Mitogen-activated protein kinase (MAPK) pathways mediate embryonic responses to culture medium osmolarity by regulating Aquaporin 3 and 9 expression and localization, as well as embryonic apoptosis.
BACKGROUND
In order to advance the development of culture conditions and increase the potential for supporting normal preimplantation embryo development in vitro, it is critical to define the mechanisms that early embryos utilize to survive in culture. We investigated the mechanisms that embryos employ in response to culture medium osmolarity. We hypothesized that mitogen-activated protein kinase (MAPK) pathways mediate responses to hyperosmotic stress by regulating Aquaporin (AQP) 3 and 9 expression as well as embryonic apoptosis.


METHODS
Real-time reverse transcription and polymerase chain reaction and whole-mount immunofluorescence were used to determine the relative mRNA levels and protein localization patterns of AQP 3 and 9 after hyperosmotic medium treatment.


RESULTS
At 6 and 24 h, a significant increase in Aqp 3 and 9 mRNA was observed in the sucrose hyperosmotic treatment compared with standard medium and glycerol controls. Blockade of MAPK14/11 negated the increase in Aqp 3 and 9 mRNA levels, whereas culture in a MAPK8 blocker did not. Hyperosmotic sucrose treatment significantly increased embryonic apoptosis which was negated in the presence of MAPK8 blocker, but not MAPK14/11 blocker.


CONCLUSIONS
MAPK14/11 activation is a component of the rapid adaptive stress response mechanism that includes the effects of AQP mRNA expression and protein localization, whereas the MAPK8 pathway is a regulator of apoptosis.
Bell
Christine E
CE
Department of Obstetrics and Gynaecology, The University of Western Ontario, London, Ontario, Canada.
Larivière
Nathalie M K
NM
Watson
Patricia H
PH
Watson
Andrew J
AJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051400:Aquaporin 3 / Q000235:genetics / Q000378:metabolism*; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001755:Blastocyst / Q000502:physiology*; D003470:Culture Media / Q000494:pharmacology; D046149:Embryo Culture Techniques; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005990:Glycerol / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D051379:Mice; D048290:Mitogen-Activated Protein Kinase 11 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048308:Mitogen-Activated Protein Kinase 14 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009994:Osmolar Concentration; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000502:physiology*
C496028:Aqp3 protein, mouse; C491638:Aqp9 protein, mouse; D020346:Aquaporins; D003470:Culture Media; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D051400:Aquaporin 3; D013395:Sucrose; D048290:Mitogen-Activated Protein Kinase 11; D048308:Mitogen-Activated Protein Kinase 14; D048055:Mitogen-Activated Protein Kinase 8; D005990:Glycerol