טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentLia Mittelman
SubjectActivated Ras1 induces Morphological and Molecular Changes
in Drosophila Schneider 2 Cells
DepartmentDepartment of Biology
Supervisor Assistant Professor Lev Ze'ev


Abstract

Developmental fate of cells is often established by activating Receptor Tyrosine Kinases family and an increase in the activity of Ras and its downstream effectors. Preliminary results in our lab indicated that S2 cells undergo morphological changes following Ras1 activation. The aims of this study were to study the effect of activated Ras1 on Schneider line 2 (S2) transfected cells and: 1. To define the morphological, functional and molecular changes appearing in these cells; 2. In light of the observed changes, to evaluate the biological change in the system.

S2 cells are macrophage-like cells that following expression of Ras1 G12V, attach to the plate, flatten, double their normal size, generate long processes and stop dividing. These morphological changes may reflect an induced differentiation process.


A stable S2 cell line expressing activated Ras1 driven by the metallothionein promoter (S2-Ras1 cells) was established. We found that these cells were vital and not apoptotic although not dividing, and their phagocytosis function decreased as shown using FITC- labeled E.coli.

Differentiation of cells is characterized by growth arrest and differences in gene expression. Utilizing gene microarray analysis we found that in the induced S2-Ras1 cells 536 genes were up regulated and 537 genes down regulated compared with S2 cells. For example, actin binding and cell adhesion genes were up regulated.  DNA replication and G2-to-M transition of the cell cycle

were down regulated. Both the Ras\MEK\ERK pathway and the JNK pathway were activated. Interestingly, changes in expression level of hemopoietic and peripheral nervous system markers were also observed. The embryonic originated S2 cells might show partial differentiation toward several lineages.

Finally, this study demonstrates that the S2-Ras1 system may be used to complement and supplement the in vivo studies of specific routes to differentiation.