Genexpressionsmuster in Thrombozyten und Thrombozyten-Vorläuferzellen / eingereicht von Sandra Rieger

• VerfasserIn: Rieger, Sandra
• Place / Publishing House: 2002
• Year of Publication: 2002
• Language: German
• Classification: 42.20 - Genetik
• Physical Description: 122 Bl.; Ill., graph. Darst.
• Notes: Abweichender Titel laut Übersetzung der Verfasserin/des Verfassers

ger: Background: The hemostatic system is of essential importance and platelets (PLT), formed by their precursors (megakaryocytes; MEG) in bone marrow are central components for the maintenance of the vascular integrity. In this study mRNA quantities of PLT specific genes (GPIb, GPIIla, P-selectin, vWF) were measured during differentiation of MEG in tissue culture, in PLT of healthy controls and clonal PLT of patients with essential thrombocythemia (ET; 30% thrombosis). Furthermore, we investigated gene transcripts which are up- or downregulated in clonal versus polyclonal PLT population by differential display analysis (DD).<br />We evaluated the association of two frequent polymorphisms in protein S and P-selectin gene with clonal PLT.<br />Patients and methods: Tissue cultures were performed in human megakaryoblastic cells (MEG-01), with and without phorbolester (TPA).<br />Unstimulated and TPA treated cells were isolated on day 0,2,4,6 and 8, used for mRNA extraction and eDNA synthesis. MEG-O1 cells and polyclonal and clonal PLT of 20 healthy controls and 12 ET patients were analysed with Real-time PCR system (LightCyclerTM) to quantify expression of PLT specific genes. With DD eDNA fingerprints of clonal versus polyclonal PLT were compared. The prevalence of the Pro626Pro polymorphism in protein S and the Pro715Thr polymorphism in P-selectin gene was determined in 80 patients with ET and 80 healthy controls. The polymorphisms were then used to study allelic expression of these genes.<br />Results: MEG-01 cells showed significant increase of mRNA following TPA treatment (P-selectin 30x; vWF 20x, GPIb 2x) to a maximum on day 8.<br />GPIIIa mRNA could already be detected on day 2 in 10fold increased concentration. In ET patients we observed a 100times increased expression of vWF and GPIIIa mENA compared to healthy controls. By DD we identified an increased mRNA expression of CD55 in a patient with clonal PLT. Quantification of CD55 mRNA showed elevated mRNA levels only in few ET patients. Polymorphisms in protein S and P-selectin gene were not associated with ET. Allelic expression analysis of protein S and P-selectin showed expression of both alleles in clonal PLT which indicates transcription of both alleles in every MEG.