[Radiation-induced meningiomas: analysis of 33 cases]. / Radioindutsirovannye meningiomy: analiz 33 nablyudenii.

BACKGROUND: Development of meningiomas correlating with irradiation has been described in the last century. Different biological features of radiation-induced meningiomas depending on dose and type of irradiation have been observed in recent years. MATERIAL AND METHODS: There were 8848 patients (women - 74.3%) with intracranial meningiomas for the period from 2000 to 2014 who underwent surgery at the Burdenko Neurosurgical Center. Radiation-induced meningiomas were identified in 33 patients (13 (38%) men and 20 (62%) women) aged 16-76 years (median 56 years). Medical data were retrospectively analyzed. Follow-up period ranged from 5 to 22 years (median 12) after verification of histological diagnosis. Meningiomas were preceded by X-ray irradiation of the scalp for ringworm (microsporia or trichophytosis) in 26 cases (79%) (group A). Group B enrolled 7 (21%) patients after previous radiotherapy for other tumors (retinoblastoma, chiasmal glioma, pituitary adenoma, basalioma). Data were compared using Mann-Whitney and Fisher's exact tests. RESULTS AND DISCUSSION: Incidence of radiation-induced meningiomas was 0.37% in our sample. Meningioma diagnosis dates after X-ray epilation (median 52 years) significantly differed from that after radiotherapy (median 22 years) (Mann-Whitney test, p=0.0003). Primary multiple meningiomas were diagnosed only in the 1st group (Fisher's exact test, p=0.0005). Recurrent meningiomas after the first surgery were more common in the first group (58%) compared to the second one (14%) (Mann-Whitney test, p=0.0003). CONCLUSIONS: The latency period is shorter after radiotherapy (median 22 years compared to 52 years after X-ray epilation). Incidence of atypical and malignant meningiomas directly correlates with irradiation dose. Approximately equal incidence of radiation-induced meningiomas after X-ray epilation in women and men can indicate other mechanisms of development of these tumors in comparison with spontaneous ones. Radiotherapy is followed by occurrence of meningiomas within the irradiated area. These tumors are usually single. In case of X-ray epilation, the tumors may be localized anywhere within the intracranial space (convexital and/or parasagittal localization in 77% of cases). Multiple neoplasms occur in 42% of cases. Refusal of head X-ray epilation for the treatment of a ringworm for the last 50 years may be followed by reduced incidence of radiation-induced meningiomas, especially multiple ones. However, extended indications for radiotherapy of various brain diseases can result an increase of the incidence of meningiomas within the irradiated area.

Fruit Consumption is Associated with Alterations in Microbial Composition and Lower Rates of Pouchitis.

BACKGROUND: Patients with ulcerative colitis [UC] who undergo proctocolectomy with an ileal pouch-anal anastomosis commonly develop pouch inflammation [pouchitis]. Pouchitis develops in a previously normal small intestine and may involve environmental factors. We explored whether diet and microbiota alterations contributed to the pathogenesis of pouchitis. METHODS: Patients were recruited and prospectively followed at a comprehensive pouch clinic. Pouch behaviour was clinically defined as a normal pouch [NP] or pouchitis. Patients completed Food Frequency Questionnaires [FFQs]. Faecal samples were analysed for microbial composition [16S rRNA gene pyrosequencing]. RESULTS: Nutritional evaluation was performed in 172 patients [59% females], and of these, faecal microbial analysis was performed in 75 patients (microbiota cohort: NP [n = 22], pouchitis [n = 53]). Of the entire cohort, a subgroup of 39 [22.6%] patients had NP at recruitment [NP cohort]. Of these, 5 [12.8%] developed pouchitis within a year. Patients at the lowest tertile of fruit consumption [<1.45 servings/day] had higher rates of pouchitis compared with those with higher consumption [30.8% vs 3.8%, log rank, p = 0.03]. Fruit consumption was correlated with microbial diversity [r = 0.35, p = 0.002] and with the abundance of several microbial genera, including Faecalibacterium [r = 0.29, p = 0.01], Lachnospira [r = 0.38, p = 0.001], and a previously uncharacterized genus from the Ruminococcaceae family [r = 0.25, p = 0.05]. Reduction in fruit consumption over time was associated with disease recurrence and with reduced microbial diversity [Δ = -0.8 ± 0.3, p = 0.008]. CONCLUSIONS: Fruit consumption is associated with modification of microbial composition, and lower consumption was correlated with the development of pouchitis. Thus, fruit consumption may protect against intestinal inflammation via alteration of microbial composition.

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection.

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non-stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 µg per mg protein) compared with CI-, NI- and I-treated groups (94.5, 64 and 62.3 µg mg(-1), respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re-infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3-75%, higher than in the non-exposed control (40.6% mortality).

PKCη promotes senescence induced by oxidative stress and chemotherapy.

Senescence is characterized by permanent cell-cycle arrest despite continued viability and metabolic activity, in conjunction with the secretion of a complex mixture of extracellular proteins and soluble factors known as the senescence-associated secretory phenotype (SASP). Cellular senescence has been shown to prevent the proliferation of potentially tumorigenic cells, and is thus generally considered a tumor suppressive process. However, some SASP components may act as pro-tumorigenic mediators on premalignant cells in the microenvironment. A limited number of studies indicated that protein kinase C (PKC) has a role in senescence, with different isoforms having opposing effects. It is therefore important to elucidate the functional role of specific PKCs in senescence. Here we show that PKCη, an epithelial specific and anti-apoptotic kinase, promotes senescence induced by oxidative stress and DNA damage. We further demonstrate that PKCη promotes senescence through its ability to upregulate the expression of the cell cycle inhibitors p21(Cip1) and p27(Kip1) and enhance transcription and secretion of interleukin-6 (IL-6). Moreover, we demonstrate that PKCη creates a positive loop for reinforcing senescence by increasing the transcription of both IL-6 and IL-6 receptor, whereas the expression of IL-8 is specifically suppressed by PKCη. Thus, the presence/absence of PKCη modulates major components of SASP. Furthermore, we show that the human polymorphic variant of PKCη, 374I, that exhibits higher kinase activity in comparison to WT-374V, is also more effective in IL-6 secretion, p21(Cip1) expression and the promotion of senescence, further supporting a role for PKCη in senescence. As there is now considerable interest in senescence activation/elimination to control tumor progression, it is first crucial to reveal the molecular regulators of senescence. This will improve our ability to develop new strategies to harness senescence as a potential cancer therapy in the future.

Comparative study of infection with Tetrahymena of different ornamental fish species.

Tetrahymena is a ciliated protozoan that can infect a wide range of fish species, although it is most commonly reported in guppies (Poecilia reticulata). The aim of this study was to compare the susceptibility to infection with Tetrahymena of five different ornamental fish species from two different super orders. The species examined were platy (Xiphophorus), molly (Poecilia sphenops) and angelfish (Pterophyllum scalare) of the Acanthopterygii super order (which also includes guppies) and goldfish (Carassius auratus auratus) and koi carp (Cyprinus carpio) of the Ostariophysi super order. These two super orders are phylogenetically distant from each other. Infection with Tetrahymena resulted in parasite invasion of internal organs, skin and muscle in all fish species. A relatively strong inflammatory response was observed in infected goldfish and koi, with negligible response in fish species of the Acanthopterygii super order. Guppies were the most susceptible to Tetrahymena infection, exhibiting a mortality rate of 87% and 100% in two separate experiments. A high mortality rate was also observed in platy (77%), while that of molly and angelfish was significantly lower (23% and 33%, respectively). Goldfish and koi carp were less susceptible to infection compared with guppies (24% and 59% mortality, respectively). Immunization studies revealed that the Tetrahymena are immunogenic, since infection of koi carp increased their Tetrahymena immobilization response by approximately three-fold at 3 weeks post infection, while immunization with Tetrahymena plus adjuvant increased their immobilization response by approximately 30-fold.

T cell activation induces direct binding of the Crk adapter protein to the regulatory subunit of phosphatidylinositol 3-kinase (p85) via a complex mechanism involving the Cbl protein.

The Crk adapter proteins are assumed to play a role in T lymphocyte activation because of their induced association with tyrosine-phosphorylated proteins, such as ZAP-70 and Cbl, and with the phosphatidylinositol 3kinase regulatory subunit, p85, following engagement of the T cell antigen receptor. Although the exact mechanism of interaction between these molecules has not been fully defined, it has been generally accepted that Crk, ZAP-70, and p85 interact with tyrosine-phosphorylated Cbl, which serves as a major scaffold protein in activated T lymphocytes. Our present results demonstrate a cell activation-dependent reciprocal co-immunoprecipitation of CrkII and p85 from lysates of Jurkat T cells and a direct binding of CrkII to p85 in an overlay assay. The use of bead-immobilized GST fusion proteins indicated a complex mechanism of interaction between CrkII and p85 involving two distinct and mutually independent regions in each molecule. A relatively high affinity binding of the CrkII-SH3(N) domain to p85 and the p85-proline-B cell receptor-proline (PBP) region to CrkII was observed in lysates of either resting or activated T cells. Direct physical interaction between the CrkII-SH3(N) and the p85-PBP domain was demonstrated using recombinant fusion proteins and was further substantiated by binding competition studies. In addition, immobilized fusion proteins possessing the CrkII-SH2 and p85-SH3 domains were found to pull down p85 and CrkII, respectively, but only from lysates of activated T cells. Nevertheless, the GST-CrkII-SH2 fusion protein was unable to mediate direct association with p85 from lysates of either resting or activated T cells. Our results support a model in which T cell activation dependent conformational changes in CrkII and/or p85 promote an initial direct or indirect low affinity interaction between the two molecules, which is then stabilized by a secondary high affinity interaction mediated by direct binding of the CrkII-SH3(N) to the p85-PBP domain.

Protein kinase Ctheta: a new essential superstar on the T-cell stage.

Recent studies have identified protein kinase Cθ (PKCtheta), a member of the Ca(2+)-independent PKC family, as an essential component of the T-cell synapse that cooperates with calcineurin to activate the interleukin-2 (IL-2) gene. Several selective functions of PKCtheta involved in the activation and survival of T cells are reviewed herein. Among these, the nuclear factor-kappaB (NF-kappaB) signaling cascade appears to be the most critical target of PKCtheta in the T-cell receptor/CD28 costimulatory pathway that leads to T-cell activation.

Lck protein tyrosine kinase is a key regulator of T-cell activation and a target for signal intervention by Herpesvirus saimiri and other viral gene products.

Protein tyrosine kinases (PTKs) are critically involved in signaling pathways that regulate cell growth, differentiation, activation, and transformation. It is not surprising, therefore, that viruses acquire effector molecules targeting these kinases to ensure their own replication and/or persistence. This review summarizes our current knowledge on Lck, a member of the Src family of PTK, and its viral interaction partners. Lck plays a key role in T lymphocyte activation and differentiation. It is associated with a variety of cell surface receptors and is critical for signal transduction from the T-cell antigen receptor (TCR). Consequently, Lck is targeted by regulatory proteins of T-lymphotropic viruses, especially by the Herpesvirus saimiri (HVS) tyrosine kinase interacting protein (Tip). This oncoprotein physically interacts with Lck in HVS transformed T cells and has an impact on its catalytic activity. However, while Tip inhibits Lck activity in stably expressing cell lines, opposite effects were observed in several in vitro systems. At least in part, this complex situation may be related to the bipartite nature of the interaction surface of the two proteins. Studies on the interrelationships between Lck and its viral partners contribute to the understanding of the mechanisms of T-cell growth regulation, in general, and of viral pathogenicity in particular. In addition, understanding the regulation of Lck activity by viral proteins may serve as a basis for the development of new drugs capable of modifying Lck activity in different pathological situations.

Inhibition of the c-Jun N-terminal kinase/AP-1 and NF-kappaB pathways by PICOT, a novel protein kinase C-interacting protein with a thioredoxin homology domain.

Protein kinase C-theta (PKCtheta) is a Ca(2+)-independent PKC isoform that is selectively expressed in T lymphocytes (and muscle), and is thought to play an important role in T cell receptor-induced activation. To gain a better understanding of the function and regulation of PKCtheta, we have employed the yeast two-hybrid system to identify PKCtheta-interacting proteins. We report the isolation and characterization of a cDNA encoding a novel 335-amino acid (37. 5-kDa) PKCtheta-interacting protein termed PICOT (for PKC-interacting cousin of thioredoxin). PICOT is expressed in various tissues, including in T cells, where it colocalizes with PKCtheta. PICOT displays an N-terminal thioredoxin homology domain, which is required for the interaction with PKC. Comparison of the unique C-terminal region of PICOT with expressed sequence tag data bases revealed two tandem repeats of a novel domain that is highly conserved from plants to mammals. Transient overexpression of full-length PICOT (but not its N- or C-terminal fragments) in T cells inhibited the activation of c-Jun N-terminal kinase (but not extracellular signal-regulated kinase), and the transcription factors AP-1 or NF-kappaB. These findings suggest that PICOT and its evolutionary conserved homologues may interact with PKC-related kinases in multiple organisms and, second, that it plays a role in regulating the function of the thioredoxin system.

T cell activation stimulates the association of enzymatically active tyrosine-phosphorylated ZAP-70 with the Crk adapter proteins.

Engagement of the T cell antigen receptor initiates signal transduction involving tyrosine phosphorylation of multiple effector molecules and the formation of multimolecular complexes at the receptor site. Adapter proteins that possess SH2 and SH3 protein-protein interaction domains are implicated in the assembly of cell activation-induced signaling complexes. We found that Crk adapter proteins undergo activation-induced interaction with the zeta-chain associated protein (ZAP-70) tyrosine kinase in the human T cell line, Jurkat. Incubation of various glutathione S-transferase fusion proteins with a lysate of activated Jurkat cells resulted in selective association of ZAP-70 with Crk, but not Grb2 or Nck, adapter proteins. In addition, tyrosine-phosphorylated ZAP-70 co-immunoprecipitated with Crk from a lysate of activated Jurkat cells, and ZAP-70 association with GST-Crk was observed in a lysate of activated human peripheral blood T cells. Association between the two molecules was mediated by direct physical interaction and involved the Crk-SH2 domain and phosphotyrosyl-containing sequences on ZAP-70. The association required intact Lck, considered to be an upstream regulator of ZAP-70, because it could not take place in activated JCaM1 cells, which express normal levels of ZAP-70 but are devoid of Lck. Finally, glutathione S-transferase-Crk fusion proteins were found to interact predominantly with membrane-residing tyrosine-phosphorylated ZAP-70 that exhibited autophosphorylation activity as well as phosphorylation of an exogenous substrate, CFB3. These findings suggest that Crk adapter proteins play a role in the early activation events of T lymphocytes, apparently, by direct interaction with, and regulation of, the membrane-residing ZAP-70 protein tyrosine kinase.

Protein kinase C-theta (PKCtheta) distribution analysis in hematopoietic cells: proliferating T cells exhibit high proportions of PKCtheta in the particulate fraction.

A comparative analysis of protein kinase C-theta (PKCtheta) protein expression was performed in various mouse organs and tissues, freshly isolated populations of mouse and human hematopoietic cells, primary leukemias, and established cell lines of different histological origins. Results demonstrated a predominant expression of PKCtheta in lymphoid tissues and skeletal muscle. Expression levels of PKCtheta, as well as PKCalpha, delta, epsilon, zeta, and eta in the thymus, were not markedly changed during postnatal development. High levels of expression were observed in CD4(+) and CD8(+) single-positive T cells and CD4(+)CD8(+) double-positive thymocytes, while B cells were completely devoid of PKCtheta. PKCtheta was found also in platelets, but relatively low levels or no detection of PKCtheta expression were observed in neutrophils, monocytes, and macrophages. Highly proliferating leukemic T cells of established lines or primary tumors, but not freshly isolated resting peripheral blood T cells, exhibited high levels of membrane-bound PKCtheta. Increased proportions of PKCtheta in the particulate fraction was not restricted to malignant cells but correlated with the extent of proliferation of the T cells. Thus, human peripheral blood T cells that were induced to proliferate by exposure to mitogen and IL-2 expressed increased levels of PKCtheta in the particulate fraction. Significantly lower proportions of membrane-bound PKC were observed for five other isoenzymes expressed in T cells. The occurrence of PKCtheta in T, but not B, cells and its subcellular distribution in proliferating cells implicate PKCtheta in cellular mechanisms regulating the sustained proliferation of T cells.

ITAMs: immunoregulatory scaffolds that link immunoreceptors to their intracellular signaling pathways.

Antigen receptors on the surface of T and B lymphocytes and various immunoglobulin Fc receptors are complexed multi-subunit structures that possess unique cytoplasmic modules, termed immunoreceptor tyrosine-based activation motif (ITAM). These modules consist of two repeats of the conserved sequence Tyr-X-X-Leu/lle spaced by six-to-eight residues and they function as 'on and off' switches that link the receptors to their intracellular signaling machinery. Thus, engagement of ITAM-containing receptors results in a rapid and transient phosphorylation of the ITAMs' tyrosine residues that function as temporal scaffolds for Src homology 2 (SH2) domains of downstream effector molecules. Recruitment and binding of these molecules to phospho-ITAMs initiate a cascade of biochemical events that lead to cell proliferation, differentiation, and acquisition of unique effector functions.

New perspectives on PKCtheta, a member of the novel subfamily of protein kinase C.

Members of the protein kinase C (PKC) family of serine/threonine protein kinases have been implicated in numerous cellular responses in a large variety of cell types. Expression patterns of individual members and differences in their cofactor requirements and potential substrate specificity suggest that each isoenzyme may be involved in specific regulatory processes. The PKCtheta isoenzyme exhibits a relatively restricted expression pattern with high protein levels found predominantly in hematopoietic cells and skeletal muscle. PKCtheta was found to be expressed in T, but not B lymphocytes, and to colocalize with the T-cell antigen receptor (TCR) at the site of contact between the antigen-responding T cell and the antigen-presenting cell (APC). Colocalization of PKCtheta with the TCR was selective for this isoenzyme and occurred only upon antigen-mediated responses leading to T-cell activation and proliferation. PKCtheta was found to be involved in the regulation of transcriptional activation of early-activation genes, predominantly AP-1, and its cellular distribution and activation were found to be regulated by the 14-3-3 protein. Other findings indicated that PKCtheta can associate with the HIV negative factor (Nef) protein, suggesting that altered regulation of PKCtheta by Nef may contribute to the T-cell impairments that are characteristic of infection by HIV. PKCtheta is expressed at relatively high levels in skeletal muscle, where it is suggested to play a role in signal transduction in both the developing and mature neuromuscular junction. In addition, PKCtheta appears to be involved in the insulin-mediated response of intact skeletal muscle, as well as in experimentally induced insulin resistance of skeletal muscle. Further studies suggest that PKCtheta is expressed in endothelial cells and is involved in multiple processes essential for angiogenesis and wound healing, including the regulation of cell cycle progression, formation and maintenance of actin cytoskeleton, and formation of capillary tubes. Here, we review recent progress in the study of PKCtheta and discuss its potential role in various cellular responses.

Posttranslational regulation of Lck and a p36-38 protein by activators of protein kinase C: differential effects of the tumor promoter, PMA, and the non-tumor-promoter, bryostatin.

T cell activation via the antigen receptor or by PKC-activating drugs results in phosphorylation of Lck and alteration of its electrophoretic mobility. Although tyrosine phosphorylation appears to regulate Lck enzymatic activity, the significance of phosphorylation of serine residues and its relevance to the cell proliferation process are yet unclear. We found that the PKC activator, bryostatin, like PMA, induced the conversion of p56lck to a slower migrating form with an apparent molecular mass of 60 kDa. The effect of PMA lasted over 48 hr but that of bryostatin was transient and correlated in time kinetics with that of the bryostatin-induced degradation of PKC. The effects of bryostatin were dominant over those of PMA. In addition, PKC was found to affect both serine and tyrosine phosphorylation of Lck but had no significant effect on the in vitro catalytic activity of Lck. To test whether serine phosphorylation of Lck may affect its ability to bind tyrosine phosphoproteins, we compared Lck immunoprecipitates from PMA- and bryostatin-treated T cells. We found that a 36- to 38-kDa tyrosine phosphoprotein co-immunoprecipitated with Lck from cells that were treated for 24 hr with PMA, but not bryostatin. A p36-38 from PMA- but not bryostatin-treated cells also interacted with an Lck-SH2 fusion protein, suggesting differential regulation of p36-38 by PMA and bryostatin. Furthermore, in vitro phosphorylation of p36-38 occurred in lysates of cells that were treated for 24 hr with PMA, but not in lysates of bryostatin-treated cells. The results show that tyrosine phosphorylation and the association of p36-38 with Lck are differentially affected by bryostatin and PMA and suggest that PKC regulates the interaction of potential signaling molecules with Lck, thereby regulating biochemical events that are relevant to T cell mitogenesis and/or transformation.

ITIMs and ITAMs. The Yin and Yang of antigen and Fc receptor-linked signaling machinery.

The initial stages of an immune response are regulated at the level of the cell-surface antigen and Fc receptors. The extracellular portions of these receptors provide immune specificity and determine the nature of the responding effector cells, whereas the intracellular portion transduces signals into the cell and determines the intensity and duration of the immune response. Recent studies led to the identification of two types of modules within the cytoplasmic region of receptor subunits that are critical for the activation and termination of signal transduction pathways. Phosphorylation of the conserved tyrosine residues within the two modules, the immunoreceptor tyrosine-based activation motif (ITAM) and the immunoreceptor tyrosine-based inhibition motif (ITIM), is followed by the recruitment of different sets of SH2-containing molecules to the receptor site. These proteins regulate the receptor-linked signal transduction pathways in a positive or a negative fashion, which is a reminiscent of the ancestral Yin-Yang principle.

Immunoreceptor tyrosine-based activation motif (ITAM), a unique module linking antigen and Fc receptors to their signaling cascades.

Signal transduction by the T cell and B cell antigen receptors and by receptors for a variety of immunoglobulins' Fc region is strictly dependent on a receptor subunit cytoplasmic module termed immunoreceptor tyrosine-based activation motif (ITAM). This module exists in one or more copies in each of the receptor-associated signal-transducing molecules and it possesses two repeats of the consensus sequence Tyr-X-X-Leu/Ile spaced by six to eight amino acids. Receptor engagement is followed by a rapid and transient phosphorylation of tyrosine residues within their ITAMs, thereby creating temporary binding sites for Src homology 2 (SH2)-containing signaling molecules operating downstream of the activated receptor. The purpose of this review is to discuss recent findings on the functional role of ITAMs in antigen and Fc receptor-mediated signal transduction, with a particular emphasis on kinases operating upstream and downstream of the ITAMs.