ABSTRACT
Microglial activation occurs in divergent neuropathological conditions. Such microglial event has the key involvement in the progression of CNS diseases. However, the transcriptional mechanism governing microglial activation remains poorly understood. Here, we investigate the microglial response to traumatic injury-induced neurodegeneration by the 3D fluorescence imaging technique. We show that transcription factors IRF8 and PU.1 are both indispensible for microglial activation, as their specific post-developmental deletion in microglia abolishes the process. Mechanistically, we reveal that IRF8 and PU.1 directly target the gene transcription of each other in a positive feedback to sustain their highly enhanced expression during microglial activation. Moreover, IRF8 and PU.1 dictate the microglial response by cooperatively acting through the composite IRF-ETS motifs that are specifically enriched on microglial activation-related genes. This action of cooperative transcription can be further verified biochemically by the synergetic binding of IRF8 and PU.1 proteins to the composite-motif DNA. Our study has therefore elucidated the central transcriptional mechanism of microglial activation in response to neurodegenerative condition.
ABSTRACT
Objective:To explore the function of IL-9 and PU.1 on genesis and development of pulmonary fibrosis,and the effect of active vitamin D3[1,25(OH)2VD3] on the expression levels of this two factors during the pathogenesis of fibrosis.Methods: 90 male SD rats were randomly divided into model group,treatment group,control group (n=30).Bleomycin(5 mg/kg) was injected into the trachea of rats to establish the model of pulmonary fibrosis in the model group and treatment group,while the control group was injected with isopyknic sterile saline.The treatment group,the model group and the control group were injected intraperitoneally with active vitamin D3,solvent of vitamin D3 (propylene glycol) and sterile saline on the 2nd day after surgery respectively.All injections were carried out once every other day.10 rats were euthanized at 14th,21st and 28th day in each group in turn.After obtaining lung tissues from experimental rats,the pathological change of lung was compared by hematoxylin-eosin staining.The difference of collagen fiber and hydroxyproline content were compared by the Masson staining and basic-hydrolysis method respectively.The mRNA and protein expression of IL-9 and PU.1 in lung tissue were detected by Real-time PCR and immunohistochemical technology respectively.The expression of IL-9 in serum was detected by ELISA.Results: Fibrosis appeared in lungs of experimental rats treated with bleomycin after 14 days,and more and more aggravated with time.At three time points,the hydroxyproline content in model group and treatment group were significantly higher than that of control group,and the treatment group was significantly lower than the model group.At three time points,the expression of IL-9 and PU.1 in model group and treatment group were risen gradually,and obviously higher than that in control group.On the 14th and 21st day,the expression of two factors in treatment group was significantly lower than model group;on the 28th day,there was no statistically significant difference between treatment group and model group(P>0.05).In model group and treatment group,the expression of two factors on 21st day was significantly higher than that on 14th day;there was no statistically significant difference between the 28th day and the 21st day.Conclusion: IL-9 and PU.1 may play a profibrotic role at early stage of pulmonary fibrosis induced by bleomycin.The active vitamin D3 may lower the expression level of PU.1,and then reduce the secretion of IL-9,thus may play an inhibiting effect on genesis and development of pulmonary fibrosis in rats.
ABSTRACT
Aim To investigate the effects of aspirin on Epstein-Barr virus (EBV)-transformed human B-lym-phocytes.Methods EBV-transformed human B-lym-phocytes were treated with certain concentrations of as-pirin.Cellular proliferation was analyzed by MTT as-say.Further evaluation of apoptosis of aspirin-treated cells was performed through light-field microscope, transmission electronic microscope(TEM),propidium iodide(PI)staining and flow cytometric analysis and DNA electrophoresis. Finally, immunoblot analysis was used to determine the expression levels of apopto-sis-associated proteins, proteins involved in mTOR pathway and PU.1 -Bim axis.Results Aspirin treat-ment inhibited proliferation of EBV-transformed human B-lymphocytes.We observed that aspirin treatment in-duced apoptosis in EBV-transformed human B-lympho-cytes,resulting in the decreased number and size of cells.Ultramicroscopic structural analysis via TEM in-dicated that aspirin treatment deformed the cellular nu-cleus,and led to peripheral chromatin and cytoplasmic vacuole.PI staining and flow cytometric analysis indi-cated that aspirin increased the permeability of cell membrane and decreased the viability of treated cells. Agarose electrophoresis revealed DNA smear in aspirin-treated cells.Mechanistically,mTOR signaling was in-hibited in aspirin-treated cells,as evidenced by the de-creased phosphorylation of S6K1 and S6 via immunob-lot analysis.Aspirin treatment led to the decrease of hematopoietic transcription factor PU.1 .Consequently, pro-apoptotic Bim, apoptosis-associated proteins caspase-3 and PARP were activated in aspirin-treated cells.Conclusion Aspirin may show anti-lymphoma effects via its inhibition of proliferation and induction of apoptosis of EBV-transformed human B-lymphocytes, in which mTOR signal pathway and PU.1 -Bim axis may be involved.
ABSTRACT
CCR3 is a chemokine receptor that mediates the accumulation of allergic inflammatory cells, including eosinophils and Th2 cells, at inflamed sites. The regulatory sequence of the CCR3 gene, contains two Runt-related transcription factor (RUNX) 1 sites and two PU.1 sites, in addition to a functional GATA site for transactivation of the CCR3 gene. In the present study, we examined the effects of the cis-acting elements of RUNX1 and PU.1 on transcription of the gene in EoL-1 eosinophilic cells and Jurkat T cells, both of which expressed functional surface CCR3 and these two transcription factors. Introduction of RUNX1 siRNA or PU.1 siRNA resulted in a modest decrease in CCR3 reporter activity in both cell types, compared with transfection of GATA-1 siRNA. Cotransfection of the two siRNAs led to inhibition in an additive manner. EMSA analysis showed that RUNX1, in particular, bound to its binding motifs. Mutagenesis analysis revealed that all point mutants lacking RUNX1- and PU.1-binding sites exhibited reduced reporter activities. These results suggest that RUNX1 and PU.1 participate in transcriptional regulation of the CCR3 gene.
Subject(s)
Eosinophils , Mutagenesis , RNA, Small Interfering , T-Lymphocytes , Th2 Cells , Transcription Factors , Transcriptional Activation , TransfectionABSTRACT
Objective PU.1 plays a key role in innate immune function in the alveolar macrophage.This study was to con-struct and identify recombinant adenovirus vectors carrying the human transcription factor PU.1 gene. Methods The recombinant shut-tle plasmid was obtained from the PU.1 gene ( SPI1) and eukaryotic expression vector that digested by restriction enzymes and connected by T4 DNA ligase.The target fragment SPI1-IRES-EGFP was amplified by PCR.The product was cloned into the intermediate pDONR221 and then recombined with the adenovirus backbone plasmid pAd/CMV/V5-DEST to form a recombinant adenovirus vector. The recombinant adenovirus vector was linearized by PacI and then transfected into human embryonic kidney (HEK293) cells to obtain the recombinant adenovirus pAD-SPI1-IRES-EGFP, which was then propagated in HEK293 cells, filtered and purified to obtain high-con-centration adenoviruses.The adenovirus titer was determined by TCID 50 assay.The PU.1 gene expression in the HEK293 cells was con-firmed by fluorescence microscopy and real-time qPCR. Results PCR amplification, restriction digestion and sequencing analysis showed the recombinant adenovirus carried the correct PU.1 gene.The final virus titer, calculated by TCID 50, was 8 ×1011 IU/mL. Green fluorescence was observed under the fluorescence microscope. Real-time qPCR confirmed that the expression of PU.1 mRNA was increased by 2189.93 folds. Conclusion The recombinant adenovirus vector carrying the PU.1 gene was constructed and obtained successfully, which could contribute to further studies of the influence of PU.1 overex-pression on the innate defense against Aspergillus fumigatus.
ABSTRACT
Aim To investigate the effect of resveratrol on proliferation and differentiation in K562 cells. Methods K562 cells were treated with different con-centrations of resveratrol for 6d. The colony number of K562 cells was detected with semi-solid culture assay. Expression of GATA-1 and PU. 1 in K562 cells was re-spectively measured with immunocytochemistry and Western blot. Expression of differentiation related anti-gen, CD11b, CD14 and CD42b, was measured with flowcytometry on K562 cells. Results Resveratrol could significantly decrease the colony number of K562 cells in a dose-dependent manner, and enhance the ex-pression of GATA-1,PU. 1,CD11b, CD14 and CD42b in K562 cells. Conclusion Resveratrol could inhibit the proliferation and induce differentiation of K562 cells via up-regulating the expression of GATA-1 and PU. 1 protein.
ABSTRACT
This study was aimed to investigate the effect of Bu-Shen Y i-Sui Sheng-Xue (BSYSSX) method on pro-liferation and differentiation mechanisms of hematopoietic progenitor cells. The rat models were established by 60Co-γrays and cyclophosphamide. Compound Chinese medicine was gavaged to rats of the normal control group, model group, stanozolol group, Yi-Sui Sheng-Xue (YSSX) group, Wen-Shen Sheng-Xue(WSSX) group and Zi-Shen Sheng-Xue (ZSSX) group. Then, serum of rat was prepared. Rat bone marrow cells were incubated with AA rats serum ac-counted for 20% and the number of hematopoietic progenitor cells colony-forming units (CFU) were counted. The level of GATA-1 and PU.1 mRNA in colony cells were detected with RT-PCR. The results showed that compared with the normal control group, the number of bone marrow cells, CFU-E, BFU-E, CFU-GM, as well as the expres-sion of GATA-1 and PU.1 mRNA in the model group decreased significantly (P< 0.01). Compared with the model group, the number of bone marrow cells, CFU-E, BFU-E, CFU-GM of each treatment group were significantly in-creased (P< 0.01). CFU-E and BFU-E of the ZSSX group were better than the YSSX group (P < 0.01). CFU-GM of the ZSSX group was better than the YSSX group and the WSSX group. The expression of GATA-1 and PU.1 mR-NA in each treatment group were significantly higher than the model group (P< 0.01). The expression of GATA-1 mRNA in the ZSSX group was better than the YSSZ group and WSSX group (P< 0.05). The expression of PU.1 mR-NA in the ZSSX group was higher than the YSSX group and WSSX group. It was concluded that BSYSSX method may increase the expression of GATA-1 and PU.1 mRNA in order to promote the proliferation and differentiation of bone marrow hematopoietic progenitor cells. The ZSSX method was better than the YSSX method and WSSX method.
ABSTRACT
BACKGROUND: Macrophages are one of the most important inflammatory cells in innate immunity. PU.1 is a macrophage-specific transcription factor. Ubiquitins are the ultimate regulator of eukaryotic transcription. The ubiquitination process for PU.1 is unknown. This study investigated the lipopolysaccharide (LPS)-induced activation of PU.1 and its relation to ubiquitins in the macrophages. METHODS: Raw264.7 cells, the primary cultured alveolar, pulmonary, and bone marrow derived macrophages were used. The Raw264.7 cells were treated with MG-132, NH4Cl, lactacytin and LPS. Nitric oxide and prostaglandin D2 and E2 were measured. Immunoprecipitation and Western blots were used to check ubiquitination of PU.1. RESULTS: The PU.1 ubiquitination increased after LPS (1 microg/mL) treatment for 4 hours on Raw264.7 cells. The ubiquitination of PU.1 by LPS was increased by MG-132 or NH4Cl pretreatment. Two hours of LPS treatment on macrophages, PU.1 activation was not induced nor increased with the inhibition of proteasomes and/or lysosomes. The ubiquitination of PU.1 was increased in LPS-treated Raw264.7 cells at 12- and at 24 hours. LPS-treated cells increased nitric oxide production, which was diminished by MG-132 or NH4Cl. LPS increased the production of PGE2 in the alveolar and peritoneal macrophages of wild type mice; however, PGE2 was blocked or diminished in Rac2 null mice. Pretreatment of lactacystin increased PGE2, however it decreased the PGD2 level in the macrophages derived from the bone marrow of B57/BL6 mice. CONCLUSION: LPS treatment in the macrophages ubiquitinates PU.1. Ubiquitination of PU.1 may be involved in synthesis of nitric oxide and prostaglandins.