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  • Title: Dynamic alterations in integrin α4 expression by hypoxia are involved in trophoblast invasion during early implantation.
    Author: Na KH, Lee HJ, Choi JH, Eun JW, Nam SW, Yoon TK, Kim GJ.
    Journal: J Cell Biochem; 2012 Feb; 113(2):685-94. PubMed ID: 21976114.
    Abstract:
    Implantation of the blastocyst into the maternal endometrium is mediated by a population of well-differentiated primary cells of the placenta known as trophoblasts, which grow in an invasive and destructive fashion similar to tumor cells. Interactions between the endometrium and trophoblasts are regulated by a coordinated interplay of extracellular matrix (ECM) proteins secreted by the invading extravillous trophoblasts. Integrins act as adhesion receptors and mediate both cell-ECM and cell-cell interactions. However, the correlation between integrin expression and trophoblast invasion under hypoxia is unclear. Here, we analyzed the expression of integrins in HTR-8/SVneo trophoblast cells exposed to hypoxic conditions in order to demonstrate an association between invasion activity and integrin expression in trophoblasts. Trophoblasts were examined by microarray analysis, RT-PCR, western blotting, and zymography after 1% hypoxic treatment, and cell invasion was estimated. The dynamic expression of integrins and human matrix metalloproteinases (MMPs) was observed under hypoxic conditions. The invasiveness of trophoblasts cultured under 1% hypoxic conditions was significantly greater than that of trophoblasts cultured under normoxic conditions through alterations in MMP-2 and -9 (P < 0.05). Notably, integrin α4 expression during early hypoxia was negatively regulated by hypoxia-inducible factor-1alpha (HIF-1alpha) expression in trophoblasts. The downregulation of integrin α4 expression by siRNA treatment controlled trophoblast invasion activity (P < 0.05). Taken together, we suggest that dynamic changes in integrins, including those in integrin α4 expression by hypoxia, play a regulatory role in trophoblast invasion. These findings expand our understanding of the potential roles of integrin α4 in implantation.
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