Human SNORA31 variations impair cortical neuron-intrinsic immunity to HSV-1 and underlie herpes simplex encephalitis.

Herpes simplex virus-1 (HSV-1) encephalitis (HSE) is typically sporadic. Inborn errors of TLR3- and DBR1-mediated central nervous system cell-intrinsic immunity can account for forebrain and brainstem HSE, respectively. We report five unrelated patients with forebrain HSE, each heterozygous for one of four rare variants of SNORA31, encoding a small nucleolar RNA of the H/ACA class that are predicted to direct the isomerization of uridine residues to pseudouridine in small nuclear RNA and ribosomal RNA. We show that CRISPR/Cas9-introduced bi- and monoallelic SNORA31 deletions render human pluripotent stem cell (hPSC)-derived cortical neurons susceptible to HSV-1. Accordingly, SNORA31-mutated patient hPSC-derived cortical neurons are susceptible to HSV-1, like those from TLR3- or STAT1-deficient patients. Exogenous interferon (IFN)-ß renders SNORA31- and TLR3- but not STAT1-mutated neurons resistant to HSV-1. Finally, transcriptome analysis of SNORA31-mutated neurons revealed normal responses to TLR3 and IFN-α/ß stimulation but abnormal responses to HSV-1. Human SNORA31 thus controls central nervous system neuron-intrinsic immunity to HSV-1 by a distinctive mechanism.

Sno-derived RNAs are prevalent molecular markers of cancer immunity.

Small nucleolar RNAs (snoRNAs) constitute a family of noncoding RNAs that are classically known as guide RNAs for processing and modification of ribosomal RNAs. Recently, it was discovered that snoRNAs can be further processed into sno-derived RNAs (sdRNAs), some of which are known to exhibit microRNA-like properties. SdRNAs have been implicated in human cancer; however, a systems-level sdRNA landscape in human cancers is lacking. Through integrative analysis of ~22 nt size-selected smRNA-seq datasets from 10,262 patient samples across 32 cancer types, we mapped a pan-cancer sdRNAome and interrogated its signatures in multiple clinically relevant features, particularly cancer immunity and clinical outcome. Aggregating sdRNA abundances by parental snoRNAs, these expression signatures alone are sufficient to distinguish patients with distinct cancer types. Interestingly, a large panel of sdRNAs are significantly correlated with features of the tumor-immune microenvironment, such as immunosuppressive markers, CD8+ T cell infiltration, cytolytic T cell activity, and tumor vasculature. A set of individual sdRNAs with tumor-immune signatures can also stratify patient survival. These findings implicate snoRNAs and their derivative sdRNAs as a class of prevalent noncoding molecular markers of human cancer immunity.

Artificial Analogues of Circulating Box C/D RNAs Induce Strong Innate Immune Response and MicroRNA Activation in Human Adenocarcinoma Cells.

Fragments of small nucleolar RNAs (snoRNAs) were found among various non-coding RNAs (ncRNAs) circulating in human blood. Currently, the function of such cell-free sno-derived-RNAs is not clearly defined. This work is aimed at identifying regulatory pathways controlled by extracellular snoRNAs. In order to determine the molecular targets and pathways affected by artificial snoRNAs, we performed Illumina array analysis of MCF-7 human adenocarcinoma cells transfected with box C/D RNAs. The genes related to the innate immune response and apoptotic cascades were found to be activated in transfected cells compared with control cells. Intriguingly, the transfection of MCF-7 cells with artificial box C/D snoRNAs also increased the transcription of several microRNAs, such as mir-574, mir-599 and mir-21. Our data demonstrated that extracellular snoRNAs introduced into human cells may function as gene expression modulators, with activation of microRNA genes being one of the regulatory mechanisms.

Characterization of the sequences encoding for Xenopus laevis box C/D snoRNP Nop56 protein.

Nop56p was initially identified in yeast as the third common component of the ribonucleoprotein particles (snoRNPs) assembled on box C/D small nucleolar RNAs (snoRNAs). Thereafter, the characterization of Nop56p homologs in Archaea and in several eukaryotes pointed to the highly conserved structure of this factor. Studies in yeast indicate that Nop56 is not required for the stability of box C/D snoRNAs. Through the isolation of a Xenopus laevis Nop56 cDNA clone, we have been able to characterize the X. laevis Nop56 protein (XNop56p). We showed that it is a common component of X. laevis box C/D snoRNPs and that it displays the same electrophoretic mobility of p62 protein that we previously characterized as a box C/D snoRNP component, not essential for snoRNA stability in X. laevis. Mapping the 5' end of X. laevis Nop56 transcript indicates that it starts with a pyrimidine tract and the analysis of genomic clones revealed a snoRNA encoded in one of NOP56 introns. Although these two characteristics could suggest that XNOP56 is a TOP gene, it is not translationally controlled in a growth-dependent manner.