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Wolfgang Wurst - One of the best experts on this subject based on the ideXlab platform.
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Sharpening of expression domains induced by transcription and microRNA regulationwithin a spatio-temporal model of mid-hindbrain boundary formation
BMC Systems Biology, 2013Co-Authors: Sabrina Hock, Wolfgang Wurst, Nilima Prakash, Jan Hasenauer, Dominik Wittmann, Dominik Lutter, Dietrich Trümbach, Fabian J TheisAbstract:Background The establishment of the mid-hindbrain region in vertebrates is mediated by theIsthmic Organizer, an embryonic secondary Organizer characterized by awell-defined pattern of locally restricted gene expression domains with sharplydelimited boundaries. While the function of the Isthmic Organizer at themid-hindbrain boundary has been subject to extensive experimental studies, itremains unclear how this well-defined spatial gene expression pattern, which isessential for proper Isthmic Organizer function, is established during vertebratedevelopment. Because the secreted Wnt1 protein plays a prominent role in IsthmicOrganizer function, we focused in particular on the refinement of Wnt1 gene expression in this context. Results We analyzed the dynamics of the corresponding murine gene regulatory network andthe related, diffusive signaling proteins using a macroscopic model for thebiological two-scale signaling process . Despite the discontinuity arisingfrom the sharp gene expression domain boundaries, we proved the existence ofunique, positive solutions for the partial differential equation system. Thisenabled the numerically and analytically analysis of the formation and stabilityof the expression pattern. Notably, the calculated expression domain of Wnt1 has no sharp boundary in contrast to experimental evidence. Wesubsequently propose a post-transcriptional regulatory mechanism for Wnt1 miRNAs which yields the observed sharp expression domain boundaries. Weestablished a list of candidate miRNAs and confirmed their expression pattern byradioactive in situ hybridization. The miRNA miR-709 was identified as apotential regulator of Wnt1 mRNA, which was validated by luciferasesensor assays. Conclusion In summary, our theoretical analysis of the gene expression pattern induction atthe mid-hindbrain boundary revealed the need to extend the model by an additional Wnt1 regulation. The developed macroscopic model of a two-scaleprocess facilitate the stringent analysis of other morphogen-based patterningprocesses.
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Sharpening of expression domains induced by transcription and microRNA regulation within a spatio-temporal model of mid-hindbrain boundary formation.
BMC systems biology, 2013Co-Authors: Sabrina Hock, Wolfgang Wurst, Nilima Prakash, Jan Hasenauer, Dominik Lutter, Dietrich Trümbach, Dominik M. Wittmann, Fabian J TheisAbstract:The establishment of the mid-hindbrain region in vertebrates is mediated by theIsthmic Organizer, an embryonic secondary Organizer characterized by awell-defined pattern of locally restricted gene expression domains with sharplydelimited boundaries. While the function of the Isthmic Organizer at themid-hindbrain boundary has been subject to extensive experimental studies, itremains unclear how this well-defined spatial gene expression pattern, which isessential for proper Isthmic Organizer function, is established during vertebratedevelopment. Because the secreted Wnt1 protein plays a prominent role in IsthmicOrganizer function, we focused in particular on the refinement of Wnt1gene expression in this context. We analyzed the dynamics of the corresponding murine gene regulatory network andthe related, diffusive signaling proteins using a macroscopic model for thebiological two-scale signaling process. Despite the discontinuity arisingfrom the sharp gene expression domain boundaries, we proved the existence ofunique, positive solutions for the partial differential equation system. Thisenabled the numerically and analytically analysis of the formation and stabilityof the expression pattern. Notably, the calculated expression domain ofWnt1 has no sharp boundary in contrast to experimental evidence. Wesubsequently propose a post-transcriptional regulatory mechanism for Wnt1miRNAs which yields the observed sharp expression domain boundaries. Weestablished a list of candidate miRNAs and confirmed their expression pattern byradioactive in situ hybridization. The miRNA miR-709 was identified as apotential regulator of Wnt1 mRNA, which was validated by luciferasesensor assays. In summary, our theoretical analysis of the gene expression pattern induction atthe mid-hindbrain boundary revealed the need to extend the model by an additionalWnt1 regulation. The developed macroscopic model of a two-scaleprocess facilitate the stringent analysis of other morphogen-based patterningprocesses.
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Sharpening of expression domains induced by transcription and microRNA regulation within a spatio-temporal model of mid-hindbrain boundary formation.
BMC systems biology, 2013Co-Authors: Sabrina Hock, Wolfgang Wurst, Nilima Prakash, Jan Hasenauer, Dominik Lutter, Dietrich Trümbach, Dominik M. Wittmann, Fabian J TheisAbstract:Background: The establishment of the mid-hindbrain region in vertebrates is mediated by the Isthmic Organizer, an embryonic secondary Organizer characterized by a well-defined pattern of locally restricted gene expression domains with sharply delimited boundaries. While the function of the Isthmic Organizer at the mid-hindbrain boundary has been subject to extensive experimental studies, it remains unclear how this well-defined spatial gene expression pattern, which is essential for proper Isthmic Organizer function, is established during vertebrate development. Because the secreted Wnt1 protein plays a prominent role in Isthmic Organizer function, we focused in particular on the refinement of Wnt1 gene expression in this context. Results: We analyzed the dynamics of the corresponding murine gene regulatory network and the related, diffusive signaling proteins using a macroscopic model for the biological two-scale signaling process. Despite the discontinuity arising from the sharp gene expression domain boundaries, we proved the existence of unique, positive solutions for the partial differential equation system. This enabled the numerically and analytically analysis of the formation and stability of the expression pattern. Notably, the calculated expression domain of Wnt1 has no sharp boundary in contrast to experimental evidence. We subsequently propose a post-transcriptional regulatory mechanism for Wnt1 miRNAs which yields the observed sharp expression domain boundaries. We established a list of candidate miRNAs and confirmed their expression pattern by radioactive in situ hybridization. The miRNA miR-709 was identified as a potential regulator of Wnt1 mRNA, which was validated by luciferase sensor assays. Conclusion: In summary, our theoretical analysis of the gene expression pattern induction at the mid-hindbrain boundary revealed the need to extend the model by an additional Wnt1 regulation. The developed macroscopic model of a two-scale process facilitate the stringent analysis of other morphogen-based patterning processes.
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FGF regulated gene-expression and neuronal differentiation in the developing midbrain-hindbrain region.
Developmental biology, 2006Co-Authors: Tomi Jukkola, Wolfgang Wurst, Laura Lahti, Thorsten Naserke, Juha PartanenAbstract:Abstract The neuroectodermal tissue close to the midbrain–hindbrain boundary (MHB) is an important secondary Organizer in the developing neural tube. This so-called Isthmic Organizer (IsO) secretes signaling molecules, such as fibroblast growth factors (FGFs), which regulate cellular survival, patterning and proliferation in the midbrain and rhombomere 1 (R1) of the hindbrain. We have previously shown that FGF-receptor 1 (FGFR1) is required for the normal development of this brain region in the mouse embryo. Here, we have compared the gene expression profiles of midbrain–R1 tissues from wild-type embryos and conditional Fgfr1 mutants, in which FGFR1 is inactivated in the midbrain and R1. Loss of Fgfr1 results in the downregulation of several genes expressed close to the midbrain–hindbrain boundary and in the disappearance of gene expression gradients in the midbrain and anterior hindbrain. Our screen identified several previously uncharacterized genes which may participate in the development of midbrain–R1 region. Our results also show altered neurogenesis in the midbrain and R1 of the Fgfr1 mutants. Interestingly, the neuronal progenitors in midbrain and R1 show different responses to the loss of signaling through FGFR1.
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the Isthmic Organizer signal fgf8 is required for cell survival in the prospective midbrain and cerebellum
Development, 2003Co-Authors: Salvador Martinez, Wolfgang Wurst, Gail R MartinAbstract:Numerous studies have demonstrated that the midbrain and cerebellum develop from a region of the early neural tube comprising two distinct territories known as the mesencephalon (mes) and rostral metencephalon (met; rhombomere 1), respectively. Development of the mes and met is thought to be regulated by molecules produced by a signaling center, termed the Isthmic Organizer (IsO), which is localized at the boundary between them. FGF8 and WNT1 have been implicated as key components of IsO signaling activity, and previous studies have shown that in Wnt1 -/- embryos, the mes/met is deleted by the 30 somite stage (∼E10) (McMahon, A. P. and Bradley, A. ([1990][1]) Cell 62, 1073-1085). We have studied the function of FGF8 in mouse mes/met development using a conditional gene inactivation approach. In our mutant embryos, Fgf8 expression was transiently detected, but then was eliminated in the mes/met by the 10 somite stage (∼E8.75). This resulted in a failure to maintain expression of Wnt1 as well as Fgf17, Fgf18 , and Gbx2 in the mes/met at early somite stages, and in the absence of the midbrain and cerebellum at E17.5. We show that a major cause of the deletion of these structures is ectopic cell death in the mes/met between the 7 and 30 somite stages. Interestingly, we found that the prospective midbrain was deleted at an earlier stage than the prospective cerebellum. We observed a remarkably similar pattern of cell death in Wnt1 null homozygotes, and also detected ectopic mes/met cell death in En1 null homozygotes. Our data show that Fgf8 is part of a complex gene regulatory network that is essential for cell survival in the mes/met. [1]: #ref-38
Salvador Martinez - One of the best experts on this subject based on the ideXlab platform.
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Fgf8-related secondary Organizers exert different polarizing planar instructions along the mouse anterior neural tube.
PloS one, 2012Co-Authors: Ivan Crespo-enriquez, Salvador Martinez, Juha Partanen, Diego EchevarriaAbstract:Early brain patterning depends on proper arrangement of positional information. This information is given by gradients of secreted signaling molecules (morphogens) detected by individual cells within the responding tissue, leading to specific fate decisions. Here we report that the morphogen FGF8 exerts initially a differential signal activity along the E9.5 mouse neural tube. We demonstrate that this polarizing activity codes by RAS-regulated ERK1/2 signaling and depends on the topographical location of the secondary Organizers: the Isthmic Organizer (IsO) and the anterior neural ridge (anr) but not on zona limitans intrathalamica (zli). Our results suggest that Sprouty2, a negative modulator of RAS/ERK pathway, is important for regulating Fgf8 morphogenetic signal activity by controlling Fgf8-induced signaling pathways and positional information during early brain development.
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Specific regions within the embryonic midbrain and cerebellum require different levels of FGF signaling during development
Development (Cambridge England), 2008Co-Authors: M. Albert Basson, Salvador Martinez, Alexandra L Joyner, Diego Echevarria, Anamaria Sudarov, Ivor Mason, Christina P. Ahn, Gail R MartinAbstract:Prospective midbrain and cerebellum formation are coordinated by FGF ligands produced by the Isthmic Organizer. Previous studies have suggested that midbrain and cerebellum development require different levels of FGF signaling. However, little is known about the extent to which specific regions within these two parts of the brain differ in their requirement for FGF signaling during embryogenesis. Here, we have explored the effects of inhibiting FGF signaling within the embryonic mouse midbrain (mesencephalon) and cerebellum (rhombomere 1) by misexpressing sprouty2 (Spry2) from an early stage. We show that such Spry2 misexpression moderately reduces FGF signaling, and that this reduction causes cell death in the anterior mesencephalon, the region furthest from the source of FGF ligands. Interestingly, the remaining mesencephalon cells develop into anterior midbrain, indicating that a low level of FGF signaling is sufficient to promote only anterior midbrain development. Spry2 misexpression also affects development of the vermis, the part of the cerebellum that spans the midline. We found that, whereas misexpression of Spry2 alone caused loss of the anterior vermis, reducing FGF signaling further, by decreasing Fgf8 gene dose, resulted in loss of the entire vermis. Our data suggest that cell death is not responsible for vermis loss, but rather that it fails to develop because reducing FGF signaling perturbs the balance between vermis and roof plate development in rhombomere 1. We suggest a molecular explanation for this phenomenon by providing evidence that FGF signaling functions to inhibit the BMP signaling that promotes roof plate development.
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positional regulation of pax2 expression pattern in mesencephalic and diencephalic alar plate
Neuroscience, 2006Co-Authors: Claudia Vieira, Raquel Garcialopez, Salvador MartinezAbstract:Regionalization of the neural tube is a fundamental event in the development of the CNS. The Isthmic Organizer controls the development of the mesencephalic-rhombencephalic junction by means of fibroblast growth factor 8 (Fgf8) expression. The transcription factor paired box 2 (Pax2) is expressed early in the midbrain and is later progressively restricted to the mid-hindbrain region, playing an important role in the development of the mesencephalon and the cerebellum. In this study, by implanting Fgf8-beads in the chick neural tube, we show that Fgf8 induces a heterogeneous pattern of Pax2 expression in the diencephalon. To explore the mechanisms controlling this asymmetric induction and the down-regulation of Pax2 in the anterior mesencephalon we performed antero-posterior inversions of diencephalic and/or mesencephalic neuroepithelium, with or without Fgf8-bead implantation. We show that anterior factors do not play a role in Pax2 regionalization, while posterior factors could explain these expression patterns. We conclude that the anterior mesencephalon and the diencephalon are able to retain or activate Pax2 expression under caudal influences, and to develop as a tectal structure at later developmental stages.
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Mkp3 is a negative feedback modulator of Fgf8 signaling in the mammalian Isthmic Organizer.
Developmental biology, 2005Co-Authors: Diego Echevarria, Salvador Martinez, Sara Marques, Vera Lucas-teixeira, José António BeloAbstract:The pivotal mechanisms that govern the correct patterning and regionalization of the distinct areas of the mammalian CNS are driven by key molecules that emanate from the so-called secondary Organizers at neural plate and tube stages. FGF8 is the candidate morphogenetic molecule to pattern the mesencephalon and rhombencephalon in the Isthmic Organizer (IsO). Recognizable relevance has been given to the intracellular pathways by which Fgf8 is regulated and modulated. In chick limb bud development, a dual mitogen-activated protein kinase phosphatase-3 (Mkp3) plays a role as a negative feedback modulator of Fgf8 signaling. We have investigated the role of Mkp3 and its functional relationship with the Fgf8 signaling pathway in the mouse IsO using gene transfer microelectroporation assays and protein-soaked bead experiments. Here, we demonstrate that MKP3 has a negative feedback action on the MAPK/ERK-mediated FGF8 pathway in the mouse neuroepithelium.
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Modulation of Fgf8 activity during vertebrate brain development.
Brain research. Brain research reviews, 2005Co-Authors: Diego Echevarria, José António Belo, Salvador MartinezAbstract:In recent years much emphasis has been placed on investigation of the precise control of FGF signaling during brain development. Such control is achieved in part by regulatory elements that determine the domains and levels of expression of genes coding for the diverse FGF ligands via specific molecular signaling pathways. There is new knowledge on the operation of such mechanisms in regions of the neural tube involved in the correct patterning of adjacent territories (known as secondary Organizers of neural tube pattern). In the present minireview we intend to summarize recent evidence and emerging conclusions on potent modulators that govern the activity of Fgf8 signals in the developing vertebrate brain, focusing our attention on the best known secondary Organizer, the Isthmic Organizer.
Alexandra L Joyner - One of the best experts on this subject based on the ideXlab platform.
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the engrailed homeobox genes determine the different foliation patterns in the vermis and hemispheres of the mammalian cerebellum
Development, 2010Co-Authors: Yulan Cheng, Kamila U Szulc, Daniel H Turnbull, Anamaria Sudarov, Sema K Sgaier, Daniel Stephen, Alexandra L JoynerAbstract:Little is known about the genetic pathways and cellular processes responsible for regional differences in cerebellum foliation, which interestingly are accompanied by regionally distinct afferent circuitry. We have identified the Engrailed (En) homeobox genes as being crucial to producing the distinct medial vermis and lateral hemisphere foliation patterns in mammalian cerebella. By producing a series of temporal conditional mutants in En1 and/or En2, we demonstrate that both En genes are required to ensure that folia exclusive to the vermis or hemispheres form in the appropriate mediolateral position. Furthermore, En1/En2 continue to regulate foliation after embryonic day 14, at which time Fgf8 Isthmic Organizer activity is complete and the major output cells of the cerebellar cortex have been specified. Changes in spatially restricted gene expression occur prior to foliation in mutants, and foliation is altered from the onset and is accompanied by changes in the thickness of the layer of proliferating granule cell precursors. In addition, the positioning and timing of fissure formation are altered. Thus, the En genes represent a new class of genes that are fundamental to patterning cerebellum foliation throughout the mediolateral axis and that act late in development.
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The duration of Fgf8 Isthmic Organizer expression is key to patterning different tectal-isthmo-cerebellum structures.
Development (Cambridge England), 2009Co-Authors: Tatsuya Sato, Alexandra L JoynerAbstract:The Isthmic Organizer and its key effector molecule, fibroblast growth factor 8 (Fgf8), have been cornerstones in studies of how organizing centers differentially pattern tissues. Studies have implicated different levels of Fgf8 signaling from the mid/hindbrain boundary (isthmus) as being responsible for induction of different structures within the tectal-isthmo-cerebellum region. However, the role of Fgf8 signaling for different durations in patterning tissues has not been studied. To address this, we conditionally ablated Fgf8 in the isthmus and uncovered that prolonged expression of Fgf8 is required for the structures found progressively closer to the isthmus to form. We found that cell death cannot be the main factor accounting for the loss of brain structures near the isthmus, and instead demonstrate that tissue transformation underlies the observed phenotypes. We suggest that the remaining Fgf8 and Fgf17 signaling in our temporal Fgf8 conditional mutants is sufficient to ensure survival of most midbrain/hindbrain cells near the isthmus. One crucial role for sustained Fgf8 function is in repressing Otx2 in the hindbrain, thereby allowing the isthmus and cerebellum to form. A second requirement for sustained Fgf8 signaling is to induce formation of a posterior tectum. Finally, Fgf8 is also required to maintain the borders of expression of a number of key genes involved in tectal-isthmo-cerebellum development. Thus, the duration as well as the strength of Fgf8 signaling is key to patterning of the mid/hindbrain region. By extrapolation, the length of Fgf8 expression could be crucial to Fgf8 function in other embryonic Organizers.
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Specific regions within the embryonic midbrain and cerebellum require different levels of FGF signaling during development
Development (Cambridge England), 2008Co-Authors: M. Albert Basson, Salvador Martinez, Alexandra L Joyner, Diego Echevarria, Anamaria Sudarov, Ivor Mason, Christina P. Ahn, Gail R MartinAbstract:Prospective midbrain and cerebellum formation are coordinated by FGF ligands produced by the Isthmic Organizer. Previous studies have suggested that midbrain and cerebellum development require different levels of FGF signaling. However, little is known about the extent to which specific regions within these two parts of the brain differ in their requirement for FGF signaling during embryogenesis. Here, we have explored the effects of inhibiting FGF signaling within the embryonic mouse midbrain (mesencephalon) and cerebellum (rhombomere 1) by misexpressing sprouty2 (Spry2) from an early stage. We show that such Spry2 misexpression moderately reduces FGF signaling, and that this reduction causes cell death in the anterior mesencephalon, the region furthest from the source of FGF ligands. Interestingly, the remaining mesencephalon cells develop into anterior midbrain, indicating that a low level of FGF signaling is sufficient to promote only anterior midbrain development. Spry2 misexpression also affects development of the vermis, the part of the cerebellum that spans the midline. We found that, whereas misexpression of Spry2 alone caused loss of the anterior vermis, reducing FGF signaling further, by decreasing Fgf8 gene dose, resulted in loss of the entire vermis. Our data suggest that cell death is not responsible for vermis loss, but rather that it fails to develop because reducing FGF signaling perturbs the balance between vermis and roof plate development in rhombomere 1. We suggest a molecular explanation for this phenomenon by providing evidence that FGF signaling functions to inhibit the BMP signaling that promotes roof plate development.
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New regulatory interactions and cellular responses in the Isthmic Organizer region revealed by altering Gbx2 expression.
Development (Cambridge England), 2005Co-Authors: Zhimin Lao, Alexandra L JoynerAbstract:The mouse homeobox gene Gbx2 is first expressed throughout the posterior region of the embryo during gastrulation, and becomes restricted to rhombomeres 1-3 (r1-3) by embryonic day 8.5 (E8.5). Previous studies have shown that r1-3 do not develop in Gbx2 mutants and that there is an early caudal expansion of the midbrain gene Otx2 to the anterior border of r4. Furthermore, expression of Wnt1 and Fgf8 , two crucial components of the Isthmic Organizer, is no longer segregated to adjacent domains in Gbx2 mutants. In this study, we extend the phenotypic analysis of Gbx2 mutants by showing that Gbx2 is not only required for development of r1-3, but also for normal gene expression in r4-6. To determine whether Gbx2 can alter hindbrain development, we generated Hoxb1-Gbx2 ( HG ) transgenic mice in which Gbx2 is ectopically expressed in r4. We show that Gbx2 is not sufficient to induce r1-3 development in r4. To test whether an Otx2/Gbx2 interface can induce r1-3 development, we introduced the HG transgene onto a Gbx2 -null mutant background and recreated a new Otx2/Gbx2 border in the anterior hindbrain. Development of r3, but not r1 and r2, is rescued in Gbx2 –/– ; HG embryos. In addition, the normal spatial relationship of Wnt1 and Fgf8 is established at the new Otx2/Gbx2 border, demonstrating that an interaction between Otx2 and Gbx2 is sufficient to produce the normal pattern of Wnt1 and Fgf8 expression. However, the expression domains of Fgf8 and Spry1, a downstream target of Fgf8, are greatly reduced in mid/hindbrain junction area of Gbx2 –/– ; HG embryos and the posterior midbrain is truncated because of abnormal cell death. Interestingly, we show that increased cell death and a partial loss of the midbrain are associated with increased expression of Fgf8 and Spry1 in Gbx2 conditional mutants that lack Gbx2 in r1 after E9.0. These results together suggest that cell survival in the posterior midbrain is positively or negatively regulated by Fgf8, depending on Fgf8 expression level. Our studies provide new insights into the regulatory interactions that maintain Isthmic Organizer gene expression and the consequences of altered levels of Organizer gene expression on cell survival.
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Cell behaviors and genetic lineages of the mesencephalon and rhombomere 1.
Neuron, 2004Co-Authors: Mark Zervas, Sandrine Millet, Sohyun Ahn, Alexandra L JoynerAbstract:Brain structures derived from the mesencephalon (mes) and rhombomere 1 (r1) modulate distinct motor and sensory modalities. The precise origin and cellular behaviors underpinning the cytoarchitectural organization of the mes and r1, however, are unknown. Using a novel inducible genetic fate mapping approach in mouse, we determined the fate and lineage relationships of mes/r1 cells with fine temporal and spatial resolution. We demonstrate that the mes and r1 are neuromeres that along with the Isthmic Organizer are partitioned along the anterior-posterior axis by lineage restriction boundaries established sequentially between E8.5 and E9.5. Furthermore, a small group of cells originating from the most posterior mes exhibit anterior intracompartmental expansion and contribute throughout the inferior colliculus. Finally, we also uncovered transient and differential genetic lineages of ventral midbrain dopaminergic and ventral hindbrain serotonergic neuronal precursors with respect to Wnt1 and Gli1 expression.
Carolina Parada - One of the best experts on this subject based on the ideXlab platform.
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All-trans retinol and retinol-binding protein from embryonic cerebrospinal fluid exhibit dynamic behaviour during early central nervous system development.
Neuroreport, 2008Co-Authors: Carolina Parada, A. Gato, David BuenoAbstract:: Embryonic cerebrospinal fluid (E-CSF) is involved in the regulation of survival, proliferation and neurogenesis of neuroectodermal progenitor cells, as well as in the control of mesencephalic gene expression in collaboration with the Isthmic Organizer. Recently, we showed the presence of retinol-binding protein (RBP) within the E-CSF proteome. RBP is an all-trans retinol carrier, a molecule that can be metabolized into retinoic acid, a morphogen involved in central nervous system (CNS) morphogenesis and patterning. Here we demonstrate the presence of all-trans retinol within the E-CSF and analyse the dynamics of RBP and all-trans retinol within this fluid, as well as the expression of retinoic acid-synthesizing enzymes during early CNS development. Our results suggest a relationship between the dynamics of these molecules and the early events of CNS patterning.
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All-trans retinol and retinol-binding protein from embryonic cerebrospinal £uid exhibit dynamic behaviour during early central nervous system development
Developmental Neuroscience, 2008Co-Authors: Carolina Parada, Ángel Luis Gato Casado, David Bueno I TorrensAbstract:Embryonic cerebrospinal £uid (E-CSF) is involved in the regulation of survival, proliferation and neurogenesis of neuroectodermal progenitor cells, as well as in the control of mesencephalic gene expression in collaboration with the Isthmic Organizer. Recently, we showed the presence of retinol-binding protein (RBP) within the E-CSF proteome. RBP is an all-trans retinol carrier, a molecule that can be metabolized into retinoic acid, a morphogen involved in central nervous system (CNS) morphogenesis and patterning. Here we demonstrate the presence of all-trans retinol within the E-CSF and analyse the dynamics of RBP and all-trans retinol within this £uid, as well as the expression of retinoic acid-synthesizing enzymes during early CNS development. Our results suggest a relationship between the dynamics of these molecules and the early events of CNS patterning. NeuroReport 19:945^950 c 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins.
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Embryonic cerebrospinal fluid collaborates with the Isthmic Organizer to regulate mesencephalic gene expression.
Journal of neuroscience research, 2005Co-Authors: Carolina Parada, David Bueno, C. Martín, M.i. Alonso, J.a. Moro, A. GatoAbstract:Early in development, the behavior of neuroepithelial cells is controlled by several factors acting in a developmentally regulated manner. Recently it has been shown that diffusible factors contained within embryonic cerebrospinal fluid (CSF) promote neuroepithelial cell survival, proliferation, and neurogenesis in mesencephalic explants lacking any known organizing center. In this paper, we show that mesencephalic and mesencephalic + Isthmic Organizer explants cultured only with basal medium do not express the typically expressed mesencephalic or Isthmic Organizer genes analyzed (otx2 and fgf8, respectively) and that mesencephalic explants cultured with embryonic CSF-supplemented medium do effect such expression, although they exhibit an altered pattern of gene expression, including ectopic shh expression domains. Other trophic sources that are able to maintain normal neuroepithelial cell behavior, i.e., fibroblast growth factor-2, fail to activate this ectopic shh expression. Conversely, the expression pattern of the analyzed genes in mesencephalic + Isthmic Organizer explants cultured with embryonic cerebrospinal fluid-supplemented medium mimics the pattern for control embryos developed in ovo. We demonstrate that embryonic CSF collaborates with the Isthmic Organizer in regulation of the expression pattern of some characteristic neuroectodermal genes during early stages of central nervous system (CNS) development, and we suggest that this collaboration is not restricted to the maintenance of neuroepithelial cell survival. Data reported in this paper corroborate the hypothesis that factors contained within embryonic CSF contribute to the patterning of the CNS during early embryonic development. © 2005 Wiley-Liss, Inc.
Fabian J Theis - One of the best experts on this subject based on the ideXlab platform.
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Sharpening of expression domains induced by transcription and microRNA regulationwithin a spatio-temporal model of mid-hindbrain boundary formation
BMC Systems Biology, 2013Co-Authors: Sabrina Hock, Wolfgang Wurst, Nilima Prakash, Jan Hasenauer, Dominik Wittmann, Dominik Lutter, Dietrich Trümbach, Fabian J TheisAbstract:Background The establishment of the mid-hindbrain region in vertebrates is mediated by theIsthmic Organizer, an embryonic secondary Organizer characterized by awell-defined pattern of locally restricted gene expression domains with sharplydelimited boundaries. While the function of the Isthmic Organizer at themid-hindbrain boundary has been subject to extensive experimental studies, itremains unclear how this well-defined spatial gene expression pattern, which isessential for proper Isthmic Organizer function, is established during vertebratedevelopment. Because the secreted Wnt1 protein plays a prominent role in IsthmicOrganizer function, we focused in particular on the refinement of Wnt1 gene expression in this context. Results We analyzed the dynamics of the corresponding murine gene regulatory network andthe related, diffusive signaling proteins using a macroscopic model for thebiological two-scale signaling process . Despite the discontinuity arisingfrom the sharp gene expression domain boundaries, we proved the existence ofunique, positive solutions for the partial differential equation system. Thisenabled the numerically and analytically analysis of the formation and stabilityof the expression pattern. Notably, the calculated expression domain of Wnt1 has no sharp boundary in contrast to experimental evidence. Wesubsequently propose a post-transcriptional regulatory mechanism for Wnt1 miRNAs which yields the observed sharp expression domain boundaries. Weestablished a list of candidate miRNAs and confirmed their expression pattern byradioactive in situ hybridization. The miRNA miR-709 was identified as apotential regulator of Wnt1 mRNA, which was validated by luciferasesensor assays. Conclusion In summary, our theoretical analysis of the gene expression pattern induction atthe mid-hindbrain boundary revealed the need to extend the model by an additional Wnt1 regulation. The developed macroscopic model of a two-scaleprocess facilitate the stringent analysis of other morphogen-based patterningprocesses.
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Sharpening of expression domains induced by transcription and microRNA regulation within a spatio-temporal model of mid-hindbrain boundary formation.
BMC systems biology, 2013Co-Authors: Sabrina Hock, Wolfgang Wurst, Nilima Prakash, Jan Hasenauer, Dominik Lutter, Dietrich Trümbach, Dominik M. Wittmann, Fabian J TheisAbstract:The establishment of the mid-hindbrain region in vertebrates is mediated by theIsthmic Organizer, an embryonic secondary Organizer characterized by awell-defined pattern of locally restricted gene expression domains with sharplydelimited boundaries. While the function of the Isthmic Organizer at themid-hindbrain boundary has been subject to extensive experimental studies, itremains unclear how this well-defined spatial gene expression pattern, which isessential for proper Isthmic Organizer function, is established during vertebratedevelopment. Because the secreted Wnt1 protein plays a prominent role in IsthmicOrganizer function, we focused in particular on the refinement of Wnt1gene expression in this context. We analyzed the dynamics of the corresponding murine gene regulatory network andthe related, diffusive signaling proteins using a macroscopic model for thebiological two-scale signaling process. Despite the discontinuity arisingfrom the sharp gene expression domain boundaries, we proved the existence ofunique, positive solutions for the partial differential equation system. Thisenabled the numerically and analytically analysis of the formation and stabilityof the expression pattern. Notably, the calculated expression domain ofWnt1 has no sharp boundary in contrast to experimental evidence. Wesubsequently propose a post-transcriptional regulatory mechanism for Wnt1miRNAs which yields the observed sharp expression domain boundaries. Weestablished a list of candidate miRNAs and confirmed their expression pattern byradioactive in situ hybridization. The miRNA miR-709 was identified as apotential regulator of Wnt1 mRNA, which was validated by luciferasesensor assays. In summary, our theoretical analysis of the gene expression pattern induction atthe mid-hindbrain boundary revealed the need to extend the model by an additionalWnt1 regulation. The developed macroscopic model of a two-scaleprocess facilitate the stringent analysis of other morphogen-based patterningprocesses.
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Sharpening of expression domains induced by transcription and microRNA regulation within a spatio-temporal model of mid-hindbrain boundary formation.
BMC systems biology, 2013Co-Authors: Sabrina Hock, Wolfgang Wurst, Nilima Prakash, Jan Hasenauer, Dominik Lutter, Dietrich Trümbach, Dominik M. Wittmann, Fabian J TheisAbstract:Background: The establishment of the mid-hindbrain region in vertebrates is mediated by the Isthmic Organizer, an embryonic secondary Organizer characterized by a well-defined pattern of locally restricted gene expression domains with sharply delimited boundaries. While the function of the Isthmic Organizer at the mid-hindbrain boundary has been subject to extensive experimental studies, it remains unclear how this well-defined spatial gene expression pattern, which is essential for proper Isthmic Organizer function, is established during vertebrate development. Because the secreted Wnt1 protein plays a prominent role in Isthmic Organizer function, we focused in particular on the refinement of Wnt1 gene expression in this context. Results: We analyzed the dynamics of the corresponding murine gene regulatory network and the related, diffusive signaling proteins using a macroscopic model for the biological two-scale signaling process. Despite the discontinuity arising from the sharp gene expression domain boundaries, we proved the existence of unique, positive solutions for the partial differential equation system. This enabled the numerically and analytically analysis of the formation and stability of the expression pattern. Notably, the calculated expression domain of Wnt1 has no sharp boundary in contrast to experimental evidence. We subsequently propose a post-transcriptional regulatory mechanism for Wnt1 miRNAs which yields the observed sharp expression domain boundaries. We established a list of candidate miRNAs and confirmed their expression pattern by radioactive in situ hybridization. The miRNA miR-709 was identified as a potential regulator of Wnt1 mRNA, which was validated by luciferase sensor assays. Conclusion: In summary, our theoretical analysis of the gene expression pattern induction at the mid-hindbrain boundary revealed the need to extend the model by an additional Wnt1 regulation. The developed macroscopic model of a two-scale process facilitate the stringent analysis of other morphogen-based patterning processes.
