Yan Chen, Sarah E Bounds, Neloy Kundu, James Regun Karmoker, Yin Liu, Dongin Kim, Jiyang Cai
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This study aimed to identify potential molecular targets of miR-204 involved in microglia lipid processing and to determine whether RPE-derived EVs can improve the function of miR-204-deficient retinal microglia. <b>Methods:</b> Lipid accumulation in microglia was detected by staining with LipidTox, a fluorescent dye specific for neutral lipids, followed by either flow cytometry analysis or direct visualization on RPE/choroid flat mounts. MiRNA database and target prediction tools, such as miRWalk and TargetScan, were used to search for potential target genes of miR-204 in microglia. The identified target mRNA was validated with a miRNA reporter assay. RPE EVs were prepared from <i>ex vivo</i> cultured mice eye cups and administered via retro-orbital injection in miR-204 knockout (KO) mice. RPE integrity was assessed by ERG c-wave measurement. <b>Results:</b> KO of miR-204 resulted in the accumulation of neutral lipids in subretinal microglia. MiR-204 targeted the TGF-β receptor 2 gene in microglia. TGF-β markedly suppressed the expression of genes related to microglia lipid clearance. Eyes injected with RPE-derived EVs showed improved ERG c-wave responses compared to the fellow eyes injected with saline. <b>Conclusions:</b> This study supports that TGF-β/TGF-β receptor 2 regulates microglia lipid metabolism primarily by suppressing lipid clearance. By modulating TGF-β signaling, miR-204 in RPE-derived EVs likely enhances the lipid metabolic activities of subretinal microglia, which are crucial for the structural integrity and proper function of the outer retina and RPE. RPE-derived EVs and their delivery of miRNAs represent a potential therapeutic approach for treating retinal diseases, such as age-related macular degeneration, which involve dysregulated lipid metabolism in subretinal microglia.</p>","PeriodicalId":22932,"journal":{"name":"Theranostics","volume":"15 17","pages":"8952-8963"},"PeriodicalIF":13.3000,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12439270/pdf/","citationCount":"0","resultStr":"{\"title\":\"Role of MiR-204 in controlling metabolic functions of the subretinal microglia.\",\"authors\":\"Yan Chen, Sarah E Bounds, Neloy Kundu, James Regun Karmoker, Yin Liu, Dongin Kim, Jiyang Cai\",\"doi\":\"10.7150/thno.111807\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p><b>Rationale:</b> MicroRNA-204 (miR-204) is one of the most abundant miRNA species in the retinal pigment epithelium (RPE) and RPE-derived extracellular vesicles (EVs). Knockout (KO) of miR-204 leads to dysfunction and degeneration of both the RPE and the retina. In addition to previously reported retinal pathologies, we observed the accumulation of lipid-laden subretinal microglia in miR-204 KO mice. This study aimed to identify potential molecular targets of miR-204 involved in microglia lipid processing and to determine whether RPE-derived EVs can improve the function of miR-204-deficient retinal microglia. <b>Methods:</b> Lipid accumulation in microglia was detected by staining with LipidTox, a fluorescent dye specific for neutral lipids, followed by either flow cytometry analysis or direct visualization on RPE/choroid flat mounts. MiRNA database and target prediction tools, such as miRWalk and TargetScan, were used to search for potential target genes of miR-204 in microglia. The identified target mRNA was validated with a miRNA reporter assay. RPE EVs were prepared from <i>ex vivo</i> cultured mice eye cups and administered via retro-orbital injection in miR-204 knockout (KO) mice. RPE integrity was assessed by ERG c-wave measurement. <b>Results:</b> KO of miR-204 resulted in the accumulation of neutral lipids in subretinal microglia. MiR-204 targeted the TGF-β receptor 2 gene in microglia. TGF-β markedly suppressed the expression of genes related to microglia lipid clearance. Eyes injected with RPE-derived EVs showed improved ERG c-wave responses compared to the fellow eyes injected with saline. <b>Conclusions:</b> This study supports that TGF-β/TGF-β receptor 2 regulates microglia lipid metabolism primarily by suppressing lipid clearance. By modulating TGF-β signaling, miR-204 in RPE-derived EVs likely enhances the lipid metabolic activities of subretinal microglia, which are crucial for the structural integrity and proper function of the outer retina and RPE. RPE-derived EVs and their delivery of miRNAs represent a potential therapeutic approach for treating retinal diseases, such as age-related macular degeneration, which involve dysregulated lipid metabolism in subretinal microglia.</p>\",\"PeriodicalId\":22932,\"journal\":{\"name\":\"Theranostics\",\"volume\":\"15 17\",\"pages\":\"8952-8963\"},\"PeriodicalIF\":13.3000,\"publicationDate\":\"2025-08-11\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12439270/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Theranostics\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.7150/thno.111807\",\"RegionNum\":1,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2025/1/1 0:00:00\",\"PubModel\":\"eCollection\",\"JCR\":\"Q1\",\"JCRName\":\"MEDICINE, RESEARCH & EXPERIMENTAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Theranostics","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.7150/thno.111807","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/1/1 0:00:00","PubModel":"eCollection","JCR":"Q1","JCRName":"MEDICINE, RESEARCH & EXPERIMENTAL","Score":null,"Total":0}
Role of MiR-204 in controlling metabolic functions of the subretinal microglia.
Rationale: MicroRNA-204 (miR-204) is one of the most abundant miRNA species in the retinal pigment epithelium (RPE) and RPE-derived extracellular vesicles (EVs). Knockout (KO) of miR-204 leads to dysfunction and degeneration of both the RPE and the retina. In addition to previously reported retinal pathologies, we observed the accumulation of lipid-laden subretinal microglia in miR-204 KO mice. This study aimed to identify potential molecular targets of miR-204 involved in microglia lipid processing and to determine whether RPE-derived EVs can improve the function of miR-204-deficient retinal microglia. Methods: Lipid accumulation in microglia was detected by staining with LipidTox, a fluorescent dye specific for neutral lipids, followed by either flow cytometry analysis or direct visualization on RPE/choroid flat mounts. MiRNA database and target prediction tools, such as miRWalk and TargetScan, were used to search for potential target genes of miR-204 in microglia. The identified target mRNA was validated with a miRNA reporter assay. RPE EVs were prepared from ex vivo cultured mice eye cups and administered via retro-orbital injection in miR-204 knockout (KO) mice. RPE integrity was assessed by ERG c-wave measurement. Results: KO of miR-204 resulted in the accumulation of neutral lipids in subretinal microglia. MiR-204 targeted the TGF-β receptor 2 gene in microglia. TGF-β markedly suppressed the expression of genes related to microglia lipid clearance. Eyes injected with RPE-derived EVs showed improved ERG c-wave responses compared to the fellow eyes injected with saline. Conclusions: This study supports that TGF-β/TGF-β receptor 2 regulates microglia lipid metabolism primarily by suppressing lipid clearance. By modulating TGF-β signaling, miR-204 in RPE-derived EVs likely enhances the lipid metabolic activities of subretinal microglia, which are crucial for the structural integrity and proper function of the outer retina and RPE. RPE-derived EVs and their delivery of miRNAs represent a potential therapeutic approach for treating retinal diseases, such as age-related macular degeneration, which involve dysregulated lipid metabolism in subretinal microglia.
期刊介绍：
Theranostics serves as a pivotal platform for the exchange of clinical and scientific insights within the diagnostic and therapeutic molecular and nanomedicine community, along with allied professions engaged in integrating molecular imaging and therapy. As a multidisciplinary journal, Theranostics showcases innovative research articles spanning fields such as in vitro diagnostics and prognostics, in vivo molecular imaging, molecular therapeutics, image-guided therapy, biosensor technology, nanobiosensors, bioelectronics, system biology, translational medicine, point-of-care applications, and personalized medicine. Encouraging a broad spectrum of biomedical research with potential theranostic applications, the journal rigorously peer-reviews primary research, alongside publishing reviews, news, and commentary that aim to bridge the gap between the laboratory, clinic, and biotechnology industries.
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