Canonical and non-canonical functions of p53 isoforms: potentiating the complexity of tumor development and therapy resistance.

Full-length p53 (p53α) plays a pivotal role in maintaining genomic integrity and preventing tumor development. Over the years, p53 was found to exist in various isoforms, which are generated through alternative splicing, alternative initiation of translation, and internal ribosome entry site. p53 isoforms, either C-terminally altered or N-terminally truncated, exhibit distinct biological roles compared to p53α, and have significant implications for tumor development and therapy resistance. Due to a lack of part and/or complete C- or N-terminal domains, ectopic expression of some p53 isoforms failed to induce expression of canonical transcriptional targets of p53α like CDKN1A or MDM2, even though they may bind their promoters. Yet, p53 isoforms like Δ40p53α still activate subsets of targets including MDM2 and BAX. Furthermore, certain p53 isoforms transactivate even novel targets compared to p53α. More recently, non-canonical functions of p53α in DNA repair and of different isoforms in DNA replication unrelated to transcriptional activities were discovered, amplifying the potential of p53 as a master regulator of physiological and tumor suppressor functions in human cells. Both regarding canonical and non-canonical functions, alternative p53 isoforms frequently exert dominant negative effects on p53α and its partners, which is modified by the relative isoform levels. Underlying mechanisms include hetero-oligomerization, changes in subcellular localization, and aggregation. These processes ultimately influence the net activities of p53α and give rise to diverse cellular outcomes. Biological roles of p53 isoforms have implications for tumor development and cancer therapy resistance. Dysregulated expression of isoforms has been observed in various cancer types and is associated with different clinical outcomes. In conclusion, p53 isoforms have expanded our understanding of the complex regulatory network involving p53 in tumors. Unraveling the mechanisms underlying the biological roles of p53 isoforms provides new avenues for studies aiming at a better understanding of tumor development and developing therapeutic interventions to overcome resistance.

Independent and joint association of physical activity and adequate weekday sleep duration with metabolic dysfunction-associated steatotic liver disease.

BACKGROUND: The independent and joint association of physical activity (PA) and weekday sleep duration with metabolic dysfunction-associated steatotic liver disease (MASLD) remain unclear. AIMS: We intended to explore this association in the United States. METHODS: This cross-sectional study recruited 4974 individuals from the National Health and Nutrition Examination Survey between 2017 and 2018. Information regarding PA and weekday sleep duration was obtained through questionnaires. Metabolic associated fatty liver disease (MAFLD) was diagnosed by transient elastography based on the consensus definitions. Multivariable logistic regression models were employed to investigate the independent and joint association of PA and weekday sleep duration with MAFLD. RESULTS: Of the 4974 subjects, engaging in active PA or sustaining adequate sleep duration was associated with decreased the odds of MAFLD (p < 0.05). Specifically, active leisure-time PA was linked to lower 37 % odds of MAFLD (OR, 0.63; 95 % CI, 0.55-0.73). Individuals who had one to twice times (150-299 min/week) or more than twice (≥300 min/week) the recommended amount of leisure-time PA by PA Guidelines had 19 % (OR, 0.81; 95 % CI, 0.67-0.99) and 45 % (OR, 0.55; 95 % CI, 0.47-0.65) lower odds of MAFLD, respectively (P for trend <0.001). Individuals with adequate weekday sleep duration was associated with 24 % lower odds of MAFLD (OR, 0.76;95 % CI,0.67-0.88). Notably, active PA combined with adequate weekday sleep duration significantly decreased the odds ratios for MAFLD by 35 % (OR: 0.65, 95 % CI, 0.52-0.80). However, in individuals with significant alcohol use, the joint effect of total PA and weekday sleep duration on MAFLD was not statistically significant. CONCLUSIONS: Both active PA and adequate weekday sleep duration were inversely associated with the risk of MASLD independently, while combining them could further lower the risk of MASLD.

The levels of p53 govern the hierarchy of DNA damage tolerance pathway usage.

It is well-established that, through canonical functions in transcription and DNA repair, the tumor suppressor p53 plays a central role in safeguarding cells from the consequences of DNA damage. Recent data retrieved in tumor and stem cells demonstrated that p53 also carries out non-canonical functions when interacting with the translesion synthesis (TLS) polymerase iota (POLι) at DNA replication forks. This protein complex triggers a DNA damage tolerance (DDT) mechanism controlling the DNA replication rate. Given that the levels of p53 trigger non-binary rheostat-like functions in response to stress or during differentiation, we explore the relevance of the p53 levels for its DDT functions at the fork. We show that subtle changes in p53 levels modulate the contribution of some DDT factors including POLι, POLη, POLζ, REV1, PCNA, PRIMPOL, HLTF and ZRANB3 to the DNA replication rate. Our results suggest that the levels of p53 are central to coordinate the balance between DDT pathways including (i) fork-deceleration by the ZRANB3-mediated fork reversal factor, (ii) POLι-p53-mediated fork-slowing, (iii) POLι- and POLη-mediated TLS and (iv) PRIMPOL-mediated fork-acceleration. Collectively, our study reveals the relevance of p53 protein levels for the DDT pathway choice in replicating cells.

Divergent summertime surface O3 pollution formation mechanisms in two typical Chinese cities in the Beijing-Tianjin-Hebei region and Fenwei Plain.

Recently, severe summertime ozone (O3) pollution has swept across most areas of China, especially the Beijing-Tianjin-Hebei (BTH) region and Fenwei Plain. By focusing on Beijing and Yuncheng, which are two typical cities in the BTH region and the Fenwei Plain, we intended to reveal the neglected fact that they had disparate emission features and atmospheric movements but suffered from similar high-O3 pollution levels. Field observations indicated that Yuncheng had lower volatile organic compound (VOC) and NOx concentrations but higher background O3 levels. The model simulation verified that both photochemical reactions and net O3 generation were stronger in Beijing. Ultimately, faster net O3 generation rates (8.4 ppbv/h) plus lower background O3 values in Beijing and lower net O3 generation rates (6.2 ppbv/h) plus higher background O3 values in Yuncheng caused both regions to reach similar O3 peak values in July 2020. However, different O3 control measures were appropriate for the two cities according to the different simulated O3-VOCs-NOx responses. Additionally, as surface O3 levels are greatly affected by the ongoing O3 production/depletion process that occurs in three dimensions, exploring the effects of spatially distributed O3 on surface O3 should be high on the agenda in the future.

GEF-H1 Transduces FcεRI Signaling in Mast Cells to Activate RhoA and Focal Adhesion Formation during Exocytosis.

When antigen-stimulated, mast cells release preformed inflammatory mediators stored in cytoplasmic granules. This occurs via a robust exocytosis mechanism termed degranulation. Our previous studies revealed that RhoA and Rac1 are activated during mast cell antigen stimulation and are required for mediator release. Here, we show that the RhoGEF, GEF-H1, acts as a signal transducer of antigen stimulation to activate RhoA and promote mast cell spreading via focal adhesion (FA) formation. Cell spreading, granule movement, and exocytosis were all reduced in antigen-stimulated mast cells when GEF-H1 was depleted by RNA interference. GEF-H1-depleted cells also showed a significant reduction in RhoA activation, resulting in reduced stress fiber formation without altering lamellipodia formation. Ectopic expression of a constitutively active RhoA mutant restored normal morphology in GEF-H1-depleted cells. FA formation during antigen stimulation required GEF-H1, suggesting it is a downstream target of the GEF-H1-RhoA signaling axis. GEF-H1 was activated by phosphorylation in conjunction with antigen stimulation. Syk kinase is linked to the FcεRI signaling pathway and the Syk inhibitor, GS-9973, blocked GEF-H1 activation and also suppressed cell spreading, granule movement, and exocytosis. We concluded that during FcεRI receptor stimulation, GEF-H1 transmits signals to RhoA activation and FA formation to facilitate the exocytosis mechanism.

Enzymatic Characterization and Coenzyme Specificity Conversion of a Novel Dimeric Malate Dehydrogenase from Bacillus subtilis.

Malate is an important material to various industrials and clinical applications. Bacillus subtilis is a widely used biocatalyst tool for chemical production. However, the specific enzymatic properties of malate dehydrogenase from Bacillus subtilis (BsMDH) remain largely unknown. In the present study, BsMDH was cloned, recombinantly expressed and purified to test its enzymatic properties. The molecular weight of single unit of BsMDH was 34,869.7 Da. Matrix-Assisted Laser-Desorption Ionization-Time-of-Flight Mass Spectrometry and gel filtration analysis indicated that the recombinant BsMDH could form dimers. The kcat/Km values of oxaloacetate and NADH were higher than those of malate and NAD+, respectively, indicating a better catalysis in the direction of malate synthesis than the reverse. Furthermore, six BsMDH mutants were constructed with the substitution of amino acids at the coenzyme binding site. Among them, BsMDH-T7 showed a greatly higher affinity and catalysis efficiency to NADPH than NADH with the degree of alteration of 2039, suggesting the shift of the coenzyme dependence from NADH to NADPH. In addition, BsMDH-T7 showed a relatively lower Km value, but a higher kcat and kcat/Km than NADPH-dependent MDHs from Thermus flavus and Corynebacterium glutamicum. Overall, these results indicated that BsMDH and BsMDH-T7 mutant might be promising enzymes for malate production.

Demonstration of a new entity of non-perforated appendicitis through studying cluster of appendicitis.

Differential diagnosis and management for perforated appendicitis and non-perforated appendicitis are current hot topics. The aim of this study is to demonstrate a new entity of non-perforated appendicitis, "acute hemorrhagic appendicitis" through studying cluster of acute appendicitis among Tibetan students at a high school in central China. Over the 11-year period, there were 120 patients with more female patients (102 of 499, 20.4%) than male patients (18 of 474, 3.8%) among 973 Tibetan students. 117 patients' clinical data were available. Clinical manifestations were identical to classic appendicitis. However, axilla temperature, white blood cell counts and neutrophil level were elevated mildly in 12 (10.3%), 19 (16.2%) and 12 (10.3%) patients respectively. Pathologically, the resected appendices exhibited focal or diffuse hemorrhages in mucosa and/or submucosa, and infiltration by eosinophil and by lymphocytes. No patients had perforated appendicitis. The median time from the onset to surgery was 3 days (IQR, 2-4). All patients were discharged with full recovery. In conclusion, "acute hemorrhagic appendicitis" represented a new entity of non-perforated appendicitis with unique cause and pathogenesis, which might be treated with antibiotics alone or self-limited. Studying the cluster is a reliable method to find new entity of appendicitis.

Cluster of Acute Appendicitis Among High School Tibetan Students in Nanchang, China: Investigation, Control, and Prevention.

Objective: Infectious etiology of acute appendicitis is a current hot topic. The most of study on appendicitis came from sporadic patients and focused on clinical treatment rather than control and prevention of appendicitis in the population. The present study aims to investigate the epidemiological features of cluster of acute appendicitis, risk factors, and evaluate effectiveness of control and prevention in population. Methods: We conducted longitudinal study on a cluster of acute appendicitis among Tibetan students at a high school in eastern China, which was divided into three stages: 1. We retrospectively collected epidemiological data and clinical data to explore risk factor and possible transmission route in August of 2005; 2. We conducted targeted measures from August of 2005 and analyzed incidence trend from 2000 to 2010; 3. Since no new patients occurred in 2011, we conducted surveillance from the beginning of 2012 until July 2018. Results: Among 973 Tibetan students, there were 120 patients with more female patients (102 of 499, 20.4%) than male patients (18 of 474, 3.8%) from January of 2000 to December of 2010. The 4-year cumulative incidence rates in female students enrolled in 2001, 2002, 2003, 2004, 2005, 2006 were 26.8% (11 of 41), 27.1% (13 of 48), 44.7% (21 of 47), 42.4% (14 of 33), 23.1% (9 of 39), and 19.3% (11 of 57), respectively before their graduation. There was a clustering feature. Mutual contact with patients before the onset of symptoms was an important risk factor (Adjusted OR 4.89, 95% CI: 1.67-14.35). Transmission route may be fecal-oral infection. Before conducting targeted measures, the incidence rate increased from 2000 and peaked in 2005. After conducting targeted measures, the incidence rate decreased year by year until 2010. Under surveillance from January of 2012 to July of 2018, only four sporadic patients occurred at this school. Conclusion: This cluster of acute appendicitis had features of an infectious disease in epidemiology, which can be controlled and prevented by targeted measures. Our study may also be used for prevention of sporadic patients and be generalized in general population as cluster of appendicitis occurred in many provinces of China.

Mast cell granule motility and exocytosis is driven by dynamic microtubule formation and kinesin-1 motor function.

Mast cells are tissue-resident immune cells that have numerous cytoplasmic granules which contain preformed pro-inflammatory mediators. Upon antigen stimulation, sensitized mast cells undergo profound changes to their morphology and rapidly release granule mediators by regulated exocytosis, also known as degranulation. We have previously shown that Rho GTPases regulate exocytosis, which suggests that cytoskeleton remodeling is involved in granule transport. Here, we used live-cell imaging to analyze cytoskeleton remodeling and granule transport in real-time as mast cells were antigen stimulated. We found that granule transport to the cell periphery was coordinated by de novo microtubule formation and not F-actin. Kinesore, a drug that activates the microtubule motor kinesin-1 in the absence of cargo, inhibited microtubule-granule association and significantly reduced exocytosis. Likewise, shRNA knock-down of Kif5b, the kinesin-1 heavy chain, also reduced exocytosis. Imaging showed granules accumulated in the perinuclear region after kinesore treatment or Kif5b knock-down. Complete microtubule depolymerization with nocodazole or colchicine resulted in the same effect. A biochemically enriched granule fraction showed kinesin-1 levels increase in antigen-stimulated cells, but are reduced by pre-treatment with kinesore. Kinesore had no effect on the levels of Slp3, a mast cell granule cargo adaptor, in the granule-enriched fraction which suggests that cargo adaptor recruitment to granules is independent of motor association. Taken together, these results show that granules associate with microtubules and are driven by kinesin-1 to facilitate exocytosis.

MicroRNA-665-3p exacerbates nonalcoholic fatty liver disease in mice.

Oxidative stress and chronic inflammation are major culprits of nonalcoholic fatty liver disease (NAFLD). MicroRNA-665-3p (miR-665-3p) is implicated in regulating inflammation and oxidative stress; however, its role and molecular basis in NAFLD remain elusive. Herein, we measured a significant upregulation of miR-665-3p level in the liver and primary hepatocytes upon high fat diet (HFD) or 0.5 mmol/L palmitic acid plus 1.0 mmol/L oleic acid stimulation, and the elevated miR-665-3p expression aggravated oxidative stress, inflammation and NAFLD progression in mice. In contrast, miR-665-3p inhibition by the miR-665-3p antagomir significantly prevented HFD-induced oxidative stress, inflammation and hepatic dysfunction in vivo. Manipulation of miR-665-3p in primary hepatocytes also caused similar phenotypic alterations in vitro. Mechanistically, we demonstrated that miR-665-3p directly bound to the 3'-untranslated region of fibronectin type III domain-containing 5 (FNDC5) to downregulate its expression and inactivated the downstream AMP-activated protein kinase alpha (AMPKα) pathway, thereby facilitating oxidative stress, inflammation and NAFLD progression. Our findings identify miR-665-3p as an endogenous positive regulator of NAFLD via inactivating FNDC5/AMPKα pathway, and inhibiting miR-665-3p may provide novel therapeutic strategies to treat NAFLD.

High crop yield losses induced by potential HONO sources - A modelling study in the North China Plain.

Nitrous acid (HONO) is a major source of hydroxyl radicals in the troposphere through its photolysis, and can significantly influence ozone (O3) levels, thereby causing considerable crop yield losses. Previous studies have assessed relative crop yield losses by using exposure-response equations with observed or simulated O3, however, the contribution of enhanced O3 due to potential HONO sources to the crop yield losses has never been quantified. In this study, for the first time, we evaluated the crop yield losses caused by potential HONO sources in the North China Plain (NCP), which is one of the major grain-producing areas in China suffering from heavy O3 pollution, by using the Weather Research and Forecasting/Chemistry (WRF-Chem) model during the wheat and maize growing seasons of 2016. HONO simulations were significantly improved after including six potential HONO sources in the WRF-Chem model. The potential HONO sources produced a daily maximum 8-h O3 enhancement of 8.1/8.2 ppb during the wheat/maize growing seasons, respectively, and led to ~11.4%/3.3% relative yield losses for wheat/maize, respectively, corresponding to approximately US$3.78/0.66 billion losses, respectively, in NCP in 2016. The above results suggest that potential HONO sources play a significant role in O3 formation and could induce high crop yield losses globally.

p53 isoforms differentially impact on the POLι dependent DNA damage tolerance pathway.

The recently discovered p53-dependent DNA damage tolerance (DDT) pathway relies on its biochemical activities in DNA-binding, oligomerization, as well as complex formation with the translesion synthesis (TLS) polymerase iota (POLι). These p53-POLι complexes slow down nascent DNA synthesis for safe, homology-directed bypass of DNA replication barriers. In this study, we demonstrate that the alternative p53-isoforms p53ß, p53γ, Δ40p53α, Δ133p53α, and Δ160p53α differentially affect this p53-POLι-dependent DDT pathway originally described for canonical p53α. We show that the C-terminal isoforms p53ß and p53γ, comprising a truncated oligomerization domain (OD), bind PCNA. Conversely, N-terminally truncated isoforms have a reduced capacity to engage in this interaction. Regardless of the specific loss of biochemical activities required for this DDT pathway, all alternative isoforms were impaired in promoting POLι recruitment to PCNA in the chromatin and in decelerating DNA replication under conditions of enforced replication stress after Mitomycin C (MMC) treatment. Consistent with this, all alternative p53-isoforms no longer stimulated recombination, i.e., bypass of endogenous replication barriers. Different from the other isoforms, Δ133p53α and Δ160p53α caused a severe DNA replication problem, namely fork stalling even in untreated cells. Co-expression of each alternative p53-isoform together with p53α exacerbated the DDT pathway defects, unveiling impaired POLι recruitment and replication deceleration already under unperturbed conditions. Such an inhibitory effect on p53α was particularly pronounced in cells co-expressing Δ133p53α or Δ160p53α. Notably, this effect became evident after the expression of the isoforms in tumor cells, as well as after the knockdown of endogenous isoforms in human hematopoietic stem and progenitor cells. In summary, mimicking the situation found to be associated with many cancer types and stem cells, i.e., co-expression of alternative p53-isoforms with p53α, carved out interference with p53α functions in the p53-POLι-dependent DDT pathway.

Inhibition of Notch1 signaling reduces hepatocyte injury in nonalcoholic fatty liver disease via autophagy.

Nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease worldwide and an urgent target for clinical intervention. Notch1 signaling pathway activity was found to be related to the severity of NAFLD, but the specific mechanism is not precise. Here, we investigated the potential mechanisms of Notch1 signaling in the development of NAFLD. Firstly, we found that Notch1 signaling is activated in free fatty acids-treated HepG2 cells accompanied by lipid accumulation, apoptosis, oxidative stress, and mitochondrial damage, which could be alleviated by Notch1 inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). In the meantime, we found that administration of DAPT activated the autophagy pathway in NAFLD. Furthermore, the use of autophagy inhibitor chloroquine reversed the DAPT-mediated protective effect in NAFLD. All our results uncover a vital role of Notch1 in hepatocyte injury and metabolism of NAFLD, giving rise to a new sight for NAFLD treatment by regulation of Notch signaling and autophagy pathway.

Fgd5 is a Rac1-specific Rho GEF that is selectively inhibited by aurintricarboxylic acid.

Rho proteins are signalling molecules that control cellular dynamics, movement and morphological changes. They are activated by Rho guanine-nucleotide exchange factors (Rho GEFs) that transduce upstream signals into Rho-mediated activation of downstream processes. Fgd5 is a Rho GEF involved in angiogenesis and its target Rho protein for this process has been linked to Cdc42 activation. Here, we examined the function of purified Fgd5, specifically, which Rho proteins it activates and pinpoint the structural domains required for enzymatic activity. Using a GEF enzyme assay, we found that purified Fgd5 showed preferential activation of Rac1 and direct binding of Rac1 in pull-down and co-immunoprecipitation assays. Structural comparisons showed that the Fgd5 DH domain is highly similar to the Rac1 GEF, TrioN, supporting a role for Fgd5 as a Rac1 GEF. Compounds that bind to purified Fgd5 DH-PH protein were identified by screening a small molecule library via surface plasmon resonance. The effects of eleven ligands were further examined for their ability to inhibit the Fgd5 GEF enzymatic activity and Rac1 interaction. From these studies, we found that the compound aurintricarboxylic acid, and to a lesser extent mitoxantrone dihydrochloride, inhibited both Fgd5 GEF activation of Rac1 and their interaction. Aurintricarboxylic acid had no effect on the activity or binding of the Rac1 GEF, TrioN, thus demonstrating the feasibility of selectively disrupting Rho GEF activators. Abbreviations: a.a.: amino acid; ATA: aurintricarboxylic acid; DH: Dbl homology; DOCK: dictator of cytokinesis; Fgd: faciogenital dysplasia; GEF: guanine-nucleotide exchange factor; GST: glutathione S-transferase; LOPAC: library of pharmacologically active compounds; PH: pleckstrin homology; PDB: protein data bank; s.e.m.: standard error of the mean; SPR: surface plasmon resonance.

MicroRNA-137-3p Improves Nonalcoholic Fatty Liver Disease through Activating AMPKα.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide and can develop to nonalcoholic steatohepatitis and later hepatic cirrhosis with a high prevalence to hepatocellular carcinoma. Oxidative stress and chronic hepatic inflammation are implicated in the pathogenesis of NAFLD. MicroRNA-137-3p (miR-137-3p) are associated with oxidative stress and inflammation; however, its role and mechanism in NAFLD remain unclear. Mice were fed with a high-fat diet (HFD) for 24 weeks to establish the NAFLD model. To overexpress or suppress hepatic miR-137-3p expression, mice were intraperitoneally injected with the agomir, antagomir, or respective controls of miR-137-3p at a dose of 100 mg/kg weekly for 6 consecutive weeks before the mice were sacrificed. To validate the involvement of AMP-activated protein kinase alpha (AMPKα) or cAMP-specific phosphodiesterase 4D (PDE4D), HFD mice were intraperitoneally injected with 20 mg/kg compound C or 0.5 mg/kg rolipram every other day for 8 consecutive weeks before the mice were sacrificed. Hepatic miR-137-3p expression was significantly decreased in mice upon HFD stimulation. miR-137-3p agomir alleviated, while miR-137-3p antagomir facilitated HFD-induced oxidative stress, inflammation, and hepatic dysfunction in mice. Mechanistically, we revealed that miR-137-3p is directly bound to the 3'-untranslated region of PDE4D and subsequently increased hepatic cAMP level and protein kinase A activity, thereby activating the downstream AMPKα pathway. In summary, miR-137-3p improves NAFLD through activating AMPKα and it is a promising therapeutic candidate to treat NAFLD.

IRE1α-JNK pathway-mediated autophagy promotes cell survival in response to endoplasmic reticulum stress during the initial phase of hepatic steatosis.

AIMS: It has been widely reported that autophagy and inositol-requiring enzyme-1α (IRE1α)-c-Jun N-terminal kinase (JNK) pathway was involved in cell survival under endoplasmic reticulum (ER) stress, but their specific roles in hepatic steatosis remain unclear. This study aimed to determine the interaction between autophagy and IRE1α-JNK pathway on cell survival in response to ER stress during the initial phase of hepatic steatosis. METHODS: Hepatic steatosis was induced in HepG2 cells by supplementing oleic acid (OA). Lipid accumulation was evaluated by BODIPY493/503 staining. ER stress and IRE1α-JNK signaling were investigated by western blot. Autophagy was monitored by western blot, GFP-LC3 plasmid and immunofluorescence staining, while apoptosis was determined by western blotting, Annexin-V-FITC/PI staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. KEY FINDINGS: Aggravated lipid accumulation was found under increased ER stress during the initial phase of hepatic steatosis. Meanwhile, an increase of autophagy and no alteration of apoptosis were observed under increased ER stress. Interestingly, autophagy was induced by ER stress, while autophagy suppression led to an increase of apoptosis in response to ER stress Moreover, further study showed that IRE1α-JNK pathway was activated after ER stress and consequently induced autophagy, which promoted cell survival in the initial phase of hepatic steatosis. SIGNIFICANCE: We conclude that IRE1α-JNK pathway was activated during ER stress in the initial phase of hepatic steatosis and promoted cell survival by enhancing autophagy. Targeting IRE1α-JNK-autophagy signaling may provide new insight into preventive strategies for hepatic steatosis.

Association between PTGER4 polymorphisms and inflammatory bowel disease risk in Caucasian: A meta-analysis.

BACKGROUND: The results from previous studies on association between prostaglandin E receptor 4 (PTGER4) polymorphisms and inflammatory bowel disease (IBD) risk in Caucasian were conflict. The present study aimed to investigate the genetic association by conducting a meta-analysis. METHODS: Systematic literature search was conducted through Wiley Online Library, Chinese National Knowledge Infrastructure (CNKI), and PubMed databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to investigate the associations between rs4613763 T/C, 17234657T/G polymorphisms, and IBD risk in Caucasian. RESULTS: Twenty case-control studies consisting of 18,495 Crohn disease (CD) patients and 4203 ulcerative colitis (UC) patients, as well as 26,063 controls were included in this meta-analysis. The rs4613763T/C polymorphism had obvious influence on CD, UC risk in Caucasian. However, rs17234657T/G polymorphism had obvious influence on CD but not UC in Caucasian. CONCLUSION: This meta-analysis suggested that both the rs4613763 T/C, rs17234657T/G polymorphisms had obvious influence on risk of CD in Caucasian. In addition, rs4613763 T/C, polymorphism had obvious influence on risk of UC in Caucasian.

Ursodeoxycholic acid alleviates nonalcoholic fatty liver disease by inhibiting apoptosis and improving autophagy via activating AMPK.

Ursodeoxycholic acid (UDCA), first identified in bear bile, was widely used in cholestatic liver diseases. Our previous studies have suggested UDCA may exert favorable influence on hepatic steatosis. However, the molecular mechanism remains elusive. Given the role of autophagy and apoptosis dysregulation in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and pharmacological effects of UDCA on modulating autophagy, apoptosis. we sought to investigate whether UDCA had therapeutic effect on NAFLD and its mechanism of modulating autophagy, apoptosis. Our finding revealed that UDCA exerted obviously favorable influence on hepatic steatosis in NAFLD rats by activating AMP-activated protein kinase (AMPK). Mechanistic studies indicated UDCA inhibited apoptosis and improved autophagy by influencing Bcl-2/Beclin-1 and Bcl-2/Bax complex interaction. Importantly, above-mentioned influence of UDCA on autophagy, apoptosis and Bcl-2/Beclin-1, Bcl-2/Bax complex interaction in NAFLD were partly counteracted by AMPK inhibitor compound C(CC). In conclusion, UDCA exerts favorable influence on hepatic steatosis in NAFLD rats, which is attributable to apoptosis inhibition and autophagy induction by influencing Bcl-2/Beclin-1 complex and Bcl-2/Bax complex interaction via activating AMPK, indicating that UDCA may be a promising therapeutic target for NAFLD.

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter.

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the ROx (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%-150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%-50% enhancements in the areas around 35-40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.

Seasonal effects of additional HONO sources and the heterogeneous reactions of N2O5 on nitrate in the North China Plain.

We coupled the heterogeneous hydrolysis of N2O5 into the newly updated Weather Research and Forecasting model with Chemistry (WRF-Chem) to reveal the relative importance of the hydrolysis of N2O5 and additional nitrous acid (HONO) sources for the formation of nitrate during high PM2.5 events in the North China Plain (NCP) in four seasons. The results showed that additional HONO sources produced the largest nitrate concentrations in winter and negligible nitrates in summer, leading to a 10% enhancement of a PM2.5 peak in southern Beijing and a 15% enhancement in southeastern Hebei in winter. In contrast, the hydrolysis of N2O5 produced high nitrate in summer and low nitrate in winter, with the largest contribution of nearly 20% for a PM2.5 peak in southeastern Hebei in summer. During PM2.5 explosive growth events, the additional HONO sources played a key role in nitrate increases in southern Beijing and southwestern Hebei in winter, whereas the hydrolysis of N2O5 contributed the most to a rapid increase in nitrate in other seasons. HONO photolysis produced more hydroxyl radicals, which were >1.5 µg m-3 h-1 in the early explosive stage and led to a rapid nitrate increase at the southwestern Hebei sites in winter, while the heterogeneous reaction of N2O5 contributed greatly to a significant increase in nitrate in summer. The above results suggest that the additional HONO sources and the heterogeneous hydrolysis of N2O5 contributed the most to nitrate formation in NCP in winter and summer, respectively.