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FASEB Journal : Official Publication of... Nov 2023Vision loss and blindness are frequently caused by photoreceptor degeneration, for example in age-related macular degeneration and retinitis pigmentosa. However, there...
Vision loss and blindness are frequently caused by photoreceptor degeneration, for example in age-related macular degeneration and retinitis pigmentosa. However, there is no effective medicine to treat these photoreceptor degeneration-related diseases. Cell senescence is a common phenotype in many diseases; however, few studies have reported whether it occurs in photoreceptor degeneration diseases. Herein, we identified that cell senescence is associated with photoreceptor degeneration induced by N-methyl-N-nitrosourea (MNU, a commonly used photoreceptor degeneration model), presented as increased senescence-associated β-galactosidase activity, DNA damage, oxidative stress and inflammation-related cytokine Interleukin 6 (IL6), and upregulation of cyclin p21 or p16. These results suggested that visual function might be protected using anti-aging treatment. Furthermore, Hyperoside is reported to help prevent aging in various organs. In this study, we showed that Hyperoside, delivered intravitreally, alleviated photoreceptor cell senescence and ameliorated the functional and morphological degeneration of the retina in vivo and in vitro. Importantly, Hyperoside attenuated the MNU-induced injury and aging of photoreceptors via AMPK-ULK1 signaling inhibition. Taken together, our results demonstrated that Hyperoside can prevent MNU-induced photoreceptor degeneration by inhibiting cell senescence via the AMPK-ULK1 pathway.
Topics: Animals; AMP-Activated Protein Kinases; Apoptosis; Cellular Senescence; Disease Models, Animal; Methylnitrosourea; Photoreceptor Cells, Vertebrate; Retina; Retinal Degeneration
PubMed: 37819682
DOI: 10.1096/fj.202301273RR -
Molecular Biology Reports Jun 2024Sn1-type alkylating agents methylate the oxygen atom on guanine bases thereby producing O-methylguanine. This modified base could pair with thymine and cytosine,...
BACKGROUND
Sn1-type alkylating agents methylate the oxygen atom on guanine bases thereby producing O-methylguanine. This modified base could pair with thymine and cytosine, resulting in the formation of O-methylguanine/thymine mismatch during DNA replication, recognized by the mismatch repair (MMR) complex, which then initiates the DNA damage response and subsequent apoptotic processes. In our investigation of the molecular mechanisms underlying MMR-dependent apoptosis, we observed FANCD2 modification upon the activity of alkylating agent N-methyl-N-nitrosourea (MNU). This observation led us to hypothesize a relevant role for FANCD2 in the apoptosis induction process.
METHODS AND RESULTS
We generated FANCD2 knockout cells using the CRISPR/Cas9 method in the human cervical cancer cell line HeLa MR. FANCD2-deficient cells exhibited MNU hypersensitivity. Upon MNU exposure, FANCD2 colocalized with the MMR complex. MNU-treated FANCD2 knockout cells displayed severe S phase delay followed by increased G2/M arrest and MMR-dependent apoptotic cell death. Moreover, FANCD2 knockout cells exhibited impaired CtIP and RAD51 recruitment to the damaged chromatin and DNA double-strand break accumulation, indicated by simultaneously observed increased γH2AX signal and 53BP1 foci.
CONCLUSIONS
Our data suggest that FANCD2 is crucial for recruiting homologous recombination factors to the sites of the MMR-dependent replication stress to resolve the arrested replication fork and counteract O-methylguanine-triggered MMR-dependent apoptosis.
Topics: Humans; DNA Mismatch Repair; Fanconi Anemia Complementation Group D2 Protein; Apoptosis; Guanine; HeLa Cells; DNA Damage; Methylnitrosourea; CRISPR-Cas Systems; Gene Knockout Techniques; Rad51 Recombinase; DNA Replication
PubMed: 38874758
DOI: 10.1007/s11033-024-09682-4 -
Food & Function Oct 2023In order to investigate the synergistic improving effect of lutein (LUT) and epigallocatechin-3-gallate (EGCG) treatment on retinitis pigmentosa (RP), an...
In order to investigate the synergistic improving effect of lutein (LUT) and epigallocatechin-3-gallate (EGCG) treatment on retinitis pigmentosa (RP), an -methyl--nitrosourea (MNU)-induced mouse model was conducted in the present study. Compared to the LUT alone treatment group, in the LUT combined with EGCG (LUT-EGCG) treatment group, the accumulation content of LUT was significantly increased by 50.24% in the liver. The morphological results indicated that LUT-EGCG treatment significantly improved the retina structure with the thickness of the outer nuclear layer restored to 185.28 ± 0.29 μm, showing no significant difference compared to the control group. The LUT-EGCG treatment also increased the production of short-chain fatty acids, such as acetic and propionic acids. Compared with the LUT alone treatment, the LUT-EGCG treatment significantly increased the relative abundance of and . RT-qPCR results indicated that LUT-EGCG treatment significantly increased the antiapoptotic gene Bcl-2 expression. In addition, the expression of IL-6 was significantly down-regulated in the LUT-EGCG group, while there was no significance in NF-κβ, TNF-α, IL-1β, and IL-18 compared with the LUT group. Correlation analysis supported the conclusion that LUT combined with EGCG may improve RP by modulating antiapoptotic gene expression and regulating the abundance of gut microbiota. However, the underlying mechanism still needs further research.
Topics: Mice; Animals; Methylnitrosourea; Lutein; Retinitis Pigmentosa; Retina; Catechin
PubMed: 37822286
DOI: 10.1039/d3fo02716c -
Biochemical and Biophysical Research... Sep 2024Generation of O-methylguanine (O-meG) by DNA-alkylating agents such as N-methyl N-nitrosourea (MNU) activates the multiprotein mismatch repair (MMR) complex and the...
Generation of O-methylguanine (O-meG) by DNA-alkylating agents such as N-methyl N-nitrosourea (MNU) activates the multiprotein mismatch repair (MMR) complex and the checkpoint response involving ATR/CHK1 and ATM/CHK2 kinases, which may in turn trigger cell cycle arrest and apoptosis. The Bloom syndrome DNA helicase BLM interacts with the MMR complex, suggesting functional relevance to repair and checkpoint responses. We observed a strong interaction of BLM with MMR proteins in HeLa cells upon treatment with MNU as evidenced by co-immunoprecipitation as well as colocalization in the nucleus as revealed by dual immunofluorescence staining. Knockout of BLM sensitized HeLa MR cells to MNU-induced cell cycle disruption and enhanced expression of the apoptosis markers cleaved caspase-9 and PARP1. MNU-treated BLM-deficient cells also exhibited a greater number of 53BP1 foci and greater phosphorylation levels of H2AX at S139 and RPA32 at S8, indicating the accumulation of DNA double-strand breaks. These findings suggest that BLM prevents double-strand DNA breaks during the MMR-dependent DNA damage response and mitigates O-meG-induced apoptosis.
Topics: Humans; RecQ Helicases; Apoptosis; DNA Mismatch Repair; HeLa Cells; DNA Breaks, Double-Stranded; Methylnitrosourea; Bloom Syndrome; Poly (ADP-Ribose) Polymerase-1
PubMed: 38850810
DOI: 10.1016/j.bbrc.2024.150214 -
International Journal of Biological... May 2024In this study, N-Methyl-N-nitrosourea (MNU) was intraperitoneally injected to construct a mouse retinitis pigmentosa (RP) model to evaluate the protective effect of...
In this study, N-Methyl-N-nitrosourea (MNU) was intraperitoneally injected to construct a mouse retinitis pigmentosa (RP) model to evaluate the protective effect of chitosan and β-carotene on RP. The results demonstrated that chitosan synergized with β-carotene significantly reduced retinal histopathological structural damage in RP mice. The co-treatment group of β-carotene and chitosan restored the retinal thickness and outer nuclear layer thickness better than the group treated with the two alone, and the thickness reached the normal level. The content of β-carotene and retinoids in the liver of chitosan and β-carotene co-treated group increased by 46.75 % and 20.69 %, respectively, compared to the β-carotene group. Chitosan and β-carotene supplement suppressed the expressions of Bax, Calpain2, Caspase3, NF-κB, TNF-α, IL-6, and IL-1β, and promoted the up-regulation of Bcl2. Chitosan and β-carotene interventions remarkably contributed to the content of SCFAs and enhanced the abundance of Ruminococcaceae, Rikenellaceae, Odoribacteraceae and Helicobacteraceae. Correlation analysis demonstrated a strong association between gut microbiota and improvement in retinitis pigmentosa. This study will provide a reference for the study of the gut-eye axis.
Topics: Animals; beta Carotene; Chitosan; Retinitis Pigmentosa; Mice; Methylnitrosourea; Drug Synergism; Retina; Disease Models, Animal; Gastrointestinal Microbiome; Male; Retinoids; Liver
PubMed: 38641272
DOI: 10.1016/j.ijbiomac.2024.131671 -
Cancer Science Jun 2024Rev1 has two important functions in the translesion synthesis pathway, including dCMP transferase activity, and acts as a scaffolding protein for other polymerases...
Rev1 has two important functions in the translesion synthesis pathway, including dCMP transferase activity, and acts as a scaffolding protein for other polymerases involved in translesion synthesis. However, the role of Rev1 in mutagenesis and tumorigenesis in vivo remains unclear. We previously generated Rev1-overexpressing (Rev1-Tg) mice and reported that they exhibited a significantly increased incidence of intestinal adenoma and thymic lymphoma (TL) after N-methyl-N-nitrosourea (MNU) treatment. In this study, we investigated mutagenesis of MNU-induced TL tumorigenesis in wild-type (WT) and Rev1-Tg mice using diverse approaches, including whole-exome sequencing (WES). In Rev1-Tg TLs, the mutation frequency was higher than that in WT TL in most cases. However, no difference in the number of nonsynonymous mutations in the Catalogue of Somatic Mutations in Cancer (COSMIC) genes was observed, and mutations involved in Notch1 and MAPK signaling were similarly detected in both TLs. Mutational signature analysis of WT and Rev1-Tg TLs revealed cosine similarity with COSMIC mutational SBS5 (aging-related) and SBS11 (alkylation-related). Interestingly, the total number of mutations, but not the genotypes of WT and Rev1-Tg, was positively correlated with the relative contribution of SBS5 in individual TLs, suggesting that genetic instability could be accelerated in Rev1-Tg TLs. Finally, we demonstrated that preleukemic cells could be detected earlier in Rev1-Tg mice than in WT mice, following MNU treatment. In conclusion, Rev1 overexpression accelerates mutagenesis and increases the incidence of MNU-induced TL by shortening the latency period, which may be associated with more frequent DNA damage-induced genetic instability.
Topics: Animals; Methylnitrosourea; Mice; Thymus Neoplasms; Mutagenesis; Nucleotidyltransferases; DNA-Directed DNA Polymerase; Mice, Transgenic; Lymphoma; Mutation; Exome Sequencing
PubMed: 38572512
DOI: 10.1111/cas.16159 -
International Journal of Molecular... Jan 2024Degenerative retinal diseases associated with photoreceptor loss are a leading cause of visual impairment worldwide, with limited treatment options. Phenotypic profiling...
Degenerative retinal diseases associated with photoreceptor loss are a leading cause of visual impairment worldwide, with limited treatment options. Phenotypic profiling coupled with medicinal chemistry were used to develop a small molecule with proliferative effects on retinal stem/progenitor cells, as assessed in vitro in a neurosphere assay and in vivo by measuring Msx1-positive ciliary body cell proliferation. The compound was identified as having kinase inhibitory activity and was subjected to cellular pathway analysis in non-retinal human primary cell systems. When tested in a disease-relevant murine model of adult retinal degeneration (MNU-induced retinal degeneration), we observed that four repeat intravitreal injections of the compound improved the thickness of the outer nuclear layer along with the regeneration of the visual function, as measured with ERG, visual acuity, and contrast sensitivity tests. This serves as a proof of concept for the use of a small molecule to promote endogenous regeneration in the eye.
Topics: Humans; Mice; Animals; Retinal Degeneration; Methylnitrosourea; Retina; Photoreceptor Cells; Regeneration; Disease Models, Animal; Mammals
PubMed: 38338800
DOI: 10.3390/ijms25031521 -
Scientific Reports Jan 2024Animal models for retinal degeneration are essential for elucidating its pathogenesis and developing new therapeutic strategies in humans. N-methyl-N-nitrosourea (MNU)...
Animal models for retinal degeneration are essential for elucidating its pathogenesis and developing new therapeutic strategies in humans. N-methyl-N-nitrosourea (MNU) has been extensively used to construct a photoreceptor-specific degeneration model, which has served to unveil the molecular process of photoreceptor degeneration as well as the mechanisms regulating the protective responses of remaining cells. Methyl methanesulphonate (MMS), also known to cause photoreceptor degeneration, is considered a good alternative to MNU due to its higher usability; however, detailed pathophysiological processes after MMS treatment remain uncharacterized. Here, we analyzed the time course of photoreceptor degeneration, Müller glial proliferation, and expression of secretory factors after MNU and MMS treatments in rats. While the timing of rod degeneration was similar between the treatments, we unexpectedly found that cones survived slightly longer after MMS treatment. Müller glia reentered the cell cycle at a similar timing after the two treatments; however, the G1/S transition occurred earlier after MMS treatment. Moreover, growth factors such as FGF2 and LIF were more highly upregulated in the MMS model. These data suggest that comparative analyses of the two injury models may be beneficial for understanding the complex regulatory mechanisms underlying the proliferative response of Müller glia.
Topics: Humans; Rats; Animals; Retinal Degeneration; Alkylating Agents; Neuroglia; Retinal Cone Photoreceptor Cells; Methylnitrosourea; Photoreceptor Cells, Vertebrate; Disease Models, Animal
PubMed: 38167441
DOI: 10.1038/s41598-023-50485-7 -
Biomedicine & Pharmacotherapy =... Jul 2024The incidence of breast cancer is increasing annually, making it a major health threat for women. Chemoprevention using natural, dietary, or synthetic products has...
The incidence of breast cancer is increasing annually, making it a major health threat for women. Chemoprevention using natural, dietary, or synthetic products has emerged as a promising approach to address this growing burden. Atractylenolide-III (AT-III), a sesquiterpenoid present in various medicinal herbs, has demonstrated potential therapeutic effects against several diseases, including tumors, nonalcoholic fatty liver disease, and cerebral ischemic injury. However, its impact on breast cancer chemoprevention remains unexplored. In this study, we used an N-methyl-N-nitrosourea (NMU)-induced rat breast cancer model and 17β-estradiol (E2)-treated MCF-10A cells to evaluate the chemopreventive potential of AT-III on mammary tumorigenesis. AT-III inhibited mammary tumor progression, evidenced by reduced tumor volume and multiplicity, prolonged tumor latency, and the reversal of NMU-induced weight loss. Furthermore, AT-III suppressed NMU-induced inflammation and oxidative stress through the Nrf2/ARE pathway in breast cancer tissues. In vitro, AT-III effectively suppressed E2-induced anchorage-independent growth and cell migration in MCF-10A cells. Nrf2 knockdown attenuated the protective effects of AT-III, highlighting the pivotal role of Nrf2 in AT-III-mediated suppression of tumorigenesis. The mechanism involves the induction of Nrf2 expression by AT-III through the autophagic degradation of Kelch-like ECH-associated protein 1 (Keap1). Overall, the results of this study indicate that AT-III is a promising candidate for breast cancer chemoprevention and provide valuable insights into its molecular interactions and signaling pathways.
Topics: Animals; NF-E2-Related Factor 2; Sesquiterpenes; Female; Kelch-Like ECH-Associated Protein 1; Lactones; Autophagy; Signal Transduction; Rats; Humans; Cell Line, Tumor; Rats, Sprague-Dawley; Mammary Neoplasms, Experimental; Oxidative Stress; Methylnitrosourea; Carcinogenesis; Anticarcinogenic Agents; Estradiol
PubMed: 38834007
DOI: 10.1016/j.biopha.2024.116852