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Biomedical subjects

H R Herschman

Publications and source records attributed to H R Herschman.

At least 19 recordsLinked to original sources
PubMed1992

Dexamethasone inhibits mitogen induction of the TIS10 prostaglandin synthase/cyclooxygenase gene.

Glucocorticoids block the induced secretion of prostaglandins in a variety of biological contexts. We have identified a primary response gene, TIS10, which encodes a mitogen-inducible prostaglandin synthase/cyclooxygenase in Swiss 3T3 cells. TIS10 is distinct from prostaglandin synthase/cyclooxygenase. (EC 1.14.99.1), previously cloned from mouse, man, and sheep. Dexamethasone blocks prostaglandin E2 synthesis by 3T3 cells in response to tetradecanoylphorbol acetate. Dexamethasone also blocks both phorbol ester- and forskolin-induced TIS10 mRNA accumulation. In contrast, phorbol esters, forskolin, and dexamethasone have little or no effect on the levels of prostaglandin synthase/cyclooxygenase mRNA in 3T3 cells. Moreover, dexamethasone does not inhibit induction of TIS8/egr-1, another primary response gene. Inhibition of the synthesis of TIS10 prostaglandin synthase/cyclooxygenase may be a principal mechanism by which glucocorticoids block prostaglandin synthesis and secretion.

3T3 Cells↗
PubMed1992

Structure of the mitogen-inducible TIS10 gene and demonstration that the TIS10-encoded protein is a functional prostaglandin G/H synthase.

The TIS10 cDNA was cloned as a primary response gene transcript whose mRNA rapidly accumulates in 3T3 cells treated with serum, polypeptide growth factors, or phorbol esters. The sequence of the TIS10 cDNA suggested that the gene encodes a protein with strong similarities to prostaglandin G/H synthase/cyclooxygenase (EC 1.14.99.1). Transient transfection into COS-1 cells of an expression vector driving the TIS10 cDNA leads to production and secretion of prostaglandin E2. Microsomes prepared from COS-1 cells transfected with this construct demonstrate both hydroperoxidase and cyclooxygenase activities similar to that demonstrated by cells transfected with a vector encoding the ovine prostaglandin G/H synthase. These data demonstrate that the TIS10 gene encodes a functional prostaglandin synthase/cyclooxygenase distinct from the prostaglandin synthase/cyclooxygenase whose cDNAs and/or genes have previously been cloned from sheep, mouse, and man. The structure of the TIS10 gene, determined by a combination of sequencing of genomic clones and polymerase chain reactions from genomic clones, demonstrates remarkable exon-intron conservation with the human prostaglandin synthase/cyclooxygenase gene. A 1-kilobase sequence located immediately proximal to the start site of transcription of the TIS10 gene can confer phorbol ester and serum inducibility to a luciferase reporter gene following transient transfection into NIH 3T3 cells, suggesting that this region of the gene is responsible for transcriptional regulation of the TIS10 gene by mitogens in fibroblasts.

3T3 Cells↗
PubMed1991

Structure and expression of TIS21, a primary response gene induced by growth factors and tumor promoters.

The TIS21 gene is a primary response gene that is induced rapidly and transiently in 3T3 cells by the tumor promoter and mitogen tetradecanoyl phorbol acetate. The predicted open reading frame of the TIS21 cDNA encodes a protein of 158 amino acids with no obvious similarity to any known protein. Antiserum prepared to TIS21 recombinant protein produced in Escherichia coli precipitates a 17-kDa protein from Swiss 3T3 cells. The 2040-nucleotide 3'-untranslated region of the cDNA includes an unusual T18 sequence. The TIS21 gene has a single 1.4-kilobase intron which interrupts the open reading frame and is otherwise identical to the cDNA sequence. The 5'-flanking sequence of the TIS21 gene contains TATA and CAAT box-type sequences, three potential Sp1 sites, two putative cyclic AMP response elements, two potential AP1 binding elements, and an AP2 element. A possible Z-DNA structure of 29 AC repeats is present 660 nucleotides from the start of transcription. Expression from a luciferase reporter construct containing a 460-nucleotide fragment of the TIS21 promoter is induced by tetradecanoyl phorbol acetate, forskolin, epidermal growth factor, and serum, despite the absence of a consensus serum response element.

Amino Acid Sequence↗
PubMed1991

TIS10, a phorbol ester tumor promoter-inducible mRNA from Swiss 3T3 cells, encodes a novel prostaglandin synthase/cyclooxygenase homologue.

TIS10 is a primary response gene whose cDNA was cloned as a result of its rapid, superinducible expression in Swiss 3T3 cells in response to 12-O-Tetradecanoylphorbol-13-acetate. The 5'-untranslated region of the 3.9-kilobase TIS10 message contains only 124 nucleotides, whereas the 3'-untranslated region is almost 2 kilobases in length. Within this long 3' region, there are multiple repeats of the sequence ATTTA, a sequence often present in rapidly degraded mRNA species. Primer extension revealed that the TIS10 cDNA begins 16 base pairs downstream of the transcription start site for the TIS10 gene. The TIS10 cDNA encodes a predicted protein of 604 amino acids. A computer search identified striking similarities between the predicted TIS10 protein product and the murine, sheep, and human prostaglandin synthase/cyclooxygenase proteins. The TIS10 protein has many of the same conserved amino acids that are thought to be important for cyclooxygenase function. TIS10 mRNA is undetectable by Northern analysis in quiescent 3T3 cells. The TIS10 gene is rapidly and transiently induced by forskolin and serum, as well as by 12-O-tetradecanoylphorbol-13-acetate, in Swiss 3T3 cells. These agents elicit far more dramatic changes in TIS10 mRNA levels than in cyclooxygenase mRNA levels. The expression of the TIS10 gene appears to be highly cell type-restricted in cultured cell lines; of 12 cell lines tested under superinducing conditions, only the rodent embryonic Swiss 3T3 and Rat1 cell lines expressed TIS10 gene.

Amino Acid Sequence↗
PubMed1979

Dexamethasone stimulation of metallothionein synthesis in HeLa cell cultures.

HeLa cells in culture synthesize metallothionein. To investigate the effects of glucocorticoids on metallothionein synthesis we adapted HeLa cells to growth in a defined medium lacking hydrocortisone. In this defined medium, containing 1.5 x 10(-6)M Zn2+, dexamethasone (10(-6)M) caused a five- to sixfold increase in the synthesis of metallothionein. Progesterone (10(-5)M), a known antagonist of glucocorticoids, inhibited this response by 50 percent.

Biological Transport↗
PubMed1978

Identification and characterization of a brain-specific antigen enriched in neonatal brain. I. Developmental, regional distribution and molecular weight studies.

An antiserum raised to the 20--40% ammonium sulfate cut of the soluble proteins extracted from whole neonatal rat brain has been absorbed with liver affinity columns. The absorbed antiserum recognizes a high molecular weight antigen(s) that is (i) restricted to nervous tissue, (ii) enriched in neonatal rat brain, and (iii) present from the 17th day of gestation throughout adult life. The name given to this brain-specific antigen(s) is NABSA, short for 'neonatal-associated brain-specific antigen'. NABSA is immunologically unrelated to S-100 or 14-3-2. NABSA levels in whole rat brain increased soon after birth. The specific activity of NABSA at 2--3 days postpartum reached 3--5-fold higher levels than are found in adult brain. NABSA declined to adult levels by the 10th postnatal day, well before CNS maturation was complete. Regional variations in NABSA levels were found in the rat neonate; highest activities occurred in neonatal cerebellum. Similar variations were observed in adult brain.

Age Factors↗
PubMed1978

Epidermal growth factor induced membrane changes in 3T3 cells.

Epidermal growth factor (EGF) is a mitogen for Swiss 3T3 cells. Short incubation periods with physiological concentrations of EGF induced increased binding of Swiss 3T3 cells to Con A-coated nylon fibers. This effect was not induced in an EGF non-responsive 33 variant, in the transformed murine XC cells or in Swiss SV3T3 cells. The increase in Con A fiber-binding seems to be specific for EGF, since it was not observed in response to insulin, prostaglandin F2alpha or a higher serum concentration, which also initiate cell devision of confluent quiescent 3T3 cells. EGF also reduced Con A-mediated hemadsorption to 3T3, but had no effect on hemadsorption by the EFG non-responsive 3T3 variant. There was no change in the number of Con A-receptors on 3T3 cells after EGF treatment. Binding to WGA-coated fibers and WGA-mediated hemadsorption were not effected by preincubation with EGF.

Clone Cells↗
PubMed1978

Mitogens for murine embryo cell lines.

The growth-promoting activities of fetal bovine serum, cortisol, phorbol myristate acetate, prostaglandin F2alpha, insulin, epidermal growth factor, and fibroblast growth factor were evaluated on four murine embryo cell lines (Swiss 3T3, Balb 3T3, M2, and C3H10T 1/2). Each cell has an unique response spectrum to this collection of reported mitogens. Phorbol myristate acetate and prostaglandin F2alpha were active only on selected cell lines; cortisol was inactive on all four lines. Serum, epidermal growth factor, and fibroblast growth factor were able to stimulate cell division in all four lines, albeit to varying degrees for the different target cells.

Animals↗
PubMed1978

Mitogenic response to epidermal growth factor: relationship to number, affinity, and down-regulation of EGF receptors in three murine embryo cell lines.

Swiss 3T3 and C3H-M2 cells have a greater mitogenic response to epidermal growth factor (EGF) than do C3H10T 1/2 cells. The latter cell line, however, has a number of EGF receptors per cell intermediate between the two cell lines that have a more vigorous response to EGF. Scatchard analysis of binding data indicate that all three cell lines have one class of EGF receptor, with indistinguishable affinity for the ligand. When exposed to 10-nM EGF all three cell lines "down-regulate" their EGF receptors with the same time course, and to the same percentage of initial receptors.

Cell Line↗
PubMed1978

Nerve growth factor-mediated induction of tyrosine hydroxylase in a clonal pheochromocytoma cell line.

We have established a clonal cell line, PC-G2, from an experimentally induced rat pheochromocytoma. Administration of nerve growth factor to PC-G2 causes a 4- to 8-fold induction in the specific activity of tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine,tetrahydropteridine:oxygen oxidoreductase(3-hydroxylating); EC 1.14.16.2]. The response is elicited in a dose-dependent fashion, at concentrations above 0.1 microgram/ml. Antiserum to nerve growth factor inhibited the induction of tyrosine hydroxylase. Dexamethasone enhances the nerve growth factor-mediated elevation of tyrosine hydroxylase. After 3--4 days of exposure to nerve growth factor the maximal induction of tyrosine hydroxylase is seen, although a significant increase can be observed after 24 hr. In contrast to the PC-12 cell line (derived from the same tumor), in which neurite outgrowth occurs in response to nerve growth factor, there is no morphological change or alteration in growth rate of PC-G2 cells after exposure to nerve growth factor.

Cell Line↗
PubMed1978

New neural cell lines derived from experimentally induced rat tumors and from human neuroblastomas.

We have isolated a series of new cell lines from tumors of the nervous system. Two approaches have been used. In the first, tumors were induced in neonatal rats with the potent carcinogen ethylnitrosourea. Tumors were put into cell culture and cloned after several passages. The resultant cell lines were characterized for a variety of presumptive neuronal and glial functions. Our second approach, designed to identify lines with neuronal characteristics, has been to culture and analyze cells derived from human neurolbastomas. Five lines have been characterized for the Na+ action potential ionophore and several enzyme markers.

Acetylcholine↗
PubMed1977

Specific radiolabeling of a cell surface receptor for epidermal growth factor.

A photoreactive derivative of epidermal growth factor (EGF) has been used to identify and specifically label a membrane receptor for EGF on mouse 3T3 cells. Photoactivable EGF, labeled with 125I, was incubated with 3T3 cells and then photolyzed in situ to generate a nitrene capable of reacting with a wide variety of chemical bonds. Analysis of the system by sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed, besides the band of EGF, only one other major radioactive band, at a position indicating an apparent molecular weight of 190,000. This band was absent when a nonresponsive and nonbinding variant of 3T3 was used. A direct proportionality between binding activity and crosslinked complex formation was demonstrated using a variety of binding conditions. "Down regulated" cells, in which EGF binding activity was greatly reduced by prolonged incubation with an appropriate concentration of EGF, also had a decrease in covalent complex formation proportional to the decrease in EGF binding activity.

Affinity Labels↗