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17 February 2017 Acute cell volume regulation by Janus kinase 2-mediated sodium/hydrogen exchange activation develops at the late one-cell stage in mouse preimplantation embryos
Baozeng Xu, Chenxi Zhou, Megan Meredith, Jay M. Baltz
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Abstract

Early preimplantation embryos are extremely sensitive to dysregulation of cell volume, which can lead to developmental arrest. It was previously shown that mouse embryos at the two-cell stage respond to a cell volume decrease by quickly activating Na+/H+ exchange via a signaling mechanism that involves the tyrosine kinase Janus kinase 2 (JAK2). However, it was not known whether this mechanism is active at the one-cell stage, when embryos are most sensitive to perturbed cell volume. Na+/H+ exchanger activity elicited by an induced cell volume decrease was significantly lower at the mid one-cell stage than at the late one-cell stage or during the two-cell stage. This activity could be completely blocked by the broad specificity tyrosine kinase inhibitor genistein at either stage, but only at the two-cell stagewas there a substantial component of activity that was sensitive to low concentrations of the JAK2-selective inhibitors TG101348 or ruxolitinib. Western blots to detect active JAK2 phosphorylated on tyrosine Y1007/8 revealed that JAK2 became substantially phosphorylated in response to a cell volume decrease at the mid two-cell, but not mid one-cell stage. Such cell volume decrease-induced JAK2 phosphorylation appeared by the late one-cell stage. At least in part this appears to be due to an increase in total JAK2 protein at the late one-cell stage. Furthermore, TG101348 impaired maintenance of cell volume at the two-cell, but not mid one-cell, stages. Thus, cell volume homeostasis requiring Na+/H+ exchange signaled by JAK2 first becomes prominent during mouse embryonic development at the late one-cell stage.

Summary Sentence

The major mechanism of acute recovery from decreased cell volume in somatic cells, activation of sodium hydrogen exchanger NHE1 (SLC9A1) by the tyrosine kinase Janus kinase 2 (JAK2), first develops at the late one-cell stage of mouse embryo.

© The Authors 2017. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Baozeng Xu, Chenxi Zhou, Megan Meredith, and Jay M. Baltz "Acute cell volume regulation by Janus kinase 2-mediated sodium/hydrogen exchange activation develops at the late one-cell stage in mouse preimplantation embryos," Biology of Reproduction 96(3), 542-550, (17 February 2017). https://doi.org/10.1095/biolreprod.116.143974
Received: 8 March 2016; Accepted: 2 February 2017; Published: 17 February 2017
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