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The constitutive shedding of BP180 (collagen XVII) from human keratinocytes in culture was totally prevented by batimastat (5 microM), a wide spectrum matrix metalloprotease (MMP) inhibitor. However, keratinocytes did not express active MMP and generation of active Gelatinase A (MMP-2) and Gelatinase B (MMP-9) at the cell plasma membrane by increasing the ceramide content of keratinocytes did not influence BP180 processing to a 120 kDa species. A disintegrin and metalloprotease (ADAM) is probably involved in such a shedding event since release of 120 kDa polypeptide was inhibited by Decanoyl-Arg-Val-Lys-Arg CH2Cl (30 microM), a specific furin convertase inhibitor; culturing cells on to several matrix substrata i.e. type I collagen, type IV collagen, laminin-1 or laminin-5 had no effect on BP180 processing. Overall our data indicated that the metalloprotease-mediated shedding of BP180 from keratinocytes in culture is insensitive either to agents which activate MAP kinase pathway (ceramide) or to cell-matrix interactions.

We report the case of a 4-year-old girl, who had been suffering for 2 years from a recurrent, painful crisis affecting both hands, following sun exposure. There were no obvious cutaneous lesions, which initially caused us to consider a diagnosis of a psychiatric disorder. However, the diagnosis of erythropoietic protoporphyria was then established by the demonstration of elevated levels of free protoporphyrin in erythrocytes. The present case illustrates the effectiveness of beta-carotene associated with canthaxanthin in erythropoietic protoporphyria.