טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBen-Zvi Doreen
SubjectThe Developmental Role of cg8965 in Drosophila
melanogaster
DepartmentDepartment of Medicine
Supervisor Professor Adi Salzberg
Full Thesis textFull thesis text - English Version


Abstract

The objective of this work was to provide insight into the hitherto unknown function of the gene cg8965. Our interest in cg8965 was kindled by the identification of a physical interaction of Cg8965 with Ras and of Cg8965 with Delilah (Dei).

Cg8965’s possession of Ras association domains (RA) and its ability to bind Ras suggests that Cg8965 may have a role in the EGFR pathway. The fact that cg8965 is expressed in the eye and wing imaginal discs where EGFR plays a major role, also contributes to this assumption. The results of this research indeed suggest that cg8965’s function is related to EGFR. Firstly, the expression pattern of cg8965 in the wing resembles that of EGFR. Secondly, cg8965‘s overexpression in the wing results in intermittent veins, a phenotype shared by EGFR loss-of-function. Thirdly, rescue experiments performed in the wing and the eye point to a functional link between cg8965 and Ras, which is an effector of the EGFR pathway. The results indicate that the nature of this relationship is dependent upon the developmental context: cg8965 acts as an agonist of Ras in cell fate determination, while it acts as an antagonist of Ras during cell proliferation.

dei is a transcription factor, which is expressed mainly in cells that have a role in attachment and has been shown to be a positive regulator of β-integrin expression, which mediates adhesion. Physical association between Dei and Cg8965 has been documented in the literature. In order to prove a functional link between cg8965 and dei, this work concentrated on two model systems: the wing and the Lateral Chordotonal Organ (LCh5), which is a sensory organ. Although this work revealed that the expression pattern of cg8965 overlaps that of dei in some of the LCh5 cells, the results did not reveal any functional link between cg8965 and dei in the LCh5, since the morphology and β-integrin expression of the LCh5 proved impervious to changes in cg8965 expression and to concurrent changes in cg8965 and dei expression. Thus, cg8965 does not appear to have a crucial role in LCh5 formation and does not operate with dei in its development. However, in the wing not only do the expression patterns of cg8965 and dei overlap, but their mutants also have similar phenotypes. From this it can be surmised that the wing may be the site of a functional link between cg8965 and dei.