Anti-Apoptotic Effect of Apelin in Human Placenta: Studies on BeWo Cells and Villous Explants from Third-Trimester Human Pregnancy.

Ewa Mlyczyńska,Małgorzata Myszka,Monika Dawid,Patrycja Kurowska,Marta Bałajewicz-Nowak,Paweł Kowalczyk,Agnieszka Rak,Tomasz Milewicz

doi:10.3390/ijms22052760

Abstract

Previously, we demonstrated the expression of apelin and G-protein-coupled receptor APJ in human placenta cell lines as well as its direct action on placenta cell proliferation and endocrinology. The objective of this study was to examine the effect of apelin on placenta apoptosis in BeWo cells and villous explants from the human third trimester of pregnancy. The BeWo cells and villous explants were incubated with apelin (2 and 20 ng/mL) alone or with staurosporine for 24 to 72 h. First, we analysed the dose- and time-dependent effect of apelin on the expression of apoptotic factors on the mRNA level by real-time PCR and on the protein level using Western blot. Next, we checked caspase 3 and 7 activity by Caspase-Glo 3/7, DNA fragmentation by the Cell Death Detection ELISA kit and oxygen consumption by the MitoXpress-Xtra Oxygen Consumption assay. We found that apelin increased the expression of pro-survival and decreased proapoptotic factors on mRNA and protein levels in both BeWo cells and villous explants. Additionally, apelin inhibited caspase 3 and 7 activity and DNA fragmentation in staurosporine-induced apoptosis as also attenuated oxidative stress by increasing extracellular oxygen consumption. The antiapoptotic effect of apelin in BeWo cells was mediated by the APJ receptor and mitogen-activated protein kinase (ERK1/2/MAP3/1) and protein kinase B (AKT). The obtained results showed the antiapoptotic effect of apelin on trophoblast cells, suggesting its participation in the development of the placenta.

Highlights

The placenta is a transient organ whose main function is to ensure optimal conditions for foetal development; it provides the nutrients and oxygen from maternal circulations to the foetus and is the place of the production of numerous hormones necessary for the maintenance of the pregnancy
In the external pathway, apoptosisinducing factors act by binding to death receptors, such as tumour necrosis factor receptor (TNFR), or nucleotide-binding oligomerisation domain containing protein 1 (NOD1) and activate receptor domains such as caspase and RIP adapter with death domain (CRADD)
We observed that apelin in placenta BeWo cells modulates, in a dose-dependent manner, the gene expression of multiple factors which are involved in the regulation of programmed cell death

Summary

Introduction

The placenta is a transient organ whose main function is to ensure optimal conditions for foetal development; it provides the nutrients and oxygen from maternal circulations to the foetus and is the place of the production of numerous hormones necessary for the maintenance of the pregnancy. The development of such an organ must occur within just a few weeks. Many reports have suggested that apoptosis in the placenta is a natural physiological phenomenon It occurs during syncytial fusion, throughout the

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