Breast cancer resistance protein (Bcrp1/Abcg2) is expressed in the harderian gland and mediates transport of conjugated protoporphyrin IX

Johan W. Jonker, Sandra Musters, Maria L. H. Vlaming, Torsten Plosch, Karin E. R. Gooijert, Michel J. Hillebrand, Hilde Rosing, Jos H. Beijnen, Henkjan J. Verkade, Alfred H. Schinkel*

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

30 Citaten (Scopus)


Proper regulation of intracellular levels of protoporphyrin IX (PPIX), the direct precursor of heme, is important for cell survival. A deficiency in ferrochelatase, which mediates the final step in heme biosynthesis, leads to erythropoietic protoporphyria (EPP), a photosensitivity syndrome caused by the accumulation of PPIX in the skin. We have previously shown that mice with a deficiency in the ABC transporter Bcrp1/Abcg2 display a novel type of protoporphyria. This protoporphyria is mild compared with ferrochelatase-dependent EPP, and in itself not sufficient to cause phototoxicity, but it might exacerbate the consequences of other porphyrias. In this study, we identified the mouse harderian gland as a novel expression site of Bcrp1. Because of its pronounced role in porphyrin secretion, the harderian gland presents a useful tool to study the mechanism of Bcrp1-related protoporphyria and transport of porphyrins. Bcrp1(-/-) harderian gland displayed a highly increased accumulation of PPIX glycoconjugates, and a similar shift was seen in Bcrp1(-/-) liver. Tear- and hepatobiliary excretion data suggest that Bcrp1 controls intracellular levels of PPIX by mediating high affinity transport of its glycoconjugates and possibly low-affinity transport of unconjugated PPIX. This mechanism may allow cells to prevent or reduce cytotoxicity of PPIX under excess conditions, without spillage under physiological conditions where PPIX is needed.

Originele taal-2English
Pagina's (van-tot)C2204-C2212
Aantal pagina's9
TijdschriftAmerican journal of physiology-Cell physiology
Nummer van het tijdschrift6
StatusPublished - jun-2007

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