LDLR, VLDLR and APOBR in the pathophysiology of sporadic Alzheimer’s disease

Abstract

BackgroundAlzheimer’s disease (AD) and cholesterol homeostasis have long been linked, most notably by the identification of apolipoprotein E‐ε4 allele as the strongest risk factor. Yet the mechanism by which its pathogenic isoform ε4 impacts AD has remained elusive. Different GWA studies have identified other potential risk factors, many of which are also involved in the maintenance, homeostasis, mobilisation, and distribution of cholesterol. The aim of this study was to analyse three candidate genes involved in cholesterol metabolism, which showed preliminary significance and are strongly related to cholesterol processes and APOE neurobiology.MethodThe three candidates are the receptors LDLR, VLDLR and APOBR which were analysed using neocortical mRNA data from the Religious Orders study/ Memory and Aging Project ROSMAP cohort’s dataset. The receptor mRNA levels were contrasted against several AD pathological markers, such as Braak and CERAD stages. Other apolipoprotein mRNA levels were also analysed for significance. Age, Sex and ApoE4 genotype were also tested for effect.ResultPreliminary analyses showed significant correlation between mRNA levels of these receptors (most strongly VLDLR) and Braak stages (VLDLR p < 0.008), CERAD stages (VLDLR p < 0.001) as well as several proteins known to be involved in AD pathophysiology. VLDLR expression levels did not correlate with APOE mRNA levels (VLDLR; R2=0.176, p > 0.05) and were only significant in APOε4 negative subjects when split for APOε4 genotype (VLDLR Braak p < 0.003).ConclusionThe three receptors analysed so far appear to be involved at some level with AD pathophysiology. They will be further studied and investigated in both, symptomatic and pre‐symptomatic AD. The relationship between the receptors and APOE pathophysiology in sporadic AD remains unclear.