Discordance of prolactin gene transcription, mRNA storage, and hormone release in individual mammotropes

Preimplantation factor modulates trophoblastic invasion throughout the decidualization of human endometrial stromal cells

BACKGROUND

Successful human embryo implantation requires the differentiation of endometrial stromal cells (ESCs) into decidual cells during a process called decidualization. ESCs express specific markers of decidualization, including prolactin, insulin-like growth factor-binding protein-1 (IGFBP-1), and connexin-43. Decidual cells also control of trophoblast invasion by secreting various factors, such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases. Preimplantation factor (PIF) is a recently identified, embryo-derived peptide with activities at the fetal-maternal interface. It creates a favorable pro-inflammatory environment in human endometrium and directly controls placental development by increasing the human trophoblastic cells' ability to invade the endometrium. We hypothesized that PIF's effects on the endometrium counteract its pro-invasive effects.

METHODS

We tested sPIF effect on the expression of three decidualization markers by RT-qPCR and/or immunochemiluminescence assay. We examined sPIF effect on human ESC migration by performing an in vitro wound healing assay. We analyzed sPIF effect on endometrial control of human trophoblast invasion by performing a zymography and an invasion assay.

RESULTS

Firstly, we found that a synthetic analog of PIF (sPIF) significantly upregulates the mRNA expression of IGFBP-1 and connexin-43, and prolactin secretion in ESCs - suggesting a pro-differentiation effect. Secondly, we showed that the HTR-8/SVneo trophoblastic cell line's invasive ability was low in the presence of conditioned media from ESCs cultured with sPIF. Thirdly, this PIF's anti-invasive action was associated with a specifically decrease in MMP-9 activity.

CONCLUSION

Taken as a whole, our results suggest that PIF accentuates the decidualization process and the production of endometrial factors that limit trophoblast invasion. By controlling both trophoblast and endometrial cells, PIF therefore appears to be a pivotal player in the human embryo implantation process.

Expression and Localization of Lung Surfactant Proteins in Human Testis

Background

Surfactant proteins (SPs) have been described in various tissues and fluids including tissues of the nasolacrimal apparatus, airways and digestive tract. Human testis have a glandular function as a part of the reproductive and the endocrine system, but no data are available on SPs in human testis and prostate under healthy and pathologic conditions.

Objective

The aim of the study was the detection and characterization of the surfactant proteins A, B, C and D (SP-A, SP-B, SP-C, SP-D) in human testis. Additionally tissue samples affected by testicular cancer were investigated.

Results

Surfactant proteins A, B, C and D were detected using RT-PCR in healthy testis. By means of Western blot analysis, these SPs were detected at the protein level in normal testis, seminoma and seminal fluid, but not in spermatozoa. Expression of SPs was weaker in seminoma compared to normal testicular tissue. SPs were localized in combination with vimentin immunohistochemically in cells of Sertoli and Leydig.

Conclusion

Surfactant proteins seem to be inherent part of the human testis. By means of physicochemical properties the proteins appear to play a role during immunological and rheological process of the testicular tissue. The presence of SP-B and SP-C in cells of Sertoli correlates with their function of fluid secretion and may support transportation of spermatozoa. In seminoma the expression of all SP's was generally weaker compared to normal germ cells. This could lead to a reduction of immunomodulatory and rheology processes in the germ cell tumor.

The expression and regulation of matrix metalloproteinase-3 is critically modulated by Porphyromonas gingivalis lipopolysaccharide with heterogeneous lipid A structures in human gingival fibroblasts

Background

Porphyromonas gingivalis lipopolysaccharide (LPS) is a crucial virulence factor strongly associated with chronic periodontitis which is the primary cause of tooth loss in adults. It exhibits remarkable heterogeneity containing tetra-(LPS_1435/1449) and penta-(LPS₁₆₉₀) acylated lipid A structures. Human gingival fibroblasts (HGFs) as the main resident cells of human gingiva play a key role in regulating matrix metalloproteinases (MMPs) and contribute to periodontal homeostasis. This study investigated the expression and regulation of MMPs1-3 and tissue inhibitors of MMP-1 (TIMP-1) in HGFs in response to P. gingivalis LPS_1435/1449 and LPS₁₆₉₀ and hexa-acylated E. coli LPS as a reference. The expression of MMPs 1–3 and TIMP-1 was evaluated by real-time PCR and ELISA.

Results

The MMP-3 mRNA and protein were highly upregulated in P. gingivalis LPS₁₆₉₀- and E. coli LPS-treated cells, whereas no induction was observed in P. gingivalis LPS_1435/1449-treated cells. On the contrary, the expression of MMP-1 and −2 was not significantly affected by P. gingivalis LPS lipid A heterogeneity. The TIMP-1 mRNA was upregulated in P. gingivalis LPS_1435/1449- and E. coli LPS-treated cells. Next, signal transduction pathways involved in P. gingivalis LPS-induced expression of MMP-3 were examined by blocking assays. Blockage of p38 MAPK and ERK significantly inhibited P. gingivalis LPS₁₆₉₀-induced MMP-3 expression in HGFs.

Conclusion

The present findings suggest that the heterogeneous lipid A structures of P. gingivalis LPS differentially modulate the expression of MMP-3 in HGFs, which may play a role in periodontal pathogenesis.

The prolactin gene: a paradigm of tissue-specific gene regulation with complex temporal transcription dynamics

Transcription of numerous mammalian genes is highly pulsatile, with bursts of expression occurring with variable duration and frequency. The presence of this stochastic or 'noisy' expression pattern has been relatively unexplored in tissue systems. The prolactin gene provides a model of tissue-specific gene regulation resulting in pulsatile transcription dynamics in both cell lines and endocrine tissues. In most cell culture models, prolactin transcription appears to be highly variable between cells, with differences in transcription pulse duration and frequency. This apparently stochastic transcription is constrained by a transcriptional refractory period, which may be related to cycles of chromatin remodelling. We propose that prolactin transcription dynamics result from the summation of oscillatory cellular inputs and by regulation through chromatin remodelling cycles. Observations of transcription dynamics in cells within pituitary tissue show reduced transcriptional heterogeneity and can be grouped into a small number of distinct patterns. Thus, it appears that the tissue environment is able to reduce transcriptional noise to enable coordinated tissue responses to environmental change. We review the current knowledge on the complex tissue-specific regulation of the prolactin gene in pituitary and extra-pituitary sites, highlighting differences between humans and rodent experimental animal models. Within this context, we describe the transcription dynamics of prolactin gene expression and how this may relate to specific processes occurring within the cell.

Multi-transcriptional profiling of melanin-concentrating hormone and orexin-containing neurons

1.Melanin-concentrating hormone (MCH) and orexin-containing neurons participate in hypothalamic circuits that control energy homeostasis. While these two systems have projections to widespread target areas within the central nervous system, little is known about intrinsic characteristics and the molecular composition of both the MCH and orexin neurons themselves. 2. By a combinatory approach of quantitative immunocytochemical identification and analysis with laser microdissection and semi-quantitative Real-time RT-PCR, here we present multi-transcriptional profiling of MCH and orexin neurons in the rat lateral hypothalamus. 3. Immunocytochemical analysis showed that orexin peptide expression was increased after fasting both during the activity and resting period of rats, whereas MCH peptide content was only clearly upregulated at resting phase. Subsequent transcriptional profiling showed distinct expression patterns of MCH, orexin and cocaine-amphetamine regulated transcript (CART) between MCH and orexin neurons. A low expression level of dynorphin was found both in MCH and orexin neurons. Receptor expression profiles, reflecting interaction with neuropeptide Y, melanocortins, leptin, glucocorticoids and GABA, showed approximately similar expression patterns among the MCH and orexin neuronal systems. Expression of glutamate- and GABA-markers revealed a possible contributory role of both glutamate and GABA in functional output of MCH and orexin neurons. 4. This method allowed differential screening at mRNA level after immunocytochemical neuron identification and analysis in heterogeneous brain regions, which can further specify functioning of the individual neurons. With respect to MCH and orexin neurons, this study emphasizes that these neurons are targets for stimulatory and inhibitory signals from other brain regions including the arcuate nucleus and the general circulation. Additionally, both glutamate and GABA appear to be involved in MCH and orexin neuronal functioning related to feeding and regulation of the energy balance.

Rat strain differences in responses of plasma prolactin and PRL mRNA expression after acute amphetamine treatment or restraint stress

1. The aim of this study was to compare the effects of acute amphetamine (AMPH) treatment and restraint stress on plasma level of prolactin (PRL) and PRL mRNA expression in the adenohypophysis in Sprague-Dawley and Lewis male rats, the latter known to have a deficient hypothalamo-pituitary-adrenal (HPA) axis. 2. Both restraint stress and AMPH treatment (i.p. in a dose of 8 mg/kg of b.w.) were applied 15 or 30 min before termination of the experiment. Plasma PRL and corticosterone (CORT) were determined by radioimmunoassay. PRL mRNA expression was estimated by a dot-blot hybridization. 3. Restraint stress and AMPH treatment induced a significant increase in the CORT plasma level, as an indicator of stress response. Compared to Sprague-Dawley rats, the magnitude of CORT increase after both stimuli was significantly lower in Lewis rats. 4. Although restraint stress significantly increased the PRL plasma levels in both rat strains, AMPH treatment reduced the PRL levels in both rat strains. However, the changes of PRL plasma levels had another pattern in Lewis rats than in Sprague-Dawley rats. Control plasma PRL levels were significantly higher in Lewis rats, and in this rat strain AMPH treatment for 30 min increased the PRL levels as compared to the values obtained after AMPH treatment for 15 min. 5. Expression of PRL mRNA in adenohypophysis by restraint stress and AMPH treatment had a similar pattern. After a 15-min lasting restraint stress, the expression of PRL mRNA was decreased insignificantly in both rat strains. AMPH treatment induced in Sprague-Dawley rats a significant decrease of PRL mRNA after a 15-min interval while after 30 min there was a significant increase. However, in Lewis rats AMPH failed to significantly change PRL mRNA. 6. The results from the present study indicate that the mechanisms mediating the effects of acute restraint stress and acute AMPH treatment differ in PRL response in Sprague-Dawley and Lewis male rat strains. Differences in the observed responses in Lewis rats could be related to the deficient activity of HPA axis in this rat strain.

Prolactin: structure, function, and regulation of secretion

Prolactin is a protein hormone of the anterior pituitary gland that was originally named for its ability to promote lactation in response to the suckling stimulus of hungry young mammals. We now know that prolactin is not as simple as originally described. Indeed, chemically, prolactin appears in a multiplicity of posttranslational forms ranging from size variants to chemical modifications such as phosphorylation or glycosylation. It is not only synthesized in the pituitary gland, as originally described, but also within the central nervous system, the immune system, the uterus and its associated tissues of conception, and even the mammary gland itself. Moreover, its biological actions are not limited solely to reproduction because it has been shown to control a variety of behaviors and even play a role in homeostasis. Prolactin-releasing stimuli not only include the nursing stimulus, but light, audition, olfaction, and stress can serve a stimulatory role. Finally, although it is well known that dopamine of hypothalamic origin provides inhibitory control over the secretion of prolactin, other factors within the brain, pituitary gland, and peripheral organs have been shown to inhibit or stimulate prolactin secretion as well. It is the purpose of this review to provide a comprehensive survey of our current understanding of prolactin's function and its regulation and to expose some of the controversies still existing.

Differential influences of gender and physiological status on calcium dynamics and prolactin gene expression in rat mammotropes

The rate of prolactin (PRL) secretion is influenced by the gender and physiological state of an animal, but little is known about the mechanisms involved. In the present study, we assessed possible contributions of Ca2+ dynamics and PRL gene expression to these differences. This was accomplished by monitoring spontaneous [Ca2+]i changes and PRL promotor-driven reporter activity in pituitary cultures derived from rats comprising a broad spectrum of PRL secretory capacities: male, cycling female, and lactating rats. We found that Ca2+ oscillatory activity exhibited a rank order of lactating > cycling females > males, consistent with the reported secretory capacities of mammotropes from these sources. Interestingly, we observed that the basal level of PRL promotor-driven reporter activity was the same for all three models, but that mammotropes from males were the most responsive to stimulation of PRL gene expression by elevation of [Ca2+]i. Collectively, our findings reveal gender- and state-specific differences in Ca2+ dynamics and induction of PRL gene expression. These likely contribute to reported differences in secretory capacity.