Tissue distribution and ontogeny of multidrug resistance protein 2, a phosphatidylcholine translocator, in rats.

Multidrug resistance protein 2 (Mdr2), encoded by ATP-binding cassette b4 (Abcb4), serves as a phospholipid flippase that is indispensable for phosphatidylcholine translocation. However, little was known about the regulation of Mdr2 in Sprague-Dawley rats, although they are commonly used for pre-clinical investigation as well as mechanistic study. Present study aims at determining the tissue distribution, gender difference and ontogeny of Mdr2 in rats on both gene and protein levels. Results showed that Mdr2 was highly expressed in liver, modestly enriched in brain and testis, and less distributed in gastrointestinal tracts. Gender-divergent and male-dominated distribution was observed in the Mdr2 mRNA expression of liver and generative organs. Developmental pattern of rat Mdr2 on protein level was not exactly consistent with that on mRNA level. In conclusion, there was a considerable distribution of rat Mdr2 in the brain, testis and intestine besides liver, and the ontogeny of Mdr2 performed in an age-dependent pattern with the post-transcriptional regulation.