Expression of retinoic acid receptor and retinoid X receptor subtypes in rat liver cells: Implications for retinoid signalling in parenchymal, endothelial, Kupffer and stellate cells

In the present study, a systematic examination of the relative expres. sion pattern of the nuclear retinoid receptors (RAR and RXR) in various liver cells was performed. Our data demonstrate that RXRα is the dominant receptor in all liver cells, and that RARβ is also expressed at a high level in most cells. More specifically, RARβ and RARα were the most predominant of the RAR subtypes in parenchymal cells, while all three RAR subtypes were equally expressed in endothelial and Kupffer cells. The total level of expression of all the RXR subtypes were larger than the total level of expression of all the RAR subtypes in all liver cells. This is in agreement with the observation that RXR is a heterodimer partner not only for RAR, but also for other members in the steroid/thyroid receptor superfamily of liganddependent transcription factors.