Development

Pregnancy Can Be Stressful

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Science  09 Oct 2009:
Vol. 326, Issue 5950, pp. 206-207
DOI: 10.1126/science.326_206d

When cells and tissues experience environmental stress, the endoplasmic reticulum (ER)—a membrane-bounded intracellular compartment—accumulates incorrectly folded proteins. The inositol requiring enzyme–1 (IRE1) mediates an unfolding protein response (UPR) that relieves ER stress by activating the expression of genes that participate in protein quality control.

Prior work has documented embryonic lethality in mice after inactivation of IRE1. Using in vivo imaging and knockout mice, Iwawaki et al. show that IRE1 functions in the placenta after ER stress induction. In mice lacking IRE1, vascular endothelial growth factor–A was reduced and angiogenic defects were seen in the labyrinth layer of the placenta, consistent with diminished transport of oxygen and other nutrients. Therefore, IRE1 functions, at least in part, in extraembryonic tissues during early development.

Proc. Natl. Acad. Sci. U.S.A. 106, 10.1073/pnas.0903775106 (2009).

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