Anti-ACVR2A monoclonal antibody, clone NN1169-7K27

Activin (ACV) A induces various cellular functions via activin receptor type 2 (ACVR2A/2B)-activin receptor-like kinase (ALK) 4-Smad 2/3 pathway. Although the production of ACVA is indicated in bovine oviducts, its role on the oviduct is unclear. Oviductal isthmus needs to change its function rapidly at perifertilization, however, the mechanism is unknown. This study was aimed to clarify the role of ACVA in the morphological changes of oviductal isthmus in cows. First, mRNA expressions of INHBA (ACVA component) and its receptors (ALK4, ACVR2A and ACVR2B) in the isthmic tissues were examined throughout the estrous cycle. INHBA was the highest, however, ACVR2A was the lowest on the day of ovulation, suggesting reduced ACV signal transduction in the isthmus just after ovulation. Proteins of ACVRs and Smad2/3 were clearly detected in the cultured epithelial cells. It is known that ACVA regulates cellular apoptosis. Our data showed that the number of cleaved caspase-3-positive epithelial cells was largest at 2-3 days after ovulation in the isthmus. Interestingly, our study demonstrated that follistatin (ACV/TGFB/BMP inhibitor) significantly decreased the BCL2/BAX ratio in the cultured isthmic epithelial cells. To clarify which ALK pathway is involved in the regulation of BCL2/BAX ratio, the effects of SB431542 (ACV signaling (ALK4) and TGFB signaling (ALK5) inhibitor), SB525334 (ALK5 inhibitor) and LDN193189 (BMP signaling (ALK2/3) inhibitor) were investigated in the next study. The results showed that only SB431542 significantly decreased BCL2/BAX and the others had no effects. These results suggest that decreased ACVA-ACVR2A-ALK4 signal at the post-ovulation induces cyclic apoptosis of isthmic epithelial cells in bovine oviducts. (C) 2020 Elsevier Inc. All rights reserved.

Bone morphogenetic protein (BMP) 2 and activin A belong to the TGF-beta superfamily and are highly expressed in human endometrium and placenta. Studies have demonstrated that activin A and BMP2 play essential roles in the process of early embryo implantation by promoting human trophoblast cell invasion. However, whether activin A production can be regulated by BMP2 in human trophoblast cells remains unknown. The aim of our study was to determine the effects of BMP2 on activin A production and its role in human trophoblast invasion. Primary human extravillous trophoblast (EVT) cells were used as study models. BMP2 treatment significantly increased inhibin beta A (INHBA) mRNA levels and activin A production without altering inhibin alpha and inhibin beta B levels. BMP2-induced EVT cell invasion was attenuated by knockdown of INHBA. The increased INHBA transcription and activin A production by BMP2 were blocked by the type I receptor activin receptor (ACVR)-like kinase 2 (ALK2) and activin receptor-like kinase 3 (ALK3) inhibitor dorsomorphin homolog 1 (DMH-1). BMP2-induced INHBA upregulation was also inhibited by knockdown of type I receptor ALK3 or combined knockdown of type II receptors for BMP2 (BMPR2) and ACVR2A. Whereas BMP2 initiated both canonical SMAD1/5/8 and noncanonical SMAD2/3 signaling, only knockdown of SMAD4, but not SMAD2 and SMAD3, abolished the effects of BMP2 on INHBA. Our results show that BMP2 increases human trophoblast invasion by upregulating INHBA and activin A production via ALK3-BMPR2/ACVR2A-SMAD1/5/8-SMAD4 signaling.