The DNA methylation inhibitor RG108 protects against noise-induced hearing loss

Application of self-assembly palladium single-atom nanozyme over polyoxometalates in protection against neomycin-induced hearing loss by inhibiting ferroptosis

Deafness mainly results from irreversible impairment of hair cells (HCs), which may relate to oxidative stress, yet therapeutical solutions is lacked due to limited understanding on the exact molecular mechanism. Herein, mimicking the molecular structure of natural enzymes, a palladium (Pd) single-atom nanozyme (SAN) was fabricated, exhibiting superoxide dismutase and catalase activity, transforming reactive oxygen species (ROS) into O2 and H2O. We examined the involvement of Pd in neomycin-induced HCs loss in vitro and in vivo over zebrafish. Our results revealed that neomycin treatment induced apoptosis in HCs, resulting in substantial of ROS elevation in HEI-OC1 cells, decrease in mitochondrial membrane potential, and increase in lipid peroxidation and iron accumulation, ultimately leading to iron-mediated cell death. Noteworthy, Pd SAN treatment exhibited significant protective effects against HCs damage and impaired HCs function in zebrafish by inhibiting ferroptosis. Furthermore, the application of iron death inducer RSL3 resulted in notable exacerbation of neomycin-induced harm, which was mitigated by Pd administration. Our investigation demonstrates that antioxidants is promising for inhibiting ferroptosis and repairing of mitochondrial function in HCs and the enzyme-mimic SAN provides a good strategy for designing drugs alleviating neomycin-induced ototoxicity.

Epigenetic reprogramming as a key to reverse ageing and increase longevity

The pursuit for the fountain of youth has long been a fascination amongst scientists and humanity. Ageing is broadly characterized by a cellular decline with increased susceptibility to age-related diseases, being intimately associated with epigenetic modifications. Recently, reprogramming-induced rejuvenation strategies have begun to greatly alter longevity research not only to tackle age-related defects but also to possibly reverse the cellular ageing process. Hence, in this review, we highlight the major epigenetic changes during ageing and the state-of-art of the current emerging epigenetic reprogramming strategies leveraging on transcription factors. Notably, partial reprogramming enables the resetting of the ageing clock without erasing cellular identity. Promising chemical-based rejuvenation strategies harnessing small molecules, including DNA methyltransferase and histone deacetylase inhibitors are also discussed. Moreover, in parallel to longevity interventions, the foundations of epigenetic clocks for accurate ageing assessment and evaluation of reprogramming approaches are briefly presented. Going further, with such scientific breakthroughs, we are witnessing a rise in the longevity biotech industry aiming to extend the health span and ideally achieve human rejuvenation one day. In this context, we overview the main scenarios proposed for the future of the socio-economic and ethical challenges associated with such an emerging field. Ultimately, this review aims to inspire future research on interventions that promote healthy ageing for all.

What can insects teach us about hearing loss?

Over the last three decades, insects have been utilized to provide a deep and fundamental understanding of many human diseases and disorders. Here, we present arguments for insects as models to understand general principles underlying hearing loss. Despite ∼600 million years since the last common ancestor of vertebrates and invertebrates, we share an overwhelming degree of genetic homology particularly with respect to auditory organ development and maintenance. Despite the anatomical differences between human and insect auditory organs, both share physiological principles of operation. We explain why these observations are expected and highlight areas in hearing loss research in which insects can provide insight. We start by briefly introducing the evolutionary journey of auditory organs, the reasons for using insect auditory organs for hearing loss research, and the tools and approaches available in insects. Then, the first half of the review focuses on auditory development and auditory disorders with a genetic cause. The second half analyses the physiological and genetic consequences of ageing and short- and long-term changes as a result of noise exposure. We finish with complex age and noise interactions in auditory systems. In this review, we present some of the evidence and arguments to support the use of insects to study mechanisms and potential treatments for hearing loss in humans. Obviously, insects cannot fully substitute for all aspects of human auditory function and loss of function, although there are many important questions that can be addressed in an animal model for which there are important ethical, practical and experimental advantages.

The Information Theory of Aging

Information storage and retrieval is essential for all life. In biology, information is primarily stored in two distinct ways: the genome, comprising nucleic acids, acts as a foundational blueprint and the epigenome, consisting of chemical modifications to DNA and histone proteins, regulates gene expression patterns and endows cells with specific identities and functions. Unlike the stable, digital nature of genetic information, epigenetic information is stored in a digital-analog format, susceptible to alterations induced by diverse environmental signals and cellular damage. The Information Theory of Aging (ITOA) states that the aging process is driven by the progressive loss of youthful epigenetic information, the retrieval of which via epigenetic reprogramming can improve the function of damaged and aged tissues by catalyzing age reversal.

GRAIL gene knockout mice protect against aging-related and noise-induced hearing loss

BACKGROUND

Hearing loss is a global health issue and its etiopathologies involve complex molecular pathways. The ubiquitin-proteasome system has been reported to be associated with cochlear development and hearing loss. The gene related to anergy in lymphocytes ( GRAIL ), as an E3 ubiquitin ligase, has not, as yet, been examined in aging-related and noise-induced hearing loss mice models.

METHODS

This study used wild-type (WT) and GRAIL knockout (KO) mice to examine cochlear hair cells and synaptic ribbons using immunofluorescence staining. The hearing in WT and KO mice was detected using auditory brainstem response. Gene expression patterns were compared using RNA-sequencing to identify potential targets during the pathogenesis of noise-induced hearing loss in WT and KO mice.

RESULTS

At the 12-month follow-up, GRAIL KO mice had significantly less elevation in threshold level and immunofluorescence staining showed less loss of outer hair cells and synaptic ribbons in the hook region compared with GRAIL WT mice. At days 1, 14, and 28 after noise exposure, GRAIL KO mice had significantly less elevation in threshold level than WT mice. After noise exposure, GRAIL KO mice showed less loss of outer hair cells in the cochlear hook and basal regions compared with WT mice. Moreover, immunofluorescence staining showed less loss of synaptic ribbons in the hook regions of GRAIL KO mice than of WT mice. RNA-seq analysis results showed significant differences in C-C motif chemokine ligand 19 ( CCL19 ), C-C motif chemokine ligand 21 ( CCL21 ), interleukin 25 ( IL25 ), glutathione peroxidase 6 ( GPX6 ), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 ( NOX1 ) genes after noise exposure.

CONCLUSION

The present data demonstrated that GRAIL deficiency protects against aging-related and noise-induced hearing loss. The mechanism involved needs to be further clarified from the potential association with synaptic modulation, inflammation, and oxidative stress.

Deciphering the potential ability of RG108 in cisplatin-induced HEI-OC1 ototoxicity: a research based on RNA-seq and molecular biology experiment

BACKGROUND

Drug-induced hearing loss (DIHL) is very common, and seriously affects people's happiness in life. RG108 is a small molecule inhibitor. RG108 is protective against DIHL. Our purpose is to probe the incidence of RG108 on cisplatin-induced ototoxicity.

MATERIALS AND METHODS

In our research, the ototoxicity of RG108 was investigated in HEI-OC1. We observed under the microscope whether RG108 had an effect on cisplatin-induced cochlear hair cells. RNA-seq experiments were further performed to explore possible gene ontology (GO) and pathways. ROS assay was applied to supervisory the effect of RG108 on oxidative harm of auditory cells. In auditory cells, RG108 was tested for its effects on apoptosis-related proteins by Western blotting (WB).

RESULTS

GO analysis showed that RG108 associated with apoptosis. KEGG analysis shows RG108 may act on PI3K-AKT signaling pathway (PASP) in hearing loss. BIOCARTA analysis showed that RG108 may affect oxidative stress by activating NRF2 pathway. ROS ascerted that RG108 could rescue oxidative harm in HEI-OC1. RG108 rescued cisplatin-induced significant increase in Bax and significant decrease in BCL2. RG108 attenuates cisplatin-induced cochlear apoptosis through upregulated phosphorylated PI3K and phosphorylated AKT and down-regulated caspase3. MTT experiments showed that both PI3K and AKT inhibitors could significantly rescue the damage caused by cisplatin to HEI-OC1. RG108 significantly increases the level of NRF2/HO-1/NQO1 in cisplatin-induced cells.

CONCLUSION

Overall, these results provide evidence that NRF2/PI3K-AKT axis may mediate RG108 in the treatment of DIHL, which provide a broader outlook on drug-induced deafness treatment.

Resveratrol prevents hearing loss and a subregion specific- reduction of serotonin reuptake transporter induced by noise exposure in the central auditory system

Prolonged or excessive exposure to noise can lead to hearing loss, tinnitus and hypersensitivity to sound. The effects of noise exposure on main excitatory and inhibitory neurotransmitter systems in auditory pathway have been extensively investigated. However, little is known about aberrant changes in neuromodulator systems caused by noise exposure. In the current study, we exposed 2-month-old mice to a narrow band noise at 116 dB SPL for 6 h or sham exposure, assessed auditory brainstem responses as well as examined the expression of serotonin reuptake transporter (SERT) in the cochlear nucleus (CN), inferior colliculus (IC), and primary auditory cortex (Au1) using immunohistochemistry. We found that noise exposure resulted in a significant increase in hearing thresholds at 4, 8, 16, 24, and 32 kHz, as well as led to a significant reduction of SERT in dorsal cochlear nucleus (DCN), dorsal IC (ICd), external IC (ICe), and Au1 layers I-IV. This reduction of SERT in these subregions of central auditory system was partially recovered 15 or 30 days after noise exposure. Furthermore, we examined efficacy of resveratrol (RSV) on hearing loss and loss of SERT induced by noise exposure. The results demonstrated that RSV treatment significantly attenuated threshold shifts of auditory brainstem responses and loss of SERT in DCN, ICd, ICe, and Au1 layers I-IV. These findings show that noise exposure can cause hearing loss and subregion-specific loss of SERT in the central auditory system, and RSV treatment could attenuate noise exposure-induced hearing loss and loss of SERT in central auditory system.

S100A8 and S100A12 Proteins as Biomarkers of High Disease Activity in Patients with Rheumatoid Arthritis That Can Be Regulated by Epigenetic Drugs

Rheumatoid arthritis (RA) is an autoimmune chronic inflammatory disease that is still not well understood in terms of its pathogenesis and presents diagnostic and therapeutic challenges. Monocytes are key players in initiating and maintaining inflammation through the production of pro-inflammatory cytokines and S100 proteins in RA. This study aimed to test a specific DNA methylation inhibitor (RG108) and activator (budesonide) in the regulation of pro-inflammatory mediators-especially the S100 proteins. We also searched for new biomarkers of high disease activity in RA patients. RNA sequencing analysis of healthy controls (HCs) and RA monocytes was performed. Genes such as the S100 family, TNF, and IL-8 were validated by qRT-PCR following DNA-methylation-targeted drug treatment in a monocytic THP-1 cell line. The concentrations of the S100A8, S100A11, and S100A12 proteins in the sera and synovial fluids of RA patients were tested and correlated with clinical parameters. We demonstrated that RA monocytes had significantly increased levels of S100A8, S100A9, S100A11, S100A12, MYD88, JAK3, and IQGAP1 and decreased levels of IL10RA and TGIF1 transcripts. In addition, stimulation of THP-1 cells with budesonide statistically reduced the expression of the S100 family, IL-8, and TNF genes. In contrast, THP-1 cells treated with RG108 had increased levels of the S100 family and TNF genes. We also revealed a significant upregulation of S100A8, S100A11, and S100A12 in RA patients, especially in early RA compared to HC sera. In addition, protein levels of S100A8, S100A11, and S100A12 in RA synovial fluids compared to HC sera were significantly increased. Overall, our data suggest that the S100A8 and S100A12 proteins are strongly elevated during ongoing inflammation, so they could be used as a better biomarker of disease activity than CRP. Interestingly, epigenetic drugs can regulate these S100 proteins, suggesting their potential use in targeting RA inflammation.

A PRMT5 inhibitor protects against noise-induced hearing loss by alleviating ROS accumulation

The aim of this study was to investigate the effect of LLY-283, a selective inhibitor of protein arginine methyltransferase 5 (PRMT5), on a noise-induced hearing loss (NIHL) mouse model and to identify a potential target for a therapeutic intervention against NIHL. Eight-week-old male C57BL/6 mice were used. The auditory brainstem response was measured 2 days after noise exposure. The apoptosis of hair cells (HCs) was detected by caspase-3/7 staining, whereas the accumulation of reactive oxygen species (ROS) was measured by 4-HNE staining. We demonstrated that the death of HCs and loss of cochlear synaptic ribbons induced by noise exposure could be significantly reduced by the presence of LLY-283. LLY-283 pretreatment before noise exposure notably decreased 4-HNE and caspase-3/7 levels in the cochlear HCs. We also noticed that the number of spiral ganglion neurons (SGNs) was notably increased after LLY-283 pretreatment. Furthermore, we showed that LLY-283 could increase the expression level of p-AKT in the SGNs. The underlying mechanism involves alleviation of ROS accumulation and activation of the PI3K/AKT pathway, indicating that LLY-283 might be a potential candidate for therapeutic intervention against NIHL.

Dnmt1 is required for the development of auditory organs via cell cycle arrest and Fgf signalling

Objectives

To explore the role of DNA methyltransferase 1 (DNMT1) in the development of auditory system using zebrafish as experimental model.

Methods

Morpholino oligonucleotide was used to induce Dnmt1 deficiency. RNA sequencing, in situ hybridization (ISH), whole genomic bisulfide sequencing (WGBS) and immunostaining were used to investigate the morphologic alterations and mechanisms.

Results

We found that downregulation of Dnmt1 induced decreased number of neuromasts and repressed cell proliferation of primordium in the developing posterior lateral line system of zebrafish. The ISH data uncovered that Fgf signalling pathway was inhibited and the expression of chemokine members cxcr4b, cxcr7b and cxcl12a were interfered, while lef1 expression was increased after inhibiting Dnmt1. Additionally, Dnmt1 downregulation led to malformed otoliths and deformed semicircular canals, and hair cell differentiation in utricle and saccule was inhibited severely. The in situ staining of otic placode markers pax2/5 and fgf 3/8/10 was decreased when Dnmt1 downregulated. The WGBS analysis demonstrated that the global methylation status was markedly downregulated, and cell cycle genes were among those most differently expressed between Dnmt1 morphants and the controls. Further ISH analysis confirmed the findings by RNA‐seq and WGBS assay that cdkn1a and tp53 were both upregulated after knockdown of Dnmt1.

Conclusion

Our results revealed that Dnmt1 is essential for the development of zebrafish auditory organ through regulating cell cycle genes together with Wnt and Fgf signalling pathways.

DNA Methylation of T Lymphocytes as a Therapeutic Target: Implications for Rheumatoid Arthritis Etiology

Rheumatoid arthritis (RA) is an autoimmune disease that can cause joint damage and disability. Epigenetic variation, especially DNA methylation, has been shown to be involved in almost all the stages of the pathology of RA, from autoantibody production to various self-effector T cells and the defects of protective T cells that can lead to chronic inflammation and erosion of bones and joints. Given the critical role of T cells in the pathology of RA, the regulatory functions of DNA methylation in T cell biology remain unclear. In this review, we elaborate on the relationship between RA pathogenesis and DNA methylation in the context of different T cell populations. We summarize the relevant methylation events in T cell development, differentiation, and T cell-related genes in disease prediction and drug efficacy. Understanding the epigenetic regulation of T cells has the potential to profoundly translate preclinical results into clinical practice and provide a framework for the development of novel, individualized RA therapeutics.