Le récepteur de l'oestradiol, l'AMP cyclique et la RNA polymérase nucléolaire dans l'utérus de génisse

Antigenic Proteins of Nucleolar Chromatin of Novikoff Hepatoma Ascites Cells

Nucleolar chromatin of Novikoff hepatoma ascites cells contains an antigen (no-Ag1) detected with antinucleolar antibodies by the immunodiffusion technique. This antigen was distinguished from the previously reported nuclear chromatin antigen NAg-1 (19) by the findings that tumor nucleolar antibodies which formed immunoprecipitin bands with no-Ag1 did not do so with NAg-1 and that tumor cytosol, which contains NAg-1, formed immunoprecipitin bands with tumor chromatin antibodies but not with antibodies to tumor nucleoli. Tumor nucleolar chromatin contains both NAg-1 and no-Ag1, but only no-Ag1 formed bands with tumor nucleolar antibodies. no-Ag1 is a component of tumor nucleolar chromatin that was not soluble in 0.075 M NaCl - 0.025 M EDTA, pH 8, and only slightly soluble in 0.01 M Tris-HCl, pH 8. no-Ag1 was not found in liver nucleoli. Antibodies to liver nucleoli formed immunoprecipitin bands with liver nucleolar antigens but none were confluent with those formed between tumor nucleolar antibodies and antigens of tumor nucleolar chromatin. Absorption of the tumor nucleolar antibodies with whole tumor cells or whole liver pressate did not alter band formation with no-Ag1. Three antigens in liver nucleoli were not found in tumor nucleoli.

Neurotransmitter modulation of steroid action in target cells that mediate reproduction and reproductive behavior

Two major functional interactions between steroid hormones and neurotransmitters are generally recognized. First, steroids affect neurotransmission, and second, through effects on hypothalamic peptides that regulate anterior pituitary function neurotransmitters affect steroid secretion. In recent years, evidence has accumulated which indicates that neurotransmitters can also affect steroid action within postsynaptic steroid target cells. We review evidence for this relationship in pineal, uterus and hypothalamus and propose that the modulation of target cell responsiveness to steroids is an important mechanism by which neurotransmitters affect steroid-dependent processes. The operation of such a mechanism provides a means for environmental, behavioral and emotional events to rapidly and selectively alter steroid effects on behavior and physiology.

Cisplatin: chemistry, distribution and biotransformation

A review of the use of cisplatin in cancer chemotherapy in humans is presented. The emphasis is placed on the chemistry, in vivo distribution and biotransformation of this agent. The existing literature pertinent to the physicochemical properties of cisplatin and structure activity relationships of platinum coordination complexes is reviewed. The chemistry of this drug, both in aqueous media and in biological systems is discussed as well as current analytical methodology used for monitoring 'cisplatin levels' in biological fluids. Recent advances in analytical methodology specific for cisplatin are also presented and recent findings in the area of the possible biotransformations of this important anticancer agent are discussed.

Specific regulation by steroid hormones of protein kinases in the endometrium. 2. Alteration in levels of protein kinases in human endometrium during the menstrual cycle

The alteration in the levels of multiple protein kinases has been studied in human endometrium during the menstrual cycle. Protein kinases were examined in the cytosol fraction and separated by DEAE-cellulose column chromatography. The level of type I adenosine 3',5'-monophosphate-dependent (cAMP-dependent) protein kinase was higher than that of type II cAMP-dependent protein kinase at the proliferative phase. At the late secretory phase, type I cAMP-dependent protein kinase markedly decreased, whereas type II cAMP-dependent protein kinase remained at the same level. Therefore, type II cAMP-dependent protein kinase was exclusively predominant at this phase. cAMP-dependent and cAMP-independent protein kinases with protamine increased more at the late secretory phase than at the proliferative phase. The results presented demonstrate a specific alteration in protein kinase activities during the menstrual cycle and are compatible with those obtained in rabbit endometrium (the preceding paper).

Physiologic significance of 17beta-estradiol binding in the rabbit Fallopian tube

Rabbit Fallopian tube contractility was recorded in vitro during perfusion with either Locke's solution or that solution containing CN-55, 945-27 (CN; or CI-628), a nonsteroidal estrogen antagonist (Endocrinology 79: 153, 1966). Contractility was inhibited and 17beta-estradiol (E2) displaced from both its cytoplasmic (8S) and nuclear (4S) receptors in the presence of the above agent. These effects result from a direct interaction between CN and the E2-receptor complexes. Two types of evidence show the specificity of the foregoing responses: (1) nonspecific binding of E2 to serum proteins was unaffected by the antagonist and (2) CN had no effect on contractility of a nontarget tissue, i.e., rabbit ileum. In addition, Fallopian tube contractions induced by strong electrical stimulation of K-depolarized tissues (i.e., in the absence of normal ionic gradients) were inhibited by CN and a decrease in the binding capacities of 8S and 4S receptors was again observed. Thus, antagonism of specific E2 binding inhibits the contractile mechanism at a level other than the cell membrane. These observations, and additional findings concerning the reversibility of CN action, indicate that E2 binding is essential for contractility of the rabbit Fallopian tube.

Solubilized DNA-dependent nuclear RNA polymerases from the mammary glands of late-pregnant rats

Mammary gland nuclear extracts from late-pregnant Wistar or Sprague-Dwaley rats, analyzed by DEAE-Sephadex chromatography, were found to contain DNA-dependent RNA polymerases, cyclic nucleotide-binding proteins, and cyclic AMP-independent protein kinases. 1. The fractions from chromatographed nuclear extracts which contained nucleolar enzymes or nucleoplasmic enzyme II, bound radioactive cyclic AMP and cyclic GMP. Other fractions also bound cyclic nucleotides, some preferentially associating with one or the other compound. 2. Cyclic AMP increased the amount of RNA formed by several alpha-amanitin-insensitive fractions containing nucleolar enzymes. 3. Cyclic AMP reduced the amount of RNA formed by column fractions which included nucleoplasmic enzyme II. 4. Cyclic GMP increased the amount of RNA synthesized by column fractions containing enzyme II. 5. Two major cyclic AMP-independent protein kinases which did not elute with enzymes Ib and II, and several minor protein kinases were present. These findings may have important implications for understanding the proximate control of transcription. A relationship between them is not established, but is under study.

Female steroid hormones and target cell nuclei

The data discussed herein demonstrate the great variation in target-tissue response that can occur after administration of steroid hormones. The female sex steroids can exert regulatory effects on the synthesis, activity, and possibly even the degradation of tissue enzymes and structural proteins. Each response, nevertheless, appears to be dependent on the synthesis of nuclear RNA. In many instances, the steroid actually promotes a qualitative change in the base composition and sequence of the RNA synthesized by the target cell, implying a specific effect on gene transcription. Most important is our direct quantitative evidence that sex steroids cause a net increase in the intracellular amounts of specific mRNA molecules in target tissues. It thus appears that we are discovering a pattern of steroid hormone action which includes (Fig. 1): (i) uptake of the hormone by the target cell and binding to a specific cytoplasmic receptor protein; (ii) transport of the steroid-receptor complex to the nucleus; (iii) binding of this "active" complex to specific "acceptor" sites on the genome (chromatin DNA and acidic protein); (iv) activation of the transcriptional apparatus resulting in the appearance of new RNA species which includes specific mRNA's; (v) transport of the hormone-induced RNA to the cytoplasm resulting in synthesis of new proteins on cytoplasmic ribosomes; and (vi) the occurrence of the specific steroid-mediated "functional response" characteristic of that particular target tissue. To elucidate fully the mechanism of steroid hormone action we must study the biochemistry of the process by which information held by the steroid hormone-receptor complex is transferred to the nuclear transcription apparatus. If our assumptions are correct, we should ultimately be able to discover how this hormone-receptor complex exerts a specific regulatory effect on nuclear RNA metabolism. Such regulation might be achieved (i) by direct effects on chromatin template leading to increased gene transcription and thus RNA synthesis; (ii) by activation of the polymerase complex itself; (iii) by inhibition of RNA breakdown; or (iv) by intranuclear processing of large precursor molecules so that smaller biologically active sequences are produced, and (v) by transport of RNA from the nucleus to the cytoplasmic sites of cellular protein synthesis.