binding of α2ml1 to the low density lipoprotein receptor-related protein 1 (lrp1) reveals a new role for lrp1 in the human epidermis绑定α2ml1的低密度脂蛋白受体相关蛋白1(lrp1恰巧)揭示了一个新的角色lrp1恰巧在人类表皮.pdf

Binding of a2ML1 to the Low Density Lipoprotein Receptor-Related Protein 1 (LRP1) Reveals a New Role for LRP1 in the Human Epidermis 1 1 1 2 1 1 Marie-Florence Galliano , Eve Toulza , Nathalie Jonca , Steven L. Gonias , Guy Serre , Marina Guerrin * 1 UMR5165 UDEAR-CNRS/UPS, CHU PURPAN, Toulouse, France, 2 Department of Pathology, University of California San Diego, La Jolla, California, United States of America Abstract Background: The multifunctional receptor LRP1 has been shown to bind and internalize a large number of protein ligands with biological importance such as the pan-protease inhibitor a2-macroglobulin (a2M). We recently identified A2ML1, a new member of the a2M gene family, expressed in epidermis. a2ML1 might contribute to the regulation of desquamation through its inhibitory activity towards proteases of the chymotrypsin family, notably KLK7. The expression of LRP1 in epidermis as well as its ability to internalize a2ML1 was investigated. Methods and Principal Findings: In human epidermis, LRP1 is mainly expressed within the granular layer of the epidermis, which gathers the most differentiated keratinocytes, as shown by immunohistochemistry and immunofluorescence using two different antibodies. By using various experimental approaches, we show that the receptor binding domain of a2ML1 (RBDl) is specifically internalized into the macrophage-like cell line RAW and colocalizes with LRP1 upon internalization. Coimmunoprecipitation assays demonstrate that RBDl binds LRP1 at the cell surface. Addition of RAP, a universal inhibitor of ligand binding to LRP1, prevents RBDl binding at the cell surface as well as internalization into RAW cells. Silencing Lrp1 expression with specific