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Benito-Vicente A, Uribe KB, Larrea-Sebal A, Palacios L, Cenarro A, Calle X, Galicia-Garcia U, Jebari-Benslaiman S, Sánchez-Hernández RM, Stef M, Lambert G, Civeira F, Martín C. Leu22_Leu23 Duplication at the Signal Peptide of PCSK9 Promotes Intracellular Degradation of LDLr and Autosomal Dominant Hypercholesterolemia. Arterioscler Thromb Vasc Biol 2022; 42:e203-e216. [PMID: 35510551 DOI: 10.1161/atvbaha.122.315499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND PCSK9 (Proprotein convertase subtilisin/kexin type 9) regulates LDL-C (low-density lipoprotein cholesterol) metabolism by targeting LDLr (LDL receptor) for lysosomal degradation. PCSK9 gain-of-function variants cause autosomal dominant hypercholesterolemia by reducing LDLr levels, the D374Y variant being the most severe, while loss-of-function variants are associated with low LDL-C levels. Gain-of-function and loss-of-function activities have also been attributed to variants occurring in the PCSK9 signal peptide. Among them, L11 is a very rare PCSK9 variant that seems to increase LDL-C values in a moderate way causing mild hypercholesterolemia. METHODS Using molecular biology and biophysics methodologies, activities of L8 and L11 variants, both located in the leucine repetition stretch of the signal peptide, have been extensively characterized in vitro. RESULTS L8 variant is not associated with increased LDLr activity, whereas L11 activity is increased by ≈20% compared with wt PCSK9. The results suggest that the L11 variant reduces LDLr levels intracellularly by a process resulting from impaired cleavage of the signal peptide. This would lead to less efficient LDLr transport to the cell membrane and promote LDLr intracellular degradation. CONCLUSIONS Deletion of a leucine in the signal peptide in L8 variant does not affect PCSK9 activity, whereas the leucine duplication in the L11 variant enhances LDLr intracellular degradation. These findings highlight the importance of deep in vitro characterization of PCSK9 genetic variants to determine pathogenicity and improve clinical diagnosis and therapy of inherited familial hypercholesterolemia disease.
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Affiliation(s)
- Asier Benito-Vicente
- Biofisika Institute (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain (A.B.-V., A.L.-S., U.G.-G., S.J.-B., C.M.).,Department of Biochemistry and Molecular Biology, UPV/EHU, University of the Basque Country, Bilbao, Spain (A.B.-V., S.J.-B., C.M.)
| | - Kepa B Uribe
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián, Spain (K.B.U.)
| | - Asier Larrea-Sebal
- Biofisika Institute (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain (A.B.-V., A.L.-S., U.G.-G., S.J.-B., C.M.).,Fundación Biofísica Bizkaia, Leioa, Spain (A.L.-S., U.G.-G.)
| | - Lourdes Palacios
- Progenika Biopharma, a Grifols Company, Derio, Spain (L.P., M.S.)
| | - Ana Cenarro
- Lipid Unit, Hospital Universitario Miguel Servet, IIS Aragon, CIBERCV, Universidad de Zaragoza, Spain (A.C., F.C.)
| | - Xabier Calle
- Institute of Biological Phychiatry, Mental Health Services, University Hospital, Copenhagen, Denmark (X.C.)
| | - Unai Galicia-Garcia
- Biofisika Institute (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain (A.B.-V., A.L.-S., U.G.-G., S.J.-B., C.M.).,Fundación Biofísica Bizkaia, Leioa, Spain (A.L.-S., U.G.-G.)
| | - Shifa Jebari-Benslaiman
- Biofisika Institute (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain (A.B.-V., A.L.-S., U.G.-G., S.J.-B., C.M.).,Department of Biochemistry and Molecular Biology, UPV/EHU, University of the Basque Country, Bilbao, Spain (A.B.-V., S.J.-B., C.M.)
| | - Rosa M Sánchez-Hernández
- Endocrinology Department, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria and Instituto Universitario de Investigación Biomédica y Sanitaria (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Spain (R.M.S.-H.)
| | - Marianne Stef
- Progenika Biopharma, a Grifols Company, Derio, Spain (L.P., M.S.)
| | - Gilles Lambert
- Inserm, Laboratoire UMR1188 DéTROI, Sainte Clotilde, France (G.L.).,Université de La Réunion, Faculté de Médecine, Saint Denis de La Réunion, France (G.L.)
| | - Fernando Civeira
- Lipid Unit, Hospital Universitario Miguel Servet, IIS Aragon, CIBERCV, Universidad de Zaragoza, Spain (A.C., F.C.)
| | - Cesar Martín
- Biofisika Institute (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain (A.B.-V., A.L.-S., U.G.-G., S.J.-B., C.M.).,Department of Biochemistry and Molecular Biology, UPV/EHU, University of the Basque Country, Bilbao, Spain (A.B.-V., S.J.-B., C.M.)
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Amaya Y, Nakai T. Localization and ER membrane insertion of parathyroid hormone-related protein analyzed without effects of reporter proteins. FEBS Lett 2019; 594:383-392. [PMID: 31471966 DOI: 10.1002/1873-3468.13592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 11/12/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) is transported to both the secretory pathway and the nucleus/nucleolus by its dual targeting signals, that is, an N-terminal signal peptide and nuclear targeting signal. Curiously, reporter proteins such as enhanced green fluorescent protein strongly affect the localization of the fusion protein. Here, we report a novel methionine tag for 35 S-labelling added to the C-terminus of its prepro-form, which has no methionine and cysteine residue other than the initiation methionine that enables analyses of the molecular mechanism of its dual localization without the effects of the reporter proteins. Mutational analyses including insertion of a glycosylation site for the tagged PTHrP revealed that the evolutionarily conserved regions in the signal peptide and the pro-region facilitate the redirection of ppPTHrP from the secretory pathway to the nuclear targeting pathway.
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Affiliation(s)
- Yoshihiro Amaya
- Division of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Toshiki Nakai
- Radioisotope Research Center, Yokohama City University School of Medicine, Japan
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