Change of Heart: the Epitranscriptome of Small Non-coding RNAs in Heart Failure.

PURPOSE OF REVIEW: Small non-coding RNAs regulate gene expression and are highly implicated in heart failure. Recently, an additional level of post-transcriptional regulation has been identified, referred to as the epitranscriptome, which encompasses the body of post-transcriptional modifications that are placed on RNA molecules. In this review, we summarize the current knowledge on the small non-coding RNA epitranscriptome in heart failure. RECENT FINDINGS: With the rise of new methods to study RNA modifications, epitranscriptome research has begun to take flight. Over the past 3 years, the number of publications on the epitranscriptome in heart failure has significantly increased, and we expect many more highly relevant publications to come out over the next few years. Currently, at least six modifications on small non-coding RNAs have been investigated in heart failure-relevant studies, namely N6-adenosine, N5-cytosine and N7-guanosine methylation, 2'-O-ribose-methylation, adenosine-to-inosine editing, and isomiRs. Their potential role in heart failure is discussed.

MicroRNA-411 and Its 5'-IsomiR Have Distinct Targets and Functions and Are Differentially Regulated in the Vasculature under Ischemia.

MicroRNAs are posttranscriptional regulators of gene expression. As microRNAs can target many genes simultaneously, microRNAs can regulate complex multifactorial processes, including post-ischemic neovascularization, a major recovery pathway in cardiovascular disease. MicroRNAs select their target mRNAs via full complementary binding with their seed sequence, i.e., nucleotides 2-8 from the 5' end of a microRNA. The exact sequence of a mature microRNA, and thus of its 5' and 3' ends, is determined by two sequential cleavage steps of microRNA precursors, Drosha/DGCR8 and Dicer. When these cleavage steps result in nucleotide switches at the 5' end, forming a so-called 5'-isomiR, this results in a shift in the mature microRNA's seed sequence. The role of 5'-isomiRs in cardiovascular diseases is still unknown. Here, we characterize the expression and function of the 5'-isomiR of miR-411 (ISO-miR-411). ISO-miR-411 is abundantly expressed in human primary vascular cells. ISO-miR-411 has a different "targetome" from WT-miR-411, with only minor overlap. The ISO-miR-411/WT-miR-411 ratio is downregulated under acute ischemia, both in cells and a murine ischemia model, but is upregulated instead in chronically ischemic human blood vessels. ISO-miR-411 negatively influences vascular cell migration, whereas WT-miR-411 does not. Our data demonstrate that isomiR formation is a functional pathway that is actively regulated during ischemia.

A Preoperative Virtual Reality App for Patients Scheduled for Cardiac Catheterization: Pre-Post Questionnaire Study Examining Feasibility, Usability, and Acceptability.

BACKGROUND: Pre- and postoperative anxiety is a common phenomenon associated with negative postoperative outcomes. Symptoms of posttraumatic stress disorder, such as fear, nightmares, and sleep deprivation, are prevalent in approximately 30% to 50% of patients following discharge from intensive care units after cardiac surgery. Preliminary evidence suggests a promising role of virtual reality (VR) in preventing stress-related reactions using stress inoculation training. Such training enables cognitive preparation of individuals for stressful situations, thereby becoming more tolerant and resistant to stress, subsequently reducing the risk of potential negative psychological consequences. This study investigated a preoperative VR app-Pre-View-aimed at better informing and preparing patients for cardiac catheterization. OBJECTIVE: This study aims to assess the feasibility, usability, and acceptability of Pre-View in patients undergoing cardiac catheterization. METHODS: Eligible participants were adults scheduled for elective cardiac catheterization. Pre-View comprised an interactive virtual representation of the whole care process related to cardiac catheterization, from entering the hospital for admission to postprocedural stay and discharge. These processes were represented through 360° videos and interactive photos. Self-report questionnaires were completed at baseline (ie, before catheterization and after undergoing the VR experience) and after cardiac catheterization. Outcome measures included user experience and satisfaction, VR presence and immersive tendencies, and user friendliness. The perceived effectiveness was assessed exploratively. RESULTS: A total of 8 individuals, with a mean age of 67 (SD 7.5) years, participated in this study. Half of them underwent the VR experience at the hospital and the other half at home. Participants reported high levels of presence in the virtual environment (Presence Questionnaire score: mean 129.1, SD 13.4). The usability of Pre-View was well evaluated (System Usability Scale score: mean 89.1, SD 12.0), and patient satisfaction was high (Client Satisfaction Questionnaire score: mean 27.1, SD 3.2). Usability and satisfaction scores were higher for participants who underwent Pre-View at home versus those who underwent Pre-View at the hospital, although the latter group was significantly older; 72.8 versus 61.3, respectively. All participants reported Pre-View to be effective in terms of feeling better informed about the care process of cardiac catheterization. Most participants (7/8, 88%) reported Pre-View to be effective in terms of feeling better prepared for cardiac catheterization, acknowledging the potential of Pre-View in reducing negative psychological consequences after catheterization. CONCLUSIONS: The results provide initial support for the feasibility and acceptability of a preoperative VR app, creating a virtual environment that supports patient education and preparation for upcoming cardiac catheterization. More studies are needed to further investigate the effects of VR as a tool to better prepare patients for medical procedures, its effectiveness in reducing negative patient outcomes (eg, anxiety, stress, and postoperative recovery outcomes), and the generalizability of effects across different settings and patient populations.

C/D box snoRNA SNORD113-6 guides 2'-O-methylation and protects against site-specific fragmentation of tRNALeu(TAA) in vascular remodeling.

C/D box small nucleolar RNAs (snoRNAs) of the DLK1-DIO3 locus are associated with vascular remodeling and cardiovascular disease. None of these snoRNAs has any known targets yet except for one, AF357425/SNORD113-6. We previously showed that this snoRNA targets mRNAs of the integrin signaling pathway and affects arterial fibroblast function. Here, we aimed to identify whether AF357425/SNORD113-6 can also target small RNAs. We overexpressed or inhibited AF357425 in murine fibroblasts and performed small RNA sequencing. Expression of transfer (t)RNA fragments (tRFs) was predominantly regulated. Compared with overexpression, AF357425 knockdown led to an overall decrease in tRFs but with an enrichment in smaller tRFs (<30 nucleotides). We focused on tRNA leucine anti-codon TAA (tRNALeu(TAA)), which has a conserved predicted binding site for AF357425/SNORD113-6. Adjacent to this site, the tRNA is cleaved to form tRFLeu 47-64 in both primary murine and human fibroblasts and in intact human arteries. We show that AF357425/SNORD113-6 methylates tRNALeu(TAA) and thereby prevents the formation of tRFLeu 47-64. Exposing fibroblasts to oxidative or hypoxic stress increased AF357425/SNORD113-6 and tRNALeu(TAA) expression, but AF357425/SNORD113-6 knockdown did not increase tRFLeu 47-64 formation under stress even further. Thus, independent of cellular stress, AF357425/SNORD113-6 protects against site-specific fragmentation of tRNALeu(TAA) via 2'O-ribose-methylation.

Inhibition of microRNA-494-3p activates Wnt signaling and reduces proinflammatory macrophage polarization in atherosclerosis.

We have previously shown that treatment with third-generation antisense oligonucleotides against miR-494-3p (3GA-494) reduces atherosclerotic plaque progression and stabilizes lesions, both in early and established plaques, with reduced macrophage content in established plaques. Within the plaque, different subtypes of macrophages are present. Here, we aimed to investigate whether miR-494-3p directly influences macrophage polarization and activation. Human macrophages were polarized into either proinflammatory M1 or anti-inflammatory M2 macrophages and simultaneously treated with 3GA-494 or a control antisense (3GA-ctrl). We show that 3GA-494 treatment inhibited miR-494-3p in M1 macrophages and dampened M1 polarization, while in M2 macrophages miR-494-3p expression was induced and M2 polarization enhanced. The proinflammatory marker CCR2 was reduced in 3GA-494-treated atherosclerosis-prone mice. Pathway enrichment analysis predicted an overlap between miR-494-3p target genes in macrophage polarization and Wnt signaling. We demonstrate that miR-494-3p regulates expression levels of multiple Wnt signaling components, such as LRP6 and TBL1X. Wnt signaling appears activated upon treatment with 3GA-494, both in cultured M1 macrophages and in plaques of hypercholesterolemic mice. Taken together, 3GA-494 treatment dampened M1 polarization, at least in part via activated Wnt signaling, while M2 polarization was enhanced, which is both favorable in reducing atherosclerotic plaque formation and increasing plaque stability.