# Mechanisms by which Small Nucleolar RNAs Exacerbate Atherosclerosis

> **NIH NIH R01** · DUKE UNIVERSITY · 2022 · $586,990

## Abstract

Superoxide and other derivative reactive oxygen species (ROS) promote atherosclerosis (athero) as well as
vascular smooth muscle cell (SMC) and macrophage inflammatory signaling. Anti-atherogenic strategies
targeting O2--producing NADPH oxidases, however, increase susceptibility to infection. This project’s goal is to
discern novel mechanisms for constraining ROS-promoted atherogenesis while minimizing adverse effects on
immunity. One such mechanism may involve the ubiquitously expressed noncoding small nucleolar (sno)
RNAs from the ribosomal protein L13a (Rpl13a) locus: SNORD32A, SNORD33, SNORD34, and SNORD35A.
We found that these snoRNAs augment ROS levels and oxidative stress in vitro and in vivo. Our Preliminary
Studies with Rpl13a-snoRNA-/- (snoKO) mice and SMCs derived from them show: (1) snoKO SMCs have
lower levels of ROS, cell proliferation and migration than congenic WT SMCs. (2) Compared with WT SMCs,
snoKO SMCs express 5.7-fold more cytochrome C oxidase subunit 4 isoform 2 (COX4I2), which reduces
mitochondrial O2- production. (3) SnoKO carotid arteries develop less athero than WT carotids when
transplanted orthotopically into Apoe-/- mice. (4) Compared with Apoe-/- mice, snoKO/Apoe-/- mice develop
40% less brachiocephalic athero. (5) Compared with snoRNA+/+ brachiocephalic arteries or carotid grafts,
snoKO arteries demonstrate less SMC-to-foam-cell transdifferentiation, a process potentiated by ROS.
SnoRNAs bind to their target RNAs via an antisense domain, then recruit the enzyme fibrillarin, which effects
RNA 2’-O-methylation. SnoRNAs canonically modify ribosomal RNA; however, we discovered that at least one
of the Rpl13a snoRNAs can target mRNA for 2’-O-methylation—a process that alters mRNA abundance and
translation. Nonetheless, specific mRNAs that constitute targets for pro-oxidant effects of Rpl13a-snoRNAs
remain obscure. This project will therefore test the hypotheses that Rpl13a snoRNAs promote athero,
particularly by potentiating SMC-to-foam cell transdifferentiation, and that that Rpl13a-snoRNA-guided mRNA
2’-O-methylation affects protein expression of key ROS-regulating enzyme(s) in SMCs and Mφs, including
COX4I2. To do so, this project will compare athero in Rpl13a-snoRNA-/-/Apoe-/- versus Apoe-/- mice, and use
bone marrow transplantation to discern the roles of Rpl13a-snoRNAs in bone marrow-derived cells versus
arterial wall-derived cells. We will investigate how Rpl13a-snoRNAs affect foam cell formation in macrophages
and SMCs, and determine whether COX4I2 engenders lower ROS levels and inflammation in snoKO SMCs.
Finally, we will identify mRNA targets of Rpl13a-snoRNAs in SMCs and macrophages, by performing
transcriptome-wide mapping of 2’-O-methylation sites on mRNA from WT and Rpl13a-snoRNA-/- SMCs and
macrophages, by using the RibOxi-seq and crosslinking, ligation, and sequencing of hybrids (CLASH)
approach. By elucidating mechanisms by which snoRNAs regulate ROS in SMCs and macrophages, this
project should identify...

## Key facts

- **NIH application ID:** 10502380
- **Project number:** 1R01HL164542-01
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** NEIL J. FREEDMAN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $586,990
- **Award type:** 1
- **Project period:** 2022-08-01 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10502380

## Citation

> US National Institutes of Health, RePORTER application 10502380, Mechanisms by which Small Nucleolar RNAs Exacerbate Atherosclerosis (1R01HL164542-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10502380. Licensed CC0.

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