Uncoupling segmentation and somitogenesis in the chick presomitic mesoderm

Palmeirim, Isabel; Dubrulle, Julien; Henrique, Domingos; Ish‐Horowicz, David; Pourquié, Olivier

doi:10.1002/(sici)1520-6408(1998)23:1<77::aid-dvg8>3.0.co;2-3

Cited by 90 publications

(53 citation statements)

References 35 publications

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“…The data are consistent with previous findings, which demonstrated that cells of the PSM are not a homogeneous population in terms of their maturation status, but that they are intrinsically endowed with some degree of positional identity with respect to their anteroposterior location along the PSM (Dubrulle et al, 2001, Palmeirim et al, 1998. One factor that plays a key role in this process of maturation specification is FGF8, which has been shown to be instrumental in maintaining a caudal identity in PSM cells (Dubrulle et al, 2001, Sawada et al, 2001.…”

Section: Discussionsupporting

confidence: 92%

Synchronised cycling gene oscillations in presomitic mesoderm cells require cell-cell contact

Maroto¹,

Dale²,

Dequéant³

et al. 2005

Int. J. Dev. Biol.

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Segmentation of the vertebrate body axis is initiated early in development with the sequential formation of somites. Somitogenesis is temporally regulated by a molecular oscillator, the segmentation clock, which acts within presomitic mesoderm (PSM) cells to drive periodic expression of the cyclic genes. We have investigated the kinetics of the progression of cycling gene expression along the PSM. Here we show that c-hairy1 and c-hairy2 mRNA expression traverses the PSM in an entirely progressive manner and that both these genes and c-Lfng maintain a similar anterior limit of expression during each cycle. However, some differences are seen regarding both the onset of a new oscillation of these genes and the duration of their expression in the caudal PSM. We also investigated whether oscillating cyclic gene expression in the PSM is entirely cell autonomous. We find that while small PSM explants are still able to maintain their oscillation schedule, once they are dissociated, PSM cells are no longer able to maintain synchronous oscillations. The results imply that cell communication or a community effect is essential for the normal pattern of cyclic gene expression in these cells.

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Section: Discussionsupporting

confidence: 92%

Synchronised cycling gene oscillations in presomitic mesoderm cells require cell-cell contact

Maroto¹,

Dale²,

Dequéant³

et al. 2005

Int. J. Dev. Biol.

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“…In amniotes, this process is controlled by the surface ectoderm, as ectoderm ablation prevents somitogenesis but not segmentation (Š ošić et al, 1997;Palmeirim et al, 1998). In addition, the transcription factor Paraxis, which is crucial for epithelial somite but not segment formation, is induced by ectodermal signals and acts independent from Notch-Delta/Serrate signalling (Burgess et al, 1996;Barnes et al, 1997;Š ošić et al, 1997;Johnson et al, 2001).…”

Section: Introductionsupporting

confidence: 92%

Early mesodermal phenotypes in splotch suggest a role for Pax3 in the formation of epithelial somites

Schubert

Tremblay²,

Mansouri

et al. 2001

Developmental Dynamics

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The paired box containing transcription factor Pax3 is a crucial regulator of dermomyotome and muscle development. However, the allelic series of Pax3/Splotch mutants also displays characteristic vertebral column malformations, which do not result from defective dorsoventral somite pattern. Rather, vertebral column and sclerotomal phenotypes are reminiscent of the phenotypes observed in the segmentation/somitogenesis mutants rachiterata and pudgy. Moreover, rostrocaudal somite pattern and somitic boundaries are disturbed in Splotch as monitored by the expression of Uncx4.1 and Lunatic fringe. Alterations in EphA4, Dll1, and Uncx4.1 expression are evident already in the condensing paraxial mesoderm, correlating with the first phase of Pax3 expression before and during somite formation. This finding suggests an early function of Pax3 during the formation of epithelial somites.

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“…However, morphological somite formation does not occur in isolated cultured PSMs. For somites to form, ectoderm must be in contact with the PSM (Borycki et al, 2000;Borycki et al, 1998;Correia and Conlon, 2000;Palmeirim et al, 1998), suggesting that ectodermal signals, most likely Wnts (Borycki et al, 2000;Schmidt et al, 2004), are essential for morphological somite formation.…”

Section: Introductionmentioning

confidence: 55%

Redefining the role of ectoderm in somitogenesis: a player in the formation of the fibronectin matrix of presomitic mesoderm

et al. 2007

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The absence of ectoderm impairs somite formation in cultured presomitic mesoderm (PSM) explants, suggesting that an ectodermderived signal is essential for somitogenesis. Here we show in chick that the standard enzymatic treatments used for explant isolation destroy the fibronectin matrix surrounding the anterior PSM, which fails to form somites when cultured for 6 hours. By contrast, explants isolated with collagenase retain their fibronectin matrix and form somites under identical culture conditions. The additional presence of ectoderm enhances somite formation, whereas endoderm has no effect. Furthermore, we show that pancreatin-isolated PSM explants cultured in fibronectin-supplemented medium, form significantly more somites than control explants. Interestingly, ectoderm is the major producer of fibronectin (Fn1) transcripts, whereas all but the anterior-most region of the PSM expresses the fibronectin assembly receptor, integrin ␣5 (Itga5). We thus propose that the ectoderm-derived fibronectin is assembled by mesodermal ␣5␤1 integrin on the surface of the PSM. Finally, we demonstrate that inhibition of fibronectin fibrillogenesis in explants with ectoderm abrogates somitogenesis. We conclude that a fibronectin matrix is essential for morphological somite formation and that a major, previously unrecognised role of ectoderm in somitogenesis is the synthesis of fibronectin.

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Uncoupling segmentation and somitogenesis in the chick presomitic mesoderm

Cited by 90 publications

References 35 publications

Synchronised cycling gene oscillations in presomitic mesoderm cells require cell-cell contact

Synchronised cycling gene oscillations in presomitic mesoderm cells require cell-cell contact

Early mesodermal phenotypes in splotch suggest a role for Pax3 in the formation of epithelial somites

Redefining the role of ectoderm in somitogenesis: a player in the formation of the fibronectin matrix of presomitic mesoderm

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