TY - JOUR
T1 - Functional characterization of SORL1 variants in cell-based assays to investigate variant pathogenicity
AU - Fazeli, Elnaz
AU - Fazeli, Elham
AU - Fojtík, Petr
AU - Holstege, Henne
AU - Andersen, Olav M.
N1 - Publisher Copyright: © 2024 The Authors.
PY - 2024/4/8
Y1 - 2024/4/8
N2 - SORLA, the protein encoded by the SORL1 gene, has an important role in recycling cargo proteins to the cell surface. While SORLA loss-of-function variants occur almost exclusively in Alzheimer’s disease cases, the majority of SORL1 variants are missense variants that are individually rare and can have individual mechanisms how they impair SORLA function as well as have individual effect size on disease risk. However, since carriers mostly come from small pedigrees, it is challenging to determine variant penetrance, leaving clinical significance associated with most missense variants unclear. In this article, we present functional approaches to evaluate the pathogenicity of a SORL1 variant, p.D1105H. First, we generated our mutant receptor by inserting the D1105H variant into the full-length SORLA-WT receptor. Then using western blot analysis we quantified the effect of the mutation on maturation and shedding of the receptor for transfected cells, and finally applied a flow cytometry approach to quantify SORLA expression at the cell surface. The results showed decreased maturation, decreased shedding, and decreased cell surface expression of D1105H compared with wild-type SORLA. We propose how these approaches can be used to functionally assess the pathogenicity of SORL1 variants in the future. This article is part of a discussion meeting issue ‘Understanding the endo-lysosomal network in neurodegeneration’.
AB - SORLA, the protein encoded by the SORL1 gene, has an important role in recycling cargo proteins to the cell surface. While SORLA loss-of-function variants occur almost exclusively in Alzheimer’s disease cases, the majority of SORL1 variants are missense variants that are individually rare and can have individual mechanisms how they impair SORLA function as well as have individual effect size on disease risk. However, since carriers mostly come from small pedigrees, it is challenging to determine variant penetrance, leaving clinical significance associated with most missense variants unclear. In this article, we present functional approaches to evaluate the pathogenicity of a SORL1 variant, p.D1105H. First, we generated our mutant receptor by inserting the D1105H variant into the full-length SORLA-WT receptor. Then using western blot analysis we quantified the effect of the mutation on maturation and shedding of the receptor for transfected cells, and finally applied a flow cytometry approach to quantify SORLA expression at the cell surface. The results showed decreased maturation, decreased shedding, and decreased cell surface expression of D1105H compared with wild-type SORLA. We propose how these approaches can be used to functionally assess the pathogenicity of SORL1 variants in the future. This article is part of a discussion meeting issue ‘Understanding the endo-lysosomal network in neurodegeneration’.
KW - Alzheimer’s disease
KW - SORL1
KW - SORLA
KW - pathogenic variants
KW - receptor maturation
UR - http://www.scopus.com/inward/record.url?scp=85185614262&partnerID=8YFLogxK
U2 - 10.1098/rstb.2022.0377
DO - 10.1098/rstb.2022.0377
M3 - Article
C2 - 38368933
SN - 0962-8436
VL - 379
JO - Philosophical transactions of the Royal Society of London. Series B, Biological sciences
JF - Philosophical transactions of the Royal Society of London. Series B, Biological sciences
IS - 1899
M1 - 20220377
ER -