Dissertation committee:
Ειρήνη Λεκανίδου Ομότιμη Καθηγήτρια Τμήμα Βιολογίας ΕΚΠΑ (Επιβλέπουσα) , Διαμαντής Σίδερης Αναπληρωτής Καθηγητής Τμήμα Βιολογίας ΕΚΠΑ, Κώστας Ιατρού Ερευνητής Α ΕΚΕΦΕ Δημόκριτος
Summary:
The objective of this thesis was to study members of the Ankyrin-repeat protein
family, Ank proteins, of the CcBV polydnavirus (Cotesia congregata bracovirus),
which lives as a provirus in the hymenopteran species Cotesia congregata, a
wasp known to parasitize the lepidopteran Manduca sexta. Using transient
transfections and Western immunoblotting, expression levels of six Ank proteins
were found to be unequal, whereas according to immunofluorescence experiments,
their subcellular distribution varied among them.
Employing functional assays we tested the effect of Ank proteins on Rel/NF-κΒ
transcription factors which, through the Imd and Toll signalling pathways,
regulate the transcription of genes implicated in insect immunity. In a
lepidopteran cell line we transiently overexpressed silkworm Rel/NF-κΒ
transcription factors, Relish1 and RelB. Five out of the six Ank proteins
variably inhibited transcription factor R1d2, a constitutively active Relish1
mutant participating in the Imd signalling pathway. On the contrary, the
activity of RelΒ, a factor activated by the Toll pathway, was inhibited only by
one Ank family member. The observed differences between the two signalling
pathways suggest that different Anks show specificity against their targets and
imply that most CcBV Anks target the Imd pathway, indicating the importance of
this pathway in anti-viral responses.
Keywords:
Ankyrin repeats, Parasitization, ΝF-κΒ factors, CCBV virus, Imd pathway
