Month: January 2020

The anterior pituitary is a gland with considerable plasticity, alterations in the mechanisms that physiologically regulate anterior pituitary cell turnover can be involved in the pathogenesis of pituitary tumors. Since all endocrine pituitary cells, including lactotropes, express prolactin receptors, PRL is assumed to participate in the regulation of anterior pituitary functions including tissue homeostasis. Hence, alterations of PRLR signaling may play a role in anterior pituitary tumor development. According to the effects described for PRL in the majority of its target tissues, it was initially proposed that this hormone may exert trophic action on anterior pituitary cells. However, studies using PRLR knockout mice subsequently showed that PRL actually exerts an opposite effect on lactotropes, since these mice develop pituitary adenomas. Using a specific PRLR antagonist able to partially block PRLR signaling in biological systems where both the ligand and the receptor are expressed, we recently demonstrated that unlike what happens in most other tissues, PRL induced apoptosis and reduced proliferation of anterior pituitary cells from male rats, acting through an autocrine/paracrine mechanism. In females, however, regulation of pituitary homeostasis is a more complex process that remains uncharacterized. The anterior pituitary gland of female rodents undergoes constant remodeling during each estrous cycle. Furthermore, under specific conditions such as pregnancy and lactation, it also responds to particular physiological demands. Anterior pituitary cell turnover is about 3% per day in female rats. During each estrous cycle, a peak of proliferation occurs specifically at estrus whereas the highest rate of apoptosis is observed at proestrus. This cell turnover is a tightly regulated process in which several factors, e.g. estradiol, dopamine, and 16 kDa PRL, were demonstrated to participate. Interestingly, during the afternoon of proestrus, i.e. when the rate of apoptosis is the highest, there is a concomitant peak of serum PRL in response to high circulating levels of estrogens. We hypothesize that the proestrus surge of PRL release participates in anterior pituitary cell renewal that occurs during the estrous cycle. The PRLR is expressed as different isoforms generated by alternative splicing. They include one long and one short isoform in rats and one long and three short isoforms in mice. The long and short isoforms differ in the polypeptide chain of the intracellular domain; hence, they are all able to bind PRL equally but exhibit different abilities to trigger the canonical PRLR intracellular signaling pathways. Although PRLR isoforms are usually co–expressed in the same tissue, one of the isoforms often predominates over the others, depending on the tissue and the physiological context. For example, in the mouse ovary, PRLRlong is the most abundantly expressed isoform, followed by S2 and S3 PRLRshort isoforms.

For example, China has launched national programs for soil testing and fertilizer recommendations since 2005. In 2009, 2,500 counties in China were involved in the programs, receiving a total of 1.5 billion yuan from the Chinese central government. Although the on-farm trials were conducted by local farmers in the same counties as the farmers’ surveys, the management and environment is not always the same for on-farm trials and farmers’ surveys. While gains in grain yield and GHG were achieved by farmers using the trials, we believe that the majority of these gains can be realized in practice in many counties if improved agronomic and N management techniques are adopted. The management and environment differed among four maize regions; thus, N losses may also differ. For example, the annual direct N2O emission accounted for 0.92% of the applied N with an uncertainty of 29%. The highest N2O fluxes occurred in East China as compared with the lowest fluxes in West China. In this study, we use the different exponential relationships of the N application rate and N2O fluxes for spring maize and summer maize, respectively. However, developing N loss models at the regional or subregional scale is difficult due to insufficient field measurement data in China. Longterm field observations covering all subregions are required to accurately assess farming potential and mitigate GHG emissions. In yeast, the NLE1 ortholog Rsa4 is essential for ribosome biogenesis. It assembles in the nucleolus with the pre-60S ribosomal subunit and interacts through its well-conserved amino-terminal region with the AAA-ATPase Rea1. This interaction is required for the disassembly of non-ribosomal factors prior to export of the mature large subunit to the cytoplasm. We recently showed that the key role of NLE1 in 60S biogenesis is conserved during evolution. Using conditional inactivation in adult mice, we demonstrated that NLE1 regulated ribosome biogenesis in hematopoietic stem cells and immature progenitors and was required for the maintenance of these populations. Strikingly, NLE1 was dispensable for ribosome biogenesis, proliferation and differentiation of B lymphocytes, suggesting that alternative pathways for 60S subunit production might exist and be differentially active depending on cell type or degree of differentiation. Limited data is available so far concerning the role of NLE1 during embryonic development. We previously reported that constitutive Nle1 inactivation leads to embryonic lethality around the time of implantation due to selective apoptosis of pluripotent cells of the blastocyst. Early embryonic lethality has recently been reported for mice homozygous for non-conservative missense Nle1 mutations obtained by ENU mutagenesis. The skin being the largest organ in our body, accounts for about 16% of the net body weight and serves as a barrier against various biological, mechanical, chemical and thermal injuries.

DMD exon skipping trial using a 2OMeAO was halted as primary and secondary endpoints were not met. While disappointing for the DMD community, these trial results cannot be regarded as surprising as there had been no unequivocal increases in dystrophin after 2OMe AO treatment. In contrast, another DMD exon skipping trial using an oligomer composed of the PMO chemistry appears to have stabilized ambulation in 10 out or 12 trial participants, with robust dystrophin being detected in muscle biopsies from these boys. A previous study by Fong and colleagues employed another splice switching oligonucleotide chemistry, 29-methoxy-ethyl modified bases on a phosphorothioate backbone to activate the cryptic splice site in normal human fibroblasts. Their most effective AO targeted 34 to 56 bases downstream of the HGPS cryptic splice site, whereas in this study two other domains downstream to the cryptic splice site were most efficient in inducing progerin. Another difference between this study and that by Fong et al, is that our study identified a wider area that can mediate progerin expression. Further, whereas a seemingly precise switching from lamin A to progerin production was achieved by Fong et al, variable degrees of exon 11 skipping invariably accompanied increased utilization of the cryptic site in our study with 2OMe AOs. For example, the 2OMe AO 11A has the same sequence as one of the most efficient AOs described by Fong et al., and caused both cryptic splice site activation and exon 11 skipping in our study. Several factors may contribute to the discrepancies between the two studies, including the use of different cell strains and different AO chemistries. However, we also transfected normal human skin fibroblasts with our AOs and the resulting splicing pattern was identical to that induced in myogenic cells. It is therefore unlikely that splicing environment in different tissues is responsible for the disparity in splicing redirection in the different studies. The variable efficiencies with which progerin was induced by our 2OMe AOs and PMOs also support the possibility that the oligonucleotide chemistry has a major impact on transfection outcomes. But other factors may also contribute: different AO length, transfection concentrations and PCR amplification conditions. We could induce the accumulation of progerin as well as lamin A DE11 in human myogenic cells using splicing switching AOs. Both progerin and lamin A DE11 lack a proteolytic site for posttranslational modification of the precursor protein prelamin A. Consequently, both aberrant proteins retain a farnesyl group at the C terminal, which is normally cleaved from the wild-type mature lamin A. It is proposed that the farnesyl group plays a key role in the pathogenesis of farnesylated prelamin A-accumulating diseases. The retention of the farnesyl group prevents the progerin from disassociating from the nuclear lamina during the cell cycle and disrupts mitosis.

Consequently it is not possible to ascertain whether or not a transporter redistribution was taking place when observing no decrease in radioligand binding in crude membrane preparations. We demonstrate that mephedrone, administered at doses that mimic a high exposure in humans, induced an important decrease in DA transporter density in mouse striatum and frontal cortex membranes that persisted 7 days after exposition. This effect was accompanied by a significant loss of 5-HT transporters in the hippocampus. However, at these high doses, acute cardiovascular toxicity of mephedrone is likely and probably outweighs neurotoxic effects. The subsequent experiments were carried out at a lower dose. Schedule 2 dosage schedule only elicited a transient decrease in cortical DA transporter, suggesting a temporary regulatory effect. Moreover, no significant loss of 5-HT transporter in the frontal cortex or the hippocampus was found. Schedule 3 can be considered the most representative because it is closest to the typical weekend consumption pattern. After this exposure, mephedrone induced loss of DA and 5-HT transporters that were especially apparent in the frontal cortex and the hippocampus respectively. The monoamine deficit induced by this schedule was also characterized by a significant decrease of each enzymatic marker that correlated with the decrease in radioligand binding. TH and TPH catalyze the first and rate-limiting step in the biosynthesis of DA and 5-HT respectively. The isoform TPH2 is responsible for 5-HT biosynthesis in the brain. Post-translational modifications have been shown to regulate the protein function. The enzyme is known to be phosphorylated on Ser-19 by both protein kinase A and calmodulin dependent protein kinase II in vitro. This modification results in increased stability and activity. The decrease in transporter binding and enzyme levels, jointly with astrogliosis, point to an injury at the nerve endings; the increase in Ser-19TPH2 in mephedrone-treated animals seems to reflect a compensatory mechanism in the undamaged 5-HT terminals The recovery of DA transporter levels in mouse striatum after 7 days of exposition raises the question on whether the decrease in WIN35428 binding observed 3 days after exposition is an effect of biochemical down-regulation in the absence of tissue damage rather than being reflective of an injury. The nonsignificant increase in astroglial activation observed in this area was consistent with the absence of terminal injury and suggests that the DA transporter gene expression may be negatively regulated by mephedrone exposure. This is consistent with previous results reporting that MDMA acts on 5-HT transporter gene expressions. Moreover, although DA transporter density returns to basal values in crude membrane preparations 7 days after exposition, results point to changes in DA levels in the striatal synapses, seeing as there is a significant redistribution of this transporter.

Associated changes in the concentration and bioactivity of exosomes present in maternal peripheral plasma. The data obtained in this study establish, that pregnancy is associated with a 50-fold increase in the concentration of exosomes in maternal plasma. In a longitudinal study, the concentration of placental exosomes in plasma increased during pregnancy and correlated with mean uterine artery blood flow. At delivery, plasma concentration of placental exosomes correlated with placental weight. The study further established that exosomes present in maternal plasma are bioactive and promote cell migration. These data clearly establish that normal healthy pregnancy is characterised by the release of bioactive exosomes into maternal blood from as early as 6 weeks of gestation and that the concentration of placenta-specific exosomes is information of placental perfusion and growth. This study provides proof-ofprinciple and baseline data that may facilitate the early identification of dysfunctional placentation. In this study, exosomes were isolated using differential and buoyant density centrifugation to obtain enriched exosome population. Nanovesicles isolated using this method, displayed a diameter between,40-120 a buoyant density on sucrose gradient of 1.21–1.192 g/m and were positive for the exosome markers, CD63, CD9 and CD81. These data are characteristic of exosomes and consistent with previously published data. The data obtained in this study establish that pregnancy is associated with a dramatic increase in the number of exosomes circulating in maternal blood. The concentration of exosomal protein in first trimester plasma was 50-fold greater than that observed in non-pregnant women. Maternal plasma exosomal protein concentrations increased a further two-fold during pregnancy, to be 100-fold greater than non-pregnant values. Exosomes present in maternal plasma may be derived from either maternal and/or fetal origin. To address this question, plasma exosomes were further characterised by the presence of a syncytiotrophoblast-specific marker. PLAP was not detectable in the exosomal fraction from non-pregnant plasma and is consistent with previously published data. Plasma exosomal PLAP displayed a similar gestational age profile to that observed for exosome number and was significantly correlated with exosomal protein and CD63 at delivery. The syncytiotrophblast is in direct contact with maternal blood and, with a surface area of. 10 m2, it represents a significant source of placenta vesicular membrane entering maternal blood. More that 3 g of syncytiotrophblast-derived membrane is released each day near term. The contribution of syncytiotrophblastderived exosomes to total syncytiotrophblast membrane released, however, is not known. Similarly, no quantitative estimates of the contribution of syncytiotrophblast-derived exosomes to total maternal plasma exosomes remains to be established.