TY - JOUR
T1 - Relationships of APOE Genotypes with Small RNA and Protein Cargo of Brain Tissue Extracellular Vesicles from Patients with Late-Stage AD
AU - Huang, Yiyao
AU - Driedonks, Tom A.P.
AU - Cheng, Lesley
AU - Rajapaksha, Harinda
AU - Turchinovich, Andrey
AU - Routenberg, David A.
AU - Nagaraj, Rajini
AU - Redding-Ochoa, Javier
AU - Arab, Tanina
AU - Powell, Bonita H.
AU - Pletnikova, Olga
AU - Troncoso, Juan C.
AU - Zheng, Lei
AU - Hill, Andrew F.
AU - Mahairaki, Vasiliki
AU - Witwer, Kenneth W.
N1 - Funding Information:
V. Mahairaki and K.W. Witwer gratefully acknowledge support from the Richman Family Precision Medicine Center of Excellence in Alzheimer Disease including helpful comments and advice from founder and director Constantine Lyketsos. Thanks to: Kenneth Pienta, Johns Hopkins University School of Medicine, for access to the nanoFCM flow nanoAnalyzer platform; Mitchell Science Writing for manuscript editing and citation formatting; and the La Trobe University Comprehensive Proteomics Platform. The authors also thank members of the Witwer and Retrovirus Laboratories, Johns Hopkins University School of Medicine, and various members of the International Society for Extracellular Vesicles for valuable discussions and support.
Funding Information:
The Article Processing Charge was funded by the NIH.
Publisher Copyright:
© American Academy of Neurology.
PY - 2022/12/26
Y1 - 2022/12/26
N2 - Background and ObjectivesVariants of the apolipoprotein E (APOE) gene are the greatest known risk factors for sporadic Alzheimer disease (AD). Three major APOE isoform alleles, ϵ2, ϵ3, and ϵ4, encode and produce proteins that differ by only 1-2 amino acids but have different binding partner interactions. Whereas APOE ϵ2 is protective against AD relative to ϵ3, ϵ4 is associated with an increased risk for AD development. However, the role of APOE in gene regulation in AD pathogenesis has remained largely undetermined. Extracellular vesicles (EVs) are lipid bilayer-delimited particles released by cells to dispose of unwanted materials and mediate intercellular communication, and they are implicated in AD pathophysiology. Brain-derived EVs (bdEVs) could act locally in the tissue and reflect cellular changes. To reveal whether APOE genotype affects EV components in AD brains, bdEVs were separated from patients with AD with different APOE genotypes for parallel small RNA and protein profile.MethodsbdEVs from late-stage AD brains (BRAAK stages 5-6) from patients with APOE genotypes ϵ2/3 (n = 5), ϵ3/3 (n = 5), ϵ3/4 (n = 6), and ϵ4/4 (n = 6) were separated using our published protocol into a 10,000g pelleted extracellular fraction (10K) and a further purified EV fraction. Counting, sizing, and multiomic characterization by small RNA sequencing and proteomic analysis were performed for 10K, EVs, and source tissue.ResultsComparing APOE genotypes, no significant differences in bdEV total particle concentration or morphology were observed. Overall small RNA and protein profiles of 10K, EVs, and source tissue also did not differ substantially between different APOE genotypes. However, several differences in individual RNAs (including miRNAs and tRNAs) and proteins in 10K and EVs were observed when comparing the highest and lowest risk groups (ϵ4/4 and ϵ2/3). Bioinformatic analysis and previous publications indicate a potential regulatory role of these molecules in AD.DiscussionFor patients with late-stage AD in this study, only a few moderate differences were observed for small RNA and protein profiles between APOE genotypes. Among these, several newly identified 10K and EV-associated molecules may play roles in AD progression. Possibly, larger genotype-related differences exist and are more apparent in or before earlier disease stages.
AB - Background and ObjectivesVariants of the apolipoprotein E (APOE) gene are the greatest known risk factors for sporadic Alzheimer disease (AD). Three major APOE isoform alleles, ϵ2, ϵ3, and ϵ4, encode and produce proteins that differ by only 1-2 amino acids but have different binding partner interactions. Whereas APOE ϵ2 is protective against AD relative to ϵ3, ϵ4 is associated with an increased risk for AD development. However, the role of APOE in gene regulation in AD pathogenesis has remained largely undetermined. Extracellular vesicles (EVs) are lipid bilayer-delimited particles released by cells to dispose of unwanted materials and mediate intercellular communication, and they are implicated in AD pathophysiology. Brain-derived EVs (bdEVs) could act locally in the tissue and reflect cellular changes. To reveal whether APOE genotype affects EV components in AD brains, bdEVs were separated from patients with AD with different APOE genotypes for parallel small RNA and protein profile.MethodsbdEVs from late-stage AD brains (BRAAK stages 5-6) from patients with APOE genotypes ϵ2/3 (n = 5), ϵ3/3 (n = 5), ϵ3/4 (n = 6), and ϵ4/4 (n = 6) were separated using our published protocol into a 10,000g pelleted extracellular fraction (10K) and a further purified EV fraction. Counting, sizing, and multiomic characterization by small RNA sequencing and proteomic analysis were performed for 10K, EVs, and source tissue.ResultsComparing APOE genotypes, no significant differences in bdEV total particle concentration or morphology were observed. Overall small RNA and protein profiles of 10K, EVs, and source tissue also did not differ substantially between different APOE genotypes. However, several differences in individual RNAs (including miRNAs and tRNAs) and proteins in 10K and EVs were observed when comparing the highest and lowest risk groups (ϵ4/4 and ϵ2/3). Bioinformatic analysis and previous publications indicate a potential regulatory role of these molecules in AD.DiscussionFor patients with late-stage AD in this study, only a few moderate differences were observed for small RNA and protein profiles between APOE genotypes. Among these, several newly identified 10K and EV-associated molecules may play roles in AD progression. Possibly, larger genotype-related differences exist and are more apparent in or before earlier disease stages.
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U2 - 10.1212/NXG.0000000000200026
DO - 10.1212/NXG.0000000000200026
M3 - Article
C2 - 36405397
AN - SCOPUS:85143845550
SN - 2376-7839
VL - 8
JO - Neurology: Genetics
JF - Neurology: Genetics
IS - 6
M1 - e200026
ER -