野生型PTEN 过表达对体外活化肝星状细胞内钙离子浓度的影响

目的 探讨野生型第10 号染色体缺失的磷酸酶张力蛋白同源物基因（PTEN）过表达对体外活化肝星状细胞（HSC）内钙离子浓度的影响。方法 体外培养活化大鼠肝星状细胞系（HSC-T6）,利用腺病毒载体,将野生型PTEN 基因转染活化HSC ;Western blot 及实时荧光定量聚合酶链反应（qrt-PCR）检测HSC 的PTEN 蛋白及mRNA 表达;采用钙离子荧光探针Rhod-2/AM,于激光扫描共聚焦显微镜下检测HSC 内钙离子浓度变化。实验分组：① Control 组：腺病毒转染时以DMEM 代替病毒液;② Ad-GFP 组：转染表达绿色荧光蛋白（GFP）的对照空病毒Ad-GFP ;③ Ad-PTEN 组：转染携带野生型PTEN 基因并表达GFP 的重组腺病毒Ad-PTEN。结果 野生型PTEN 在活化大鼠HSC 大量表达,3 组HSC 内钙离子浓度比较,差异有统计学意义（P <0.05）,Ad-PTEN 组HSC 内钙离子浓度（251.60±90.88）低于Control 组（1 953.95±132.99）及Ad-GFP 组（1 937.57±115.17）,而Control 组与Ad-GFP 组之间HSC 内钙离子浓度比较,差异无统计学意义（P >0.05）。结论 野生型PTEN 过表达可降低体外活化大鼠HSC 内钙离子浓度。     

Intracellular localisation of proteins to specific cellular areas by nanocapsule mediated delivery

Nanocapsules are promising carriers with great potential for intracellular protein transport. Although many studies have intended to improve cell uptake efficacy, there is an increasing interest in understanding of subcellular distribution of cargoes inside cells, which is essential for purposeful delivery of biomolecules into specific sites within cells. Herein, we interrogate the intracellular localisation of exogenous proteins, including fluorescein isothiocyanate (FITC)-labelled bovine serum albumin (BSA) and green fluorescent protein (GFP), mediated by specially designed nanocapsules. The results show that the designed nanocapsules can deliver the two types of fluorescent proteins into different cellular destinations (cytosol, nucleus or the whole cell), depending on the composition of nanocapsules. Meanwhile, several impact factors that influence the distribution of proteins in cells have also been investigated, and the results suggest that the localisation of capsule-mediated proteins in cells is strongly affected by the surface properties of nanocapsules, the types of stabilisers and proteins, and environmental temperatures. The rational control of intracellular localised delivery of exogenous proteins as we demonstrated in this study might open new avenues to obtain desired magnitude of drug effects for modulating cell activity.     

Transporting carriers for intracellular targeting delivery via non-endocytic uptake pathways

Abstract

To develop novel therapies for clinical treatments, it increasingly depends on sophisticated delivery systems that facilitate the drugs entry into targeting cells. Profound understanding of cellular uptake routes for transporting carriers promotes the optimization of performance in drug delivery systems. Although endocytic pathway is the most important part of cellular uptake routes for many delivery systems, it suffers the trouble of enzymatic degradation of transporting carriers trapped in endosomes/lysosomes. Therefore, it is desirable to develop alternative transporting methods for delivery systems via non-endocytic pathways to achieve more effective intracellular delivery. In this review, we summarize the literature exploring transporting carriers that mediate intracellular delivery via non-endocytic pathways to present the current research status in this field. Cell-penetrating peptides, pH (low) insertion peptides, and nanoparticles are categorized to exhibit their ability to directly transport various cargos into cytoplasm via non-endocytic uptake in different cell lines. It is hoped that this review can spur the interesting on development of drug delivery systems via non-endocytic uptake pathway.     

Comparative protein profiling of B16 mouse melanoma cells susceptible and non-susceptible to alphavirus infection: Effect of the tumor microenvironment

Alphavirus vectors are promising tools for cancer treatment. However, relevant entry mechanisms and interactions with host cells are still not clearly understood. The first step toward a more effective therapy is the identification of novel intracellular alterations that could be associated with cancer aggressiveness and could affect the therapeutic potential of these vectors. In this study, we observed that alphaviruses efficiently infected B16 mouse melanoma tumors/tumor cells in vivo, whereas their transduction efficiency in B16 cells under in vitro conditions was blocked. Therefore, we further aimed to understand the mechanisms pertaining to the differential transduction efficacy of alphaviruses in B16 tumor cells under varying growth conditions. We hypothesized that the tumor microenvironment might alter gene expression in B16 cells, leading to an up-regulation of the expression of virus-binding receptors or factors associated with virus entry and replication. To test our hypothesis, we performed a proteomics analysis of B16 cells cultured in vitro and of B16 cells isolated from tumors, and we identified 277 differentially regulated proteins. A further in-depth analysis to identify the biological and molecular functions of the detected proteins revealed a set of candidate genes that could affect virus infectivity. Importantly, we observed a decrease in the expression of interferon α (IFN-α) in tumor-isolated cells that resulted in the suppression of several IFN-regulated genes, thereby abrogating host cell antiviral defense. Additionally, differences in the expression of genes that regulate cytoskeletal organization caused significant alterations in cell membrane elasticity. Taken together, our findings demonstrated favorable intracellular conditions for alphavirus transduction/replication that occurred during tumor transformation. These results pave the way for optimizing the development of strategies for the application of alphaviral vectors as a potent cancer therapy.     

COPI coat assembly occurs on liquid-disordered domains and the associated membrane deformations are limited by membrane tension

Cytoplasmic coat proteins are required for cargo selection and budding of tubulovesicular transport intermediates that shuttle between intracellular compartments. To better understand the physical parameters governing coat assembly and coat-induced membrane deformation, we have reconstituted the Arf1-dependent assembly of the COPI coat on giant unilamellar vesicles by using fluorescently labeled Arf1 and coatomer. Membrane recruitment of Arf1-GTP occurs exclusively on disordered lipid domains and does not induce optically visible membrane deformation. In the presence of Arf1-GTP, coatomer self-assembles into weakly curved coats on membranes under high tension, while it induces extensive membrane deformation at low membrane tension. These deformations appear to have a composition different from the parental membrane because they are protected from phase transition. These findings suggest that the COPI coat is adapted to liquid disordered membrane domains where it could promote lipid sorting and that its mechanical effects can be tuned by membrane tension.     

Polarized microtubule arrays in apical dendrites and axons

The polarization of microtubules within neurons in vivo is crucial in their role of determining the directions and speeds of intracellular transport. More than a decade ago, electron microscopy studies of mature hippocampal cultures indicated that their axons contained microtubules of uniform polarity and that dendrites contained microtubules of mixed polarity. Here, we evaluated polarity distributions in native brain tissues and in cultures by using multiphoton microscopy and second-harmonic generation from microtubules. We confirmed the expected polarized microtubule arrays in axons; however, we also unexpectedly found them ubiquitously in apical dendrites of mature hippocampal CA1 and cortical layer V pyramidal neurons. Some of these organized dendritic microtubule arrays extended for >270 microm with overall polarity of >80%. Our research indicates neurite-specific and age-dependent microtubule organizations that have direct implications for neuronal cargo transport.     

Palmatine, a protoberberine alkaloid, inhibits both Ca(2+)- and cAMP-activated Cl(-) secretion in isolated rat distal colon

BACKGROUND AND PURPOSE: The protoberberine alkaloid berberine has been reported to inhibit colonic Cl(-) secretion. However, it is not known if other protoberberine alkaloids share these effects. We have therefore selected another protoberberine alkaloid, palmatine, to assess its effects on active ion transport across rat colonic epithelium. EXPERIMENTAL APPROACH: Rat colonic mucosa was mounted in Ussing chambers and short circuit current (I (SC)), apical Cl(-) current and basolateral K(+) current were recorded. Intracellular cAMP content was determined by an enzyme immunoassay. Intracellular Ca(2+) concentration was measured with Fura-2 AM. KEY RESULTS: Palmatine inhibited carbachol-induced Ca(2+)-activated Cl(-) secretion and the carbachol-induced increase of intracellular Ca(2+) concentration. Palmatine also inhibited cAMP-activated Cl(-) secretion induced by prostaglandin E(2) (PGE(2)) or forskolin. Palmatine prevented the elevation of intracellular cAMP by forskolin. Determination of apical Cl(-) currents showed that palmatine suppressed the forskolin-stimulated, apical cAMP-activated Cl(-) current but not the carbachol-stimulated apical Ca(2+)-activated Cl(-) current. Following permeabilization of apical membranes with nystatin, we found that palmatine inhibited a carbachol-stimulated basolateral K(+) current that was sensitive to charybdotoxin and resistant to chromanol 293B. However, the forskolin-stimulated basolateral K(+) current inhibited by palmatine was specifically blocked by chromanol 293B and not by charybdotoxin. CONCLUSIONS AND IMPLICATIONS: Palmatine attenuated Ca(2+)-activated Cl(-) secretion through inhibiting basolateral charybdotoxin-sensitive, SK4 K(+) channels, whereas it inhibited cAMP-activated Cl(-) secretion by inhibiting apical CFTR Cl(-) channels and basolateral chromanol 293B-sensitive, KvLQT1 K(+) channels.     

Behavioral and brain temperature responses to salient environmental stimuli and intravenous cocaine in rats: effects of diazepam

Rationale While diazepam is an effective anxiolytic and somnolent drug in humans, its physiological and behavioral effects in animals are often variable. Differences in basal activity state (basal arousal) may be important in determining both this response variability and the pattern of drug influence on behavioral and physiological responses to natural arousing stimuli and other drugs. Objectives To evaluate the changes in brain, muscle, and skin temperatures, and in locomotion induced in rats by several arousing stimuli and intravenous (i.v.) cocaine; and to assess how these responses are modulated by diazepam at a relatively low dose (1 mg/kg, i.p.). Materials and methods Male rats were implanted with thermal probes in the nucleus accumbens (NAcc), temporal muscle, and subcutaneously, and equipped with a chronic i.v. catheter. They were exposed to 1-min tail-pinch, 1-min social interaction with another male and cocaine (1 mg/kg, i.v.) after administration of diazepam or saline. Results While the injection of either diazepam or saline resulted in similar locomotor activation and temperature responses, diazepam decreased basal brain and muscle temperatures for about 3 h; the temperature-decreasing effect of diazepam was oppositely related to basal brain temperature (r = −0.51). After diazepam, rats also showed weaker temperature and locomotor responses to both arousing stimuli; the effect was stronger for tail-pinch and for absolute temperature increases than relative changes. Although diazepam significantly decreased cocaine-induced locomotor activation, it had virtually no effects on cocaine-induced temperature responses in all locations. Conclusions In accordance with the “law of initial values”, the temperature-increasing effects of all tested arousing stimuli and temperature-decreasing effect of diazepam depend upon basal brain temperature. The greatest temperature effects are seen with arousing stimuli at low basal arousal (increases) and with diazepam at high basal arousal (decreases). This is a likely explanation for the variability seen with the physiological and behavioral effects of diazepam in animals.