Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025093
YY1 is a crucial transcription factor and plays significant roles in biological processes. However, the mechanisms of YY1 action in ischemia-reperfusion injury and its regulatory role in ferroptosis have not been extensively studied. This study aims to elucidate the molecular mechanism by which NEDD4L-mediated degradation of YY1 through ubiquitination suppresses SLC7A11 transcription, leading to the promotion of cellular ferroptosis and exacerbation of hepatic ischemia-reperfusion injury (IRI), via the integration of multiple omics sequencing datasets. An IRI-I/R mouse model is established, followed by proteomic sequencing to identify proteins that are differentially expressed during IRI. The altered expression of YY1 is validated, and in vivo and in vitro experiments are used to assess its impact on IRI damage. The E3 ligase NEDD4L, which regulates YY1 ubiquitination, is identified and validated via the UbiBrowser 2.0 database. The ubiquitination types of YY1 and its sites are screened and confirmed through in vitro experiments. Transcriptional sequencing of YY1-overexpressing cell lines is conducted to analyze the involvement of the downstream transcription factor SLC7A11 in IRI, followed by validation of its regulatory role. The results show that YY1 is downregulated in liver tissues during IRI and is expressed primarily in liver cells. YY1 overexpression alleviates liver tissue and liver cell IRI both in vitro and in vivo. Upregulation of E3 ligase expression during IRI promotes the K63-linked ubiquitination of YY1 at the K339 site, leading to proteasomal degradation of YY1. RNA-seq analysis and experimental validation demonstrate that YY1 suppresses IRI-induced ferroptosis via the transcriptional regulation of downstream target genes. YY1 positively regulates SLC7A11 transcription, inhibits IRI-induced ferroptosis and ameliorates liver injury. In summary, the E3 ubiquitin ligase NEDD4L facilitates YY1 protein degradation through ubiquitination, suppressing the transcription of the ferroptosis inhibitor SLC7A11, thus promoting IRI-related ferroptosis and exacerbating liver injury.
Acta Biochimica et Biophysica Sinica•2024•DOI: 10.3724/abbs.2024087
The aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) contribute to the development of neointima formation in vascular restenosis. This study aims to explore the function of the long noncoding RNA H19 in neointima formation. A mouse carotid ligation model was established, and human vascular smooth muscle cells (VSMCs) were used as a cell model. lncRNA H19 overexpression promoted VSMC proliferation and migration. Moreover, miR-125a-3p potentially bound to lncRNA H19, and Fms-like tyrosine kinase-1 (FLT1) might be a direct target of miR-125a-3p in VSMCs. Upregulation of miR-125a-3p alleviated lncRNA H19-enhanced VSMC proliferation and migration. Furthermore, rescue experiments showed that enhanced expression of miR-125a-3p attenuated lncRNA H19-induced FLT1 expression in VSMCs. In addition, the overexpression of lncRNA H19 significantly exacerbated neointima formation in a mouse carotid ligation model. In summary, lncRNA H19 stimulates VSMC proliferation and migration by acting as a competing endogenous RNA (ceRNA) of miR-125a-3p. lncRNA H19 may be a therapeutic target for restenosis.
Acta Biochimica et Biophysica Sinica•2024•DOI: 10.3724/abbs.2023287
Lung adenocarcinoma (LUAD) is one of the most aggressive types of lung cancer. The prognosis of LUAD patients remains poor, and the overall efficacy of gemcitabine-based chemotherapy is still unsatisfactory. Long noncoding RNAs (lncRNAs) play important roles in several cancer types by interacting with multiple proteins, RNA, and DNA. However, the relationship between lncRNA dysregulation and gemcitabine resistance in LUAD has not been fully elucidated. In this study, lncRNA CYTOR expression and its association with the prognosis of LUAD patients are assessed by quantitative RT-PCR and Kaplan-Meier survival analysis. In vitro and in vivo functional studies are conducted to evaluate the biological functions of CYTOR in LUAD. The underlying mechanism regarding the tumor-promoting effects of CYTOR is explored using RNA immunoprecipitation, biotin-labelled RNA pulldown, luciferase reporter assays, and western blot analysis. We identify that CYTOR is an oncogenic lncRNA and is apparently upregulated in LUAD by analysing TCGA-LUAD data. High CYTOR expression is a poor prognostic factor for LUAD. Functional studies reveal that CYTOR confers LUAD cells with stronger resistance to gemcitabine treatment and upregulates the expression levels of epithelial-mesenchymal transition (EMT)-related proteins. Mechanically, CYTOR acts as a competitive endogenous RNA (ceRNA) to absorb miR-125a-5p, weakens the antitumor function of miR-125a-5p, and ultimately upregulates ANLN and RRM2 expressions. Taken together, this study explains the mechanism of lncRNA in the gemcitabine resistance of LUAD and formulates a theoretical framework for the in depth study of LUAD.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025093
Hepatic ischemia-reperfusion injury (IRI) remains a major clinical challenge in liver transplantation and resection, with ferroptosis emerging as a critical cell death modality. This study investigates the mechanistic role of the transcription factor YY1 and its regulation by the E3 ubiquitin ligase NEDD4L in hepatic IRI. Using an established mouse IRI model and proteomic sequencing, YY1 was identified as significantly downregulated in injured liver tissues, predominantly in hepatocytes. In vivo and in vitro overexpression of YY1 attenuated IRI-induced liver damage and ferroptosis. Mechanistically, NEDD4L, an E3 ligase upregulated during IRI, was found to interact with YY1 and catalyze K63-linked ubiquitination at lysine 339, leading to proteasomal degradation of YY1. Transcriptomic analysis and validation revealed that YY1 positively regulates the transcription of SLC7A11, a key ferroptosis inhibitor. Consequently, NEDD4L-mediated degradation of YY1 suppresses SLC7A11 expression, promoting ferroptosis and exacerbating hepatic injury. These findings delineate a novel NEDD4L-YY1-SLC7A11 axis in IRI pathogenesis, offering potential therapeutic targets. The study acknowledges limitations, including the need for validation in human liver samples and further in vivo confirmation of some in vitro findings. This research provides a mechanistic framework for developing targeted interventions against hepatic IRI.