Aim:
The ATP-binding cassette transporter 1 (ABCA1) is a membrane protein well known for its role in cholesterol efflux and HDL formation. Recently, ABCA1 has been implicated as playing a key role in other processes, such as insulin secretion and inflammatory response. We sought to further investigate these potential roles through a quantitative proteomics approach. Specifically, we hypothesized that we could detect differential protein signatures in the plasma of Tangier patients that correspond to pathways involved in diabetes and inflammation.
Methods:
We used SOMAscan® technology (SomaLogic, Boulder, CO, USA) to analyze plasma collected from 5 Tangier disease patients (homozygotes or compound heterozygotes for functional
ABCA1
mutations) and 7 normolipidemic controls. We tested for differences in the levels of approximately 1,000 plasma proteins using a nonparametric test (KS). We then performed Ingenuity Canonical Pathway analysis to examine if proteins linked to diabetes and inflammation pathways were significantly more likely to be differentially abundant in the plasma. We corroborated the results using Gene Set Enrichment Analysis (GSEA).
Results:
We found an enrichment in differentially abundant proteins involved in type II diabetes mellitus signaling (p-value=0.0002) and inflammatory pathways, such as granulocyte adhesion and diapedesis (p-value=2.2*10
-12
). These results were also corroborated by GSEA, where gene sets corresponding to GO biological processes such as immune response (p-value=0.008) and inflammatory response (p-value=0.032) ranked at the top of the enrichment results.
Conclusions:
The results from this pilot study support the concept that ABCA1 is implicated in pathways affecting immune and inflammatory response and type II diabetes.
Novel mutations in the gene encoding ATP-binding cassette 1 in four Tangier disease kindreds
