A catalytic hairpin assembly system with sliding replication for the detection of piRNAs

As novel noncoding small RNA molecules, piRNAs play crucial roles in cancer development. However, due to their short sequences, easy degradation, and low abundance, developing specific detection methods is challenging. Rapid and early detection is important for the early clinical detection of tumours. Here, a novel one-step, dual-signal amplification piRNA detection system based on sliding replication and catalytic hairpin assembly (CHA), termed CTA, was developed for rapid, ultrasensitive and specific detection of piRNA-823. By utilizing the unique characteristics of tandem repeat sequences to improve amplification efficiency and fluorescence signal intensity, CTA achieved efficient target recognition and signal amplification by embedding tandem repeat sequences in one of the hairpin probes and utilizing chain displacement reactions to produce strong and detectable signals. CTA detected piRNA-823 with a low detection limit of 70 fM. Moreover, the whole detection process could be completed within 45 min. In addition, CTA performed excellently in the detection of cell and cancer samples, and its detection results were consistent with those of RT-qPCR. More importantly, CTA was successfully applied to effectively differentiate between healthy individuals and patients with colorectal cancer. These findings suggest its promising application in the diagnosis of cancer.

PIWI-interacting RNAs in human diseases: databases and computational models

PIWI-interacting RNAs (piRNAs) are short 21-35 nucleotide molecules that comprise the largest class of non-coding RNAs and found in a large diversity of species including yeast, worms, flies, plants and mammals including humans. The most well-understood function of piRNAs is to monitor and protect the genome from transposons particularly in germline cells. Recent data suggest that piRNAs may have additional functions in somatic cells although they are expressed there in far lower abundance. Compared with microRNAs (miRNAs), piRNAs have more limited bioinformatics resources available. This review collates 39 piRNA specific and non-specific databases and bioinformatics resources, describes and compares their utility and attributes and provides an overview of their place in the field. In addition, we review 33 computational models based upon function: piRNA prediction, transposon element and mRNA-related piRNA prediction, cluster prediction, signature detection, target prediction and disease association. Based on the collection of databases and computational models, we identify trends and potential gaps in tool development. We further analyze the breadth and depth of piRNA data available in public sources, their contribution to specific human diseases, particularly in cancer and neurodegenerative conditions, and highlight a few specific piRNAs that appear to be associated with these diseases. This briefing presents the most recent and comprehensive mapping of piRNA bioinformatics resources including databases, models and tools for disease associations to date. Such a mapping should facilitate and stimulate further research on piRNAs.

Cardioprotective Roles of Endothelial Progenitor Cell-Derived Exosomes

With the globally increasing prevalence, cardiovascular diseases (CVDs) have become the leading cause of mortality. The transplantation of endothelial progenitor cells (EPCs) holds a great promise due to their potential for vasculogenesis, angiogenesis, and protective cytokine release, whose mechanisms are essential for CVD therapies. In reality, many investigations have attributed the therapeutic effects of EPC transplantation to the secretion of paracrine factors rather than the differentiation function. Of note, previous studies have suggested that EPCs could also release exosomes (diameter range of 30–150 nm), which carry various lipids and proteins and are abundant in microRNAs. The EPC-derived exosomes (EPC-EXs) were reported to act on the heart and blood vessels and were implicated in anti-inflammation, anti-oxidation, anti-apoptosis, the inhibition of endothelial-to-mesenchymal transition (EndMT), and cardiac fibrosis, as well as anti-vascular remodeling and angiogenesis, which were considered as protective effects against CVDs. In this review, we summarize the current knowledge on using EPC-EXs as therapeutic agents and provide a detailed description of their identified mechanisms of action to promote the prognosis of CVDs.