... that the suppression of Notch signaling is essential for the establishment of rostro-caudal polarity within a somite and that Mesp2 acts as a novel negative regulator of the Notch signaling pathway. We generated a knock-in mouse in which a dominant-negative form of Rbpj is introduced into the Mesp2 locus. Intriguingly...

... segmented somites are continuously generated, indicating that the NICD on/off state is unnecessary for somite boundary formation. Surprisingly, this mouse also showed a normal rostral-caudal compartment within a somite, conferred by a normal Mesp2 expression pattern with a rostral-caudal gradient...

... for segment border formation is the bHLH transcription factor Mesp2, the expression of which is restricted to the anterior PSM. A gene candidate that is activated by Mesp2 is Epha4 , as its expression pattern resembles Mesp2 and is absent in Mesp2-null embryos. We have analyzed the enhancer region of Epha4...

...Yu Takahashi; Satoshi Kitajima; Tohru Inoue; Jun Kanno; Yumiko Saga Mesp1 and Mesp2 are homologous basic helix-loop-helix (bHLH) transcription factors that are co-expressed in the anterior presomitic mesoderm (PSM) just prior to somite formation. Analysis of possible functional redundancy of Mesp1...

...Yu Takahashi; Tohru Inoue; Achim Gossler; Yumiko Saga Elaborate metamerism in vertebrate somitogenesis is based on segmental gene expression in the anterior presomitic mesoderm (PSM). Notch signal pathways with Notch ligands Dll1 and Dll3, and the transcription factor Mesp2 are implicated...

...Aya Nomura-Kitabayashi; Yu Takahashi; Satoshi Kitajima; Tohru Inoue; Hiroyuki Takeda; Yumiko Saga A bHLH-type transcription factor, Mesp2, plays an essential role in somite segmentation in mice. Zebrafish mespb ( mesp-b ), a putative homologue of mouse Mesp2, is transiently expressed in the rostral...

... in the Notch signalling pathway was altered, including Delta-like3, Hes5 , lunatic fringe ( Lfng ) and Mesp2 . Thus, Ps1-dependent activation of the Notch pathway is essential for caudal half somite development. We observed defects in Notch signalling in both the caudal and rostral region of the presomitic...

...Satoshi Kitajima; Atsuya Takagi; Tohru Inoue; Yumiko Saga ABSTRACT The transcription factors, MesP1 and MesP2, sharing an almost identical bHLH motif, have an overlapping expression pattern during gastrulation and somitogenesis. Inactivation of the Mesp1 gene results in abnormal heart morphogenesis...

... are evenly spaced in time. Bars, 100 μm. In this study, we have isolated two zebrafish cDNAs that encode bHLH transcription factors related to murine MesP1 and MesP2. Recently, Mesp -related genes have been isolated in Xenopus ( Thylacine , Sparrow et al., 1998 ; Mespo ; Joseph...

... laevis paraxial mesoderm bHLH protein Thylacine segmentation somites Notch Delta Mesp2 This work was supported by the Medical Research Council and the British Heart Foundation (D. B. S., S. K., N. T. and T. J. M.) and the NIH (C. K.). W.-C. J. is the holder of a Markey fellowship. We...