT1-MMP complex and demonstrated that MT1-MMP activity is dependent on ANTXR2 expression levels in cells. Thus, we have discovered that ANTXR1 and ANTXR2 function as positive regulators of MT1-MMP activity.

Targeted Silencing of Anthrax Toxin Receptors Protects against Anthrax Toxins

“…We would also need to evaluate safety in vivo because ANTXRs are involved in angiogenesis and ECM homeostasis (9). However, it is known that Tem8-or Cmg2-null or knock-out mice are viable, develop normally, and survive into adulthood (19,(43)(44)(45). Phenotypically, the main defect in these mice is excessive ECM protein deposition (19,43).…”

“…However, it is known that Tem8-or Cmg2-null or knock-out mice are viable, develop normally, and survive into adulthood (19,(43)(44)(45). Phenotypically, the main defect in these mice is excessive ECM protein deposition (19,43). Aberrant ECM deposition in the cervix and uterus of females has been associated with fertility defects observed in the females of null or knock-out mice (19).…”

“…Phenotypically, the main defect in these mice is excessive ECM protein deposition (19,43). Aberrant ECM deposition in the cervix and uterus of females has been associated with fertility defects observed in the females of null or knock-out mice (19). Thus, a possible side effect of silencing ANTXRs would be increased ECM deposition for the transient period in which these receptors are silenced.…”

Overexpression of Endogenous TIMP-2 Increases the Proliferation of BeWo Choriocarcinoma Cells Through the MAPK-Signaling Pathway

“…[22][23][24] In our study, under the biologically relevant condition of TIMP-2, only BeWo cells increased proliferation but not HT-1080 or 293 T cell. This showed the unique characteristic of BeWo cell in terms of the way to respond to TIMP-2.…”

“…The HEK293T has been widely used in studies that involved gene transfection, [22][23][24] and HT-1080 has been used in studies to evaluate the effect of TIMP-2 on cell proliferation. 11,21 Therefore, we used these cell lines as controls to compare the characteristic of BeWo cells in terms of response to TIMP-2 under the biologically relevant condition of TIMP-2.…”