RNY (YRNA)-derived small RNAs regulate cell death and inflammation in monocytes/macrophages

Cell Death Dis. 2017 Jan 5;8(1):e2530. doi: 10.1038/cddis.2016.429.

Abstract

The recent discovery of new classes of small RNAs has opened unknown territories to explore new regulations of physiopathological events. We have recently demonstrated that RNY (or Y RNA)-derived small RNAs (referred to as s-RNYs) are an independent class of clinical biomarkers to detect coronary artery lesions and are associated with atherosclerosis burden. Here, we have studied the role of s-RNYs in human and mouse monocytes/macrophages and have shown that in lipid-laden monocytes/macrophages s-RNY expression is timely correlated to the activation of both NF-κB and caspase 3-dependent cell death pathways. Loss- or gain-of-function experiments demonstrated that s-RNYs activate caspase 3 and NF-κB signaling pathways ultimately promoting cell death and inflammatory responses. As, in atherosclerosis, Ro60-associated s-RNYs generated by apoptotic macrophages are released in the blood of patients, we have investigated the extracellular function of the s-RNY/Ro60 complex. Our data demonstrated that s-RNY/Ro60 complex induces caspase 3-dependent cell death and NF-κB-dependent inflammation, when added to the medium of cultured monocytes/macrophages. Finally, we have shown that s-RNY function is mediated by Toll-like receptor 7 (TLR7). Indeed using chloroquine, which disrupts signaling of endosome-localized TLRs 3, 7, 8 and 9 or the more specific TLR7/9 antagonist, the phosphorothioated oligonucleotide IRS954, we blocked the effect of either intracellular or extracellular s-RNYs. These results position s-RNYs as relevant novel functional molecules that impacts on macrophage physiopathology, indicating their potential role as mediators of inflammatory diseases, such as atherosclerosis.

MeSH terms

  • Animals
  • Apoptosis / genetics*
  • Atherosclerosis / genetics*
  • Atherosclerosis / metabolism
  • Atherosclerosis / pathology
  • Autoantigens / genetics*
  • Autoantigens / metabolism
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Humans
  • Inflammation / genetics*
  • Inflammation / metabolism
  • Inflammation / pathology
  • Macrophages / metabolism
  • Macrophages / pathology
  • Mice
  • Monocytes / metabolism
  • Monocytes / pathology
  • RNA, Small Cytoplasmic / genetics*
  • RNA, Small Cytoplasmic / metabolism
  • Ribonucleoproteins / genetics*
  • Ribonucleoproteins / metabolism
  • Toll-Like Receptor 7 / genetics

Substances

  • Autoantigens
  • RNA, Small Cytoplasmic
  • RO60 protein, human
  • Ribonucleoproteins
  • TLR7 protein, human
  • Toll-Like Receptor 7
  • Caspase 3