乙酰肝素酶和CD105在大肠癌中的表达及其相关性

目的探讨乙酰肝素酶和CD105在大肠癌中的表达以及它们之间的关系。方法应用原位杂交方法检测乙酰肝素酶mRNA在95例大肠癌组织中的定位及表达;并用免疫组化方法对全部标本进行CD105染色,记数肿瘤微血管密度(microvesseldensity,MVD);分析乙酰肝素酶mRNA表达与大肠癌浸润、转移和血管生成之间的关系。结果95例大肠癌组织中,乙酰肝素酶mRNA阳性表达49例(51.57%),MVD平均值为(72.1±20.6);阴性表达46例(48.42%),MVD平均值为(41.3±12.4),乙酰肝素酶阳性组MVD表达与阴性组相比有显著性差异(P<0.01)。有浆膜浸润和伴淋巴结转移的大肠癌组织中,乙酰肝素酶mRNA表达阳性率分别为61.42%、63.49%,高于无浆膜浸润(24.00%)和无淋巴结转移组(28.12%),有显著差异(P<0.01)。结论乙酰肝素酶可促进大肠癌的浸润、转移和血管生成,可作为反映大肠癌生物学行为的客观指标。     

ZC3H13 suppresses colorectal cancer proliferation and invasion via inactivating Ras–ERK signaling

ZC3H13 is a canonical CCCH zinc finger protein, which harbors a somatic frame-shift mutation in colorectal cancer (CRC). However, its expression and biological function were still uncertain. In the current study, we found that ZC3H13 was served as a tumor suppressor in CRC cells, which decreased the expression of Snail, Cyclin D1, and Cyclin E1, and increased the expression of Occludin and Zo-1 through inactivating Ras–ERK signaling pathway. Furthermore, reduction of ZC3H13 associated with advanced TNM stage (p = 0.02), positive regional lymph node metastasis ( p = 0.01). Taken together, the current study indicated that ZC3H13 may be an upstream regulator of Ras–ERK signaling pathway and suppressed invasion and proliferation of CRC.     

Contribution of autophagy-related gene 5 variants to acquired aplastic anemia in Han-Chinese population

Immune-mediated quantitative and qualitative defects of hematopoietic stem/progenitor cells (HSPCs) play a vital role in the pathophysiology of acquired aplastic anemia (AA). Autophagy is closely related to T cell pathophysiology and the destiny of HSPCs, in which autophagy-related gene 5 (ATG5) is indispensably involved. We hypothesized that genetic variants of ATG5 might contribute to AA. We studied six ATG5 polymorphisms in a Chinese cohort of 176 patients with AA to compare with 157 healthy controls. A markedly decreased risk of AA in the recessive models of rs510432 and rs803360 polymorphisms (adjusted odds ratio [OR], 95% confidence interval [CI] = 0.467 [0.236-0.924], P = 0.029 for ATG5 rs510432; adjusted OR [95% CI] = 0.499 [0.255-0.975], P = 0.042 for ATG5 rs803360) was observed. Furthermore, the decreased risk was even more pronounced among nonsevere AA compared with healthy controls under recessive models (adjusted OR [95% CI] = 0.356 [0.141-0.901], P = 0.029 for ATG5 rs510432; adjusted OR [95% CI] = 0.348 [0.138-0.878], P = 0.025 for ATG5 rs803360; adjusted OR [95% CI] = 0.352 [0.139-0.891], P = 0.027 for ATG5 rs473543). Above all, rs573775 can strongly predict the occurrence of newly onset hematological event in patients with AA. Our results indicate that genetic ATG5 variants contributed to AA, which may facilitate further clarifying the underlying mechanisms of AA and making a patient-tailored medical decision.     

Response of Bacterioplankton Communities to Cadmium Exposure in Coastal Water Microcosms with High Temporal Variability

Multiple anthropogenic disturbances to bacterial diversity have been investigated in coastal ecosystems, in which temporal variability in the bacterioplankton community has been considered a ubiquitous process. However, far less is known about the temporal dynamics of a bacterioplankton community responding to pollution disturbances such as toxic metals. We used coastal water microcosms perturbed with 0, 10, 100, and 1,000 μg liter⁻¹ of cadmium (Cd) for 2 weeks to investigate temporal variability, Cd-induced patterns, and their interaction in the coastal bacterioplankton community and to reveal whether the bacterial community structure would reflect the Cd gradient in a temporally varying system. Our results showed that the bacterioplankton community structure shifted along the Cd gradient consistently after a 4-day incubation, although it exhibited some resistance to Cd at low concentration (10 μg liter⁻¹). A process akin to an arms race between temporal variability and Cd exposure was observed, and the temporal variability overwhelmed Cd-induced patterns in the bacterial community. The temporal succession of the bacterial community was correlated with pH, dissolved oxygen, NO₃⁻-N, NO₂⁻-N, PO₄³⁻-P, dissolved organic carbon, and chlorophyll a, and each of these parameters contributed more to community variance than Cd did. However, elevated Cd levels did decrease the temporal turnover rate of community. Furthermore, key taxa, affiliated to the families Flavobacteriaceae, Rhodobacteraceae, Erythrobacteraceae, Piscirickettsiaceae, and Alteromonadaceae, showed a high frequency of being associated with Cd levels during 2 weeks. This study provides direct evidence that specific Cd-induced patterns in bacterioplankton communities exist in highly varying manipulated coastal systems. Future investigations on an ecosystem scale across longer temporal scales are needed to validate the observed pattern.     

Exocyst-Positive Organelles and Autophagosomes Are Distinct Organelles in Plants

Autophagosomes are organelles that deliver cytosolic proteins for degradation in the vacuole of the cell. In contrast, exocyst-positive organelles (EXPO) deliver cytosolic proteins to the cell surface and therefore represent a form of unconventional protein secretion. Because both structures have two boundary membranes, it has been suggested that they may have been falsely treated as separate entities. Using suspension culture cells and root tissue cells of transgenic Arabidopsis (Arabidopsis thaliana) plants expressing either the EXPO marker Arabidopsis Exo70E2-GFP or the autophagosome marker yellow fluorescent protein (YFP)-autophagy-related gene 8e/f (ATG8e/f), and using specific antibodies against Exo70E2 and ATG8, we have now established that, in normally growing cells, EXPO and autophagosomes are distinct from one another. However, when cells/roots are subjected to autophagy induction, EXPO as well as autophagosomes fuse with the vacuole. In the presence of concanamycin A, the punctate fluorescent signals from both organelles inside the vacuole remain visible for hours and overlap to a significant degree. Tonoplast staining with FM4-64/YFP-Rab7-like GTPase/YFP-vesicle-associated membrane protein711 confirmed the internalization of tonoplast membrane concomitant with the sequestration of EXPO and autophagosomes. This suggests that EXPO and autophagosomes may be related to one another; however, whereas induction of autophagy led to an increase in the amount of ATG8 recruited to membranes, Exo70E2 did not respond in a similar manner.Protein transport between intracellular organelles and the plasma membrane (PM) is mediated by vesicles (Park and Jürgens, 2011; Brandizzi and Barlowe, 2013). However, successful protein trafficking is not only a question of selective sorting and packaging of cargo molecules into vesicles (Schu, 2001; Sato and Nakano, 2007), but is also the result of correct targeting, capture, and recognition by the acceptor membranes (Sztul and Lupashin, 2006). Two types of protein complexes serve this purpose: long-range tethering factors (Yu and Hughson, 2010) and cognate v- and t-soluble NSF attachment protein receptors (SNAREs; Jahn and Scheller, 2006). Many of the tethering factors are multisubunit protein complexes, probably the most well-known example being the exocyst. This is an octameric complex containing the proteins Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70, and Exo84, and was originally described in yeast (Saccharomyces cerevisiae) as a complex mediating the fusion of secretory vesicles with the PM (TerBush et al., 1996). In the meantime, it is now recognized as being ubiquitously required for exocytic events in all eukaryotic cells (Heider and Munson, 2012). The exocyst complex also facilitates a number of other membrane fusion processes such as cytokinesis (Neto and Gould, 2011; Rybak et al., 2014) and autophagy (Bodemann et al., 2011). Plants also have an exocyst complex, and there are a number of papers implicating its role in secretion (Kulich et al., 2010; Li et al., 2013; Safavian and Goring, 2013; Cole et al., 2014). An interesting feature of the plant exocyst complex is the amplification of some of its subunits, in particular Exo70, which in Arabidopsis (Arabidopsis thaliana) has 23 paralogs (Synek et al., 2006). This has led to the suggestion that plants may have multiple exocyst complexes (Cvrčková et al., 2012). Indeed, whereas an Exo70A1-type exocyst is required for conventional secretory processes (Hála et al., 2008; Zárský et al., 2009), an Exo70E2-type exocyst appears to be characteristic for unconventional protein secretion (Wang et al., 2010; Ding et al., 2012, 2014a, 2014b). Furthermore, Exo70B1 seems to be specifically needed for the fusion of autophagosomes with the vacuole (Kulich et al., 2013).The Exo70E2-positive structures, termed exocyst-positive organelles (EXPO), in plants are 500 to 800 nm in diameter and have two boundary membranes (Wang et al., 2010; Ding et al., 2014b). As such, they are morphologically indistinguishable from autophagosomes, both in animals (Yang and Klionsky, 2010) and in plants (Zhuang et al., 2013). Unlike autophagosomes, which ultimately fuse with the lytic compartment of the cell (lysosome or vacuole), EXPO deliver the luminal contents into the apoplast first by fusion of the outer membrane with the PM, then by degradation of the inner boundary membrane (Wang et al., 2010; Ding et al., 2012). The authenticity of EXPO has been challenged by Kulich et al. (2013), who have claimed that “overexpression of exocyst subunits itself may cause stimulation of biogenesis of new exocyst positive compartments that are normally absent.” Although it cannot be ruled out that overexpression of Exo70E2 may result in an increase in EXPO numbers, indeed overexpression of Arabidopsis Exo70E2 (AtExo70E2) in mammalian cells causes EXPO-like structures to be formed (Ding et al., 2014b), and similar EXPO densities are obtained in Arabidopsis protoplasts when the expression is driven by the Exo70E2 native promoter (Ding et al., 2014b). More importantly, EXPO can be immunologically detected in wild-type cells with Exo70E2 antibodies (Wang et al., 2010). Nevertheless, the structural similarity between EXPO and autophagosomes suggests that they might in some way be related or follow the same biogenetic route in the cell.In this paper, we describe the fate of EXPO in suspension-cultured cells of Arabidopsis as well as in Arabidopsis root cells after the induction of autophagy. Visualization of EXPO and autophagosomes was done in cells expressing fluorescent AtExo70E2 or Arabidopsis autophagy-related gene8 (AtATG8), a well-known autophagosome marker, or both, as well as immunologically with specific antibodies against Exo70E2 and ATG8. In untreated cells, it is clear that EXPO and autophagosomes are separate and distinct organelles. However, after induction of autophagy in the presence of concanamycin A (ConcA), EXPO signals are lost from the PM and instead are gradually detected, together with AtATG8 signals, in the vacuole lumen. These signals partially overlap with FM4-64, which was used to stain the tonoplast. This points to an internalization of tonoplast membrane concomitant with the sequestration of EXPO and autophagosomes. Although autophagy caused an increase in the amount of ATG8 recruited to membranes, a similar effect was not observed with AtExo70E2.     

Biogeography of the Sediment Bacterial Community Responds to a Nitrogen Pollution Gradient in the East China Sea

Patterns of microbial distribution represent the integrated effects of historical and biological processes and are thus a central issue in ecology. However, there is still active debate on whether dispersal limitation contributes to microbial diversification in strongly connected systems. In this study, sediment samples were collected along a transect representing a variety of seawater pollution levels in the East China Sea. We investigated whether changes in sediment bacterial community structures would indicate the effects of the pollution gradient and of dispersal limitation. Our results showed consistent shifts in bacterial communities in response to pollution. More geographically distant sites had more dissimilar communities (r = −0.886, P < 0.001) in this strongly connected sediment ecosystem. A variance analysis based on partitioning by principal coordinates of neighbor matrices (PCNM) showed that spatial distance (dispersal limitation) contributed more to bacterial community variation (8.2%) than any other factor, although the environmental factors explained more variance when combined (11.2%). In addition, potential indicator taxa (primarily affiliated with Deltaproteobacteria and Gammaproteobacteria) were identified; these taxa characterized the pollution gradient. This study provides direct evidence that dispersal limitation exists in a strongly connected marine sediment ecosystem and that candidate indicator taxa can be applied to evaluate coastal pollution levels.     

The application of bacterial indicator phylotypes to predict shrimp health status

The incidence of shrimp disease is closely associated with the microbial composition in surrounding water, but it remains uncertain whether microbial indicator phylotypes are predictive for shrimp health status (healthy or diseased). To test this idea, we combined the data from our previous works, to investigate the feasibility of indicator phylotypes as independent variables to predict the health status during a shrimp culture procedure. The results showed linearly increased dissimilarities (P?79 %). Overall, this study provides solid evidences that indicator phylotypes could be served as independent variables for predicting the incidences of shrimp disease.     

How Vacuolar Sorting Receptor Proteins Interact with Their Cargo Proteins: Crystal Structures of Apo and Cargo-Bound Forms of the Protease-Associated Domain from an Arabidopsis Vacuolar Sorting Receptor

In plant cells, soluble proteins are directed to vacuoles because they contain vacuolar sorting determinants (VSDs) that are recognized by vacuolar sorting receptors (VSR). To understand how a VSR recognizes its cargo, we present the crystal structures of the protease-associated domain of VSR isoform 1 from Arabidopsis thaliana (VSR1PA) alone and complexed with a cognate peptide containing the barley (Hordeum vulgare) aleurain VSD sequence of ₁ADSNPIRPVT₁₀. The crystal structures show that VSR1PA binds the sequence, Ala-Asp-Ser, preceding the NPIR motif. A conserved cargo binding loop, with a consensus sequence of ₉₅RGxCxF₁₀₀, forms a cradle that accommodates the cargo-peptide. In particular, Arg-95 forms a hydrogen bond to the Ser-3 position of the VSD, and the essential role of Arg-95 and Ser-3 in receptor-cargo interaction was supported by a mutagenesis study. Cargo binding induces conformational changes that are propagated from the cargo binding loop to the C terminus via conserved residues in switch I-IV regions. The resulting 180° swivel motion of the C-terminal tail is stabilized by a hydrogen bond between Glu-24 and His-181. A mutagenesis study showed that these two residues are essential for cargo interaction and trafficking. Based on our structural and functional studies, we present a model of how VSRs recognize their cargos.