The Structure of Tight Junctions in Mouse Submandibular Gland

Salivary gland cells are joined by junctional complexes consisting of a tight junction (TJ), zonula adherens and one or more desmosomes. TJs regulate paracellular permeability, maintain separate apical and basolateral membrane domains, and serve as signaling centers. We examined TJs of mouse submandibular glands (SMG) in thin sections and freeze‐fracture replicas. TJs between acinar cells and between intercalated duct cells had 2–6 parallel strands on the protoplasmic fracture face, with occasional branches, interconnections and free ends, and corresponding grooves on the extracellular face. Granular duct cell TJs had 2–30 strands, a depth of ≤0.5 μm, and occasional loops extending further basally. Where 3 or 4 cells met, the TJs extended basally ≤1 μm and consisted of 2 parallel boundary strands into which the apical strands inserted. Quantitative analyses showed significant differences in TJ complexity, measured by fractal geometry, and strand number of acinar compared to granular duct cells, and a greater number of strands in male compared to female granular ducts. Pilocarpine stimulation increased TJ strand number in female acinar cells, and increased complexity of male granular duct cell TJs. As the salivary gland water channel aquaporin 5 (AQP5) has been proposed to functionally interact with TJs to regulate salivary fluid composition, we also studied glands from AQP5 knock‐out mice. In males lacking AQP5, granular duct TJs were more complex than those of wild‐type mice, and exhibited more strands following pilocarpine stimulation. The results demonstrate specific gender, cell type and genetic differences in TJ structure and response to stimulation. Anat Rec, 2010. © 2009 Wiley‐Liss, Inc.     

Tumor Suppressor Scribble Regulates Assembly of Tight Junctions in the Intestinal Epithelium

Formation of the epithelial barrier and apico-basal cell polarity represent two characteristics and mutually dependent features of differentiated epithelial monolayers. They are controlled by special adhesive structures, tight junctions (TJs), and polarity protein complexes that define the apical and the basolateral plasma membrane. The functional interplay between TJs and polarity complexes remains poorly understood. We investigated the role of Scribble, a basolateral polarity protein and known tumor suppressor, in regulating TJs in human intestinal epithelium. Scribble was enriched at TJs in T84 and SK-CO15 intestinal epithelial cell monolayers and sections of normal human colonic mucosa. siRNA-mediated knockdown of Scribble in SK-CO15 cells attenuated development of epithelial barrier and inhibited TJ reassembly independently of other basolateral polarity proteins Lgl-1 and Dlg-1. Scribble selectively co-imunoprecipitated with TJ protein ZO-1, and ZO-1 was important for Scribble recruitment to intercellular junctions and TJ reassembly. Lastly, Scribble was mislocalized from TJs and its expression down-regulated in interferon-γ-treated T84 cell monolayers and inflamed human intestinal mucosa in vivo. We conclude that Scribble is an important regulator of TJ functions and plasticity in the intestinal epithelium. Down-regulation of Scribble may mediate mucosal barrier breakdown during intestinal inflammation.The epithelial cell layer in the gut plays two crucial physiological functions. One function involves the formation of the physical barrier that separates body compartments from the gut lumen and protects underlying tissues from pathogen invasion and other harmful external stimuli.^1,2 Another function involves the regulation of bidirectional passages of solutes and macromolecules, which is essential for nutrients supply and removal of body waste.^3–5 Both barrier integrity and vectorial transport in the intestinal epithelium are regulated by specialized cellular structures known as tight junctions (TJs). TJs represent a complex network of protein fibrils within the plasma membrane, which encircle the apical region of the epithelial cell perimeter in close proximity to the gut lumen.⁶ TJ fibrils are composed of adhesive transmembrane proteins, which associate with ensembles of scaffolding proteins at the cytosolic face of the membrane. The paracellular barrier is created by homotypical interactions between transmembrane TJ components of contacting epithelial cells such as occludin, members of the claudin family and junctional adhesion molecule-A (JAM-A).^6–8 These cell-cell adhesions are enhanced and regulated by cytosolic scaffolds such as members of zonula occludens (ZO) family and AF-6/afadin, which cluster and stabilize transmembrane TJ components at the plasma membrane.^6–8 Although other junctional complexes at the plasma membrane, viz., adherens junctions (AJs) and desmosomes also mediate cell-cell adhesions, TJs play a unique role in sealing the paracellular space and creating the epithelial barrier.^1,6,7The mature TJs not only mediate barrier function of the intestinal epithelium, but also contribute to the formation and maintenance of the apico-basal cell polarity.^9–11 Such cell polarity implies that the apical and basolateral domains of the plasma membrane differ in the composition of transporters, channels and receptors; therefore ensuring directionality of secretion and adsorption processes in epithelial cells.^12,13 TJs regulate the epithelial cell polarity by creating a fence that prevents intermixing of protein and lipid constituents of the apical and basolateral plasma membrane domains.^9–11 However, TJs alone are not sufficient for the apico-basal polarization of epithelial cells. In this process apical junctions cooperate with specialized protein polarity complexes that control the “identity” of distinct plasma membrane domains.Epithelial cells have three major evolutionarily conserved polarity complexes that were initially identified and named in model invertebrates. They are known as Crumbs (composed by Crumbs, PALS, and PATJ proteins), Par (Par3, Par6, and atypical protein kinase C) and Scribble (including Scribble, Disks Large (Dlg) and Lethal Giant Larvae (Lgl)) complexes.^11,14–16 Crumbs and Par cooperate to define the apical plasma membrane, whereas Scribble is critical for establishment of the basolateral membrane domain.^11,14–16 A number of studies have demonstrated a functional interplay between epithelial junctions and the polarity complexes, where these entities mutually affect each other. Thus, several members of the Crumbs and Par complexes were shown to regulate TJ assembly via either direct binding to TJ components (ZO-1 and claudins) or indirect mechanisms, involving modulation of vesicle trafficking and actin cytoskeleton remodeling.^11,14–16 In contrast, the role of the Scribble polarity complex in the regulation of epithelial TJs is not well understood,^17,18 although such a role is supported by several lines of evidence. For example, mutations in any member of this complex in Drosophila resulted in dramatic disorganization of epithelial architecture that included loss of columnar cell shape and cell-cell adhesions.^19–21 Furthermore, several reports have linked decreased protein levels of mammalian Scribble and Lgl with progression and invasiveness of epithelial tumors,^22–24 which is also accompanied by down-regulation of TJs.²⁵ Two recent studies have addressed the role of Scribble in the regulation cell-cell adhesions in mammalian epithelia; however their results appear to be inconsistent. Indeed, siRNA-mediated depletion of this protein in Madin-Darby canine kidney (MDCK) epithelial cells resulted in altered cell morphology and disorganized E-cadherin-based AJs.²⁶ However, no changes in cell morphology or AJ structure were observed following the silencing of Scribble expression in MCF10A human mammary epithelial cells.²⁷ Such inconsistent results may reflect tissue- specific effects of Scribble depletion, and they indicate that more work is needed to establish functional links between Scribble and TJs in human epithelia under normal physiological conditions and in disease states.In this study, we examined the role of Scribble in the regulation of the intestinal epithelial barrier and reorganization of TJs. Our results demonstrate that Scribble is important for TJ barrier function and assembly, and that it may regulate junctions by interacting with the TJ scaffold, ZO-1. We also report that Scribble is mislocalized and its expression down-regulated in the intestinal epithelium by inflammatory conditions in vitro and in vivo.     

Expression of CD26 (Dipeptidyl Peptidase IV) on Resting and Activated Human T-Lymphocytes

CD26 is an activation antigen which is expressed on the surface of human T-lymphocytes. It has been characterized to be the dipeptidyl peptidase IV (DPP IV). Considerable amounts of CD26 are already present on resting T-lymphocytes. The expression of CD26 is enhanced by T-cell mitogens or antigens. A correlation of CD26 expression and of enhanced enzymatic activity was observed after T-cell activation. Our data indicate that not only the immunoreactivity, but also the enzymatic activity of CD26 are detectable on the cell surface. In addition, de novo expression of CD26 was demonstrated on CD26-negative T-cells after mitogenic or antigenic stimulation. CD26 expression is initiated during the G1 phase of the cell cycle. The expression occurs nearly simultaneously with HLA-DR, but later than CD25. Similar to CD25 and HLA-DR, CD26 is not a permanent marker on the surface of T-lymphocytes, but is down-regulated after 7 days of culture. When testing the influence of interleukin 1, interleukin 2, tumour necrosis factor, and interferon-gamma on the expression of CD26, no effect was found on unstimulated or on mitogen-stimulated T-lymphocytes. The binding of two different monoclonal antibodies against CD26 (anti-DPP IV and anti-Tal) to resting and activated T-lymphocytes revealed a different pattern of immunoreactivity. Resting T-lymphocytes reacted stronger with anti-DPP IV than with anti-Tal. However, binding of the two monoclonal antibodies to T-cell blasts did not show significant differences. These data indicate that CD26 may be expressed in differently modulated configurations on the surface of T-cells, which may be associated with a distinct status of activation and/or function.     

Development of Endothelial Paracellular Clefts and their Tight Junctions in the Pial Microvessels of the Rat

The microvessels of the pia mater lack an investment with astrocyte processes but nonetheless have a high transendothelial electrical resistance which has caused them to be regarded as part of the blood-brain barrier. This high resistance is known to be acquired in the perinatal period. The aim of our study was to relate the known physiological changes with differentiation of the endothelial paracellular clefts and especially of their tight junctions which provide the basis for the high transendothelial resistance of blood-brain barrier vessels. Tight junctions of endothelial cell paracellular clefts in pial microvessels were examined by transmission electron microscopy using goniometric tilting to reveal and measure membrane separations at tight junctions in fetal, postnatal and adult rats. These tight junctional membrane separations narrowed over the period (E16:6.3 nm, D1:6.4 nm, D7:5.4 nm) and differentiated into two groups by the adult stage: one with a membrane separation of 2.8 nm and the staining characteristics of non-brain endothelial junctions, and the other with no detectable membrane separation and the staining characteristic of blood-brain barrier endothelial junctions. This patchy and incomplete differentiation of pial tight junctions into a blood-brain barrier-like form could result either from non-uniform exposure to inductive signals or to local variation in responsiveness to such agents. Although these changes in junction organization may be related to the known increase in pial transendothelial resistance in the perinatal period, we have not yet identified any sharply defined structural change which coincides with this physiological event.     

Differential Expression of the Tight Junction Proteins,Claudin‐1, Claudin‐4, Occludin,ZO‐1, and PAR3, in the Ameloblasts of Rat Upper Incisors

Tight junctions (TJs) create a paracellular permeability barrier to restrict the passage of ions, small solutes, and water. Ameloblasts are enamel‐forming cells that sequentially differentiate into preameloblasts, secretory, transition, and ruffle‐ended and smooth‐ended maturation ameloblasts (RAs and SAs). TJs are located at the proximal and distal ends of ameloblasts. TJs at the distal ends of secretory ameloblasts and RAs are well‐developed zonula occludens, but other TJs are moderately developed but incomplete zonula occludens (ZO) or less‐developed macula occludens. We herein examined the immunofluorescence localization of TJ proteins, 10 claudin isoforms, occludin, ZO‐1, and PAR3, a cell polarity‐related protein, in ameloblasts of rat upper incisors. ZO‐1 and claudin‐1 were detected at both ends of all ameloblasts except for the distal ends of SAs. Claudin‐4 and occludin were detected at both ends of transition and maturation ameloblasts except for the distal ends of SAs. PAR3 was detected at the proximal TJs of all ameloblasts and faintly at the distal TJs of early RAs. These results indicate that functional zonula occludens formed at the distal ends of the secretory ameloblasts and RAs consisted of different TJ proteins. Therefore, the distal TJs of secretory ameloblasts and RAs may differentially regulate the paracellular permeability to create a microenvironment suitable for enamel deposition and enamel maturation, respectively. In addition, PAR3 may be principally involved in the formation and maintenance of the proximal, but not distal, TJs. Anat Rec, 291:577–585, 2008. © 2008 Wiley‐Liss, Inc.     

Anti-T Lymphocyte Globulin (ATG) Induces Generation of Regulatory T Cells, at Least Part of Them Express Activated CD44

We show here that the anti-T lymphocyte immunoglobulin (ATG) can induce Treg cells following 24-h incubation in human peripheral blood mononuclear cells (PBMCs). The ATG-induced Treg cells express known cell surface markers (e.g., CD25, FoxP3) and suppress the proliferation of autologous responder PBMCs, stimulated with allogeneic PBMCs, when added into the mixed lymphocyte culture (MLC) at zero time point or 48 h later. We expanded the characteristics of the ATG-induced human Treg cells by showing that they express a novel biomarker designated "activated CD44". ATG-induced Treg cells retain their suppressor function after freezing and thawing or irradiation. Suppression of MLC by ATG-induced Treg cells is consistently seen when the Treg cells and the responder cells were derived from the same donor, but not when they derived from different donors. Finally, patients undergoing stem cell transplantation and conditioned with ATG generate in vivo Treg cells that suppress MLC.     

Freshly Isolated Tumour-Infiltrating T-Lymphocytes have a High Cytotoxic Potential, as Measured by their Ability to Induce Apoptosis in the Target Cell

To test if freshly isolated tumour-infiltrating lymphocytes (TIL) can induce apoptosis in a target cell, we have combined two previously described methods. Because TIL predominantly are T-lymphocytes. we have applied a redirected approach. When the target cells that express anti-human-CD3 monoclonal antibodies in their membranes bind to the T cell receptor-associated CD3-complex, signals are generated, which activate T cell effector mechanisms. This approach circumvents problems with MHC-restriction and allows for functional testing of all T cells, irrespective of their clonal specificity.
In order to assay for induction of DNA fragmentation, we have labelled the target cell nuclei with [³H]thymidine. Upon harvesting fragmented DNA are washed away. Electrophoretic analysis of the fragmented DNA demonstrated the characteristic 'ladder' pattern, consistent with apoptosis.
This rapid and simple assay monitors the capacity of different T cells to induce apoptosis in the target cell. It depends on intercellular interactions and clearly discriminates between different T cell subsets. With this assay we demonstrate the functional integrity of the cytotoxic effector arm of freshly isolated TIL.     

Conformation-Dependent Recognition of a Protein by T-Lymphocytes: Apomyoglobin-Specific T-Cell Clone Recognizes Conformational Changes Between Apomyoglobin and Myoglobin

A T-cell clone specific to apomyoglobin was generated. It was prepared from a T-cell culture obtained by in vitro driving of lymph node cells with apomyoglobin from SJL mice that have been primed in vivo with apomyoglobin. In proliferative assays, the T-cell clone responded to apomyoglobin but did not recognize native myoglobin or any of the synthetic peptides corresponding to the six T sites of myoglobin. The demonstration that a T-cell clone can be isolated, whose specificity is directed entirely to apomyoglobin and not to its counterpart myoglobin, with an identical amino acid composition, indicates the importance of the three-dimensional structure in the presentation of the protein to T cells.     

Occludin as direct target for glucocorticoid-induced improvement of blood–brain barrier properties in a murine in vitro system

Homeostasis of the central nervous system (CNS) microenvironment is essential for its normal function. It is maintained by the blood–brain barrier (BBB) which regulates the transport of molecules from blood into brain and backwards. The integrity of the BBB is compromised in many disorders of the human CNS; therapeutical strategies for several of these diseases include treatment with glucocorticoids, but the molecular basis of how glucocorticoids regulate BBB permeability is not understood. Here, we report the generation and characterization of a murine immortalized brain (cerebral) capillary endothelial (cEND) cell line which expresses the BBB marker occludin at intercellular tight junctions (TJ). Hydrocortisone at physiological concentrations induced upregulation of occludin, accompanied by a threefold enhancement of transendothelial electrical resistance to values up to 1000 Ωcm². Insulin enhanced the glucocorticoid response. At the molecular level, hydrocortisone induces increase of occludin at protein and mRNA levels by activation of the glucocorticoid receptor (GR) and its binding to putative glucocorticoid responsive elements in the occludin promoter. At the same time, insulin potentiated the ligand-dependent GR transactivation via induction of the GR in this in vitro system. This study thus provides insights into the molecular processes of barrier genesis, and may help to elucidate mechanisms of brain pathology at the microvascular level.     

Activated protein C resistance, the factor V Leiden mutation, and a laboratory testing algorithm

OBJECTIVES: To present the current understanding of factor V Leiden and activated protein C resistance, and to propose a laboratory testing algorithm. DATA SOURCES: Publications on MEDLINE with the terms factor V Leiden or activated protein C resistance through mid 2001, as well as publications in the authors' files, were screened for inclusion in this report. STUDY SELECTION: Original studies that report a novel finding on testing or clinical features of activated protein C resistance or factor V Leiden are included. Data Extraction.-The novel or key findings from the selected studies are analyzed. DATA SYNTHESIS: Protein C and protein S are the integral components of an anticoagulation pathway that limits fibrinogen conversion to fibrin through the degradation of factors Va and VIIIa. When factor Va is resistant to degradation by activated protein C, this anticoagulation pathway does not operate properly, and patients have an increased risk for thrombosis. This report describes the protein C/protein S pathway, the significance of activated protein C resistance and the factor V Leiden mutation, and the clinical testing used to detect activated protein C resistance and the factor V Leiden mutation. A proposed laboratory testing algorithm is also provided. CONCLUSIONS: Factor V Leiden is a risk factor for venous thrombosis and it is particularly common in white populations. A laboratory testing algorithm is proposed.     

Electrophoretic Polymorphism of a Hamster Pentraxin, Female Protein (Amyloid P Component)

Serum amyloid P protein (SAP) is a ubiquitous vertebrate protein distinguished by its conservative evolution and paucity of polymorphic forms. The SAP homologue in the Syrian hamster ( Mesocricetus auratus ), called Female Protein [FP(SAP)] is unique because its synthesis is controlled by sex hormones. These observations were limited to the commercially available standard Syrian hamsters that are descendants of three littermates captured in Syria in 1930. The authors examined FP(SAP) expression in nine inbred lines of Syrian hamsters that were derived from 12 wild hamsters captured in 1971. In general, regulation of FP(SAP) was similar in the new wild hamster strains, although a novel electrophoretically slower FP(SAP) was found in three of the strains. The slow FP(SAP) was not distinguished by size, antigenicity, binding capacity, or regulation. The electrophoretic difference was still apparent after deglycosylation. Hybrid offspring coexpressed both fast and slow FP monomers and formed a unique hybrid pentamer that had a new mobility between the fast and slow parent FP(SAP). The origin of this unusual polymorphism could be related to the amyloidogenesis associated with expression of FP(SAP) in the standard Syrian hamster.     

Rutin,a Flavonoid and Principal Component of Saussurea Involucrata,Attenuates Physical Fatigue in a Forced Swimming Mouse Model

This study investigated the antifatigue effects of rutin, a flavonoid extracted from the ethyl acetate extract of S. involucrata. Mice were subjected to a weight-loaded forced swim test (WFST) on alternate days for 3 wk. Rutin was administered orally to the mice for 7 days in dosages of 15, 30, and 60 mg/kg body weight, and several biomarkers of physical fatigue were evaluated: swimming time, change in body weight, lipid peroxidation, lactic acid (LA), glycogen, and the activities of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx). On Day 7, the rutin-treated mice had a 3-fold longer exhaustive swimming time than the control mice, as well as significantly reduced blood LA concentrations. The 15, 30, and 60 mg/kg body weight rutin-supplemented groups displayed 11.2%, 22.5%, and 37.7% reduced malondialdehyde (MDA) concentrations, respectively, in brain and muscle tissues compared with the control exercised group. Our results indicated that the administration of rutin protected the mice against the depletion of SOD and GPx activities significantly. Following 7 days of rutin treatment, we sacrificed the mice and analyzed their soleus muscle and brain for peroxisome proliferator-activated receptor-α coactivator (PGC-1α) and sirtuin 1 (SIRT1) mRNA expression. We observed that rutin treatment increased PGC-1α and SIRT1 mRNA and protein expression. The changes in these markers of mitochondrial biogenesis were associated with increased maximal endurance capacity. The application of 2D gel electrophoresis to analyze the rutin-responsive protein profiles in the WFST mouse brain further revealed the upregulation of the CB1 cannabinoid receptor-interacting protein 1, myelin basic protein, Rho GDP dissociation inhibitor (GDI) alpha, and TPI, indicating that rutin might inhibit anxiety through the upregulation of the expression of anxiety-associated proteins. Western blot analysis of MAPK expression further confirmed the antianxiety effects of rutin. Our study results thus indicate that rutin treatment ameliorates the various impairments associated with physical fatigue.     

Nonrestorative Sleep as a Distinct Component of Insomnia

Study Objectives:

Explore characteristics of nonrestorative sleep (NRS) in prospectively defined subgroups of individuals with NRS symptoms, investigate whether NRS can occur independently of difficulties initiating and maintaining sleep (DIS/DMS), and determine its effect on waking function.

Design:

Cross-sectional and longitudinal population-based study comparing patterns of daytime symptoms, and their persistence, in cohorts of subjects with NRS symptoms grouped according to presence or absence of DIS and DMS.

Setting:

28 sleep centers in the US.

Participants:

Subjects reporting awakening unrestored or unrefreshed at least 3 times weekly over the previous 3 months were classified, based on self-reported sleep problems, to DIS (n = 138), DMS (n = 44), DIS+DMS (n = 125), and NRS-only (no DIS or DMS; n = 192) cohorts. Eighty healthy volunteers formed a control group.

Interventions:

None.

Measurements and Results:

Polysomnography confirmed DIS and/or DMS in 56/138 (41%), 18/44 (41%), and 37/125 (30%) subjects in DIS, DMS, and DIS+DMS cohorts, respectively; and absence of DIS or DMS in 115/192 (60%) NRS-only subjects and 52/80 (65%) healthy volunteers. Multiple subject-reported endpoints including the Endicott Work Productivity Scale, Pittsburgh Insomnia Rating Scale, Restorative Sleep Questionnaire, and SF-36, showed that NRS-only subjects had significantly impaired daytime function relative to healthy volunteers, comparable to impairment affecting subjects with DIS and/or DMS. Symptoms persisted over 3 months.

Conclusions:

This study confirms that NRS can occur independently of other components of insomnia. Daytime symptoms were as severe in individuals with NRS-only as those whose NRS symptoms were combined with DIS or DMS.

Citation:

Roth T; Zammit G; Lankford A; Mayleben D; Stern T; Pitman V; Clark D; Werth JL. Nonrestorative sleep as a distinct component of insomnia. SLEEP 2010;33(4):449-458.     

Activated,N-substituted acrylamide polymers for antibody coupling: Application to a novel membrane-based immunoassay

A room-temperature-precipitable, activated terpolymer consisting of N-isopropylacrylamide (NIPAAm)/N n-butylacrylamide(nBAAm)/N acryloxysuccinimide(NASI) (LCST = 7-13°C) at a monomer feed ratio of 60:40:2.5, respectively, was prepared and conjugated to an antibody. The conjugate was evaluated in a novel cellulose acetate (CA) membrane-based immunoassay which utilizes the especially strong physical attachment of the polymer to CA to bind and concentrate the polymer attached protein onto the membrane. When compared in the CA membrane immunoassay to the antibody-poly(NIPAAm) conjugate prepared via anhydrous copolymerization of NIPAAm and NASI at the monomer feed ratio of 40 : 1, respectively, the performance of the NIPAAm/nBAAm/NASI terpolymer was superior to that of the NIPAAm/NASI copolymer (LCST = 32°C) when the studies were carried out at room temperature. However, the terpolymer and copolymer gave equivalent performance when the assay mixture was heated to 45°C. These results indicate the importance of the LCST of the polymer component of the Ab-polymer conjugate to its adsorption and binding on the CA membrane.     

Inhibition of the Adherence of T-Lymphocytes to Epithelial Cells by a Cyclic Peptide Derived from Inserted Domain of Lymphocyte Function-Associated Antigen-1

Tissue inflammation is characterized by aggravated leukocyte infiltration into the sites of inflammation. The mechanism requires the interactions of leukocyte adhesion-molecules and their ligands in the inflamed tissues. In this study, we demonstrate that a cyclic peptide cLAB.L [cyclo1, 12-PenITDGEATDSGC], derived from the "inserted" or I-domain of LFA-1 is able to inhibit the adherence of T-lymphocytes to the epithelial cell monolayers. This inhibition has been thought to involve the disruption of LFA-1/ICAM-1 interaction. The heterotypic adhesion of phorbol ester-activated Molt-3 cells and IFN--induced Caco-2 monolayers was inhibited upon treatment of the monolayers with monoclonal antibodies (MAbs) to adhesion molecules or with cLAB.L peptide. The adhesion can be inhibited by MAbs to ICAM-1, ICAM-2, and VCAM-1, and cLAB.L peptide in a concentration-dependent manner. However, none of the individual uses of these molecules led to a total inhibition. The inhibitory activity of cLAB.L is greatly reduced by low temperature and the absence of cell activation. Treatment of cLAB.L peptide may trigger an early event of apoptosis on activated but not on non-activated Molt-3 cells; no indication of peptide-induced apoptosis was found on Caco-2 cells. Taken together, data from this work suggest that cLAB.L may have applications to direct cell-targeted delivery during tissue inflammation.     

Trophoblastic Neoplasms Express Fatty Acid Synthase,Which May Be a Therapeutic Target via Its Inhibitor C93

Fatty acid synthase (FASN) is an emerging tumor-associated marker and a promising antitumor therapeutic target. In this study, we analyzed the expression of FASN in normal and molar placentas, as well as gestational trophoblastic neoplasia, and assessed the effects of a new FASN inhibitor, C93, on cellular proliferation and apoptosis in choriocarcinoma cells. Using a FASN-specific monoclonal antibody, we found that FASN immunoreactivity was detected in the cytotrophoblast and intermediate (extravillous) trophoblast of normal and molar placentas, as well as in placental site nodules. All choriocarcinomas (n = 33), 90% of epithelioid trophoblastic tumors (n = 20), and 60% of placental site trophoblastic tumors (n = 10) exhibited FASN positivity. FASN expression was further confirmed in vitro by Western blot and real-time PCR. Treatment of JEG3 and JAR cells with C93 induced significant apoptosis through the caspase-3/caspase-9/poly(ADP)ribose polymerase pathway. Cell cycle progression was not affected by the inhibitor. In summary, the data indicate that FASN is expressed in the majority of gestational trophoblastic neoplasias, and is essential for choriocarcinoma cells to survive and escape from apoptosis. FASN inhibitors such as C93 warrant further investigation as targeted therapeutic agents for metastatic and chemoresistant gestational trophoblastic neoplasia.Gestational trophoblastic neoplasms (GTNs) represent a relatively uncommon type of gynecological tumor that behaves differently from other cancers. GTNs include choriocarcinoma, placental site trophoblastic tumor (PSTT), and epithelioid trophoblastic tumor (ETT).¹ Clinically, GTNs are one of the few human tumors that are often cured by chemotherapy and/or local tumor resection. More specifically, nonmetastatic, low-risk GTNs treated with methotrexate or actinomycin D are almost always successfully treated, but cure rates in high-risk metastatic disease decrease to 80% to 90%, despite combination chemotherapy, surgery, and radiation.^2,3 Also, approximately 5% of low-risk and 25% of high-risk patients respond poorly to initial treatment and require salvage chemotherapeutic regimens that include platinum or paclitaxel. Unfortunately, high-risk patients who fail or relapse after first-line EMA-CO (etoposide, methotrexate, dactinomycin, vincristine, and cyclophosphamide) therapy demonstrate an overall survival of 60% to 80%.^2,4,5 Therefore, newer therapeutic regimens are needed to reduce the toxicity associated with current multi-agent chemotherapies and to salvage the occasional nonoperable patient with recurrent or chemoresistant disease.⁶ Until the fundamental biology of GTNs becomes more clearly understood, development of more novel therapies remains empirical.Clinical promise has been shown by target-based therapies designed to inactivate molecular pathways that are essential for tumor cell growth and survival. Unlike standard chemotherapy, which indiscriminately affects proliferating cells, whether normal or neoplastic, inhibitors that target specific pathways in cancer have the potential to selectively eliminate tumor cells, thereby achieving maximal therapeutic effect with minimal adverse side effects. Recent examples of successful anticancer agents include gefitinib, a small kinase inhibitor that targets epidermal growth factor receptors, and trastuzumab (Herceptin), a humanized antibody that targets HER2/neu receptors. Given the success of molecular targeting in previous clinical trials, targeted therapy in the treatment of metastatic GTNs might be applied by tailoring management based on the expression profile of tumor’s specific markers.Fatty acid synthase (FASN) is an intracellular enzyme that promotes the NADPH-dependent condensation of malonyl-CoA and acetyl-CoA to palmitate in endogenous lipogenesis.^7,8 In normal cells, FASN levels are generally low due to the presence of abundant dietary lipids, but in neoplastic cells, FASN expression is up-regulated despite the presence of dietary lipids. Upregulation of FASN is observed in several types of human cancer including carcinomas of the breast, colon, ovary, and prostate.^{9,10,11,12,13,14} In this study, we assessed the biological role of FASN in GTN and in normal and molar placentas. We found that FASN expression in cytotrophoblast and intermediate (extravillous) trophoblastic cells is unique in that both normal and neoplastic trophoblastic cells express FASN. This is in contrast to most other tissue types, which preferentially express FASN in tumor cells, but not in their normal or benign counterparts. Moreover, inactivation of FASN led to massive apoptosis in choriocarcinoma cell lines, suggesting that FASN expression is required for the survival of choriocarcinoma cells. These results suggest that FASN inhibitor may be potentially useful as a new therapeutic reagent for advanced stage choriocarcinoma.     

FlhA, a Component of the Flagellum Assembly Apparatus of Pseudomonas aeruginosa, Plays a Role in Internalization by Corneal Epithelial Cells

Pseudomonas aeruginosa invades various epithelial cell types in vitro and in vivo. The P. aeruginosa genome possesses a gene (flhA) which encodes a protein that is believed to be part of the export apparatus for flagellum assembly and which is homologous to invA of Salmonella spp. Because invA is required for invasion of Salmonella spp., a role for flhA in P. aeruginosa invasion was explored using cultured rabbit corneal epithelial cells. An flhA mutant of P. aeruginosa strain PAO1 was constructed and was shown to be nonmotile. Complementation with flhA in trans restored motility. Corneal cells were infected for 3 h with the wild type (PAO1), the flhA mutant, the flhA mutant complemented with flhA in trans, an flhA mutant containing the plasmid vector control, or an fliC mutant (nonmotile mutant control). Invasion was quantified by amikacin exclusion assays. Both the flhA and the fliC mutants invaded at a lower level than the wild-type strain did, suggesting that both fliC and flhA played roles in invasion. However, loss of motility was not sufficient to explain the reduced invasion by flhA mutants, since centrifugation of bacteria onto cells did not restore invasion to wild-type levels. Unexpectedly, the flhA mutant adhered significantly better to corneal epithelial cells than wild-type bacteria or the fliC mutant did. The percentage of adherent bacteria that invaded was reduced by approximately 80% for the flhA mutant and approximately 50% for the fliC mutant, showing that only part of the role of flhA in invasion involves fliC. Invasion was restored by complementing the flhA mutant with flhA in trans but not by the plasmid vector control. Intracellular survival assays, in which intracellular bacteria were enumerated after continued incubation in the presence of antibiotics, showed that although flhA and fliC mutants had a reduced capacity for epithelial cell entry, they were not defective in their ability to survive within those cells after entry. These results suggest that the flagellum assembly type III secretion system plays a role in P. aeruginosa invasion of epithelial cells. Since the flhA mutants were not defective in their ability to adhere to corneal epithelial cells, to retain viability at the cell surface, or to survive inside epithelial cells after entry, the role of flhA in invasion of epithelial cells is likely to occur during the process of bacterial internalization.     

去细胞坐骨神经天然支架的成分分析

背景：目前周围神经去细胞的方法较多,应用较多的是化学萃取法和液氮冻融法,但是化学萃取法耗时较长,而液氮冻融法则去除细胞不彻底。作者在查阅大量文献和多次实践的基础上,最终确定了冻融+化学萃取+机械振荡的优化法对坐骨神经进行脱细胞处理。 目的：对优化法制备的去细胞坐骨神经天然支架进行形态学分析,并对其成分进行鉴定。 方法：取Wistar大鼠双侧坐骨神经,随机分为2组,对照组不做特殊处理,实验组用冻融+化学萃取+机械振荡的优化法进行脱细胞处理。 结果与结论：用优化法制备的去细胞坐骨神经天然支架呈三维管状立体结构,许旺细胞、髓鞘及轴突去除完全。经免疫组化鉴定,Ⅰ型、Ⅲ型胶原和层粘连蛋白等细胞外基质主要成分得到保留。