Coelom formation: binary decision of the lateral plate mesoderm is controlled by the ectoderm

Development ◽  
1999 ◽  
Vol 126 (18) ◽  
pp. 4129-4138 ◽  
Author(s):  
N. Funayama ◽  
Y. Sato ◽  
K. Matsumoto ◽  
T. Ogura ◽  
Y. Takahashi
Keyword(s):  
Molecular Mechanisms ◽  
The Body ◽  
Lateral Plate Mesoderm ◽  
Coelomic Cavity ◽  
Cell Sheets ◽  
Lateral Plate ◽  
Binary Decision ◽  
Evolutionary Aspects ◽  
Coelom Formation

Most triploblastic animals including vertebrates have a coelomic cavity that separates the outer and inner components of the body. The coelom is lined by two different tissue components, somatopleure and splanchnopleure, which are derived from the lateral plate region. Thus, the coelom is constructed as a result of a binary decision during early specification of the lateral plate. In this report we studied the molecular mechanisms of this binary decision. We first demonstrate that the splitting of the lateral plate into the two cell sheets progresses in an anteroposterior order and this progression is not coordinated with that of the somitic segmentation. By a series of embryological manipulations we found that young splanchnic mesoderm is still competent to be respecified as somatic mesoderm, and the ectoderm overlying the lateral plate is sufficient for this redirection. The lateral ectoderm is also required for maintenance of the somatic character of the mesoderm. Thus, the ectoderm plays at least two roles in the early subdivision of the lateral plate: specification and maintenance of the somatic mesoderm. We also show that the latter interactions are mediated by BMP molecules that are localized in the lateral ectoderm. Evolutionary aspects of the coelom formation are also considered.

scholarly journals Analyses of Avascular Mutants Reveal Unique Transcriptomic Signature of Non-conventional Endothelial Cells

2020 ◽  
Vol 8 ◽  
Author(s):  
Boryeong Pak ◽  
Christopher E. Schmitt ◽  
Woosoung Choi ◽  
Jun-Dae Kim ◽  
Orjin Han ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Molecular Mechanisms ◽  
Lineage Tracing ◽  
Molecular Characteristics ◽  
Lateral Plate Mesoderm ◽  
Rna Seq ◽  
Developmental History ◽  
Lateral Plate ◽  
Developmental Origin ◽  
Transcriptomic Signature

Endothelial cells appear to emerge from diverse progenitors. However, to which extent their developmental origin contributes to define their cellular and molecular characteristics remains largely unknown. Here, we report that a subset of endothelial cells that emerge from the tailbud possess unique molecular characteristics that set them apart from stereotypical lateral plate mesoderm (LPM)-derived endothelial cells. Lineage tracing shows that these tailbud-derived endothelial cells arise at mid-somitogenesis stages, and surprisingly do not require Npas4l or Etsrp function, indicating that they have distinct spatiotemporal origins and are regulated by distinct molecular mechanisms. Microarray and single cell RNA-seq analyses reveal that somitogenesis- and neurogenesis-associated transcripts are over-represented in these tailbud-derived endothelial cells, suggesting that they possess a unique transcriptomic signature. Taken together, our results further reveal the diversity of endothelial cells with respect to their developmental origin and molecular properties, and provide compelling evidence that the molecular characteristics of endothelial cells may reflect their distinct developmental history.

Two distinct endothelial lineages in ontogeny, one of them related to hemopoiesis

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1363-1371 ◽  
Author(s):  
L. Pardanaud ◽  
D. Luton ◽  
M. Prigent ◽  
L.M. Bourcheix ◽  
M. Catala ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Body Wall ◽  
The Body ◽  
Paraxial Mesoderm ◽  
Lateral Plate Mesoderm ◽  
Hemopoietic Precursors ◽  
Lateral Plate ◽  
Visceral Organs ◽  
Endothelial Precursors

We have shown previously by means of quail/chick transplantations that external and visceral organs, i.e., somatopleural and splanchnopleural derivatives, acquire their endothelial network through different mechanisms, namely immigration (termed angiogenesis) versus in situ emergence of precursors (or vasculogenesis). We have traced the distribution of QH1-positive cells in chick hosts after replacement of the last somites by quail somites (orthotopic grafts) or lateral plate mesoderm (heterotopic grafts). The results lead to the conclusion that the embryo becomes vascularized by endothelial precursors from two distinct regions, splanchnopleural mesoderm and paraxial mesoderm. The territories respectively vascularized are complementary, precursors from the paraxial mesoderm occupy the body wall and kidney, i.e., they settle along with the other paraxial mesoderm derivatives and colonize the somatopleure. The precursors from the two origins have distinct recognition and potentialities properties: endothelial precursors of paraxial origin are barred from vascularizing visceral organs and from integrating into the floor of the aorta, and are never associated with hemopoiesis; splanchnopleural mesoderm grafted in the place of somites, gives off endothelial cells to body wall and kidney but also visceral organs. It gives rise to hemopoietic precursors in addition to endothelial cells.

scholarly journals Expression of (beta)-catenin in the developing chick myotome is regulated by myogenic signals

Development ◽  
2000 ◽  
Vol 127 (19) ◽  
pp. 4105-4113
Author(s):  
M. Schmidt ◽  
M. Tanaka ◽  
A. Munsterberg
Keyword(s):  
Gene Expression ◽  
Wnt Pathway ◽  
Molecular Mechanisms ◽  
Signalling Pathways ◽  
Specific Gene ◽  
Beta Catenin ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Cell Specification ◽  
Myogenic Precursor

The developmental signals that govern cell specification and differentiation in vertebrate somites are well understood. However, little is known about the downstream signalling pathways involved. We have shown previously that a combination of Shh protein and Wnt1 or Wnt3a-expressing fibroblasts is sufficient to activate skeletal muscle-specific gene expression in somite explants. Here, we have examined the molecular mechanisms by which the Wnt-mediated signal acts on myogenic precursor cells. We show that chick frizzled 1 (Fz1), beta-catenin and Lef1 are expressed during somitogenesis. Lef1 and beta-catenin transcripts become restricted to the developing myotome. Furthermore, beta-catenin is expressed prior to the time at which MyoD transcripts can be detected. Expression of beta-catenin mRNA is regulated by positive and negative signals derived from neural tube, notochord and lateral plate mesoderm. These signals include Bmp4, Shh and Wnt1/Wnt3a itself. In somite explants, Fz1, beta-catenin and Lef1 are expressed prior to activation of myogenesis in response to Shh and Wnt signals. Thus, our data show that a combination of Shh and Wnt1 upregulates expression of Wnt pathway components in developing somites prior to myogenesis. Thus, Wnt1 could act through beta-catenin on cells in the myotome.

Persistent myogenic capacity of the dermomyotome dorsomedial lip and restriction of myogenic competence

Development ◽  
2002 ◽  
Vol 129 (16) ◽  
pp. 3873-3885 ◽  
Author(s):  
Sara J. Venters ◽  
Charles P. Ordahl
Keyword(s):  
Primary Source ◽  
The Body ◽  
Paraxial Mesoderm ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Myogenic Potential ◽  
Epithelial Sheet ◽  
Mechanistic Basis ◽  
Somitic Mesoderm ◽  
Serial Transplantation

The dorsomedial lip (DML) of the somite dermomyotome is the source of cells for the early growth and morphogenesis of the epaxial primary myotome and the overlying dermomyotome epithelium. We have used quail-chick transplantation to investigate the mechanistic basis for DML activity. The ablated DML of chick wing-level somites was replaced with tissue fragments from various mesoderm regions of quail embryos and their capacity to form myotomal tissue assessed by confocal microscopy. Transplanted fragments from the epithelial sheet region of the dermomyotome exhibited full DML growth and morphogenetic capacity. Ventral somite fragments (sclerotome), head paraxial mesoderm or non-paraxial (lateral plate) mesoderm tested in this assay were each able to expand mitotically in concert with the surrounding paraxial mesoderm, although no myogenic potential was evident. When ablated DMLs were replaced with fragments of the dermomyotome ventrolateral lip of wing-level somites or pre-somitic mesoderm (segmental plate), myotome development was evident but was delayed or otherwise limited in some cases. Timed DML ablation-replacement experiments demonstrate that DML activity is progressive throughout the embryonic period (to at least E7) and its continued presence is necessary for the complete patterning of each myotome segment. The results of serial transplantation and BrdU pulse-chase experiments are most consistent with the conclusion that the DML consists of a self-renewing population of progenitor cells that are the primary source of cells driving the growth and morphogenesis of the myotome and dermomyotome in the epaxial domain of the body.

scholarly journals Homeobox genes and connective tissue patterning

Development ◽  
1995 ◽  
Vol 121 (3) ◽  
pp. 693-705 ◽  
Author(s):  
G. Oliver ◽  
R. Wehr ◽  
N.A. Jenkins ◽  
N.G. Copeland ◽  
B.N. Cheyette ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Connective Tissue ◽  
Early Development ◽  
Molecular Mechanisms ◽  
Homeobox Genes ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Tissue Patterning

In vertebrates, limb tendons are derived from cells that migrate from the lateral plate mesoderm during early development. While some of the developmental steps leading to the formation of these tissues are known, little is known about the molecular mechanisms controlling them. We have identified two murine homeobox-containing genes, Six 1 and Six 2, which are expressed in a complementary fashion during the development of limb tendons. Transcripts for both genes are found in different sets of phalangeal tendons. Six 1 and Six 2 also are expressed in skeletal and smooth muscle, respectively. These genes may participate in the patterning of the distal tendons of the limb phalanges by setting positional values along the limb axes.

Mesodermal subdivision along the mediolateral axis in chicken controlled by different concentrations of BMP-4

Development ◽  
1997 ◽  
Vol 124 (10) ◽  
pp. 1975-1984 ◽  
Author(s):  
A. Tonegawa ◽  
N. Funayama ◽  
N. Ueno ◽  
Y. Takahashi
Keyword(s):  
Early Development ◽  
Molecular Mechanisms ◽  
Lateral Plate Mesoderm ◽  
Tgf Beta ◽  
Presomitic Mesoderm ◽  
Lateral Plate ◽  
Chicken Embryos ◽  
Cos Cells ◽  
Low Level ◽  
High Level

Molecular mechanisms by which the mesoderm is subdivided along the mediolateral axis in early chicken embryos have been studied. When the presomitic mesoderm (medial mesoderm) was transplanted into the lateral plate, the graft was transformed into lateral plate tissue, indicating that the primitive somite was not fully committed and that the lateral plate has a cue for mesodermal lateralization. Since the lateral plate expresses a high level of BMP-4 mRNA, a member of the TGF-beta family, we hypothesized that it is the molecule responsible for the lateralization of the somite. To test this, we transplanted COS cells producing BMP-4 into the presomitic region. Those cells locally prevented the presomitic cells from differentiating into somites, converting them instead into lateral plate mesoderm, which was revealed by expression of cytokeratin mRNA, a marker for the lateral plate. The effect was dependent on the level of effective BMP-4: with a high level of BMP-4, the somite was transformed completely to lateral plate; with a low level, the somite formed but was occupied by the lateral somitic component expressing cSim 1, a marker for the lateral somite. These results suggest that different thresholds of effective BMP-4 determine distinct subtypes of the mesoderm as a lateralizer during early development.

Toxicology

2017 ◽  
Author(s):  
Robert Laumbach ◽  
Michael Gochfeld
Keyword(s):  
Molecular Mechanisms ◽  
Molecular Targets ◽  
Toxicity Testing ◽  
The Body ◽  
Toxic Substances ◽  
Basic Principles ◽  
Practical Applications ◽  
Mechanisms Of Toxicity ◽  
Body Distribution ◽  
Threshold Doses

This chapter describes the basic principles of toxicology and their application to occupational and environmental health. Topics covered include pathways that toxic substances may take from sources in the environment to molecular targets in the cells of the body where toxic effects occur. These pathways include routes of exposure, absorption into the body, distribution to organs and tissues, metabolism, storage, and excretion. The various types of toxicological endpoints are discussed, along with the concepts of dose-response relationships, threshold doses, and the basis of interindividual differences and interspecies differences in response to exposure to toxic substances. The diversity of cellular and molecular mechanisms of toxicity, including enzyme induction and inhibition, oxidative stress, mutagenesis, carcinogenesis, and teratogenesis, are discussed and the chapter concludes with examples of practical applications in clinical evaluation and in toxicity testing.

scholarly journals The AF-6 Homolog Canoe Acts as a Rap1 Effector During Dorsal Closure of the Drosophila Embryo

Genetics ◽  
2003 ◽  
Vol 165 (1) ◽  
pp. 159-169
Author(s):  
Benjamin Boettner ◽  
Phoebe Harjes ◽  
Satoshi Ishimaru ◽  
Michael Heke ◽  
Hong Qing Fan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Genetic Interaction ◽  
Critical Role ◽  
Adherens Junction ◽  
Small Gtpases ◽  
Drosophila Embryo ◽  
Dorsal Closure ◽  
Cell Sheets ◽  
Jnk Pathway

Abstract Rap1 belongs to the highly conserved Ras subfamily of small GTPases. In Drosophila, Rap1 plays a critical role in many different morphogenetic processes, but the molecular mechanisms executing its function are unknown. Here, we demonstrate that Canoe (Cno), the Drosophila homolog of mammalian junctional protein AF-6, acts as an effector of Rap1 in vivo. Cno binds to the activated form of Rap1 in a yeast two-hybrid assay, the two molecules colocalize to the adherens junction, and they display very similar phenotypes in embryonic dorsal closure (DC), a process that relies on the elongation and migration of epithelial cell sheets. Genetic interaction experiments show that Rap1 and Cno act in the same molecular pathway during DC and that the function of both molecules in DC depends on their ability to interact. We further show that Rap1 acts upstream of Cno, but that Rap1, unlike Cno, is not involved in the stimulation of JNK pathway activity, indicating that Cno has both a Rap1-dependent and a Rap1-independent function in the DC process.

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