title: Inhibition of RHO-ROCK signaling enhances ICM and suppresses TE characteristics through activation of Hippo signaling in the mouse blastocyst.
abstract: Specification of the trophectoderm (TE) and inner cell mass (ICM) lineages in the mouse blastocyst correlates with cell position, as TE derives from outer cells whereas ICM from inner cells. Differences in position are reflected by cell polarization and Hippo signaling. Only in outer cells, the apical-basal cell polarity is established, and Hippo signaling is inhibited in such a manner that LATS1 and 2 (LATS1/2) kinases are prevented from phosphorylating YAP, a key transcriptional co-activator of the TE-specifying gene Cdx2. However, the molecular mechanisms that regulate these events are not fully understood. Here, we showed that inhibition of RHO-ROCK signaling enhances ICM and suppresses TE characteristics through activation of Hippo signaling and disruption of apical-basal polarity. Embryos treated with ROCK inhibitor Y-27632 exhibited elevated expression of ICM marker NANOG and reduced expression of CDX2 at the blastocyst stage. Y-27632-treated embryos failed to accumulate YAP in the nucleus, although it was rescued by concomitant inhibition of LATS1/2. Segregation between apical and basal polarity regulators, namely PARD6B, PRKCZ, SCRIB, and LLGL1, was dampened by Y-27632 treatment, whereas some of the polarization events at the late 8-cell stage such as compaction and apical localization of p-ERM and tyrosinated tubulin occurred normally. Similar abnormalities of Hippo signaling and apical-basal polarization were also observed in embryos that were treated with RHO GTPases inhibitor. These results suggest that RHO-ROCK signaling plays an essential role in regulating Hippo signaling and cell polarization to enable proper specification of the ICM and TE lineages.
authors.affiliation: Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA.
authors.forename: Kanako
authors.initials: K
authors.lastname: Kono
authors.affiliation: Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA.
authors.forename: Dana Ann A
authors.initials: DA
authors.lastname: Tamashiro
authors.affiliation: Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA. Electronic address: vernadet@hawaii.edu.
authors.forename: Vernadeth B
authors.initials: VB
authors.lastname: Alarcon
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis; D000577:Amides / Q000494:pharmacology; D000818:Animals; D053624:Blastocyst Inner Cell Mass / Q000378:metabolism*; D000071616:CDX2 Transcription Factor; D018797:Cell Cycle Proteins; D002454:Cell Differentiation; D019070:Cell Lineage; D016764:Cell Polarity / Q000502:physiology; D003598:Cytoskeletal Proteins; D004475:Ectoderm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D000090683:Hippo Signaling Pathway; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D000071317:Nanog Homeobox Protein; D010750:Phosphoproteins / Q000096:biosynthesis; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D000091102:YAP-Signaling Proteins; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000099221:Protein Kinase C zeta
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000577:Amides; D000071616:CDX2 Transcription Factor; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D000071317:Nanog Homeobox Protein; D010750:Phosphoproteins; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D034741:RNA, Small Interfering; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000091102:YAP-Signaling Proteins; D020741:rho GTP-Binding Proteins; D054460:rho-Associated Kinases; D000099221:Protein Kinase C zeta; C487514:Cdx2 protein, mouse; C082939:Llgl1 protein, mouse; C475540:Nanog protein, mouse; C486223:Yap1 protein, mouse; C508433:scrib protein, mouse; C108830:Y 27632; C490501:Lats1 protein, mouse; C522633:LATS2 protein, mouse
keywords: CDX2; Cell lineage; Cell polarity; Inner cell mass; Trophectoderm; YAP