ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα

ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα.     

单细胞动物和多细胞动物的激素印迹

激素印迹是单细胞动物和多细胞动物的一种生理现象,也是选择参与信号识别过程分子的工具。激素印迹后,受体记忆将遗传给子孙后代,因此其对进化的作用可能是很大的。同时,激素印迹还有利于物种的维持。另外,激素印迹过程还是具有终身效应的临时开放系统的一部分。没有印迹,就没有完全的受体成熟,而不成熟的受体是不能和适量的激素结合的。在围 期诸如治疗药物和环境污染剂等人工合成的物质分子易致错误或病理印迹。许多研究表明错误印迹对生物体具有重要的影响。当然,单细胞动物的激素印迹过程与多细胞动物并不完全一样。     

菹草附着物对营养盐浓度的响应及其与菹草衰亡的关系

在菹草衰亡阶段对5个静水水体中菹草叶片表面附着物进行野外调查,并将其与水体营养盐浓度、沉水植物衰亡程度进行相关性分析。附着物共调查Chl.a含量、干重、有机质含量和藻类数量4个指标,沉水植物衰亡程度用单位面积叶片Chl.a含量表示,水体营养盐含量测量了TP、TN和N/P 3个指标。结果显示：附着物生物量与水体营养盐状况存在一定的正相关;各个点的附着物生物量与菹草衰亡状况存在一定相关性但相关性趋势与水体污染程度有关。在污染程度较高的水体中附着物生物量与菹草衰亡程度呈正相关,在污染程度较低的水体中附着物生物量与菹草衰亡程度呈负相关。结论为富营养化湖泊中营养盐含量的增加会导致附着物生物量的增加,但附着物只在污染程度较高的水体中促进植物衰亡。     

同型半胱氨酸与超敏c反应蛋白在妊娠期高血压疾病中的研究进展

妊娠期高血压疾病是妊娠期特有的疾病,早期诊断对预后至关重要。妊娠期高血压疾病发病机制之一为血管内皮损伤,血浆中Hcy浓度升高会导致血管内皮损伤,血管内皮细胞功能失调常刺激超敏C反应蛋白（hs—cRP）的产生,而升高的hs—CRP可能导致血压上升。因此高血压和慢性炎症相互促进从而导致和加重了高血压。近年来血浆同型半胱氨酸（Hcy）、超敏C反应蛋白（hs—cRP）水平的升高与妊娠期高血压疾病的关系成为新的研究热点。本文将同型半胱氨酸、超敏C反应蛋白与妊娠期高血压疾病中的关系综述如下。     

Effect of Host Plants on Honeydew Production of an Invasive Mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae)

Honeydew production plays a key role in mutualism between the mealybugs and ants. However, no studies have focused on the amount and circadian rules of honeydew excreted by Phenacoccus solenopsis Tinsley, a new invasive species which has conditional mutualism with Solenopsis invicta Buren in China. To address this problem, we measured the weight and estimated honeydew production in all stages of development of the invasive mealybug, P. solenopsis, as well as its honeydew production on tomato (Solanum lycopersicun), Hibiscus rosa-sinensis, and cotton (Gossypium sp.) for 24 h. The honeydew excreted by each instar of the mealybug in H. rosa-sinensis was measured for 2 weeks. Our results revealed that the weight of mealybugs significantly varied at different development stages. Host plants had no significant effect on the weight of nymphs, although the weight of a single adult reared on S. lycopersicun was significantly heavier than those reared on H. rosa-sinensis and G. sp. The amount of honeydew excreted by the 1st instar nymphs in S. lycopersicum was significantly greater than that on H. rosa-sinensis and G. sp. Each instar mealybug produced more honeydew when fed with S. lycopersicum compared with H. rosa-sinensis and G. sp. The amount of honeydew excreted by mealybugs when provisioned with H. rosa-sinensis was no different from mealybugs provisioned with G. spp. while in the same instar. The amount of honeydew excreted by the 1st and 2nd instar nymphs was not significantly different on the same host plant. However, there was a significant difference between the 3rd instar nymph and the adult. The amount of honeydew excreted by a single adult when provisioned with H. rosa-sinensis decreased from 3085.3 μg to 572.0 μg in 2 weeks. The 2nd instar nymph, 3rd instar nymph, and adult excreted honeydew more frequently during the day than at night, while the frequency of honeydew excretion of the 1st instar nymph had no significant difference between daytime and night.     

Sirtuin 5 regulates the proliferation,invasion and migration of prostate cancer cells through acetyl‐CoA acetyltransferase 1

Sirtuin 5 (SIRT5) is a NAD⁺‐dependent class III protein deacetylase, and its role in prostate cancer has not yet been reported. Therefore, to explore the diagnosis and treatment of prostate cancer, we investigated the effect of SIRT5 on prostate cancer. Sirtuin 5 was assessed by immunohistochemistry in 57 normal and cancerous prostate tissues. We found that the tissue expression levels of SIRT5 in patients with Gleason scores ≥7 were significantly different from those in patients with Gleason scores <7 (P < .05, R > 0). Further, mass spectrometry and pathway screening experiments showed that SIRT5 regulated the activity of the mitogen‐activated protein kinase (MAPK) pathway, which in turn modulated the expression of MMP9 and cyclin D1. Being a substrate of SIRT5, acetyl‐CoA acetyltransferase 1 (ACAT1) was regulated by SIRT5. SIRT5 also regulated MAPK pathway activity through ACAT1. These results revealed that SIRT5 promoted the activity of the MAPK pathway through ACAT1, increasing the ability of prostate cancer cells to proliferate, migrate and invade. Overall, these results indicate that SIRT5 expression is closely associated with prostate cancer progression. Understanding the underlying mechanism may provide new targets and methods for the diagnosis and treatment of the disease.     

Locating an antagonist in the 5-HT3 receptor binding site using modeling and radioligand binding

We have used a homology model of the extracellular domain of the 5-HT(3) receptor to dock granisetron, a 5-HT(3) receptor antagonist, into the binding site using AUTODOCK. This yielded 13 alternative energetically favorable models. The models fell into 3 groups. In model type A the aromatic rings of granisetron were between Trp-90 and Phe-226 and its azabicyclic ring was between Trp-183 and Tyr-234, in model type B this orientation was reversed, and in model type C the aromatic rings were between Asp-229 and Ser-200 and the azabicyclic ring was between Phe-226 and Asn-128. Residues located no more than 5 A from the docked granisetron were identified for each model; of 26 residues identified, 8 were found to be common to all models, with 18 others being represented in only a subset of the models. To identify which of the docking models best represents the ligand-receptor complex, we substituted each of these 26 residues with alanine and a residue with similar chemical properties. The mutant receptors were expressed in human embryonic kidney (HEK)293 cells and the affinity of granisetron determined using radioligand binding. Mutation of 2 residues (Trp-183 and Glu-129) ablated binding, whereas mutation of 14 other residues caused changes in the [(3)H]granisetron binding affinity in one or both mutant receptors. The data showed that residues both in and close to the binding pocket can affect antagonist binding and overall were found to best support model B.     

Loss of editing activity during the evolution of mitochondrial phenylalanyl-tRNA synthetase

Accurate selection of amino acids is essential for faithful translation of the genetic code. Errors during amino acid selection are usually corrected by the editing activity of aminoacyl-tRNA synthetases such as phenylalanyl-tRNA synthetases (PheRS), which edit misactivated tyrosine. Comparison of cytosolic and mitochondrial PheRS from the yeast Saccharomyces cerevisiae suggested that the organellar protein might lack the editing activity. Yeast cytosolic PheRS was found to contain an editing site, which upon disruption abolished both cis and trans editing of Tyr-tRNA(Phe). Wild-type mitochondrial PheRS lacked cis and trans editing and could synthesize Tyr-tRNA(Phe), an activity enhanced in active site variants with improved tyrosine recognition. Possible trans editing was investigated in isolated mitochondrial extracts, but no such activity was detected. These data indicate that the mitochondrial protein synthesis machinery lacks the tyrosine proofreading activity characteristic of cytosolic translation. This difference between the mitochondria and the cytosol suggests that either organellar protein synthesis quality control is focused on another step or that translation in this compartment is inherently less accurate than in the cytosol.