Predicting sequence and structural features of effective piRNA target binding sites

Circulating PIWI-interacting RNAs in Acute Ischemic Stroke patients

Background

Stroke refers to an abrupt neurological deficit, caused by an acute focal injury of the central nervous system via infarction or hemorrhage due to impaired vascularity, and remains among the leading causes of disability and death worldwide. Stroke is often preceded by an episode of neuronal deficit termed transient ischemic attack (TIA), which presents an effective opportunity for mitigating the risk of an eminent acute ischemic stroke (AIS). Circulating non-coding RNAs (ncRNAs) have emerged as important biomarkers for stroke, but PIWI-interacting RNAs (piRNAs), a class of small regulatory ncRNAs, have not been previously explored as diagnostic or prognostic biomarkers for stroke.

Methods

We conducted comprehensive circulating piRNA profiling of AIS and TIA patients using RNA-seq on serum samples collected within 24 h of clinical diagnosis. The study cohort was divided into discovery and cross-validation datasets to identify replicated piRNAs using stringent analysis cut-offs. The expression levels of the panel of differentially regulated piRNAs between AIS and TIA patients were also compared with healthy controls.

Results

We identified a panel of 10 differentially regulated piRNAs between AIS and TIA patients; hsa-piR-28272, -piR-32972, -piR-28247, -piR-24553, -piR-24552, -piR-28275, -piR-28707 and -piR-32882 were upregulated, while hsa-piR-23058 and -piR-23136 were downregulated in AIS patients. Moreover, these 10 piRNAs were also differentially expressed in AIS patients compared to healthy controls. In addition, we investigated the potential gene targets of the dysregulated piRNAs and their plausible involvement in pathophysiological processes affected in stroke.

Conclusions

The imbalances in the circulating piRnome of AIS and TIA patients presented herein provide important insights into the roles of piRNAs following ischemic brain injury and potentially provide opportunities to mitigate stroke-induced mortality and morbidity.

Databases and computational methods for the identification of piRNA-related molecules: A survey

Piwi-interacting RNAs (piRNAs) are a class of small non-coding RNAs (ncRNAs) that plays important roles in many biological processes and major cancer diagnosis and treatment, thus becoming a hot research topic. This study aims to provide an in-depth review of computational piRNA-related research, including databases and computational models. Herein, we perform literature analysis and use comparative evaluation methods to summarize and analyze three aspects of computational piRNA-related research: (i) computational models for piRNA-related molecular identification tasks, (ii) computational models for piRNA-disease association prediction tasks, and (iii) computational resources and evaluation metrics for these tasks. This study shows that computational piRNA-related research has significantly progressed, exhibiting promising performance in recent years, whereas they also suffer from the emerging challenges of inconsistent naming systems and the lack of data. Different from other reviews on piRNA-related identification tasks that focus on the organization of datasets and computational methods, we pay more attention to the analysis of computational models, algorithms, and performances that aim to provide valuable references for computational piRNA-related identification tasks. This study will benefit the theoretical development and practical application of piRNAs by better understanding computational models and resources to investigate the biological functions and clinical implications of piRNA.

Interactions of piRNAs with the mRNA of Candidate Genes in Esophageal Squamous Cell Carcinoma

Recently, a database of human piRNAs (piwi-interacting RNAs) was created, which allows the study of the binding of many piRNAs to the mRNAs of genes involved in many diseases, including cancer. In the present work, we identified the piRNAs that can interact with candidate esophageal squamous cell carcinoma (ESCC) genes. The binding of 480 thousand piRNAs with the mRNAs of 66 candidate ESCC genes was studied. Bioinformatic studies found that piRNAs bind only to the mRNAs of nine candidate genes: AURKA, BMP7, GCOM1, ERCC1, MTHFR, SASH1, SIX4, SULT1A1, and TP53. It has been shown that piRNAs can bind to mRNA by overlapping nucleotide sequences in limited 3'UTR and 5'UTR regions called clusters of binding sites (BSs). The existence of clusters of piRNA BSs significantly reduces the proportion of the nucleotide sequences of these sites in the mRNA of target genes. Competition between piRNAs occurs for binding to the mRNA of target genes. Individual piRNAs and groups of piRNAs that have separate BSs and clusters of BSs in the mRNAs of two or more candidate genes have been identified in the mRNAs of these genes. This organization of piRNAs BSs indicates the interdependence of the expression of candidate genes through piRNAs. Significant differences in the ability of genes to interact with piRNAs prevent the side effects of piRNAs on genes with a lack of the ability to bind such piRNAs. Individual piRNAs and sets of piRNAs are proposed and recommended for the diagnosis and therapy of ESCC.