PT - JOURNAL ARTICLE AU - Jin Yan AU - Barbara F. Hales TI - p38 and c-Jun N-Terminal Kinase Mitogen-Activated Protein Kinase Signaling Pathways Play Distinct Roles in the Response of Organogenesis-Stage Embryos to a Teratogen AID - 10.1124/jpet.108.139907 DP - 2008 Sep 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 764--772 VI - 326 IP - 3 4099 - http://jpet.aspetjournals.org/content/326/3/764.short 4100 - http://jpet.aspetjournals.org/content/326/3/764.full SO - J Pharmacol Exp Ther2008 Sep 01; 326 AB - Mitogen-activated protein kinase (MAPK) signaling plays an important role during embryo development. We hypothesize that MAPK activation is a determinant of the fate of organogenesis-stage embryos exposed to insult. To test this hypothesis, CD1 mice were exposed to a model teratogen, hydroxyurea, on gestational day 9. Hydroxyurea exposure triggered a dramatic, transient increase in the activation of p38 MAPKs and c-Jun N-terminal kinases (JNKs) in embryos, without activating extracellular signal-regulated kinases 1 and 2. Selectively blocking p38 MAPKs with 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580) enhanced hydroxyurea-induced fetal mortality without affecting growth retardation or the incidence of deformities among surviving fetuses. In contrast, selectively blocking JNKs with JNK peptide inhibitor 1, l-stereoisomer did not affect hydroxyurea-induced fetal death but increased the incidence of the hindlimb defects observed. Thus, p38 MAPKs and JNKs play distinct roles in protecting the conceptus against insult. Pharmacological inhibition of teratogen exposure induced MAPK activation has adverse consequences on the embryo. The American Society for Pharmacology and Experimental Therapeutics