TY - JOUR
T1 - Novel domain interaction regulates secretion of proprotein convertase subtilisin/kexin type 9 (PCSK9) protein
AU - Du, Fen
AU - Hui, Yvonne
AU - Zhang, Michelle
AU - Linton, MacRae F.
AU - Fazio, Sergio
AU - Fan, Daping
PY - 2011/12/16
Y1 - 2011/12/16
N2 - PCSK9 (proprotein convertase subtilisin/kexin type 9) has emerged as a novel therapeutic target for hypercholesterolemia due to its LDL receptor (LDLR)-reducing activity. Although its structure has been solved, the lack of a detailed understanding of the structure-function relation hinders efforts to develop small molecule inhibitors. In this study, we used mutagenesis and transfection approaches to investigate the roles of the prodomain (PD) and the C-terminal domain (CD) and its modules (CM1-3) in the secretion and function of PCSK9. Deletion of PD residues 31-40, 41-50, or 51-60 did not affect the self-cleavage, secretion, or LDLR-degrading activity of PCSK9, whereas deletion of residues 61-70 abolished all of these functions. Deletion of the entire CD protein did not impair PCSK9 self-cleavage or secretion but completely abolished LDLR-degrading activity. Deletion of any one or two of the CD modules did not affect self-cleavage but influenced secretion and LDLR-reducing activity. Furthermore, in cotransfection experiments, a secretion-defective PD deletion mutant (ΔPD) was efficiently secreted in the presence of CD deletion mutants. This was due to the transfer of PD from the cotransfected CD mutants to the ΔPD mutant. Finally, we found that a discrete CD protein fragment competed with full-length PCSK9 for binding to LDLR in vitro and attenuated PCSK9-mediated hypercholesterolemia in mice. These results show a previously unrecognized domain interaction as a critical determinant in PCSK9 secretion and function. This knowledge should fuel efforts to develop novel approaches to PCSK9 inhibition.
AB - PCSK9 (proprotein convertase subtilisin/kexin type 9) has emerged as a novel therapeutic target for hypercholesterolemia due to its LDL receptor (LDLR)-reducing activity. Although its structure has been solved, the lack of a detailed understanding of the structure-function relation hinders efforts to develop small molecule inhibitors. In this study, we used mutagenesis and transfection approaches to investigate the roles of the prodomain (PD) and the C-terminal domain (CD) and its modules (CM1-3) in the secretion and function of PCSK9. Deletion of PD residues 31-40, 41-50, or 51-60 did not affect the self-cleavage, secretion, or LDLR-degrading activity of PCSK9, whereas deletion of residues 61-70 abolished all of these functions. Deletion of the entire CD protein did not impair PCSK9 self-cleavage or secretion but completely abolished LDLR-degrading activity. Deletion of any one or two of the CD modules did not affect self-cleavage but influenced secretion and LDLR-reducing activity. Furthermore, in cotransfection experiments, a secretion-defective PD deletion mutant (ΔPD) was efficiently secreted in the presence of CD deletion mutants. This was due to the transfer of PD from the cotransfected CD mutants to the ΔPD mutant. Finally, we found that a discrete CD protein fragment competed with full-length PCSK9 for binding to LDLR in vitro and attenuated PCSK9-mediated hypercholesterolemia in mice. These results show a previously unrecognized domain interaction as a critical determinant in PCSK9 secretion and function. This knowledge should fuel efforts to develop novel approaches to PCSK9 inhibition.
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U2 - 10.1074/jbc.M111.273474
DO - 10.1074/jbc.M111.273474
M3 - Article
C2 - 22027821
AN - SCOPUS:83355169698
SN - 0021-9258
VL - 286
SP - 43054
EP - 43061
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 50
ER -