Biomedical subjects

S Miscia

Publications and source records attributed to S Miscia.

At least 37 records · Page 2Linked to original sources

PubMed1995

Interferon beta mediated intracellular signalling traffic in human lymphocytes.

The early molecular mechanisms activated by the treatment of human lymphocytes with human interferon beta have been studied. These identify an early increase with respect to control, in diacylglycerol (DG) levels as response to interferon treatment. Such a DG production was derived from the rapid and sequential activation of phosphoinositide specific phospholipase C and phospholipase D pathway. This suggests that a synergistic involvement of phosphatidylinositol-bis-phosphate (PIP2) hydrolysis and phosphatidylcholine (PC) breakdown provide early molecular events upon the interaction between interferon beta and its cell surface receptors. This finally leads to the slowing down of cell growth.

Diglycerides↗

PubMed1995

Rapid and transient phosphorylation of nuclear matrix proteins upon interferon-alpha treatment in Daudi lymphoma cells.

Evidence for a rapid and transient hyperphosphorylation of a 45 kD protein in isolated nuclei from interferon-alpha-treated Daudi lymphoma cells is presented. Extraction of nuclear matrices from these nuclei has provided further evidence for the association of such a protein in the nuclear matrix structure. Because phosphorylation assays performed directly on nuclear matrices from interferon-treated cells have revealed rapid and transient increase of gamma 32P-ATP incorporation into this 45 kD band, an early involvement of the nuclear matrix in the response of the nucleus to the interferon antiproliferative message is suggested.

Antigens, Nuclear↗

PubMed1995

Phosphoinositide signalling enzymes in human T lymphocytes: modulation of phosphoinositidase C isoform gamma 1 upon interferon treatment.

In human T lymphocytes immunoblotting analysis of phosphoinositidase C (PIC) isoforms has shown that gamma 1 is the most represented isoform both at the cytoplasmic and nuclear level, and that interferon beta produces, within 90 min of treatment, an increase of its expression. These results, also supported by immunoelectronmicroscopic investigation, strongly suggest the involvement of PIC gamma 1 in the cascade of molecular events generated by the interaction between interferon and its cell surface receptors.

Cells, Cultured↗

PubMed1994

Interferon mediated phosphatidylinositol uptake and processing in nuclei isolated from Burkitt lymphoma cells.

The kinetic analysis of exogenous [3H]phosphatidylinositol (PI) uptake and processing by nuclei isolated from Daudi lymphoma cells upon interferon alpha treatment has been performed. Results have disclosed that, with respect to controls, interferon induces an evident stimulation of label incorporation into nuclei. The incorporated [3H] PI has been found for phosphorylation and hydrolytic cleavage, indicating that the intranuclear transduction system activated by interferon at plasma membrane level, might involve the PI cycle as a possible route of intracellular signalling.

Adenosine Triphosphate↗

PubMed1994

Evidence for an early and transient involvement of nuclear inositol lipids in subcellular signalling events related to DNA repair processes.

The involvement of nuclear inositol lipids in the processes related to DNA repair upon ionizing radiation has been investigated in Murine Erythroleukaemia cells. Early changes in the in vitro phosphatidylinositol-bisphosphate phosphorylation in isolated nuclei were found to precede transiently the marked increase in DNA synthesis occurring after irradiation. Such an increase detected by anti-BrdU monoclonal antibodies has been found to be related mainly to DNA polymerase beta activity as revealed by the kinetic analysis of in vitro DNA synthesis. The results here presented allow us to speculate on a possible involvement of nuclear inositol lipids in the cascade of the early events leading to the regulation of DNA repair in the nucleus.

Animals↗

PubMed1994

Nuclear phosphoinositide signalling enzyme in human B lymphoid cells.

The modulation of phosphoinositidase C (PIC) beta activity upon interferon treatment in Burkitt lymphoma cells (Daudi) and its localization and expression have been analyzed by Western blotting, immunocytochemical and immunoelectronmicroscopy analysis. Results have disclosed an early increase of phosphatidyl-inositol-bisphosphate (PIP2) hydrolysis at nuclear level upon interferon (IFN) treatment paralleled by the evidence of an increase of PIC beta 1 expression. PIC beta 1 expression has been detected in the nuclear compartment also in a clone of Daudi cells selected for the resistance to the antiproliferative action of interferon alpha but no modulation of the enzyme has been detected upon interferon treatment. Since no changes in terms of PIP2 hydrolysis have been found at nuclear level in this selected line, we suggest that the antiproliferative action of interferon on Burkitt lymphoma cells is mediated by a possible recruitment of nuclear PIC beta 1 expression.

B-Lymphocytes↗

PubMed1993

Interferon rapidly induces modifications of chromatin sensitivity to DNase I in Daudi lymphoma cells.

The DNase I sensitivity of total chromatin has been analyzed in nuclei isolated from control and interferon-treated Daudi cells. The electrophoretic analysis of DNA has evidenced a different pattern of DNA fragment size produced by DNase I in nuclei isolated from control cells compared to interferon-treated samples. This feature is supported by a different recovery of acid soluble chromatin and is accompanied by modifications of in vitro RNA synthesis along with initiation and elongation of RNA chains. No changes have been evidenced in nuclei isolated from Daudi-resistant cells under the same experimental conditions. These data might be interpreted as a transient modulation, induced by interferon, of chromatin structure in terms of chromatin condensation which, in turn, activates the RNA synthesis after the transduction into the nucleus of the interferon-generated signals.

Burkitt Lymphoma↗

PubMed1993

Inositol lipid-mediated intranuclear signalling: a comparative analysis of in vivo labelling in interferon alpha-sensitive and -resistant Daudi lymphoma cells.

Changes in inositol lipid and diacylglycerol metabolism have been analysed in Daudi lymphoma cells treated up to 24 h with human DNA recombinant interferon alpha. Results showing a different response of nuclear phosphoinositides and diacylglycerol, compared to whole cells, suggest that the intranuclear signalling system activated by interferon in Daudi cells involves nuclear inositol lipid metabolism. A well-characterized clone of Daudi cells selected for resistance to the antiproliferative action of interferon provided controls for the specificity of results.

Adolescent↗

PubMed1993

Evidence for nuclear phosphoinositidase C activity in the antiproliferative signals produced by interferon in Burkitt lymphoma cells.

The influence of interferon alpha on nuclear phosphoinositidase C (PIC) in Daudi cells has been analysed. Results showed an early increase of PIC activity detectable within 90 min of interferon treatment concomitant with an increase of diacylglcerol (DAG) levels. Since the interferon-induced DAG production is not modified by the addition of propranolol, a compound known to inhibit production of DAG from phosphatidylcholine hydrolysis, it is suggested that the interferon antiproliferative signal is transduced into the nucleus via the inositol lipid pathway. A parallel analysis performed on intact cells showed a rapid inhibition of PIC activity accompanied by an increase of DAG level thus suggesting that interferon-generated signals at plasma-membrane level use pathways different from that of inositol lipids. A selected clone of Daudi cells resistant to interferon action provided a control for specificity of results.

Burkitt Lymphoma↗

PubMed1993

Nucleolar morphological rearrangement related to transcriptional and replicative state in Burkitt lymphoma cells.

The specific silver staining of nucleolar region organizers was applied to Daudi lymphoma control and interferon alpha-treated cells. Isolated nuclei from control and treated samples were used for the kinetic analysis of in vitro RNA and DNA synthesis. Results have shown that interferon treatment induces a reduction of the transcriptional and replicative activities within 90 min. Concomitant to these results is the modification of the organization of nucleoli. Intensity and distribution of silver grains are, in fact, different in treated cells nucleoli as compared to those of controls. Thus, the number and the arrangement of granules could be related to the functional state of the cells suggesting that the transient cascade of interferon-generated signals involves also modulation of nucleolar structure and function in accordance with the hypothesis of a relationship of cell proliferation rate to silver-stained nucleolar protein quantity.

Amanitins↗

PubMed1993

Relationship between nuclear ribonucleoprotein arrangement and cell proliferation in Burkitt lymphoma cells.

The presence of body-like structures in nuclei from interferon alpha-treated Daudi cells has been shown on the ultrastructural level, by the use of different staining methods. The degree of their rearrangement in the nucleoplasm seems to be dependent on the time of interferon treatment. Since this morphological evidence has been found to be preceded by a slowing down of RNA transcriptional machinery early upon the interferon administration, it is speculated that interferon generated signals might lead to RNP granule accumulation in the nucleus and a consequent arrangement into defined structures.

Burkitt Lymphoma↗

PubMed1992

Interferon-mediated intracellular signalling. Modulation of different phospholipase activities in Burkitt lymphoma cells.

The effect of interferon-alpha on Daudi lymphoma cells either sensitive or resistant to the action of this cytokine has been analysed in terms of phospholipase C (PLC) and D (PLD) activities. Results have shown a combined modulation of PIP2-specific phospholipase C and phospholipase D. In particular, a decreased activity of PIP2-specific PLC has been found, concomitant to a PLD-mediated phosphatidylcholine hydrolysis, suggesting that the intracellular signalling activated by interferon in Daudi cells involves a phospholipase D/phosphohydrolase pathway.

Burkitt Lymphoma↗

PubMed1992

Age-related events in active T subpopulation. Changes in polyphosphoinositide metabolism during mitogenic activation.

The active E rosette test allows the characterisation of a lymphocyte subset with high affinity receptors for sheep red blood cells. In this study, we compared active T lymphocytes of healthy subjects over 65 and under 30 years of age after mitogenic stimulation. Active E rosettes increased in both age groups after 48 h of phytohemoagglutinin (PHA) stimulation, mainly in young subjects. In addition, analysing the in vitro phosphorylation of inositol lipids, changes occurred in the incorporation of radioactivity in both phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bis phosphate (PIP2) in the early steps of the mitotic response in the elderly subjects as compared to young ones, hinting that modifications of this signal transduction system are related to mitogenic stimulation in this peculiar T subpopulation.

Adult↗

PubMed1992

Interferon affects cell growth progression by modulating DNA polymerases activity.

A multiparametric analysis of the effects of human recombinant interferon alpha type A on Daudi cells involving flow cytometry and in vitro analysis of alpha and beta DNA polymerase activities has been performed. Results have disclosed (within 60 min of interferon treatment) a decrease of alpha polymerase driven DNA synthesis persisting to at least 24 h, while beta polymerase was poorly affected. Moreover, after 24 h of interferon treatment, a reduction of BrdUrd incorporation per cell, assessed by flow cytometry, was observed suggesting that DNA synthesis in S phase cells is almost completely abolished. The analysis of the effect of interferon on the distribution of cell cycle phases indicated that the G1/S transition is not inhibited by the treatment. These results support the hypothesis that interferon generates a transient initiating signal which quickly reaches the nucleus and produces a rapid inhibition of alpha polymerase activity, leading finally to the slowing of cell cycle progression.

Cell Cycle↗

PubMed1991

Nuclear metabolic changes induced by tumor necrosis factor in Daudi lymphoma cells; a multiparametric analysis.

The effects of r-TNF alpha on cell cycle progression and DNA polymerase activity in Daudi lymphoma cells have been analyzed. Cytofluorimetric analysis of the cell cycle after 6 to 24 hr of treatment revealed both a decrease of BrdU incorporation per cell and a light inhibition of S phase as assessed by the analysis of the percentual distribution of cell cycle compartments. The reduction of BrdU incorporation can be related to the early decrease in the rate of DNA synthesis that follows r-TNF alpha treatment. These results suggest that one of the early events induced by r-TNF alpha at nuclear level is the slowering of DNA synthesis leading to a reduced cell cycle progression.

Bromodeoxyuridine↗

PubMed1991

Interferon transiently modulates intranuclear signalling system in erythroleukemia Friend cells.

The effect of human recombinant DNA interferon alpha type A on nuclear inositol lipids, diacylglycerol (DAG) and DNA metabolism has been investigated in Friend erythroleukemia cells. A transient enhancement of phosphatidylinositol (4,5) - bisphosphate (PIP2) phosphorylation together with an increase of diacylglycerol mass were observed in nuclei isolated from cells treated with interferon alpha for 90 min. At the same time, a marked reduction of DNA polymerase alpha activity was observed, suggesting a possible involvement of nuclear inositol fraction in the response of the cell nucleus to interferon treatment.

Animals↗

PubMed1990

Transient shift of diacylglycerol and inositol lipids induced by interferon in Daudi cells. Evidence for a different pattern between nuclei and intact cells.

The effect of human recombinant DNA interferon-alpha type A on inositol lipid and diacylglycerol metabolism was investigated in Daudi lymphoma whole cells and isolated nuclei. In isolated nuclei after 90 min of interferon treatment an enhanced rate of PIP2 phosphorylation and an increase of DAG mass were observed. In whole cells, after 1 min of interferon treatment, there was a rapid and transient shift of DAG mass apparently not related to inositol lipid modifications, thus indicating the presence in nuclear and cytoplasmic compartments of inositol lipid fractions with different metabolic features in response to interferon-alpha.

Adenosine Triphosphate↗

PubMed1990

Early modifications of nucleic acid metabolism and nuclear lipid biosynthesis associated with antiproliferative activity of interferon-alpha on Daudi lymphoma cells.

The effect of human recombinant DNA interferon-alpha type A (rIFN alpha A) on nuclear lipid biosynthesis and on in vitro nucleic acid synthesis was investigated in Daudi lymphoma cells sensitive (Daudi Is) or resistant (Daudi Ir) to the antiproliferative activity of this glycoprotein. In the Daudi Is studied at 90 min and up to 8 h, relative proportions of 3H-labeled nuclear lipids were reproducibly altered as compared to controls: phosphatidylcholine increased while phosphatidylserine and total neutral lipids decreased. These changes were not detected in parallel studies of the whole cell extracts. No significant changes in the profiles of nuclear lipids were observed in Daudi Ir. Decreased rates of alpha DNA polymerase and of RNA transcription were evident within 90 min in the Daudi Is nuclei but not in untreated controls or nuclei from rIFN alpha A-treated Daudi Ir cells, thus suggesting a possible relationship of the rapid alterations of nuclear lipid biosynthesis in Daudi Is cells to the rIFN alpha A antiproliferative activity.

Burkitt Lymphoma↗