Histone citrullination represses miRNA expression resulting in increased oncogene mRNAs in somatolactotrope cells.

Peptidylarginine deiminase (PAD) enzymes convert histone arginine residues into citrulline to modulate chromatin organization and gene expression. Although PADs are expressed in anterior pituitary gland cells, their functional role and expression in pituitary adenomas is unknown. To begin to address these questions, we first examined normal human pituitaries and pituitary adenomas and found that PAD2, PAD4 and citrullinated histones are highest in prolactinomas and somatoprolactinomas. In the somatoprolactinoma-derived GH3 cell line, PADs citrullinate histone H3, which is attenuated by a pan-PAD inhibitor. RNA-sequencing and ChIP studies show that the expression of microRNAs let-7c-2, miR-23b and miR-29c is suppressed by histone citrullination. Our studies demonstrate that these miRNAs directly target the mRNA of the oncogenes HMGA, IGF-1 and N-MYC, which are highly implicated in human prolactinoma/somatoprolactinoma pathogenesis. Our results are the first to define a direct role for PAD catalyzed histone citrullination in miRNA expression, which may underlie the etiology of prolactinoma and somatoprolactinoma tumors through regulation of oncogene expression

Progesterone stimulates histone citrullination to increase IGFBP1 expression in uterine cells

Peptidylarginine deiminases (PAD) enzymes were initially characterized in uteri, but since then little research has examined their function in this tissue. PADs post-translationally convert arginine residues in target proteins to citrulline and are highly expressed in ovine caruncle epithelia and ovine uterine luminal epithelial (OLE)-derived cell line. Progesterone (P4) not only maintains the uterine epithelia but also regulates the expression of endometrial genes that code for proteins that comprise the histotroph and are critical during early pregnancy. Given this, we tested whether P4 stimulates PAD-catalyzed histone citrullination to epigenetically regulate expression of the histotroph gene insulin-like growth factor binding protein 1 (IGFBP1) in OLE cells. 100 nM P4 significantly increases IGFBP1 mRNA expression; however, this increase is attenuated by pre-treating OLE cells with 100 nM progesterone receptor antagonist RU486 or 2 microM of a pan-PAD inhibitor. P4 treatment of OLE cells also stimulates citrullination of histone H3 arginine residues 2, 8, and 17 leading to enrichment of the ovine IGFBP1 gene promoter. Since PAD2 nuclear translocation and catalytic activity require calcium, we next investigated whether P4 triggers calcium influx in OLE cells. OLE cells were pre-treated with 10 nM nicardipine, an L-type calcium channel blocker, followed by stimulation with P4. Using fura2-AM imaging, we found that P4 initiates a rapid calcium influx through L-type calcium channels in OLE cells. Furthermore, this influx is necessary for PAD2 nuclear translocation and resulting citrullination of histone H3 arginine residues 2, 8, and 17. Our work suggests that P4 stimulates rapid calcium influx through L-type calcium channels initiating PAD-catalyzed histone citrullination and an increase in IGFBP1 expression

Influence of absorption promoters on pulmonary insulin bioactivity

The purpose of this research was to enhance the bioactivity of insulin by the pulmonary route using a combination of absorption promoters. Aliquots (100 μL) containing 1.0 IU/kg to 7.0 IU/kg doses of porcine insulin solutions with different classes of absorption promoters and combinations of these at 3 concentration levels were instilled intratracheally to the anesthetized rats. Blood concentrations of glucose were measured at specific time points. Out of 3 concentration levels of each of the absorption promoters used, the formulations having the leastconcentration with the maximum percentage of blood glucose reduction were selected for combining absorption promoters, and their pharmacodynamic parameters related to insulin absorption were determined. The pharmacodynamics of porcine insulin following subcutaneous administration of increasing doses were also determined. The relative pulmonary bioactivity of insulin in phosphate buffer pH 7.4 and citrate buffer pH 3.5 was 11.36%±1.27% and 43.20% ±2.48%, respectively, compared to subcutaneous administration. Relative pulmonary bioactivity of 155.60%±5.19% was obtained when oleic acid sodium salt, sodium tauroglycocholate, bestatin, and chymostatin were coadministered in citrate buffer pH 3.5 solution. However, only 61.91%±3.21, 67.09%±3.23%, 67.24%±2.11%, and 69.84%±3.02% were obtained, respectively, upon incorporation of these absorption promoters individually. Absorption promoters in combination have significant potential for increasing the pulmonary bioactivity of insulin. These studies support the argument that pulmonary administration of insulin is a viable alternative to subcutaneous administration for diabetic patients

Palynoflora of the late Paleocene silicified shale at Almont, North Dakota, USA

A pollen and spore assemblage of 50 species was recovered from the late Paleocene (pollen zone P5) Almont locality in the Williston Basin, central North Dakota, USA. This palynoflora was extracted from the same layer containing a diverse megaflora preserved in a silicified shale with compressed leaves, and anatomically preserved fruits and seeds. More than 44 megafossil genera assignable to 26 extant plant families thus far have been recognized. The palynomorphs, which are of exceptional preservation, were examined using the same-grain technique with both light microscopy (LM) and scanning electron microscopy (SEM). Additional LM and SEM studies augmented the same grain studies to provide an understanding of sculptural features, and additional, rare taxa. Of particular note are the in situ pollen types known from catkins and pollen cones, allowing for confirmation of the dispersed pollen\u27s systematic position by tying it to its parent plant. Taxa for which in situ pollen is known from Almont include taxodiaceous conifers, Betulaceae, Hamamelidaceae, Juglandaceae, and Platanaceae, and several catkins of uncertain affinities, some with monosulcate grains. This study emphasizes the role of palynology in providing an expanded view of the flora from palynomorphs for comparison with a rich megafossil assemblage

Alirocumab and cardiovascular outcomes after acute coronary syndrome

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