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

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.

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1385-1394 ◽  
Author(s):  
J.A. Helms ◽  
C.H. Kim ◽  
G. Eichele ◽  
C. Thaller

In the chick limb bud, the zone of polarizing activity controls limb patterning along the anteroposterior and proximodistal axes. Since retinoic acid can induce ectopic polarizing activity, we examined whether this molecule plays a role in the establishment of the endogenous zone of polarizing activity. Grafts of wing bud mesenchyme treated with physiologic doses of retinoic acid had weak polarizing activity but inclusion of a retinoic acid-exposed apical ectodermal ridge or of prospective wing bud ectoderm evoked strong polarizing activity. Likewise, polarizing activity of prospective wing mesenchyme was markedly enhanced by co-grafting either a retinoic acid-exposed apical ectodermal ridge or ectoderm from the wing region. This equivalence of ectoderm-mesenchyme interactions required for the establishment of polarizing activity in retinoic acid-treated wing buds and in prospective wing tissue, suggests a role of retinoic acid in the establishment of the zone of polarizing activity. We found that prospective wing bud tissue is a high-point of retinoic acid synthesis. Furthermore, retinoid receptor-specific antagonists blocked limb morphogenesis and down-regulated a polarizing signal, sonic hedgehog. Limb agenesis was reversed when antagonist-exposed wing buds were treated with retinoic acid. Our results demonstrate a role of retinoic acid in the establishment of the endogenous zone of polarizing activity.


Author(s):  
Hiroki Yoshioka ◽  
Sai Shankar Ramakrishnan ◽  
Junbo Shim ◽  
Akiko Suzuki ◽  
Junichi Iwata

Cleft palate is the second most common congenital birth defect, and both environmental and genetic factors are involved in the etiology of the disease. However, it remains largely unknown how environmental factors affect palate development. Our previous studies show that several microRNAs (miRs) suppress the expression of genes involved in cleft palate. Here we show that miR-4680-3p plays a crucial role in cleft palate pathogenesis. We found that all-trans retinoic acid (atRA) specifically induces miR-4680-3p in cultured human embryonic palatal mesenchymal (HEPM) cells. Overexpression of miR-4680-3p inhibited cell proliferation in a dose-dependent manner through the suppression of expression of ERBB2 and JADE1, which are known cleft palate-related genes. Importantly, a miR-4680-3p-specific inhibitor normalized cell proliferation and altered expression of ERBB2 and JADE1 in cells treated with atRA. Taken together, our results suggest that upregulation of miR-4680-3p induced by atRA may cause cleft palate through suppression of ERBB2 and JADE1. Thus, miRs may be potential targets for the prevention and diagnosis of cleft palate.


1998 ◽  
Vol 275 (6) ◽  
pp. F938-F945 ◽  
Author(s):  
Evelyne Moreau ◽  
José Vilar ◽  
Martine Lelièvre-Pégorier ◽  
Claudie Merlet-Bénichou ◽  
Thierry Gilbert

Vitamin A and its derivatives have been shown to promote kidney development in vitro in a dose-dependent fashion. To address the molecular mechanisms by which all- trans-retinoic acid (RA) may regulate the nephron mass, rat kidneys were removed on embryonic day 14( E14) and grown in organ culture under standard or RA-stimulated conditions. By using RT-PCR, we studied the expression of the glial cell line-derived neurotrophic factor (GDNF), its cell surface receptor-α (GDNFR-α), and the receptor tyrosine kinase c-ret, known to play a major role in renal organogenesis. Expression of GDNF and GDNFR-α transcripts was high at the time of explantation and remained unaffected in culture with or without RA. In contrast, c-ret mRNA level, which was low in E14 metanephros and dropped rapidly in vitro, was increased by RA in a dose-dependent manner. The same is true at the protein level. Exogenous GDNF barely promotes additional nephron formation in vitro. Thus the present data establish c-ret as a key target of retinoids during kidney organogenesis.


Development ◽  
2002 ◽  
Vol 129 (15) ◽  
pp. 3563-3574 ◽  
Author(s):  
Karen Niederreither ◽  
Julien Vermot ◽  
Brigitte Schuhbaur ◽  
Pierre Chambon ◽  
Pascal Dollé

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).


2013 ◽  
Vol 20 (10) ◽  
pp. 1642-1646 ◽  
Author(s):  
Tristan I. Evans ◽  
R. Keith Reeves

ABSTRACTTissue-directed trafficking of dendritic cells (DCs) as natural adjuvants and/or direct vaccine carriers is highly attractive for the next generation of vaccines and immunotherapeutics. Since these types of studies would undoubtedly be first conducted using nonhuman primate models, we evaluated the ability of all-trans-retinoic acid (ATRA) to induce gut-homing α4β7 expression on rhesus macaque plasmacytoid and myeloid DCs (pDCs and mDCs, respectively). Induction of α4β7 occurred in both a time-dependent and a dose-dependent manner with up to 8-fold increases for mDCs and 2-fold increases for pDCs compared to medium controls. ATRA treatment was also specific in inducing α4β7 expression, but not expression of another mucosal trafficking receptor, CCR9. Unexpectedly, upregulation of α4β7 was associated with a concomitant downregulation of CD62L, a marker of lymph node homing, indicating an overall shift in the trafficking repertoire. These same phenomena occurred with ATRA treatment of human and chimpanzee DCs, suggesting a conserved mechanism among primates. Collectively, these data serve as a first evaluation forex vivomodification of primate DC homing patterns that could later be used in reinfusion studies for the purposes of immunotherapeutics or mucosa-directed vaccines.


1993 ◽  
Vol 295 (2) ◽  
pp. 343-346 ◽  
Author(s):  
C Carlberg ◽  
J H Saurat ◽  
G Siegenthaler

The pleiotropic activities of retinoids are mediated by two types of nuclear receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). All-trans-retinoic acid (RA) transcriptionally activates RARs, but not RXRs, whereas its natural stereoisomer, 9-cis-RA, is the ligand for RXRs. Here, we demonstrate that 9-cis-RA did not transcriptionally activate RARs, whereas in the presence of all-trans-RA the transactivation of RARs was inhibited in a dose-dependent manner by 9-cis-RA. RAR homodimer complexes were destabilized in vitro in the presence of 9-cis-RA. This suggests that 9-cis-RA may be a natural antagonist of all-trans-RA for binding to RAR complexes. The levels of 9-cis-RA may determine by which pathway the transcription of retinoid-responsive genes is modulated.


Development ◽  
1997 ◽  
Vol 124 (21) ◽  
pp. 4393-4404 ◽  
Author(s):  
Y. Yang ◽  
G. Drossopoulou ◽  
P.T. Chuang ◽  
D. Duprez ◽  
E. Marti ◽  
...  

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.


Development ◽  
1988 ◽  
Vol 103 (3) ◽  
pp. 473-483 ◽  
Author(s):  
C. Thaller ◽  
G. Eichele

Retinoids (vitamin A derivatives) have been shown to have striking effects on developing and regenerating vertebrate limbs. In the developing chick limb, retinoic acid is a candidate morphogen that may coordinate the pattern of cellular differentiation along the anteroposterior limb axis. We describe a series of investigations of the metabolic pathway of retinoids in the chick limb bud system. To study retinoid metabolism in the bud, all-trans-[3H]retinol, all-trans-[3H]retinal and all-trans-[3H]retinoic acid were released into the posterior region of the limb anlage, the area that contains the zone of polarizing activity, a tissue possibly involved in limb pattern formation. We found that the locally applied [3H]retinol is primarily converted to [3H]retinal, [3H]retinoic acid and a yet unidentified metabolite. When [3H]retinal is locally applied, it is either oxidized to [3H]retinoic acid or reduced to [3H]retinol. In contrast, local delivery of retinoic acid to the bud yields neither retinal nor retinol nor the unknown metabolite. This flow of metabolites agrees with the biochemical pathway of retinoids that has previously been elucidated in a number of other animal systems. To find out whether metabolism takes place directly in the treated limb bud, we have compared the amount of [3H]retinoid present in each of the four limb anlagen following local treatment of the right wing bud. The data suggest that retinoid metabolism takes place mostly in the treated limb bud. This local metabolism could provide a simple mechanism to generate in a controlled fashion the biologically active all-trans-retinoic acid from its abundant biosynthetic precursor retinol. In addition, local metabolism supports the hypothesis that retinoids are local chemical mediators involved in pattern formation.


2017 ◽  
Vol 43 (4) ◽  
pp. 1449-1459 ◽  
Author(s):  
Renata A. C. Silva ◽  
Andréa F. Gonçalves ◽  
Priscila P. dos Santos ◽  
Bruna Rafacho ◽  
Renan F. T. Claro ◽  
...  

Background/Aims: This study aimed to discern whether the cardiac alterations caused by retinoic acid (RA) in normal adult rats are physiologic or pathologic. Methods and Results: Wistar rats were assigned into four groups: control animals (C, n = 20) received a standard rat chow; animals fed a diet supplemented with 0.3 mg/kg/day all-trans-RA (AR1, n = 20); animals fed a diet supplemented with 5 mg/kg/day all-trans-RA (AR2, n = 20); and animals fed a diet supplemented with 10 mg/kg/day all-trans-RA (AR3, n = 20). After 2 months, the animals were submitted to echocardiogram, isolated heart study, histology, energy metabolism status, oxidative stress condition, and the signaling pathway involved in the cardiac remodeling induced by RA. RA increased myocyte cross-sectional area in a dose-dependent manner. The treatment did not change the morphological and functional variables, assessed by echocardiogram and isolated heart study. In contrast, RA changed catalases, superoxide dismutase, and glutathione peroxidases and was associated with increased values of lipid hydroperoxide, suggesting oxidative stress. RA also reduced citrate synthase, enzymatic mitochondrial complex II, ATP synthase, and enzymes of fatty acid metabolism and was associated with increased enzymes involved in glucose use. In addition, RA increased JNK 1/2 expression, without changes in TGF-β, PI3K, AKT, NFκB, S6K, and ERK. Conclusion: In normal rats, RA induces cardiac hypertrophy in a dose-dependent manner. The non-participation of the PI3K/Akt pathway, associated with the participation of the JNK pathway, oxidative stress, and changes in energy metabolism, suggests that cardiac remodeling induced by RA supplementation is deleterious.


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