Front Cell Dev Biol. 2026 Jul 9;14:1828772. doi: 10.3389/fcell.2026.1828772. eCollection 2026.
ABSTRACT
Low-density lipoprotein (LDL) receptor-related protein 6 (LRP6) is crucial for the canonical wingless signaling pathway and the clearance of LDL from the bloodstream. Genetic variants in the LRP6 gene have been conclusively associated with cardiovascular diseases (CVDs) and metabolic syndrome. However, the structural, cellular, and functional implications of these variations have not been fully elucidated. In this study, we examined the subcellular localization, stability, and degradation of 10 LRP6 missense variants (K82N, R360H, Y418H, N433S, R473Q, S488Y, R611C, P1066T, P1206H, and I1264V) previously reported to be associated with various CVD conditions. We assessed the effect of these missense variants on LRP6 subcellular localization by overexpressing them in HeLa and human embryonic kidney (HEK293T) mammalian cell lines. Molecular dynamic (MD) simulation was performed on two variants to evaluate their stability. In addition, the stability of all the variants was evaluated experimentally by measuring their half-lives and comparing them to the wild-type (WT) protein, using cycloheximide chase assays and inhibitor treatments. Our findings suggest that approximately 45% of the wild-type LRP6 protein achieves its mature form within 24-48 h of overexpression, indicating its modest trafficking through the endoplasmic reticulum (ER), maturation, and transport to the plasma membrane. On the other hand, CVD-associated LRP6 variants Y418H, N433S, R473Q, and P1206H exhibited significantly lower maturation levels and, in some cases, were semi-quantitatively present in the immature form, suggesting retention within the ER and failure to pass the highly stringent ER quality control systems. The in silico stability assessment revealed that all 10 LRP6 missense variants are predicted to have a negative impact on protein stability. Interestingly, MD simulation elaborated that one fully ER-retained variant, P1066T, has altered structural interactions of the protein, affecting its folding. ER retention of some CVD-associated LRP6 variants could contribute to diseases via the reduction in LRP6 plasma membrane localization and consequently loss or reduction of LRP6 function, potentially leading to dysregulated signaling efficiency. This study contributes to improving our understanding of the cellular behavior of several LRP6 missense variants causing CVD conditions and has potential applications in diagnosis and the development of new therapies for their associated conditions.
PMID:42495722 | PMC:PMC13391902 | DOI:10.3389/fcell.2026.1828772