ABSTRACT
BACKGROUND: Infusion of high-dose intravenous methotrexate (MTX) has been demonstrating to penetrate the blood-brain barrier. The aim of this present study was to assess the efficacy and safety of high dose MTX in patients with central nervous system (CNS) metastases of breast cancer. METHODS: Twenty-two patients with CNS metastases treated by MTX (3 g/m2) between April 2004 and October 2009 were enrolled. Clinical response rate, time to progression (TTP), overall survival (OS), and safety were assessed. RESULTS: In terms of brain metastases, 2 patients (9%) achieved a partial response, 10 patients (45%) had disease stabilization, and 10 patients (45%) had disease progression. In others metastatic sites, 7 patients (39%) achieved a disease stabilization, and 11 patients (61%) had disease progression. TTP and OS were 2.1 (95%CI 1.4-2.9) and 6.3 (95%CI 1.8-10) months, respectively. CONCLUSION: High-dose MTX demonstrated a moderate activity at 3 g/m2. Nonetheless, the favorable toxicity profile should suggest the possibility to increase the dosage and further study are planned.
Subject(s)
Antineoplastic Agents/therapeutic use , Breast Neoplasms/drug therapy , Central Nervous System Neoplasms/drug therapy , Methotrexate/therapeutic use , Administration, Intravenous , Adult , Aged , Aged, 80 and over , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Central Nervous System Neoplasms/mortality , Central Nervous System Neoplasms/secondary , Drug Administration Schedule , Drug Dosage Calculations , Female , Humans , Middle Aged , Neoplasm Metastasis , Survival AnalysisABSTRACT
El carcinoma de células renales es la octava neoplasia maligna más frecuente en el adulto y la más frecuente del riñón. Es, por tanto, una enfermedad muy común para el radiólogo. El objetivo de esta revisión es hacer una aproximación general a las diferentes técnicas de imagen utilizadas para diagnosticar, caracterizar y ayudar a planificar el tratamiento del carcinoma de células renales, así como hacer consideraciones básicas sobre la estadificación, el tratamiento percutáneo guiado con técnicas de imagen y el seguimiento en las situaciones clínicas más habituales (AU)
Renal cell carcinoma is the eighth most common malignancy in adults and the most common malignancy in the kidney. It is thus a very common disease for radiologists. This review aims to provide a general overview of the imaging techniques used to diagnose, characterize, and help plan the treatment of renal cell carcinoma as well as to review basic aspects related to staging, imaging-guided percutaneous treatment, and follow-up in the most common clinical scenarios (AU)
Subject(s)
Humans , Male , Female , Carcinoma , Kidney Neoplasms , Carcinoma, Renal Cell , Diagnostic Imaging/instrumentation , Diagnostic Imaging/methods , Diagnostic Imaging , Positron-Emission Tomography/instrumentation , Positron-Emission Tomography/methods , Neoplasm Staging/instrumentation , Neoplasm Staging/methods , Neoplasm Staging/trends , Diagnostic Imaging/trends , LeiomyomatosisABSTRACT
Renal cell carcinoma is the eighth most common malignancy in adults and the most common malignancy in the kidney. It is thus a very common disease for radiologists. This review aims to provide a general overview of the imaging techniques used to diagnose, characterize, and help plan the treatment of renal cell carcinoma as well as to review basic aspects related to staging, imaging-guided percutaneous treatment, and follow-up in the most common clinical scenarios.
Subject(s)
Carcinoma, Renal Cell/diagnosis , Diagnostic Imaging , Kidney Neoplasms/diagnosis , Carcinoma, Renal Cell/therapy , Humans , Kidney Neoplasms/therapy , Neoplasm StagingABSTRACT
BACKGROUND: The study's objective was to assess the predictive factors of anemia induced by chemotherapy in early breast cancer patients. PATIENTS AND METHODS: Patients treated by adjuvant or neo-adjuvant anthracyclin-based regimens with or without taxanes between 1998 and 2006 in a French university hospital were studied. Chemotherapy included. Anemia was defined as a hemoglobin (Hb) concentration lower than 12 g/dL. Multivariate analysis by logistic regression was used to search for baseline risk factors linked to the occurrence of anemia. RESULTS: Among 378 patients, anemia was observed in 64% of cases. The occurrence of anemia was significantly related to 6 risk factors: exposure to taxanes (HR 11.5, 95% CI, 2.5-52.6), high dose of anthracyclin (epirubicin 100 mg/m²)(HR 4.3; 95% CI, 2.8-8), Hb at baseline < 13.5 g/d (HR 4.3; 95% CI, 2.6-7.1), mastectomy (HR 2.5; 95% CI, 1.4-3.3), age >60 (HR 2.5; 95% CI, 1.4-5) years old (HR 2.5; 95% CI, 1.4-5) and Body Mass Index (BMI) ≤ 25 kg/m² (HR 1.7; 95% CI, 1.0-2.8). CONCLUSION: Taking into account the following factors: type of chemotherapy, BMI, age, Hb at baseline should allow a better identification of patients at risk of anemia.
Subject(s)
Anemia/chemically induced , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Breast Neoplasms/drug therapy , Adult , Age Factors , Anemia/blood , Anemia/epidemiology , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/adverse effects , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Biomarkers/blood , Body Mass Index , Breast Neoplasms/surgery , Chemotherapy, Adjuvant/adverse effects , Cyclophosphamide/adverse effects , Cyclophosphamide/therapeutic use , Docetaxel , Doxorubicin/adverse effects , Doxorubicin/therapeutic use , Drug Administration Schedule , Epirubicin/administration & dosage , Epirubicin/adverse effects , Female , Hemoglobins/metabolism , Humans , Incidence , Logistic Models , Mastectomy , Middle Aged , Multivariate Analysis , Retrospective Studies , Risk Factors , Taxoids/administration & dosage , Taxoids/adverse effectsSubject(s)
Antineoplastic Agents/pharmacokinetics , Carcinoma, Renal Cell/therapy , Indoles/pharmacokinetics , Kidney Neoplasms/therapy , Mediastinal Neoplasms/drug therapy , Pancreatic Neoplasms/drug therapy , Pyrroles/pharmacokinetics , Renal Dialysis , Antineoplastic Agents/administration & dosage , Carcinoma, Renal Cell/metabolism , Carcinoma, Renal Cell/pathology , Carcinoma, Renal Cell/surgery , Drug Monitoring , Humans , Indoles/administration & dosage , Kidney Neoplasms/metabolism , Kidney Neoplasms/pathology , Kidney Neoplasms/surgery , Male , Mediastinal Neoplasms/metabolism , Mediastinal Neoplasms/secondary , Middle Aged , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/secondary , Pyrroles/administration & dosage , SunitinibABSTRACT
UNLABELLED: This Phase II trial investigated the combination paclitaxel (P) and uracil-tegafur (UFT) in patients with metastatic breast cancer (MBC). METHODS: Main eligibility criteria included HER-2 negative MBC, ECOG performance status of 0-2, exposure to 1-2 prior chemotherapy regimen in the metastatic setting, previous exposure to an anthracycline containing regimen either at metastatic or adjuvant setting. Each 35-day cycle consisted of P at 80 mg/m(2) by intravenous infusion on days 1, 8, 15, 22 and 29 and oral UFT at 300 mg/m(2) TID (three time a day) from days 1-28 and oral folinic acid at 90 mg QD (one a day). RESULTS: Between March 2003 and December 2007, 31 patients were enrolled. Median age was 66 years (range 44-78). All tumours were HER-2 negative and 7% were triple negative (ER, PgR, HER-2). The majority of patients had visceral disease (81%). All patients had received an anthracycline containing regimen and 74% had a previous docetaxel containing treatment. Median of 4 and 3 cycles of P and UFT were administered with a relative dose intensity of 85.3% and 94.3%, respectively. Twelve (40%)(95% CI: 22.5-57.5) confirmed ORR were observed. Stable and progression disease were reported in 43% and 17% of cases. Median Response duration was 8.4 month (95% CI: 4.9-11.7), median Time to progression was 9.5 months (95% CI: 6.6-13.8) and median Overall Survival was 23.5 months (95% CI: 16.8-37.2). Thirteen pts (43%) experienced a grade 3 or 4 adverse events (AEs): One death occurred related to the study drugs (febrile neutropenia). Chemotherapy was discontinued due to toxicity in 30% of pts CONCLUSIONS: Accrual was closed in January 2008 due to concerns regarding the degree and accumulative nature of AEs. Nonetheless, the ORR is encouraging and warranted further studies with adapted doses and schedules.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Breast Neoplasms/drug therapy , Paclitaxel/administration & dosage , Aged , Antineoplastic Agents, Phytogenic/administration & dosage , Antineoplastic Agents, Phytogenic/adverse effects , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Breast Neoplasms/pathology , Drug Administration Schedule , Female , Humans , Maximum Tolerated Dose , Middle Aged , Neoplasm Metastasis , Paclitaxel/adverse effects , Tegafur/administration & dosage , Tegafur/adverse effects , Treatment Outcome , Uracil/administration & dosage , Uracil/adverse effectsABSTRACT
BACKGROUND: One can consider as a standard neoadjuvant treatment for breast cancer, the sequence of 4 cycles of anthracycline-based chemotherapy followed by 4 cycles of docetaxel. Based on the belief that the sequence order between anthracycline and taxane might be of interest, this study assessed the impact of the sequence order. METHODS: One hundred and twenty three patients with breast cancer were treated with neoadjuvant chemotherapy in 5 oncologic centers between 2003 and 2007. This study compared 65 patients treated with 4 cycles of docetaxel followed by 4 cycles of anthracycline-based chemotherapy (cohort T), versus another cohort of 58 patients treated with 4 cycles of anthracycline-based chemotherapy followed by 4 cycles of docetaxel (cohort A). RESULTS: The overall dose intensity of docetaxel and clinical complete responses were significantly higher in cohort T. No statistically significant differences were observed in terms of conservative surgeries or histological responses. The sequence of chemotherapy did not significantly influence other treatment-related toxicities. Mild neurotoxicity was higher in patients treated in cohort T. Anemias (≥Grade 1) were higher in cohort A (52% versus 81%; p = 0.0008). CONCLUSION: The present study failed to identify an impact of the sequence of taxane administration on the efficacy. Nevertheless, starting neoadjuvant chemotherapy by taxane reduces the occurrence of anemia. These findings might allow a selection of the sequence order based on the toxicity profile.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Breast Neoplasms/drug therapy , Neoadjuvant Therapy/methods , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Breast Neoplasms/surgery , Cyclophosphamide/administration & dosage , Disease-Free Survival , Docetaxel , Doxorubicin/administration & dosage , Epirubicin/administration & dosage , Female , Fluorouracil/administration & dosage , Humans , Kaplan-Meier Estimate , Logistic Models , Middle Aged , Proportional Hazards Models , Retrospective Studies , Taxoids/administration & dosage , Treatment OutcomeABSTRACT
Preoperative examination intended to detect multifocality, multicentricity and bilaterality-once considered the strongest indication of breast magnetic resonance imaging (MRI)-is currently being strongly questioned in medical literature. This paper aims at evaluating, based on our experience at Clínica Alemana, Santiago, Chile, breast MRI ability to improve preoperative radiological tumour staging by conventional methods, as well as to determine the proportion of patients in which this diagnostic procedure generated changes in the surgical management. We retrospectively reviewed preoperative MRI studies carried out between January 2009 and June 2010. Classification: Group 1: MRI provided no new information. Group 2: by detecting additional lesions, MRI improved radiological staging without changing the type of surgery planned. Group 3: MRI showed new benign lesions and caused unnecessary surgery. Group 4: MRI successfully changed the type of surgery planned based on conventional studies. A total of 419 breast MRI scans were performed during a 18-month period; 39 percent of them were carried out preoperatively. For the analysis, 128 patients were enrolled and distributed in the following categories: Group 1 (66 percent), Group 2 (20 percent), Group 3 (2 percent) and Group 4 (12 percent). In 95.3 percent of the patients, a single surgery with clear margins was performed. This work demonstrated the usefulness of preoperative MRI in our practice, i.e., it allowed for a better radiological staging in one third of the patients and even successfully changed the surgical approach in 12 percent of cases.
El estudio preoperatorio en búsqueda de multifocalidad, multicentricidad y bilateralidad -antes considerada la indicación más sólida de la resonancia magnética (RM) mamaria- hoy se encuentra fuertemente cuestionada en la literatura. En este trabajo nos propusimos evaluar la capacidad de la RM mamaria en nuestro centro para mejorar la etapificación radiológica preoperatoria realizada por métodos convencionales y determinar la proporción de las pacientes en que genera cambio en el enfoque quirúrgico. Hemos revisado retrospectivamente las RM preoperatorias entre enero de 2009 y junio de 2010. Clasificación: Grupo1: la RM no aportó información nueva. Grupo 2: al detectar lesiones adicionales, mejoró la etapificación radiológica, sin cambiar el tipo de la cirugía planificada. Grupo3: demostró nuevas lesiones no malignas y causó cirugía inútil. Grupo 4: cambió correctamente el tipo de cirugía planeada en base a los estudios convencionales. En los 18 meses se realizaron 419 RM mamarias, el 39 por ciento de ellas en preoperatorio. Para el análisis se han reclutado 128 pacientes con la siguiente distribución en los grupos predeterminados: Grupo 1(66 por ciento), Grupo 2(20 por ciento), Grupo 3(2 por ciento) y Grupo 4(12 por ciento). En el 95,3 por ciento de las pacientes se logró realizar una sola cirugía con márgenes libres. Este trabajo demostró la utilidad de la RM preoperatoria en nuestra práctica: permite una mejor etapificación radiológica en el tercio de las pacientes e incluso cambia correctamente el enfoque quirúrgico en el 12 por ciento de los casos.
Subject(s)
Humans , Female , Adult , Middle Aged , Aged, 80 and over , Preoperative Care/methods , Magnetic Resonance Imaging/methods , Mastectomy/methods , Breast Neoplasms/pathology , Neoplasm Staging/methods , Retrospective Studies , Neoplasm Invasiveness , Mammography , Breast Neoplasms/surgeryABSTRACT
ADP-ribosyltransferases (ADPRTs) form an interesting class of enzymes with well-established roles as potent bacterial toxins and metabolic regulators. ADPRTs catalyze the transfer of the ADP-ribose moiety from NAD(+) onto specific substrates including proteins. ADP-ribosylation usually inactivates the function of the target. ADPRTs have become adapted to function in extra- and intracellular settings. Regulation of ADPRT activity can be mediated by ligand binding to associated regulatory domains, proteolytic cleavage, disulphide bond reduction, and association with other proteins. Crystallisation has revealed a conserved core set of elements that define an unusual minimal scaffold of the catalytic domain with remarkably plastic sequence requirements--only a single glutamic acid residue critical to catalytic activity is invariant. These inherent properties of ADPRTs suggest that the ADPRT catalytic fold is an attractive, malleable subject for protein design.
Subject(s)
Poly(ADP-ribose) Polymerases/chemistry , Poly(ADP-ribose) Polymerases/metabolism , Amino Acid Sequence , Animals , Biotechnology , Drug Design , Humans , Ligands , Models, Molecular , Molecular Sequence Data , Poly(ADP-ribose) Polymerases/genetics , Protein Conformation , Protein Folding , Proteins/antagonists & inhibitors , Proteins/metabolism , Sequence Homology, Amino Acid , Substrate SpecificityABSTRACT
Toll-like receptors (TLRs) are ancient microbial pattern recognition receptors highly conserved from Drosophila to humans. To investigate if subsets of human dendritic cell precursors (pre-DC), including monocytes (pre-DC1), plasmacytoid DC precursors (pre-DC2), and CD11c(+) immature DCs (imDCs) are developed to recognize different microbes or microbial antigens, we studied their TLR expression and responses to microbial antigens. We demonstrate that whereas monocytes preferentially express TLR 1, 2, 4, 5, and 8, plasmacytoid pre-DC strongly express TLR 7 and 9. In accordance with these TLR expression profiles, monocytes respond to the known microbial ligands for TLR2 (peptidoglycan [PGN], lipoteichoic acid) and TLR4 (lipopolysaccharide), by producing tumor necrosis factor (TNF)-alpha and interleukin (IL)-6. In contrast, plasmacytoid pre-DCs only respond to the microbial TLR9-ligand, CpG-ODNs (oligodeoxynucleotides [ODNs] containing unmethylated CpG motifs), by producing IFN-alpha. CD11c(+) imDCs preferentially express TLR 1, 2, and 3 and respond to TLR 2-ligand PGN by producing large amounts of TNF-alpha, and to viral double-stranded RNA-like molecule poly I:C, by producing IFN-alpha and IL-12. The expression of distinct sets of TLRs and the corresponding difference in reactivity to microbial molecules among subsets of pre-DCs and imDCs support the concept that they have developed through distinct evolutionary pathways to recognize different microbial antigens.
Subject(s)
Dendritic Cells/metabolism , Drosophila Proteins , Hematopoietic Stem Cells/metabolism , Membrane Glycoproteins/genetics , Receptors, Cell Surface/genetics , Biomarkers , Cytokines/biosynthesis , Dendritic Cells/cytology , Dendritic Cells/drug effects , Dendritic Cells/immunology , Gene Expression , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/drug effects , Hematopoietic Stem Cells/immunology , Humans , Lipopolysaccharides/immunology , Lipopolysaccharides/pharmacology , Monocytes/cytology , Monocytes/metabolism , Oligodeoxyribonucleotides/immunology , Staphylococcus aureus/immunology , Toll-Like Receptor 1 , Toll-Like Receptor 2 , Toll-Like Receptor 4 , Toll-Like Receptor 7 , Toll-Like Receptor 9 , Toll-Like ReceptorsABSTRACT
Nuclear Factor of Activated T cell (NFAT) is a family of transcription factors that are important for the coordinate expression of various cytokines and immunoregulatory cell surface molecules in T cells and other types of cells in the immune system. In addition, analysis of gene disrupted mice revealed that some members of NFAT family are important for the development of myocardium, myocardial hypertrophy, and mesenchymal stem cells. NFAT family proteins have two conserved domains, the NFAT Homology Domain (NHD) and the Rel Similarity Domain (RSD). The RSD is DNA binding and AP-1 interacting domain which has structural similarity to the Rel Homology Region, the DNA binding domain of Rel family proteins. The NHD is a regulatory domain required for the Ca regulated translocation of NFAT. We report here the isolation and initial characterization of a novel RSD containing protein designated NFATz. NFATz has a RSD but no NHD. NFATz protein is localized in the nucleus without Ca signal. There is no detectable binding to a typical NFAT site even in the presence of AP-1, and it is not capable of activating transcription through the NFAT site. The chromosomal location determined by FISH revealed that NFATz and NFATx genes are in the same region.
Subject(s)
DNA-Binding Proteins/chemistry , DNA-Binding Proteins/genetics , Nuclear Proteins , Proto-Oncogene Proteins c-rel/chemistry , Transcription Factors/chemistry , Transcription Factors/genetics , Amino Acid Sequence , Animals , Base Sequence , Calcium/pharmacology , Cell Line , Cell Nucleus/chemistry , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Chromosomes, Human, Pair 16/genetics , Cloning, Molecular , DNA/genetics , DNA/metabolism , DNA-Binding Proteins/metabolism , Gene Expression Profiling , Humans , Mice , Molecular Sequence Data , NFATC Transcription Factors , Phylogeny , Physical Chromosome Mapping , Protein Binding , Protein Structure, Tertiary , RNA, Messenger/analysis , RNA, Messenger/genetics , Response Elements/genetics , Sequence Homology, Amino Acid , Transcription Factor AP-1/metabolism , Transcription Factors/metabolism , Transcriptional Activation/geneticsABSTRACT
Signaling through the hematopoietic receptors requires activation of receptor-associated Janus (Jak) kinases. For example, Jak1 and Jak3 bind specifically to the IL-2 receptor beta (IL-2Rbeta) and common gamma (gammac) chains, respectively, and initiate biochemical signals critical in controlling immune responses. The region of Jak responsible for receptor interactions, however, is not well characterized. Here we describe a naturally occurring Jak3 mutation from a patient with autosomal severe combined immunodeficiency (SCID), where a single amino acid substitution, Y100C, in Janus homology domain 7 (JH7) prevents kinase-receptor interaction. This mutation also results in a loss of IL-2-induced signaling in a B-cell line derived from this patient. Using mutational analysis we have identified a region of Jak3, including portions of JH6 and JH7, that is sufficient for kinase-receptor contact and show that this segment interacts with the proline-rich Box1 region of the receptor. Furthermore, a Jak3-Jak1 chimera containing only the JH6 and JH7 domains of Jak3 interacts with gammac and can reconstitute IL-2-dependent responses, including receptor phosphorylation and activation of signal transducer and activator of transcription (STAT) 5b. Our results suggest that the N-terminus of Jak kinases is critical for receptor binding, and is therefore likely to determine specificity of Jak kinase-receptor interactions.
Subject(s)
Point Mutation , Protein-Tyrosine Kinases/genetics , Severe Combined Immunodeficiency/genetics , Cell Line , Humans , Janus Kinase 1 , Janus Kinase 3 , Polymerase Chain Reaction , Protein Binding , Protein-Tyrosine Kinases/metabolism , Receptors, Interleukin-2/genetics , Receptors, Interleukin-2/physiology , Recombinant Fusion Proteins/metabolism , Severe Combined Immunodeficiency/enzymology , TransfectionABSTRACT
In these studies, IFN gamma-inducing factor (IGIF), unlike IL-12, did not drive Th1 development in BALB/c or C57BL/6 mice, but like IL-1alpha, potentiated IL-12-driven Th1 development in BALB/c mice. IGIF and IL-12 synergized for IFN gamma production from Th1 cells. Unlike IL-1alpha, IGIF had no effect on Th2 cells. IGIF signaled through IRAK, IL-1 receptor-associated kinase, to induce nuclear translocation of p65/p50 NFkappaB in Th1 cells. IL-1alpha had no effect on proliferation, cytokine production, or NFkappaB activation in Th1 cells but activated NFkappaB and proliferation in Th2 cells. Thus, Th1 and Th2 cells may differ in responsiveness and receptor expression for IL-1 family molecules. IGIF and IL-1alpha may differentially amplify Th1 and Th2 effector responses, respectively.
Subject(s)
Cytokines/physiology , Interferon-gamma/biosynthesis , Interleukin-12/physiology , Leukopoiesis , Protein Kinases/metabolism , Th1 Cells/cytology , Animals , Antigen-Presenting Cells/immunology , CD3 Complex/physiology , Cytokines/administration & dosage , DNA-Binding Proteins/metabolism , Drug Synergism , Enzyme Activation , Interferon Inducers/administration & dosage , Interleukin-1/pharmacology , Interleukin-1 Receptor-Associated Kinases , Interleukin-12/administration & dosage , Interleukin-18 , Lymphocyte Activation/drug effects , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Transgenic , NF-kappa B/physiology , STAT4 Transcription Factor , Signal Transduction , Th2 Cells/physiology , Trans-Activators/metabolismABSTRACT
Mono-ADP-ribosylation is one of the posttranslational protein modifications regulating cellular metabolism, e.g., nitrogen fixation, in prokaryotes. Several bacterial toxins mono-ADP-ribosylate and inactivate specific proteins in their animal hosts. Recently, two mammalian GPI-anchored cell surface enzymes with similar activities were cloned (designated ART1 and ART2). We have now identified six related expressed sequence tags (ESTs) in the public database and cloned the two novel human genes from which these are derived (designated ART3 and ART4). The deduced amino acid sequences of the predicted gene products show 28% sequence identity to one another and 32-41% identity vs the muscle and T cell enzymes. They contain signal peptide sequences characteristic of GPI anchorage. Southern Zoo blot analyses suggest the presence of related genes in other mammalian species. By PCR screening of somatic cell hybrids and by in situ hybridization, we have mapped the two genes to human chromosomes 4p14-p15.1 and 12q13.2-q13.3. Northern blot analyses show that these genes are specifically expressed in testis and spleen, respectively. Comparison of genomic and cDNA sequences reveals a conserved exon/intron structure, with an unusually large exon encoding the predicted mature membrane proteins. Secondary structure prediction analyses indicate conserved motifs and amino acid residues consistent with a common ancestry of this emerging mammalian enzyme family and bacterial mono(ADP-ribosyl)transferases. It is possible that the four human gene family members identified so far represent the "tip of an iceberg," i.e., a larger family of enzymes that influences the function of target proteins via mono-ADP-ribosylation.
Subject(s)
ADP Ribose Transferases/genetics , Adenosine Diphosphate Ribose/metabolism , Bacterial Toxins/genetics , Chromosomes, Human, Pair 4 , Membrane Proteins/genetics , Amino Acid Sequence , Bacterial Toxins/metabolism , Chromosome Mapping , Chromosomes, Human, Pair 12 , Cloning, Molecular , GPI-Linked Proteins , Humans , Male , Molecular Sequence Data , Multigene Family , Sequence Homology, Amino Acid , Spleen/metabolism , Testis/metabolismABSTRACT
Bacteriophage T4 codes at least for two ADP-ribosylating activities, the 76 kDa Alt and the 24 kDa Mod gene products. The main target for both enzymes is the host RNA polymerase. We cloned and sequenced the alt gene and overexpressed the corresponding enzyme. The recombinant protein shows ADP-ribosylating activities in vitro, as had been described earlier for the native enzyme isolated from phage heads. The native as well as the recombinant protein ADP-ribosylate the alpha-subunit of RNA polymerase, but also subunits beta, beta' and sigma 70 and perform an autoribosylation reaction. Taking advantage of the pKWIII test system, constructed to measure promoter strengths in vivo, it was found that ADP-ribosylation of RNA polymerase leads to an increase of transcription from T4 early promoters up to a factor of two. In an infected host cell this should cause an enhanced expression of T4 genes. Depending on whether RNA polymerase was ADP-ribosylated or not, it initiated transcription at T4 promoters with different sequence characteristics: unribosylated RNA polymerase recognizes the early T4 promoters by an extended -10 region, whereas the ribosylated enzyme selects for T4 early promoters with an extended T4-specific and highly conserved -35 region. These results may reflect how the virus, step by step imposes its genetic program on the host cell, and in part they give a rationale for the extension of the consensus sequence observed with these promoters. We also sequenced the genomic region of the T4 mod gene and found two open reading frames coding both for proteins of approximately 24 kDa. Up to now none of the reading frames could be cloned into E. coli in an active form, making it highly probable that the ADP-ribosylation pattern inflicted by gene product Mod on host RNA polymerase is deleterious to these bacteria. Comparisons of the amino acid sequences showed significant homologies among the two reading frames. Computer analysis reveals that both Mod sequences and also the sequence of the Alt protein exhibit a structural concordance with the catalytic domains of other prokaryotic ADP-mono-ribosyltransferases such as the Pseudomonas aeruginosa exotoxin A, the cholera labile enterotoxin, the diphteria toxin, the heat labile enterotoxin A of E. coli, and pertussis toxin. We present a detailed model for T4 transcription regulation.
Subject(s)
Adenosine Diphosphate Ribose/metabolism , Bacteriophage T4/enzymology , Gene Expression Regulation, Viral , Poly(ADP-ribose) Polymerases/metabolism , Adenosine Diphosphate/metabolism , Amino Acid Sequence , Bacteriophage T4/genetics , Base Sequence , DNA, Viral , Molecular Sequence Data , Poly(ADP-ribose) Polymerases/chemistry , Poly(ADP-ribose) Polymerases/genetics , Poly(ADP-ribose) Polymerases/isolation & purification , Transcription, GeneticABSTRACT
We searched the database of expressed sequence tags (dbEST) for relatives of the known human and murine mono(ADP-ribosyl)transferases (mADPRT), poly(ADP-ribosyl)polymerases (PARP), ADP-ribosyl cyclases, and ADP-ribosylarginine hydrolases (ARH). By May 31, 1996, all of the known enzymes except for RT6 were represented in dbEST by exact sequence matches from mouse and/or human tissues. Several ESTs show significant sequence similarity but not identity to known mADPRTs. We isolated, cloned, and sequenced the corresponding genes. Our results show that seven human ESTs stem from a novel gene, provisionally designated LART, which is specifically expressed in lymphatic tissues. Five human ESTs stem from a novel gene, here designated TART1, which is specifically expressed in testis. This gene is also represented by a single mouse EST. One other mouse EST stems from a distinct gene, here designated TART2, which is also expressed in testis. These genes have similar exon/intron structures. The predicted LART and TART1 gene products contain hydrophobic N- and C-terminal signal peptides characteristic for GPI-anchored surface proteins, TART2 lacks the GPI-anchor signal peptide. The predicted native proteins show 28-42% sequence identity to one another. They each contain four cysteine residues that probably form conserved disulfide bonds. They each also contain a conserved glutamic acid residue within the proposed active site motif LART and TART1 show interesting deviations from the surrounding consensus sequence.
Subject(s)
ADP Ribose Transferases/genetics , DNA, Complementary , Databases, Factual , Poly(ADP-ribose) Polymerases , Animals , Base Sequence , Cloning, Molecular , Gene Expression , Humans , Mice , Molecular Sequence DataABSTRACT
Mono ADP-ribosylation is a posttranslational protein modification that has been implicated in the regulation of key biological functions in bacteria as well as in animals. Recently, the first cDNAs for eucaryotic mono(ADPribosyl)transferases were cloned and found to exhibit significant sequence similarity only to one other known protein, the T cell differentiation antigen Rt6. In this paper we describe secondary structure analyses of Rt6 and related proteins and show conserved structure motifs and amino acid residues consistent with a common ancestry of these eucaryotic proteins and bacterial ADP-ribosyltransferases. Moreover, we have expressed soluble mouse Rt6-1 and Rt6-2 gene products in which C-terminal tags (FLAG-His6) replace the native glycosylphosphatidylinositol anchor signal sequences. Purified recombinant Rt6-2, but not Rt6-1, shows NAD+ glycohydrolase activity, which is inhibited by the arginine analogue agmatine. Immunoprecipitation of recombinant Rt6-1 and Rt6-2 with anti-FLAG M2 antibody followed by incubation with [32P]NAD+ leads to rapid and covalent incorporation of radioactivity into the light chain of the M2 antibody. The bound label is resistant to treatment with HgCl2 but sensitive to NH2OH, characteristic of arginine-linked ADP-ribosylation. These results demonstrate that Rt6-1 and RT6-2 possess the enzymatic activities typical for NAD+-dependent arginine/protein mono(ADPribosyl)transferases (EC 2.4.2.31). They are the first such enzymes to be molecularly characterized in the immune system.
Subject(s)
ADP Ribose Transferases , Bacterial Toxins/chemistry , Histocompatibility Antigens/chemistry , Histocompatibility Antigens/metabolism , Membrane Glycoproteins , Poly(ADP-ribose) Polymerases/chemistry , Poly(ADP-ribose) Polymerases/metabolism , Protein Structure, Secondary , T-Lymphocytes/enzymology , Adenosine Diphosphate Ribose/metabolism , Amino Acid Sequence , Animals , Antigens, Differentiation, T-Lymphocyte , Arginine , Base Sequence , Cell Membrane/enzymology , Chickens , Chromatography, Affinity , Cloning, Molecular , Conserved Sequence , DNA Primers , Histocompatibility Antigens/biosynthesis , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred Strains , Molecular Sequence Data , NAD/metabolism , Poly(ADP-ribose) Polymerases/biosynthesis , Polymerase Chain Reaction , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid , Sequence Tagged Sites , Spleen/enzymology , TransfectionABSTRACT
CD40 is an integral membrane protein found on the surface of B lymphocytes, dendritic cells, follicular dendritic cells, hematopoietic progenitor cells, epithelial cells, and carcinomas. It is a 45-50 kDa glycoprotein of 277 aa, which is a member of the tumor necrosis factor receptor superfamily. The CD40 gene maps to human chromosome 20q11-2-q13-2. CD40 binds to a ligand (CD40-L) which is an approximately 35 kDa glycoprotein of 261 aa, a member of the tumor necrosis factor superfamily. The CD40-L gene maps to human chromosome Xq24. This CD40-L is expressed on activated T cells, mostly CD4+ but also some CD8+ as well as basophils/mast cells. The CD40-L is defective in the X-linked hyper-IgM syndrome. Cross-linking of CD40 with immobilized anti-CD40 or cells expressing CD40-L induces B cells to proliferate strongly, and addition of IL-4 or IL-13 allows the generation of factor-dependent long-term normal human B cell lines and the secretion of IgE following isotype switching. Addition of IL-10 results in very high immunoglobulin production with limited cell proliferation. IL-10 induces naive B cells to produce IgG3, IgG1, and IgA1, and further addition of TGF beta permits the secretion of IgA2. Several evidences suggest that CD40-dependent activation of B cells is important for the generation of memory B cells within the germinal centers: (i) CD40 activated germinal center B cells cultured in the presence of IL-4 acquire a memory B cell phenotype, (ii) CD40 activated B cells can undergo isotype switching, (iii) the deficit of CD40-L results in the hyper-IgM syndrome characterized by lack of germinal centers in secondary lymphoid organ follicles and lack of IgG, IgA, and IgE, and (iv) CD40-L positive T cells are present in secondary follicles. Thymic epithelial cells, activated monocytes, and dendritic cells express CD40 antigen which may be involved in an enhanced cytokine production by these cells, allowing an amplification of T cell proliferation. Finally, as other members of the tumor necrosis factor receptor family have been shown to bind several ligands, it is possible that CD40 may bind other ligands that may trigger CD40 on different cell types such as hematopoietic cells or epithelial cells.