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Kozan DW, Farber SA. Is It Ever Wise to Edit Wild-Type Alleles? Engineered CRISPR Alleles Versus Millions of Years of Human Evolution. Arterioscler Thromb Vasc Biol 2024; 44:328-333. [PMID: 38059350 PMCID: PMC10948015 DOI: 10.1161/atvbaha.123.318069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
The tremendous burden of lipid metabolism diseases, coupled with recent developments in human somatic gene editing, has motivated researchers to propose population-wide somatic gene editing of PCSK9 (proprotein convertase subtilisin/kexin type 9) within the livers of otherwise healthy humans. The best-characterized molecular function of PCSK9 is its ability to regulate plasma LDL (low-density lipoprotein) levels through promoting LDL receptor degradation. Individuals with loss-of-function PCSK9 variants have lower levels of plasma LDL and reduced cardiovascular disease. Gain-of-function variants of PCSK9 are strongly associated with familial hypercholesterolemia. A new therapeutic strategy delivers CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats; CRISPR-associated protein 9) specifically to liver cells to edit the wild-type alleles of PCSK9 with the goal of producing a loss-of-function allele. This direct somatic gene editing approach is being pursued despite the availability of US Food and Drug Administration-approved PCSK9 inhibitors that lower plasma LDL levels. Here, we discuss other characterized functions of PCSK9 including its role in infection and host immunity. We explore important factors that may have contributed to the evolutionary selection of PCSK9 in several vertebrates, including humans. Until such time that more fully understand the multiple biological roles of PCSK9, the ethics of permanently editing the gene locus in healthy, wild-type populations remains highly questionable.
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Affiliation(s)
- Darby W. Kozan
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States
| | - Steven A. Farber
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States
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Bao X, Liang Y, Chang H, Cai T, Feng B, Gordon K, Zhu Y, Shi H, He Y, Xie L. Targeting proprotein convertase subtilisin/kexin type 9 (PCSK9): from bench to bedside. Signal Transduct Target Ther 2024; 9:13. [PMID: 38185721 PMCID: PMC10772138 DOI: 10.1038/s41392-023-01690-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 09/27/2023] [Accepted: 10/27/2023] [Indexed: 01/09/2024] Open
Abstract
Proprotein convertase subtilisin/kexin type 9 (PCSK9) has evolved as a pivotal enzyme in lipid metabolism and a revolutionary therapeutic target for hypercholesterolemia and its related cardiovascular diseases (CVD). This comprehensive review delineates the intricate roles and wide-ranging implications of PCSK9, extending beyond CVD to emphasize its significance in diverse physiological and pathological states, including liver diseases, infectious diseases, autoimmune disorders, and notably, cancer. Our exploration offers insights into the interaction between PCSK9 and low-density lipoprotein receptors (LDLRs), elucidating its substantial impact on cholesterol homeostasis and cardiovascular health. It also details the evolution of PCSK9-targeted therapies, translating foundational bench discoveries into bedside applications for optimized patient care. The advent and clinical approval of innovative PCSK9 inhibitory therapies (PCSK9-iTs), including three monoclonal antibodies (Evolocumab, Alirocumab, and Tafolecimab) and one small interfering RNA (siRNA, Inclisiran), have marked a significant breakthrough in cardiovascular medicine. These therapies have demonstrated unparalleled efficacy in mitigating hypercholesterolemia, reducing cardiovascular risks, and have showcased profound value in clinical applications, offering novel therapeutic avenues and a promising future in personalized medicine for cardiovascular disorders. Furthermore, emerging research, inclusive of our findings, unveils PCSK9's potential role as a pivotal indicator for cancer prognosis and its prospective application as a transformative target for cancer treatment. This review also highlights PCSK9's aberrant expression in various cancer forms, its association with cancer prognosis, and its crucial roles in carcinogenesis and cancer immunity. In conclusion, this synthesized review integrates existing knowledge and novel insights on PCSK9, providing a holistic perspective on its transformative impact in reshaping therapeutic paradigms across various disorders. It emphasizes the clinical value and effect of PCSK9-iT, underscoring its potential in advancing the landscape of biomedical research and its capabilities in heralding new eras in personalized medicine.
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Affiliation(s)
- Xuhui Bao
- Institute of Therapeutic Cancer Vaccines, Fudan University Pudong Medical Center, Shanghai, China.
- Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai, China.
- Department of Oncology, Fudan University Pudong Medical Center, Shanghai, China.
- Center for Clinical Research, Fudan University Pudong Medical Center, Shanghai, China.
- Clinical Research Center for Cell-based Immunotherapy, Fudan University, Shanghai, China.
- Department of Pathology, Duke University Medical Center, Durham, NC, USA.
| | - Yongjun Liang
- Center for Medical Research and Innovation, Fudan University Pudong Medical Center, Shanghai, China
| | - Hanman Chang
- Institute for Food Safety and Health, Illinois Institute of Technology, Chicago, IL, USA
| | - Tianji Cai
- Department of Sociology, University of Macau, Taipa, Macau, China
| | - Baijie Feng
- Department of Oncology, Fudan University Pudong Medical Center, Shanghai, China
| | - Konstantin Gordon
- Medical Institute, Peoples' Friendship University of Russia, Moscow, Russia
- A. Tsyb Medical Radiological Research Center, Obninsk, Russia
| | - Yuekun Zhu
- Department of Colorectal Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Hailian Shi
- Shanghai Key Laboratory of Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Zhangjiang Hi-tech Park, Shanghai, China
| | - Yundong He
- Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai, China.
| | - Liyi Xie
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
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Hummelgaard S, Vilstrup JP, Gustafsen C, Glerup S, Weyer K. Targeting PCSK9 to tackle cardiovascular disease. Pharmacol Ther 2023; 249:108480. [PMID: 37331523 DOI: 10.1016/j.pharmthera.2023.108480] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 06/07/2023] [Accepted: 06/14/2023] [Indexed: 06/20/2023]
Abstract
Lowering blood cholesterol levels efficiently reduces the risk of developing atherosclerotic cardiovascular disease (ASCVD), including coronary artery disease (CAD), which is the main cause of death worldwide. CAD is caused by plaque formation, comprising cholesterol deposits in the coronary arteries. Proprotein convertase subtilisin kexin/type 9 (PCSK9) was discovered in the early 2000s and later identified as a key regulator of cholesterol metabolism. PCSK9 induces lysosomal degradation of the low-density lipoprotein (LDL) receptor in the liver, which is responsible for clearing LDL-cholesterol (LDL-C) from the circulation. Accordingly, gain-of-function PCSK9 mutations are causative of familial hypercholesterolemia, a severe condition with extremely high plasma cholesterol levels and increased ASCVD risk, whereas loss-of-function PCSK9 mutations are associated with very low LDL-C levels and protection against CAD. Since the discovery of PCSK9, extensive investigations in developing PCSK9 targeting therapies have been performed. The combined delineation of clear biology, genetic risk variants, and PCSK9 crystal structures have been major drivers in developing antagonistic molecules. Today, two antibody-based PCSK9 inhibitors have successfully progressed to clinical application and shown to be effective in reducing cholesterol levels and mitigating the risk of ASCVD events, including myocardial infarction, stroke, and death, without any major adverse effects. A third siRNA-based inhibitor has been FDA-approved but awaits cardiovascular outcome data. In this review, we outline the PCSK9 biology, focusing on the structure and nonsynonymous mutations reported in the PCSK9 gene and elaborate on PCSK9-lowering strategies under development. Finally, we discuss future perspectives with PCSK9 inhibition in other severe disorders beyond cardiovascular disease.
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Affiliation(s)
| | | | | | - Simon Glerup
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Draupnir Bio, INCUBA Skejby, Aarhus, Denmark
| | - Kathrin Weyer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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Abstract
This article reviews the discovery of PCSK9, its structure-function characteristics, and its presently known and proposed novel biological functions. The major critical function of PCSK9 deduced from human and mouse studies, as well as cellular and structural analyses, is its role in increasing the levels of circulating low-density lipoprotein (LDL)-cholesterol (LDLc), via its ability to enhance the sorting and escort of the cell surface LDL receptor (LDLR) to lysosomes. This implicates the binding of the catalytic domain of PCSK9 to the EGF-A domain of the LDLR. This also requires the presence of the C-terminal Cys/His-rich domain, its binding to the secreted cytosolic cyclase associated protein 1, and possibly another membrane-bound "protein X". Curiously, in PCSK9-deficient mice, an alternative to the downregulation of the surface levels of the LDLR by PCSK9 is taking place in the liver of female mice in a 17β-estradiol-dependent manner by still an unknown mechanism. Recent studies have extended our understanding of the biological functions of PCSK9, namely its implication in septic shock, vascular inflammation, viral infections (Dengue; SARS-CoV-2) or immune checkpoint modulation in cancer via the regulation of the cell surface levels of the T-cell receptor and MHC-I, which govern the antitumoral activity of CD8+ T cells. Because PCSK9 inhibition may be advantageous in these processes, the availability of injectable safe PCSK9 inhibitors that reduces by 50% to 60% LDLc above the effect of statins is highly valuable. Indeed, injectable PCSK9 monoclonal antibody or small interfering RNA could be added to current immunotherapies in cancer/metastasis.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), Montreal, QC, Canada
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), Montreal, QC, Canada
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Seidah NG. The PCSK9 discovery, an inactive protease with varied functions in hypercholesterolemia, viral infections, and cancer. J Lipid Res 2021; 62:100130. [PMID: 34606887 PMCID: PMC8551645 DOI: 10.1016/j.jlr.2021.100130] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/19/2021] [Accepted: 08/21/2021] [Indexed: 01/06/2023] Open
Abstract
In 2003, the sequences of mammalian proprotein convertase subtilisin/kexin type 9 (PCSK9) were reported. Radiolabeling pulse-chase analyses demonstrated that PCSK9 was synthesized as a precursor (proPCSK9) that undergoes autocatalytic cleavage in the endoplasmic reticulum into PCSK9, which is then secreted as an inactive enzyme in complex with its inhibitory prodomain. Its high mRNA expression in liver hepatocytes and its gene localization on chromosome 1p32, a third locus associated with familial hypercholesterolemia, other than LDLR or APOB, led us to identify three patient families expressing the PCSK9 variants S127R or F216L. Although Pcsk9 and Ldlr were downregulated in mice that were fed a cholesterol-rich diet, PCSK9 overexpression led to the degradation of the LDLR. This led to the demonstration that gain-of-function and loss-of-function variations in PCSK9 modulate its bioactivity, whereby PCSK9 binds the LDLR in a nonenzymatic fashion to induce its degradation in endosomes/lysosomes. PCSK9 was also shown to play major roles in targeting other receptors for degradation, thereby regulating various processes, including hypercholesterolemia and associated atherosclerosis, vascular inflammation, viral infections, and immune checkpoint regulation in cancer. Injectable PCSK9 monoclonal antibody or siRNA is currently used in clinics worldwide to treat hypercholesterolemia and could be combined with current therapies in cancer/metastasis. In this review, we present the critical information that led to the discovery of PCSK9 and its implication in LDL-C metabolism. We further analyze the underlying functional mechanism(s) in the regulation of LDL-C, as well as the evolving novel roles of PCSK9 in both health and disease states.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), 110 Pine Ave West, Montreal, QC, H2W 1R7, Canada.
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Ben Djoudi Ouadda A, Gauthier MS, Susan-Resiga D, Girard E, Essalmani R, Black M, Marcinkiewicz J, Forget D, Hamelin J, Evagelidis A, Ly K, Day R, Galarneau L, Corbin F, Coulombe B, Çaku A, Tagliabracci VS, Seidah NG. Ser-Phosphorylation of PCSK9 (Proprotein Convertase Subtilisin-Kexin 9) by Fam20C (Family With Sequence Similarity 20, Member C) Kinase Enhances Its Ability to Degrade the LDLR (Low-Density Lipoprotein Receptor). Arterioscler Thromb Vasc Biol 2019; 39:1996-2013. [PMID: 31553664 DOI: 10.1161/atvbaha.119.313247] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE PCSK9 (proprotein convertase subtilisin-kexin 9) enhances the degradation of the LDLR (low-density lipoprotein receptor) in endosomes/lysosomes. This study aimed to determine the sites of PCSK9 phosphorylation at Ser-residues and the consequences of such posttranslational modification on the secretion and activity of PCSK9 on the LDLR. Approach and Results: Fam20C (family with sequence similarity 20, member C) phosphorylates serines in secretory proteins containing the motif S-X-E/phospho-Ser, including the cholesterol-regulating PCSK9. In situ hybridization of Fam20C mRNA during development and in adult mice revealed a wide tissue distribution, including liver, but not small intestine. Here, we show that Fam20C phosphorylates PCSK9 at Serines 47, 666, 668, and 688. In hepatocytes, phosphorylation enhances PCSK9 secretion and maximizes its induced degradation of the LDLR via the extracellular and intracellular pathways. Replacing any of the 4 Ser by the phosphomimetic Glu or Asp enhanced PCSK9 activity only when the other sites are phosphorylated, whereas Ala substitutions reduced it, as evidenced by Western blotting, Elisa, and LDLR-immunolabeling. This newly uncovered PCSK9/LDLR regulation mechanism refines our understanding of the implication of global PCSK9 phosphorylation in the modulation of LDL-cholesterol and rationalizes the consequence of natural mutations, for example, S668R and E670G. Finally, the relationship of Ser-phosphorylation to the implication of PCSK9 in regulating LDL-cholesterol in the neurological Fragile X-syndrome disorder was investigated. CONCLUSIONS Ser-phosphorylation of PCSK9 maximizes both its secretion and activity on the LDLR. Mass spectrometric approaches to measure such modifications were developed and applied to quantify the levels of bioactive PCSK9 in human plasma under normal and pathological conditions.
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Affiliation(s)
- Ali Ben Djoudi Ouadda
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Marie-Soleil Gauthier
- Translational Proteomics Research Unit, Clinical Research Institute of Montreal (IRCM, affiliated to the Université de Montréal), QC, Canada (M.-S.G., D.F., B.C.)
| | - Delia Susan-Resiga
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Emmanuelle Girard
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Rachid Essalmani
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Miles Black
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas (M.B., V.S.T.)
| | - Jadwiga Marcinkiewicz
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Diane Forget
- Translational Proteomics Research Unit, Clinical Research Institute of Montreal (IRCM, affiliated to the Université de Montréal), QC, Canada (M.-S.G., D.F., B.C.)
| | - Josée Hamelin
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Alexandra Evagelidis
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Kevin Ly
- Institut de Pharmacologie, Université de Sherbrooke, QC, Canada (K.L., R.D.)
| | - Robert Day
- Institut de Pharmacologie, Université de Sherbrooke, QC, Canada (K.L., R.D.)
| | - Luc Galarneau
- Department of Biochemistry, Université de Sherbrooke, and Centre de Recherche du CHUS, QC, Canada (L.G., F.C., A.Ç.)
| | - Francois Corbin
- Department of Biochemistry, Université de Sherbrooke, and Centre de Recherche du CHUS, QC, Canada (L.G., F.C., A.Ç.)
| | - Benoit Coulombe
- Translational Proteomics Research Unit, Clinical Research Institute of Montreal (IRCM, affiliated to the Université de Montréal), QC, Canada (M.-S.G., D.F., B.C.)
| | - Artuela Çaku
- Department of Biochemistry, Université de Sherbrooke, and Centre de Recherche du CHUS, QC, Canada (L.G., F.C., A.Ç.)
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas (M.B., V.S.T.)
| | - Nabil G Seidah
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
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