Abstract
Exposure of aggregated murine P19 embryonal carcinoma cells to dimethylsulfoxide (DMSO) induces mesoderm and both embryonic cardiac and skeletal muscle differentiation, while retinoic acid (RA) is an inducer of neuroectodermal differentiation. P19 cells constitutively express the retinoic acid receptor α (RARα) and RARγ mRNAs while RARβ expression is induced by RA through a consensus RA-response element in the RARβ promoter. In the present study we show that the RARβ transcript is strongly expressed in both P19 cells and in a RA-nonresponsive derivative of P19 cells, called RAC65, during DMSO-induced mesoderm and muscle differentiation. Reverse transcriptase-polymerase chain reaction analysis indicated that RARβ2 is the predominant isoform expressed in DMSO-differentiated cells, providing the first evidence for RA-independent regulation of RARβ2 transcript levels. Immunoblot analysis showed a 3-fold increase in the RARβ protein expression over basal levels in differentiated cells, and immunohistochemistry indicated that all cells in the culture including muscle reacted positively for the RARβ protein. RARβ2 transcript expression was differentiation-dependent and occurred without transactivation of a transfected RAREβ2 reporter gene. Little transcription of the RARβ gene was detected in nuclear run-off assays of undifferentiated P19 cells and only a small increase in transcription was observed in nuclei from DMSO-treated cells. RA treatment of P19 cells stably transfected with the RA-responsive element from the RARβ gene showed that RARβ2 mRNA expression during DMSO differentiation was associated with increased sensitivity to RA. Together these data show that RARβ2 is expressed spontaneously in an apparently RA-independent manner in differentiating mesoderm and mesoderm derivatives, resulting in increased sensitivity to RA in these cells.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.