Maternal and perinatal outcome in eclampsia complicated by posterior reversible encephalopathy syndrome; a three years’ experience in a tertiary care hospital

Background: PRES can be associated with number of medical conditions and was observed frequently in patients with preeclampsia and eclampsia. Neuroimaging is important for the diagnosis of PRES. Study was conducted to find out the maternal and perinatal outcome in patients with eclampsia complicated by posterior reversible encephalopathy syndrome (PRES).Methods: This is a retrospective study done at St. Johns Medical College Bangalore, between October 2013 and October 2016. We reviewed case records of all the patients with eclampsia who underwent neuro imaging studies and a diagnosis of PRES was made. The maternal and perinatal outcomes in these women were studiedResults: In the past three years we had 55 cases of eclampsia who underwent neuroimaging studies for persistent neurological symptoms after 24 hours of MgSO­4 treatment. Of these women 30 were diagnosed to have PRES. In the present study PRES was common in multiparous women and more in patients with antepartum eclamptic women. Mean age at diagnosis of PRES was 26±5.1 years. Common presenting symptoms were headache (93.3%) and vomiting (53.3%). The mean SBP/DBP was 180/110 mmHg. All patients who had recurrent seizures were controlled with MgSO­4 alone. 53.3% of our patients had eclampsia related complications and 36.7% required ICU care. There were 3 maternal deaths (10%). Perinatal mortality was 20%.Conclusions: Neuroimaging in eclamptic patients with persistent neurological symptoms could help in early diagnosis of PRES and multidisciplinary approach in management could contribute significantly in reducing the maternal mortality and morbidity

ATRX Directs Binding of PRC2 to Xist RNA and Polycomb Targets

X chromosome inactivation (XCI) depends on the long noncoding RNA Xist and its recruitment of Polycomb Repressive Complex 2 (PRC2). PRC2 is also targeted to other sites throughout the genome to effect transcriptional repression. Using XCI as a model, we apply an unbiased proteomics approach to isolate Xist and PRC2 regulators and identified ATRX. ATRX unexpectedly functions as a high-affinity RNA-binding protein that directly interacts with RepA/Xist RNA to promote loading of PRC2 in vivo. Without ATRX, PRC2 cannot load onto Xist RNA nor spread in cis along the X chromosome. Moreover, epigenomic profiling reveals that genome-wide targeting of PRC2 depends on ATRX, as loss of ATRX leads to spatial redistribution of PRC2 and derepression of Polycomb responsive genes. Thus, ATRX is a required specificity determinant for PRC2 targeting and function

High-resolution Xist binding maps reveal 2-step spreading during X-inactivation

The Xist long noncoding RNA (lncRNA) is essential for X-chromosome inactivation (XCI), the process by which mammals compensate for unequal numbers of sex chromosomes1-3. During XCI, Xist coats the future inactive X (Xi)4 and recruits Polycomb Repressive Complex 2 (PRC2) to the X-inactivation center (Xic)5. How Xist spreads silencing on a 150 Mb scale is unclear. Here we generate high-resolution maps of Xist binding on the X chromosome across a developmental time course using CHART-seq. In female cells undergoing XCI de novo, Xist follows a two-step mechanism, initially targeting gene-rich islands before spreading to intervening gene-poor domains. Xist is depleted from genes that escape XCI but may concentrate near escapee boundaries. Xist binding is linearly proportional to PRC2 density and H3 lysine 27 trimethylation (H3K27me3), suggesting co-migration of Xist and PRC2. Interestingly, when the Xi is acutely stripped off Xist in post-XCI cells, Xist recovers quickly within both gene-rich and -poor domains on a time-scale of hours instead of days, suggesting a previously primed Xi chromatin state. We conclude that Xist spreading takes distinct stage-specific forms: During initial establishment, Xist follows a two-step mechanism, but during maintenance, Xist spreads rapidly to both gene-rich and -poor regions

LincRNA-p21 Activates p21 In cis to Promote Polycomb Target Gene Expression and to Enforce the G1/S Checkpoint

The p53-regulated long noncoding RNA lincRNA-p21 has been proposed to act in trans via several mechanisms ranging from repressing genes in the p53 transcriptional network to regulating mRNA translation and protein stability. To further examine lincRNA-p21 function, we generated a conditional knockout mouse model. We find that lincRNA-p21 predominantly functions in cis to activate expression of its neighboring gene, p21. Mechanistically, we show that lincRNA-p21 acts in concert with hnRNP-K as a coactivator for p53-dependent p21 transcription. Additional phenotypes of lincRNA-p21 deficiency could be attributed to diminished p21 levels, including deregulated expression and altered chromatin state of some Polycomb target genes, a defective G1/S checkpoint, increased proliferation rates, and enhanced reprogramming efficiency. These findings indicate that lincRNA-p21 affects global gene expression and influences the p53 tumor suppressor pathway by acting in cis as a locus-restricted coactivator for p53-mediated p21 expression.National Institutes of Health (U.S.)Howard Hughes Medical InstituteLudwig Center for Molecular OncologyDamon Runyon Cancer Research Foundatio

Tips in analyzing antibodies directed against specific histone tail modifications.

Publisher Summary This chapter presents several parameters to be taken into consideration and some useful hints for systematic characterization of antibodies raised against methylated histone peptides. It focuses on antibodies against methylated residues—namely, H3-K4, H3-K27, and H4-K20, the methods and procedures described in the chapter are applicable for any antibody directed against the histone tail modifications, including arginine methylation and lysine acetylation, among other modifications. Enzyme-linked immunosorbent assay (ELISA) is the traditional method for antibody characterization. It is the most quantitative and sensitive and the optimal concentration of the antibody. The ELISA should be followed by dot blot analyses. If monoclonal antibodies are to be screened, it is easier to perform dot blot analysis first to isolate specific clones and then proceed to ELISA to ascertain optimal concentrations for the antibody. The antibodies have to be characterized by as many methods as possible and with as many controls as possible. The number of parameters that affect the specificity of the antibody are too many and any result that is derived from chromatin immunoprecipitation (ChIP) and IF experiments must be interpreted with extreme caution

PR-Set7-dependent methylation of histone H4 Lys 20 functions in repression of gene expression and is essential for mitosis

The histone methyl transferase PR-Set7 mediates histone H4 Lys 20 methylation, a mark of constitutive and facultative heterochromatin. We isolated a null mutation in Drosophila PR-Set7 that suppresses position effect variegation, indicating that PR-Set7 indeed functions in silencing general gene expression. In PR-Set7 larval leg and eye discs, the number of cells is lower than normal, and the DNA content in these cells is significantly increased. These data show that PR-Set7-dependent methylation is essential for the process of mitosis. The methylation mark is highly stable and is maintained even in the absence of PR-Set7 protein

Ezh2 Requires PHF1 To Efficiently Catalyze H3 Lysine 27 Trimethylation In Vivo▿

The mammalian Polycomblike protein PHF1 was previously shown to interact with the Polycomb group (PcG) protein Ezh2, a histone methyltransferase whose activity is pivotal in sustaining gene repression during development and in adulthood. As Ezh2 is active only when part of the Polycomb Repressive Complexes (PRC2-PRC4), we examined the functional role of its interaction with PHF1. Chromatin immunoprecipitation experiments revealed that PHF1 resides along with Ezh2 at Ezh2-regulated genes such as the HoxA loci and the non-Hox MYT1 and WNT1 genes. Knockdown of PHF1 or of Ezh2 led to up-regulated HoxA gene expression. Interestingly, depletion of PHF1 did correlate with reduced occupancy of Bmi-1, a PRC1 component. As expected, knockdown of Ezh2 led to reduced levels of its catalytic products H3K27me2/H3K27me3. However, reduced levels of PHF1 also led to decreased global levels of H3K27me3. Notably, the levels of H3K27me3 decreased while those of H3K27me2 increased at the up-regulated HoxA loci tested. Consistent with this, the addition of PHF1 specifically stimulated the ability of Ezh2 to catalyze H3K27me3 but not H3K27me1/H3K27me2 in vitro. We conclude that PHF1 modulates the activity of Ezh2 in favor of the repressive H3K27me3 mark. Thus, we propose that PHF1 is a determinant in PcG-mediated gene repression