E3 ubiquitin ligase tripartite motif 38 negatively regulates TLR-mediated immune responses by proteasomal degradation of TNF receptor-associated factor 6 in macrophages

Activation of TLR signaling in the innate immune cells is critical for the elimination of invading microorganisms. However, uncontrolled activation may lead to autoimmune and inflammatory diseases. In this article, we report the identification of tripartite motif (TRIM) 38 as a negative feedback regulator in TLR signaling by targeting TNFR-associated factor 6 (TRAF6). TRIM38 was induced by TLR stimulation in an NF-κB-dependent manner in macrophages. Knockdown of TRIM38 expression by small interfering RNA resulted in augmented activation of NF-κB and MAPKs, and enhanced expression of proinflammatory cytokines, whereas overexpression of TRIM38 has an opposite effect. As an E3 ligase, TRIM38 bound to TRAF6 and promoted K48-linked polyubiquitination, which led to the proteasomal degradation of TRAF6. Consistently, knockdown of TRIM38 expression resulted in higher protein level of TRAF6 in primary macrophages. Our findings defined a novel function for TRIM38 to prevent excessive TLR-induced inflammatory responses through proteasomal degradation of TRAF6.     

Hepatic overexpression of methionine sulfoxide reductase A reduces atherosclerosis in apolipoprotein E-deficient mice

Methionine sulfoxide reductase A (MsrA), a specific enzyme that converts methionine-S-sulfoxide to methionine, plays an important role in the regulation of protein function and the maintenance of redox homeostasis. In this study, we examined the impact of hepatic MsrA overexpression on lipid metabolism and atherosclerosis in apoE-deficient (apoE^−/−) mice. In vitro study showed that in HepG2 cells, lentivirus-mediated human MsrA (hMsrA) overexpression upregulated the expression levels of several key lipoprotein-metabolism-related genes such as liver X receptor α, scavenger receptor class B type I, and ABCA1. ApoE^−/− mice were intravenously injected with lentivirus to achieve high-level hMsrA expression predominantly in the liver. We found that hepatic hMsrA expression significantly reduced plasma VLDL/LDL levels, improved plasma superoxide dismutase, and paraoxonase-1 activities, and decreased plasma serum amyloid A level in apoE^−/− mice fed a Western diet, by significantly altering the expression of several genes in the liver involving cholesterol selective uptake, conversion and excretion into bile, TG biosynthesis, and inflammation. Moreover, overexpression of hMsrA resulted in reduced hepatic steatosis and aortic atherosclerosis. These results suggest that hepatic MsrA may be an effective therapeutic target for ameliorating dyslipidemia and reducing atherosclerosis-related cardiovascular diseases.     

The complete mitochondrial genome and phylogenetic analysis of the giant panda (Ailuropoda melanoleuca)

The complete mitochondrial genome sequence of the giant panda, Ailuropoda melanoleuca, was determined by the long and accurate polymerase chain reaction (LA-PCR) with conserved primers and primer walking sequence methods. The complete mitochondrial DNA is 16,805 nucleotides in length and contains two ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes and one control region. The total length of the 13 protein-coding genes is longer than the American black bear, brown bear and polar bear by 3 amino acids at the end of ND5 gene. The codon usage also followed the typical vertebrate pattern except for an unusual ATT start codon, which initiates the NADH dehydrogenase subunit 5 (ND5) gene. The molecular phylogenetic analysis was performed on the sequences of 12 concatenated heavy-strand encoded protein-coding genes, and suggested that the giant panda is most closely related to bears.     

S-1-Based versus Capecitabine-Based Preoperative Chemoradiotherapy in the Treatment of Locally Advanced Rectal Cancer: A Matched-Pair Analysis

Objective

The aim of this paper was to compare the efficacy and safety of S-1-based and capecitabine-based preoperative chemoradiotherapy regimens in patients with locally advanced rectal cancer through a retrospective matched-pair analysis.

Materials and methods

Between Jan 2010 and Mar 2014, 24 patients with locally advanced rectal cancer who received preoperative radiotherapy concurrently with S-1 were individually matched with 24 contemporary patients with locally advanced rectal cancer who received preoperative radiotherapy concurrently with capecitabine according to clinical stage (as determined by pelvic magnetic resonance imaging and computed tomography) and age (within five years). All these patients performed mesorectal excision 4–8 weeks after the completion of chemoradiotherapy.

Results

The tumor volume reduction rates were 55.9±15.1% in the S-1 group and 53.8±16.0% in the capecitabine group (p = 0.619). The overall downstaging, including both T downstaging and N downstaging, occurred in 83.3% of the S-1 group and 70.8% of the capecitabine group (p = 0.508). The significant tumor regression, including regression grade I and II, occurred in 33.3% of S-1 patients and 25.0% of capecitabine patients (p = 0.754). In the two groups, Grade 4 adverse events were not observed and Grade 3 consisted of only two cases of diarrhea, and no patient suffered hematologic adverse event of Grade 2 or higher. However, the incidence of diarrhea (62.5% vs 33.3%, p = 0.014) and hand-foot syndrome (29.2% vs 0%, p = 0.016) were higher in capecitabine group. Other adverse events did not differ significantly between two groups.

Conclusions

The two preoperative chemoradiotherapy regimens were effective and safe for patients of locally advanced rectal cancer, but regimen with S-1 exhibited a lower incidence of adverse events.     

Coherent modeling of longitudinal causal effects on binary outcomes

Analyses of biomedical studies often necessitate modeling longitudinal causal effects. The current focus on personalized medicine and effect heterogeneity makes this task even more challenging. Toward this end, structural nested mean models (SNMMs) are fundamental tools for studying heterogeneous treatment effects in longitudinal studies. However, when outcomes are binary, current methods for estimating multiplicative and additive SNMM parameters suffer from variation dependence between the causal parameters and the noncausal nuisance parameters. This leads to a series of difficulties in interpretation, estimation, and computation. These difficulties have hindered the uptake of SNMMs in biomedical practice, where binary outcomes are very common. We solve the variation dependence problem for the binary multiplicative SNMM via a reparameterization of the noncausal nuisance parameters. Our novel nuisance parameters are variation independent of the causal parameters, and hence allow for coherent modeling of heterogeneous effects from longitudinal studies with binary outcomes. Our parameterization also provides a key building block for flexible doubly robust estimation of the causal parameters. Along the way, we prove that an additive SNMM with binary outcomes does not admit a variation independent parameterization, thereby justifying the restriction to multiplicative SNMMs.     

Elevated CpG island methylation of GCK gene predicts the risk of type 2 diabetes in Chinese males

Background

The GCK gene encodes hexokinase 4, which catalyzes the first step in most glucose metabolism pathways. The purpose of our study is to assess the contribution of GCK methylation to type 2 diabetes (T2D).

Methods and results

GCK methylation was evaluated in 48 T2D cases and 48 age- and gender-matched controls using the bisulphite pyrosequencing technology. Among the four CpG sites in the methylation assay, CpG4 and the other three CpGs (CpG1-3) were not in high correlation (r < 0.5). Significantly elevated methylation levels of GCK CpG4 methylation were observed in T2D patients than in the healthy controls (P = 0.004). A breakdown analysis by gender indicated that the association between CpG4 methylation and T2D was specific to males (P = 0.002). It is intriguing that another significant male-specific association was also found between GCK CpG4 methylation and total cholesterol (TC) concentration (r = 0.304, P = 0.036).

Conclusion

Our results showed that elevated GCK CpG4 methylation might suggest a risk of T2D in Chinese males. Gender disparity in GCK CpG4 methylation might provide a clue to elaborate the pathogenesis of T2D.     

Photosynthesis is improved by exogenous calcium in heat-stressed tobacco plants

Effects of exogenous calcium chloride (CaCl₂) (20 mM) on photosynthetic gas exchange, photosystem II photochemistry, and the activities of antioxidant enzymes in tobacco plants under high temperature stress (43 °C for 2 h) were investigated. Heat stress resulted in a decrease in net photosynthetic rate (P_n), stomatal conductance as well as the apparent quantum yield (AQY) and carboxylation efficiency (CE) of photosynthesis. Heat stress also caused a decrease of the maximal photochemical efficiency of primary photochemistry (F_v/F_m). On the other hand, CaCl₂ application improved P_n, AQY, and CE as well as F_v/F_m under high temperature stress. Heat stress reduced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), whereas the activities of these enzymes either decreased less or increased in plants pretreated with CaCl₂; glutathione reductase (GR) activity increased under high temperature, and it increased more in plants pretreated with CaCl₂. There was an obvious accumulation of H₂O₂ and O₂⁻ under high temperature, but CaCl₂ application decreased the contents of H₂O₂ and O₂⁻ under heat stress conditions. Heat stress induced the level of heat shock protein 70 (HSP70), while CaCl₂ pretreatment enhanced it. These results suggested that photosynthesis was improved by CaCl₂ application in heat-stressed plants and such an improvement was associated with an improvement in stomatal conductance and the thermostability of oxygen-evolving complex (OEC), which might be due to less accumulation of reactive oxygen species.     

Sphingomyelin synthase as a potential target for D609-induced apoptosis in U937 human monocytic leukemia cells

Tricyclodecan-9-yl-xanthogenate (D609) is a selective tumor cytotoxic agent. However, the mechanisms of action of D609 against tumor cells have not been well established. Using U937 human monocytic leukemia cells, we examined the ability of D609 to inhibit sphingomyelin synthase (SMS), since inhibition of SMS may contribute to D609-induced tumor cell cytotoxicity via modulating the cellular levels of ceramide and diacylglycerol (DAG). The results showed that D609 is capable of inducing U937 cell death by apoptosis in a dose- and time-dependent manner. The induction of U937 cell apoptosis was associated with an inhibition of SMS activity and a significant increase in the intracellular level of ceramide and decrease in that of sphingomyelin (SM) and DAG, which resulted in an elevation of the ratio between ceramide and DAG favoring the induction of apoptosis. In addition, incubation of U937 cells with C(6)-ceramide and/or H7 (a selective PKC inhibitor) reduced U937 cell viability; whereas pretreatment of the cells with a PKC activator, PMA or 1-oleoyl-2-acetylglycerol (OAG), attenuated D609-induced U937 cell apoptosis. These results suggest that SMS is a potential target of D609 and inhibition of SMS may contribute to D609-induced tumor cell death via modulation of the cellular levels of ceramide and DAG.     

三个小麦春化基因的时空表达特性分析(英文)

为明确小麦春化基因的时空表达特性,以中国春和洛旱2号小麦品种为试验材料,利用半定量RT-PCR技术,分析了3个春化基因VERNALIZATION1(VRN1)、VRN2和VRN3的时空表达特性。结果表明,VRN1在中国春的三叶期叶片和根、灌浆期的茎秆和旗叶、花药、胚珠和发育的种子中均有不同程度的表达。在开花前,表达水平呈上升趋势,而花后呈降低的趋势,在干种子和萌发种子的胚芽中没有检测到表达;在洛旱2号中,除了在三叶期的叶片和根中没有检测到表达外,VRN1的表达特性与中国春有相同的趋势。VRN2只在三叶期的叶片和萌发种子的胚芽中表达,在其他检测的组织中没有表达;VRN3的表达与VRN1的时空表达特性相似,但在根中未检测到表达。这一结果为进一步分析普通小麦品种春化发育的分子调控机理提供了重要信息。