Tbx6-mediated Notch signaling controls somite-specific Mesp2 expression

Amphibians have been used for over a century as experimental animals. In the field of developmental biology in particular, much knowledge has been accumulated from studies on amphibians, mainly because they are easy to observe and handle. Xenopus laevis is one of the most intensely investigated amphibians in developmental biology at the molecular level. Thus, Xenopus is highly suitable for studies on the mechanisms of organ differentiation from not only a single fertilized egg, as in normal development, but also from undifferentiated cells, as in the case of in vitro organogenesis. Based on the established in vitro organogenesis methods, we have identified many genes that are indispensable for normal development in various organs. These experimental systems are useful for investigations of embryonic development and for advancing regenerative medicine. Developmental Dynamics 238:1309 -1320, 2009.

Section: Identification and Characterization Of Novel Somitogenesis-rmentioning

confidence: 99%

In vitro organogenesis from undifferentiated cells in Xenopus

Asashima

Ito

Chan

et al. 2009

“…Thus, Snail2 appears to have a second role in controlling the morphogenetic processes associated with epithelialization (Dale et al, 2006). Transcriptional regulation of Mesp2 can also occur by means of the T-box transcription factor, Tbx6 (Yasuhiko et al, 2006).…”

Section: Targeting Somite Epithelializationmentioning

confidence: 99%

From segment to somite: Segmentation to epithelialization analyzed within quantitative frameworks

Kulesa

Schnell

Rudloff

et al. 2007

One of the most visually striking patterns in the early developing embryo is somite segmentation. Somites form as repeated, periodic structures in pairs along nearly the entire caudal vertebrate axis. The morphological process involves short-and long-range signals that drive cell rearrangements and cell shaping to create discrete, epithelialized segments. Key to developing novel strategies to prevent somite birth defects that involve axial bone and skeletal muscle development is understanding how the molecular choreography is coordinated across multiple spatial scales and in a repeating temporal manner. Mathematical models have emerged as useful tools to integrate spatiotemporal data and simulate model mechanisms to provide unique insights into somite pattern formation. In this short review, we present two quantitative frameworks that address the morphogenesis from segment to somite and discuss recent data of segmentation and epithelialization.

“…Hence, these genes are not involved in the events in the posterior PSM and, thus, have functions that are independent of the segmentation clock. However, the expression of Mesp2 is dependent upon the clock, this gene operates within the Notch signaling cascade Yasuhiko et al, 2006), and the corresponding knockout mouse embryo had lost both the segmental borders and RC polarity (Saga et al, 1997). In addition, Mesp1 has a compensatory function of Mesp2 (Saga, 1998;Takahashi et al, 2007), although the single knockout of Mesp1 does not show segmental defects (Saga et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…The main issue of how the segmental borders are formed is, thus, likely to entail the mechanisms by which the Mesp2 expression domain is restricted in the PSM. Recent enhancer studies strongly indicate that Tbx6 and Notch signaling are required for the induction of Mesp2 (Yasuhiko et al, 2006) and that the expression of this gene is also regulated by a negative feedback loop. In this review, I summarize the significance of the Mesp transcription factors during somitogenesis by focusing on the function and regulation of Mesp2.…”

Section: Introductionmentioning

confidence: 99%

Segmental border is defined by the key transcription factor Mesp2, by means of the suppression of notch activity

Saga

2007

Self Cite

Elaborate somite patterning is based upon dynamic gene regulation within the presomitic mesoderm (PSM), which is derived from the primitive streak and tail bud in the later stage mouse embryo. The Notch signaling pathway and its regulators are major components of most of the events required for temporally and spatially coordinated somite formation. The PSM can be subdivided into at least two domains, based upon transcriptional regulation and gene function. In the posterior PSM, the basic helix-loop-helix (bHLH) protein Hes7 plays a central role in generating a traveling wave of gene expression by negatively regulating the transcription of its target genes. This in turn may define the somite spacing and future segmental units. In the anterior PSM, cells begin to form segmental patterning by acquiring rostral or caudal identities of somite primordia and by defining the segmental border, which must be coupled with the segmentation clock. The link between the clock and segmental border formation is of fundamental importance during somitogenesis. During this process, Mesp2, another basic HLH protein, plays a critical role in the anterior PSM. In this review, I further clarify the dynamic processes leading to segmental border formation in the developing mouse embryo.