Novel Loss-of-Function PCSK9 Variant Is Associated with Low Plasma LDL Cholesterol in a French-Canadian Family and with Impaired Processing and Secretion in Cell Culture

Mayne, Janice; Dewpura, Thilina; Raymond, Angela; Bernier, Lise; Cousins, Marion; Ooi, Teik Chye; Davignon, Jean; Seidah, Nabil G.; Mbikay, Majambu; Chrétien, Michel

doi:10.1373/clinchem.2011.165191

Cited by 102 publications

(100 citation statements)

References 41 publications

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“…In this manner we specifically isolated the effects of each mutation on proteolysis and secretion and found that in certain cases the results were discordant. We specifically evaluated the effect of mutations at Gln-152 because the histidine mutation at this residue has been found in a hypocholesterolemic clinical cohort (36). Biochemical characterization of Q152H has previously shown that this mutant hinders PCSK9 processing by causing decreased intramolecular cleavage, leading to an intracellular accumulation of unprocessed proPCSK9 that interferes with wild-type proPCSK9 processing, producing a dominant-negative effect (37).…”

Section: Discussionmentioning

confidence: 99%

“…We thus focused on Gln-152 given that the Q152H mutation has been documented in a patient cohort as a dominant-negative, loss-of-function phenotype resulting in low serum LDL cholesterol and a reduced incidence of atherosclerotic heart disease (36,37). We began with a vertical mutagenesis strategy at Gln-152 to evaluate the requirements on secretion, as others have demonstrated the requirement of Gln-152 on intramolecular proteolysis previously (37).…”

Section: The Prodomain C Terminus Regulates Protein Secretion But Ismentioning

confidence: 99%

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The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Active Site and Cleavage Sequence Differentially Regulate Protein Secretion from Proteolysis

Chorba

Shokat

2014

Journal of Biological Chemistry

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Background: PCSK9 inhibition shows promise in the treatment of hypercholesterolemia and prevention of atherosclerotic heart disease. Results: PCSK9 proteolysis and secretion have different structural requirements near the protein active site. Conclusion: PCSK9 proteolysis and secretion occur in two separate steps. Significance: The PCSK9 active site can serve as an allosteric modulator of protein secretion, suggesting a new strategy for inhibition.

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Section: Discussionmentioning

confidence: 99%

Section: The Prodomain C Terminus Regulates Protein Secretion But Ismentioning

confidence: 99%

The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Active Site and Cleavage Sequence Differentially Regulate Protein Secretion from Proteolysis

Chorba

Shokat

2014

Journal of Biological Chemistry

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“…ER stress-induced FLAG-sXBP1 was visualized by staining for FLAG. To determine the cellular localization of PCSK9 in conditions of stress, HuH7 cells were transfected with WT V5-labeled PCSK9, as described previously (83), and stained for V5. Transfection of the HuH7 cells with this plasmid was performed at 60% confluence.…”

Section: Methodsmentioning

confidence: 99%

“…11754050, Life Technologies, Inc.). RT-PCR was completed using Fast SYBR Green (catalog no.4385610, Life Technologies, Inc.), as described previously (83).…”

Section: Methodsmentioning

confidence: 99%

Endoplasmic Reticulum Stress and Ca2+ Depletion Differentially Modulate the Sterol Regulatory Protein PCSK9 to Control Lipid Metabolism

Lebeau

Al‐Hashimi

Sood

et al. 2017

Journal of Biological Chemistry

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Edited by Roger J. ColbranAccumulating evidence implicates endoplasmic reticulum (ER) stress as a mediator of impaired lipid metabolism, thereby contributing to fatty liver disease and atherosclerosis. Previous studies demonstrated that ER stress can activate the sterol regulatory element-binding protein-2 (SREBP2), an ER-localized transcription factor that directly up-regulates sterol regulatory genes, including PCSK9. Given that PCSK9 contributes to atherosclerosis by targeting low density lipoprotein (LDL) receptor (LDLR) degradation, this study investigates a novel mechanism by which ER stress plays a role in lipid metabolism by examining its ability to modulate PCSK9 expression. Herein, we demonstrate the existence of two independent effects of ER stress on PCSK9 expression and secretion. In cultured HuH7 and HepG2 cells, agents or conditions that cause ER Ca 2؉ depletion, including thapsigargin, induced SREBP2-dependent up-regulation of PCSK9 expression. In contrast, a significant reduction in the secreted form of PCSK9 protein was observed in the media from both thapsigargin-and tunicamycin (TM)-treated HuH7 cells, mouse primary hepatocytes, and in the plasma of TMtreated C57BL/6 mice. Furthermore, TM significantly increased hepatic LDLR expression and reduced plasma LDL concentrations in mice. Based on these findings, we propose a model in which ER Ca 2؉ depletion promotes the activation of SREBP2 and subsequent transcription of PCSK9. However, conditions that cause ER stress regardless of their ability to dysregulate ER Ca 2؉ inhibit PCSK9 secretion, thereby reducing PCSK9-mediated LDLR degradation and promoting LDLR-dependent hepatic cholesterol uptake. Taken together, our studies provide evidence that the retention of PCSK9 in the ER may serve as a potential strategy for lowering LDL cholesterol levels.

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“…First identified in four members of a French-Canadian Quebec family (Mayne et al 2011), this mutation has been found in two other Quebec families. The families include 51 heterozygous and 3 homozygous carriers.…”

Section: From Proenzymes (Pcsk1-8) To Pcsk9 As An Escort Proteinmentioning

confidence: 92%

60 YEARS OF POMC: From the prohormone theory to pro-opiomelanocortin and to proprotein convertases (PCSK1 to PCSK9)

Chrétien

Mbikay

2016

Journal of Molecular Endocrinology

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Pro-opiomelanocortin (POMC), is a polyprotein expressed in the pituitary and the brain where it is proteolytically processed into peptide hormones and neuropeptides with distinct biological activities. It is the prototype of multipotent prohormones. The prohormone theory was first suggested in 1967 when Chrétien and Li discovered γ-lipotropin and observed that (i) it was part of β-lipotropin (β-LPH), a larger polypeptide characterized 2 years earlier and (ii) its C-terminus was β-melanocyte-stimulating hormone (β-MSH). This discovery led them to propose that the lipotropins might be related biosynthetically to the biologically active β-MSH in a precursor to end product relationship. The theory was widely confirmed in subsequent years. As we celebrate the 50th anniversary of the sequencing of β-LPH, we reflect over the lessons learned from the sequencing of those proteins; we explain their extension to the larger POMC precursor; we examine how the theory of precursor endoproteolysis they inspired became relevant for vast fields in biology; and how it led, after a long and arduous search, to the novel proteolytic enzymes called proprotein convertases. This family of nine enzymes plays multifaceted functions in growth, development, metabolism, endocrine, and brain functions. Their genetics has provided many insights into health and disease. Their therapeutic targeting is foreseeable in the near future. Thus, what started five decades ago as a theory based on POMC fragments, has opened up novel and productive avenues of biological and medical research, including, for our own current interest, a highly intriguing hypocholesterolemic Gln152His PCSK9 mutation in French-Canadian families.

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Novel Loss-of-Function PCSK9 Variant Is Associated with Low Plasma LDL Cholesterol in a French-Canadian Family and with Impaired Processing and Secretion in Cell Culture

Cited by 102 publications

References 41 publications

The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Active Site and Cleavage Sequence Differentially Regulate Protein Secretion from Proteolysis

The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Active Site and Cleavage Sequence Differentially Regulate Protein Secretion from Proteolysis

Endoplasmic Reticulum Stress and Ca2+ Depletion Differentially Modulate the Sterol Regulatory Protein PCSK9 to Control Lipid Metabolism

60 YEARS OF POMC: From the prohormone theory to pro-opiomelanocortin and to proprotein convertases (PCSK1 to PCSK9)

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