Elsevier

Biochemical Pharmacology

Volume 57, Issue 7, 1 April 1999, Pages 833-835
Biochemical Pharmacology

Original Articles
Sister of P-glycoprotein expression in different tissues

https://doi.org/10.1016/S0006-2952(98)00357-8Get rights and content

Abstract

Sister of P-glycoprotein (spgp) is a gene that is closely related to the P-glycoprotein family (Pgps). This class of proteins belongs to the superfamily of ATP-binding cassette transporters and is known for its involvement in pharmacological drug interactions. Therefore, this study investigated the distribution of spgp expression in different tissues known for their high levels of Pgps expression such as brain, liver, kidney, small- and large-gut mucosa. Analysis was done by using the reverse transcription-polymerase chain reaction. In addition to a high expression in the liver, we were able to demonstrate a significant spgp expression in brain grey cortex, small- and large-gut mucosa. Although Pgps are expressed in the kidney and brain capillary endothelial cells, no expression of spgp was detected in these tissues, which might indicate that spgp has no function in the blood–brain barrier and is not involved in the renal excretion of drugs.

Section snippets

RT-PCR

Total RNA was extracted using the RNeasy Mini Kit (Qiagen) according to the manufacturer’s protocol. It was prepared from freshly excised porcine brain grey cortex, liver, kidney cortex, small- and large-gut mucosa. RNA from confluent (10 days in culture) porcine brain capillary endothelial cells was also examined. Primary cultures of these endothelial cells were prepared as described earlier [9]. After DNase digestion, RNA was quantified using a GeneQuant photometer (Pharmacia). Its integrity

Results and discussion

Brain grey cortex, liver, kidney, small- and large-gut mucosa are known to express high levels of Pgps 3, 10, 11, 12, 13, 14, 15, 16. The distribution of spgp was therefore investigated in these tissues. With RT-PCR, spgp expression could be demonstrated in brain, liver, small and large gut, whereas no spgp could be detected in the kidney (Fig. 1). The identity of the gene product with spgp was confirmed by cDNA sequence analysis. To determine which types of Pgps are expressed by these porcine

Acknowledgements

This work was supported by the Swiss National Science Foundation (Grant 32-052918.97), a scholarship to M.T. from the Association of Chemical Industries Basel, research grants from the Sandoz Foundation, and the ASTRA Research Funds of the Dept. of Internal Medicine of the University Hospital, Basel. We also thank U. Behrens for excellent technical assistance and I. Arnet for many valuable discussions.

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