Prostate response to prolactin in sexually active male rats

BACKGROUND: The prostate is a key gland in the sexual physiology of male mammals. Its sensitivity to steroid hormones is widely known, but its response to prolactin is still poorly known. Previous studies have shown a correlation between sexual behaviour, prolactin release and prostate physiology. Thus, here we used the sexual behaviour of male rats as a model for studying this correlation. Hence, we developed experimental paradigms to determine the influence of prolactin on sexual behaviour and prostate organization of male rats. METHODS: In addition to sexual behaviour recordings, we developed the ELISA procedure to quantify the serum level of prolactin, and the hematoxilin-eosin technique for analysis of the histological organization of the prostate. Also, different experimental manipulations were carried out; they included pituitary grafts, and haloperidol and ovine prolactin treatments. Data were analyzed with a One way ANOVA followed by post hoc Dunnet test if required. RESULTS: Data showed that male prolactin has a basal level with two peaks at the light-dark-light transitions. Consecutive ejaculations increased serum prolactin after the first ejaculation, which reached the highest level after the second, and started to decrease after the third ejaculation. These normal levels of prolactin did not induce any change at the prostate tissue. However, treatments for constant elevations of serum prolactin decreased sexual potency and increased the weight of the gland, the alveoli area and the epithelial cell height. Treatments for transient elevation of serum prolactin did not affect the sexual behaviour of males, but triggered these significant effects mainly at the ventral prostate. CONCLUSION: The prostate is a sexual gland that responds to prolactin. Mating-induced prolactin release is required during sexual encounters to activate the epithelial cells in the gland. Here we saw a precise mechanism controlling the release of prolactin during ejaculations that avoid the detrimental effects produced by constant levels. However, we showed that minor elevations of prolactin which do not affect the sexual behaviour of males, produced significant changes at the prostate epithelium that could account for triggering the development of hyperplasia or cancer. Thus, it is suggested that minute elevations of serum prolactin in healthy subjects are at the etiology of prostate abnormal growth

Prostate cancer and Hedgehog signalling pathway

[Abstract] The Hedgehog (Hh) family of intercellular signalling proteins have come to be recognised as key mediators in many fundamental processes in embryonic development. Their activities are central to the growth, patterning and morphogenesis of many different regions within the bodies of vertebrates. In some contexts, Hh signals act as morphogens in the dose-dependent induction of distinct cell fates within a target field, in others as mitogens in the regulation of cell proliferation or as inducing factors controlling the form of a developing organ. These diverse functions of Hh proteins raise many intriguing questions about their mode of action. Various studies have now demonstrated the function of Hh signalling in the control of cell proliferation, especially for stem cells and stem-like progenitors. Abnormal activation of the Hh pathway has been demonstrated in a variety of human tumours. Hh pathway activity in these tumours is required for cancer cell proliferation and tumour growth. Recent studies have uncovered the role for Hh signalling in advanced prostate cancer and demonstrated that autocrine signalling by tumour cells is required for proliferation, viability and invasive behaviour. Thus, Hh signalling represents a novel pathway in prostate cancer that offers opportunities for prognostic biomarker development, drug targeting and therapeutic response monitoring

Specific Codon Pairs Inhibit Translation in Yeast and Act by Distinct Mechanisms

Thesis (Ph.D.)--University of Rochester. School of Medicine & Dentistry. Dept. of Biochemistry and Biophysics, 2017.​Translation shapes the proteome and is highly regulated to ensure synthesis of functional proteins. The choice of synonymous codons used to encode a polypeptide modulates translation efficiency and co-translational protein folding, but the identities and properties of codons or codon combinations that impair translation were unknown. In a systematic analysis of the effects of 59/61 sense codons, our lab identified the Arg CGA codon as strongly inhibitory. Furthermore, pairs of CGA codons (CGA-CGA) are stronger inhibitors of translation than single CGA codons. Thus, we reasoned that there could be other pairs of codons that inhibit translation. To identify such inhibitory pairs in the yeast Saccharomyces cerevisiae, we employed a high throughput method to screen a library of over 35,000 GFP variants, in which three adjacent codons were randomized, using fluorescence-activated cell sorting (FACS) and deep-sequencing. We identified 17 codon pairs that substantially reduce GFP expression, showing that the pair, rather than the nucleotide sequence, mRNA structure, or individual codons, is responsible for inhibition. These pairs affect translation since their inhibitory effects are suppressed by tRNA. Specific types of wobble decoding are key to inhibition since an exact base pairing tRNA is a more effective suppressor than a wobble base pairing tRNA. Twelve of the most inhibitory codon pairs are slowly translated in native yeast genes, thus linking slow translation to reduced expression. Moreover, since the order of the codons is critical for inhibition, we infer that an interplay between tRNAs at adjacent sites in the ribosome regulates translation. infer that these codon pairs work by different mechanisms. Inhibition by three pairs, including CGA-CGA, depends upon the ribosomal Asc1 protein and their effects are mediated by the ribosome quality control (RQC) complex. Since inhibition by nine other inhibitory pairs is not dependent upon Asc1, I set up a genetic selection to identify genes that modulate their effects

Transcription antitermination by phage lambda gene Q protein requires a DNA segment spanning the RNA start site.

The gene Q protein of phage lambda is a transcription antiterminator that modifies RNA polymerase near the phage late gene promoter and thereby causes antitermination at distant sites. To define the site of action of Q protein, we have reconstructed the regulatory system on plasmids that allow the intracellular concentration of Q protein to be regulated, and that allow the effect of Q protein on transcription from variant promoter segments to be measured in vivo and in vitro. We show that DNA sequences essential for Q protein-mediated antitermination span the RNA start site, but do not extend beyond nucleotide 18 of the late RNA coding region. We also show that the modification that permits antitermination persists while RNA polymerase passes at least two terminators in vivo and in vitro