Defining determinants of asymmetric cell division (Doctoral thesis)

Πότση, Ντιάνα-Μαρία

The asymmetric cell division constitutes a fundamental biological process through which pluripotent stem cells or progenitor cells can both divide (through mitosis) to produce more stem cells and differentiate into all the specialized cells - ectoderm, endoderm and mesoderm. This kind of division has been thoroughly investigated in evolutionarily simple organisms. However, some critical queries concerning the higher species remain unanswered. This thesis refers to such a query focusing on possible asymmetries in the nuclear lamina, a dense fibrillar network on the surface of the nucleus that affects the architecture of the organelle and seems to participate in the control of gene expression in all metazoans. In the experiments we conducted we used E14 mouse embryonic stem cells. Embryonic stem cells possess the ability of self-renewing indefinitely in the undifferentiated state and differentiate into any cell type. Our goal was to monitor asymmetric cell divisions in this cellular system and determine any quantitative or qualitative differences of A- and B-type lamins. Cells were studied not only in an undifferentiated state but also in a differentiated one. Classic markers of the asymmetric cell division and other cellular elements, such as lamins, were scrutinized during the differentiation procedure, focusing on their symmetric or asymmetric distribution. We carried out both random and directed differentiation experiments in two (2) and three (3) dimensions. Exhausting analysis showed that E14 cells always divide by symmetric dvisions. Therefore, we wanted to examine whether there are any structural asymmetries that affect the micro-architecture of the nuclear lamina or modify its dynamic behavior during mitosis. In order to thoroughly study the dynamic of both A- and B-type lamins, we constructed two cell lines that overexpress these proteins and used them in FRAP experiments. Having as our main aim the monitoring of an asymmetry between two daughter cells, we had to examine actual daughter cells in the stage of early G1 of the cell cycle, during which the nuclear envelope and, therefore, the nuclear lamina, is reorganized. Lamin-overexpressing cells were transfected with the H2B m-cherry plasmid, to ensure that the cells analysed were genuine daughter. These experiments are in progress.
Alternative title / Subtitle: ο ρόλος της πυρηνικής λάμινας
the role of nuclear lamina
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής
Subject classification: Βλαστικά κύτταρα
Keywords: Ασύμμετρη κυτταρική διαίρεση,Εμβρυονικά βλαστικά κύτταρα,Κατευθυνόμενη διαφοροποίηση των βλαστικών κυττάρων,Εμβρυοειδή σωμάτια,Πυρηνική λάμινα,Δυναμική των πρωτεϊνών,Asymmetric cell division,Embryonic stem cells,Directed differentiation of stem cells,Embryoid bodies,Nuclear Lamina,Protein dynamics
Appears in Collections:Διδακτορικές Διατριβές

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