Dynamic interactions between E-cadherin and Ankyrin-G mediate epithelial cell polarity maintenance.

E-cadherin is an essential cell‒cell adhesion protein that mediates canonical cadherin-catenin complex formation in epithelial lateral membranes. Ankyrin-G (AnkG), a scaffold protein linking membrane proteins to the spectrin-based cytoskeleton, coordinates with E-cadherin to maintain epithelial cell polarity. However, the molecular mechanisms governing this complex formation and its relationships with the cadherin-catenin complex remain elusive. Here, we report that AnkG employs a promiscuous manner to encapsulate three discrete sites of E-cadherin by the same region, a dynamic mechanism that is distinct from the canonical 1:1 molar ratio previously described for other AnkG or E-cadherin-mediated complexes. Moreover, we demonstrate that AnkG-binding-deficient E-cadherin exhibited defective accumulation at the lateral membranes and show that disruption of interactions resulted in cell polarity malfunction. Finally, we demonstrate that E-cadherin is capable of simultaneously anchoring to AnkG and ß-catenin, providing mechanistic insights into the functional orchestration of the ankyrin-spectrin complex with the cadherin-catenin complex. Collectively, our results show that complex formation between E-cadherin and AnkG is dynamic, which enables the maintenance of epithelial cell polarity by ensuring faithful targeting of the adhesion molecule-scaffold protein complex, thus providing molecular mechanisms for essential E-cadherin-mediated complex assembly at cell‒cell junctions.

Genome-wide identification and skin expression of immunoglobulin superfamily in discus fish (Symphysodon aequifasciatus) reveal common genes associated with vertebrate lactation.

Discus Symphysodon spp. employs an unusual parental care behavior where fry feed on parental skin mucus after hatching. Studies on discus immunoglobulin superfamily (IgSF) especially during parental care are scarce. Here, a total of 518 IgSF members were identified based on discus genome and clustered into 12 groups, unevenly distributing on 30 linkage groups. A total of 92 pairs of tandem duplication and 40 pairs of segmental duplication that underwent purifying selection were identified. IgSF genes expressed differentially in discus skin during different care stages and between male and female parents. Specifically, the transcription of btn1a1, similar with mammalian lactation, increased after spawning, reached a peak when fry started biting on parents' skin mucus, and then decreased. The expression of btn2a1 and other immune members, e.g., nect4, fcl5 and cd22, were up-regulated when fry stopped biting on mucus. These results suggest the expression differentiation of IgSF genes in skin of discus fish during parental care.

Distinct skin morphological and transcriptomic profiles between wild and albino Oscar Astronotus ocellatus.

Oscar Astronotus ocellatus is an important ornamental fish, including albino and wild varieties. Albino individuals attract aquarium hobbyists due to their unique body color, but studies on the species' albinism mechanism are currently scarce. Here, we investigated the morphological and transcriptomic profiles of the skin of albino and wild Oscar. The results showed that the albino type had fewer oval-shaped melanophores and immature melanosomes but that the wild type contained more stellate-shaped melanophores and mature melanosomes. Albino Oscar had a degenerative pigment layer without obvious melanin deposition and content, while the wild type contained more concentrated melanin within the pigment layer. A total of 272,392 unigenes were detected, 109 of which were identified as differentially expressed genes (DEGs) between albino and wild Oscar. Pathways of DEGs, including those involved in complement and coagulation cascades, novobiocin biosynthesis, Th1 and Th2 cell differentiation, and tropane, piperidine and pyridine alkaloid biosynthesis, were significantly enriched. DEGs, including upregulated Sfrp5 and Tat, and downregulated Wnt-10a, Ppp3c, Notch1 and Trim27 involved in the Wnt signaling pathway, Notch signaling pathway, tyrosine metabolism, MAPK signaling pathway and melanogenesis, might be associated with the albinism of Oscar. This study characterized the difference in melanophore morphology between wild and albino Oscar and identified some albinism-related candidate genes and signaling pathways, helping to understand the genetic mechanism of fish albinism.

5-IP7 is a GPCR messenger mediating neural control of synaptotagmin-dependent insulin exocytosis and glucose homeostasis.

5-diphosphoinositol pentakisphosphate (5-IP7) is a signalling metabolite linked to various cellular processes. How extracellular stimuli elicit 5-IP7 signalling remains unclear. Here we show that 5-IP7 in ß cells mediates parasympathetic stimulation of synaptotagmin-7 (Syt7)-dependent insulin release. Mechanistically, vagal stimulation and activation of muscarinic acetylcholine receptors triggers Gαq-PLC-PKC-PKD-dependent signalling and activates IP6K1, the 5-IP7 synthase. Whereas both 5-IP7 and its precursor IP6 compete with PIP2 for binding to Syt7, Ca2+ selectively binds 5-IP7 with high affinity, freeing Syt7 to enable fusion of insulin-containing vesicles with the cell membrane. ß-cell-specific IP6K1 deletion diminishes insulin secretion and glucose clearance elicited by muscarinic stimulation, whereas mice carrying a phosphorylation-mimicking, hyperactive IP6K1 mutant display augmented insulin release, congenital hyperinsulinaemia and obesity. These phenotypes are absent in mice lacking Syt7. Our study proposes a new conceptual framework for inositol pyrophosphate physiology in which 5-IP7 acts as a GPCR second messenger at the interface between peripheral nervous system and metabolic organs, transmitting Gq-coupled GPCR stimulation to unclamp Syt7-dependent, and perhaps other, exocytotic events.

Crystal structure of the PDZ4 domain of MAGI2 in complex with PBM of ARMS reveals a canonical PDZ recognition mode.

Membrane-associated guanylate kinase, WW and PDZ domain-containing protein 2 (MAGI2) is a neuronal scaffold protein that plays critical roles at synaptic junctions by assembling neurotransmitter receptors and cell adhesion proteins through its multiple protein-protein interaction domains, including six PDZ domains, two phosphoserine-phosphothreonine binding WW domains, and a guanylate kinase GK domain. Previous studies showed that MAGI2 participates in formation of tetrameric complexes with PDZ-GEF1, TrkA receptor, and ankyrin repeat-rich membrane spanning (ARMS) protein at late endosomes and is crucial for neurite outgrowth. However, the molecular mechanism governing the assembly of these complexes remains unknown. Here, we characterize the direct interaction between MAGI2 and ARMS through multiple biochemical assays. Moreover, our solved crystal structure of the truncated PDZ4/PBM (PDZ binding motifs) complex of MAGI2 and ARMS proteins (MAGI2-PDZ4/ARMS-PBM) reveals that the binding interface lies between the αB/ßB groove from the PDZ4 of MAGI2 and the C-terminal PBM from ARMS. The structure reveals high similarity to others in this protein family where canonical PDZ/PBM interactions are observed. However, the conserved "GLGF" motif in the PSD-95-PDZ3 changes to "GFGF" in the MAGI2-PDZ4/ARMS-PBM complex. We further validated our crystal structure through serial mutagenesis assays. Taken together, our study provides the biochemical details and binding mechanisms that underpin the stabilization of the MAGI2-PDZ4/ARMS-PBM complex, thereby offering a biochemical and structural basis for further understanding of the functional roles of MAGI2, ARMS, PDZ-GEF1, and TrkA in forming the tetrameric receptor complex in neuronal signaling.

Exposure to microplastics impairs digestive performance, stimulates immune response and induces microbiota dysbiosis in the gut of juvenile guppy (Poecilia reticulata).

Microplastics (MPs) are widely distributing in aquatic environment. They are easily ingested by aquatic organisms and accumulate in digestive tract especially of intestine. To explore the potential effects of MPs on intestine, here we, using juvenile guppy (Poecilia reticulata) as experimental animal, investigated the response characteristics of digestion, immunity and gut microbiota. After exposure to 100 and 1000 µg/L concentrations of MPs (polystyrene; 32-40 µm diameters) for 28 days, we observed that MPs could exist in guppy gut and induce enlargement of goblet cells. Activities of digestive enzymes (trypsin, chymotrypsin, amylase and lipase) in guppy gut generally reduced. MPs stimulated the expression of immune cytokines (TNF-α, IFN-γ, TLR4 and IL-6). Through high throughput sequencing of 16S rRNA gene, decreases in diversity and evenness and changed composition of microbiota were found in guppy gut. PICRUSt analysis revealed that MPs might have effects on intestinal microbiota functions, such as inhibition of metabolism and repair pathway. Our findings suggested that MPs could retain in the gut of juvenile guppy, impair digestive performance, stimulate immune response and induce microbiota dysbiosis in guppy gut. The results obtained here provide new insights into the potential risks of MPs to aquatic animals.

Terminating pre-ozonation prior to biological activated carbon filtration results in increased formation of nitrogenous disinfection by-products upon subsequent chlorination.

Previous research demonstrated that ozone dosed before biological activated carbon (BAC) filtration reduces the formation of disinfection by-products (DBPs) upon subsequent chlorination. The current work aimed to evaluate the impact of terminating this pre-ozonation on the ability of the BAC to remove the precursors of N-DBPs. More N-DBP precursors passed into the post-BAC water when the pre-ozonation was terminated, resulting in greater formation of N-DBPs when the water was subsequently chlorinated, compared to a parallel BAC filter when the pre-ozonation was run continuously. Moreover, the N-DBP formation potential was significantly increased in the effluent of the BAC filter after terminating pre-ozonation, compared with the influent of the BAC filter (i.e. the effluent from the sand filter). Therefore, while selectively switching pre-ozonation on/off may have cost and other operational benefits for water suppliers, these should be weighed against the increased formation of N-DBPs and potential associated health risks.

The effects of ambient temperature on cerebrovascular mortality: an epidemiologic study in four climatic zones in China.

BACKGROUND: Little evidence is available about the association between temperature and cerebrovascular mortality in China. This study aims to examine the effects of ambient temperature on cerebrovascular mortality in different climatic zones in China. METHOD: We obtained daily data on weather conditions, air pollution and cerebrovascular deaths from five cities (Beijing, Tianjin, Shanghai, Wuhan, and Guangzhou) in China during 2004-2008. We examined city-specific associations between ambient temperature and the cerebrovascular mortality, while adjusting for season, long-term trends, day of the week, relative humidity and air pollution. We examined cold effects using a 1°C decrease in temperature below a city-specific threshold, and hot effects using a 1°C increase in temperature above a city-specific threshold. We used a meta-analysis to summarize the cold and hot effects across the five cities. RESULTS: Beijing and Tianjin (with low mean temperature) had lower thresholds than Shanghai, Wuhan and Guangzhou (with high mean temperature). In Beijing, Tianjin, Wuhan and Guangzhou cold effects were delayed, while in Shanghai there was no or short induction. Hot effects were acute in all five cities. The cold effects lasted longer than hot effects. The hot effects were followed by mortality displacement. The pooled relative risk associated with a 1°C decrease in temperature below thresholds (cold effect) was 1.037 (95% confidence interval (CI): 1.020, 1.053). The pooled relative risk associated with a 1°C increase in temperature above thresholds (hot effect) was 1.014 (95% CI: 0.979, 1.050). CONCLUSION: Cold temperatures are significantly associated with cerebrovascular mortality in China, while hot effect is not significant. People in colder climate cities were sensitive to hot temperatures, while people in warmer climate cities were vulnerable to cold temperature.

[Health damage assessment due to PM2.5 exposure during haze pollution events in Beijing-Tianjin-Hebei region in January 2013].

OBJECTIVE: To assess the human health damage due to particulate matter ≤ 2.5 µm (PM2.5) exposure during the haze pollution events in 12 cities of Beijing-Tianjin-Hebei region in January 2013. METHODS: The data were collected for urban population, ambient air quality, baseline mortality rate and emergency visits in Beijing, Tianjin, Shijiazhuang, Baoding, Chengde, Handan, Langfang, Hengshui, Qinhuangdao, Tangshan, Xingtai and Zhangjiakou. Then the exposure-response relationship was constructed between short-term PM2.5 exposure and mortality and emergency room visits with meta-analysis. Thus the excess deaths and emergency room visits due to PM2.5 exposure were estimated during the haze pollution events using city-specific exposure population, PM2.5 daily concentration and exposure-response coefficients. RESULTS: Three serious PM2.5 pollution events occurred on January 12, January 19 and January 27 in Beijing-Tianjin-Hebei region respectively. From January 10 to January 31, the 24 h mean concentrations of PM2.5 in Beijing, Tianjin, Shijiazhuang, Tangshan, Qinhuangdao, Handan, Xingtai, Baoding, Zhangjiakou, Chengde, Langfang, Hengshui were 705, 411, 675, 506, 255, 598, 698, 667, 231, 178, 718 and 405 µg/m(3). Xingtai, Shijiazhuang, Handan, Baoding, Langfang and Beijing were the more polluted areas. And there were 17 days (77.3%), 13 days (59.1%), 12 days (54.5%), 11 days (50.0%), 10 days (45.5%) and 8 days (36.4%) of Air Quality Index reaching the serious level respectively. The short-term PM2.5 exposure caused 2725 excess death including 846 excess deaths duo to respiratory disease and 1878 excess deaths due to circulatory disease in Beijing-Tianjin-Hebei region from January 10 to January 31. CONCLUSIONS: The haze pollution events led to serious public health damage. And it is imperative to take actions of controlling PM2.5 pollution.

Extremely cold and hot temperatures increase the risk of ischaemic heart disease mortality: epidemiological evidence from China.

OBJECTIVE: To examine the effects of extremely cold and hot temperatures on ischaemic heart disease (IHD) mortality in five cities (Beijing, Tianjin, Shanghai, Wuhan and Guangzhou) in China; and to examine the time relationships between cold and hot temperatures and IHD mortality for each city. DESIGN: A negative binomial regression model combined with a distributed lag non-linear model was used to examine city-specific temperature effects on IHD mortality up to 20 lag days. A meta-analysis was used to pool the cold effects and hot effects across the five cities. PATIENTS: 16 559 IHD deaths were monitored by a sentinel surveillance system in five cities during 2004-2008. RESULTS: The relationships between temperature and IHD mortality were non-linear in all five cities. The minimum-mortality temperatures in northern cities were lower than in southern cities. In Beijing, Tianjin and Guangzhou, the effects of extremely cold temperatures were delayed, while Shanghai and Wuhan had immediate cold effects. The effects of extremely hot temperatures appeared immediately in all the cities except Wuhan. Meta-analysis showed that IHD mortality increased 48% at the 1st percentile of temperature (extremely cold temperature) compared with the 10th percentile, while IHD mortality increased 18% at the 99th percentile of temperature (extremely hot temperature) compared with the 90th percentile. CONCLUSIONS: Results indicate that both extremely cold and hot temperatures increase IHD mortality in China. Each city has its characteristics of heat effects on IHD mortality. The policy for response to climate change should consider local climate-IHD mortality relationships.

Time-series analysis of the relationship between air quality, temperature, and sudden unexplained death in Beijing during 2005 - 2008.

BACKGROUND: There is a yearly increase in the rate of sudden unexplained death (SUD), even through extensive physical examination and the testing of a large number of biomarkers, the cause of sudden death in patients previously in good health cannot be fully determined. During clinical practice, a spatial aggregation phenomenon has been observed in the incidence of sudden unexplained death. Previous research has shown that environmental factors, such as air pollution, weather conditions, etc., have a significant impact on human health. In the wake of the continuous environmental damage, the relationship between environmental factors and sudden unexplained death still needs to be studied. To study the relationship between sudden unexplained death and air quality and temperature, commonly used markers such as particulate matter of aerodynamic diameter < 10 µm (PM(10)), daily average concentration of the gaseous pollutants sulfur dioxide (SO2) and nitrogen dioxide (NO2), and the daily average temperature were investigated. METHODS: The methods include collecting the data of sudden unexplained death; air quality monitoring; meteorological monitoring from January 1, 2005 to December 31, 2008; utilizing generalized additive models (GAM); controlling the influential factors such as secular trend, seasonal trend, and Sunday dummy variable; and analyzing the correlation between daily inhalable particle concentration, daily average temperature, and the number of daily SUD. RESULTS: There was no statistical significance between the daily inhalable particle and daily incidence of sudden unexplained death. Incidence rate of sudden unexplained death had nonlinear positive correlation with daily temperature. When the temperature was 5°C above the daily average temperature, the daily incidence of sudden unexplained death went up with the rising temperature. CONCLUSION: Temperature may be one of the key risk factor or precipitating factor of SUD.

[Time-series analysis on the association between gaseous air pollutants and daily mortality in urban residents in Tianjin].

OBJECTIVE: To study the association between sulphur dioxide, nitrogen dioxide and daily mortality in urban population from Tianjin. METHODS: Data on daily concentration of inhalable particulate matter, sulphur dioxide and nitrogen dioxide, daily mean temperature and relative humidity, daily cause-specific death counts were collected. Generalized additive models was used to explore the relationship between sulphur dioxide, nitrogen dioxide and daily mortality, after adjusting the effects of long-term and seasonal trend, weather conditions, and to analyze the potential effect of particulate matter and model parameters on relative risk estimates. RESULTS: Results showed that the daily concentrations of SO(2) and NO(2) were significantly associated with daily non-accidental and cardiovascular mortality but not associated with daily respiratory mortality. An increase of 10 µg/m(3) in SO(2) was associated with 0.56% (95%CI: 0.23% - 0.89%) non-accidental morality, 0.49% (0.06% - 0.93%) cardiovascular morality, respectively. An increase of 10 µg/m(3) in NO(2) was associated with 0.94% (95%CI: 0.17% - 1.70%) non-accidental morality, 1.29% (0.29% - 2.30%) cardiovascular morality, respectively. CONCLUSION: Our findings suggested that exposure to SO(2) and NO(2) was significantly associated with daily cardiovascular and respiratory mortality in urban population in Tianjin.

[Time-series analysis of association between inhalable particulate matter and daily mortality among urban residents in Tianjin].

OBJECTIVE: To study the association between particulate matter less than 10 micron in aerodynamic diameter (PM(10)) and daily mortality among urban population in Tianjin. METHODS: We collected data of air quality, daily mean temperature and relative humidity, and daily cause-specific death counts, and used generalized additive models to explore the relationship between ambient particulate matter and daily mortality, after adjusting the effects of long-term and seasonal trend, weather conditions and other gaseous pollutants, such as sulfur dioxide and nitrogen dioxide. RESULTS: An increase of 10 µg/m(3) in PM(10) was associated with 0.45% (95%CI: 0.21 - 0.69) non-accidental morality, 0.60% (0.29 - 0.91) circulatory morality and 0.82% (0.04 - 1.61) respiratory morality, respectively. CONCLUSION: Our findings indicated that the extent of exposure to PM(10) was significantly associated with daily mortality in urban population in Tianjin, especially with the mortality rates on circulatory and respiratory diseases.

The short-term effect of air pollution on cardiovascular mortality in Tianjin, China: comparison of time series and case-crossover analyses.

BACKGROUND: Many studies have illustrated that ambient air pollution negatively impacts on health. However, little evidence is available for the effects of air pollution on cardiovascular mortality (CVM) in Tianjin, China. Also, no study has examined which strata length for the time-stratified case-crossover analysis gives estimates that most closely match the estimates from time series analysis. OBJECTIVES: The purpose of this study was to estimate the effects of air pollutants on CVM in Tianjin, China, and compare time-stratified case-crossover and time series analyses. METHOD: A time-stratified case-crossover and generalized additive model (time series) were applied to examine the impact of air pollution on CVM from 2005 to 2007. Four time-stratified case-crossover analyses were used by varying the stratum length (Calendar month, 28, 21 or 14 days). Jackknifing was used to compare the methods. Residual analysis was used to check whether the models fitted well. RESULTS: Both case-crossover and time series analyses show that air pollutants (PM(10), SO(2) and NO(2)) were positively associated with CVM. The estimates from the time-stratified case-crossover varied greatly with changing strata length. The estimates from the time series analyses varied slightly with changing degrees of freedom per year for time. The residuals from the time series analyses had less autocorrelation than those from the case-crossover analyses indicating a better fit. CONCLUSION: Air pollution was associated with an increased risk of CVM in Tianjin, China. Time series analyses performed better than the time-stratified case-crossover analyses in terms of residual checking.

Gaseous air pollution and emergency hospital visits for hypertension in Beijing, China: a time-stratified case-crossover study.

BACKGROUND: A number of epidemiological studies have been conducted to research the adverse effects of air pollution on mortality and morbidity. Hypertension is the most important risk factor for cardiovascular mortality. However, few previous studies have examined the relationship between gaseous air pollution and morbidity for hypertension. METHODS: Daily data on emergency hospital visits (EHVs) for hypertension were collected from the Peking University Third Hospital. Daily data on gaseous air pollutants (sulfur dioxide (SO2) and nitrogen dioxide (NO2)) and particulate matter less than 10 µm in aerodynamic diameter (PM10) were collected from the Beijing Municipal Environmental Monitoring Center. A time-stratified case-crossover design was conducted to evaluate the relationship between urban gaseous air pollution and EHVs for hypertension. Temperature and relative humidity were controlled for. RESULTS: In the single air pollutant models, a 10 µg/m3 increase in SO2 and NO2 were significantly associated with EHVs for hypertension. The odds ratios (ORs) were 1.037 (95% confidence interval (CI): 1.004-1.071) for SO2 at lag 0 day, and 1.101 (95% CI: 1.038-1.168) for NO2 at lag 3 day. After controlling for PM10, the ORs associated with SO2 and NO2 were 1.025 (95% CI: 0.987-1.065) and 1.114 (95% CI: 1.037-1.195), respectively. CONCLUSION: Elevated urban gaseous air pollution was associated with increased EHVs for hypertension in Beijing, China.

The relationship between particulate air pollution and emergency hospital visits for hypertension in Beijing, China.

BACKGROUND: A number of epidemiological studies have examined the adverse effect of air pollution on mortality and morbidity. Also, several studies have investigated the associations between air pollution and specific-cause diseases including arrhythmia, myocardial infarction, and heart failure. However, little is known about the relationship between air pollution and the onset of hypertension. OBJECTIVE: To explore the risk effect of particulate matter air pollution on the emergency hospital visits (EHVs) for hypertension in Beijing, China. METHODS: We gathered data on daily EHVs for hypertension, fine particulate matter less than 2.5 microm in aerodynamic diameter (PM(2.5)), particulate matter less than 10 microm in aerodynamic diameter (PM(10)), sulfur dioxide, and nitrogen dioxide in Beijing, China during 2007. A time-stratified case-crossover design with distributed lag model was used to evaluate associations between ambient air pollutants and hypertension. Daily mean temperature and relative humidity were controlled in all models. RESULTS: There were 1,491 EHVs for hypertension during the study period. In single pollutant models, an increase in 10 microg/m(3) in PM(2.5) and PM(10) was associated with EHVs for hypertension with odds ratios (overall effect of five days) of 1.084 (95% confidence interval (CI): 1.028, 1.139) and 1.060% (95% CI: 1.020, 1.101), respectively. CONCLUSION: Elevated levels of ambient particulate matters are associated with an increase in EHVs for hypertension in Beijing, China.