Necroptosis in pulmonary macrophages promotes silica-induced inflammation and interstitial fibrosis in mice.

Silicosis is a disease characterized by extensive lung nodules and fibrosis caused by the prolonged inhalation of silica in occupational settings. However, the molecular mechanism of silicosis development is complex and not fully understood. Furthermore, the role of necroptosis, a death receptor-mediated and caspase-independent mode of inflammatory cell death, is not well understood in silicosis. Here, we demonstrate that the necroptotic signaling pathway of macrophages is significantly activated in the lungs of silicosis mouse models. Meanwhile, increased M1 macrophage infiltration and up-regulation of pro-inflammatory cytokines (TNF-α, IL-6) were observed in our silicosis model. Notably, the expression of the pro-fibrotic factor, TGF-ß1, and fibrosis biomarkers α-SMA and collagen I were also unregulated; however, these phenomena were recovered by Nec-1, an inhibitor specific for RIP1 kinase-dependent necroptosis. We conclude that macrophage-mediated necroptosis promotes the progression of silicosis by enhancing lung inflammatory responses and fibrogenesis in a mouse model of silicosis. These findings provide new insights for drug discovery and clinical treatment of silicosis.

[Effect of cigarette smoke extract on RAW264. 7 cell proliferation, autophagy and its mechanism].

OBJECTIVE: To inquiry the effects of cigarette smoke extract(CSE) on RAW264. 7 cell proliferation, autophagy and its mechanism. METHODS: RAW264. 7 cell were used and divided into control, starvation and CSE group(2%, 3%, 4%, 5%CSE). CCK-8 was used to detect the toxic action of CSE on RAW264. 7 cell. Western blot and mRFP-GFP-LC3 cell fluorescence spot count were used to explore the function of CSE on RAW264. 7 cell autophagy and its mechanism. RESULTS: Compared with the control group, the result of CCK-8(0. 671 ± 0. 03、0. 746± 0. 10、0. 584 ± 0. 07、0. 588±0. 05) showed that CSE inhibit the proliferation of RAW 264. 7 cell on 24 hours, the difference was statistically significant(P < 0. 05). The outcomes of Western blot showed that, compared with the control group, LC3 B in the CSE group increased, difference in 6(6. 612 ± 0. 35)/12(4. 383 ± 1. 99)/24(5. 781 ± 0. 78) hours, while P62 decreased in 6(1. 815±0. 08)/12(4. 383±1. 99)/24(0. 414±0. 06) hours also different, P-mTOR(1. 744 ± 0. 15) and P-AKT(0. 376 ± 0. 03) decreased, the difference was statistically significant(P<0. 05), but Beclin1 was not significantly changed. The mRFP-GFP-LC3 cell fluorescence spot count showed that the green fluorescence spot(GFP)decreased and the red fluorescence spot(mRFP) remained stable in CSE group, combined mRFP-GFP is shown as yellow and red spots. CONCLUSION: CSE has toxic effect on cell proliferation and leads to RAW264. 7 cell autophagy enhanced through AKT/m TOR pathways.

TLR2 Arg753Gln Gene Polymorphism Associated with Tuberculosis Susceptibility: An Updated Meta-Analysis.

OBJECTIVE: To date, a series of studies were conducted to investigate the association between TLR2 (Toll-like receptor 2) Arg753Gln gene polymorphism and tuberculosis (TB). However, the results were inconsistent. This meta-analysis was performed to elucidate the roles of TLR2 Arg753Gln gene polymorphism in TB. METHODS: All available articles were searched from online databases such as PubMed, Medline, CNKI, and Wanfang. Statistical analyses were performed using the STATA12.0 (Stata Corp LP, College Station, TX, United States) software. RESULTS: 32 case-control studies comprising 5943 cases and 5991 controls were identified in this meta-analysis. Overall, the TLR2 Arg753Gln gene polymorphism was associated with high TB risk in allele model (A vs. G: OR=2.20, 95%CI=1.60-3.04, P≤0.01), dominant model (AA+AG vs. GG: OR=2.70, 95%CI=2.00-3.65, P≤0.01), and heterozygote model (AG vs. GG contrast: OR=2.97, 95%CI=2.39-3.69, P≤0.01). Subgroup analysis by ethnicity indicated that the A allele increased susceptibility to TB in Asian (OR=3.35, 95%CI=2.36-4.74) and Caucasian populations (OR=2.62, 95%CI=1.77-3.87), but not in African (2.08, 95%CI=0.62-2.72) or mixed populations (OR=0.76, 95%CI=0.36-1.14). Stratified analysis by sample type suggested that the A allele associated with high pulmonary tuberculosis (PTB) risks (OR=2.43, 95%CI=1.66-3.54), but not with extra pulmonary tuberculosis (EPTB) (OR=1.84, 95%CI=0.83-4.06). CONCLUSION: this meta-analysis suggested the following: (1) TLR2 Arg753Gln polymorphism is significantly associated with high TB risk. (2) In subgroup analysis based on ethnicity, TLR2 Arg753Gln polymorphism elevates the risk of TB in Asian and Caucasian populations, but not in African or mixed populations. (3) Stratified by sample type, TLR2 Arg753Gln polymorphism is associated with increased PTB risk, but not with EPTB.

Human U3 protein14a is a novel type ubiquitin ligase that binds RB and promotes RB degradation depending on a leucine-rich region.

The nucleolar protein hUTP14a promotes p53 degradation and possesses an oncogene potential. Here, we report that hUTP14a promotes degradation of tumor suppressor retinoblastoma (RB) protein. Sequences alignment showed that hUTP14a contains the RB-binding PENF motif in its C-terminus. We showed that hUTP14a interacted with RB in vivo and in vitro. Further, hUTP14a promoted polyubiquitination and proteasome-dependent turnover of RB. Importantly, purified Flag-hUTP14a facilitated RB ubiquitination in vitro, demonstrating that hUTP14a is an ubiquitin E3 ligase for RB. A BLAST alignment with hUTP14a does not reveal a RING or HECT domain. To define the conserved domain for E3 ligase activity in hUTP14a, the minimum domain for promoting RB degradation was mapped to residues 61-120 of hUTP14a, in which a leucine-rich region (LRR) LxLxxLL was suggested to be conserved. Flag-hUTP14a (ΔLRR), Flag-hUTP14a-MT1(LxLxxLL to LxLxxAA) and Flag-hUTP14a-MT2(LxLxxLL to AxAxxAA) lost the capability of ubiquitinating RB in vitro, demonstrating that LRR is required for the E3 ligase activity of hUTP14a. Consequently, expression of hUTP14a caused upregulation of E2F1 downstream genes, thus promoting cancer cell proliferation. Taken together, we demonstrate that hUTP14a promotes RB degradation through its E3 ligase activity and suggest that the LRR could be a potential conserved E3 ligase domain.

Crosstalk between autophagy and intracellular radiation response (Review).

Autophagy induced by radiation is critical to cell fate decision. Evidence now sheds light on the importance of autophagy induced by cancer radiotherapy. Traditional view considers radiation can directly or indirectly damage DNA which can activate DNA damage the repair signaling pathway, a large number of proteins participating in DNA damage repair signaling pathway such as p53, ATM, PARP1, FOXO3a, mTOR and SIRT1 involved in autophagy regulation. However, emerging recent evidence suggests radiation can also cause injury to extranuclear targets such as plasma membrane, mitochondria and endoplasmic reticulum (ER) and induce accumulation of ceramide, ROS, and Ca2+ concentration which activate many signaling pathways to modulate autophagy. Herein we review the role of autophagy in radiation therapy and the potent intracellular autophagic triggers induced by radiation. We aim to provide a more theoretical basis of radiation-induced autophagy, and provide novel targets for developing cytotoxic drugs to increase radiosensitivity.

125I Seeds Radiation Induces Paraptosis-Like Cell Death via PI3K/AKT Signaling Pathway in HCT116 Cells.

125I seeds brachytherapy implantation has been extensively performed in unresectable and rerecurrent rectal carcinoma. Many studies on the cancer-killing activity of 125I seeds radiation mainly focused on its ability to trigger apoptosis, which is the most well-known and dominant type of cell death induced by radiation. However our results showed some unique morphological features such as cell swelling, cytoplasmic vacuolation, and plasma membrane integrity, which is obviously different to apoptosis. In this study, clonogenic proliferation was carried out to assay survival fraction. Transmission electron microscopy was used to analyze ultrastructural and evaluate morphologic feature of HCT116 cells after exposure to 125I seeds radiation. Immunofluorescence analysis was used to detect the origin of cytoplasmic vacuoles. Flow cytometry analysis was employed to detect the size and granularity of HCT116 cells. Western blot was performed to measure the protein level of AIP1, caspase-3, AKT, p-Akt (Thr308), p-Akt (Ser473), and ß-actin. We found that 125I seeds radiation activated PI3K/AKT signaling pathway and could trigger paraptosis-like cell death. Moreover, inhibitor of PI3K/AKT signaling pathway could inhibit paraptosis-like cell death induced by 125I seeds radiation. Our data suggest that 125I seeds radiation can induce paraptosis-like cell death via PI3K/AKT signaling pathway.

The Protective Roles of ROS-Mediated Mitophagy on 125I Seeds Radiation Induced Cell Death in HCT116 Cells.

For many unresectable carcinomas and locally recurrent cancers (LRC), 125I seeds brachytherapy is a feasible, effective, and safe treatment. Several studies have shown that 125I seeds radiation exerts anticancer activity by triggering DNA damage. However, recent evidence shows mitochondrial quality to be another crucial determinant of cell fate, with mitophagy playing a central role in this control mechanism. Herein, we found that 125I seeds irradiation injured mitochondria, leading to significantly elevated mitochondrial and intracellular ROS (reactive oxygen species) levels in HCT116 cells. The accumulation of mitochondrial ROS increased the expression of HIF-1α and its target genes BINP3 and NIX (BINP3L), which subsequently triggered mitophagy. Importantly, 125I seeds radiation induced mitophagy promoted cells survival and protected HCT116 cells from apoptosis. These results collectively indicated that 125I seeds radiation triggered mitophagy by upregulating the level of ROS to promote cellular homeostasis and survival. The present study uncovered the critical role of mitophagy in modulating the sensitivity of tumor cells to radiation therapy and suggested that chemotherapy targeting on mitophagy might improve the efficiency of 125I seeds radiation treatment, which might be of clinical significance in tumor therapy.

Chemokine (C-C motif) ligand 5 -28C>G is significantly associated with an increased risk of tuberculosis: a meta-analysis.

OBJECTIVE: Chemokine (C-C motif) ligand 5 (CCL5) has been shown to play an important role in antimycobacterial immune responses. Previous studies have extensively reported that the CCL5 -28C>G gene polymorphism is associated with susceptibility to tuberculosis (TB). However, the results of these studies have been inconsistent. To investigate the relationship between the CCL5 -28C>G and the risk of TB, we performed a meta-analysis. METHODS: We searched articles published before June 6, 2014 from PubMed, CNKI, and Wanfang databases. Data were extracted from all eligible publications independently by two investigators and statistically analyzed. Odds ratios (OR) with 95% confidence intervals (CI) were calculated to assess the strength of the association between CCL5 polymorphism and TB. RESULTS: Four case-control studies including 647 TB cases and 726 controls were involved in the meta-analysis. Our meta-analysis indicated the CCL5 -28C>G gene polymorphism was significantly associated with increased risk of TB (G vs. C: 3.75, 95% CI = 1.76-7.99; GG vs. CC: OR = 30.26, 95% CI = 14.28-64.12). CONCLUSION: Our results suggested that the -28C>G polymorphism is significantly associated with higher TB risk, which is opposite from previously published reports. However, the number of the study is limited, additional well-designed studies are required to elucidate the association between the CCL5 -28C>G gene polymorphism and TB.

[Changes and the implications of CD4(+);CD25(+);CD127(low); regulatory T cells in drug addicts during natural drug withdrawal].

OBJECTIVE: To study the changes of CD4(+);CD25(+);CD127(low); regulatory T cells (Tregs) and transforming growth factor beta 1 (TGF-ß1) mRNA in peripheral blood mononuclear cells (PBMCs) in drug addicts during natural drug withdrawal, and explore the effects of addictive drugs on their Tregs. METHODS: Peripheral blood was collected from 40 drug addicts with 6-month natural withdrawal, 40 cases with 18-month natural withdrawal and 30 healthy controls. Then the Tregs were counted by flow cytometry and TGF-ß1 mRNA expression in PBMCs was detected by RT-PCR. RESULTS: Compared with the controls, Tregs and TGF-ß1 mRNA expression in PBMCs increased significantly in the group with one 18-month natural withdrawal, but no significant difference was found in the group with 6-month natural withdrawal. CONCLUSION: Addictive drugs have a long-term effect on the Tregs in drug addicts, and the abnormal Tregs may result in the immune dysfunction in drug addicts.

Transcriptional repressor NIR functions in the ribosome RNA processing of both 40S and 60S subunits.

BACKGROUND: NIR was identified as an inhibitor of histone acetyltransferase and it represses transcriptional activation of p53. NIR is predominantly localized in the nucleolus and known as Noc2p, which is involved in the maturation of the 60S ribosomal subunit. However, how NIR functions in the nucleolus remains undetermined. In the nucleolus, a 47S ribosomal RNA precursor (pre-rRNA) is transcribed and processed to produce 18S, 5.8S and 28S rRNAs. The 18S rRNA is incorporated into the 40S ribosomal subunit, whereas the 28S and 5.8S rRNAs are incorporated into the 60S subunit. U3 small nucleolar RNA (snoRNA) directs 18S rRNA processing and U8 snoRNA mediates processing of 28S and 5.8 S rRNAs. Functional disruption of nucleolus often causes p53 activation to inhibit cell proliferation. METHODOLOGY/PRINCIPAL FINDINGS: Western blotting showed that NIR is ubiquitously expressed in different human cell lines. Knock-down of NIR by siRNA led to inhibition of the 18S, 28S and 5.8S rRNAs evaluated by pulse-chase experiment. Pre-rRNA particles (pre-rRNPs) were fractionated from the nucleus by sucrose gradient centrifugation and analysis of the pre-RNPs components showed that NIR existed in the pre-RNPs of both the 60S and 40S subunits and co-fractionated with 32S and 12S pre-rRNAs in the 60S pre-rRNP. Protein-RNA binding experiments demonstrated that NIR is associated with the 32S pre-rRNA and U8 snoRNA. In addition, NIR bound U3 snoRNA. It is a novel finding that depletion of NIR did not affect p53 protein level but de-repressed acetylation of p53 and activated p21. CONCLUSIONS: We provide the first evidence for a transcriptional repressor to function in the rRNA biogenesis of both the 40S and 60S subunits. Our findings also suggested that a nucleolar protein may alternatively signal to p53 by affecting the p53 modification rather than affecting p53 protein level.

A small ribosomal subunit (SSU) processome component, the human U3 protein 14A (hUTP14A) binds p53 and promotes p53 degradation.

Ribosome biogenesis is required for normal cell function, and aberrant ribosome biogenesis can lead to p53 activation. However, how p53 is activated by defects of ribosome biogenesis remains to be determined. Here, we identified human UTP14a as an SSU processome component by showing that hUTP14a is nucleolar, associated with U3 snoRNA and involved in 18 S rRNA processing. Interestingly, ectopic expression of hUTP14a resulted in a decrease and knockdown of hUTP14a led to an increase of p53 protein levels. We showed that hUTP14a physically interacts with p53 and functionally promotes p53 turn-over, and that hUTP14a promotion of p53 destabilization is sensitive to a proteasome inhibitor but independent of ubiquitination. Significantly, knockdown of hUTP14a led to cell cycle arrest and apoptosis. Our data identified a novel pathway for p53 activation through a defect in rRNA processing and suggest that a ribosome biogenesis factor itself could act as a sensor for nucleolar stress to regulate p53.

hALP, a novel transcriptional U three protein (t-UTP), activates RNA polymerase I transcription by binding and acetylating the upstream binding factor (UBF).

Transcription of ribosome RNA precursor (pre-rRNA) and pre-rRNA processing are coordinated by a subset of U three proteins (UTPs) known as transcriptional UTPs (t-UTPs), which participate in pre-rRNA transcription in addition to participation in 18 S rRNA processing. However, the mechanism by which t-UTPs function in pre-rRNA transcription remains undetermined. In the present study, we identified hALP, a histone acetyl-transferase as a novel t-UTP. We first showed that hALP is nucleolar, and is associated with U3 snoRNA and required for 18 S rRNA processing. Moreover, depletion of hALP resulted in a decreased level of 47 S pre-rRNA. Ectopic expression of hALP activated the rDNA promoter luciferase reporter and knockdown of hALP inhibited the reporter. In addition, hALP bound rDNA. Taken together these data identify hALP as a novel t-UTP. Immunoprecipitation and GST pulldown experiments showed that hALP binds the upstream binding factor (UBF) in vivo and in vitro. It is of importance that hALP acetylated UBF depending on HAT in vivo, and hALP but not hALP (ΔHAT) facilitated the nuclear translocation of the RNA polymerase I (Pol I)-associated factor 53 (PAF53) from the cytoplasm and promoted the association of UBF with PAF53. Thus, we provide a mechanism in which a novel t-UTP activates Pol I transcription by binding and acetylating UBF.

1A6/DRIM, a novel t-UTP, activates RNA polymerase I transcription and promotes cell proliferation.

BACKGROUND: Ribosome biogenesis is required for protein synthesis and cell proliferation. Ribosome subunits are assembled in the nucleolus following transcription of a 47S ribosome RNA precursor by RNA polymerase I and rRNA processing to produce mature 18S, 28S and 5.8S rRNAs. The 18S rRNA is incorporated into the ribosomal small subunit, whereas the 28S and 5.8S rRNAs are incorporated into the ribosomal large subunit. Pol I transcription and rRNA processing are coordinated processes and this coordination has been demonstrated to be mediated by a subset of U3 proteins known as t-UTPs. Up to date, five t-UTPs have been identified in humans but the mechanism(s) that function in the t-UTP(s) activation of Pol I remain unknown. In this study we have identified 1A6/DRIM, which was identified as UTP20 in our previous study, as a t-UTP. In the present study, we investigated the function and mechanism of 1A6/DRIM in Pol I transcription. METHODOLOGY/PRINCIPAL FINDINGS: Knockdown of 1A6/DRIM by siRNA resulted in a decreased 47S pre-rRNA level as determined by Northern blotting. Ectopic expression of 1A6/DRIM activated and knockdown of 1A6/DRIM inhibited the human rDNA promoter as evaluated with luciferase reporter. Chromatin immunoprecipitation (ChIP) experiments showed that 1A6/DRIM bound UBF and the rDNA promoter. Re-ChIP assay showed that 1A6/DRIM interacts with UBF at the rDNA promoter. Immunoprecipitation confirmed the interaction between 1A6/DRIM and the nucleolar acetyl-transferase hALP. It is of note that knockdown of 1A6/DRIM dramatically inhibited UBF acetylation. A finding of significance was that 1A6/DRIM depletion, as a kind of nucleolar stress, caused an increase in p53 level and inhibited cell proliferation by arresting cells at G1. CONCLUSIONS: We identify 1A6/DRIM as a novel t-UTP. Our results suggest that 1A6/DRIM activates Pol I transcription most likely by associating with both hALP and UBF and thereby affecting the acetylation of UBF.