PRL is an anterior pituitary hormone that, along with GH and PLs, forms a family of hormones that probably resulted from the duplication of an ancestral gene. The PRLR is also a member of a larger family, known as the cytokine class-1 receptor superfamily, which currently has more than 20 different members. PRLRs or binding sites are widely distributed throughout the body. In fact, it is difficult to find a tissue that does not express any PRLR mRNA or protein. In agreement with this wide distribution of receptors is the fact that now more than 300 separate actions of PRL have been reported in various vertebrates, including effects on water and salt balance, growth and development, endocrinology and metabolism, brain and behavior, reproduction, and immune regulation and protection. Clearly, a large proportion of these actions are directly or indirectly associated with the process of reproduction, including many behavioral effects. PRL is also becoming well known as an important regulator of immune function. A number of disease states, including the growth of different forms of cancer as well as various autoimmune diseases, appear to be related to an overproduction of PRL, which may act in an endocrine, autocrine, or paracrine manner, or via an increased sensitivity to the hormone. The first step in the mechanism of action of PRL is the binding to a cell surface receptor. The ligand binds in a two-step process in which site 1 on PRL binds to one receptor molecule, after which a second receptor molecule binds to site 2 on the hormone, forming a homodimer consisting of one molecule of PRL and two molecules of receptor. The PRLR contains no intrinsic tyrosine kinase cytoplasmic domain but associates with a cytoplasmic tyrosine kinase, JAK2. Dimerization of the receptor induces tyrosine phosphorylation and activation of the JAK kinase followed by phosphorylation of the receptor. Other receptor-associated kinases of the Src family have also been shown to be activated by PRL. One major pathway of signaling involves phosphorylation of cytoplasmic State proteins, which themselves dimerize and translocate to nucleus and bind to specific promoter elements on PRL-responsive genes. In addition, the Ras/Raf/MAP kinase pathway is also activated by PRL and may be involved in the proliferative effects of the hormone. Finally, a number of other potential mediators have been identified, including IRS-1, PI-3 kinase, SHP-2, PLC gamma, PKC, and intracellular Ca2+. The technique of gene targeting in mice has been used to develop the first experimental model in which the effect of the complete absence of any lactogen or PRL-mediated effects can be studied. Heterozygous (+/-) females show almost complete failure to lactate after the first, but not subsequent, pregnancies. Homozygous (-/-) females are infertile due to multiple reproductive abnormalities, including ovulation of premeiotic oocytes, reduced fertilization of oocytes, reduced preimplantation oocyte development, lack of embryo implantation, and the absence of pseudopregnancy. Twenty per cent of the homozygous males showed delayed fertility. Other phenotypes, including effects on the immune system and bone, are currently being examined. It is clear that there are multiple actions associated with PRL. It will be important to correlate known effects with local production of PRL to differentiate classic endocrine from autocrine/paracrine effects. The fact that extrapituitary PRL can, under some circumstances, compensate for pituitary PRL raises the interesting possibility that there may be effects of PRL other than those originally observed in hypophysectomized rats. The PRLR knockout mouse model should be an interesting system by which to look for effects activated only by PRL or other lactogenic hormones. On the other hand, many of the effects reported in this review may be shared with other hormones, cytokines, or growth factors and thus will be more difficult to study. (ABSTRACT TRUNCATED)

Prolactin (PRL) and Its Receptor: Actions, Signal Transduction Pathways and Phenotypes Observed in PRL Receptor Knockout Mice

A method for isolation of large, translationally active RNA species is presented. The procedure involves homogenization of cells or tissues in 5 m guanidine monothiocyanate followed by direct precipitation of RNA from the guanidinium by 4 m LiCl. Modifications are described for use with tissue culture cells, yeast, tissues, or isolated nuclei. The advantages of the procedure include speed, simplicity, avoidance of an ultracentrifugation, and its applicability to large numbers of small samples. The procedure yields large mRNA precursors up to 10 kb and mRNA species which translate very well. However, small (<300 nucleotides) RNA species are recovered with a poor yield.

A Method for Isolation of Intact, Translationally Active Ribonucleic Acid

Introduction STEROID hormones are familiar clinically and physiologically as regulators of physiological processes. Five groups of steroid hormones are generally recognized according to their physiological behavior: mineralocorticoids, which instruct the renal tubules to retain sodium; glucocorticoids, which are named for their carbohydratemobilizing properties but have many other effects as well; estrogens, which induce female secondary sexual characteristics; progestins, which are essential for reproduction; and androgens, which induce male secondary sexual characteristics. These classes of steroid hormones are structurally similar and arise from a common series of pathways. They are distinguished by their actions on one or more specific steroid hormone receptors. The hormone/receptor complexes function as tissue-specific transcriptional regulators of distinct domains of genes and, consequently, exert their broad array of physiological effects. (For reviews, see Refs. 1 and 2.) The pathways by which the...

Molecular Biology of Steroid Hormone Synthesis

A method for producng a recombinant baculovirus expression vector, capable of expressing a selected gene in a host insect cell, is disclosed. The method involves cleaving baculovirus DNA to produce a DNA fragment comprising a polyhedrin gene or portion thereof, including a polyhedrin promoter. A recombinant transfer vector is prepared by inserting said DNA fragment into a cloning vehicle and thereafter inserting a selected gene into the thus modified cloning vehicle such that it is under the transcriptional control of the polyhedrin promoter. The recombinant transfer vector is contacted with a baculovirus DNA so as to effect recombination and incorporation of the selected gene into the baculovirus genome. The resultant recombinant baculovirus is then used to infect susceptible insects or cultured insect cells and the protein product from the incorporated selected gene is produced from the infection.

Method for producing a recombinant baculovirus expression vector

The invention provides novel human transmembrane (NOVTRAN), neuromedin (NOVNEUR), gonadtropih (NOVGON), and interleukin-1 receptor antagonist (NOVINTRA A and B) proteins (NOVX proteins) and isolated nucleic acid molecules encoding the same. Also provided are antibodies that immunospecifically bind to NOVX polypeptides or polynucleotides, or derivatives, variants, mutants, or fragments thereof. The invention additionally provides methods in which a NOVX polypeptide, polynucleotide, and antibody are used in the detection, prevention, and treatment of a broad range of pathological states. Also provided are method of diagnosing and treating a lung disease associated with differential expression of human interleukin-1 epsilon.

Novel Proteins and nucleic acids encoding the same

Prolactin, growth hormone, and chorionic somatomammotropin (placental lactogen) constitute a set of related polypeptides believed to derive from a common evolutionary ancestor protein. We have cloned and sequenced DNA complementary to the mRNA coding for bovine prolactin. This cDNA contains 702 bases corresponding to 10 amino acids in the leader peptide, all 199 amino acids of the hormone, and 75 nucleotides in the 3' untranslated region of the mRNA. Nucleotide sequence analysis of this cDNA permitted the identification of 10 amino acids in the signal peptide, plus the correction or elucidation of amino acid assignments at 16 sites where aspartic and glutamic acids had not been distinguished from their amides by amino acid sequencing. Codon usage in bovine prolactin mRNA is nonrandom, but, similarly to rat and human prolactins, it does not exhibit the strong preference for G or C in codon third positions seen in bovine, rat, and human growth hormone mRNAs. The translational termination signal in bovine prolactin in UAA, also the same as in rat and human prolactins and differing from the UAG "stop" codon used in bovine, rat, and human growth hormones and human chorionic somatomammotropin. The amino acid and mRNA nucleotide sequences of bovine, rat, and human prolactins and growth hormones were compared by several techniques based on various theories of molecular evolution. The comparison of prolactin to growth hormone is consistent in all three species, suggesting that the genes for these two hormones diverged about 350 million years ago. However, comparisons among the three prolactins or among the three growth hormones to determine the times of evolutionary divergence of the three species generated values that were inconsistent with each other and with the fossil record. Analysis of these discrepancies suggests that the genes for prolactin and growth hormone may now be evolving by different mechanisms.

Cloning of bovine prolactin cDNA and evolutionary implications of its sequence.

Production of growth hormone by cultured rat pituitary tumor cells (GH3 subline) is regulated by hormones. In previous studies, it was shown that thyroid and glucocorticoid hormones stimulate growt...

Hormonal Regulation of Growth Hormone mRNA

Publisher Summary
This chapter describes the importance of thyroid hormones in the regulation of gene expression. Thyroid hormones have remarkable effect on differentiation and development in vertebrates. In man, for example, the lack of thyroid hormones can result in severe developmental deficiencies in the central nervous and skeletal systems. Thyroid hormones also have noticeable influence on metabolism in adults. The studies so far specify that hormones influence a number of gene products; in fact, changes in the levels of certain proteins and enzymes are known to account at least in part, for particular physiological responses to the hormone. Additionally, the finding of intranuclear receptors whose characteristics are suggestive of their involvement in thyroid responses has also directed attention to the nucleus as a potential site of thyroid hormone regulation. The chapter also describes thyroid hormone binding components in other cellular fractions. High-affinity and limited-capacity thyroid hormone binding components have also been identified in the cytosol, mitochondria, and membrane fractions. The properties of the cytosol binders have shown considerable variation as reported in different tissues. For example, the cytosol binding proteins in cultured pituitary cells have a higher affinity for thyroxine than for triiodothyronine.

Regulation of gene expression by thyroid hormones

DNA comprising the naturally occurring nucleotide sequence coding for amino acids 44-90 of β-lipotropin and including the entire coding region for β-endorphin with the exception of the C-terminal glutamine was modified, transferred to an expression transfer vector, and expressed as a fusion protein. The fusion protein was further modified in vitro to yield mature β-endorphin. β-endorphin was purified from a bacterial lysate. The structure and biological activity of the resulting product was proven by immunological assay, and by two independent assays designed to demonstrate biological activity.

MICROBIOLOGICAL SYNTHESIS OF .beta. ENDORPHIN

In cultured rat pituitary cells, glucocorticoids regulate growth hormone production by modulating the number of growth hormone messenger RNA molecules. The effect is quite specific, since only a few other mRNAs are affected by the hormones. This response is demonstrated by assays involving cell-free mRNA translation and cDNA-RNA hybridization. Furthermore, the inducibility by the glucocorticoids is regulated by at least one other class of hormones, thyroid hormone. Thus, this system serves as a model for studying not only the glucocorticoid regulation of specific mRNA, but also the control of this regulation by other factors in the target tissue.

Regulation of growth hormone messenger RNA.

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