Chromatin-binding HMGN proteins and the neuronal differentiation of enbryonal carcinoma cells in vitro

Embryonic stem (ES) cells are able to differentiate in vitro into endodermal, mesodermal and ectodermal cell types. ES cells and their close counterparts, embryonic carcinoma (EC) cells, are a useful model system for studying the mechanisms governing neuronal differentiation. Since High Mobility Group-nucleosome binding (HMGN) genes are regulated in a developmental-stage specific manner during mouse embryogenesis and cellular differentiation, their roles in undifferentiated and neural differentiating P19 EC cells were examined. Work presented in this thesis firstly optimises the Retinoic Acid (RA) -induced neural differentiation protocol of P19 EC cells based on key neuronal and glia markers. Two crucial steps of RA concentration and cell plating density were shown to increase the efficiency of neuronal differentiation. Analysis of HMGN proteins showed they were ubiquitously expressed in undifferentiated and neural differentiating P19 cells. HMGN2 and HMGN3 were up-regulated while HMGN1 remained unchanged upon neural commitment. Unusually, HMGN3 protein was localised in the cytoplasm of P19 cells. To study the possible role of HMGN proteins, HMGN1 and HMGN2 were knocked down using siRNAs. HMGN1 and HMGN2 knockdown in undifferentiated P19 EC cells dramatically down-regulated the key pluripotency regulator genes Oct4, Nanog and Sox2. Furthermore, HMGN1 and HMGN2 knockdown in neural differentiating cells affected seven neuron-specific genes. These data suggest that HMGN proteins may play roles in regulating genes that are involved in maintaining pluripotency and regulating neural differentiation in P19 cells

The Hmgn Family of Chromatin Binding Proteins Regulate Stem Cell Pluripotency and Neuronal Differentiation

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Characterising the HMGN Proteins Expression, and their Role, During Neuronal Differentiation of Mouse P19-ECCs in a Defined Adherent Culture System

No abstract available

Knockdown High Mobility Nucleosomal Binding Proteins 2 (HMGN2) Alter the Histone Modification H4K4me3 and H3K27me3 and Regulates Stem Cells Pluripotency

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Nucleosome-binding HMGN Proteins Inhibit Stem Cell Differentiation Down the Neuronal Lineage

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Maintenance of active chromatin states by HMGN2 is required for stem cell identity in a pluripotent stem cell model

Background: Members of the HMGN protein family modulate chromatin structure and influence epigenetic modifications. HMGN1 and HMGN2 are highly expressed during early development and in the neural stem/progenitor cells of the developing and adult brain. Here, we investigate whether HMGN proteins contribute to the chromatin plasticity and epigenetic regulation that is essential for maintaining pluripotency in stem cells. Results: We show that loss of Hmgn1 or Hmgn2 in pluripotent embryonal carcinoma cells leads to increased levels of spontaneous neuronal differentiation. This is accompanied by the loss of pluripotency markers Nanog and Ssea1, and increased expression of the pro-neural transcription factors Neurog1 and Ascl1. Neural stem cells derived from these Hmgn-knockout lines also show increased spontaneous neuronal differentiation and Neurog1 expression. The loss of HMGN2 leads to a global reduction in H3K9 acetylation, and disrupts the profile of H3K4me3, H3K9ac, H3K27ac and H3K122ac at the Nanog and Oct4 loci. At endodermal/mesodermal genes, Hmgn2-knockout cells show a switch from a bivalent to a repressive chromatin configuration. However, at neuronal lineage genes whose expression is increased, no epigenetic changes are observed and their bivalent states are retained following the loss of HMGN2. Conclusions: We conclude that HMGN1 and HMGN2 maintain the identity of pluripotent embryonal carcinoma cells by optimising the pluripotency transcription factor network and protecting the cells from precocious differentiation. Our evidence suggests that HMGN2 regulates active and bivalent genes by promoting an epigenetic landscape of active histone modifications at promoters and enhancers

The Hmgn Family of Chromatin Binding Proteins Regulate Stem Cell Pluripotency and Neuronal Differentiation

No abstract available

Annona muricata (Annonaceae): A Review of Its Traditional Uses, Isolated Acetogenins and Biological Activities

Annona muricata is a member of the Annonaceae family and is a fruit tree with a long history of traditional use. A. muricata, also known as soursop, graviola and guanabana, is an evergreen plant that is mostly distributed in tropical and subtropical regions of the world. The fruits of A. muricata are extensively used to prepare syrups, candies, beverages, ice creams and shakes. A wide array of ethnomedicinal activities is contributed to different parts of A. muricata, and indigenous communities in Africa and South America extensively use this plant in their folk medicine. Numerous investigations have substantiated these activities, including anticancer, anticonvulsant, anti-arthritic, antiparasitic, antimalarial, hepatoprotective and antidiabetic activities. Phytochemical studies reveal that annonaceous acetogenins are the major constituents of A. muricata. More than 100 annonaceous acetogenins have been isolated from leaves, barks, seeds, roots and fruits of A. muricata. In view of the immense studies on A. muricata, this review strives to unite available information regarding its phytochemistry, traditional uses and biological activities

The Hmgn Family of Chromatin Binding Proteins Regulates Stem Cells Pluripotency and Neuronal Differentiation

No abstract available

Characterising the HMGN Proteins Expression, and their Role, During Neuronal Differentiation of Mouse P19-ECCs in a Defined Adherent Culture System

No abstract available