Browsing by Subject "angiogeneesi"

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  • Huuska, Nora (Helsingin yliopisto, 2018)
    TAUSTA: Verisuonten uudismuodostuksen, läpäisevyyden ja rappeutumisen säätelyssä avainasemassa on Angiopoietiini-Tie-järjestelmä, joka koostuu angiopoietiineista 1-4 (Ang1-4) sekä niiden reseptoreista Tie1 ja Tie2. Ang1:n aikaansaama Tie-reseptorien aktivaatio johtaa verisuonten endoteelisolujen välisten sidosten tiukentumiseen ja homeostasian ylläpitoon. Ang2 puolestaan pystyy salpaamaan Tie2-reseptorin, jolloin verisuonten läpäisevyys lisääntyy ja endoteeli alkaa rappeutua. Paradoksaalisesti Ang2 pystyy myös aktivoimaan Tie1:n tietyissä olosuhteissa, jolloin verisuonten läpäisevyys vähenee. TAVOITTEET: Tämän tutkimuksen tarkoituksena oli selvittää Ang2:n yli-ilmentymisen ja Tie1-poistogeenisyyden vaikutusta verisuonten läpäisevyyteen hiirten keuhkokudoksessa. Lisäksi tutkittiin anti-Tie1 (DX2240) ja anti-Ang2 (MEDI3617) vasta-aineiden vaikutusta verisuonten läpäisevyyteen ja tulehdusreaktion voimakkuuteen LPS-indusoidussa verenmyrkytyksessä. MENETELMÄT: Määritettiin valkosolujen, punasolujen ja fibrinogeenin määrä immunohistokemiallisten värjäysten avulla Ang2:ta yli-ilmentävien hiirten, Tie1-poistogeenisten hiirten ja näiden yhdistelmähiirten keuhkoissa. Lisäksi määritettiin keuhkolaskimoiden seinämien paksuus sekä nanopartikkelien vuoto anti-Tie1 ja anti-Ang2 vasta-aineita saaneiden hiirten keuhkoissa tulehduksen ja verisuonten läpäisevyyden arvioimiseksi. TULOKSET: Ang2:n yli-ilmentymisen ja Tie1-poistogeenisyyden ei havaittu aiheuttavan merkittävää eroa verisuonten läpäisevyydessä. Anti-Tie1 ja anti-Ang2-vasta-aineet eivät myöskään vähentäneet merkittävästi verisuonten läpäisevyyttä verenmyrkytyksessä.
  • Taskinen, Juuso (Helsingin yliopisto, 2019)
    Human umbilical vein endothelial cells are responsible for maintaining and forming new vessels from existing ones, in a biological process called sprouting angiogenesis. Sprouting angiogenesis is a crucial mechanism for the resolution of hypoxia and normal development of tissues. It also plays a key role in internal plague hemorrhages, which can lead to embolisms and other cardiovascular complications. Angiogenesis is also crucial for cancer development. Sprouting angiogenesis is initiated by hypoxic tissue excreted vascular endothelial growth factor gradient, which induces normal endothelial cells into either a proliferative stalk cell or a signal sensing tip cell phenotype. Both of these cell types depend on the rapid flow of lipids to their plasma membrane, either to form plasma membrane protrusions in tip cells or as new plasma membrane material in dividing stalk cells. This flow is envisioned to involve both vesicle-mediated and non-vesicular mechanisms. A major non-vesicular route of lipid transfer occurs at membrane contact sites via lipid transport proteins. Furthermore, lipids can be transported to the plasma membrane by the direct fusion of vesicles or endosomes with the plasma membrane This thesis set out to explore the role of two membrane contact site proteins, oxysterol-binding protein- related protein 2 and protrudin, in angiogenesis and lipid transfer. Their role was examined by RNA-sequencing transient knock-down samples of these proteins in HUVECs. The RNA-sequencing data was examined by differential expression, gene ontology overrepresentation and gene set enrichment analyses. Gene expression analysis provided almost 10 000 significantly changed transcripts (adjusted p-values < 0.05), in each silenced cell type. The distribution of differentially expressed genes in oxysterol-binding protein- related protein 2 silenced cells, is skewed toward negative fold changes, whereas the distribution of differentially expressed genes in protrudin silenced samples is normally distributed. The results also show significant changes in gene ontologies related to proliferation, cell cycle, angiogenesis as well as hypoxia in both sample types. Gene set enrichment analysis showed upregulation in angiogenesis related pathways, such as the PI3K-Akt and MAPK pathways, in both samples. Significant downregulation was present in cell cycle related pathways and cholesterol biosynthesis pathway in both ORP2 and protrudin silenced samples.
  • Jokinen, Birgitta (Helsingfors universitet, 2010)
    Angiogenesis may be regarded as one of the most important phenomena involved in basic physiology as well as in numerous pathological conditions. Angiogenesis is a multistep process involving the balance of pro- and con-angiogenic factors. Several studies have suggested that angiogenesis is regulated in vitro and in vivo by peptides thymosin ȕ4 (Tȕ4) and tetrapeptide Ac-SDKP (N-acetyl-seryl-aspartyl-lysyl-proline). There are also studies supporting the view that Ac-SDKP, a peptide fragment is released from the proline-containing C-terminus of Tȕ4 (43-mer) by hydrolyzing prolyl oligopeptidase (POP). POP is a widely existing serine protease cleaving oligopeptides of no longer than 30 amino acids. Thus, Tȕ4 should first be cleaved into a shorter peptide by some other, yet unknown peptidase. POP has been mostly studied in memory and learning disorders as well as in neurodegenerative diseases. The true physiological character of POP is still unresolved. In this Master's thesis, the associations of the factors involved in angiogenesis are reviewed in the literature part as well as the character, presence and function of the angiogenic molecules 7ȕ4, Ac-SDKP and POP. In the experimental part attempts were made to find whether POP and Tȕ4 increase Ac-SDKP formation and capillary tube network and consequently, whether the POP activity, tetrapeptide and capillary formation could be inhibited by the proline-spesific POP inhibitor KYP-2047. The study had two phases. The first phase included POP activity and Ac-SDKP measurements(time period 0-180 min) with Wistar rat kidney homogenates. Study groups were 0,1 and 0,5 µM KYP-2047 (+2 µM Tȕ4), 1:20 (0.625 µM) human recombinant POP (+ 2 µM Tȕ4), 2 µM 7ȕ4 (pos. control) and raw homogenate (neg. control). The second phase involved the study of capillary formation (time period 0-180 min) with primary endothelial HUVECs on a 48-well plate seeded with 50 000 cells/well on an extracellular membrane mimicking MatrigelTM Matrix dissolved in DMEM. Study groups treated with fetal bovine serum and antibiotics were 5 and 10 µM KYP-2047 (+4 µM Tȕ4), 1:20 (0.625 µM) human recombinant POP (+4 µM Tȕ4)4 µM Tȕ4 (pos. control) and DMEM (neg. control). The wells were cultured and capillary formation photographed with a light microscope using a digital camera. All experiments were repeated four times, and each study group in wells was measured in triplicate. Enclosed capillaries were counted manually and statistical tests were performed. 7ȕ4 along with POP participated in the formation of AC-SDKP in the kidney homogenates. Cultures of primary endothelial cells on Matrigel resulted in clear capillary formation in Tȕ4 and POP groups. KYP-2047 had a strong POP-inhibitory activity on antiangiogenesis throughout the study resulting. Obviously, underlying mechanisms of angiogenesis and the function of the interaction between POP, Tȕ4 and Ac-SDKP in capillary formation require further studies.