title: p38 mitogen-activated protein kinase (MAPK) first regulates filamentous actin at the 8-16-cell stage during preimplantation development.
abstract: BACKGROUND
  The MAPK (mitogen-activated protein kinase) superfamily of proteins consists of four separate signalling cascades: the c-Jun N-terminal kinase or stress-activated protein kinases (JNK/SAPK); the ERKs (extracellular-signal-regulated kinases); the ERK5 or big MAPK1; and the p38 MAPK group of protein kinases, all of which are highly conserved. To date, our studies have focused on defining the role of the p38 MAPK pathway during preimplantation development. p38 MAPK regulates actin filament formation through the downstream kinases MAPKAPK2/3 (MAPK-activated protein kinase 2/3) or MAPKAPK5 [PRAK (p38 regulated/activated kinase)] and subsequently through HSP25/27 (heat-shock protein 25/27). We recently reported that 2-cell-stage murine embryos treated with cytokine-suppressive anti-inflammatory drugs (CSAIDtrade mark; SB203580 and SB220025) display a reversible blockade of development at the 8-16-cell stage, indicating that p38 (MAPK) activity is required to complete murine preimplantation development. In the present study, we have investigated the stage-specific action and role of p38 MAPK in regulating filamentous actin during murine preimplantation development.
  
  
  RESULTS
  Treatment of 8-cell-stage embryos with SB203580 and SB220025 (CSAIDtrade mark) resulted in a blockade of preimplantation development, loss of rhodamine phalloidin fluorescence, MK-p (phosphorylated MAPKAPK2/3), HSP-p (phosphorylated HSP25/27) and a redistribution of alpha-catenin immunofluorescence by 12 h of treatment. In contrast, treatment of 2- and 4-cell-stage embryos with CSAIDtrade mark drugs resulted in a loss of MK-p and HSP-p, but did not result in a loss of rhodamine phalloidin fluorescence. All these effects of p38 MAPK inhibition were reversed upon removal of the inhibitor, and development resumed in a delayed but normal manner to the blastocyst stage. Treatment of 8-cell embryos with PD098059 (ERK pathway inhibitor) did not affect development or fluorescence of MK-p, HSP-p or rhodamine phalloidin.
  
  
  CONCLUSIONS
  Murine preimplantation development becomes dependent on p38 MAPK at the 8-16-cell stage, which corresponds to the stage when p38 MAPK first regulates filamentous actin during early development.
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada N6A 5C1.
authors.forename: Andrew J M
authors.initials: AJ
authors.lastname: Paliga
authors.forename: David R
authors.initials: DR
authors.lastname: Natale
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Watson
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000378:metabolism*; D015820:Cadherins; D015815:Cell Adhesion Molecules / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D047108:Embryonic Development / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000502:physiology*; D009028:Morula / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D015398:Signal Transduction; D013997:Time Factors; D051178:alpha Catenin; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D000199:Actins; D015820:Cadherins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D006360:Heat-Shock Proteins; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D048052:Mitogen-Activated Protein Kinase 3; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D011743:Pyrimidines; D051178:alpha Catenin; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C489083:Cdh2 protein, mouse; C495272:Ctnna1 protein, mouse; C110631:SB 220025; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one