SIRT1 is transcriptionally repressed by YY1 and suppresses ferroptosis in rheumatoid arthritis

Abstract Background Sirtuin 1 (SIRT1) is reported downregulated in rheumatoid arthritis (RA), and the protective effects of SIRT1 on tissue damage and organ failure may be related to cellular ferroptosis. However, the exact mechanism by which SIRT1 regulates RA remains unclear. Methods Quantitative real-time PCR (qPCR) and western blot assays were performed to explore the expressions of SIRT1 and Yin Yang 1 (YY1). CCK-8 assay was used for cytoactive detection. The interaction between SIRT1 and YY1 was validated by dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP). DCFH-DA assay and iron assay were applied to detect the reactive oxygen species (ROS) and iron ion levels. Results In the serum of RA patients, SIRT1 was downregulated, but YY1 was upregulated. In LPS-induced synoviocytes, SIRT1 could increase cell viability and decrease ROS and iron levels. Mechanistically, YY1 downregulated the expression of SIRT1 by inhibiting its transcription. YY1 overexpression partly revised the effects of SIRT1 on ferroptosis in synoviocytes. Conclusion SIRT1 is transcriptionally repressed by YY1 and inhibits the ferroptosis of synoviocytes induced by LPS, so as to relieve the pathological process of RA. Therefore, SIRT1 might be a new diagnosis and therapeutic target of RA. Highlights Combining SIRT1 with synoviocytes ferroptosis in rheumatoid arthritis for the first time. The transcription factor YY1 combined to the SIRT1 promoter in synovial cells and inhibited its expression and functional roles. The inhibition of SIRT1 with YY1 decreased the ferroptosis in synoviocytes.

The nucleocapsid protein of rice stripe virus in cell nuclei of vector insect regulates viral replication

Rice stripe virus (RSV) transmitted by the small brown planthopper causes severe rice yield losses in Asian countries. Although viral nuclear entry promotes viral replication in host cells, whether this phenomenon occurs in vector cells remains unknown. Therefore, in this study, we systematically evaluated the presence and roles of RSV in the nuclei of vector insect cells. We observed that the nucleocapsid protein (NP) and viral genomic RNAs were partially transported into vector cell nuclei by utilizing the importin α nuclear transport system. When blocking NP nuclear localization, cytoplasmic RSV accumulation significantly increased. In the vector cell nuclei, NP bound the transcription factor YY1 and affected its positive regulation to FAIM. Subsequently, decreased FAIM expression triggered an antiviral caspase-dependent apoptotic reaction. Our results reveal that viral nuclear entry induces completely different immune effects in vector and host cells, providing new insights into the balance between viral load and the immunity pressure in vector insects.

YY1 induced hypoxic breast cancer-derived exosomal circ_000543 promotes proliferation and invasion of breast cancer cells / 中华内分泌外科杂志

Objective:To investigate the effects of circ_000543 derived from hypoxic exosomes on proliferation and invasion of breast cancer (BC) cells.Methods:Bioinformatic website was used to predict the abnormal expression of circ_000543 in BC tissue and the transcription factor that might regulate circ_000543. Double luciferase report experiment and ChIP assay were used to confirm the regulation relationship between YY1 and circ_000543. Exosomes were separated from normal BC cells and BC cells under hypoxic condition, and qRT-PCR was adopted to detect the expression of circ_000543 in exosomes. The expression of circ_000543 and YY1 in exosomes was intervened and the exosomes were cocultured with BC cells under normoxia. CCK8 and Transwell assay was used to detect the proliferation and invasive ability individually.Results:qRT-PCR experiment found that, compared with MCF-10A cells (1±0.11) and exosomes isolated from normoxic cells (1±0.10), circ_000543 expression was up-regulated in BC cells (1.59±0.13) and exosomes derived from cells under hypoxic condition (1.63±0.12) ( t=6.001, P=0.004; t=6.986, P=0.002). Exosomes derived from cells under hypoxic condition promoted proliferation and invasion of BC cells under normoxia. Inhibition of circ_000543 partially offset the effects of exosomes. YY1 induced the expression of circ_000543 in BC cells as a transcription factor. The expression of circ_000543 was inhibited when YY1 expression was down-regulated; at the same time, down-regulation of YY1 inhibited the effects of exosomes on proliferation and invasion of BC cells. Conclusion:The transcription factor YY1 promoted proliferation and invasion of BC cells by inducing hypoxic breast cancer-derived exosomal circ_000543.

Yin-Yang-1 decreases Fas-induced apoptosis in acute lymphoblastic leukemia under hypoxic conditions: its implications in immune evasion / YY1 induce la disminución de la apoptosis a través de Fas en la leucemia linfoblástica aguda en condiciones hipóxicas: implicaciones en la evasión de la respuesta inmunitaria

Abstract Background: Acute lymphoblastic leukemia (ALL) is an aggressive malignant disease with high prevalence in pediatric patients. It has been shown that the downregulation of Fas expression is correlated with an inadequate response in ALL, although these mechanisms are still not well understood. Several reports demonstrated that hypoxia is involved in dysfunctional apoptosis. Yin-Yang-1 (YY1) transcription factor is involved in resistance to apoptosis, tumor progression, and it is increased in different types of cancer, including leukemia. The regulatory mechanism underlying YY1 expression in leukemia is still not understood, but it is known that YY1 negatively regulates Fas expression. The study aimed to evaluate the effect of YY1 on Fas expression under hypoxic conditions in ALL. Methods: Leukemia cell line RS4; 11 was cultured under normoxic and hypoxic conditions. YY1, Fas receptor, and hypoxia-inducible factor (HIF-1α) expression were analyzed. After treatment with a Fas agonist (DX2), apoptosis was analyzed through the detection of active caspase 3. Data were analyzed using Pearson’s correlation. Results: Leukemia cells co-expressed both HIF-1α and YY1 under hypoxia, which correlated with a downregulation of Fas expression. During hypoxia, the levels of apoptosis diminished after DX2 treatment. The analysis revealed that patients with high levels of HIF-1α also express high levels of YY1 and low levels of Fas. Conclusions: These results suggest that YY1 negatively regulates the expression of the Fas receptor, which could be involved in the escape of leukemic cells from the immune response contributing to the ALL pathogenesis.

Resumen Introducción: La leucemia linfoblástica aguda (LLA) es una enfermedad con alta prevalencia en la población pediátrica. El mecanismo por el cual el receptor de Fas participa en la regulación inmunitaria en los tumores es desconocido, pero se sabe que está subexpresado en LLA. El factor de transcripción Ying-Yang-1 (YY1) está involucrado en la resistencia a la apoptosis y la progresión tumoral; se encuentra aumentado en diferentes tumores, incluida la LLA. Aunque los mecanismos que regulan la expresión de YY1 en LLA son desconocidos, se sabe que YY1 regula la expresión del receptor de Fas. El objetivo de este trabajo fue evaluar el efecto de YY1 en la expresión de Fas en condiciones de hipoxia en la LLA. Métodos: Se cultivaron células RS4;11 en condiciones de hipoxia y se analizó la expresión de YY1, receptor de Fas y HIF-1α. La apoptosis fue inducida usando un agonista de Fas (DX2) y se analizó con la detección de caspasa 3 activa. Los datos se analizaron mediante correlación de Pearson. Resultados: Las células RS4;11 coexpresaron HIF-1αy YY1 en hipoxia, lo cual correlaciona con una baja expresión de Fas. La apoptosis se encontró disminuida durante condiciones de hipoxia, después del tratamiento con DX2. El análisis bioinformático mostró que los pacientes con altos niveles de HIF-1αpresentan YY1 elevado y bajos niveles del receptor de Fas. Conclusiones: Estos resultados sugieren que YY1 regula negativamente la expresión del receptor de Fas, lo cual podría estar involucrado en el escape de las células leucémicas a la respuesta inmunitaria, contribuyendo a la patogénesis de la LLA.

Differentiation of HaCaT cells infected with lentivirus / 中国组织工程研究

BACKGROUND:YY1 is mainly expressed in the undifferentiated epidermic cells in mouse basal lamina, and the expression level is gradual y down-regulated as the differentiation towards suprabasal lamina. The differential expression indicates that, YY1 is one of the regulators in the process of epidermic cells differentiation. OBJECTIVE:To observe the effects of YY1 over-expression on the differentiation of HaCaT cells infected with lentivirus. METHODS:Lentivirus-YY1 was transferred into the HaCaT cells by using Lipofectamine 2000. After selection of the puromycin, monoclonal celllines were established, and the control group were lentivirus-infected HaCaT cells and uninfected HaCaT cells. The expression of YY1 was detected by using western blot analysis. cells in Lentivirus-YY1-HaCaT group and HaCaT-YY1 group were further divided into two subgroups according to the calcium concentration in culture medium, cells were either cultured in low-calcium medium (0.12 mmol/L) for 48 hours, or cultured in low-calcium medium (0.12 mmol/L) for 24 hours and in high-calcium medium (0.35 mmol/L) for additional 24 hours. Keratin K1, K10, K14, and involucrin, filaggrin and loricrin after over-expression of YY1 were detected with western blot analysis. RESULTS AND CONCLUSION:The HaCaT cells were successful y infected with lentivirus-YY1, and we obtained over-expression of YY1 protein in monoclonal celllines under high-calcium concentrations, the over-expressed YY1 could decrease the expression of K1, involucrin and loricrin, thereby preventing the process of epidermal keratinocytes and maintaining the cells in an undifferentiated state. Lentivirus can efficiently infect human immortalized epidermal cellHaCaT, and YY1 may the important factor of inhibiting the differentiation of basal epidermal cells and maintaining the undifferentiated proliferation status.

Regulation and Function of the Peg3 Imprinted Domain

A subset of mammalian genes differ functionally between two alleles due to genomic imprinting, and seven such genes (Peg3, Usp29, APeg3, Zfp264, Zim1, Zim2, Zim3) are localized within the 500-kb genomic interval of the human and mouse genomes, constituting the Peg3 imprinted domain. This Peg3 domain shares several features with the other imprinted domains, including an evolutionarily conserved domain structure, along with transcriptional co-regulation through shared cis regulatory elements, as well as functional roles in controlling fetal growth rates and maternal-caring behaviors. The Peg3 domain also displays some unique features, including YY1-mediated regulation of transcription and imprinting; conversion and adaptation of several protein-coding members as ncRNA genes during evolution; and its close connection to human cancers through the potential tumor suppressor functions of Peg3 and Usp29. In this review, we summarize and discuss these features of the Peg3 domain.

Transcription factor Yin-Yang1 and tumor / 国际肿瘤学杂志

Yin-Yang1 (YY1),as a ubiquitous nuclear transcription factor with double transcriptional activity in eukaryotic cells,regulates many genes transcription and plays an important role in the cellule biological processes.Overexpression of YY1 is found in several tumor types recently,and may play a role in tumor development and progression by regulating oncogenes,tumor suppressor genes,angiogenesis related factors,as well as apoptosis.YY1 may become a new kind of tumor markers,is conducive to estimate the prognosis of patients with tumor and gain important breakthrough in cancer targeted therapy.

Evaluación de la expresión del factor de transcripción Yin-Yang-1 y su asociación con TGF-β en un modelo murino de inflamación alérgica pulmonar con diferentes grados de severidad / Evaluation of the expression of the transcription factor Yin-Yang-1: association with TGF-β in a lung allergic inflammation in a mouse model with different severity grades

Introducción. El asma alérgica es una de las enfermedades más prevalecientes en la edad pediátrica. Los mecanismos implicados en este padecimiento no han sido esclarecidos totalmente. Se sabe que el factor de crecimiento transformante-beta (TGF-β) juega un papel muy importante en la fisiopatología de esta enfermedad y que la activación del factor de trascripción Yin-Yang-1 (YY1) induce un aumento en la expresión de esta citocina. El factor YY1 también regula la expresión de otras citocinas involucradas en el asma tales como la IL-4 y la IL-10. El objetivo de este trabajo fue evaluarla asociación entre YY1 y TGF-β en un modelo murino de inflamación alérgica pulmonar. Métodos. Se trabajó con un modelo murino de inflamación alérgica pulmonar con diferentes grados de severidad empleando ovalbúmina como alérgeno. Posteriormente se obtuvo el tejido pulmonar, que fue incluido en parafina, se construyó un microarreglo del tejido en un equipo semiautomático y, mediante inmunohistoquímica, se evaluó la expresión de YY1 y de TGF-β La densidad de la expresión se midió de manera cuantitativa por métodos computarizados. Resultados. Se observó inflamación alérgica pulmonar diferencial acorde con el grado de severidad del modelo; se observó el mismo patrón con la producción de moco. La expresión de ambas proteínas se correlacionó de manera directa con el grado de severidad de la inflamación alérgica pulmonar. Conclusiones. Los resultados obtenidos corroboran el papel que juegan ambas proteínas en la fisiopatología de la inflamación alérgica pulmonar.

Background. Allergic asthma is one of the most prevalent childhood diseases. This disease is characterized by airway inflammation and remodelling. The mechanisms implicated in the pathogenesis of this disease remain unclear. Several studies have shown that TGF-β plays an important role in the pathogenesis of asthma. In addition, the polymorphism of the TGF-β promoter region results in the overexpression of TGF-β via regulation of the transcription factor Yin-Yang-1 (YY1). It is has recently been demonstrated that YY1 may be involved in the pathogenesis of asthma by the regulation of IL-4 and IL-10. The aim of this study was to evaluate the association between the YY1 and TGF-β expression levels in a murine model of lung allergic inflammation. Methods. In this study we used a lung allergic inflammatory murine model with different severity degrees. Tissue microarray technology and immunohistochemistry were used to evaluate YY1 and TGF-p expression. The density expression was measured by quantitative methods using specific software. Results. Expression of both proteins correlated with the degrees of severity of lung allergic inflammation. A similar result was observed with mucus production. Conclusions. These results corroborate the role of YY1 and TGF-p in the pathogenesis of this disease.

Weakening of the repressive YY-1 site on the thrombospondin-1 promoter via c-Jun/YY-1 interaction

Thrombospondin-1 (TSP-1) level is tightly regulated at the transcriptional level. To determine the detailed molecular mechanisms of TSP-1 expression, nine serial 5'-deletion constructs of the human genomic tsp-1 promoter (nucleotides -2,220 to +756) were prepared, inserted into luciferase reporter plasmids, and transiently transfected into the Hep3B human hepatocarcinoma cell. Among the nine 5'-deletion constructs, pTSP-Luc-4 (-767~+756) had consistently decreased luciferase activity with or without PMA stimulation, whereas a further truncated construct [pTSP-Luc-4' (-407~+756)] had increased levels of expression. By searching the nucleotides from -767 to -407, a consensus binding sequence (5'-CCATTTT-3') for the repressor Yin Yang-1 (YY-1) at nucleotide -440 was identified. The suppression induced by this site was weakened in the presence of the region upstream of nucleotide -767 (pTSP-Luc-1 and -2). Nuclear protein directly bound to an oligonucleotide containing the repressive YY-1 sequence but the binding capacity of the sequence was decreased by the increased c-Jun levels. Moreover, proteins immunoprecipitated with anti-YY-1 revealed an interaction between c-Jun and YY-1 factor. These data suggest that the repressive YY-1 site of the tsp-1 promoter could not be functional via activating positive cis-elements on the upstream from this site and weakened via c-Jun/YY-1 interactions.

Increased transcriptional activity by mutation of HPV-16URR in cervical cancers carrying episomal HPV-16 DNA / 대한부인종양콜포스코피학회잡지

HPV E2 protein is known to act as a negative regulator of transcription and the disruption of E2 open reading frame by HPV integration can release suppression of E6 and E7 mRNA expression, resulting in uncontrolled cellular growth and malignant transformation by inactivating tumor suppressor gene products (p53, pRb). YY1 mutation of HPV URR has been suggested as one of indicator that explains development of cervical neoplasia by episomal type of HPV. To extend this hypothesis, we examined whether mutation(s) in specific sites of HPV URR is functionally related to the invasiveness of cervical neoplasia and the physical status of HPV DNA. The URR sequences were obtained by PCR amplification of HPV-16 genome from CIN and invasive cancer patients, cloned into pUC18 for sequencing, and into pBLCAT8+ for functional CAT assay. Our previous data classified HPV-infected patients into three groups: 3 cancer cases carrying episomal HPV DNA; 12 cancer cases carrying integrated HPV DNA; 12 CIN cases carrying episomal HPV DNA. The specific variants in HPV-16 URR were found in Korean women: GA transition at nt 7520 (100%, 27/27), AC transition at nt 7729 (70%; 19/27), and GA transition at nt 7841 (78%; 21/27). Selective mutations were observed at the YY1-binding sites of HPV-16 URR in the 3 patients with invasive cervical cancer, who having the episomal forms of HPV-16 DNA: AC transition at nt 7484 and GA transition at nt 7488 (YY1-binding site 2; from 7481 to 7489). Additionally, CT transition at nt 7785 (YY1-binding site 3; from 7781 to 7790) was found from 2 of 3 patients. No YY1 site mutations were detected in the 12 CIN patients and in the HPV-integrated invasive cancer patients. To determine whether these mutations have effect on the expression of HPV E6/E7 genes driven by URR, the transient transfection assay was employed using URR-CAT reporter plasmid. The relative activities of three URR mutants from episomal HPV-16 DNA of cervical cancers were 2- to 4-fold higher than that of HPV-16 URR prototype. In contrast, the URRs from integrated HPV-16 DNA in cervical cancer and from episomal HPV-16 DNA in CIN, where no mutation of the YY1-binding site was detected, showed similar levels of promoter activity to that of URR prototype.Our results support the hypothesis that the mutation at YY1 binding site is functionally related to the development of cervical neoplasia caused by episomal HPV-16 DNA in Korean cervical cancer patient. Thus, mutation in YY1 site of episomal HPV-16 URR may play a role of HPV integration in the progression of cervical cancer.