The mesenchymal factor, FGF10, initiates and maintains the outgrowth of the chick limb bud through interaction with FGF8, an apical ectodermal factor

Development ◽  
1997 ◽  
Vol 124 (11) ◽  
pp. 2235-2244 ◽  
Author(s):  
H. Ohuchi ◽  
T. Nakagawa ◽  
A. Yamamoto ◽  
A. Araga ◽  
T. Ohata ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Limb Bud ◽  
Fibroblast Growth ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Bud Formation ◽  
Limb Mesenchyme ◽  
Vertebrate Limb ◽  
Fgf10 Expression ◽  
Zone Of Polarizing Activity

Vertebrate limb formation has been known to be initiated by a factor(s) secreted from the lateral plate mesoderm. In this report, we provide evidence that a member of the fibroblast growth factor (FGF) family, FGF10, emanates from the prospective limb mesoderm to serve as an endogenous initiator for limb bud formation. Fgf10 expression in the prospective limb mesenchyme precedes Fgf8 expression in the nascent apical ectoderm. Ectopic application of FGF10 to the chick embryonic flank can induce Fgf8 expression in the adjacent ectoderm, resulting in the formation of an additional complete limb. Expression of Fgf10 persists in the mesenchyme of the established limb bud and appears to interact with Fgf8 in the apical ectoderm and Sonic hedgehog in the zone of polarizing activity. These results suggest that FGF10 is a key mesenchymal factor involved in the initial budding as well as the continuous outgrowth of vertebrate limbs.

scholarly journals Opposing RA and FGF signals control proximodistal vertebrate limb development through regulation of Meis genes

Development ◽  
2000 ◽  
Vol 127 (18) ◽  
pp. 3961-3970 ◽  
Author(s):  
N. Mercader ◽  
E. Leonardo ◽  
M.E. Piedra ◽  
C. Martinez-A ◽  
M.A. Ros ◽  
...  
Keyword(s):  
Limb Development ◽  
Fibroblast Growth ◽  
Specific Function ◽  
Lateral Plate Mesoderm ◽  
Lateral Plate ◽  
Vertebrate Limb ◽  
Proximal Determinant ◽  
Vertebrate Limb Development ◽  
Limb Initiation

Vertebrate limbs develop in a temporal proximodistal sequence, with proximal regions specified and generated earlier than distal ones. Whereas considerable information is available on the mechanisms promoting limb growth, those involved in determining the proximodistal identity of limb parts remain largely unknown. We show here that retinoic acid (RA) is an upstream activator of the proximal determinant genes Meis1 and Meis2. RA promotes proximalization of limb cells and endogenous RA signaling is required to maintain the proximal Meis domain in the limb. RA synthesis and signaling range, which initially span the entire lateral plate mesoderm, become restricted to proximal limb domains by the apical ectodermal ridge (AER) activity following limb initiation. We identify fibroblast growth factor (FGF) as the main molecule responsible for this AER activity and propose a model integrating the role of FGF in limb cell proliferation, with a specific function in promoting distalization through inhibition of RA production and signaling.

Relationship between dose, distance and time in Sonic Hedgehog-mediated regulation of anteroposterior polarity in the chick limb

Development ◽  
1997 ◽  
Vol 124 (21) ◽  
pp. 4393-4404 ◽  
Author(s):  
Y. Yang ◽  
G. Drossopoulou ◽  
P.T. Chuang ◽  
D. Duprez ◽  
E. Marti ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Long Range ◽  
Sonic Hedgehog ◽  
Mirror Image ◽  
Limb Bud ◽  
Limb Mesenchyme ◽  
Significant Difference ◽  
Zone Of Polarizing Activity ◽  
Anteroposterior Polarity ◽  
Dose Dependent

Anteroposterior polarity in the vertebrate limb is thought to be regulated in response to signals derived from a specialized region of distal posterior mesenchyme, the zone of polarizing activity. Sonic Hedgehog (Shh) is expressed in the zone of polarizing activity and appears to mediate the action of the zone of polarizing activity. Here we have manipulated Shh signal in the limb to assess whether it acts as a long-range signal to directly pattern all the digits. Firstly, we demonstrate that alterations in digit development are dependent upon the dose of Shh applied. DiI-labeling experiments indicate that cells giving rise to the extra digits lie within a 300 microm radius of a Shh bead and that the most posterior digits come from cells that lie very close to the bead. A response to Shh involves a 12–16 hour period in which no irreversible changes in digit pattern occur. Increasing the time of exposure to Shh leads to specification of additional digits, firstly digit 2, then 3, then 4. Cell marking experiments demonstrate that cells giving rise to posterior digits are first specified as anterior digits and later adopt a more posterior character. To monitor the direct range of Shh signalling, we developed sensitive assays for localizing Shh by attaching alkaline phosphatase to Shh and introducing cells expressing these forms into the limb bud. These experiments demonstrate that long-range diffusion across the anteroposterior axis of the limb is possible. However, despite a dramatic difference in their diffusibility in the limb mesenchyme, the two forms of alkaline phosphatase-tagged Shh proteins share similar polarizing activity. Moreover, Shh-N (aminoterminal peptide of Shh)-coated beads and Shh-expressing cells also exhibit similar patterning activity despite a significant difference in the diffusibility of Shh from these two sources. Finally, we demonstrate that when Shh-N is attached to an integral membrane protein, cells transfected with this anchored signal also induce mirror-image pattern duplications in a dose-dependent fashion similar to the zone of polarizing activity itself. These data suggest that it is unlikely that Shh itself signals digit formation at a distance. Beads soaked in Shh-N do not induce Shh in anterior limb mesenchyme ruling out direct propagation of a Shh signal. However, Shh induces dose-dependent expression of Bmp genes in anterior mesenchyme at the start of the promotion phase. Taken together, these results argue that the dose-dependent effects of Shh in the regulation of anteroposterior pattern in the limb may be mediated by some other signal(s). BMPs are plausible candidates.

Autoregulation of Shh expression and Shh induction of cell death suggest a mechanism for modulating polarising activity during chick limb development

Development ◽  
2000 ◽  
Vol 127 (22) ◽  
pp. 4811-4823 ◽  
Author(s):  
J.J. Sanz-Ezquerro ◽  
C. Tickle
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Sonic Hedgehog ◽  
Limb Development ◽  
Retroviral Vector ◽  
Cellular Mechanism ◽  
Limb Bud ◽  
Drug Induced ◽  
Signalling Molecule ◽  
Vertebrate Limb

The polarising region expresses the signalling molecule sonic hedgehog (Shh), and is an embryonic signalling centre essential for outgrowth and patterning of the vertebrate limb. Previous work has suggested that there is a buffering mechanism that regulates polarising activity. Little is known about how the number of Shh-expressing cells is controlled but, paradoxically, the polarising region appears to overlap with the posterior necrotic zone, a region of programmed cell death. We have investigated how Shh expression and cell death respond when levels of polarising activity are altered, and show an autoregulatory effect of Shh on Shh expression and that Shh affects cell death in the posterior necrotic zone. When we increased Shh signalling, by grafting polarising region cells or applying Shh protein beads, this led to a reduction in the endogenous Shh domain and an increase in posterior cell death. In contrast, cells in other necrotic regions of the limb bud, including the interdigital areas, were rescued from death by Shh protein. Application of Shh protein to late limb buds also caused alterations in digit morphogenesis. When we reduced the number of Shh-expressing cells in the polarising region by surgery or drug-induced killing, this led to an expansion of the Shh domain and a decrease in the number of dead cells. Furthermore, direct prevention of cell death using a retroviral vector expressing Bcl2 led to an increase in Shh expression. Finally, we provide evidence that the fate of some of the Shh-expressing cells in the polarising region is to undergo apoptosis and contribute to the posterior necrotic zone during normal limb development. Taken together, these results show that there is a buffering system that regulates the number of Shh-expressing cells and thus polarising activity during limb development. They also suggest that cell death induced by Shh could be the cellular mechanism involved. Such an autoregulatory process based on cell death could represent a general way for regulating patterning signals in embryos.

dackel acts in the ectoderm of the zebrafish pectoral fin bud to maintain AER signaling

Development ◽  
2000 ◽  
Vol 127 (19) ◽  
pp. 4169-4178 ◽  
Author(s):  
H. Grandel ◽  
B.W. Draper ◽  
S. Schulte-Merker
Keyword(s):  
Transcription Factor ◽  
Growth Factor ◽  
Sonic Hedgehog ◽  
Limb Development ◽  
Induction Phase ◽  
Fibroblast Growth ◽  
Pectoral Fin ◽  
Vertebrate Limb ◽  
Fibroblast Growth Factor 10 ◽  
Vertebrate Limb Development

Classical embryological studies have implied the existence of an apical ectodermal maintenance factor (AEMF) that sustains signaling from the apical ectodermal ridge (AER) during vertebrate limb development. Recent evidence suggests that AEMF activity is composed of different signals involving both a sonic hedgehog (Shh) signal and a fibroblast growth factor 10 (Fgf10) signal from the mesenchyme. In this study we show that the product of the dackel (dak) gene is one of the components that acts in the epidermis of the zebrafish pectoral fin bud to maintain signaling from the apical fold, which is homologous to the AER of tetrapods. dak acts synergistically with Shh to induce fgf4 and fgf8 expression but independently of Shh in promoting apical fold morphogenesis. The failure of dak mutant fin buds to progress from the initial fin induction phase to the autonomous outgrowth phase causes loss of both AER and Shh activity, and subsequently results in a proximodistal truncation of the fin, similar to the result obtained by ridge ablation experiments in the chicken. Further analysis of the dak mutant phenotype indicates that the activity of the transcription factor engrailed 1 (En1) in the ventral non-ridge ectoderm also depends on a maintenance signal probably provided by the ridge. This result uncovers a new interaction between the AER and the dorsoventral organizer in the zebrafish pectoral fin bud.

Relationship between retinoic acid and sonic hedgehog, two polarizing signals in the chick wing bud

Development ◽  
1994 ◽  
Vol 120 (11) ◽  
pp. 3267-3274 ◽  
Author(s):  
J. Helms ◽  
C. Thaller ◽  
G. Eichele
Keyword(s):  
Retinoic Acid ◽  
Sonic Hedgehog ◽  
Positional Information ◽  
Limb Bud ◽  
Dependent Manner ◽  
All Trans Retinoic Acid ◽  
Wing Bud ◽  
Zone Of Polarizing Activity ◽  
Dose Dependent

Local application of all-trans-retinoic acid (RA) to the anterior margin of chick limb buds results in pattern duplications reminescent of those that develop after grafting cells from the zone of polarizing activity (ZPA). RA may act directly by conferring positional information to limb bud cells, or it may act indirectly by creating a polarizing region in the tissue distal to the RA source. Here we demonstrate that tissue distal to an RA-releasing bead acquires polarizing activity in a dose-dependent manner. Treatments with pharmacological (beads soaked in 330 micrograms/ml) and physiological (beads soaked in 10 micrograms/ml) doses of RA are equally capable of inducing digit pattern duplication. Additionally, both treatments induce sonic hedgehog (shh; also known as vertebrate hedgehog-1, vhh-1), a putative ZPA morphogen and Hoxd-11, a gene induced by the polarizing signal. However, tissue transplantation assays reveal that pharmacological, but not physiological, doses create a polarizing region. This differential response could be explained if physiological doses induced less shh than pharmacological doses. However, our in situ hybridization analyses demonstrate that both treatments result in similar amounts of mRNA encoding this candidate ZPA morphogen. We outline a model describing the apparently disparate effects of pharmacologic and physiological doses RA on limb bud tissue.

Embryonic retinoic acid synthesis is required for forelimb growth and anteroposterior patterning in the mouse

Development ◽  
2002 ◽  
Vol 129 (15) ◽  
pp. 3563-3574 ◽  
Author(s):  
Karen Niederreither ◽  
Julien Vermot ◽  
Brigitte Schuhbaur ◽  
Pierre Chambon ◽  
Pascal Dollé
Keyword(s):  
Retinoic Acid ◽  
Sonic Hedgehog ◽  
Acid Synthesis ◽  
Limb Bud ◽  
Anteroposterior Patterning ◽  
Limb Morphogenesis ◽  
Functional Zone ◽  
Mutant Mouse Embryos ◽  
Bud Growth ◽  
Zone Of Polarizing Activity

Numerous studies, often performed on avian embryos, have implicated retinoic acid (RA) in the control of limb bud growth and patterning. Here we have investigated whether the lack of endogenous RA synthesis affects limb morphogenesis in mutant mouse embryos deficient for the retinaldehyde dehydrogenase 2 (Raldh2/Aldh1a2). These mutants, which have no detectable embryonic RA except in the developing retina, die at E9.5-E10 without any evidence of limb bud formation, but maternal RA supplementation through oral gavage from E7.5 can extend their survival. Such survivors exhibit highly reduced forelimb rudiments, but apparently normal hindlimbs. By providing RA within maternal food, we found both a stage- and dose-dependency for rescue of forelimb growth and patterning. Following RA supplementation from E7.5 to 8.5, mutant forelimbs are markedly hypoplastic and lack anteroposterior (AP) patterning, with a single medial cartilage and 1-2 digit rudiments. RA provided until E9.5 significantly rescues forelimb growth, but cannot restore normal AP patterning. Increasing the RA dose rescues the hypodactyly, but leads to lack of asymmetry of the digit pattern, with abnormally long first digit or symmetrical polydactyly. Mutant forelimb buds are characterized by lack of expression or abnormal distal distribution of Sonic hedgehog (Shh) transcripts, sometimes with highest expression anteriorly. Downregulation or ectopic anterior expression of Fgf4 is also seen. As a result, genes such as Bmp2 or Hoxd genes are expressed symmetrically along the AP axis of the forelimb buds, and/or later, of the autopod. We suggest that RA signaling cooperates with a posteriorly restricted factor such as dHand, to generate a functional zone of polarizing activity (ZPA).

Role of dHAND in the anterior-posterior polarization of the limb bud: implications for the Sonic hedgehog pathway

Development ◽  
2000 ◽  
Vol 127 (10) ◽  
pp. 2133-2142 ◽  
Author(s):  
M. Fernandez-Teran ◽  
M.E. Piedra ◽  
I.S. Kathiriya ◽  
D. Srivastava ◽  
J.C. Rodriguez-Rey ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Limb Development ◽  
Mirror Image ◽  
Limb Bud ◽  
Bhlh Transcription Factor ◽  
Cardiovascular Development ◽  
Anterior Border ◽  
Lateral Plate ◽  
Shh Pathway ◽  
Anterior Posterior

dHAND is a basic helix-loop-helix (bHLH) transcription factor essential for cardiovascular development. Here we analyze its pattern of expression and functional role during chick limb development. dHAND expression was observed in the lateral plate mesoderm prior to emergence of the limb buds. Coincident with limb initiation, expression of dHAND became restricted to the posterior half of the limb bud. Experimental procedures that caused mirror-image duplications of the limb resulted in mirror-image duplications of the pattern of dHAND expression along the anterior-posterior axis. Retroviral overexpression of dHAND in the limb bud produced preaxial polydactyly, corresponding to mild polarizing activity at the anterior border. At the molecular level, misexpression of dHAND caused ectopic activation of members of the Sonic hedgehog (Shh) pathway, including Gli and Patched, in the anterior limb bud. A subset of infected embryos displayed ectopic anterior activation of Shh. Other factors implicated in anterior-posterior polarization of the bud such as the most 5′ Hoxd genes and Bmp2 were also ectopically activated at the anterior border. Our results indicate a role for dHAND in the establishment of anterior-posterior polarization of the limb bud.

scholarly journals Direct Reprogramming of Non-limb Fibroblasts to Cells with Properties of Limb Progenitors

2021 ◽  
Author(s):  
Yuji Atsuta ◽  
Changhee Lee ◽  
Alan R. Rodrigues ◽  
Charlotte Colle ◽  
Reiko R. Tomizawa ◽  
...  
Keyword(s):  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Cell Types ◽  
Limb Bud ◽  
Lateral Plate Mesoderm ◽  
Direct Reprogramming ◽  
Key Factors ◽  
Lateral Plate ◽  
Mesenchymal Progenitors ◽  
Similar Gene

SUMMARYThe early limb bud consists of mesenchymal progenitors (limb progenitors) derived from the lateral plate mesoderm (LPM) that produce most of the tissues of the mature limb bud. The LPM also gives rise to the mesodermal components of the trunk, flank and neck. However, the mesenchymal cells generated at these other axial levels cannot produce the variety of cell types found in the limb bud, nor can they be directed to form a patterned appendage-like structure, even when placed in the context of the signals responsible for organizing the limb bud. Here, by taking advantage of a direct reprogramming approach, we find a set of factors (Prdm16, Zbtb16, and Lin28) normally expressed in the early limb bud, that are capable of imparting limb progenitor-like properties to non-limb fibroblasts. Cells reprogrammed by these factors show similar gene expression profiles, and can differentiate into similar cell types, as endogenous limb progenitors. The further addition of Lin41 potentiates proliferation of the reprogrammed cells while suppressing differentiation. These results suggest that these same four key factors may play pivotal roles in the specification of endogenous limb progenitors.

Transient establishment of anteroposterior polarity in the zebrafish pectoral fin bud in the absence of sonic hedgehog activity

Development ◽  
1999 ◽  
Vol 126 (21) ◽  
pp. 4817-4826 ◽  
Author(s):  
C.J. Neumann ◽  
H. Grandel ◽  
W. Gaffield ◽  
S. Schulte-Merker ◽  
C. Nusslein-Volhard
Keyword(s):  
Retinoic Acid ◽  
Sonic Hedgehog ◽  
Limb Development ◽  
Normal Development ◽  
Limb Bud ◽  
Pectoral Fin ◽  
Anteroposterior Patterning ◽  
Vertebrate Limb ◽  
Anteroposterior Polarity

Sonic hedgehog (Shh) is expressed in the posterior vertebrate limb bud mesenchyme and directs anteroposterior patterning and growth during limb development. Here we report an analysis of the pectoral fin phenotype of zebrafish sonic you mutants, which disrupt the shh gene. We show that Shh is required for the establishment of some aspects of anteroposterior polarity, while other aspects of anteroposterior polarity are established independently of Shh, and only later come to depend on Shh for their maintenance. We also demonstrate that Shh is required for the activation of posterior HoxD genes by retinoic acid. Finally, we show that Shh is required for normal development of the apical ectodermal fold, for growth of the fin bud, and for formation of the fin endoskeleton.

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