scholarly journals Cre/lox-controlled spatio-temporal perturbation of FGF signaling in zebrafish

2018 ◽  
Author(s):  
Lucia Kirchgeorg ◽  
Anastasia Felker ◽  
Elena Chiavacci ◽  
Christian Mosimann

Fibroblast Growth Factor (FGF) signaling guides multiple developmental processes including body axis formation and specific cell fate patterning. In zebrafish, genetic mutants and chemical perturbations affecting FGF signaling have uncovered key developmental processes; however, these approaches cause embryo-wide FGF signaling perturbations, rendering assessment of cell-autonomous versus non-autonomous requirements for FGF signaling in individual processes difficult. Here, we created the novel transgenic line fgfr1-dn-cargo, encoding dominant-negative Fgfr1 with fluorescent tag under combined Cre/lox and heatshock control to provide spatio-temporal perturbation of FGF signaling. Validating efficient perturbation of FGF signaling by fgfr1-dn-cargo primed with ubiquitous CreERT2, we established that primed, heatshock-induced fgfr1-dn-cargo behaves akin to pulsed treatment with the FGFR inhibitor SU5402. Priming fgfr1-dn-cargo with CreERT2 in the lateral plate mesoderm, we observed selective cardiac and pectoral fin phenotypes without drastic impact on overall embryo patterning. Harnessing lateral plate mesoderm-specific FGF inhibition, we recapitulated the cell-autonomous and temporal requirement for FGF signaling in pectoral fin outgrow, as previously hypothesized from pan-embryonic FGF inhibition. Altogether, our results establish fgfr1-dn-cargo as a genetic tool to define the spatio-temporal requirements for FGF signaling in zebrafish.

1999 ◽  
Vol 19 (2) ◽  
pp. 1427-1437 ◽  
Author(s):  
Monica A. Torres ◽  
Hagit Eldar-Finkelman ◽  
Edwin G. Krebs ◽  
Randall T. Moon

ABSTRACT β-Catenin is a multifunctional protein that binds cadherins at the plasma membrane, HMG box transcription factors in the nucleus, and several cytoplasmic proteins that are involved in regulating its stability. In developing embryos and in some human cancers, the accumulation of β-catenin in the cytoplasm and subsequently the nuclei of cells may be regulated by the Wnt-1 signaling cascade and by glycogen synthase kinase 3 (GSK-3). This has increased interest in regulators of both GSK-3 and β-catenin. Searching for kinase activities able to phosphorylate the conserved, inhibitory-regulatory GSK-3 residue serine 9, we found p90 rsk to be a potential upstream regulator of GSK-3. Overexpression of p90 rsk in Xenopus embryos leads to increased steady-state levels of total β-catenin but not of the free soluble protein. Instead, p90 rsk overexpression increases the levels of β-catenin in a cell fraction containing membrane-associated cadherins. Consistent with the lack of elevation of free β-catenin levels, ectopic p90 rsk was unable to rescue dorsal cell fate in embryos ventralized by UV irradiation. We show that p90 rsk is a downstream target of fibroblast growth factor (FGF) signaling during early Xenopus development, since ectopic FGF signaling activates both endogenous and overexpressed p90 rsk . Moreover, overexpression of a dominant negative FGF receptor, which blocks endogenous FGF signaling, leads to decreased p90 rsk kinase activity. Finally, we report that FGF inhibits endogenous GSK-3 activity inXenopus embryos. We hypothesize that FGF and p90 rsk play heretofore unsuspected roles in modulating GSK-3 and β-catenin.


Development ◽  
1997 ◽  
Vol 124 (9) ◽  
pp. 1631-1642 ◽  
Author(s):  
P.P. Tam ◽  
M. Parameswaran ◽  
S.J. Kinder ◽  
R.P. Weinberger

The cardiogenic potency of cells in the epiblast of the early primitive-streak stage (early PS) embryo was tested by heterotopic transplantation. The results of this study show that cells in the anterior and posterior epiblast of the early PS-stage embryos have similar cardiogenic potency, and that they differentiated to heart cells after they were transplanted directly to the heart field of the late PS embryo. That the epiblast cells can acquire a cardiac fate without any prior act of ingression through the primitive streak or movement within the mesoderm suggests that neither morphogenetic event is critical for the specification of the cardiogenic fate. The mesodermal cells that have recently ingressed through the primitive streak can express a broad cell fate that is characteristic of the pre-ingressed cells in the host when they were returned to the epiblast. However, mesoderm cells that have ingressed through the primitive streak did not contribute to the lateral plate mesoderm after transplantation back to the epiblast, implying that some restriction of lineage potency may have occurred during ingression. Early PS stage epiblast cells that were transplanted to the epiblast of the mid PS host embryos colonised the embryonic mesoderm but not the extraembryonic mesoderm. This departure from the normal cell fate indicates that the allocation of epiblast cells to the mesodermal lineages is dependent on the timing of their recruitment to the primitive streak and the morphogenetic options that are available to the ingressing cells at that instance.


2007 ◽  
Vol 303 (2) ◽  
pp. 527-535 ◽  
Author(s):  
Takashi Wakahara ◽  
Naoki Kusu ◽  
Hajime Yamauchi ◽  
Ikuo Kimura ◽  
Morichika Konishi ◽  
...  

Development ◽  
2000 ◽  
Vol 127 (12) ◽  
pp. 2573-2582 ◽  
Author(s):  
D. Yelon ◽  
B. Ticho ◽  
M.E. Halpern ◽  
I. Ruvinsky ◽  
R.K. Ho ◽  
...  

The precursors of several organs reside within the lateral plate mesoderm of vertebrate embryos. Here, we demonstrate that the zebrafish hands off locus is essential for the development of two structures derived from the lateral plate mesoderm - the heart and the pectoral fin. hands off mutant embryos have defects in myocardial development from an early stage: they produce a reduced number of myocardial precursors, and the myocardial tissue that does form is improperly patterned and fails to maintain tbx5 expression. A similar array of defects is observed in the differentiation of the pectoral fin mesenchyme: small fin buds form in a delayed fashion, anteroposterior patterning of the fin mesenchyme is absent and tbx5 expression is poorly maintained. Defects in these mesodermal structures are preceded by the aberrant morphogenesis of both the cardiogenic and forelimb-forming regions of the lateral plate mesoderm. Molecular analysis of two hands off alleles indicates that the hands off locus encodes the bHLH transcription factor Hand2, which is expressed in the lateral plate mesoderm starting at the completion of gastrulation. Thus, these studies reveal early functions for Hand2 in several cellular processes and highlight a genetic parallel between heart and forelimb development.


2022 ◽  
Author(s):  
Axel H Newton ◽  
Sarah M Williams ◽  
Andrew T Major ◽  
Craig A Smith

The lateral plate mesoderm (LPM) is a transient embryonic tissue that gives rise to a diverse range of mature cell types, including the cardiovascular system, the urogenital system, endoskeleton of the limbs, and mesenchyme of the gut. While the genetic processes that drive development of these tissues are well defined, the early cell fate choices underlying LPM development and specification are poorly understood. In this study, we utilize single-cell transcriptomics to define cell lineage specification during development of the anterior LPM and the forelimb field in the chicken embryo. We identify the molecular pathways directing differentiation of the aLPM towards a somatic or splanchnic cell fate, and subsequent emergence of the forelimb mesenchyme. We establish the first transcriptional atlas of progenitor, transitional and mature cell types throughout the early forelimb field and uncover the global signalling pathways which are active during LPM differentiation and forelimb initiation. Specification of the somatic and splanchnic LPM from undifferentiated mesoderm utilizes distinct signalling pathways and involves shared repression of early mesodermal markers, followed by activation of lineage-specific gene modules. We identify rapid activation of the transcription factor TWIST1 in the somatic LPM preceding activation of known limb initiation genes, such as TBX5, which plays a likely role in epithelial-to-mesenchyme transition of the limb bud mesenchyme. Furthermore, development of the somatic LPM and limb is dependent on ectodermal BMP signalling, where BMP antagonism reduces expression of key somatic LPM and limb genes to inhibit formation of the limb bud mesenchyme. Together, these findings provide new insights into molecular mechanisms that drive fate cell choices during specification of the aLPM and forelimb initiation.


Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1095-1101 ◽  
Author(s):  
G.N. Serbedzija ◽  
J.N. Chen ◽  
M.C. Fishman

In many vertebrates, removal of early embryonic heart precursors can be repaired, leaving the heart and embryo without visible deficit. One possibility is that this ‘regulation’ involves a cell fate switch whereby cells, perhaps in regions surrounding normal progenitors, are redirected to the heart cell fate. However, the lineage and spatial relationships between cells that are normal heart progenitors and those that can assume that role after injury are not known, nor are their molecular distinctions. We have adapted a laser-activated technique to label single or small patches of cells in the lateral plate mesoderm of the zebrafish and to track their subsequent lineage. We find that the heart precursor cells are clustered in a region adjacent to the prechordal plate, just anterior to the notochord tip. Complete unilateral ablation of all heart precursors with a laser does not disrupt heart development, if performed before the 18-somite stage. By combining extirpation of the heart precursors with cell labeling, we find that cells anterior to the normal cardiogenic compartments constitute the source of regulatory cells that compensate for the loss of the progenitors. One of the earliest embryonic markers of the premyocardial cells is the divergent homeodomain gene, Nkx2.5. Interestingly, normal cardiogenic progenitors derive from only the anterior half of the Nkx2.5-expressing region in the lateral plate mesoderm. The posterior half, adjacent to the notochord, does not include cardiac progenitors and the posterior Nkx2.5-expressing cells do not contribute to the heart, even after ablation of the normal cardiogenic region. The cells that can acquire a cardiac cell fate after injury to the normal progenitors also reside near the prechordal plate, but anterior to the Nkx2.5-expressing domain. Normally they give rise to head mesenchyme. They share with cardiac progenitors early expression of GATA 4. The location of the different elements of the cardiac field, and their response to injury, suggests that the prechordal plate supports and/or the notochord suppresses the cardiac fate.


1998 ◽  
Vol 18 (9) ◽  
pp. 4986-4993 ◽  
Author(s):  
Jin-Hong Chang ◽  
Joanne C. Pratt ◽  
Sansana Sawasdikosol ◽  
Rosana Kapeller ◽  
Steven J. Burakoff

ABSTRACT The Rho family of small GTP-binding proteins is involved in the regulation of cytoskeletal structure, gene transcription, specific cell fate development, and transformation. We demonstrate in this report that overexpression of an activated form of Rho enhances AP-1 activity in Jurkat T cells in the presence of phorbol myristate acetate (PMA), but activated Rho (V14Rho) has little or no effect on NFAT, Oct-1, and NF-κB enhancer element activities under similar conditions. Overexpression of a V14Rho construct incapable of membrane localization (CAAX deleted) abolishes PMA-induced AP-1 transcriptional activation. The effect of Rho on AP-1 is independent of the mitogen-activated protein kinase pathway, as a dominant-negative MEK and a MEK inhibitor (PD98059) did not affect Rho-induced AP-1 activity. V14Rho binds strongly to protein kinase Cα (PKCα) in vivo; however, deletion of the CAAX site on V14Rho severely diminished this association. Evidence for a role for PKCα as an effector of Rho was obtained by the observation that coexpression of the N-terminal domain of PKCα blocked the effects of activated Rho plus PMA on AP-1 transcriptional activity. These data suggest that Rho potentiates AP-1 transcription during T-cell activation.


Cancers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2407
Author(s):  
Ruicen He ◽  
Arthur Dantas ◽  
Karl Riabowol

Acetylation of histones is a key epigenetic modification involved in transcriptional regulation. The addition of acetyl groups to histone tails generally reduces histone-DNA interactions in the nucleosome leading to increased accessibility for transcription factors and core transcriptional machinery to bind their target sequences. There are approximately 30 histone acetyltransferases and their corresponding complexes, each of which affect the expression of a subset of genes. Because cell identity is determined by gene expression profile, it is unsurprising that the HATs responsible for inducing expression of these genes play a crucial role in determining cell fate. Here, we explore the role of HATs in the maintenance and differentiation of various stem cell types. Several HAT complexes have been characterized to play an important role in activating genes that allow stem cells to self-renew. Knockdown or loss of their activity leads to reduced expression and or differentiation while particular HATs drive differentiation towards specific cell fates. In this study we review functions of the HAT complexes active in pluripotent stem cells, hematopoietic stem cells, muscle satellite cells, mesenchymal stem cells, neural stem cells, and cancer stem cells.


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