In the Supporting Information section of the article, Figures S2, S5, and S6 do not appear properly. S2: http://www.plosone.org/corrections/pone.0052781.s002.cn.tif S5: ...http://www.plosone.org/corrections/pone.0052781.s005.cn.tif S6: http://www.plosone.org/corrections/pone.0052781.s006.cn.tif Citation: Casanova JC, Badia-Careaga C, Uribe V, Sanz-Ezquerro JJ (2013) Correction: Bambi and Sp8 Expression Mark Digit Tips and Their Absence Shows That Chick Wing Digits 2 and 3 Are Truncated.
Mitogen- and Stress-activated Kinase (MSK) 1 is a nuclear protein, activated by p38α Mitogen-Activated Kinase (MAPK) and extracellular signal-regulated kinase (ERK1/2), that modulate the production ...of certain cytokines in macrophages. Using knockout cells and specific kinase inhibitors, we show that, besides p38α and ERK1/2, another p38MAPK, p38δ, mediates MSK phosphorylation and activation, in LPS-stimulated macrophages. Additionally, recombinant MSK1 was phosphorylated and activated by recombinant p38δ, to the same extent than by p38α, in
experiments. Moreover, the phosphorylation of the transcription factors CREB and ATF1, that are MSK physiological substrates, and the expression of the CREB-dependent gene encoding DUSP1, were impaired in p38δ-deficient macrophages. Also, the transcription of IL-1Ra mRNA, that is MSK-dependent, was reduced. Our results indicate that MSK activation can be one possible mechanism by which p38δ regulates the production of a variety of inflammatory molecules involved in immune innate response.
Background: The importance of endogenous antagonists in intracellular signal transduction pathways is becoming increasingly recognized. There is evidence in cultured mammalian cells that Pyst1/MKP3, ...a dual specificity protein phosphatase, specifically binds to and inactivates ERK1/2 mitogen-activated protein kinases (MAPKs). High-level Pyst1/Mkp3 expression has recently been found at many sites of known FGF signaling in mouse embryos, but the significance of this association and its function are not known.
Results: We have cloned chicken Pyst1/Mkp3 and show that high-level expression in neural plate correlates with active MAPK. We show that FGF signaling regulates Pyst1 expression in developing neural plate and limb bud by ablating and/or transplanting tissue sources of FGFs and by applying FGF protein or a specific FGFR inhibitor (SU5402). We further show by applying a specific MAP kinase kinase inhibitor (PD184352) that Pyst1 expression is regulated via the MAPK cascade. Overexpression of Pyst1 in chick embryos reduces levels of activated MAPK in neural plate and alters its morphology and retards limb bud outgrowth.
Conclusions: Pyst1 is an inducible antagonist of FGF signaling in embryos and acts in a negative feedback loop to regulate the activity of MAPK. Our results demonstrate both the importance of MAPK signaling in neural induction and limb bud outgrowth and the critical role played by dual specificity MAP kinase phosphatases in regulating developmental outcomes in vertebrates.
The apical ectodermal ridge (AER) is a specialized epithelium located at the distal edge of the limb bud that directs outgrowth along the proximodistal axis. Although the molecular basis for its ...function is well known, the cellular mechanisms that lead to its maturation are not fully understood. Here, we show that Arid3b, a member of the ARID family of transcriptional regulators, is expressed in the AER in mouse and chick embryos, and that interference with its activity leads to aberrant AER development, in which normal structure is not achieved. This happens without alterations in cell numbers or gene expression in main signalling pathways. Cells that are defective in Arid3b show an abnormal distribution of the actin cytoskeleton and decreased motility in vitro. Moreover, movements of pre-AER cells and their contribution to the AER were defective in vivo in embryos with reduced Arid3b function. Our results show that Arid3b is involved in the regulation of cell motility and rearrangements that lead to AER maturation.
Digit morphogenesis: Is the tip different Casanova, Jesús C; Sanz-Ezquerro, Juan José
Development, growth & differentiation,
August 2007, Volume:
49, Issue:
6
Journal Article
Peer reviewed
Open access
Digit formation is the last step in the skeletal patterning of developing limbs. This process involves important aspects such as determination of chondrogenic versus interdigital areas; growth of ...digital rays with periodic segmentation to form joints and thus phalanges, and finally tip formation. Traditionally it was believed that the properties of digital rays were fixed at earlier stages, but recently a surprising plasticity of digit primordia at the time of condensation has been demonstrated. This implies the presence of local interactions that are able to modulate the particular programs that make a given digit, but we don't fully understand how they operate. An involvement of signaling from the interdigital spaces and from the apical ectodermal ridge has been proposed. Another interesting question is the formation of the last limb structure, digit tips, which may involve a specific molecular and cellular program. Indeed, the expression of several developmentally important genes is restricted to digit tips at late stages of limb development. Understanding the molecular and cellular interactions that lead to digit morphogenesis has important implications not only in the context of embryonic development (for example, how early cues received by cells are translated into anatomy or what are the mechanisms that control the cease of activity of signaling regions) but also in terms of limb diversification during evolution.
Tetrapods have two pairs of limbs, each typically with five digits, each of which has a defined number of phalanges derived from an archetypal formula 1. Much progress has been made in understanding ...vertebrate limb initiation and the patterning processes that determine digit number in developing limb buds, but little is known about how phalange number is controlled. We and others previously showed that an additional phalange can be induced in a chick toe if sonic hedgehog protein is applied in between developing digit primordia 2, 3. Here we show that formation of an additional phalange is associated with prolonged Fgf8 expression in the overlying apical ridge and that an Fgf Receptor inhibitor blocks its formation. The additional phalange is produced by elongation and segmentation of the penultimate phalange, suggesting that the digit tip forms when Fgf signaling ceases by a special mechanism, possibly involving Wnt signaling. Consistent with this, Fgfs inhibit tip formation whereas attenuation of Fgf signaling induces tip formation prematurely. We propose that duration of Fgf signaling from the ridge, responsible for elongation of digit primordia, coupled with a characteristic periodicity of joint formation, generates the appropriate number of phalanges in each digit. We also propose that the process that generates the digit tips is independent of that which generates more proximal phalanges. This has implications for understanding human limb congenital malformations and evolution of digit diversity.
p38 kinases are key elements of the cellular stress response in animals. They mediate the cell response to a multitude of stress stimuli, from osmotic shock to inflammation and oncogenes. However, it ...is unknown how such diversity of function in stress evolved in this kinase subfamily. Here, we show that the p38 kinase was already present in a common ancestor of animals and fungi. Later, in animals, it diversified into three JNK kinases and four p38 kinases. Moreover, we identified a fifth p38 paralog in fishes and amphibians. Our analysis shows that each p38 paralog has specific amino acid substitutions around the hinge point, a region between the N-terminal and C-terminal protein domains. We showed that this region can be used to distinguish between individual paralogs and predict their specificity. Finally, we showed that the response to hyperosmotic stress in
, a close unicellular relative of animals, follows a phosphorylation-dephosphorylation pattern typical of p38 kinases. At the same time,
's cells upregulate the expression of GPD1 protein resembling an osmotic stress response in yeasts. Overall, our results show that the ancestral p38 stress pathway originated in the root of opisthokonts, most likely as a cell's reaction to salinity change in the environment. In animals, the pathway became more complex and incorporated more stimuli and downstream targets due to the p38 sequence evolution in the docking and substrate binding sites around the hinge region. This study improves our understanding of p38 evolution and opens new perspectives for p38 research.
p38 Mitogen activated protein kinases (p38MAPK) are a group of evolutionary conserved protein kinases which are central for cell adaptation to environmental changes as well as for immune response, ...inflammation, tissue regeneration and tumour formation. The interest in this group of protein kinases has grown continually since their discovery. Recent studies using new genetic and pharmacological tools are providing helpful information on the function of these stress-activated protein kinases and show that they have an acute impact on the development of prevalent diseases related to inflammation, diabetes, neurodegeneration, and cancer. In this Special Issue we present novel advances and review the knowledge on the identification of p38MAPK substrates, functions, and regulation; mechanisms underlying the role of p38MAPK in malignant transformation and other pathologies; and therapeutic opportunities associated with regulation of p38MAPK activity.
Tbx3, a T-box gene family member related to the
Drosophila gene
optomotor blind (
omb) and encoding a transcription factor, is expressed in anterior and posterior stripes in developing chick limb ...buds.
Tbx3 haploinsufficiency has been linked with the human condition ulnar–mammary syndrome, in which predominantly posterior defects occur in the upper limb.
Omb is expressed in
Drosophila wing development in response to a signalling cascade involving Hedgehog and Dpp. Homologous vertebrate signals Sonic hedgehog (Shh) and bone morphogenetic protein 2 (Bmp2) are associated in chick limbs with signalling of the polarising region which controls anteroposterior pattern. Here we carried out tissue transplantations, grafted beads soaked in Shh, Bmps, and Noggin in chick limb buds, and analysed
Tbx3 expression. We also investigated
Tbx3 expression in limb buds of chicken and mouse mutants and retinoid-deficient quail in which anteroposterior patterning is abnormal. We show that
Tbx3 expression in anterior and posterior stripes is regulated differently. Posterior
Tbx3 expression is stable and depends on the signalling cascade centred on the polarising region involving Shh and Bmps, while anterior
Tbx3 expression is labile and depends on the balance between positive Bmp signals, produced anteriorly, and negative Shh signals, produced posteriorly. Our results are consistent with the idea that posterior
Tbx3 expression is involved in specifying digit pattern and thus provides an explanation for the posterior defects in human patients. Anterior
Tbx3 expression appears to be related to the width of limb bud, which determines digit number.
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