About this Research Topic
The formation of a complex organism from a single cell is one of the most amazing wonders of biology. Embryonic development is characterized by a careful regulation of cellular behaviors such that cells proliferate, migrate, differentiate and form tissues at the correct place and time. These processes are genetically controlled and depend both on the history of cells (lineage) and on the activities of signalling pathways, which coordinate the cell interactions leading to organogenesis.
A reduced number of master signalling pathways operate during development, acting repeatedly at different moments and regions in the embryo and eliciting diverse cellular responses. This raises the question of how cells integrate all the information they receive and respond in cell type-specific ways to the same signal. Classical embryology concepts such as organizers (groups of cells producing instructive signals) and competence (ability of cells to respond) are nowadays analyzed in molecular terms. With only a handful of pathways (Fgf, Hedgehog, Wnt, TGFß, Notch among the most important) and few intracellular effector cascades (for example MAPK) the embryos build all the complex organs. In recent years many advances have been obtained in identifying the signals acting during embryo development and understanding their properties and functions, which is relevant for human pathology and evolution. An important discovery made in this field is the conservation of signals and mechanisms, not only in evolutionary terms (similar genes and signals acting in distant organisms) but also in the reuse of the same signalling pathways at different times and places in the embryos. Moreover, many of those are involved in adult tissue homeostasis.
This research topic aims to provide a forum for experts in cell and developmental biology to share recent advances in the field of signalling during embryonic development. Topics to be discussed include the basics of the “communication” system such as regulation of synthesis, modification and secretion of the signal by producing cells; control of diffusion of the signal; interaction with the extracellular matrix; receptor specificity in the receiving cells and intracellular signal transduction cascades. Signalling cross talk in cell differentiation and how particular signals control the development of specific organs are major lines of research. Emerging themes are the control of tissue morphogenesis by physical forces (mechanotransduction); how signalling may modulate biological noise; mathematical modelling of morphogen gradients and signals controlling biological clocks. A final aspect not to be overlooked is the control of duration of signalling at the cellular and embryonic levels.
Understanding developmental signalling pathways is important for several reasons. It gives us information about basic mechanisms of cell function and interactions needed for morphogenesis and organogenesis. It uncovers the basis of congenital malformations, since errors at any step of cell signalling during development are a major cause of defects. It gives us clues to understand the mechanisms operating in evolution to attain diversity in form and function. Finally, it allows the identification of possible causes of disease in the adult (such as cancer or degenerative diseases) pinpointing possible targets for therapeutic approaches.
Keywords: Signaling pathways, Embryo, Organogenesis, Pattern Formation, Differentiation
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