Mouse preimplantation embryo responses to culture medium osmolarity include increased expression of CCM2 and p38 MAPK activation.
BACKGROUND
Mechanisms that confer an ability to respond positively to environmental osmolarity are fundamental to ensuring embryo survival during the preimplantation period. Activation of p38 mitogen-activated protein kinase (MAPK) occurs following exposure to hyperosmotic treatment. Recently, a novel scaffolding protein called Osmosensing Scaffold for MEKK3 (OSM) was linked to p38 MAPK activation in response to sorbitol-induced hypertonicity. The human ortholog of OSM is cerebral cavernous malformation 2 (CCM2). The present study was conducted to investigate whether CCM2 is expressed during mouse preimplantation development and to determine whether this scaffolding protein is associated with p38 MAPK activation following exposure of preimplantation embryos to hyperosmotic environments.


RESULTS
Our results indicate that Ccm2 along with upstream p38 MAPK pathway constituents (Map3k3, Map2k3, Map2k6, and Map2k4) are expressed throughout mouse preimplantation development. CCM2, MAP3K3 and the phosphorylated forms of MAP2K3/MAP2K6 and MAP2K4 were also detected throughout preimplantation development. Embryo culture in hyperosmotic media increased p38 MAPK activity in conjunction with elevated CCM2 levels.


CONCLUSIONS
These results define the expression of upstream activators of p38 MAPK during preimplantation development and indicate that embryo responses to hyperosmotic environments include elevation of CCM2 and activation of p38 MAPK.
Fong
Barry
B
Department of Physiology and Pharmacology, The University of Western Ontario London, Ontario, Canada. bfong@uwo.ca <bfong@uwo.ca>
Watson
Patricia H
PH
Watson
Andrew J
AJ
D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media; D004789:Enzyme Activation; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D051379:Mice; D008840:Microfilament Proteins / Q000096:biosynthesis* / Q000235:genetics; D018613:Microscopy, Confocal; D009994:Osmolar Concentration; D010766:Phosphorylation; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D003470:Culture Media; D008840:Microfilament Proteins; C480498:osmosensing scaffold for MEKK3 protein, mouse; D048051:p38 Mitogen-Activated Protein Kinases