PIWI-interacting RNAs and PIWI proteins in diabetes and cardiovascular disease: Molecular pathogenesis and role as biomarkers

Recent advances of PIWI-interacting RNA in cardiovascular diseases

BACKGROUND

The relationship between noncoding RNAs (ncRNAs) and human diseases has been a hot topic of research, but the study of ncRNAs in cardiovascular diseases (CVDs) is still in its infancy. PIWI-interacting RNA (piRNA), a small ncRNA that binds to the PIWI protein to maintain genome stability by silencing transposons, was widely studied in germ lines and stem cells. In recent years, piRNA has been shown to be involved in key events of multiple CVDs through various epigenetic modifications, revealing the potential value of piRNA as a new biomarker or therapeutic target.

CONCLUSION

This review explores origin, degradation, function, mechanism and important role of piRNA in CVDs, and the promising therapeutic targets of piRNA were summarized. This review provide a new strategy for the treatment of CVDs and lay a theoretical foundation for future research.

KEY POINTS

piRNA can be used as a potential therapeutic target and biomaker in CVDs. piRNA influences apoptosis, inflammation and angiogenesis by regulating epigenetic modificaions. Critical knowledge gaps remain in the unifying piRNA nomenclature and PIWI-independent function.

Potential molecular mechanisms and clinical implications of piRNAs in preeclampsia: a review

Preeclampsia is a multisystem progressive condition and is one of the most serious complications of pregnancy. Owing to its unclear pathogenesis, there are no precise and effective therapeutic targets for preeclampsia, and the only available treatment strategy is to terminate the pregnancy and eliminate the clinical symptoms. In recent years, non-coding RNAs have become a hotspot in preeclampsia research and have shown promise as effective biomarkers for the early diagnosis of preeclampsia over conventional biochemical markers. PIWI-interacting RNAs, novel small non-coding RNA that interact with PIWI proteins, are involved in the pathogenesis of various diseases at the transcriptional or post-transcriptional level. However, the mechanisms underlying the role of PIWI-interacting RNAs in the pathogenesis of preeclampsia remain unclear. In this review, we discuss the findings of existing studies on PIWI-interacting RNA biogenesis, functions, and their possible roles in preeclampsia, providing novel insights into the potential application of PIWI-interacting RNAs in the early diagnosis and clinical treatment of preeclampsia.

Identifying piRNAs that regulate BaP-induced lung injuries: A bottom-up approach from toxicity pathway investigation to animal validation

PIWI-interacting RNAs (piRNAs) is an emerging class of small non-coding RNAs that has been recently reported to have functions in infertility, tumorigenesis, and multiple diseases in humans. Previously, 5 toxicity pathways were proposed from hundreds of toxicological studies that underlie BaP-induced lung injuries, and a "Bottom-up" approach was established to identify small non-coding RNAs that drive BaP-induced pulmonary effects by investigating the activation of these pathways in vitro, and the expression of the candidate microRNAs were validated in tissues of patients with lung diseases from publications. Here in this study, we employed the "Bottom-up" approach to identifying the roles of piRNAs and further validated the mechanisms in vivo using mouse acute lung injury model. Specifically, by non-coding RNA profiling in in vitro BaP exposure, a total of 3 suppressed piRNAs that regulate 5 toxicity pathways were proposed, including piR-004153 targeting CYP1A1, FGFR1, ITGA5, IL6R, NGRF, and SDHA, piR-020326 targeting CDK6, and piR-020388 targeting RASD1. Animal experiments demonstrated that tail vein injection of respective formulated agomir-piRNAs prior to BaP exposure could all alleviate acute lung injury that was shown by histopathological and biochemical evidences. Immunohistochemical evaluation focusing on NF-kB and Bcl-2 levels showed that exogenous piRNAs protect against BaP-induced inflammation and apoptosis, which further support that the inhibition of the 3 piRNAs had an important impact on BaP-induced lung injuries. This mechanism-driven, endpoint-supported result once again confirmed the plausibility and efficiency of the approach integrating in silico, in vitro, and in vivo evidences for the purpose of identifying key molecules.

Expression and diagnostic value of PIWI-interacting RNA by serum in acute myocardial infarction

OBJECTIVE

To detect the expression level of PIWI-interacting RNA in the serum of patients with acute myocardial infarction, and to explore the role of PIWI-interacting RNA in acute myocardial infarction.

METHODS

RNA was extracted from the serum of acute myocardial infarction patients and healthy subjects, and high-throughput sequencing of PIWI-interacting RNAs was performed to screen differentially expressed PIWI-interacting RNAs. Quantitative polymerase chain reaction was used to detect the expression of four differentially expressed PIWI-interacting RNAs in 52 patients with acute myocardial infarction and 30 healthy people. Receiver operating characteristic (ROC) curve was further used to analyze the correlation between differentially expressed PIWI-interacting RNAs and the occurrence of acute myocardial infarction. Kyoto Encyclopedia of Genes and Genomes analysis was used to analyze the role of PIWI-interacting RNA in the occurrence of acute myocardial infarction.

RESULTS

RNA sequencing and bioinformatics analysis revealed that most piRNAs were upregulated in AMI patients, with 195 upregulated and 13 downregulated. Among them, piR-hsa-9010, piR-hsa-28646, and piR-hsa-23619 were significantly up-regulated in the serum of patients with acute myocardial infarction, but their expression in the acute heart failure group and coronary heart disease group was not significantly different from that in the healthy group. ROC curve analysis showed that piR-hsa-9010, piR-hsa-28646, and piR-hsa-23619 had high diagnostic values in acute myocardial infarction. In vitro, there was no significant difference in the expression of piR-hsa-9010 among THP-1, HUVEC, and AC16, while the expression of piR-hsa-28646 and piR-hsa-23619 in HUVEC was significantly higher than that in THP-1 and AC16. Pathway analysis showed that piR-hsa-23619 was mainly involved in TNF signaling pathway, and piR-hsa-28646 was mainly involved in Wnt signaling pathway.

CONCLUSION

piR-hsa-9010, piR-hsa-28646, and piR-hsa-23619 were significantly up-regulated in the serum of patients with acute myocardial infarction. It can be used as a new biomarker for the diagnosis of acute myocardial infarction, which may be a therapeutic target for acute myocardial infarction.

PiRNA in Cardiovascular Disease: Focus on Cardiac Remodeling and Cardiac Protection

Cardiovascular diseases (CVDs) are common causes of death, which take about 18.6 million lives worldwide every year. Currently, exploring strategies that delay ventricular remodeling, reduce cardiomyocyte death, and promote cardiomyocyte regeneration has been the hotspot and difficulty of the ischemic heart disease (IHD) research field. Previous studies indicate that piwi-interacting RNA (piRNA) plays a vital role in the occurrence and development of cardiac remodeling and may offer novel therapeutic strategies for cardiac repair. The best-known biological function of piRNA is to silence transposons in cells. In the cardiovascular system, piRNA is known to participate in cardiac progenitor cell proliferation, AKT pathway regulation, and cardiac remodeling and decompensation. In this review, we systematically discuss the research progress on piRNA in CVDs, especially the mechanism of cardiac remodeling and the potential functions in cardiac protection, which provides new insights for the progress and treatment of cardiovascular diseases. Piwi-interacting RNA (piRNA) is one of the noncoding RNAs, with the best -known biological function to silence transposons in cells. Now piRNA is found to participate in cardiac progenitor cell proliferation, AKT pathway regulation, cardiac remodeling and decompensation, which implies the potential of piRNA in the diagnosis and treatment of cardiovascular diseases. Over expression of piRNA could promote cardiac apoptosis and cardiac hypertrophy, thus targeted therapy which inhibits expression of associated piRNA may reduce cardiac remodeling and reduce inflammation caused by necrotic cardiomyocytes. PiRNA is also speculated to participate in the proliferation of cardiac progenitor cells, implying the potential to induce cardiac regeneration th erapy, which provides new insights for treatment of cardiovascular diseases. At present, the treatment strategy of cardiac remodeling emphasizes the control of risk factors, prevention of disease progression and individualized treatment. With further studies in mechanism of piRNA, potential therapies above may come true and more therapies in cardiovascular diseases may be found.

PIWI-interacting RNAs: Critical roles and therapeutic targets in cancer

P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) are a novel class of small regulatory RNAs (approximately 24-31 nucleotides in length) that often bind to members of the PIWI protein family. piRNAs regulate transposons in animal germ cells; piRNAs are also specifically expressed in many human tissues and regulate pivotal signaling pathways. Additionally, the abnormal expression of piRNAs and PIWI proteins has been associated with various malignant tumours, and multiple mechanisms of piRNA-mediated target gene dysregulation are involved in tumourigenesis and progression, suggesting that they have the potential to serve as new biomarkers and therapeutic targets for tumours. However, the functions and potential mechanisms of action of piRNAs in cancer have not yet been elucidated. This review summarises the current findings on the biogenesis, function, and mechanisms of piRNAs and PIWI proteins in cancer. We also discuss the clinical significance of piRNAs as diagnostic or prognostic biomarkers and therapeutic tools for cancer. Finally, we present some critical questions regarding piRNA research that need to be addressed to provide insight into the future development of the field.

PIWI-Interacting RNA (piRNA) and Epigenetic Editing in Environmental Health Sciences

PURPOSE OF REVIEW: The epigenome modulates gene expression in response to environmental stimuli. Modifications to the epigenome are potentially reversible, making them a promising therapeutic approach to mitigate environmental exposure effects on human health. This review details currently available genome and epigenome editing technologies and highlights ncRNA, including piRNA, as potential tools for targeted epigenome editing. RECENT FINDINGS: Zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN), and clustered regularly interspaced short palindromic repeats (CRISPR) associated nuclease (CRISPR/Cas) research has significantly advanced genome editing technology, with broad promise in genetic research and targeted therapies. Initial epigenome-directed therapies relied on global modification and suffered from limited specificity. Adapted from current genome editing tools, zinc finger protein (ZFP), TALE, and CRISPR/nuclease-deactivated Cas (dCas) systems now confer locus-specific epigenome editing, with promising applicability in the field of environmental health sciences. However, high incidence of off-target effects and time taken for screening limit their use. FUTURE DEVELOPMENT: ncRNA serve as a versatile biomarker with well-characterized regulatory mechanisms that can easily be adapted to edit the epigenome. For instance, the transposon silencing mechanism of germline PIWI-interacting RNAs (piRNA) could be engineered to specifically methylate a given gene, overcoming pitfalls of current global modifiers. Future developments in epigenome editing technologies will inform risk assessment through mechanistic investigation and serve as potential modes of intervention to mitigate environmentally induced adverse health outcomes later in life.

Mechanism of piR-1245/PIWI-like protein-2 regulating Janus kinase-2/signal transducer and activator of transcription-3/vascular endothelial growth factor signaling pathway in retinal neovascularization

Inhibiting retinal neovascularization is the optimal strategy for the treatment of retina-related diseases, but there is currently no effective treatment for retinal neovascularization. P-element-induced wimpy testis (PIWI)-interacting RNA (piRNA) is a type of small non-coding RNA implicated in a variety of diseases. In this study, we found that the expression of piR-1245 and the interacting protein PIWIL2 were remarkably increased in human retinal endothelial cells cultured in a hypoxic environment, and cell apoptosis, migration, tube formation and proliferation were remarkably enhanced in these cells. Knocking down piR-1245 inhibited the above phenomena. After intervention by a p-JAK2 activator, piR-1245 decreased the expression of hypoxia inducible factor-1α and vascular endothelial growth factor through the JAK2/STAT3 pathway. For in vivo analysis, 7-day-old newborn mice were raised in 75 ± 2% hyperoxia for 5 days and then piR-1245 in the retina was knocked down. In these mice, the number of newly formed vessels in the retina was decreased, the expressions of inflammation-related proteins were reduced, the number of apoptotic cells in the retina was decreased, the JAK2/STAT3 pathway was inhibited, and the expressions of hypoxia inducible factor-1α and vascular endothelial growth factor were decreased. Injection of the JAK2 inhibitor JAK2/TYK2-IN-1 into the vitreous cavity inhibited retinal neovascularization in mice and reduced expression of hypoxia inducible factor-1α and vascular endothelial growth factor. These findings suggest that piR-1245 activates the JAK2/STAT3 pathway, regulates the expression of hypoxia inducible factor-1α and vascular endothelial growth factor, and promotes retinal neovascularization. Therefore, piR-1245 may be a new therapeutic target for retinal neovascularization.

Respiratory syncytial virus infection changes the piwi-interacting RNA content of airway epithelial cells

Piwi-interacting RNAs (piRNAs) are small non-coding RNAs (sncRNAs) of about 26–32 nucleotides in length and represent the largest class of sncRNA molecules expressed in animal cells. piRNAs have been shown to play a crucial role to safeguard the genome, maintaining genome complexity and integrity, as they suppress the insertional mutations caused by transposable elements. However, there is growing evidence for the role of piRNAs in controlling gene expression in somatic cells as well. Little is known about changes in piRNA expression and possible function occurring in response to viral infections. In this study, we investigated the piRNA expression profile, using a human piRNA microarray, in human small airway epithelial (SAE) cells infected with respiratory syncytial virus (RSV), a leading cause of acute respiratory tract infections in children. We found a time-dependent increase in piRNAs differentially expressed in RSV-infected SAE cells. We validated the top piRNAs upregulated and downregulated at 24 h post-infection by RT-qPCR and identified potential targets. We then used Gene Ontology (GO) tool to predict the biological processes of the predicted targets of the most represented piRNAs in infected cells over the time course of RSV infection. We found that the most significant groups of targets of regulated piRNAs are related to cytoskeletal or Golgi organization and nucleic acid/nucleotide binding at 15 and 24 h p.i. To identify common patterns of time-dependent responses to infection, we clustered the significantly regulated expression profiles. Each of the clusters of temporal profiles have a distinct set of potential targets of the piRNAs in the cluster Understanding changes in piRNA expression in RSV-infected airway epithelial cells will increase our knowledge of the piRNA role in viral infection and might identify novel therapeutic targets for viral lung-mediated diseases.

Expression of Extracellular Vesicle PIWI-Interacting RNAs Throughout hiPSC-Cardiomyocyte Differentiation

Extracellular Vesicles (EV) play a critical role in the regulation of regenerative processes in wounded tissues by mediating cell-to-cell communication. Multiple RNA species have been identified in EV, although their function still lacks understanding. We previously characterized the miRNA content of EV secreted over hiPSC-cardiomyocyte differentiation and found a distinct miRNA expression in hiPSC-EV driving its in vitro bioactivity. In this work, we investigated the piRNA profiles of EV derived from key stages of the hiPSC-CM differentiation and maturation, i.e., from hiPSC (hiPSC-EV), cardiac progenitors (CPC-EV), immature (CMi-EV), and mature (CMm-EV) cardiomyocytes, demonstrating that EV-piRNA expression differs greatly from the miRNA profiles we previously identified. Only four piRNA were significantly deregulated in EV, one in hiPSC-EV, and three in CPC-EV, as determined by differential expression analysis on small RNA-seq data. Our results provide a valuable source of information for further studies aiming at defining the role of piRNA in the bioactivity and therapeutic potential of EV.

Current Understanding of piRNA in Cardiovascular Diseases

The relationship regarding non-coding genomes and cardiovascular disease (CVD) has been explored in the past decade. As one of the leading causes of death, there remains a lack of sensitive and specific genomic biomarkers in the diagnosis and prognosis of CVD. Piwi-interacting RNA (piRNA) is a group of small non-coding RNA (ncRNA) which associated with Piwi proteins. There is an emerging strong body of evidence in support of a role for ncRNAs, including piRNAs, in pathogenesis and prognosis of CVD. This article reviews the current evidence for piRNA-regulated mechanisms in CVD, which could lead to the development of new therapeutic strategies for prevention and treatment.

Technological Approaches in the Analysis of Extracellular Vesicle Nucleotide Sequences

Together with metabolites, proteins, and lipid components, the EV cargo consists of DNA and RNA nucleotide sequence species, which are part of the intracellular communication network regulating specific cellular processes and provoking distinct target cell responses. The extracellular vesicle (EV) nucleotide sequence cargo molecules are often investigated in association with a particular pathology and may provide an insight into the physiological and pathological processes in hard-to-access organs and tissues. The diversity and biological function of EV nucleotide sequences are distinct regarding EV subgroups and differ in tissue- and cell-released EVs. EV DNA is present mainly in apoptotic bodies, while there are different species of EV RNAs in all subgroups of EVs. A limited sample volume of unique human liquid biopsy provides a small amount of EVs with limited isolated DNA and RNA, which can be a challenging factor for EV nucleotide sequence analysis, while the additional difficulty is technical variability of molecular nucleotide detection. Every EV study is challenged with its first step of the EV isolation procedure, which determines the EV's purity, yield, and diameter range and has an impact on the EV's downstream analysis with a significant impact on the final result. The gold standard EV isolation procedure with ultracentrifugation provides a low output and not highly pure isolated EVs, while modern techniques increase EV's yield and purity. Different EV DNA and RNA detection techniques include the PCR procedure for nucleotide sequence replication of the molecules of interest, which can undergo a small-input EV DNA or RNA material. The nucleotide sequence detection approaches with their advantages and disadvantages should be considered to appropriately address the study problem and to extract specific EV nucleotide sequence information with the detection using qPCR or next-generation sequencing. Advanced next-generation sequencing techniques allow the detection of total EV genomic or transcriptomic data even at the single-molecule resolution and thus, offering a sensitive and accurate EV DNA or RNA biomarker detection. Additionally, with the processes where the EV genomic or transcriptomic data profiles are compared to identify characteristic EV differences in specific conditions, novel biomarkers could be discovered. Therefore, a suitable differential expression analysis is crucial to define the EV DNA or RNA differences between conditions under investigation. Further bioinformatics analysis can predict molecular cell targets and identify targeted and affected cellular pathways. The prediction target tools with functional studies are essential to help specify the role of the investigated EV-targeted nucleotide sequences in health and disease and support further development of EV-related therapeutics. This review will discuss the biological diversity of human liquid biopsy-obtained EV nucleotide sequences DNA and RNA species reported as potential biomarkers in health and disease and methodological principles of their detection, from human liquid biopsy EV isolation, EV nucleotide sequence extraction, techniques for their detection, and their cell target prediction.