The apoptosis cascade in human villous trophoblast

ANXA7 regulates trophoblast proliferation and apoptosis in preeclampsia

PROBLEM

Preeclampsia (PE) is a unique gestational disorder leading to maternal and neonatal morbidity and mortality. AnnexinA7 (ANXA7) is a calcium-dependent phospholipid-binding protein that promotes membrane fusion during exocytosis. However, the function of ANXA7 in placental trophoblast is poorly understood. The present study aimed to investigate a possible association between ANXA7 and human trophoblast apoptosis.

METHODS

We collected human placental tissues from patients with PE and normal pregnant women to elucidate the expression level of ANXA7. The ANXA7-knockdown and ANXA7-overexpressing HTR8/SVneo cells were utilized for studying the function of ANXA7 in trophoblast. The proliferation and apoptosis levels of trophoblast were examined with Western blot assay, flow cytometry, Cell Counting Kit-8 assay, and immunohistochemistry.

RESULTS

ANXA7 expression was significantly lower in placentas from patients with PE patients compared with that in from normal pregnant controls. Knockdown of ANXA7 induced cell apoptosis and inhibited cell proliferation in HTR-8 via by downregulating BCL2 protein levels. Overexpression of ANXA7 reduced apoptosis and promoted HTR8 proliferation. Further analyses showed that ANXA7 knockdown inhibited the activation of the JAK1/STAT3 pathway in HTR-8 cells.

CONCLUSION

Our findings revealed a new regulatory pathway of ANXA7/JAK1/STAT3 in trophoblast apoptosis in preeclampsia, suggesting that ANXA7 is a potential therapeutic target for preeclampsia.

Apoptosis and syncytial fusion in human placental trophoblast and skeletal muscle

Skeletal muscle fibers and placental villous trophoblast are the main representatives of syncytia in the human. Both syncytia are derived from fusion of mononucleated stem cells, show a high degree of differentiation, and have lost their generative potency. Consequently, for their growth both depend on fusion of additional stem cells. There is evidence that syncytial fusion is directly or indirectly related to apoptotic events: As early as in the differentiated stages of the mononucleated stem cells, initiation stages of the apoptosis cascade have been observed. After syncytial fusion progression of the cascade is retarded or blocked by a variety of mechanisms. In this review we emphasize the links between apoptosis cascade, differentiation pathways and syncytial fusion. It needs to be elucidated whether these processes simply take place in parallel, both temporally and spatially, or whether there are causal connections between apoptosis cascade and syncytial fusion. Based on recent data obtained for placental villous trophoblast, it is tempting to speculate that early molecular mechanisms of the apoptosis cascade are involved in differentiation and syncytial fusion. Data obtained in skeletal muscles support this assumption and reveal a considerable degree of homology in genesis, maintenance and turnover of both tissues.