## Abstract To dissect the effect of hyperinsulinemia versus hyperglycemia on TNF‐related apoptosis inducing ligand (TRAIL) expression in the macrovascular district, we measured TRAIL mRNA and protein in four groups of animals: streptozotocin (SZT)‐induced diabetic rats, vehicle‐treated control ani
Retinoic acid down-regulates Tbx1 expression in vivo and in vitro
✍ Scribed by Catherine Roberts; Sarah M. Ivins; Chela T. James; Peter J. Scambler
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 339 KB
- Volume
- 232
- Category
- Article
- ISSN
- 1058-8388
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Both Tbx1 and retinoic acid (RA) are key players in embryonic pharyngeal development; loss of Tbx1 produces DiGeorge syndrome‐like phenotypes in mouse models as does disruption of retinoic acid homeostasis. We have demonstrated that perturbation of retinoic acid levels in the avian embryo produces altered Tbx1 expression. In vitamin A‐deficient quails, which lack endogenous retinoic acid, Tbx1 expression patterns were disrupted early in development and expression was subsequently lost in all tissues. “Gain‐of‐function” experiments where RA‐soaked beads were grafted into the pharyngeal region produced localized down‐regulation of Tbx1 expression. In these embryos, analysis of Shh and Foxa2, upstream control factors for Tbx1, suggested that the effect of RA was independent of this regulatory pathway. Real‐time polymerase chain reaction analysis of retinoic acid‐treated P19 cells showed a dose‐dependent repression of Tbx1 by retinoic acid. Repression of Tbx1 transcript levels was first evident after 8–12 hr in culture in the presence of retinoic acid, and to achieve the highest levels of repression, de novo protein synthesis was required. Developmental Dynamics 232:928–938, 2005. © 2005 Wiley‐Liss, Inc.
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