Comparison of transforming growth factor β and a human tumour-derived suppressor factor

Summary Serum-free supernatants from the human melanoma cell line G361 contain a factor that can potently suppress the generation of tumouricidal lymphokine-activated killer (LAK) cells in response to interleukin-2. To characterise the suppressive factor of tumour origin we performed a number of physicochemical and functional comparisons with another immunosuppressive protein, transforming growth factor (TGF). The bioactivity of tumour-derived suppressor factor (TDSF), assayed by suppression of LAK cell generation, was unaffected by a reducing agent but lost when denatured with a chaotropic agent. In contrast, TGF was inactivated by reduction but not denaturation. TDSF lost bioactivity in conditions of pH less than 4, whereas TGF showed no loss of activity. The TDSF moiety has an estimated pI of 4.3 and a molecular mass of 69–87 kDa. This differs from published values of pI 9.5, and 25 kDa molecular mass for TGF. Anti-TGF antiserum reversed the effects of TGF but did not affect the suppression of LAK cell generation caused by TDSF. These findings provide compelling evidence that the TDSF moiety is not TGF, and may be a novel immunoregulatory cytokine.     

CD95 ligand--death factor and costimulatory molecule?

The CD95 ligand is involved as a death factor in the regulation of activation-induced cell death, establishment of immune privilege and tumor cell survival. In addition, CD95L may serve as a costimulatory molecule for T-cell activation. Alterations in expression or shedding of membrane and soluble CD95L are associated with numerous diseases, and underscore the pathophysiological relevance of the CD95/CD95L system. In most cases, the causal link between altered CD95L expression and pathophysiology is unknown. Given the potency of the molecule to regulate death and survival of many different cell types, the control of CD95L production, transport, storage, shedding and inactivation is of tremendous biological and clinical interest. This review summarizes the current knowledge, hypotheses and controversies about CD95L as a multifunctional ligand and receptor. It considers the different roles of membrane and soluble forms of CD95L and the complex networks of intracellular dynamics of protein trafficking, as well as the potential bidirectional signal transduction capacity of CD95L, with a focus on molecular interactions that have been worked out over the past years.     

Host factor requirements and some properties of ΦXtB

Summary Replication of XtB, a capsid mutant of bacteriophage X174, depends on the host functions directed by the E. coli genes dnaE, dnaF, dnaG, dnaZ, lig and rep. The cellular products of dnaA, dnaB, dnaC(D), dnaI, dnaP, polA, polB and xth genes are, however, dispensable for the viral growth. In these host factor requirements, XtB resembles phages K and St-1, rather than X174. Host ranges of XtB, St-1 and K overlap considerably, and growth temperature of the three phages is somewhat higher than that of X174. Furthermore, XtB is, like K, inactivated by antiserum against St-1. XtB may thus fill an evolutionary gap between the X174 group and the St-1 group.     

Expression of core-binding factor α1 and osteocalcin in fluoride-treated fibroblasts and osteoblasts

To study the effects and importance of fluoride on FBs in the development of extraperiosteal calcification and the ossification of skeletal fluorosis, the presence of the osteogenic phenotype, which is indicated by the expression of core-binding factor α1 (Cbfa1) and osteocalcin (OCN), in an FB cell line (L929) and in osteoblasts (OBs) exposed to fluoride was determined. Fibroblasts and osteoblasts were exposed to different concentrations of fluoride (0, 0.0001, 0.001, 0.1, 1.0, 10.0 and 20.0 mg/L F⁻). By using RT-PCR and ELISA, the mRNA levels of Cbfa1 and OCN were measured at 48 h, and the protein levels of Cbfa1 and OCN were measured at 2, 4, 24, 48 and 72 h. The data demonstrated the following: (1) The Cbfa1 protein level in fluoride-treated fibroblasts clearly increased at 48 h in the groups treated with 0.0001, 0.001, 0.1, 1.0 and 20.0 mg/L F⁻. The Cbfa1 protein level of the group treated with 10 mg/L F⁻ at 72 h was higher than that of the control group. The level of Cbfa1 mRNA in the fibroblasts was much higher at 48 h in the group treated with 10.0 mg/L F⁻ than in the control group. (2) The OCN protein level in fluoride-treated fibroblasts was significantly higher than that of the control group in the 0.0001, 0.1, 1.0, 10.0 and 20.0 mg/L F⁻ groups at 2 h, and in the 0.001 and 0.1 F⁻ groups at 4 h. A slightly higher level of OCN mRNA in fluoride-treated fibroblasts was also found in the 1.0 and 20.0 mg/L F⁻ groups compared to the control group. (3) The expressions of Cbfa1 and OCN in osteoblasts treated with the same experimental conditions as the fibroblasts were up-regulated by fluoride following the same trend as in the fibroblasts. Our results showed an increase in the expression of Cbfa1 and OCN in fibroblasts and osteoblasts exposed to fluoride and suggested that the osteogenic function of fibroblasts induced by fluoride could play an important role in the development of extraperiosteal ossification during skeletal fluorosis.     

Morningness: protective factor for sleep-related and emotional problems in childhood and adolescence?

The relationship between morningness/eveningness, sleep, and psychological problems is well documented in adults as well as in adolescents. However, research on the circadian orientation and its concomitants in younger children is scarce. The authors investigated the distribution of morningness/eveningness and its connection to sleeping and psychological problems in 91 children and 151 adolescents in Austria. The authors found that morning (M) types had less sleep-related and psychological problems than intermediate (I) and evening (E) types, respectively. Among children, M-types suffered less from daytime sleepiness (females: χ(2)((2))?= 8.1, p =?.017; males: χ(2)((2))?= 14.8, p =?.001). Among adolescents, M-types showed fewer sleep-wake problems (females: χ(2)((2))?= 17.5, p 相似文献   

Effect of platelet activating factor on leukocytes II. Enhancement of eosinophil chemotactic factor and β-glucuronidase release

Synthetic 1-O-alkyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine (PAF) and 1-O-alkyl-sn-glyceryl-3-phosphorylcholine (lyso-PAF) have previously been shown to induce chemotaxis and chemokinesis of human neutrophils. We present here data showing that these agents are inactive by themselves, but that they enhance neutrophil secretion once it has been initiated by a calcium ionosphore or by zymosan. Two substances, the lipid eosinophil chemotactic factor (ECF) and the lysosomal enzyme β-glucuronidase, are used as markers for neutrophil release. PAF augments secretion of both substances in a dose-dependent fashion, with lyso-PAF being less potent. The kinetics of enhancement are very rapid (<2 min) and are not reversible by washing of the cells. A pyrazoline derivative that inhibits arachidonate cyclo-oxygenation and lipoxygenation, reduces the enhancing effect of PAF and lyso-PAF. PAF, and less so lyso-PAF, are thus potentially important modulators of neutrophil secretion during inflammatory processes.     

Effects of transforming growth factor β, tumor necrosis factor α and interferon γ on pancreatic islet β-cell responsiveness to transforming growth factor α

The insulin-producing pancreatic islet -cell, characterized by low proliferative potential, is normally not responsive to the polypeptide epidermal growth factor (EGF) or its homolog transforming growth factor (TGF-). Since EGF receptors in other tissues can be up-regulated by other growth factors and by cytokines, we have in this paper investigated whether such a -cell responsiveness to TGF-, or EGF, can be conferred by co-culture with interferon (IFN-), tumor necrosis factor (TNF-) or transforming growth factor (TGF-) in various combinations. To this end, fetal rat pancreatic islets enriched in -cells were isolated and cultured for 3 days with or without 200 pM or 20 nM TGF-. It was found that neither of these TGF- concentrations affected -cell mitogenesis, insulin content or insulin secretion. However, IFN- (1000 U/ml) evoked a modest stimulation of -cell replication, while suppressing insulin secretion and leaving the islet insulin content unaltered. TNF- (1000 U/ml), on the other hand, affected none of these parameters either alone or in any combination with TGF- or IFN-. However, when TNF- or IFN-, either alone or in combination, were combined with the cytokine interleukin-1, this resulted in islet disintegration, whereas the latter cytokine alone did not exert any gross necrotic changes evident by light microscopy. TGF- (500 pM) stimulated insulin secretion but did not influence islet insulin content or -cell mitogenesis either alone or in combination with TGF- (200 pM or 20 nM). In no instance could any mitogenic or secretory response to low or high concentrations of TGF- be conferred by IFN-, TNF- or TGF- whether used alone or in combinations. Hence, responsiveness to TGF- or EGF in the -cell obviously cannot be achieved by any of these peptides.Abbreviations EGF epidermal growth factor - IFN- interferon - TGF- transforming growth factor - TGF- transforming growth factor - TNF- tumor necrosis factor      

γ-Secretase and presenilin mediate cleavage and phosphorylation of vascular endothelial growth factor receptor-1

We have reported previously that pigment epithelium-derived factor (PEDF) can, via γ-secretase-mediated events, inhibit VEGF-induced angiogenesis in microvascular endothelial cells by both (a) cleavage and intracellular translocation of a C-terminal fragment of VEGF receptor-1 (VEGFR1) and (b) inhibition of VEGF-induced phosphorylation of VEGFR1. Using site-direct mutagenesis and transfection of wild type and mutated receptors into endothelial cells, we showed that transmembrane cleavage of VEGFR1 occurs at valine 767 and that a switch from valine to alanine at this position prevented cleavage and formation of a VEGFR1 intracellular fragment. Using siRNA to selectively knock down protein-tyrosine phosphatases (PTPs) in endothelial cells, we demonstrated that vascular endothelial PTP is responsible for dephosphorylation of activated VEGFR1. PEDF up-regulation of full-length presenilin 1 (Fl.PS1) facilitated the association of vascular endothelial PTP and VEGFR1. Knockdown of Fl.PS1 prevented dephosphorylation of VEGFR1, whereas up-regulation of Fl.PS1 stimulated VEGFR1 dephosphorylation. Fl.PS1 associated with VEGFR1 within 15 min after PEDF treatment. In conclusion, we determined the PEDF-mediated events responsible for VEGFR1 signaling and identified full-length presenilin as a critical adaptor molecule in the dephosphorylation of VEGFR1. This greater understanding of the regulation of VEGFR1 signaling will help identify novel anti-VEGF therapeutic strategies.     

Relationship of tumor necrosis factor α expression with activation of sphingomyelinase and lipid peroxidation after removal of cholestatic factor

The goal of this work was to study the expression of tumor necrosis factor α (TNFα), sphingomyelin cycle activation, and lipid peroxidation (LPO) processes after the removal of a cholestatic factor in the liver subjected to different durations of cholestasis. Restored bile flow after a 9-day hepatic cholestasis normalized sphingomyelinase (SMase) activity and levels of TNFα and LPO products. The removal of a cholestatic factor after a 12-day cholestasis did not normalize the studied parameters: SMase activity and the levels of TNFα and LPO products remained much higher compared to control. A significant positive correlation between TNFα expression, SMase activity, and LPO rate has been revealed. The obtained data indicate that hepatocyte apoptosis after bile outflow restoration in late cholestasis can be due to the activation of the sphingomyelin cycle, LPO, and TNFα expression. The synergistic interaction can sharply increase the proapoptotic capacity of each of these factors since TNFα activates SMase and LPO, SMase activity depends on the LPO rate, while ceramide, an SMase-produced secondary messenger of apoptosis, can induce oxidative stress.     

Corticotropin-releasing factor family and its receptors: tumor therapeutic targets?

Urocortin (UCN) and corticotropin-releasing factor (CRF) are members of CRF family. Though CRF is mainly distributed in central nervous system (CNS), UCN has been reported to play biologically diverse roles in several systems such as cardiovascular, respiratory, digestive, reproductive, stress, immunologic system, etc. UCN and CRF bind to two known receptors, CRFR1 and CRFR2, to function. Both CRF receptors are distributed in CNS and periphery tissues, and their expression in cancer tissues has been reported. Now there are many documents indicating UCN/CRF play an important role in the regulation of carcinogenesis. There is also evidence indicating UCN/CRF have anticancer effects via CRFRs. This paper will review the effects of CRF family in cancers.     

Nonbenzamidine acylsulfonamide tissue factor–factor VIIa inhibitors

Aminoisoquinoline and isoquinoline groups have successfully replaced the more basic P1 benzamidine group of an acylsulfonamide factor VIIa inhibitor. Inhibitory activity was optimized by the identification of additional hydrophobic and hydrophilic P′ binding interactions. The molecular details of these interactions were elucidated by X-ray crystallography and molecular modeling. We also show that decreasing the basicity of the P1 group results in improved oral bioavailability in this chemotype.     

Epidermal growth factor, transforming growth factor-α, and epidermal growth factor receptor expression and localization in the canine endometrium during the estrous cycle and in bitches with pyometra

Gene expression and immunohistochemical localization of epidermal growth factor (EGF), transforming growth factor-α (TGF-α), and epidermal growth factor receptor (EGF-R) were compared between the endometrium of bitches (Canis familiaris) with pyometra accompanied by cystic endometrial hyperplasia (CEH) and that of healthy bitches at similar stages of the estrous cycle. In normal bitches, endometrial TGF-α mRNA levels were highest at proestrus and gradually decreased as the cycle progressed to anestrus. Epidermal growth factor receptor mRNA levels were not significantly affected by the stage of the estrous cycle. Epidermal growth factor mRNA levels were higher at Day 35 of diestrus than at other stages of the estrous cycle (P < 0.05). In bitches with pyometra, endometrial TGF-α and EGF-R mRNA levels did not differ significantly from those at diestrus in normal bitches, but EGF mRNA levels were lower than those at Day 35 of diestrus in normal bitches (P < 0.05). In normal bitches, positive immunohistochemical staining for TGF-α, EGF, and EGF-R was mainly present in the glandular and luminal epithelial cells of the endometrium. In contrast, in bitches with pyometra, immunoreactivity for EGF was clearly present in endometrial stromal cells. Inflammatory cells that had infiltrated the endometrial stroma stained strongly for TGF-α and EGF-R. Luminal and glandular epithelial cells also stained positive for EGF-R. In conclusion, expression of TGF-α by inflammatory cells and a low level of expression and differential localization of EGF may be involved in aberrant growth of endometrial glands and development of CEH.