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P Jansa

Publications and source records attributed to P Jansa.

At least 19 recordsLinked to original sources
PubMed1999

Mechanism of transcription termination: PTRF interacts with the largest subunit of RNA polymerase I and dissociates paused transcription complexes from yeast and mouse.

Transcription termination by RNA polymerase I (Pol I) is a stepwise process. First the elongating RNA polymerase is forced to pause by DNA-bound transcription termination factor (TTF-I). Then the ternary transcription complex is dissociated by PTRF, a novel factor that promotes release of both nascent transcripts and Pol I from the template. In this study we have investigated the ability of PTRF to liberate transcripts from ternary transcription complexes isolated from yeast and mouse. Using immobilized, tailed templates that contain terminator sequences from Saccharomyces cerevisiae and mouse, respectively, we demonstrate that PTRF promotes release of terminated transcripts, irrespective of whether mouse Pol I has interacted with the murine termination factor TTF-I or its yeast homolog Reb1p. In contrast, mouse Pol I paused by the lac repressor remains bound to the template both in the presence and absence of PTRF. We demonstrate that PTRF interacts with the largest subunit of murine Pol I, with TTF-I and Reb1p, but not the lac repressor. The results imply that Pol I transcription termination in yeast and mouse is mediated by conserved interactions between Pol I, Reb1p/TTF-I and PTRF.

Animals↗
PubMed1998

Cloning and functional characterization of PTRF, a novel protein which induces dissociation of paused ternary transcription complexes.

Termination of transcription by RNA polymerase I (Pol I) is a two-step process which involves pausing of elongating transcription complexes and release of both pre-rRNA and Pol I from the template. In mouse, pausing of elongation complexes is mediated by the transcription termination factor TTF-I bound to the 'Sal box' terminator downstream of the rDNA transcription unit. Dissociation of paused ternary complexes requires a cellular factor, termed PTRF for Pol I and transcript release factor. Here we describe the molecular cloning of a cDNA corresponding to murine PTRF. Recombinant PTRF is capable of dissociating ternary Pol I transcription complexes in vitro as revealed by release of both Pol I and nascent transcripts from the template. Consistent with its function in transcription termination, PTRF interacts with both TTF-I and Pol I. Moreover, we demonstrate specific binding of PTRF to transcripts containing the 3' end of pre-rRNA. Substitution of 3'-terminal uridylates by guanine residues abolishes PTRF binding and impairs release activity. The results reveal a network of protein-protein and protein-nucleic acid interactions that governs termination of Pol I transcription.

Amino Acid Sequence↗
PubMed1996

A novel type of retinoic acid response element in the second intron of the mouse H2Kb gene is activated by the RAR/RXR heterodimer.

We have identified and characterized a novel retinoic acid (RA) response element (Hi-RARE) in the second intron of the mouse major histocompatibility H2Kb gene. The Hi-RARE sequence is conserved in all mouse classical and Q class 1 genes, in MHC class 1 genes of the rat, Rhesus macaque, cat and in the vast majority of human classical and non-classical class 1 genes. The Hi-RARE sequence lies within a regulatory element responsible for constitutive expression of a 5' enhancerless H2Kb gene in the Ltk-fibroblasts. Hi-RARE consists of two inverted palindromic RARE consensus sites (5'-PuGGTCA-3') separated by an 8 nt spacer. Mutational analysis revealed that both inverted palindromic hexanucleotide motifs are indispensable functional sites for the 9-cis RA response. The Hi-RARE sequence confers 9-cis RA inducibility to a heterologous promoter. The inducibility is further augmented in embryonal carcinoma cells by the expression of recombinant retinoic acid receptors (PARs) and the retinoid X receptors (RXRs). In vitro, the recombinant RAR/RXR heterodimer creates DNA-protein complex with the Hi-RARE sequence. Treatment of P19 embryonal carcinoma cells with 9C-RA induces the Hi-RARE binding activity of nuclear proteins that proved to be RAR (or RAR-Like)/RXR heterodimer. Thus the Hi-RARE represents a new type of RA response element with a role in the modulation of the expression of MHC class 1 family genes.

Animals↗
PubMed1996

Identification of an intragenic interferon-stimulated response element sequence of the mouse class I major histocompatibility complex H-2Kb gene.

A 5'-enhancer-lacking construct of the mouse MHC class I H-2Kb gene is stimulated by interferons in a similar manner as a 5'-enhancer-containing H-2Kb gene. This ability is markedly reduced upon introducing a second deletion removing the first and second intron of the H-2Kb gene. Computational analysis of the deleted stretch reveals the presence of the interferon-stimulated response element (ISRE) in the middle of the second intron. The identified sequence exhibits typical ISRE characteristics in gel retardation experiments. A fragment containing the 5'-enhancer interferon responsive sequence competes effectively in the binding reactions. These results strongly suggest that the second intron of the H-2Kb gene participates in interferon stimulation via the identified ISRE sequence.

Animals↗
PubMed1993

Proliferation of reticuloendothelial system (RES) in rats with altered vision or smell (to the hypothetic neural regulation of the RES).

A long-term administration of an azo-dye, trypan blue, induced a reactive proliferation of RES in rats. Reaction of the RES was followed in rats whose optical analyzer was eliminated by enucleation of bulbs after the birth, in rats whose smell analyzer was altered by a repeated long-term exposition to ammoniac and in normal rats. Blind rats showed a striking proliferation of histiocytes of the RES in the liver, while the reaction was weak in the spleen and lymph nodes. In contrary to that, rats with altered smell and also the normal rats exhibited standard reactive changes in the spleen and lymph nodes and distinctly weaker reaction in the liver. The obtained results support an idea that vegetative neural mechanisms play a role in control and coordination of RES reactions.

Ammonia↗
PubMed1992

A novel downstream regulatory element of the mouse H-2Kb class I major histocompatibility gene.

The H-2Kb gene equipped with a minimal promoter (5' deletion up to -61) was fully expressed in transfected fibroblasts, but inactive in transfected embryonal carcinoma cells. A strong transcriptional regulatory element (H2DRE) was identified when a fragment spanning the second exon and second intron was used to activate transient expression of the reporter chloramphenicol acetyltransferase (CAT) gene in mouse Ltk- or NIH3T3 fibroblasts. Its activity was twice that of a construct where the CAT gene was driven by the H-2Kb 5' enhancer region (H2TF1/KBF1 site) and comparable to that of pRSVCAT construct carrying the strong Rous sarcoma virus LTR enhancer. In accord with regulated transcriptional activity of the intact H-2Kb gene, the H2DRE did not activate the CAT expression in P19 mouse embryonal carcinoma cells. The H2DRE did not function as a typical enhancer since its activity was strongly position dependent. Consistent with its anticipated role in transcription regulation, H2DRE displayed more than five target sites for specifically interacting nuclear factors, two of them being present in H-2 positive fibroblasts, but not in H-2 negative teratocarcinoma cells. None of them was cross-competed by sequences of the 5' enhancer. The results of deletion experiments show that H2DRE is the only regulatory region that can activate transcription from the 5' enhancerless H-2Kb gene in mouse L fibroblasts.

Animals↗
PubMed1992

[Monitoring immunosuppression after kidney transplantation. I. Study of cellular reactions to antigenic stimulus in a skin abrasion].

In 20 patients the authors performed in the course of 6-8 weeks following renal transplantation a total of 74 examinations of the cellular reaction to an antigenic stimulus. In 68 instances (91.9%) agreement with the clinical picture was recorded, while in 6 patients (8.1%) the interpretation of the cytological impression did not correspond to the clinical course. In four instances activation of lymphocytes was found, i.e. possible risk of rejection which however was not confirmed. In two instances however incipient rejection was not detected.

Adult↗
PubMed1992

[Monitoring immunosuppression after kidney transplantation. II. Evaluation of simultaneous monitoring of CD4+ lymphocytes and the cytological reaction to standard antigenic stimulation].

Monitoring of patients after renal transplantations by the concurrent follow up of absolute values of CD4+ lymphocytes and the cytological reaction to an antigenic stimulation in a skin abrasion reflects the actual immune state of patients and is an asset in the comprehensive diagnosis of rejection activity against the transplant in the early period (6-8 weeks) after transplantation. It can contribute also to the signalling of developing rejection activity against the graft, before the onset of the fully developed clinical picture of rejection, when it is possible by early anti-rejection therapy to prevent the functional impairment of the renal graft.

Adult↗
PubMed1992

[Expression of the blood group antigens A and B in carcinoma of the urinary bladder].

In 21 patients with transitional cell carcinoma of the urinary bladder expression of A and B blood group antigens was studied by means of monoclonal antibodies on using indirect immunoperoxide reaction. Expression of the investigated antigens was found to be dependent on the degree of histological differentiation of the tumor tissue. In well-defined carcinomas mostly pronounced expression of A and B blood group antigens was observed. Middle and low-differentiated carcinomas were characterized by reduction or even total deletion of expression. The expected favorable prognosis in transitional cell carcinomas expressing A and B blood group antigens failed to be confirmed. The expression of incompatible A-like antigens in 0 and B blood group patients with carcinoma is discussed. (Tab. 3, Fig. 3, Ref. 22.).

ABO Blood-Group System↗
PubMed1991

Regional lymph nodes in cancer III. B-lymphocyte region.

The available evidence on the reaction of B-cell zone, the role of B-cell response in interactions with T-cells, MPS cells, tumor antigens and antigen-antibody complexes is presented. The authors comment the interpretation of B-cell response in prognosis of cancer patients.

Animals↗
PubMed1991

Regional lymph nodes in cancer. IV. T-lymphocyte region.

The data on the role of T-cell reaction in interactions with B-cell response and MPS reaction are summarized. The importance of paracortical activity (T-zone) in experimental and human tumors is discussed with regard to prognostic interpretation of T-cell response.

Animals↗
PubMed1991

Histochemistry of mucosubstances in the diffuse and intestinal types of gastric cancer.

Histochemical properties of the mucus were studied in 48 diffuse types and 46 intestinal types of gastric carcinoma. Diffuse type was characterized by the prevalence of intracellular secretion of mucopolysaccharides with a significant involvement of sulfated ones. In the intestinal type, extracellular secretion predominated with the occurrence of pure acid mucopolysaccharides and a smaller portion of sulfated ones. The secretion of pure neutral mucopolysaccharides was minimal in both types of gastric cancer. In the intestinal type carcinomas, incomplete intestinal type IIb metaplasia was frequently found in marginal areas of the tumor.

Adenocarcinoma↗
PubMed1991

Blood group H antigen in transitional carcinoma of the urinary bladder.

A total of 21 transitional carcinomas of the urinary bladder were examined by the method of indirect immunoperoxidase reaction using anti-H monoclonal antibody. Expression of blood group H antigen was detected in ten cases but no association with the grade of differentiation of the tumor tissue was established. The prognosis of carcinomas expressing blood group H antigen is not more favorable than that of carcinomas with absent expression.

ABO Blood-Group System↗
PubMed1991

[Expression of A,B and H blood group antigens in urothelial carcinoma of the urinary bladder].

Expression of blood group antigens A, B, and H was studied in transitional carcinoma of the urinary bladder. Positive result was obtained in 16 cases of a group of 21 tumours by indirect immunoperoxidase reaction with monoclonal antibodies. A relation of quantitative expression to histological grading of tumour differentiation was noticed. Well differentiated transitional carcinomas mostly had more conspicuous expression of A, B, and H antigens. However, expected more favourable prognosis in cases of transitional carcinoma with expression of A, B, and H blood group antigens failed to be proved.

ABO Blood-Group System↗
PubMed1990

Effect of He-Ne laser on early phase of reparation.

The mechanism of the effect of He-Ne laser light was studied in the group of 22 healthy volunteers using the method of skin window. The imprint preparations of cell reaction from a reparative inflammation were examined 12, 24, and 48 hours after irradiation. It was concluded that single higher doses of radiation (50 J/cm2) accelerate the onset of macrophages in the inflammatory field and thus facilitate a more rapid and successful recovery of skin lesions.

Adolescent↗
PubMed1990

Regional lymph nodes in cancer. II. Macrophages.

The survey is given of the actual knowledge of mononuclear phagocyte system which is involved in reactive changes of regional lymph nodes in experimental and human tumors. The practical aspects of their role in the development of tumors are discussed.

Animals↗
PubMed1990

Blood-group related antigens A and B in gastric cancer.

Using monoclonal antibodies the expression of blood group antigens A and B was studied by the method of indirect immunoperoxidase reaction in a series of 48 gastric carcinomas classified by Laurén's criteria into diffuse and intestinal types. Expression in intestinal and diffuse types of carcinoma differed significantly in patients of blood group A and AB. Intestinal type was characterized by a marked heterogeneity of expression of blood group antigens, while diffuse type displayed a homogeneous expression. The observed differences testify the validity of Laurén's classification. A more frequent staining of supranuclear regions of the cytoplasm of tumor cells in intestinal type carcinoma was recorded with the monoclonal antibody HE 10 (reacting with antigenic determinants A and H of type 3 and 4). A possible prognostic significance of this finding is discussed.

ABO Blood-Group System↗