Eph receptors, such as EphA4 and EphB3, which are a
subfamily of the Tyr kinase receptor superfamily, have been shown, in previous
studies, to function as dependence receptors; in the absence of their
respective ligand these trans-membrane receptors signal for programmed cell
death, yet their mechanism for cell death induction has not been explicitly
studied. To shed light on their function, we used mouse embryonic fibroblasts
(MEFs) from EphA4-/-/EphB3-/- animals. The primary goal
was to establish optimal conditions that would allow us to measure Eph-induced
cell death in these cells. Afterwards, TrypanBlue exclusion assays were
performed to quantify cell death in cells expressing either EphA4 alone, EphB3
alone, or EphA4/EphB3 together; the results were used to establish whether
EphA4/EphB3 can cause effective apoptosis individually or if there is
synergistic function between EphA4-EphB3 producing even greater cell death. Although
inconclusive, our results suggest that EphB3 under our conditions is able to
initiate apoptosis on its own in the absence of its respective ligand. Yet,
further tests need to be conducted to better understand the function of EphA4
alone, as well as EphA4 and EphB3 in tandem.
