Expression analysis of microRNAs in murine cochlear explants

Epigenetic Modifications in Sensorineural Hearing Loss: Protective Mechanisms and Therapeutic Potential

Hearing loss, which currently affects more than 430 million individuals globally and is projected to exceed 700 million by 2050, predominantly manifests as sensorineural hearing loss (SNHL), for which existing technologies such as hearing aids and cochlear implants fail to restore natural auditory function. Research focusing on protecting inner ear hair cells (HCs) from harmful factors through the regulation of epigenetic modifications has gained significant attention in otology for its role in regulating gene expression without altering the DNA sequence, suggesting potential strategies for preventing and treating SNHL. By synthesizing relevant studies on the inner ear, this review summarizes the emerging roles of histone modifications, DNA methylation, and noncoding RNAs in HC damage, with a focus on their therapeutic potential through epigenetic modulation. Moreover, this review examines the therapeutic potential of epigenetic regulation for the prevention and treatment of SNHL, emphasizing the application of small-molecule epigenetic compounds and their efficacy in modulating gene expression to preserve and restore auditory function.

Long non-coding RNA NHEG1/hsa-miR-665/HMGB1 axis is involved in the regulation of neuroblastoma progression

Long non-coding (lncRNA) neuroblastoma highly expressed 1 (NHEG1) has been reorganized as a prognostic factor in neuroblastoma (NB), but the molecular mechanisms in the suppression of neuroblastoma remain to be elucidated. In our study, we explored the functional roles of lncRNA NHEG1 in neuroblastoma and the underlying molecular mechanism. We collected NB tumor samples and adjacent normal tissues to compare lncRNA NHEG1 expression. Through bioinformatic target prediction, we selected potential downstream effectors of lncRNA NHEG1 for functional validation in NB cell lines. We observed that lncRNA NHEG1 was significantly upregulated in NB tissues as compared to the normal tissues. In NB tissues, lncRNA NHEG1 expression showed an inverse correlation with hsa-miR-665 (miR-655), but a positive correlation with high mobility group box 1 (HMGB1). In NB cell lines, lncRNA NHEG1 knockdown caused the upregulation of miR-665 and the downregulation of HMGB1. Through a series of functional assays, we further demonstrated that lncRNA Nheg1 knockdown suppressed cell proliferation, migration and invasion of NB cells, which could be rescued by miR-665 inhibitor and HMGB1 overexpression. Together, our data demonstrated that lncRNA NHEG1 serves as a competitive partner to negatively regulate the activity of miR-665, which relieves the inhibition on HMGB1 expression and promotes the aggressive phenotype of neuroblastoma cells. Our study indicates that lncRNA NHEG1/miR-665/HMGB1 axis may play an important role in regulating the aggressiveness and the progression of neuroblastoma.

The miR-183/ItgA3 axis is a key regulator of prosensory area during early inner ear development

MicroRNAs are important regulators of gene expression and are involved in cellular processes such as proliferation or differentiation, particularly during development of numerous organs including the inner ear. However, it remains unknown if miRNAs are required during the earliest stages of otocyst and cochlear duct development. Here, we report that a conditional loss of Dicer expression in the otocyst impairs the early development of the inner ear as a result of the accumulation of DNA damage that trigger p53-mediated apoptosis. Moreover, cochlear progenitors in the prosensory domain do not exit the cell cycle. Our unbiased approach identified ItgA3 as a target of miR-183, which are both enriched in the otic vesicle. We observed that the repression of integrin alpha 3 by miR-183 controls cell proliferation in the developing cochlea. Collectively, our results reveal that Dicer and miRNAs play essential roles in the regulation of early inner ear development.

Non-coding RNAs in the development of sensory organs and related diseases

Genomes are transcribed well beyond the conventionally annotated protein-encoding genes and produce many thousands of regulatory non-coding RNAs (ncRNAs). In the last few years, ncRNAs, especially microRNAs and long non-coding RNA, have received increasing attention because of their implication in the function of chromatin-modifying complexes and in the regulation of transcriptional and post-transcriptional events. The morphological events and the genetic networks responsible for the development of sensory organs have been well delineated and therefore sensory organs have provided a useful scenario to address the role of ncRNAs. In this review, we summarize the current information on the importance of microRNAs and long non-coding RNAs during the development of the eye, inner ear, and olfactory system in vertebrates. We will also discuss those cases in which alteration of ncRNA expression has been linked to pathological conditions affecting these organs.