PIN1 Protects Hair Cells and Auditory HEI-OC1 Cells against Senescence by Inhibiting the PI3K/Akt/mTOR Pathway

The chromatin accessibility and transcriptomic landscape of the aging mice cochlea and the identification of potential functional super-enhancers in age-related hearing loss

BACKGROUND

Presbycusis, also referred to as age-related hearing loss (ARHL), is a condition that results from the cumulative effects of aging on an individual's auditory capabilities. Given the limited understanding of epigenetic mechanisms in ARHL, our research focuses on alterations in chromatin-accessible regions.

METHODS

We employed assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) in conjunction with unique identifier (UID) mRNA-seq between young and aging cochleae, and conducted integrated analysis as well as motif/TF-gene prediction. Additionally, the essential role of super-enhancers (SEs) in the development of ARHL was identified by comparative analysis to previous research. Meanwhile, an ARHL mouse model and an aging mimic hair cell (HC) model were established with a comprehensive identification of senescence phenotypes to access the role of SEs in ARHL progression.

RESULTS

The control cochlear tissue exhibited greater chromatin accessibility than cochlear tissue affected by ARHL. Furthermore, the levels of histone 3 lysine 27 acetylation were significantly depressed in both aging cochlea and aging mimic HEI-OC1 cells, highlighting the essential role of SEs in the development of ARHL. The potential senescence-associated super-enhancers (SASEs) of ARHL were identified, most of which exhibited decreased chromatin accessibility. The majority of genes related to the SASEs showed obvious decreases in mRNA expression level in aging HCs and was noticeably altered following treatment with JQ1 (a commonly used SE inhibitor).

CONCLUSION

The chromatin accessibility in control cochlear tissue was higher than that in cochlear tissue affected by ARHL. Potential SEs involved in ARHL were identified, which might provide a basis for future therapeutics targeting SASEs related to ARHL.

Is autism a PIN1 deficiency syndrome? A proposed etiological role for glyphosate

Autism is a neurodevelopmental disorder, the prevalence of which has increased dramatically in the United States over the past two decades. It is characterized by stereotyped behaviors and impairments in social interaction and communication. In this paper, we present evidence that autism can be viewed as a PIN1 deficiency syndrome. Peptidyl-prolyl cis/trans isomerase, NIMA-Interacting 1 (PIN1) is a peptidyl-prolyl cis/trans isomerase, and it has widespread influences in biological organisms. Broadly speaking, PIN1 deficiency is linked to many neurodegenerative diseases, whereas PIN1 over-expression is linked to cancer. Death-associated protein kinase 1 (DAPK1) strongly inhibits PIN1, and the hormone melatonin inhibits DAPK1. Melatonin deficiency is strongly linked to autism. It has recently been shown that glyphosate exposure to rats inhibits melatonin synthesis as a result of increased glutamate release from glial cells and increased expression of metabotropic glutamate receptors. Glyphosate's inhibition of melatonin leads to a reduction in PIN1 availability in neurons. In this paper, we show that PIN1 deficiency can explain many of the unique morphological features of autism, including increased dendritic spine density, missing or thin corpus callosum, and reduced bone density. We show how PIN1 deficiency disrupts the functioning of powerful high-level signaling molecules, such as nuclear factor erythroid 2-related factor 2 (NRF2) and p53. Dysregulation of both of these proteins has been linked to autism. Severe depletion of glutathione in the brain resulting from chronic exposure to oxidative stressors and extracellular glutamate leads to oxidation of the cysteine residue in PIN1, inactivating the protein and further contributing to PIN1 deficiency. Impaired autophagy leads to increased sensitivity of neurons to ferroptosis. It is imperative that further research be conducted to experimentally validate whether the mechanisms described here take place in response to chronic glyphosate exposure and whether this ultimately leads to autism.

Identification and experimental validation of ferroptosis-related gene lactotransferrin in age-related hearing loss

Objective

To reveal the relationship between ARHL and ferroptosis and screen ferroptosis-related genes (FRGs) in ARHL.

Methods

Bioinformatics were used to analyze the hub genes and molecular mechanism of ferroptosis in the aging cochleae. Senescence β-galactosidase staining, iron content detection, and micro malondialdehyde (MDA) assay kits were used to measure β-galactosidase activity, and expression of Fe2+ and MDA, respectively. Fluorescence microscope was used for immunofluorescence assay of hub genes. Western blot was used to verify the expression of hub genes in HEI-OC1 cells, cochlear explants, and cochleae of C57BL/6J mice. Data were expressed as mean ± SD of at least three independent experiments.

Results

The analysis of bioinformatics confirmed that lactotransferrin (LTF) is the hub gene and CEBPA-miR-130b-LTF network is the molecular mechanism for cochlear ferroptosis. Compared with the control group, the experiments proved that the indicators of ferroptosis, including Fe2+, MDA, and LTF were differentially expressed in aging HEI-OC1 cells, aging cochlear explants, and aging cochleae.

Conclusion

These results demonstrate that ferroptosis plays an important role in ARHL, and LTF is a potential therapeutic target for ARHL via regulating cochlear ferroptosis.

Artesunate alleviates 5-fluorouracil-induced intestinal damage by suppressing cellular senescence and enhances its antitumor activity

BACKGROUND

Colorectal cancer (CRC) is one of the most prevalent diagnosed malignancies and one of the leading causes of cancer-related deaths worldwide. 5-Fluorouracil (5-FU) and its combination regimen are commonly used as primary chemotherapeutic agents for advanced CRC. Intestinal mucositis is one of the most frequent side effects of 5-FU. Artesunate (Arte) is derived from the wormwood plant Artemisia annua. Arte is not only effective against malaria but also diabetes, atherosclerosis, inflammation, and other conditions. The mechanism by which 5-FU damages the intestinal tract is unclear, and there is no standard treatment for diarrhea caused by 5-FU. Therefore, it is critical to discover novel and promising therapeutic drugs for 5-FU side effect treatment.

METHODS

The morphology and expression of genes and proteins associated with the aging of HUVECs, HIECs, and intestinal tissues were compared to the those of the control group. The cell lines and tissues were evaluated by SA-β-Gal staining, Western blotting, and RT‒qPCR. HIEC and HCT116 cell viability was assessed in vitro by a CCK-8 assay and in vivo by a subcutaneous tumor mouse assay. Tumor cell proliferation and apoptosis was evaluated by immunohistochemistry.

RESULTS

Here, we report that Arte alleviates the adverse side effects caused by 5-FU in intestinal tissue, and that 5-FU-induced intestinal damage is associated with drug-induced chemical inflammation and an increase in the proportion of senescent cells. Arte decreases the ratio of SA-β-Gal-positive cells and downregulated the expression of aging-related proteins (p53, p16) and aging-related genes (p53, p21). Mechanistically, Arte relieves intestinal injury by inhibiting mTOR expression, which is associated with the regulation of aging. Moreover, Arte suppresses the p38MAPK and NF-κB signaling pathways, which are related to inflammation regulation. In addition, the combined therapy of Arte plus 5-FU significantly decreases cancer cell viability in vitro. Arte and 5-FU synergistically reduce the growth of colorectal cancer (CRC) xenografts in vivo.

CONCLUSIONS

Overall, our findings point to the crucial treatment effect of Arte on inflammation, intestinal cell senescence, and CRC cell proliferation and offer a new option for CRC treatment.

UCHL1 regulated by Sp1 ameliorates cochlear hair cell senescence and oxidative damage

Age-related hearing loss (ARHL) is the most common cause of hearing loss in the elderly. Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme involved in several types of human disease. The present study aimed to investigate the effect of UCHL1 on a hydrogen peroxide (H₂O₂)-induced ARHL model in cochlear hair cells and uncover its underlying mechanism. Reverse transcription-quantitative (RT-q)PCR and western blot analysis were used to assess UCHL1 expression in HEI-OC1 cells exposed to H₂O₂. Following UCHL1 overexpression in H₂O₂-induced HEI-OC1 cells, cell activity was assessed by Cell Counting Kit-8 assay. The content of oxidative stress-associated markers including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and reactive oxygen species (ROS ) was measured using corresponding commercial kits. Cell apoptosis was evaluated by TUNEL assay and western blot analysis. Cell senescence was assessed by senescence-associated β-galactosidase staining and western blot analysis. RT-qPCR and western blot analysis were applied to measure mRNA and protein expression levels, respectively, of specificity protein 1 (Sp1) in H₂O₂-treated HEI-OC1 cells. In addition, the association between UCHL1 and Sp1 was verified by luciferase reporter and chromatin immunoprecipitation (ChIP) assay. The mRNA and protein expression levels of UCHL1 were also determined in Sp1-overexpressing cells by RT-qPCR and western blot analysis, respectively. Following Sp1 overexpression in UCHL1-overexpressing H₂O₂-treated HEI-OC1 cells, cell activity, oxidative stress, apoptosis and senescence were assessed. Finally, the expression levels of NF-κB signaling-related proteins p-NF-κB p65 and NF-κB p65 were detected using western blot analysis. The results showed that UCHL1 was downregulated in H₂O₂-treated HEI-OC1 cells. In addition, UCHL1 overexpression enhanced cell viability and promoted oxidative damage, apoptosis and senescence in H₂O₂-induced HEI-OC1 cells. Furthermore, Sp1 was upregulated in H₂O₂-treated HEI-OC1 cells. Additionally, luciferase reporter and ChIP assays demonstrated that Sp1 interacted with the UCHL1 promoter to inhibit UCHL1 transcription. Sp1 overexpression reversed the effect of UCHL1 overexpression on cell viability, oxidative stress, apoptosis, senescence and activation of the NF-κB signaling pathway in H₂O_2-exposed HEI-OC1 cells. Collectively, the results suggested that UCHL1 transcriptional suppression by Sp1 protected cochlear hair cells from H₂O₂-triggered senescence and oxidative damage.

Network pharmacology and experimental evidence reveal the protective mechanism of Yi-Qi Cong-Ming decoction on age-related hearing loss

CONTEXT

Yi-Qi Cong-Ming (YQCM) decoction has been widely used to prevent age-related hearing loss (ARHL), the most prevalent neurodegenerative disease in the elderly.

OBJECTIVE

To explore the mechanism of YQCM decoction in the treatment of ARHL.

MATERIALS AND METHODS

The chemical constituents of YQCM were screened from the Traditional Chinese Medicine Systems Pharmacology Database. Potential targets of YQCM against ARHL were predicted by DrugBank, GeneCards, and OMIM database. Protein-protein network and enrichment analysis were used for exploring possible molecular mechanisms. Molecular docking and an in vitro model of ARHL by exposing auditory cells with 100 μM H₂O₂ for 3 h were applied. Cell viability and mitochondrial membrane potential (ΔΨM) were detected by CCK-8 and high-content analysis. γH2AX and cleaved caspase-3 were detected by Western blot.

RESULTS

The main compounds have good affinities with hub targets, especially AKT1, PTGS2, and CASP3. GO and KEGG analysis showed that the main biological process and key targets were related to negative regulation of the apoptotic process. H₂O₂ treatment could reduce the cell viability by 68% and impaired ΔΨM, while 90 μg/mL YQCM pre-treatment could restore the cell viability by 97.45% and increase ΔΨM (2-fold higher). YQCM pre-treatment also reduced γH2AX and cleaved caspase-3 protein levels.

CONCLUSIONS

Our study suggested that YQCM prevents ARHL by modulating the apoptosis process in auditory hair cells. Moreover, this study proved that bioinformatics analysis combined with molecular docking and cell model is a promising method to explore other possible pharmacological interventions of ARHL.

mTOR Signaling in BDNF-Treated Guinea Pigs after Ototoxic Deafening

The mammalian target of rapamycin (mTOR) signaling plays a critical role in cell homeostasis, growth and survival. Here, we investigated the localization of the main mTOR signaling proteins in the organ of Corti of normal-hearing and deafened guinea pigs, as well as their possible modulation by exogenously administered brain-derived neurotrophic factor (BDNF) in deafened guinea pigs. Animals were ototoxically deafened by systemic administration of kanamycin and furosemide, and one week later, the right cochleas were treated with gelatin sponge soaked in rhBDNF, while the left cochleas were used as negative controls. Twenty-four hours after treatment, animals were euthanized, and the cochleas were processed for subsequent analysis. Through immunofluorescence, we demonstrated the localization of AKT, pAKT, mTOR, pmTOR and PTEN proteins throughout the cochlea of guinea pigs for the first time, with a higher expression in supporting cells. Moreover, an increase in mTOR immunostaining was observed in BDNF-treated cochleas by means of fluorescence intensity compared to the other groups. Conversely, Western blot analysis showed no significant differences in the protein levels between groups, probably due to dilution of proteins in the neighboring tissues of the organ of Corti. Altogether, our data indicate that mTOR signaling proteins are expressed by the organ of Corti (with a major role for supporting cells) and that the modulation of mTOR may be a protective mechanism triggered by BDNF in the degenerating organ of Corti.

PIN1 protects auditory hair cells from senescence via autophagy

Background

Age-related hearing loss is an increasing sensorineural hearing loss. But the pathogenesis of ARHL has not been clarified. Herein, we studied the role and significance of PIN1 in regulating autophagy activity in senescence HEI-OC1cells and HCs.

Methods and Results

C57BL/6 mice and HEI-OC1 cells were contained in our research. Transfection of plasmids and juglone were used to upregulate or inhibit the PIN 1 expression. Immunofluorescence and Western blot were used to detect the expression of PIN1, LC3, p62, p21 and p16 protein levels in the hair cells of C57BL/6 mice cochleae and HEI-OC1 cells. Senescence-associated β-galactosidase (SA-β-gal) staining was used to investigate the senescent level.The results of this study showed that the level of autophagy increased in the senescent auditory hair cells. When inhibited the autophagy level with 3-MA, the senescent HEI-OC1 cells were alleviated. The autophagy activity in senescent HEI-OC1 cells also could be reduced by overexpressing PIN1 protein. On the contrary, inhibiting PIN1 could increase the autophagy level of senescent cells and cochlear hair cells.

Conclusion

PIN1 might regulate autophagy activity to induce the senescent of HEI-OC1cells and HCs, which will provide a theoretical support for the prevention and treatment of age-related hearing loss.

The role of peptidyl-prolyl isomerase Pin1 in neuronal signaling in epilepsy

Epilepsy is a common symptom of many neurological disorders and can lead to neuronal damage that plays a major role in seizure-related disability. The peptidyl-prolyl isomerase Pin1 has wide-ranging influences on the occurrence and development of neurological diseases. It has also been suggested that Pin1 acts on epileptic inhibition, and the molecular mechanism has recently been reported. In this review, we primarily focus on research concerning the mechanisms and functions of Pin1 in neurons. In addition, we highlight the significance and potential applications of Pin1 in neuronal diseases, especially epilepsy. We also discuss the molecular mechanisms by which Pin1 controls synapses, ion channels and neuronal signaling pathways to modulate epileptic susceptibility. Since neurotransmitters and some neuronal signaling pathways, such as Notch1 and PI3K/Akt, are vital to the nervous system, the role of Pin1 in epilepsy is discussed in the context of the CaMKII-AMPA receptor axis, PSD-95-NMDA receptor axis, NL2/gephyrin-GABA receptor signaling, and Notch1 and PI3K/Akt pathways. The effect of Pin1 on the progression of epilepsy in animal models is discussed as well. This information will lead to a better understanding of Pin1 signaling pathways in epilepsy and may facilitate development of new therapeutic strategies.

Potential therapeutic role of SIRT1 in age- related hearing loss

Age-related hearing loss (ARHL) is a major public health burden worldwide that profoundly affects the daily life of elderly people. Silent information regulator 1 (SIRT1 or Sirtuin1), known as a regulator of the cell cycle, the balance of oxidation/antioxidant and mitochondrial function, has been proven to have anti-aging and life-extending effects, and its possible connection with ARHL has received increasing attention in recent years. This paper provides an overview of research on the connection between SIRT1 and ARHL. Topics cover both the functions of SIRT1 and its important role in ARHL. This review concludes with a look at possible research directions for ARHL in the future.

PIN1-mediated ROS production is involved in antagonism of N-acetyl-L-cysteine against arsenic-induced hepatotoxicity

Arsenic, a widely existing environmental contaminant, is recognized to be toxic to multiple organs. Exposure to arsenic results in liver damage via excessive production of reactive oxidative species (ROS). PIN1 regulates the levels of ROS. N-acetyl-L-cysteine (NAC) is an ROS scavenger that protects the hepatic functions. Whether PIN1 plays a regulatory role in NAC-mediated antagonism against arsenic hepatotoxicity remains largely unknown. In our study, the protective effects of NAC against arsenic (NaAsO2)-induced hepatotoxicity were evaluated in vitro and in vivo. Arsenic exposure induced cytotoxicity by increasing the intracellular ROS production, impairing mitochondrial function and inducing apoptosis in L02 hepatocytes. Overexpression of PIN1 markedly protected against arsenic cytotoxicity, decreased ROS levels, and mitigated mitochondrial dysfunction and apoptosis in L02 cells. However, loss of PIN1 further aggravated arsenic-induced cytotoxicity and abolished the protective effects of NAC in L02 cells. An in vivo study showed that pretreatment with NAC rescued arsenic-induced liver injury by restoring liver function and suppressing hepatic oxidative stress. Overexpression of PIN1 in mice transfected with AAV-Pin1 relieved arsenic-induced liver dysfunction and hepatic oxidative stress. Taken together, our study identified PIN1 as a novel intervention target for antagonizing arsenic-induced hepatotoxicity, highlighting a new pharmacological mechanism of NAC targeting PIN1 in antagonism against arsenic toxicity.

Pyrroloquinoline quinone (PQQ) protects mitochondrial function of HEI-OC1 cells under premature senescence

The aim of this study was to investigate the effects of pyrroloquinoline quinone (PQQ), an oxidoreductase cofactor, on the H₂O₂-induced premature senescence model in HEI-OC1 auditory cells and to elucidate its mechanism of action in vitro. Cells were treated with PQQ for 1 day before H₂O₂ (100 μM) exposure. Mitochondrial respiratory capacity was damaged in this premature senescence model but was restored in cells pretreated with PQQ (0.1 nM or 1.0 nM). A decrease in mitochondrial potential, the promotion of mitochondrial fusion and the accelerated movement of mitochondria were all observed in PQQ-pretreated cells. The protein expression of sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) were significantly decreased under H₂O₂ exposure while they were increased with PQQ pretreatment, and PGC-1α acetylation was significantly decreased. In conclusion, PQQ has a protective effect on the premature senescence model of HEI-OC1 auditory cells and is associated with the SIRT1/PGC-1α signaling pathway, mitochondrial structure, and mitochondrial respiratory capacity.

Prediction of the Molecular Mechanisms Underlying Erlong Zuoci Treatment of Age-Related Hearing Loss via Network Pharmacology-Based Analyses Combined with Experimental Validation

Background: The traditional Chinese medicine formula ErLong ZuoCi (ELZC) has been extensively used to treat age-related hearing loss (ARHL) in clinical practice in China for centuries. However, the underlying molecular mechanisms are still poorly understood.

Objective: Combine network pharmacology with experimental validation to explore the potential molecular mechanisms underlying ELZC with a systematic viewpoint.

Methods: The chemical components of ELZC were collected from the Traditional Chinese Medicine System Pharmacology database, and their possible target proteins were predicted using the SwissTargetPrediction database. The putative ARHL-related target proteins were identified from the database: GeneCards and OMIM. We constructed the drug-target network as well as drug-disease specific protein-protein interaction networks and performed clustering and topological property analyses. Functional annotation and signaling pathways were performed by gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis. Finally, in vitro experiments were also performed to validate ELZC’s key target proteins and treatment effects on ARHL.

Results: In total, 63 chemical compounds from ELZC and 365 putative ARHL-related targets were identified, and 1860 ARHL-related targets were collected from the OMIM and GeneCards. A total of 145 shared targets of ELZC and ARHL were acquired by Venn diagram analysis. Functional enrichment analysis suggested that ELZC might exert its pharmacological effects in multiple biological processes, such as cell proliferation, apoptosis, inflammatory response, and synaptic connections, and the potential targets might be associated with AKT, ERK, and STAT3, as well as other proteins. In vitro experiments revealed that ELZC pretreatment could decrease senescence-associated β-galactosidase activity in hydrogen peroxide-induced auditory hair cells, eliminate DNA damage, and reduce cellular senescence protein p21 and p53. Finally, Western blot analysis confirmed that ELZC could upregulate the predicted target ERK phosphorylation.

Conclusion: We provide an integrative network pharmacology approach, in combination with in vitro experiments to explore the underlying molecular mechanisms governing ELZC treatment of ARHL. The protective effects of ELZC against ARHL were predicted to be associated with cellular senescence, inflammatory response, and synaptic connections which might be linked to various pathways such as JNK/STAT3 and ERK cascade signaling pathways. As a prosperous possibility, our experimental data suggest phosphorylation ERK is essential for ELZC to prevent degeneration of cochlear.