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Biomedical subjects

S Pestka

Publications and source records attributed to S Pestka.

302 records · Page 17Linked to original sources
PubMedDate not supplied

Antisense RNA: effect of ribosome binding sites, target location, size, and concentration on the translation of specific mRNA molecules.

A series of plasmids were constructed to generate RNA complementary to the beta-galactosidase messenger RNA under control of the phage lambda PL promoter. These plasmids generate anti-lacZ mRNA bearing or lacking a synthetic ribosome binding site adjacent to the lambda PL promoter and/or the lacZ ribosome binding site in reverse orientation. Fragments of lacZ DNA from the 5' and/or the 3' region were used in these constructions. When these anti-mRNA molecules were produced in Escherichia coli 294, maximal inhibition of beta-galactosidase synthesis occurred when a functional ribosome binding site was present near the 5' end of the anti-mRNA and the anti-mRNA synthesized was complementary to the 5' region of the mRNA corresponding to the lacZ ribosome binding site and/or the 5'-coding sequence. Anti-mRNAs producing maximal inhibition of beta-galactosidase synthesis exhibited an anti-lacZ mRNA:normal lacZ mRNA ratio of 100:1 or higher. Those showing lower levels of inhibition exhibited much lower anti-lacZ mRNA:normal lacZ mRNA ratios. A functional ribosome binding site at the 5'-end was found to decrease the decay rate of the anti-lacZ mRNAs. In addition, the incorporation of a transcription terminator just downstream of the antisense segment provided for more efficient inhibition of lacZ mRNA translation due to synthesis of smaller and more abundant anti-lacZ mRNAs. The optimal constructions produced undetectable levels of beta-galactosidase synthesis.

Binding Sites↗
PubMedDate not supplied

A convenient assay for detection of soluble interferon receptors.

The most common problem that must be overcome in purification of plasma membrane receptors from a cell line or a tissue is the loss of activity after solubilization with a detergent. This paper describes a simple dot blot assay with 32P-labeled human interferon gamma (Hu-IFN-gamma) for the detection of a functionally active Hu-IFN-gamma receptor from soluble plasma membranes prepared from human placenta.

Female↗
PubMedDate not supplied

Regulation of the antigenic phenotype of human melanoma cells by recombinant interferons.

The ability of interferons to modulate the antigenic phenotype of tumor cells may involve alterations in the transcription, translation, membrane expression and shedding of Major Histocompatibility Complex (MHC) and Tumor Associated Antigens (TAAs). In the present study we have investigated possible mechanisms by which recombinant human interferons, IFN-alpha, -beta and -gamma, alter the antigenic profile of long- and short-term human melanoma cultures. IFN-alpha and -beta induced similar changes in the synthesis, expression and shedding of two TAAs, a HMW-MAA and a Cyt-MAA, in the established melanoma cell line Colo 38, whereas IFN-gamma exerted a differential effect on these melanoma associated antigens. Moreover, IFN-gamma was relatively more effective than IFN-alpha or -beta in upregulating the synthesis, expression and shedding of class I MHC antigens. At the same time a dramatic differential effect of the interferons was observed with class II MHC antigens. IFN-alpha or -beta induced a modest increase in the synthesis and expression of these antigens, whereas IFN-gamma was greater than 3-fold more active in inducing the synthesis and expression of DR/DP antigens and greater than 4- and greater than 10-fold more effective in increasing the synthesis and expression, respectively, of DQ antigens. Analysis of the levels of cytoplasmic mRNA for the DR-alpha and DQ-beta genes indicated no significant difference between IFN-alpha, beta or -gamma treated cells suggesting that IFN-gamma enhancement of the synthesis of DR and DQ antigens may occur at a posttranscriptional level. In the case of a newly established human melanoma cell line (MG-3) IFN-gamma enhanced the synthesis but not the expression of DR antigens and did not alter either the synthesis or expression of DQ antigens. Our studies indicate that the effects of interferons on the antigenic phenotype of melanoma cells will vary depending on the type of interferon employed, the antigen monitored and the target cell studied. In addition, it is also apparent that some of the biosynthetic steps involved in regulating the synthesis, expression and shedding of antigens may be coordinately regulated in some melanoma cells, whereas these processes may be under independent control in other melanoma populations.

Antigens, Neoplasm↗
PubMedDate not supplied

Construction of a modified murine interferon alpha with increased stability.

The mutant [Ser86] murine interferon alpha A was constructed by oligodeoxyribonucleotide-directed site-specific mutagenesis and expressed under the control of lambda phage PL promoter in Escherichia coli. The effect of the substitution of serine for the cysteine residue at position 86 in the murine interferon alpha A was studied. It was observed that the mutant Ser86 murine interferon alpha A which does not contain the free cysteine residue in the peptide was inactivated more slowly than its parent with a free cysteine residue at position 86. Heat-inactivated murine interferon alpha A cannot be reactivated, but the heat-inactivated Ser86 derivative can be reactivated significantly to about 27.5 per cent of the original activity in the presence of sodium dodecylsulfate. These results suggest that the free cysteine in the peptide is a factor contributing to the instability of the protein.

Bacteriophage lambda↗
PubMedDate not supplied

Effect of recombinant human fibroblast interferon and mezerein on growth, differentiation, immune interferon binding and tumor associated antigen expression in human melanoma cells.

The combination of recombinant human fibroblast interferon (INF-delta) and the antileukemic compound mezerein (MEZ) results in a synergistic suppression in the growth of human melanoma cells and a concomitant increase in melanin synthesis. In the present study we have further analyzed this synergistic interaction and have also evaluated the effect of IFN-delta and MEZ, alone and in combination, on recombinant human gamma interferon (IFN-gamma) binding and Class I HLA and melanoma associated antigen (MAA) expression in the HO-1 human melanoma cell line. Single cell clones isolated from the HO-1 cell line varied in their sensitivity to the antiproliferative effects of IFN-delta and MEZ. With all twelve clones, however, the combination of IFN-delta plus MEZ was more growth inhibitory than either agent used alone, even in HO-1 subclones displaying relative resistance to IFN-delta. By continuous growth in gradually increasing concentrations of IFN-delta, a variant population of HO-1 cells, HO-1 delta R-D, was generated which was more resistant to the antigrowth effects of IFN-delta than the original HO-1 parental cell line. In the IFN delta R-D cell line the combination of IFN-delta plus MEZ synergistically suppressed growth. Exposure of HO-1 cells to 2500 units/ml IFN-delta or 50 ng/ml MEZ for 96 hr resulted in no change or an increase in the binding of labelled IFN-gamma to surface receptors, whereas the combination of IFN-delta plus MEZ increased IFN-gamma binding 2-to-4-fold in HO-1 cells. This increase was the result of an increase in the number of receptors on treated cells coupled with a protection against a decrease in receptors observed for confluent untreated cells. Changes in IFN-gamma binding resulting from treatment with IFN-delta plus MEZ were not associated with alterations in the binding affinity of INF-gamma to its receptor. Changes were also observed in the expression of HLA Class I antigens and MAAs following treatment of HO-1 cells with IFN-delta, MEZ or IFN-delta plus MEZ. IFN-delta and MEZ increased the expression of HLA Class I antigens a 96 kd MAA defined by MoAb CL203, a 100 kd MAA defined by MoAb 376.96 and a 115 kd MAA defined by MoAb 345.134 but decreased the expression of a high molecular weight-melanoma associated antigen (HMW-MAA) defined by MoAb 325.28S.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, Neoplasm↗
PubMedDate not supplied

Expression of human interferon alpha H, an interferon with two potential asparagine-linked glycosylation sites.

Of the large number of human alpha interferon genes identified, only one, Hu-IFN-alpha H, contains potential asparagine-linked glycosylation sites. With the use of a new vector that permits convenient expression, site-specific mutation, and DNA sequencing, Hu-IFN-alpha H was expressed in Escherichia coli. The bacterial product which is not glycosylated is fully active demonstrating that the carbohydrate on this species is not required for antiviral activity.

Asparagine↗
PubMedDate not supplied

Construction of phosphorylatable monoclonal antibody CC49 with a casein kinase II recognition site.

A phosphorylation site for casein kinase II was introduced into chimeric monoclonal antibody CC49 (MAb-chCC49) by site-specific mutation of the coding sequence. The phosphorylation site for the casein kinase II was positioned at the carboxyl terminus of the heavy chain constant region of the MAb-chCC49. The resultant modified MAb-chCC49CKII was expressed in NS0 cells and purified. The MAb-chCC49CKII protein was phosphorylated by casein kinase II with [gamma-32P]ATP to high radiospecific activity. The 32P-labeled MAb-chCC49CKII binds to cells expressing TAG-72 antigens. The introduction of the phosphorylation sites for casein kinase II into monoclonal antibodies (MAb) provides a new reagent for the diagnosis and treatment of cancers. This demonstrates that the casein kinase II recognition site can also be used to introduce phosphorylation sites into proteins.

Amino Acid Sequence↗