埃兹蛋白参与调控的信号转导通路研究进展

埃兹蛋白（Ezrin）是细胞骨架连接蛋白（Ezrin-Radixin-Moesin,ERM）家族成员之一,主要分布于细胞皮层。Ezrin作为膜蛋白和肌动蛋白连接蛋白,在调控细胞的形态、生长、生存、黏附、增殖和迁徙等生物学功能中发挥重要作用。其作用机制复杂,涉及Rho、PKA、PKC、MAPK及细胞凋亡等多条信号传导通路。因此,研究Ezrin相关的信号转导,对认识疾病的发展及治疗具有重要意义。     

Anterior‐posterior regionalized gene expression in the Ciona notochord

Background: In the simple ascidian chordate Ciona, the signaling pathways and gene regulatory networks giving rise to initial notochord induction are largely understood and the mechanisms of notochord morphogenesis are being systematically elucidated. The notochord has generally been thought of as a non‐compartmentalized or regionalized organ that is not finely patterned at the level of gene expression. Quantitative imaging methods have recently shown, however, that notochord cell size, shape, and behavior vary consistently along the anterior‐posterior (AP) axis. Results: Here we screen candidate genes by whole mount in situ hybridization for potential AP asymmetry. We identify 4 genes that show non‐uniform expression in the notochord. Ezrin/radixin/moesin (ERM) is expressed more strongly in the secondary notochord lineage than the primary. CTGF is expressed stochastically in a subset of notochord cells. A novel calmodulin‐like gene (BCamL) is expressed more strongly at both the anterior and posterior tips of the notochord. A TGF‐β ortholog is expressed in a gradient from posterior to anterior. The asymmetries in ERM, BCamL, and TGF‐β expression are evident even before the notochord cells have intercalated into a single‐file column. Conclusions: We conclude that the Ciona notochord is not a homogeneous tissue but instead shows distinct patterns of regionalized gene expression. Developmental Dynamics 243:612–620, 2014. © 2013 Wiley Periodicals, Inc.     

ATP缺失时大鼠近端肾小管上皮细胞骨架重组与ERM蛋白的重分布相关

目的:探讨ATP缺失时大鼠近端肾小管上皮细胞(NRK52E细胞)肌动蛋白细胞骨架重组情况及其可能机制.方法:用含0.1 μmol/L antimycin A的ATP缺失缓冲液处理培养的NRK52E细胞,建立细胞的体外ATP缺失模型;采用FITC标记的鬼笔环肽标记纤维型肌动蛋白(F-actin),用流式细胞仪检测技术分析肌动蛋白细胞骨架的重组情况;用Western blot及免疫印迹技术检测ATP缺失后NRK52E细胞内骨架组分(Triton不溶组分)及上清组分(Triton可溶组分)中ERM(Ezrin/Radixin/Moesin)蛋白的分布改变.结果:体外ATP缺失模型建立,各实验组细胞内ATP浓度呈时间依赖性的下降(P＜0.05);ATP缺失后,NRK52E细胞内纤维型肌动蛋白的量渐增,且肌动蛋白的聚合程度随ATP缺失时间延长而增加(P＜0.05);ATP缺失后,ERM蛋白从细胞骨架解离进入胞浆,且ERM蛋白从细胞骨架的解离程度随ATP缺失的程度的增加而增加(P＜0.05).结论:ATP缺失后NRK52E细胞骨架重组可能与ERM蛋白的重分布相关.     

ROCKⅡ对细胞滋养细胞ERM蛋白表达及细胞浸润能力调节的研究

目的:探讨Rho/ROCK/ERM通路与细胞滋养细胞浸润能力的关系。方法:免疫荧光细胞化学法定位ROCKⅡ和ERM在体外培养细胞滋养细胞中的表达,Western blot检测ROCKⅡ活性被抑制时细胞滋养细胞中p-ERM表达变化,MTT实验、体外细胞侵袭实验和细胞运动实验检测ROCKⅡ活性被抑制时细胞滋养细胞生长、运动、浸润能力的改变。结果:ROCKⅡ和ERM在细胞滋养细胞的胞浆中表达;随着ROCKⅡ活性下降,p-ERM表达下降,细胞生长、浸润、运动受到抑制,呈浓度依赖关系。结论:ROCKⅡ在体外培养的细胞滋养细胞中可能通过调节ERM蛋白来调节细胞的生长、浸润和运动能力,提示Rho/ROCK/ERM通路可能在人孕早期胚泡植入过程中发挥作用。     

Ezrin, radixin, and moesin are components of Schwann cell microvilli.

Ezrin, radixin, and moesin (ERM proteins), as well as the neurofibromatosis 2 (NF2) tumor suppressor merlin/schwannomin, all belong to the protein 4.1 family, yet only merlin is a tumor suppressor in Schwann cells. To gain insight into the possible functions of ERM proteins in Schwann cells, we examined their localization in peripheral nerve, because we have previously shown that merlin is found in paranodes and in Schmidt-Lanterman incisures. All three ERM proteins were highly expressed in the microvilli of myelinating Schwann cells that surround the nodal axolemma as well as in incisures and cytoplasmic puncta in the vicinity of the node. In all of these locations, ERM proteins were colocalized with actin filaments. In contrast, ERM proteins did not surround nodes in the CNS. The colocalization of ERM proteins with actin indicates that they have functions different from those of merlin in myelinating Schwann cells.     

Alcohol and the cognitive aspects of choice reaction time

In a repeated-measures experiment 18 men and 8 women were given ethanol which raised their mean blood alcohol concentration (BAC) to 0, 21, 50 and 73 mg/100 ml. Using the ERM apparatus (Schuhfried Instruments, Austria), which measures choice reaction time to a task with high cognitive content, it was found that both decision and reaction time increased as a function of rising BAC, and that movement time was not affected.     

Predicting toxicity in marine sediment in Taranto Gulf (Ionian Sea,Southern Italy) using Sediment Quality Guidelines and a battery bioassay

The goal of this study was to assess coastal marine pollution in the Mar Piccolo and Taranto Gulf (Ionian Sea, Southern Italy) by combining chemical and toxicological data in order to compare and integrate both approaches. Pollutants levels, traditionally, have limited ability to predict adverse effects on living resources. Moreover, in order to provide information on the ecological impact of sediment contamination on aquatic biota Numerical Sediment Quality Guidelines (SQGs) and sediment toxicity bioassays were carefully recommended. In this study ERL (effect range low)/ERM (effect range medium value) and TEL (threshold effect level)/PEL (probable effect level) guidelines have been used. Bioassays were performed with two species of amphipods Gammarus aequicauda and Corophium insidiosum, one species of isopod Idotea baltica and bivalve Mytilus galloprovincialis larvae. The TEL/PEL analysis suggested that, especially for stations 1 and 2, sediments in Mar Piccolo should contain acutely toxic concentrations of metals. In particular Hg content, in station 1, was about 17 times PEL value. 96 h LC₅₀ and 48 h EC₅₀ values were estimated for cadmium, copper and mercury in these species using the static acute toxicity test. M. galloprovincialis larvae was more sensitive than other species to all the reference toxicants tested (EC₅₀ determined for cadmium copper and mercury were of 0.59, 0.11 and 0.01 mg/l respectively). Significant differences in sensitivity of species tested to all reference toxicants (ANOVA p < 0.001) were recorded. Bioassays with these species allowed to estimated sediment toxicity from the different studied sites. On the basis of results obtained a good agreement was reported between chemical data and response of the biological endpoints tested.     

Radixin is required to maintain apical canalicular membrane structure and function in rat hepatocytes

BACKGROUND & AIMS: Ezrin-radixin-moesin proteins are cross-linkers between the plasma membrane and actin filaments. Radixin, the dominant ezrin-radixin-moesin protein in hepatocytes, has been reported to selectively tether multidrug-resistance-associated protein 2 to the apical canalicular membrane. However, it remains to be determined if this is its primary function. METHODS: An adenovirus-mediated short interfering RNA (siRNA) was used to down-regulate radixin expression in collagen sandwich-cultured rat hepatocytes and morphologic and functional changes were characterized quantitatively. RESULTS: In control cultures, an extensive bile canalicular network developed with properly localized apical and basolateral transporters that provided for functional excretion of fluorescent cholephiles into the bile canalicular lumina. siRNA-induced suppression of radixin was associated with a marked reduction in the canalicular membrane structure as observed by differential interference contrast microscopy and F-actin staining, in contrast to control cells exposed to adenovirus encoding scrambled siRNA. Indirect immunofluorescence showed that apical transporters (multidrug-resistance-associated protein 2, bile salt export pump, and multidrug-resistance protein 1) dissociated from their normal location at the apical membrane and were found largely associated with Rab11-containing endosomes. Localization of the basolateral membrane transporter, organic anion transporting polypeptide 2 (Oatp2), was not affected. Consistent with this dislocation of apical transporters, the biliary excretion of glutathione-methylfluorescein and cholylglycylamido-fluorescein was decreased significantly in the radixin-deficient cells, but not in the control siRNA cells. CONCLUSIONS: Radixin is essential for maintaining the polarized targeting and/or retaining of canalicular membrane transporters and is a critical determinant of the overall structure and function of the apical membrane of hepatocytes.