Histone demethylase JMJD3 downregulation protects against aberrant force-induced osteoarthritis through epigenetic control of NR4A1 / 国际口腔科学杂志·英文版

Osteoarthritis (OA) is a prevalent joint disease with no effective treatment strategies. Aberrant mechanical stimuli was demonstrated to be an essential factor for OA pathogenesis. Although multiple studies have detected potential regulatory mechanisms underlying OA and have concentrated on developing novel treatment strategies, the epigenetic control of OA remains unclear. Histone demethylase JMJD3 has been reported to mediate multiple physiological and pathological processes, including cell differentiation, proliferation, autophagy, and apoptosis. However, the regulation of JMJD3 in aberrant force-related OA and its mediatory effect on disease progression are still unknown. In this work, we confirmed the upregulation of JMJD3 in aberrant force-induced cartilage injury in vitro and in vivo. Functionally, inhibition of JMJD3 by its inhibitor, GSK-J4, or downregulation of JMJD3 by adenovirus infection of sh-JMJD3 could alleviate the aberrant force-induced chondrocyte injury. Mechanistic investigation illustrated that aberrant force induces JMJD3 expression and then demethylates H3K27me3 at the NR4A1 promoter to promote its expression. Further experiments indicated that NR4A1 can regulate chondrocyte apoptosis, cartilage degeneration, extracellular matrix degradation, and inflammatory responses. In vivo, anterior cruciate ligament transection (ACLT) was performed to construct an OA model, and the therapeutic effect of GSK-J4 was validated. More importantly, we adopted a peptide-siRNA nanoplatform to deliver si-JMJD3 into articular cartilage, and the severity of joint degeneration was remarkably mitigated. Taken together, our findings demonstrated that JMJD3 is flow-responsive and epigenetically regulates OA progression. Our work provides evidences for JMJD3 inhibition as an innovative epigenetic therapy approach for joint diseases by utilizing p5RHH-siRNA nanocomplexes.

SPDEF suppresses head and neck squamous cell carcinoma progression by transcriptionally activating NR4A1 / 国际口腔科学杂志·英文版

SAM pointed domain containing E26 transformation-specific transcription factor (SPDEF) plays dual roles in the initiation and development of human malignancies. However, the biological role of SPDEF in head and neck squamous cell carcinoma (HNSCC) remains unclear. In this study, the expression level of SPDEF and its correlation with the clinical parameters of patients with HNSCC were determined using TCGA-HNSC, GSE65858, and our own clinical cohorts. CCK8, colony formation, cell cycle analysis, and a xenograft tumor growth model were used to determine the molecular functions of SPDEF in HNSCC. ChIP-qPCR, dual luciferase reporter assay, and rescue experiments were conducted to explore the potential molecular mechanism of SPDEF in HNSCC. Compared with normal epithelial tissues, SPDEF was significantly downregulated in HNSCC tissues. Patients with HNSCC with low SPDEF mRNA levels exhibited poor clinical outcomes. Restoring SPDEF inhibited HNSCC cell viability and colony formation and induced G0/G1 cell cycle arrest, while silencing SPDEF promoted cell proliferation in vitro. The xenograft tumor growth model showed that tumors with SPDEF overexpression had slower growth rates, smaller volumes, and lower weights. SPDEF could directly bind to the promoter region of NR4A1 and promoted its transcription, inducing the suppression of AKT, MAPK, and NF-κB signaling pathways. Moreover, silencing NR4A1 blocked the suppressive effect of SPDEF in HNSCC cells. Here, we demonstrate that SPDEF acts as a tumor suppressor by transcriptionally activating NR4A1 in HNSCC. Our findings provide novel insights into the molecular mechanism of SPDEF in tumorigenesis and a novel potential therapeutic target for HNSCC.

Early use of dexamethasone increases Nr4a1 in Kupffer cells ameliorating acute liver failure in mice in a glucocorticoid receptor-dependent manner / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

BACKGROUND AND OBJECTIVE@#Acute liver failure (ALF) is a type of disease with high mortality and rapid progression with no specific treatment methods currently available. Glucocorticoids exert beneficial clinical effects on therapy for ALF. However, the mechanism of this effect remains unclear and when to use glucocorticoids in patients with ALF is difficult to determine. The purpose of this study was to investigate the specific immunological mechanism of dexamethasone (Dex) on treatment of ALF induced by lipopolysaccharide (LPS)/D-galactosamine (D-GaIN) in mice.@*METHODS@#Male C57BL/6 mice were given LPS and D-GaIN by intraperitoneal injection to establish an animal model of ALF. Dex was administrated to these mice and its therapeutic effect was observed. Hematoxylin and eosin (H&E) staining was used to determine liver pathology. Multicolor flow cytometry, cytometric bead array (CBA) method, and next-generation sequencing were performed to detect changes of messenger RNA (mRNA) in immune cells, cytokines, and Kupffer cells, respectively.@*RESULTS@#A mouse model of ALF can be constructed successfully using LPS/D-GaIN, which causes a cytokine storm in early disease progression. Innate immune cells change markedly with progression of liver failure. Earlier use of Dex, at 0 h rather than 1 h, could significantly improve the progression of ALF induced by LPS/D-GaIN in mice. Numbers of innate immune cells, especially Kupffer cells and neutrophils, increased significantly in the Dex-treated group. In vivo experiments indicated that the therapeutic effect of Dex is exerted mainly via the glucocorticoid receptor (Gr). Sequencing of Kupffer cells revealed that Dex could increase mRNA transcription level of nuclear receptor subfamily 4 group A member 1 (Nr4a1), and that this effect disappeared after Gr inhibition.@*CONCLUSIONS@#In LPS/D-GaIN-induced ALF mice, early administration of Dex improved ALF by increasing the numbers of innate immune cells, especially Kupffer cells and neutrophils. Gr-dependent Nr4a1 upregulation in Kupffer cells may be an important ALF effect regulated by Dex in this process.

NSC-640358 acts as RXRα ligand to promote TNFα-mediated apoptosis of cancer cell

Retinoid X receptor α (RXRα) and its N-terminally truncated version tRXRα play important roles in tumorigenesis, while some RXRα ligands possess potent anti-cancer activities by targeting and modulating the tumorigenic effects of RXRα and tRXRα. Here we describe NSC-640358 (N-6), a thiazolyl-pyrazole derived compound, acts as a selective RXRα ligand to promote TNFα-mediated apoptosis of cancer cell. N-6 binds to RXRα and inhibits the transactivation of RXRα homodimer and RXRα/TR3 heterodimer. Using mutational analysis and computational study, we determine that Arg316 in RXRα, essential for 9-cis-retinoic acid binding and activating RXRα transactivation, is not required for antagonist effects of N-6, whereas Trp305 and Phe313 are crucial for N-6 binding to RXRα by forming extra π-π stacking interactions with N-6, indicating a distinct RXRα binding mode of N-6. N-6 inhibits TR3-stimulated transactivation of Gal4-DBD-RXRα-LBD by binding to the ligand binding pocket of RXRα-LBD, suggesting a strategy to regulate TR3 activity indirectly by using small molecules to target its interacting partner RXRα. For its physiological activities, we show that N-6 strongly inhibits tumor necrosis factor α (TNFα)-induced AKT activation and stimulates TNFα-mediated apoptosis in cancer cells in an RXRα/tRXRα dependent manner. The inhibition of TNFα-induced tRXRα/p85α complex formation by N-6 implies that N-6 targets tRXRα to inhibit TNFα-induced AKT activation and to induce cancer cell apoptosis. Together, our data illustrate a new RXRα ligand with a unique RXRα binding mode and the abilities to regulate TR3 activity indirectly and to induce TNFα-mediated cancer cell apoptosis by targeting RXRα/tRXRα.

Expression and purification of DNA binding domain of NR4A1 / 中南大学学报(医学版)

OBJECTIVE@#To express and purify NR4A1-DNA binding domain (DBD) protein of nuclear receptors.@*METHODS@#The fusion protein PET28a-NR4A1-DBD was constructed and purified with the nickel affinity chromatography, cation-exchange chromatography and gel filtration chromatography.@*RESULTS@#The protein PET28a-NR4A1-DBD was mostly soluable at 24 °C. A total of 2-3 mg/L pure NR4A1 proteins were yielded in bacterial culture and the purity for final fractions of NR4A1-DBD protein were great than 95% by SDS-PAGE analysis.@*CONCLUSION@#Nickel affinity chromatography is effective to purify protein. The protein purity can be further improved by the following methods including cation-exchange chromatography and gel filtration chromatography.

Changes of NGFI-B subcellular location in cardiomyocytes of stressed rats and its biological effects / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the changes of expression and subcellular location of nuclear growth-induced protein-B(NGFI-B) in cardiomyocytes of stressed rats and its biological effect and to provide scientific evidences for exploring the mechanism underlying myocardium injury induced by stress.</p><p><b>METHODS</b>The cell model of stress-induced cardiomyocyte injury were established. Western blot method and confocal microscopy method were used to investigate the subcellular location of NGFI-B in cardiomyocytes under stress. The flow-cytometry was selected to detect the apoptotic rate in cardiomyocytes in vitro. Western blot method was used to determine the content of cytochrome C protein in mitochondria and cytoplasm respectively.</p><p><b>RESULTS</b>Stress induced the increase of NGFI-B content in the mitochondria of cardiomyocytes and the translocation of NGFI-B from the nucleus to the mitochondria. The translocation of NGFI-B promoted the release of cytochrome C from the mitochondria and the cardiomyocyte apoptosis. Treatment of stressed cardiomyocytes with leptomycin B, a non-specific blocker of nuclear export, resulted in nuclear retention of NGFI-B and abrogated its ability to induce the release of cytochrome C from the mitochondria.</p><p><b>CONCLUSION</b>Stress could induce NGFI-B translocation from the nucleus to the mitochondria in cardiomyocytes, which activated the mitochondrial pathway of cell apoptosis.</p>

The assay of transcriptional activation effect of TR3 and deletion mutation in the yeast two hybrid system / 中国应用生理学杂志

<p><b>AIM</b>To assay the transcriptional activation effect of TR3 and it's deletion mutation in yeast two hybrid system.</p><p><b>METHODS</b>The total length of TR3 and TR3/delta1-690 gene was amplified by PCR method and cloned into pGBKT7 vector. Bait vector of pGBKT7-TR3 and pGBKT7-TR3/delta1-690 was transformed into AH109 competence yeast. Then self activation of the recombination vector was tested by assay the activity of beta-galactosidae.</p><p><b>RESULTS</b>The pGBKT7-TR3 and pGBKT7-TR3/AM 690 vector was successfully constructed. The filter paper containing beta-galactosidae didn't changed to blue showed that the reporter gene wasn't activationed.</p><p><b>CONCLUSION</b>TR3 and TR3/delta1-690 hadn't the activity of transcriptional activation.</p>

Nuclear receptor Nur77 inhibits oxidized low density lipoprotein induced lipid loading in macrophages / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the effect of Nur77 on lipid loading in macrophages exposed to 40 microg/ml oxidized low density lipoprotein (ox-LDL).</p><p><b>METHODS</b>Stable RAW264.7 strain expressing green fluorescent protein (GFP) or GFP-Nur77 was established by G418 screening after transfection with corresponding plasmids and identified by Western blot. After 24 h stimulation with ox-LDL, intracellular lipid loading of each strain was observed by Oil Red O dyeing, and the intracellular cholesterol level was measured by liquid chromatographic-mass spectrometry (LC-MS). The transcriptional changes of CD36 and ABCA1 were monitored by Real Time Quantitative-PCR, while the expressions of these two proteins were assayed by flow cytometry and Western blot, respectively.</p><p><b>RESULTS</b>After 24 h stimulation with ox-LDL, intracellular total cholesterol and esterified cholesterol concentration in GFP-Nur77-RAW264.7 were significantly dropped by 26.15% and 30.93% respectively (P < 0.05 vs. GFP-RAW264.7). The transcription and expression of ABCA1 in GFP-Nur77-RAW264.7 were significantly increased while the transcription and expression of CD36 were significantly reduced (all P < 0.05 vs. GFP-RAW264.7).</p><p><b>CONCLUSION</b>Orphan nuclear receptor Nur77 reduced ox-LDL induced intracellular lipid loading in macrophages by inhibiting lipid influx and enhancing lipid efflux.</p>