Μελέτη των πυρηνικών υποδοχέων που ενεργοποιούνται από πολλαπλασιαστές υπεροξειδιοσωμάτων (peroxisome proliferator-activated receptors - PPARs) σε καλλιεργούμενα είδη ιχθύων

• Main Authors: Μπουκουβάλα, Ευριδίκη, Boukouvala, Evridiki
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: Aristotle University Of Thessaloniki (AUTH) 2006
• Subjects: Πυρηνικοί υποδοχείς; Μεταβολισμός λιπιδίων; Μεταγραφικοί παράγοντες; Τσιπούρα; Λαβράκια; Περιοχές DBD και LBD; Προσδέτες; Nuclear receptors; PPARs; Lipid metabolism; Transcription factors; Sea bream; Sea bass; DBD and LBD domains; Ligands; Φυσικές Επιστήμες; Βιολογία; Natural Sciences; Biological Sciences; Salmo salar
• Online Access: http://hdl.handle.net/10442/hedi/15306; https://doi.org/10.12681/eadd/15306

My thesis was part of a European research project which intention was the study of transcription control of lipid metabolism in farmed fish and especially in sea bream (Sparus aurata), sea bass (Dicentrarchus labrax), salmon (Salmo salar) and plaice (Pleuronectes platessa). For this purpose we initially performed the cloning and analysis of PPARs in these species. PPARs are ligand-inducible transcription factors belonging to the nuclear hormone superfamily. We also studied PPARs’ tissue expression profile and the properties of their two basic domains DBD and LBD. At the beginning, we isolated and cloned parts of the three PPAR isotypes genes, α, β and γ from both species and part of the second isoform of sea bream PPARα gene. Sequence analysis of these genomic fragments revealed significant homology with the mammalian PPAR genes. To confirm that these isolated genomic fragments constitute parts of functional genes we also isolated and cloned the cDNAs of sea bream and sea bass PPARs. We amplified with RT-PCR their coding regions as well as parts of the 3’ and 5’ untranslated regions. The amino acid sequences of fish PPARs also revealed high homology with mammalian and amphibian homologs. The expression profile of PPARs was determined by the RNase protection assay. The results demonstrate that sea bream and sea bass PPARs present similarities and differences with the mammalian PPARs pattern. This maybe indicates the physiological variations between fish and mammals. Using the Electrophoretic Mobility Shift Assay (EMSA) we studied the abilities of sea bream, sea bass, plaice and salmon PPARs to form heterodimers with RXR and recognize and bind to well-characterized or potential PPAR response elements. The fish PPARs were able to form heterodimers with RXR and bind to DR-1 response elements we tested. Thus, the properties of PPARs’ DBD and LBD domains are conserved in lower evolutionally vertebrates. Finally, through CoActivator-Dependent Receptor Ligand Assay (CARLA) we identified compounds that can act as ligands ...