Faculty Opinions recommendation of An Hh-dependent pathway in lateral plate mesoderm enables the generation of left/right asymmetry.

2009 ◽  
Author(s):  
Jonathan Eggenschwiler
Keyword(s):  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Left Right Asymmetry ◽  
Dependent Pathway

scholarly journals Antagonistic interactions in the zebrafish midline prior to the emergence of asymmetric gene expression are important for left–right patterning

2016 ◽  
Vol 371 (1710) ◽  
pp. 20150402 ◽  
Author(s):  
Rebecca D. Burdine ◽  
Daniel T. Grimes
Keyword(s):  
Gene Expression ◽  
Lateral Plate Mesoderm ◽  
Internal Organs ◽  
Lateral Plate ◽  
Left Right Asymmetry ◽  
Antagonistic Interactions

Left–right (L-R) asymmetry of the internal organs of vertebrates is presaged by domains of asymmetric gene expression in the lateral plate mesoderm (LPM) during somitogenesis. Ciliated L-R coordinators (LRCs) are critical for biasing the initiation of asymmetrically expressed genes, such as nodal and pitx2 , to the left LPM. Other midline structures, including the notochord and floorplate, are then required to maintain these asymmetries. Here we report an unexpected role for the zebrafish EGF-CFC gene one-eyed pinhead ( oep ) in the midline to promote pitx2 expression in the LPM. Late zygotic oep (LZ oep ) mutants have strongly reduced or absent pitx2 expression in the LPM, but this expression can be rescued to strong levels by restoring oep in midline structures only. Furthermore, removing midline structures from LZ oep embryos can rescue pitx2 expression in the LPM, suggesting the midline is a source of an LPM pitx2 repressor that is itself inhibited by oep . Reducing lefty1 activity in LZ oep embryos mimics removal of the midline, implicating lefty1 in the midline-derived repression. Together, this suggests a model where Oep in the midline functions to overcome a midline-derived repressor, involving lefty1 , to allow for the expression of left side-specific genes in the LPM. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’.

scholarly journals Gut endoderm is involved in the transfer of left-right asymmetry from the node to the lateral plate mesoderm in the mouse embryo

Development ◽  
2012 ◽  
Vol 139 (13) ◽  
pp. 2426-2435 ◽  
Author(s):  
R. S. Saund ◽  
M. Kanai-Azuma ◽  
Y. Kanai ◽  
I. Kim ◽  
M. T. Lucero ◽  
...  
Keyword(s):  
Mouse Embryo ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Left Right Asymmetry ◽  
Gut Endoderm

The homeobox gene Pitx2: mediator of asymmetric left-right signaling in vertebrate heart and gut looping

Development ◽  
1999 ◽  
Vol 126 (6) ◽  
pp. 1225-1234 ◽  
Author(s):  
M. Campione ◽  
H. Steinbeisser ◽  
A. Schweickert ◽  
K. Deissler ◽  
F. van Bebber ◽  
...  
Keyword(s):  
Ectopic Expression ◽  
Homeobox Gene ◽  
Zebrafish Embryos ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Left Right Asymmetry ◽  
The Right ◽  
Pitx2 Expression

Left-right asymmetry in vertebrates is controlled by activities emanating from the left lateral plate. How these signals get transmitted to the forming organs is not known. A candidate mediator in mouse, frog and zebrafish embryos is the homeobox gene Pitx2. It is asymmetrically expressed in the left lateral plate mesoderm, tubular heart and early gut tube. Localized Pitx2 expression continues when these organs undergo asymmetric looping morphogenesis. Ectopic expression of Xnr1 in the right lateral plate induces Pitx2 transcription in Xenopus. Misexpression of Pitx2 affects situs and morphology of organs. These experiments suggest a role for Pitx2 in promoting looping of the linear heart and gut.

scholarly journals Paraxial Nodal Expression Reveals a Novel Conserved Structure of the Left-Right Organizer in Four Mammalian Species

2016 ◽  
Vol 201 (2) ◽  
pp. 77-87 ◽  
Author(s):  
Silke S. Schröder ◽  
Nikoloz Tsikolia ◽  
Annette Weizbauer ◽  
Isabelle Hue ◽  
Christoph Viebahn
Keyword(s):  
Histological Analysis ◽  
Mammalian Species ◽  
Model Organism ◽  
Lateral Plate Mesoderm ◽  
Open Surface ◽  
Nodal Domain ◽  
Expression Domain ◽  
Lateral Plate ◽  
Vertebrate Embryo ◽  
Left Right Asymmetry

Nodal activity in the left lateral plate mesoderm is a conserved sign of irreversible left-right asymmetry at early somite stages of the vertebrate embryo. An earlier, paraxial nodal domain accompanies the emergence and initial extension of the notochord and is either left-sided, as in the chick and pig, or symmetrical, as in the mouse and rabbit; intriguingly, this interspecific dichotomy is mirrored by divergent morphological features of the posterior notochord (also known as the left-right organizer), which is ventrally exposed to the yolk sac cavity and carries motile cilia in the latter 2 species only. By introducing the cattle embryo as a new model organism for early left-right patterning, we present data to establish 2 groups of mammals characterized by both the morphology of the left-right organizer and the dynamics of paraxial nodal expression: presence and absence of a ventrally open surface of the early (plate-like) posterior notochord correlates with a symmetrical (in mice and rabbits) versus an asymmetrical (in pigs and cattle) paraxial nodal expression domain next to the notochordal plate. High-resolution histological analysis reveals that the latter domain defines in all 4 mammals a novel ‘parachordal' axial mesoderm compartment, the topography of which changes according to the specific regression of the similarly novel subchordal mesoderm during the initial phases of notochord development. In conclusion, the mammalian axial mesoderm compartment (1) shares critical conserved features despite the marked differences in early notochord morphology and early left-right patterning and (2) provides a dynamic topographical framework for nodal activity as part of the mammalian left-right organizer.

scholarly journals Presence of midline cilia supersedes the expression of Lefty1 in forming the midline barrier during the establishment of left-right asymmetry

2018 ◽  
Author(s):  
Natalia A Shylo ◽  
Dylan A Ramrattan ◽  
Scott D Weatherbee
Keyword(s):  
Transition Zone ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Left Isomerism ◽  
Left Right Asymmetry ◽  
Asymmetric Expression ◽  
R Symmetry

Cilia in the vertebrate left-right organizer are required for the original break in left-right (L-R) symmetry. Subsequently, proper L-R patterning relies on asymmetric expression of Nodal in the lateral plate mesoderm (LPM). Lefty1, expressed in the embryonic midline, has been defined as the midline barrier, restricting the expression of Nodal to the left LPM. Here we use the mouse ciliary transition zone mutant Mks1krc, that has left isomerism and bilateral expression of the NODAL target Pitx2, to reveal that the expression of Lefty1 in the midline is insufficient for the establishment of the midline barrier. We further show through a comparison of two Tmem107 mutants that cilia in the midline are required to supplement Lefty1 expression and establish the functional midline barrier. Tmem107null mutants have no cilia in the midline and display left isomerism due to the loss of the midline barrier, whereas Tmem107schlei hypomorphic mutants have numerous cilia in the node and the midline, leading to normal Lefty1 expression and L-R patterning. This study reveals a novel role for cilia in the maintenance of L-R asymmetry.

BMP signaling positively regulates Nodal expression during left right specification in the chick embryo

Development ◽  
2002 ◽  
Vol 129 (14) ◽  
pp. 3431-3440 ◽  
Author(s):  
M. Elisa Piedra ◽  
Mana A. Ros
Keyword(s):  
Bmp Signaling ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Positive Role ◽  
Molecular Control ◽  
Left And Right ◽  
Left Right Asymmetry ◽  
The Right ◽  
Rapid Activation ◽  
Positive Effect

Exogenous application of BMP to the lateral plate mesoderm (LPM) of chick embryos at the early somite stage had a positive effect on Nodal expression. BMP applications into the right LPM were followed by a rapid activation of Nodal, while applications into the left LPM resulted in expansion of the normal domain of Nodal expression. Conversely, blocking of BMP signaling by Noggin in the left LPM interfered with the activation of Nodal expression. These results support a positive role for endogenous BMP on Nodal expression in the LPM. We also report that BMP positively regulates the expression of Caronte, Snail and Cfc in both the left and right LPM. BMP-treated embryos had molecular impairment of the midline with downregulation of Lefty1, Brachyury and Shh but we also show that the midline defect was not sufficient to induce ectopic Nodal expression. We discuss our findings in the context of the known molecular control of the specification of left-right asymmetry.

scholarly journals A Xenopus nodal-related gene that acts in synergy with noggin to induce complete secondary axis and notochord formation

Development ◽  
1996 ◽  
Vol 122 (10) ◽  
pp. 3275-3282 ◽  
Author(s):  
K.D. Lustig ◽  
K. Kroll ◽  
E. Sun ◽  
R. Ramos ◽  
H. Elmendorf ◽  
...  
Keyword(s):  
Ectopic Expression ◽  
Signaling Proteins ◽  
Secreted Protein ◽  
Lateral Plate Mesoderm ◽  
Related Gene ◽  
Lateral Plate ◽  
Secondary Axis ◽  
Muscle Formation ◽  
Tailbud Stage ◽  
Left Right Asymmetry

Using a paracrine assay to screen for signaling proteins that could respecify ectodermal tissue, we isolated a Xenopus gene related to the mouse gene nodal, a member of the TGFbeta superfamily. The gene is expressed in three regions in the early Xenopus embryo: first in the gastrula organizer, then in two stripes of cells flanking the posterior notochord in late neurulae, and finally in lateral plate mesoderm restricted to the left side of tailbud-stage embryos. Ectopic expression of the gene induces muscle formation in ectodermal explants and partial secondary axes in whole embryos. Together with noggin, another secreted protein also present in the organizer, it induces notochord formation in ectodermal explants and complete secondary axes in whole embryos. These results suggest that the nodal-related gene may act together with noggin to induce axial pattern during gastrulation and also may play a role in left-right asymmetry generation in the post-gastrula embryo.

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