Related Experiment Video
Updated: Jan 19, 2026
Engineering Oncogenic Heterozygous Gain-of-Function Mutations in Human Hematopoietic Stem and Progenitor Cells
Published on: March 10, 2023
The Arg499His gain-of-function mutation in the C-terminal domain of PCSK9
Rosa M Sánchez-Hernández1, Maria Donata Di Taranto2, Asier Benito-Vicente3
1Sección de Endocrinología y Nutrición, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
Insights
A novel PCSK9 gene variant, p.(Arg499His), causes familial hypercholesterolemia (FH) by promoting intracellular degradation of the LDL receptor. This leads to reduced LDL receptor availability and high cholesterol levels.
Area of Science:
- Genetics
- Molecular Biology
- Cardiovascular Disease
Background:
- Familial hypercholesterolemia (FH) is a genetic disorder causing high LDL cholesterol and early cardiovascular disease.
- Mutations in LDLR, APOB, or PCSK9 genes are known causes of FH.
- This study investigates a novel PCSK9 variant, p.(Arg499His), identified in FH patients.
Observation:
- The p.(Arg499His) PCSK9 variant was identified in two unrelated FH patients.
- Familial segregation and in vitro activity of the variant were studied.
- The variant affects PCSK9 expression, secretion, and LDL receptor interaction.
Findings:
- The p.(Arg499His) PCSK9 variant leads to reduced LDL receptor expression and uptake.
- Functional characterization revealed intracellular activity of the variant.
- This variant directly causes intracellular degradation of the LDL receptor, reducing its availability.
Implications:
- The p.(Arg499His) PCSK9 variant is a newly identified cause of FH.
- Understanding this variant's mechanism provides insight into cholesterol metabolism regulation.
- This discovery may inform future therapeutic strategies for FH.
Background And Aims:
Familial hypercholesterolemia (FH) is a monogenic disease characterized by high levels of low-density lipoprotein cholesterol and premature atherosclerotic cardiovascular disease. FH is caused by loss of function mutations in genes encoding LDL receptor (LDLR), and Apolipoprotein B (APOB) or gain of function (GOF) mutations in proprotein convertase subtilisin/kexin type 9 (PCSK9). In this study, we identified a novel variant in PCSK9, p.(Arg499His), located in the C-terminal domain, in two unrelated FH patients from Spain and Italy.
Methods:
We studied familial segregation and determined variant activity in vitro.
Results:
We determined PCSK9 expression, secretion and activity of the variant in transfected HEK293 cells; extracellular activity of the recombinant p.(Arg499His) PCSK9 variant in HEK 293 and HepG2 cells; PCSK9 affinity to the LDL receptor at neutral and acidic pH; the mechanism of action of the p.(Arg499His) PCSK9 variant by co-transfection with a soluble construct of the LDL receptor and by determining total PCSK9 intracellular accumulation when endosomal acidification is impaired and when an excess of soluble LDLr is present in the culture medium. Our results show high LDL-C concentrations and FH phenotype in p.(Arg499His) carriers. In vitro functional characterization shows that p.(Arg499His) PCSK9 variant causes a reduction in LDLr expression and LDL uptake. An intracellular activity for this variant is also shown when blocking the activity of secreted PCSK9 and by inhibiting endosomal acidification.
Conclusions:
We demonstrated that p.(Arg499His) PCSK9 variant causes a direct intracellular degradation of LDLr therefore causing FH by reducing LDLr availability.
Related Concept Videos
12:04Engineering Oncogenic Heterozygous Gain-of-Function Mutations in Human Hematopoietic Stem and Progenitor Cells
11:31Crystal Structure of the N-terminal Domain of Ryanodine Receptor from Plutella xylostella
06:18Measurement of Specific Mycobacterial Mistranslation Rates with Gain-of-function Reporter Systems
01:39Mutations
02:26Conservation of Protein Domains Over Different Proteins
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to...
08:14A High-Throughput Luciferase Assay to Evaluate Proteolysis of the Single-Turnover Protease PCSK9