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Seminars in Cell & Developmental Biology Apr 2020Convergent extension is a fundamental morphogenetic process that underlies not only the generation of the elongated vertebrate body plan from the initially radially... (Review)
Review
Convergent extension is a fundamental morphogenetic process that underlies not only the generation of the elongated vertebrate body plan from the initially radially symmetrical embryo, but also the specific shape changes characteristic of many individual tissues. These tissue shape changes are the result of specific cell behaviors, coordinated in time and space, and affected by the physical properties of the tissue. While mediolateral cell intercalation is the classic cellular mechanism for producing tissue convergence and extension, other cell behaviors can also provide similar tissue-scale distortions or can modulate the effects of mediolateral cell intercalation to sculpt a specific shape. Regulation of regional tissue morphogenesis through planar polarization of the variety of underlying cell behaviors is well-recognized, but as yet is not well understood at the molecular level. Here, we review recent advances in understanding the cellular basis for convergence and extension and its regulation.
Topics: Animals; Embryo, Mammalian; Mesoderm; Morphogenesis
PubMed: 31734039
DOI: 10.1016/j.semcdb.2019.11.002 -
Current Topics in Developmental Biology 2024The Segmentation Clock is a tissue-level patterning system that enables the segmentation of the vertebral column precursors into transient multicellular blocks called... (Review)
Review
The Segmentation Clock is a tissue-level patterning system that enables the segmentation of the vertebral column precursors into transient multicellular blocks called somites. This patterning system comprises a set of elements that are essential for correct segmentation. Under the so-called "Clock and Wavefront" model, the system consists of two elements, a genetic oscillator that manifests itself as traveling waves of gene expression, and a regressing wavefront that transforms the temporally periodic signal encoded in the oscillations into a permanent spatially periodic pattern of somite boundaries. Over the last twenty years, every new discovery about the Segmentation Clock has been tightly linked to the nomenclature of the "Clock and Wavefront" model. This constrained allocation of discoveries into these two elements has generated long-standing debates in the field as what defines molecularly the wavefront and how and where the interaction between the two elements establishes the future somite boundaries. In this review, we propose an expansion of the "Clock and Wavefront" model into three elements, "Clock", "Wavefront" and signaling gradients. We first provide a detailed description of the components and regulatory mechanisms of each element, and we then examine how the spatiotemporal integration of the three elements leads to the establishment of the presumptive somite boundaries. To be as exhaustive as possible, we focus on the Segmentation Clock in zebrafish. Furthermore, we show how this three-element expansion of the model provides a better understanding of the somite formation process and we emphasize where our current understanding of this patterning system remains obscure.
Topics: Animals; Body Patterning; Gene Expression Regulation, Developmental; Somites; Mesoderm; Zebrafish; Signal Transduction; Biological Clocks
PubMed: 38729682
DOI: 10.1016/bs.ctdb.2023.11.001 -
Nature Reviews. Molecular Cell Biology Nov 2014Segmentation of the paraxial mesoderm is a major event of vertebrate development that establishes the metameric patterning of the body axis. This process involves the... (Review)
Review
Segmentation of the paraxial mesoderm is a major event of vertebrate development that establishes the metameric patterning of the body axis. This process involves the periodic formation of sequential units, termed somites, from the presomitic mesoderm. Somite formation relies on a molecular oscillator, the segmentation clock, which controls the rhythmic activation of several signalling pathways and leads to the oscillatory expression of a subset of genes in the presomitic mesoderm. The response to the periodic signal of the clock, leading to the establishment of the segmental pre-pattern, is gated by a system of travelling signalling gradients, often referred to as the wavefront. Recent studies have advanced our understanding of the molecular mechanisms involved in the generation of oscillations and how they interact and are coordinated to activate the segmental gene expression programme.
Topics: Animals; Biological Clocks; Body Patterning; CLOCK Proteins; Embryonic Development; Gene Expression Regulation, Developmental; Humans; Mesoderm; Models, Biological; Receptors, Notch; Signal Transduction; Vertebrates; Wnt Proteins
PubMed: 25335437
DOI: 10.1038/nrm3891 -
The Journal of Biological Chemistry Jun 2017Critical steps in the specification of embryonic cell lineages occur after implantation, but gaining insight into the molecular details of these cellular processes has... (Review)
Review
Critical steps in the specification of embryonic cell lineages occur after implantation, but gaining insight into the molecular details of these cellular processes has been challenging. Jin and co-workers now report the transcriptomic signatures and molecular heterogeneity of more than 600 single cells from mouse embryos at days 5.5 and 6.5, advancing our understanding of how early embryonic cells make cell-fate decisions into mesoderm and endoderm lineages.
Topics: Animals; Cell Lineage; Embryo, Mammalian; Endoderm; Mesoderm; Mice
PubMed: 28600307
DOI: 10.1074/jbc.H117.780585 -
Seminars in Cell & Developmental Biology Dec 2017Pluripotent stem cells represent important tools for both basic and translational science as they enable to study mechanisms of development, model diseases in vitro and... (Review)
Review
Pluripotent stem cells represent important tools for both basic and translational science as they enable to study mechanisms of development, model diseases in vitro and provide a potential source of tissue-specific progenitors for cell therapy. Concomitantly with the increasing knowledge of the molecular mechanisms behind activation of the skeletal myogenic program during embryonic development, novel findings in the stem cell field provided the opportunity to begin recapitulating in vitro the events occurring during specification of the myogenic lineage. In this review, we will provide a perspective of the molecular mechanisms responsible for skeletal myogenic commitment in the embryo and how this knowledge was instrumental for specifying this lineage from pluripotent stem cells. In addition, we will discuss the current limitations for properly recapitulating skeletal myogenesis in the petri dish, and we will provide insights about future applications of pluripotent stem cell-derived myogenic cells.
Topics: Animals; Cell Differentiation; Cell Lineage; Gene Expression Regulation, Developmental; Humans; Mesoderm; Muscle Development; Muscle Proteins; Muscle, Skeletal; Pluripotent Stem Cells
PubMed: 29107681
DOI: 10.1016/j.semcdb.2017.10.031 -
Cellular and Molecular Life Sciences :... May 2020Vertebrate cranial mesoderm is a discrete developmental unit compared to the mesoderm below the developing neck. An extraordinary feature of the cranial mesoderm is that... (Review)
Review
Vertebrate cranial mesoderm is a discrete developmental unit compared to the mesoderm below the developing neck. An extraordinary feature of the cranial mesoderm is that it includes a common progenitor pool contributing to the chambered heart and the craniofacial skeletal muscles. This striking developmental potential and the excitement it generated led to advances in our understanding of cranial mesoderm developmental mechanism. Remarkably, recent findings have begun to unravel the origin of its distinct developmental characteristics. Here, we take a detailed view of the ontogenetic trajectory of cranial mesoderm and its regulatory network. Based on the emerging evidence, we propose that cranial and posterior mesoderm diverge at the earliest step of the process that patterns the mesoderm germ layer along the anterior-posterior body axis. Further, we discuss the latest evidence and their impact on our current understanding of the evolutionary origin of cranial mesoderm. Overall, the review highlights the findings from contemporary research, which lays the foundation to probe the molecular basis of unique developmental potential and evolutionary origin of cranial mesoderm.
Topics: Animals; Biological Evolution; Gene Expression Regulation, Developmental; Humans; Mesoderm; Muscle Development; Muscle, Skeletal; Neural Crest; Skull; Vertebrates
PubMed: 31722070
DOI: 10.1007/s00018-019-03373-1 -
The International Journal of... 2017The vertebrate head characteristically exhibits a complex pattern with sense organs, brain, paired eyes and jaw muscles, and the brain case is not found in other... (Review)
Review
The vertebrate head characteristically exhibits a complex pattern with sense organs, brain, paired eyes and jaw muscles, and the brain case is not found in other chordates. How the extant vertebrate head has evolved remains enigmatic. Historically, there have been two conflicting views on the origin of the vertebrate head, segmental and non-segmental views. According to the segmentalists, the vertebrate head is organized as a metameric structure composed of segments equivalent to those in the trunk; a metamere in the vertebrate head was assumed to consist of a somite, a branchial arch and a set of cranial nerves, considering that the head evolved from rostral segments of amphioxus-like ancestral vertebrates. Non-segmentalists, however, considered that the vertebrate head was not segmental. In that case, the ancestral state of the vertebrate head may be non-segmented, and rostral segments in amphioxus might have been secondarily gained, or extant vertebrates might have evolved through radical modifications of amphioxus-like ancestral vertebrate head. Comparative studies of mesodermal development in amphioxus and vertebrate gastrula embryos have revealed that mesodermal gene expressions become segregated into two domains anteroposteriorly to specify the head mesoderm and trunk mesoderm only in vertebrates; in this segregation, key genes such as delta and hairy, involved in segment formation, are expressed in the trunk mesoderm, but not in the head mesoderm, strongly suggesting that the head mesoderm of extant vertebrates is not segmented. Taken together, the above finding possibly adds a new insight into the origin of the vertebrate head; the vertebrate head mesoderm would have evolved through an anteroposterior polarization of the paraxial mesoderm if the ancestral vertebrate had been amphioxus-like.
Topics: Animals; Body Patterning; Cephalochordata; Gene Expression Regulation, Developmental; Head; Lancelets; Models, Biological; Somites; Vertebrates
PubMed: 29319111
DOI: 10.1387/ijdb.170121to -
Circulation Research Jan 2015The heart is the first organ to form during embryonic development. Given the complex nature of cardiac differentiation and morphogenesis, it is not surprising that some... (Review)
Review
The heart is the first organ to form during embryonic development. Given the complex nature of cardiac differentiation and morphogenesis, it is not surprising that some form of congenital heart disease is present in ≈1 percent of newborns. The molecular determinants of heart development have received much attention over the past several decades. This has been driven in large part by an interest in understanding the causes of congenital heart disease coupled with the potential of using knowledge from developmental biology to generate functional cells and tissues that could be used for regenerative medicine purposes. In this review, we highlight the critical signaling pathways and transcription factor networks that regulate cardiomyocyte lineage specification in both in vivo and in vitro models. Special focus will be given to epigenetic regulators that drive the commitment of cardiomyogenic cells from nascent mesoderm and their differentiation into chamber-specific myocytes, as well as regulation of myocardial trabeculation.
Topics: Animals; Cell Differentiation; Cell Lineage; Gene Expression Regulation, Developmental; Gene Regulatory Networks; Humans; Mesoderm; Myocardium; Myocytes, Cardiac; Signal Transduction
PubMed: 25593278
DOI: 10.1161/CIRCRESAHA.116.302752 -
Current Topics in Developmental Biology 2020Mesoderm and endoderm internalization in the Xenopus embryo are based on a number of region-specific morphogenetic processes that co-act in the vegetal half of the... (Review)
Review
Mesoderm and endoderm internalization in the Xenopus embryo are based on a number of region-specific morphogenetic processes that co-act in the vegetal half of the gastrula. In the multilayered wall surrounding the blastocoel, the apical layer engages in bottle cell formation and associated invagination and involution movements, and in cell intercalation in the plane of the layer. Of these epithelial-type processes, only bottle cell formation has been analyzed mechanistically. In the deep layers of the blastocoel wall, cell-on-cell migration drives the internalization of mesoderm by various forms of involution and of the endodermal cell mass by vegetal rotation. In the mesoderm, cells migrate in a mesenchymal mode with the aid of locomotory protrusions, whereas cells of the vegetal cell mass resemble free bottle cells that engage in ingression-type amoeboid migration. Cells rearrange by differential migration leading to parallel or orthogonal forms of intercalation and respective types of convergent extension. The interaction of the various apical and deep layer processes gives rise to dorsal multilayer invagination, ventrolateral internal involution, peak involution and orthogonal convergent extension of the dorsal posterior mesoderm, vegetal rotation, and blastopore constriction. It is speculated how these multilayer gastrulation movements could be derived from mechanisms in invertebrate single-epithelium gastrulae.
Topics: Animals; Cell Movement; Embryo, Nonmammalian; Endoderm; Gene Expression Regulation, Developmental; Mesoderm; Morphogenesis; Signal Transduction; Xenopus Proteins; Xenopus laevis
PubMed: 31959290
DOI: 10.1016/bs.ctdb.2019.09.002 -
European Journal of Cell Biology Sep 2018The endothelial to mesenchymal transition (EndMT) is the process by which endothelial cells lose a portion of their cellular features and obtain certain characteristics... (Review)
Review
The endothelial to mesenchymal transition (EndMT) is the process by which endothelial cells lose a portion of their cellular features and obtain certain characteristics of mesenchymal cells, including loss of tight junctions, increased motility, and increased secretion of extracellular matrix proteins. EndMT is involved in cardiac development and a variety of diseases processes, such as vascular or tissue fibrosis and tumor. However, its role in specific diseases remains under debate. This review summarizes EndMT-related diseases, existing controversies, different types of EndMT, and molecules and signaling pathways associated with the process.
Topics: Animals; Disease; Endothelial Cells; Humans; Mesoderm; Models, Biological; Organogenesis; Signal Transduction
PubMed: 30082099
DOI: 10.1016/j.ejcb.2018.07.005