Symposium Pathobiology 1992:60:254-263
Christopher P.F. Redfern
Retinoic Acid Receptors
Medical Molecular Biology Group, Department of Dermatology, University of Newcastle Medical School, Newcastle upon Tyne, UK
Key Words
Retinoic acid receptors Transcriptional regulation Gene expression
Received: June I . 1991 Accepted: June 21,1991
As an experimental tool. vitamin-A-deficient animals have, in the past, been of considerable value in elucidat ing the mode of action of vitamin A. Feeding retinol to such animals results in rapid changes in the level and pat terns of mRNA synthesis, and this was interpreted as a direct effect of retinol on transcription [4], The subse quent discovery of cellular retinol-binding protein (CRBP) and cellular retinoic acid-binding protein (CRABP) in cytosolic extracts of many tissues [5] prompted speculation that retinol had a mechanism of action analogous to that of steroid hormones. Support for this idea came from experiments in which retinol, pre sented as a complex with CRBP, was shown to bind to isolated nuclei and chromatin, apparently specifically [6], Similar results were obtained using retinoic acid and CRABP [7], However, in in vitro binding experiments of this type, the amounts of labelled retinol or retinoic acid apparently transferred specifically to nuclei can be very high. Since retinoic acid dissociates rapidly from CRABP at room temperature [8] and can stick non-specifically to cellular components, the interpretation of such binding experiments may not be straightforward. To avoid such problems, we adopted conventional sucrose density gradient centrifugation to search for spe cific nuclear retinoic acid binding proteins or receptors. Using F9 teratocarcinoma cells incubated with tritiated retinoic acid for 2-3 h, we were able to show that retinoic acid bound specifically to a 4-4.5S nuclear protein, ex tractable from the nuclei in 0.6 M salt after digesting or
Dr. Christopher P.F. Redfern Medical Molecular Biology Group Department of Dermatology University of Newcastle Medical School Framlington Place. Newcastle upon TyneNE2 4HH (UK)
Christopher P.F. Redfern
Retinoic Acid Receptors
Medical Molecular Biology Group, Department of Dermatology, University of Newcastle Medical School, Newcastle upon Tyne, UK
Key Words
Retinoic acid receptors Transcriptional regulation Gene expression
Received: June I . 1991 Accepted: June 21,1991
As an experimental tool. vitamin-A-deficient animals have, in the past, been of considerable value in elucidat ing the mode of action of vitamin A. Feeding retinol to such animals results in rapid changes in the level and pat terns of mRNA synthesis, and this was interpreted as a direct effect of retinol on transcription [4], The subse quent discovery of cellular retinol-binding protein (CRBP) and cellular retinoic acid-binding protein (CRABP) in cytosolic extracts of many tissues [5] prompted speculation that retinol had a mechanism of action analogous to that of steroid hormones. Support for this idea came from experiments in which retinol, pre sented as a complex with CRBP, was shown to bind to isolated nuclei and chromatin, apparently specifically [6], Similar results were obtained using retinoic acid and CRABP [7], However, in in vitro binding experiments of this type, the amounts of labelled retinol or retinoic acid apparently transferred specifically to nuclei can be very high. Since retinoic acid dissociates rapidly from CRABP at room temperature [8] and can stick non-specifically to cellular components, the interpretation of such binding experiments may not be straightforward. To avoid such problems, we adopted conventional sucrose density gradient centrifugation to search for spe cific nuclear retinoic acid binding proteins or receptors. Using F9 teratocarcinoma cells incubated with tritiated retinoic acid for 2-3 h, we were able to show that retinoic acid bound specifically to a 4-4.5S nuclear protein, ex tractable from the nuclei in 0.6 M salt after digesting or
Dr. Christopher P.F. Redfern Medical Molecular Biology Group Department of Dermatology University of Newcastle Medical School Framlington Place. Newcastle upon TyneNE2 4HH (UK)
