Biology subjects

Semler, E. M.

Publications and source records attributed to Semler, E. M..

2 recordsLinked to original sources

bioRxiv2024

Post-transcriptional modifications on tRNA fragments confer functional changes to high-density lipoproteins in atherosclerosis

Epitranscriptomic modifications on RNA play critical roles in stability, processing, and function, partly by influencing interactions with RNA-binding proteins and receptors. The role of post-transcriptional RNA modifications on cell-free non-coding small RNA (sRNA) remains poorly understood in disease contexts. High-density lipoproteins (HDL), which transport sRNAs, can lose their beneficial properties in atherosclerosis cardiovascular disease (ASCVD). We hypothesize that changes to regulatory modifications on HDL-sRNAs contribute to this dysfunction. To assess changes in HDL-sRNA modification status, HDL-derived RNA from healthy subjects and those with atherosclerotic lesion development were analyzed using LC-MS/MS and AlkB-facilitated RNA (de)Methylation Sequencing. ASVD-HDL showed an enrichment in modified nucleosides including m1A tRNA-derived sRNAs (tDRs), particularly tDR-ArgACG-1. Functional studies revealed that ASCVD-HDL induced cell adhesion genes, including TMEM123, in primary macrophages. Recombinant HDL loaded with m1A-tDR-ArgACG-1 induced immune signaling, and similarly upregulated TMEM123. These findings suggest HDL-delivered-m1A-tDR-ArgACG-1 act on adhesion genes and immune pathways, promoting macrophage activation.

cell biology↗

bioRxiv2021

Physico-chemical principles of HDL-small RNA binding interactions.

Extracellular small RNAs (sRNA) are abundant in many biofluids, but little is known about their mechanisms of transport and stability in RNase-rich environments. We previously reported that high-density lipoproteins (HDL) of mice were enriched with multiple classes of sRNA derived from the endogenous transcriptome, but also exogenous organisms. Here, we show that human HDL transports tRNA-derived sRNAs (tDRs) from host and non-host species which were found to be altered in human atherosclerosis. We hypothesized that HDL binds to tDRs through apolipoprotein A-I (apoA-I) and these interactions are conferred by RNA-specific features. We tested this using microscale thermophoresis and electrophoretic mobility shift assays and found that HDL bind tDRs and other single-stranded sRNAs with strong affinity, but not doublestranded RNA or DNA. Natural and synthetic RNA modifications influenced tDR binding to HDL. Reconstituted HDL bound tDRs only in the presence of apoA-I and purified apoA-I alone was sufficient for binding sRNA. Conversely, phosphatidylcholine vesicles did not bind tDRs. In summary, HDL preferentially binds to single-stranded sRNAs likely through non-ionic interactions with apoA-I. These studies highlight binding properties that likely enable extracellular RNA communication and provide a foundation for future studies to manipulate HDL-sRNA for therapeutic approaches to prevent or treat disease.

molecular biology↗