Knowledge-based analysis of functional impacts of mutations in microRNA seed regions

microRNAs in sudden hearing loss

OBJECTIVES

To compare the circulating microRNA (miRNA) expression profiles between sudden sensory neural hearing loss (SSNHL) patients and age-matched normal hearing controls.

STUDY DESIGN

Prospective cohort multi-center study.

METHODS

Patients presenting within 28 days of onset of SSNHL were prospectively recruited along with contemporaneous age-matched controls. Pooled sera of four patient (n = 09, mean age = 53.0 years; 07, 55.0; 10, 52.9; 10, 51.6) and two control (09, 51.2 and 03, 50.0) groups were assessed using a TaqMan Low Density Array. The patients' sera were also divided into two pools, untreated (04, 57.7) and treated (32, 52.6) for additional analysis. miRNA expression level was derived from cycle threshold (Ct) values normalized to a global mean. Inter-group mean Ct differences with fold changes ≥2.0 and ≤0.5 at P < .05 were considered significant. Bioinformatic databases were used to identify putative target mRNAs or validated genes and their functional annotations.

RESULTS

Thirty-six SSNHL patients (mean age 53.0 ± standard deviation (SD) 15.2 years) and 12 controls (50.9 ± 11.9) were studied. Eight miRNAs hsa-miR-590-5p/ -186-5p/ -195-5p/ -140-3p/ -128-3p/ -132-3p/ -375-3p, and -30a-3p were identified as significantly differentially expressed in SSNHL patients. Most of these miRNAs were abundantly identified in the nervous system and the putative target messenger RNAs (mRNAs) were enriched in signaling pathways such as phosphatidyl inositol 3 kinase/protein Kinase B (PI3K/Akt), Ras and mitogen-activated protein kinase (MAPK).

CONCLUSION

These findings suggest the possible cellular signaling pathways that underlie the disruption of auditory signal transmission in SSNHL.

LEVEL OF EVIDENCE

2 Laryngoscope, 130:E416-E422, 2020.

TMPRSS3 regulates cell viability and apoptosis processes of HEI-OC1 cells via regulation of the circ-Slc4a2, miR-182 and Akt cascade

BACKGROUND

The present study aimed to investigate the functions and regulation mechanism of the transmembrane protease, serine 3 (TMPRSS3), which plays an important role in sensorineural hearing loss.

METHODS

House Ear Institute-Organ of Corti 1 (HEI-OC1) cells, comprising auditory-related cells, were used in the present study. An overexpression vector and small hairpin RNA target on TMPRSS3 were designed and transfected into HEI-OC1 cells. Circular RNA (circRNA) sequencing was conducted and expression profiles were obtained. The circular structure of circRNAs was validated with a polymerase chain reaction and Sanger sequencing using convergent and divergent primers.

RESULTS

Overexpression of TMPRSS3 increased cell viability, whereas suppression of TMPRSS3 increased the percentage of apoptotic cells and decreased cell viability, compared to the control group. circRNA sequencing provided expression profiles indicating that the overexpression of TMPRSS3 increased the expression level of 195 circRNAs. Results of GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) studies indicated that the circRNAs are focused on the RAS signaling pathway. The pathway, circ-Slc41a2 (chr10: 82744115|82767120), miR-182 and Akt, might comprise one of the key cascades of TMPRSS3.

CONCLUSIONS

TMPRSS3 is an important molecule in the regulation of cell viability and cell apoptosis of HEI-OC1 cells. Its functions are dependent on the circ-Slc41a2, miR-182 and Akt cascade.

Functional Analysis of Genetic Variants and Somatic Mutations Impacting MicroRNA-Target Recognition: Bioinformatics Resources

MicroRNAs are small noncoding RNA molecules with great importance in regulating a large number of diverse biological processes in health and disease. MicroRNAs can bind to both coding and noncoding RNAs and regulate their stability and expression. Genetic variants and somatic mutations may alter microRNA sequences and their target sites and therefore impact microRNA-target recognition. Aberrant microRNA-target interactions have been associated with many diseases. In recent years, computational resources have been developed for retrieving, annotating, and analyzing the impact of mutations on microRNA-target recognition. In this chapter, we provide an overview on the computational analysis of mutations impacting microRNA target recognition, followed by a detailed tutorial on how to use three major Web-based bioinformatics resources: PolymiRTS ( http://compbio.uthsc.edu/miRSNP ), a database of genetic variants impacting microRNA target recognition; SomamiR ( http://compbio.uthsc.edu/SomamiR ), a database of somatic mutations affecting the interactions between microRNAs and their targets in mRNAs and noncoding RNAs; and miR2GO ( http://compbio.uthsc.edu/miR2GO ), a computational tool for knowledge-based functional analysis of genetic variants and somatic mutations in microRNA seed regions.

Framework for microRNA variant annotation and prioritization using human population and disease datasets

MicroRNA (miRNA) expression is frequently deregulated in human disease, in contrast, disease-associated miRNA mutations are understudied. We developed Annotative Database of miRNA Elements, ADmiRE, which combines multiple existing and new biological annotations to aid prioritization of causal miRNA variation. We annotated 10,206 mature (3,257 within seed region) miRNA variants from multiple large sequencing datasets including gnomAD (15,496 genomes; 123,136 exomes). The pattern of miRNA variation closely resembles protein-coding exonic regions, with no difference between intragenic and intergenic miRNAs (P = 0.56), and high confidence miRNAs demonstrate higher sequence constraint (P < 0.001). Conservation analysis across 100 vertebrates identified 765 highly conserved miRNAs that also have limited genetic variation in gnomAD. We applied ADmiRE to the TCGA PanCancerAtlas WES dataset containing over 10,000 individuals across 33 adult cancers and annotated 1,267 germline (rare in gnomAD) and 1,492 somatic miRNA variants. Several miRNA families with deregulated gene expression in cancer have low levels of both somatic and germline variants, e.g., let-7 and miR-10. In addition to known somatic miR-142 mutations in hematologic cancers, we describe novel somatic miR-21 mutations in esophageal cancers impacting downstream miRNA targets. Through the development of ADmiRE, we present a framework for annotation and prioritization of miRNA variation in disease datasets.

The Mechanism of Synchronous Precise Regulation of Two Shrimp White Spot Syndrome Virus Targets by a Viral MicroRNA

MicroRNAs (miRNAs), important factors in animal innate immunity, suppress the expressions of their target genes by binding to target mRNA’s 3′ untranslated regions (3′UTRs). However, the mechanism of synchronous regulation of multiple targets by a single miRNA remains unclear. In this study, the interaction between a white spot syndrome virus (WSSV) miRNA (WSSV-miR-N32) and its two viral targets (wsv459 and wsv322) was characterized in WSSV-infected shrimp. The outcomes indicated that WSSV-encoded miRNA (WSSV-miR-N32) significantly inhibited virus infection by simultaneously targeting wsv459 and wsv322. The silencing of wsv459 or wsv322 by siRNA led to significant decrease of WSSV copies in shrimp, showing that the two viral genes were required for WSSV infection. WSSV-miR-N32 could mediate 5′–3′ exonucleolytic digestion of its target mRNAs, which stopped at the sites of target mRNA 3′UTRs close to the sequence complementary to the miRNA seed sequence. The complementary bases (to the target mRNA sequence) of a miRNA 9th–18th non-seed sequence were essential for the miRNA targeting. Therefore, our findings presented novel insights into the mechanism of miRNA-mediated suppression of target gene expressions, which would be helpful for understanding the roles of miRNAs in innate immunity of invertebrate.

MicroRNAs: effective elements in ear-related diseases and hearing loss

miRNAs are important factors for post-transcriptional process that controls gene expression at mRNA level. Various biological processes, including growth and differentiation, are regulated by miRNAs. miRNAs have been demonstrated to play an essential role in development and progression of hearing loss. Nowadays, miRNAs are known as critical factors involved in different physiological, biological, and pathological processes, such as gene expression, progressive sensorineural hearing loss, age-related hearing loss, noise-induced hearing loss, cholesteatoma, schwannomas, and inner ear inflammation. The miR-183 family (miR-183, miR-96 and miR-182) is expressed abundantly in some types of sensory cells in inner ear specially mechanosensory hair cells that exhibit a great expression level of this family. The plasma levels of miR-24-3p, miR-16-5p, miR-185-5p, and miR-451a were upregulated during noise exposures, and increased levels of miR-21 have been found in vestibular schwannomas and human cholesteatoma. In addition, upregulation of pro-apoptotic miRNAs and downregulation of miRNAs which promote differentiation and proliferation in age-related degeneration of the organ of Corti may potentially serve as a helpful biomarker for the early detection of age-related hearing loss. This knowledge represents miRNAs as promising diagnostic and therapeutic tools in the near future.

SomamiR 2.0: a database of cancer somatic mutations altering microRNA-ceRNA interactions

SomamiR 2.0 (http://compbio.uthsc.edu/SomamiR) is a database of cancer somatic mutations in microRNAs (miRNA) and their target sites that potentially alter the interactions between miRNAs and competing endogenous RNAs (ceRNA) including mRNAs, circular RNAs (circRNA) and long noncoding RNAs (lncRNA). Here, we describe the recent major updates to the SomamiR database. We expanded the scope of the database by including somatic mutations that impact the interactions between miRNAs and two classes of non-coding RNAs, circRNAs and lncRNAs. Recently, a large number of miRNA target sites have been discovered by newly emerged high-throughput technologies for mapping the miRNA interactome. We have mapped 388 247 somatic mutations to the experimentally identified miRNA target sites. The updated database also includes a list of somatic mutations in the miRNA seed regions, which contain the most important guiding information for miRNA target recognition. A recently developed webserver, miR2GO, was integrated with the database to provide a seamless pipeline for assessing functional impacts of somatic mutations in miRNA seed regions. Data and functions from multiple sources including biological pathways and genome-wide association studies were updated and integrated with SomamiR 2.0 to make it a better platform for functional analysis of somatic mutations altering miRNA–ceRNA interactions.