Maintenance of neuronal identity and function

Neurons in the CNS acquire specific characteristics throughout development and maintain them for the entire lifespan. Instructive regulation of the transcription machinery ensures the acquisition of identity by spatiotemporal patterns of transcription factor expression. Additionally, gene silencing of alternative lineages is important for specification of neuronal identity and function, however the mechanisms regulating transcriptional repression are poorly understood. In this study we focused on epigenetic regulation of gene expression and how perturbation of it can lead to loss of function and disease. In Paper I we characterized histone modifications on two clinically relevant neuronal populations, the dopaminergic and serotonergic neurons implicated in Parkinson’s disease and depression respectively. We studied the repressive modifications H3K27me3, H3K9me3 and active H3K4me3 and associated them with gene expression levels throughout cell maturation, from NPCs to adult postmitotic neurons. The generated comprehensive map also illustrates how drug induced stress in dopaminergic neurons alters the histone modifications pattern affecting gene expression. After acquisition of identity, Paper II focuses on how this can be maintained throughout life. Removal of H3K27me3 in dopaminergic and serotonergic neurons resulted to erroneous gene expression patterns and progressive loss of neuronal function. In dopaminergic neurons electrophysiological and molecular properties were perturbed in a region specific manner, with SNc being the most vulnerable, phenomenon similar to PD development. Mice showed phenotypic impairments with motor symptoms or anxiety-like behavior in cell-type dependent manner. In Paper III DNA methylation in neuroblastoma tumors was examined as a potential therapeutic approach. Hypermethylated loci keep potential tumor suppressors silenced leading to cancer formation. Here we showed that combined administration of the demethylating AZA with RA that promotes neuronal differentiation exhibited a favorable outcome in tumor growth. Further analysis of treated xenografted tumors revealed EPAS1 as a potential tumor suppressor, opposite to previously published data assigning the gene as an oncogene

Bisphosphonate’s effect in hepatic rat cells: An electron microscopy study

Σκοπός: Τα διφωσφονικά αποτελούν εκλεκτικούς αναστολείς της οστικής απορρόφησης και η μακροχρόνια χρήση τους έχει συσχετισθεί με ανεπιθύμητες επιδράσεις στο γαστρεντερικό σύστημα. Σκοπός της εργασίας είναι η διερεύνηση των πιθανών επιδράσεων των διφωσφονικών στη δομή των ηπατικών κυττάρων. Υλικά και μέθοδος: Ελήφθησαν δείγματα ηπατικού ιστού από δέκα θηλυκά ποντίκια Wistar ηλικίας δώδεκα μηνών που έλαβαν Αλενδρονάτη από του στόματος για 13 εβδομάδες και από δέκα θηλυκά ποντίκια Wistar ηλικίας δώδεκα μηνών που δεν έλαβαν το φάρμακο και χρησιμοποιήθηκαν ως μάρτυρες. Τα δείγματα μελετήθηκαν με το ηλεκτρονικό μικροσκόπιο. Αποτελέσματα: Στα ηπατικά κύτταρα των ποντικιών που έλαβαν Αλενδρονάτη βρέθηκαν εκτεταμένη απώλεια γλυκογόνου, διαφόρου μεγέθους κενοτόπια, διευρυμένα κολπώδη τριχοειδή, καθώς και απουσία των μικρολαχνών σε πολλά σημεία του χώρου του Disse. Συμπέρασμα: Πρόκειται για την πρώτη μελέτη με ηλεκτρονικό μικροσκόπιο ηπατικών δειγμάτων μετά τη χορήγηση διφωσφονικών, η οποία υποδεικνύει ήπια ηπατική βλάβη. Μια πιθανή συσχέτιση μεταξύ της χρήσης της Αλενδρονάτης και της ηπατικής λειτουργίας καθίσταται εμφανής. Ωστόσο, εξαιτίας του μικρού αριθμού δειγμάτων περισσότερες μελέτες είναι απαραίτητες ώστε να διαλευκανθεί αυτή η συσχέτιση.Purpose: Bisphosphonates (BPs) are selective inhibitors of osteoclast mediated bone resorption, used for the treatment of bone disorders as well as for tumors, whereas long-term bisphosphonate use is associated with adverse gastrointestinal effects. The objective of the study is to investigate the possible effects of BPs in hepatic structure. Materials and methods: Specimens from the liver of ten female 12-month old Wistar rats were used as control group and of ten female 12-month old Wistar rats to which Alendronate (Fosamax, Merck) was administered per os for 13 weeks, were used as experimental group. Samples were observed under a Transmission Electron Microscope. Results: In the experimental group, extensive depletion of the glycogen, different sized vacuoles and enlarged sinusoids were found in hepatic cells. Furthermore, there was lack of microvilli of hepatocytes in the Disse’s space. The same findings were reported in all sections of the experimental group. Conclusion: This is the first study of liver structure after the administration of bisphosphonates, with electron microscopy. This report, indicate the presence of mild hepatic damage in liver tissues studied. Our study demonstrates a possible correlation between alendronate administration and hepatic cell function, nevertheless due to the small specimen further research is needed

Sequential Activation of Vulnerable Plaques Endorsing the Inflammatory Hypothesis of Atherosclerosis

A case of sequential activation of vulnerable plaques in two different coronary vessels over the course of 2 days is being presented probably related to inflammation inciting these acute coronary events. Rhythmos 2017;12(4): 69-70

The importance of markers HLA6 and CD68 in placenta tissues of recurrent pregnancy loss

Introduction: Recurrent pregnancy loss of unknown etiology is correlated with immunological factors during pregnancy. Changes in leukocyte subpopulations and HLA (Human Leukocyte Antigen) expression take place in pregnant uterus on both decidua basalis and decidua parietalis in order to carry the semiallogenic embryo. These changes affect the pregnancy course.Objective: Our research is focused to enlighten the immunological changes that take place in the uterus of women with recurrent abortions of unknown etiology during first trimester of pregnancy.Materials and methods: The miscarriage group was obtained from 25 women who miscarried between the ages of 35 to 42 years and controls consisted of 25 healthy women between the ages of 27 to 39 years, who had electively terminated their pregnancies during first trimester of pregnancy. The abortion was processed and specimens taken were studied, using immunohistochemical methods. Specimens were taken from decidua basalis and decidua parietalis. Monoclonal antibodies were used against HLAG (Human Leukocyte Antigen G) and CD68 (Cluster of Differentiation 68). The results were statistically analysed with Mann-Whitney test.Results: HLA-G expression in decidua basalis from miscarriage group was found decreased.CD68 + cell expression was found increased in both deciduas from the miscarriage group.Conclusion: The immunological profile of women with recurrent miscarriage is quite different comparing with controls. A possible role of CD68+cells in RPL was observed .Changes in HLA-G expression was observed

Insulin receptor (IR) expression in human trophoblasts of recurrent pregnancy loss (RPL)

Purpose: Insulin and glucose pathways play a key role to fetal viability and growth. The focus of the study is to investigate the potential differences of immunohistochemical expression of IR in trophoblastic and decidual cells between women who had recurrent pregnancy loss and women that underwent an abortion. Materials and methods: Trophoblastic and decidual tissues from fifty (50) women with elective abortion used as control group and from fifty (50) women with recurrent miscarriages were collected during gestational weeks 6 to 12. IR antibodies were used as immunohistochemical staining markers. Nuclear and cytoplasmic expression was evaluated. Results: No IR immunohistochemical expression was detected in both trophoblastic cells of the implantation site and deciduas basalis of the two study groups. Conclusion: The effort made to enhance our knowledge on the physiology and histology of IR expression in connection with pregnancy was halted because the results were inconclusive. While studying, though, the correlation of recurrent miscarriage with IR expression, it became evident that a lot of hormones and pathways form the weave of gestational pathology and its delicate harmony. Every piece of knowledge may clarify this still obscure field

Secondary Haemophagocytic Lymphohistiocytosis Syndrome (HLH) After Intravesical Instillation of Bacillus Calmette-Guérin (BCG): A Case Report and Review of the Literature

Intravesical bacillus Calmette-Guérin (BCG) instillation is widely used for the treatment of superficial bladder cancer. BCGitis is a serious immune-mediated complication with systematic manifestations and a high mortality rate. Here, we describe a case of a 64-year-old male patient who presented with haemophagocytic lymphohistiocytosis syndrome (HLH) after BCG instillation and was effectively treated with high-dose dexamethasone, intravenous immunoglobulins and anti-tuberculosis treatment

RASSF1A uncouples Wnt from Hippo signalling and promotes YAP mediated differentiation via p73

Transition from pluripotency to differentiation is a pivotal yet poorly understood developmental step. Here, we show that the tumour suppressor RASSF1A is a key player driving the early specification of cell fate. RASSF1A acts as a natural barrier to stem cell self-renewal and iPS cell generation, by switching YAP from an integral component in the β-catenin-TCF pluripotency network to a key factor that promotes differentiation. We demonstrate that epigenetic regulation of the Rassf1A promoter maintains stemness by allowing a quaternary association of YAP–TEAD and β-catenin–TCF3 complexes on the Oct4 distal enhancer. However, during differentiation, promoter demethylation allows GATA1-mediated RASSF1A expression which prevents YAP from contributing to the TEAD/β-catenin–TCF3 complex. Simultaneously, we find that RASSF1A promotes a YAP–p73 transcriptional programme that enables differentiation. Together, our findings demonstrate that RASSF1A mediates transcription factor selection of YAP in stem cells, thereby acting as a functional “switch” between pluripotency and initiation of differentiation