Retinoid-induced limb malformations.
The developing limb has been studied extensively and is a useful model to study morphogenesis. During embryogenesis, limb formation is initiated as a budding off from the embryonic lateral body wall. Limb pattern is specified by a series of epithelial-mesenchymal interactions, directing proximodistal, dorsoventral and anteroposterior axes. Vitamin A metabolites, especially retinoic acid, are known to play an important role in limb development, and the effects of retinoic acid may be mediated through the retinoid receptor signaling pathways. Accumulated evidence has shown that inadequate levels (excess or deficiency) of retinoic acid cause a wide range of limb malformations. Some species have the capacity to regenerate amputated limbs, and retinoids certainly affect this process, but there is debate regarding the extent that regeneration recapitulates development. In this review, phenotypic features, pathogenesis and the molecular basis of retinoid-induced limb malformations are discussed with a description of normal limb development and endogenous retinoid pathways.
Lee
Grace S
GS
Molecular Toxicology Interdepartmental Program, UCLA School of Public Health, Los Angeles, California 90095-1772, USA. mdc@ucla.edu
Kochhar
Devendra M
DM
Collins
Michael D
MD
D000818:Animals; D020219:Chondrogenesis / Q000502:physiology; D004333:Drug Administration Routes; D006801:Humans; D017880:Limb Deformities, Congenital / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000503:physiopathology; D010012:Osteogenesis / Q000502:physiology; D011859:Radiography; D012176:Retinoids / Q000008:administration & dosage / Q000009:adverse effects* / Q000172:deficiency
D012176:Retinoids