Double-stranded RNA-stimulated enzyme activities isolated from human placental extracts

A (2′–5′)A_n synthetase activity was isolated from human placental extracts by affinity chromatography on poly(rI)·poly(rC)-agarose. The oligonucleotide (2′–5′)A_n was identified by (1) chromatography on PEI-cellulose and DEAE-cellulose, (2) inhibition of polypeptide synthesis in lysed rabbit reticulocytes (3) competition of the binding of pppA(pA)3,3′-[³²P]pCp to rabbit reticulocyte lysates, and (4) alkaline phosphatase digestion. The synthetase activity in most placental preparations is activated by natural or synthetic dsRNA. However, in a few placental synthetase preparations, dsRNA is only marginally stimulatory and only becomes effective by prior treatment of the enzyme preparations with the calcium-dependent micrococal nuclease. This suggeststhat there is an endogenous placental dsRNA contaminant in the enzyme preparations. In some synthetase preparations, a second dsRNA-stimulated product, tentatively identified as the nucleotide 5′-IMP, is also observed. Because the specific AMP deaminase inhibitor coformycin (10 μM) blocks the formation of IMP from ATP and causes a quantitative accumulation of AMP, and because the formation of IMp becomes independent of dsRNA when ADP or AMP is used in plase of ATP, the presence of a dsRNA-stimulated ATP phosphohydrolase (ATPase) activity in human placenta is suggested.     

Isolation of Cellular Lipid Droplets: Two Purification Techniques Starting from Yeast Cells and Human Placentas

Lipid droplets are dynamic organelles that can be found in most eukaryotic and certain prokaryotic cells. Structurally, the droplets consist of a core of neutral lipids surrounded by a phospholipid monolayer. One of the most useful techniques in determining the cellular roles of droplets has been proteomic identification of bound proteins, which can be isolated along with the droplets. Here, two methods are described to isolate lipid droplets and their bound proteins from two wide-ranging eukaryotes: fission yeast and human placental villous cells. Although both techniques have differences, the main method - density gradient centrifugation - is shared by both preparations. This shows the wide applicability of the presented droplet isolation techniques.In the first protocol, yeast cells are converted into spheroplasts by enzymatic digestion of their cell walls. The resulting spheroplasts are then gently lysed in a loose-fitting homogenizer. Ficoll is added to the lysate to provide a density gradient, and the mixture is centrifuged three times. After the first spin, the lipid droplets are localized to the white-colored floating layer of the centrifuge tubes along with the endoplasmic reticulum (ER), the plasma membrane, and vacuoles. Two subsequent spins are used to remove these other three organelles. The result is a layer that has only droplets and bound proteins.In the second protocol, placental villous cells are isolated from human term placentas by enzymatic digestion with trypsin and DNase I. The cells are homogenized in a loose-fitting homogenizer. Low-speed and medium-speed centrifugation steps are used to remove unbroken cells, cellular debris, nuclei, and mitochondria. Sucrose is added to the homogenate to provide a density gradient and the mixture is centrifuged to separate the lipid droplets from the other cellular fractions.The purity of the lipid droplets in both protocols is confirmed by Western Blot analysis. The droplet fractions from both preps are suitable for subsequent proteomic and lipidomic analysis.     

Expression of imprinted genes in placenta is associated with infant neurobehavioral development

Genomic imprinting disorders often exhibit delayed neurobehavioral development, suggesting this unique mechanism of epigenetic regulation plays a role in mental and neurological health. While major errors in imprinting have been linked to adverse health outcomes, there has been little research conducted on how moderate variability in imprinted gene expression within a population contributes to differences in neurobehavioral outcomes, particularly at birth. Here, we profiled the expression of 108 known and putative imprinted genes in human placenta samples from 615 infants assessed by the Neonatal Intensive Care Unit (NICU) Network Neurobehavioral Scales (NNNS). Data reduction identified 10 genes (DLX5, DHCR24, VTRNA2-1, PHLDA2, NPAP1, FAM50B, GNAS-AS1, PAX8-AS1, SHANK2, and COPG2IT1) whose expression could distinguish between newborn neurobehavioral profiles derived from the NNNS. Clustering infants based on the expression pattern of these genes identified 2 groups of infants characterized by reduced quality of movement, increased signs of asymmetrical and non-optimal reflexes, and increased odds of demonstrating increased signs of physiologic stress and abstinence. Overall, these results suggest that common variation in placental imprinted gene expression is linked to suboptimal performance on scales of neurological functioning as well as with increased signs of physiologic stress, highlighting the central importance of the control of expression of these genes in the placenta for neurobehavioral development.     

Protein tyrosine phosphatase interacting protein 51 (PTPIP51) mRNA expression and localization and its in vitro interacting partner protein tyrosine phosphatase 1B (PTP1B) in human placenta of the first, second, and third trimester

The cellular localization of protein tyrosine phosphatase 51 (PTPIP51) and its in vitro interacting partner protein tyrosine phosphatase 1B (PTP1B) was studied in human placentae of different gestational stages. The expression of PTPIP51 protein and mRNA was observed in the syncytiotrophoblast and cytotrophoblast layer of placentae from the first, second, and third trimesters. In contrast, PTP1B expression was restricted to the syncytiotrophoblast during all gestational stages. Cells of the cytotrophoblasts and parts of the syncytiotrophoblasts expressing high amounts of PTPIP51 were found to execute apoptosis as shown by TdT-mediated dUTP-biotin nick end labeling assay, cytokeratin 18f, and caspase 3 expression. PTPIP51 could also be traced in the endothelium and smooth muscle cells of placental arterial and venous vessels, identified by double immunostainings with antibodies directed against van Willebrand factor and alpha-smooth muscle actin. Some of these cells showing a high PTPIP51 reactivity were Ki67 positive, indicating proliferation. Additionally, a small population of placental CD14-positive macrophages and mesenchymal cells within the villous stroma were detected as PTPIP51 positive. Our data suggest that both proteins, PTPIP51 and PTP1B, play a role in differentiation and apoptosis of the cytotrophoblast and syncytiotrophoblast, respectively. Moreover, PTPIP51 may also serve as a cellular signaling partner in angiogenesis and vascular remodeling.     

Placental enzymes involved in regulatory peptide metabolism in EPH-gestosis

Essential edema-proteinuria-hypertension (EPH) gestosis still represents an important obstetrical problem. We have investigated the activity of carboxypeptidase H (CPH), phenylmethylsulfonyl fluoride inhibited carboxypeptidase (PMSF-CP), carboxypeptidase M (CPM) and angiotensin-converting enzyme (ACE), the main carboxypeptidases in human placenta under normal conditions and mild EPH-gestosis. Gestosis was accompanied by the decrease in activity of the enzymes involved into metabolism of regulatory peptides (ACE, CPH, PMSF-CP, CPM) compared with their activity in placenta under physiological pregnancy. Correlation analysis revealed positive correlation between placental CPH and CPM (r = 0.2735*) in EPH-gestosis. These findings suggest involvement of placental proteases into formation of compensatory-adaptive reactions in the fetoplacental complex at EPH-gestosis; the data obtained may be also employed for the development of methods of prophylaxis and corrections of metabolic impairments in pathology of pregnancy.     

Is a foetus developing in a sterile environment?

Novel findings in microbiology question the long‐standing paradigm that a healthy pregnancy implies a sterile uterus. It now seems that the placenta is frequently colonized with bacteria, and a placental microbiome has been identified. Recent literature findings are summarized here, and an attempt is made to separate pathological bacterial presence from a naturally occurring microbiome.