Elsevier

Developmental Biology

Volume 289, Issue 2, 15 January 2006, Pages 406-419
Developmental Biology

Na+/K+-ATPase regulates tight junction formation and function during mouse preimplantation development

https://doi.org/10.1016/j.ydbio.2005.11.004Get rights and content
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Abstract

Research applied to the early embryo is required to effectively treat human infertility and to understand the primary mechanisms controlling development to the blastocyst stage. The present study investigated whether the Na+/K+-ATPase regulates tight junction formation and function during blastocyst formation. To investigate this hypothesis, three experimental series were conducted. The first experiments defined the optimal dose and treatment time intervals for ouabain (a potent and specific inhibitor of the Na+/K+-ATPase) treatment. The results demonstrated that mouse embryos maintained a normal development to the blastocyst stage following a 6-h ouabain treatment. The second experiments investigated the effects of ouabain treatment on the distribution of ZO-1 and occludin (tight junction associated proteins). Ouabain treatment (up to 6 h) or culture in K+-free medium (up to 6 h) resulted in the appearance of a discontinuous ZO-1 protein distribution and a loss of occludin immunofluorescence. The third set of experiments examined the influence of ouabain treatment on tight junction function. Ouabain treatment or culture in K+-free medium affected tight junction permeability as indicated by an increase in the proportion of treated embryos accumulating both 4 kDa and 40 kDa fluorescein isothiocyanate (FITC)-dextran into their blastocyst cavities. The results indicate that the Na+/K+-ATPase is a potent regulator of tight junction formation and function during mouse preimplantation development.

Keywords

Ion transport
Cell junctions
In vitro fertilization
Cell polarity
Trophectoderm

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