Temporal expression of CD44 during embryonic chick limb development and modulation of its expression with retinoic acid

TGF-β gene is expressed at various developmental stages and its principle role may be an involvement in organogenesis. The present study was performed to investigate the temporal expression of these TGF-β isoforms in the developing limb of White Leghorn Chicken, Gallus gallus (L., 1758). TGF-β isoforms were expressed in the developing limb as revealed by whole-mount in situ hybridization, but each showed a different pattern of expression. TGF-β2 was the dominant isoform compared with the other two isoforms. TGF-β2 first appeared along the proximodistal axis of the limb at stage 24 and condensed at the tip at stage 26. At stages 2931, expression appeared in digits and then was extended to the interdigital spaces. A weak signal for TGF-β3 was first shown in the developing limb at stage 26, but there was no interdigital expression, unlike for TGF-β2. TGF-β4 was expressed in the developing limb at stage 26 and only in the interdigital spaces at stage 29. Reverse transcription polymerase chain reaction analysis also showed that the transcript levels of TGF-β isoforms, especially TGF-β2, drastically increased at stage 29. These results suggest that TGF-β isoforms, with their patterns of expression, are specific regulatory factors that participate in limb development and digit morphogenesis.

Download Full-text

Retinoic acid signaling is required during early chick limb development

Development ◽

10.1242/dev.122.5.1385 ◽

1996 ◽

Vol 122 (5) ◽

pp. 1385-1394 ◽

Cited By ~ 10

Author(s):

J.A. Helms ◽

C.H. Kim ◽

G. Eichele ◽

C. Thaller

Keyword(s):

Retinoic Acid ◽

Limb Development ◽

Acid Synthesis ◽

Apical Ectodermal Ridge ◽

Limb Bud ◽

Retinoid Receptor ◽

Limb Morphogenesis ◽

Wing Bud ◽

Zone Of Polarizing Activity

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.

Download Full-text

Attenuation of Hypertrophy in Human MSCs via Treatment with a Retinoic Acid Receptor Inverse Agonist

International Journal of Molecular Sciences ◽

10.3390/ijms21041444 ◽

2020 ◽

Vol 21 (4) ◽

pp. 1444 ◽

Cited By ~ 1

Author(s):

Moritz Riedl ◽

Christina Witzmann ◽

Matthias Koch ◽

Siegmund Lang ◽

Maximilian Kerschbaum ◽

...

Keyword(s):

Retinoic Acid ◽

Cell Fate ◽

Limb Development ◽

Retinoic Acid Receptor ◽

Cartilage Regeneration ◽

Inverse Agonist ◽

Cartilage Tissue ◽

Human Mscs ◽

Acid Receptor

In vitro chondrogenically differentiated mesenchymal stem cells (MSCs) have a tendency to undergo hypertrophy, mirroring the fate of transient “chondrocytes” in the growth plate. As hypertrophy would result in ossification, this fact limits their use in cartilage tissue engineering applications. During limb development, retinoic acid receptor (RAR) signaling exerts an important influence on cell fate of mesenchymal progenitors. While retinoids foster hypertrophy, suppression of RAR signaling seems to be required for chondrogenic differentiation. Therefore, we hypothesized that treatment of chondrogenically differentiating hMSCs with the RAR inverse agonist, BMS204,493 (further named BMS), would attenuate hypertrophy. We induced hypertrophy in chondrogenic precultured MSC pellets by the addition of bone morphogenetic protein 4. Direct activation of the RAR pathway by application of the physiological RAR agonist retinoic acid (RA) further enhanced the hypertrophic phenotype. However, BMS treatment reduced hypertrophic conversion in hMSCs, shown by decreased cell size, number of hypertrophic cells, and collagen type X deposition in histological analyses. BMS effects were dependent on the time point of application and strongest after early treatment during chondrogenic precultivation. The possibility of modifing hypertrophic cartilage via attenuation of RAR signaling by BMS could be helpful in producing stable engineered tissue for cartilage regeneration.

Download Full-text