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Biomedical subjects

M Kaluzova

Publications and source records attributed to M Kaluzova.

10 recordsLinked to original sources
PubMed2000

Acute effects of interferon on estrogen receptor function do not involve the extracellular signal-regulated kinases p42mapk and p44mapk.

Exposure to type I interferons (IFN) increased estrogen receptor (ER) ligand binding and induced protein kinase C (PKC) translocation within 30 min but had no effect on net incorporation of [32P] into ER in Madin Darby bovine kidney (MDBK) cells. Ligand binding was also increased within 30 min by phorbol ester and the protein phosphatase inhibitor okadaic acid. Mitogen-activated protein (MAP) kinase phosphorylation was initially inhibited between 2 and 30 min and subsequently activated between 30 and 60 min after treatment with IFN. The activatory response was blocked by the PKC inhibitor Ro 31-8220. Following transient transfection with an ERE-CAT reporter construct, IFN increased CAT expression after 6 h but decreased ER ligand binding, transcriptional activity and phosphorylation after 48 h, probably as a result of decreased ER concentrations. The results rule out rapid activation of ER ligand binding through phosphorylation at Ser118 by MAP kinase because (1) the increase in ligand binding preceded activation of MAP kinase, and (2) IFN had no short-term effect on [32P]incorporation or ER transcriptional activity. The rapid effect of IFN on ER ligand binding is postulated to reflect phosphorylation of the receptor at Tyr537 by p56lck, a member of the Src family of PKC-activated tyrosine kinases.

Animals↗
PubMed1999

Co-transfected SV40 origin of replication activates expression from SV40 promoterless constructs.

Co-transfection with expression plasmids is widely used to control DNA uptake efficiency in transient transfection experiments. However, a number of problems have been associated with their use. Here, we describe the activation of expression of constructs not containing the simian virus 40 (SV40) origin of replication (ori) by co-transfection in COS-7 cells with plasmids containing the SV40 ori. This effect has consequences for the use of such plasmids to control transfection efficiency.

Animals↗
PubMed1998

Up-regulation of p53 by antisense expression of HPV18 E6 oncogene does not influence the level of MN/CA IX tumor-associated protein in HeLa cervical carcinoma cells.

Oncogenic potential of human papillomaviruses is related to capacity of HPV-encoded oncoproteins to bind and inactivate tumor suppressor proteins. Interaction of p53 with HPV E6 results in aberrant regulation of various cellular genes. We evaluated the possible involvement of MN/CA9 gene, whose expression is closely associated with cervical carcinomas, in regulatory pathways driven by p53 and E6. We demonstrated that one of the two p53 consensus sequences present in MN/CA9 promoter participates in DNA-protein interaction but it does not bind p53. Tetracycline-inducible antisense expression of HPV18 E6 in human cervical carcinoma HeLa cells resulted in increased level of p53 but did not affect expression of MN/CA IX protein. Therefore we conclude that at least in HeLa cells there is no direct relationship between expression of MN/CA IX and expression of E6 or p53.

DNA, Complementary↗
PubMed1997

Sequencing analysis of prion genes from red deer and camel.

An abnormal isoform of the prion protein (PrP) appears to be the agent responsible for transmissible spongiform encephalopathies (TSE). The normal isoform of PrP is host-encoded and expressed in the central nervous system. The recent bovine spongiform encephalopathy (BSE) epidemic in the UK and the incidence of prion-related diseases in other animals could indicate that ruminants are highly susceptible to infection via ingestion of prion-contaminated food. Sequence analysis of PrP gene open reading frames from red deer and camel was carried out to investigate sequence variability of these genes among ruminants.

Amino Acid Sequence↗
PubMed1996

Heterogeneity in the third intracytoplasmic region of the oxytocin receptor-encoding gene.

The oxytocin receptor (OTR), a member of the seven-transmembrane domain guanine-nucleotide-binding protein (G protein) coupled receptor family plays a central role in lactation, ovarian cyclicity and reproductive behaviour. Recent cloning and sequencing unexpectedly revealed that the third intracytoplasmic region (3ICR) of the sheep receptor has 3 and 2 additional amino acids (aa) relative to the rat and human receptors, respectively. We have now confirmed, by sequencing polymerase chain reaction (PCR)-derived genomic fragments coding for the OTR 3ICR from a variety of ruminant and non-ruminant species, that additional aa are a general phenomenon in ruminants.

Amino Acid Sequence↗
PubMed1996

Structure of an ovine interferon receptor and its expression in endometrium.

A sheep type I interferon receptor (oIFNAR1) cDNA was isolated from a lambda-ZAP library using a reverse transcription (RT)-PCR product probe generated from oestrous endometrial RNA. The oIFNAR1 cDNA was 79, 66 and 95% homologous to human, murine and bovine IFNAR1 cDNAs respectively. The encoded receptor was a 560-amino acid transmembrane protein 80, 66 and 95% similar to human, murine and bovine IFNAR1 respectively. Northern blot analysis of endometrial mRNA revealed the presence of 6.5, 4.3 and 3.7 kb transcripts. Using semi-quantitative RT-PCR the oIFNAR1 mRNA was not found to be down-regulated after 72 h treatment with bovine recombinant IFN-alpha I in in vitro experiments with endometrial explants.

Amino Acid Sequence↗
PubMed1994

Change in phenotype of tick-borne encephalitis virus following passage in Ixodes ricinus ticks and associated amino acid substitution in the envelope protein.

Serial passage of an uncloned tick-borne encephalitis virus (strain 4387 isolated from the liver and lungs of a bank vole) in Ixodes ricinus ticks, was accompanied by gradual reduction in virulence of the virus, as indicated by transmission of virus by infected ticks feeding on laboratory mice. After the 7th serial passage in ticks (strain 4387/7), 95% of mice survived the bite of infected ticks. The surviving infected mice showed either no or only low viraemia although virus could be isolated from the brains of some mice 14 and 30 days after commencement of tick feeding, implying that the tick passaged virus might have established a persistent infection in the mice. Tests for haemagglutinating capacity were positive with TBE strain 4387 but strain 4387/7 exhibited no haemagglutinating activity over a wide pH range, suggesting that phenotypic changes, resulting from selection, had affected the site on the viral envelope protein that binds red blood cell receptors. Sequencing of the envelope protein gene of the virulent TBE strain 4387 showed 3 amino acid codon differences from western European TBE virus strain Neudorfl, which is also virulent for mice. The attenuated virus 4387/7, had an amino acid substitution that was different from 4387 and Neudorfl TBE virus (amino acid 84, E to K) and a second substitution different from 4387 but identical to Neudorfl virus (amino acid 319, I to T). Thus, the phenotypic change from virulence to attenuation was associated with a single amino acid codon change in the viral envelope gene of TBE virus. It is recognised, however, that amino acid substitutions in other parts of the viral genome have not been ruled out.

Amino Acid Sequence↗