Molecular cloning of gene sequences transcriptionally regulated by retinoic acid and dibutyryl cyclic AMP in cultured mouse teratocarcinoma cells

F9 mouse teratocarcinoma stem cells differentiate into primitive endoderm cells in response to retinoic acid (RA). A cDNA library, synthesized from RA and dibutyryl cyclic AMP-treated F9 teratocarcinoma cells, has been screened for gene sequences regulated by RA. By hybridization-selection and in vitro translation, the pcJ6, pcJ31, and pcF117 homologous mRNAs encode polypeptides of 40,000; 35,000-37,000; and 24,000 Da respectively. The pcI56 and pcI5 homologous mRNAs encode laminin B and collagen IV (S-Y. Wang and L. J. Gudas, 1983, Proc. Natl. Acad. Sci. USA 80, 5880-5884). Prior to RA addition, these gene sequences correspond to low-abundance mRNAs (less than 0.05% of total cellular mRNAs). Within 24 hr after the addition of RA (5 X 10(-7) M) to F9 cells, the expression of these sequences increases dramatically, and at 72 hr after drug addition, a 5- to 30-fold induction of these genes can be attained. Addition of lower concentrations of RA results in a smaller increase in the expression of these genes. If the F9 cells are treated with both RA (5 X 10(-7) M) and dibutyryl cyclic AMP (but2cAMP), the levels of mRNA specific for these five inducible genes are further increased by approximately 30- to 110-fold over those in the stem cells; but2cAMP alone does not induce the expression of these genes. The expression of J6 and J31, but not I56 (laminin) and 15 (collagen IV), is also regulated by RA in the P19 teratocarcinoma stem cell line, which differentiates into a fibroblastic cell type in response to RA. In vitro transcription experiments demonstrate that laminin and collagen IV are transcriptionally regulated by RA; but2cAMP also enhances the rate of transcription of these genes in F9 cells.

Butyrate inhibits the retinoic acid-induced differentiation of F9 teratocarcinoma stem cells

F9 mouse teratocarcinoma stem cells differentiate into parietal endoderm cells in the presence of retinoic acid, dibutyryl cyclic AMP, and theophylline (RACT). When F9 cells are exposed to 2-5 mM sodium butyrate plus RACT, they fail to differentiate. Differentiation is assessed by induction of laminin and collagen IV mRNA, the synthesis of laminin, collagen IV and plasminogen activator proteins, and alterations in cell morphology. Butyrate inhibits differentiation only when added within 8 hr after retinoic acid addition. Thus an early event in retinoid action on F9 cells is butyrate-sensitive. The population doubling time and cell cycle distribution of F9 cells are not altered within the first 24 hr after butyrate addition, suggesting that butyrate does not inhibit differentiation by inhibition of growth or normal cycling. However, butyrate does inhibit histone deacetylation in F9 cells, and this could be the mechanism by which butyrate inhibits differentiation.

Steroids. 2. Synthesis of C-18 functionalized steroids via the Smith-Hughes route

The total synthesis of a series of racemic C-18 functionalized steroids was carried out in a search for novel estrogen-and/or progestin-receptor agonists or antagonists. The target compound 3,18-dihydroxyestra-1,3,5(10)-triene (2), 13-(2-oxopropyl)gona-4-en-3-one (3), 13-(1-hydroxy-1-prop-2-ynyl)gona-4-en-3-one (4a and 4b) and 13-(1-acetoxy-2-oxo-1-propyl)gona-4-en-3-one (5) are position isomers of the highly biologically active estradiol, progesterone, norethindrone, and 17-acetoxyprogesterone, respectively. Nevertheless the synthetic C-18 functionalized steroids 3-5 showed little activity in the Clauberg and anti-Clauberg assays. Compound 2 showed no antagonism in the postcoital assay despite the fact that it exhibited weak but measurable in vitro receptor-binding activity.

Selection and characterization of F9 teratocarcinoma stem cell mutants with altered responses to retinoic acid

Retinoic acid induces the differentiation of many murine teratocarcinoma stem cell lines. To elucidate the molecular mechanism of action of retinoic acid, we have selected a series of mutants which exhibit altered differentiation responses to retinoic acid. All of the mutants display abnormal morphology following addition of 5 X 10(-7) M retinoic acid (RA) and dibutyryl cAMP. In addition, none of the mutants are resistant to the cytotoxic effects of higher concentrations of retinoic acid (greater than 75 microM). After the addition of retinoic acid, one mutant, RA-3-10, does not differentiate by any of the biochemical criteria we have used; this mutant also possesses less than 5% of the wild type level of cellular retinoic acid binding protein (CRABP). Other mutants, such as RA-3-3, RA-3-4, and RA-5-1, contain the same amount of CRABP as wild type F9 cells. However, the mutants RA-3-3 and RA-3-4 exhibit lower levels of plasminogen activator activity, and RA-3-4 also exhibits only 10-20% of the wild type synthesis and secretion of laminin and collagen IV following treatment with RA. After RA treatment of the mutant RA-5-1, laminin and collagen IV are synthesized and secreted at reduced rates relative to wild type cells, and the secreted collagen IV has a lower molecular weight than that of wild type; this suggests that RA-5-1 cells have a mutation in one of the enzymes responsible for post-translational modification of collagen IV. None of the mutants tested exhibits alterations in either cytosolic or membrane bound cAMP-dependent protein kinase activity. These studies provide genetic evidence that the CRABP is required for the differentiation of F9 teratocarcinoma stem cells by retinoic acid. However, even in the presence of CRABP, other types of alterations, such as synthesis of collagen IV with an abnormal molecular weight, appear to cause alterations in the differentiation response of cells to retinoic acid.

Isolation of cDNA clones specific for collagen IV and laminin from mouse teratocarcinoma cells

The synthesis of the proteins laminin and collagen IV is stimulated approximately equal to 20-fold in F9 mouse teratocarcinoma stem cells after treatment of the cells with retinoic acid and N6, O2'-dibutyryl-cAMP (Bt2cAMP). A cDNA library from F9 cells treated with retinoic acid, Bt2cAMP, and theophylline (F9-R + DBC cells) was constructed to isolate cDNA coding for collagen IV or laminin. The recombinant plasmids were screened by differential colony hybridization to cDNA synthesized from poly(A)+ RNA isolated from F9 stem and F9-R + DBC cells. Differentially hybridizing plasmids were then used as probes to hybridize to RNA transfer blots to determine the size of their specific mRNA. Only plasmids containing cDNA sequences specific for high molecular weight mRNA were further analyzed. Studies by hybridization-selection, in vitro translation, and immunoprecipitation showed that a plasmid clone, pc15, contains cDNA homologous to collagen IV (alpha 2) mRNA, and another plasmid clone, pc156, contains cDNA homologous to laminin B mRNA. By RNA blot analyses, the size of mRNA coding for collagen IV (alpha 2) is 7.6 kilobases; the size of mRNA for laminin is 6.8 kilobases. Using the technique of RNA blot hybridization, we studied the time course of the increase in mRNA coding for collagen IV (alpha 2) and laminin B in F9 cells after retinoic acid and Bt2cAMP treatment. Both collagen IV (alpha 2) and laminin B mRNAs are present in F9 stem cells. Collagen IV (alpha 2) mRNA and laminin B mRNA levels increase slightly at approximately 12 hr after retinoic acid and Bt2cAMP addition, with a dramatic increase between 12 and 24 hr after drug treatment.

Surface effects on Raman scattering from Sb deposited on Ag-island films

Surface-enhanced Raman scattering from crystal vibrational modes of a Sb film rather than from vibrational modes of individual molecules has been observed for the first time to our knowledge. A ~20x enhancement of the longitudinal-optical mode (150 cm(-1)) in the Raman spectra of crystalline Sb films deposited on silver-island films was obtained. The excitation profiles, as well as the dependence of Raman intensity on the thickness of Ag films, were studied.

Characterization of mast cell precursors by physical means: dissociation from T cells and T cell precursors

Murine bone marrow precursors (MCP) differentiate into mast cells and proliferate in response to mast cell growth factor (MCGF). An assay system based on the incorporation of [3']thymidine by proliferating mast cells in response to substantially purified MCGF was used to titrate MCP. Murine bone marrow was separated into fractions by Percoll density gradient centrifugation or velocity sedimentation at unit gravity. Individual fractions were analyzed to determine the relative concentrations of MCP. To determine if mast cells were derived from precursors different from those for T lymphocytes and granulocytes and macrophages, separated cells were also analyzed for responsiveness to interleukin 2 (IL 2) in standard [3H] thymidine incorporation assays and to granulocyte-macrophage colony stimulating factors (CSF) in agar cloning (CFU-GM) assays. Cultured marrow cells from Dexter type long-term marrow cultures (LMC) were included as a source of marrow cells devoid of mature T cells, so as to dissociate MCP from pre-T cells. MCP were readily dissociable from T cells and/or pre-T cells present in fresh, as well as cultured, marrow cells by either density or velocity of sedimentation separation techniques. MCP were, however, not readily separable from CFU-GM. Nevertheless, MCP appeared not to share a common precursor with pure macrophage type colony-forming cells (CFU-M phi). The implications of the findings on the lineage origin of mast cells were discussed.

Characterization of mast cell precursors by physical means: dissociation from T cells and T cell precursors

Murine bone marrow precursors (MCP) differentiate into mast cells and proliferate in response to mast cell growth factor (MCGF). An assay system based on the incorporation of [3']thymidine by proliferating mast cells in response to substantially purified MCGF was used to titrate MCP. Murine bone marrow was separated into fractions by Percoll density gradient centrifugation or velocity sedimentation at unit gravity. Individual fractions were analyzed to determine the relative concentrations of MCP. To determine if mast cells were derived from precursors different from those for T lymphocytes and granulocytes and macrophages, separated cells were also analyzed for responsiveness to interleukin 2 (IL 2) in standard [3H] thymidine incorporation assays and to granulocyte-macrophage colony stimulating factors (CSF) in agar cloning (CFU-GM) assays. Cultured marrow cells from Dexter type long-term marrow cultures (LMC) were included as a source of marrow cells devoid of mature T cells, so as to dissociate MCP from pre-T cells. MCP were readily dissociable from T cells and/or pre-T cells present in fresh, as well as cultured, marrow cells by either density or velocity of sedimentation separation techniques. MCP were, however, not readily separable from CFU-GM. Nevertheless, MCP appeared not to share a common precursor with pure macrophage type colony-forming cells (CFU-M phi). The implications of the findings on the lineage origin of mast cells were discussed.

Differential responsiveness of avian vitellogenin I and vitellogenin II during primary and secondary stimulation with estrogen

Avian vitellogenin consists of two major species, VTG I and VTG II, which show major differences in structure and immunological properties suggesting that VTG I and VTG II are distinct gene products. During primary stimulation with estrogen, VTG I was found to accumulate in plasma much more slowly than VTG II. At 1 day after hormone treatment VTG I was only 1-3% of VTG II, but by day 5 VTG I increased to approximately 25% of VTG II. Measurements of hepatic vitellogenin synthesis confirmed the slower induction and reduced expression of VTG I. A further difference was noted in the amnestic or memory response to secondary estrogen treatment. Measurements of VTG I and VTG II accumulation and synthesis after primary and secondary estrogen treatment showed that the memory response occurs to a much greater extent for VTG I than VTG II. These differences indicate that the inductions of VTG I and VTG II are not tightly coupled.

Isolation and characterization of a cDNA clone specific for avian vitellogenin II

A clone for vitellogenin, a major avian, estrogen responsive egg yolk protein, was isolated from the cDNA library of estrogen-induced rooster liver. Two forms of plasma vitellogenin, vitellogenin I (VTG I) and vitellogenin II (VTG II), distinguishable on the basis of their unique partial proteolysis maps, have been characterized and their corresponding hepatic precursor forms identified. We have used this criterion to specifically characterize which vitellogenin protein had been cloned. Partial proteolysis maps of BTG I and VTG II standards, synthesized in vivo, were compared to maps of protein synthesized in vitro using RNA hybrid-selected by the vitellogenin plasmid. Eight major digest fragments were found common to the in vitro synthesized vitellogenin and the VTG II standard while no fragments were observed to correspond to the VTG I map. A restriction map of the VTG II cDNA clone permits comparison to previously described cDNA and genomic vitellogenin clones.

Recycling of 5'-methylthioadenosine-ribose carbon atoms into methionine in tomato tissue in relation to ethylene production

The ribose moiety of 5'-methylthioadenosine (MTA) is metabolized to form the four-carbon unit (2-aminobutyrate) of methionine in tomato tissue (Lycopersicon esculentum Mill., cv. Pik Red). When [U-(14)C-adenosine] MTA was administered to tomato tissue slices, label was recovered in 5-methylthioribose (MTR), methionine, 1-aminocyclopropane-1-carboxylic acid (ACC), C(2)H(4) and other unidentified compounds. However, when [U-(14)C-ribose]MTR was administered, radioactivities were recovered in methionine, ACC and C(2)H(4), but not MTA. This suggests that C(2)H(4) formed in tomato pericarp tissue may be derived from the ribose portion of MTA via MTR, methionine and ACC. The conversion of MTR to methionine is not inhibited by aminoethoxyvinylglycine (AVG), but is O(2) dependent. These data present a new salvage pathway for methionine biosynthesis which may be important in relation to polyamine and ethylene biosynthesis in tomato tissue.

Influence of calcium and magnesium on ethylene production by apple tissue slices

The decline in ethylene production in apple (Pyrus malus L. cv. Golden Delicious) tissue slices during 24 hours incubation in 600 millimolar sorbitol and 10 millimolar 2-(N-morpholino)ethanesulfonic acid buffer (pH 6.0) is recognized as a senescent phenomenon. The inclusion of very high concentrations (100 millimolar) of Ca(2+), Mg(2+), or Ca(2+) plus Mg(2+) severely inhibited ethylene production during the first 6 hours of incubation. However, after 6 hours and up to 24 hours the ethylene-forming system was stablized. These high concentrations of Ca(2+), Mg(2+), or Ca(2+) plus Mg(2+) virtually eliminated lipid peroxidation and protein leakage from these slices. Also conversion of 1-aminocyclopropane-1-carboxylic-1-acid to ethylene and the influence of indoleacetic acid on ethylene production was stabilized after 24 hours of incubation by these high concentrations of Ca(2+), Mg(2+), and Ca(2+) plus Mg(2+). Addition of divalent ionophores severely inhibited ethylene production, but this inhibition was prevented by Ca(2+) in concentrations greater than the ionophore. These data suggest that the loss of ethylene production by aging tissue slices results from degradation of membranes. They support previous work that indicates that the ethylene-forming system, perhaps the segment of the pathway from 1-aminocyclo-propane-1-carboxylic-1-acid to ethylene, resides in the plasma membrane.

Biosynthesis of the vitellogenins. Identification and characterization of nonphosphorylated precursors to avian vitellogenin I and vitellogenin II

Avian vitellogenin consists of two major species designated VTG I and VTG II. Rooster hepatocytes were employed to identify intracellular forms of the vitellogenins and to characterize biosynthetic intermediates of VTG I and VTG II. After labeling with [3H]serine, intracellular vitellogenin radioactivity was seen in mature VTG I and VTG II but was primarily found in two species, pVTG I and pVTG II, which showed greater mobilities in sodium dodecyl sulfate-polyacrylamide gels. The pVTG species were identified as vitellogenins by reaction with antibodies against plasma VTG II and against the mixture of VTG I and VTG II. Immunological and peptide mapping procedures were used to relate pVTG I and pVTG II to secreted VTG I and VTG II, respectively. Pulse-labeling and pulse-chase experiments showed that the pVTG species are precursors to the secreted vitellogenins and are thus discrete intermediates in the biosynthesis of the vitellogenins. Additional labeling experiments showed that the pVTG species are glycosylated but not phosphorylated. The stages of vitellogenin biosynthesis may be ordered as follows: polypeptide synthesis leads to glycosylation leads to phosphorylation leads to secretion. The presence of only small quantities of the phosphorylated vitellogenins intracellularly indicates that when phosphorylation is completed, the vitellogenins are rapidly secreted from the hepatocyte. The differences in the electrophoretic mobilities of the pVTG and VTG species suggested that sodium dodecyl sulfate-polyacrylamide gel electrophoresis does not accurately estimate the molecular weights of the heavily phosphorylated vitellogenins. This was confirmed directly by showing that the mobility of plasma vitellogenin increased upon dephosphorylation. An independent estimate of vitellogenin molecular weight was made by gel chromatography in 7 M guanidine-HCl. With this method, the molecular weights of the pVTG and VTG species were indistinguishable and in agreement with the molecular weight of the pVTG species as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These analyses indicate that the vitellogenin polypeptide has Mr approximately equal to 180,000. This value is 60,000-70,000 less than commonly estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The implications of this lower molecular weight are discussed in relation to vitellogenin structure and the egg yolk polypeptides which may derive from each vitellogenin.

Malignant carcinoid tumor metastatic to a meningioma

Postmortem examination in a patient with a widely disseminated pulmonary carcinoid tumor revealed invasion of a fibroblastic meningioma by metastatic tumor cells. To the authors' knowledge, this case represents the first example of a malignant carcinoid tumor that has metastasized to a primary intracranial neoplasm. The literature concerning metastasis of extracranial to primary intracranial tumors is briefly reviewed.

Inhibition of the Conversion of 1-Aminocyclopropane-1-carboxylic Acid to Ethylene by Structural Analogs, Inhibitors of Electron Transfer, Uncouplers of Oxidative Phosphorylation, and Free Radical Scavengers

Cyclopropane carboxylic acid (CCA) at 1 to 5 millimolar, unlike related cyclopropane ring analogs of 1-aminocyclopropane-1-carboxylic acid (ACC) which were virtually ineffective, inhibited C(2)H(4) production, and this inhibition was nullified by ACC. Inhibition by CCA is not competitive with ACC since there is a decline, rather than an increase, in native endogenous ACC in the presence of CCA. Similarly, short-chain organic acids from acetic to butyric acid and alpha-aminoisobutyric acid inhibited C(2)H(4) production at 1 to 5 millimolar and lowered endogenous ACC levels. These inhibitions, like that of CCA, were overcome with ACC. Inhibitors of electron transfer and oxidative phosphorylation effectively inhibited ACC conversion to C(2)H(4) in pea and apple tissues. The most potent inhibitors were 2,4-dinitrophenol (DNP) and carbonyl cyanide m-chlorophenylhydrazone (CCCP) which virtually eliminated ACC-stimulated C(2)H(4) production in both tissues. Still other inhibitors of the conversion of ACC to C(2)H(4) were putative free radical scavengers which reduced chemiluminescence in the free radical-activated luminol reaction. These inhibitor studies suggest the involvement of a free radical in the reaction sequence which converts ACC to C(2)H(4). Additionally, the potent inhibition of this reaction by uncouplers of oxidative phosphorylation (DNP and CCCP) suggest the involvement of ATP or the necessity for an intact membrane for C(2)H(4) production from ACC. In the latter case, CCCP may be acting as a proton ionophore to destroy the membrane integrity necessary for C(2)H(4) production.

Ethylene production by callus and suspension cells from cortex tissue of postclimacteric apples

Cortex tissue from postclimacteric ;Golden Delicious' apples (Malus domestica, Borkh.) stored at 0 C for 9 months after harvest were induced to form callus in vitro. Cell suspension cultures were subsequently formed from calli. Of five media tested, only the medium of Schenk and Hildebrandt (Can J Bot 1972, 50: 192) and that of Uchimiya and Murashige (Plant Physiol 1974, 54: 936) allowed callus formation. During growth both the callus and cell cultures produced ethylene in a pattern which showed a rapid rise and then a fall as the culture grew. (14)C-Labeled methionine was converted to labeled ethylene by the cell suspension cultures, which also could be inhibited from producing ethylene by a rhizobitoxine analog or free radical scavengers. Ethylene production in these cultures, like that in intact fruit tissue slices, could be stimulated by IAA or suppressed by N(6)-(gamma,gamma-dimethylallyl) adenosine and GA(3).

Metastatic lymphoma in the ureter complicated by bacteremia and fungemia

A 64-year-old woman presented with retroperitoneal lymphoma metastatic to the left ureter. Lymphoma was not diagnosed and her clinical course was not fully explained until after surgery. The lack of superficial lymphoma delayed diagnosis and therefore prevented effective treatment. Her situation became unmanageable when it was complicated by bacteremia (E coli) and fungemia (Candida albicans).

Decrease in functional albumin mRNA during estrogen-induced vitellogenin biosynthesis in avian liver

Translation of rooster liver RNA in a wheat germ extract is shown to yield albumin as one of the cell-free products. Quantitation of albumin mRNA by the translation assay indicates that functional albumin mRNA represents 10% of total liver mRNA activity in control roosters. After estrogen administration, this level decreases in a continuous fashion until functional albumin mRNA represents 5% of total mRNA activity at 12 days. This decrease in functional albumin mRNA was correlated with several parameters of vitellogenin induction. Functional vitellogenin mRNA increases to a maximum at 4 days after hormone treatment and returns to control levels by 12 days. A similar pattern is seen for the hormone-stimulated increase in total mRNA activity. The decrease in functional albumin mRNA, therefore, persists after the vitellogenic response of the liver has been completed. These results suggest that the decrease in hepatic albumin synthesis after hormone treatment is due to an estrogen-mediated decrease in the content of albumin mRNA.

Effects of ultrasound on nucleic acid bases

To understand the effects of ultrasound in biological systems at the molecular level, sonolysis of nucleic acid bases at sonic intensities less than or equal to 5 W/cm2 was studied. These sonoreactions were followed by UV-spectral decrease and by sonoproduct analysis. The order of reactivity was found to be thymine greater than uracil greater than cytosine greater than guanine greater than adenine. The extent of sonoreactions depends on the exposure time and the rate of the intensity. Aeration was necessary for maintenance of a reasonable reaction rate. "Threshold" intensities for uracil and thymine were observed at approximately 0.5 W/cm2. The effectiveness of the dissolved gases in producing sonoreactions was Ar greater than 02 greater than air greater than N2 greater than He greater than N2O, suggestive of free radicals mediating these reactions since N2O is an effective radical scavenger. Studies of the effects of substituents have shown that electronic rather than steric effects may have a greater influence. Preliminary identification indicates that cis- and trans-uracil glycols are the major products of uracil. Thus, a stepwise mechanism of pyrimidine sonolysis is proposed. Sonolysis of a dilute aqueous solution of uracil yielded pseudo-first-order kinetics in terms of [Ura] with a rate constant of 3.9 X 10(-2) min-1, implying that the rate-limiting step is the reaction of HO- with the base.

Genetic variation in the RNA transcripts of endogenous virus genes in uninfected chicken cells

Uninfected cells from two different phenotypes of chicken embryos express significant amounts of endogenous viral information, though they do not produce virus particles. Cells of the phenotype gs(+)chf(+) are positive for both group-specific (gs) antigens and chicken helper factor (chf) activity, whereas cells of a second phenotype, gs(L)chf(+)(h(E)), demonstrate noncoordinate expression of these two viral activities (very low amounts of gs antigens, but extremely high helper activity). RNA from these cells was analyzed to determine the size, genetic content, and relative abundance of virus-specific RNAs in cells of each phenotype. Two major size classes of polyadenylic acid-containing RNA, homologous to the avian leukosis virus genome, were detectable in cells of both types. The larger RNA, which contained most of the sequences of the leukosis virus genome, was of different sizes in the two phenotypes, 31S in gs(+)chf(+) cells but 35S in the noncoordinate cell type. Analysis of the viral RNA with gene-specific complementary DNA probes revealed the following characteristics. (i) The 31S RNA appeared to lack portions of the gag and pol genes. (ii) A smaller RNA species, which sedimented at 21S in both cell types, was a transcript of the 3'-proximal portion of the viral genome, consisting of the env gene and the "common" sequences. (iii) The amount of env-specific RNA in the 21S region was more than six times higher in the noncoordinate cell type than in the gs(+)chf(+) cells; this difference was concordant with the 5- to 10-fold higher chf activity in the noncoordinate cells. (iv) The endogenous viral RNA in uninfected cells and the RNA from Rous-associated virus-0 virions hybridized only partially with DNA complementary to the common region of the Rous-associated virus-2 genome, whereas the RNA of all exogenous viruses tested hybridized almost completely to this complementary DNA. Small amounts of src-specific polyadenylated RNA were also present in uninfected chicken cells. This RNA sedimented as a single peak at 26S and was not covalently linked to any other identifiable virus-specific RNA sequences. The amount of src RNA was the same in the above two types of expression-positive cells and also in cells that were gs(-)chf(-), indicating that the transcription of the cellular sequences homologous to the src gene is independent of the transcription of the other endogenous viral genes.