We usually pick recent papers, but occasionally we’ll discuss older papers that we may have missed or that have become relevant to our research.

This week we discussed a 2008 Genes Dev paper from the Calvi lab: Endocycling cells do not apoptose in response to DNA rereplication genotoxic stress (picked By Mahsa) – Free access:

http://genesdev.cshlp.org/content/22/22/3158.full.pdf+html

Calvi et al describe how re-replication (triggered by overexpression of Dup, double-parked) can induce DNA damage in both mitotic and endocycling cells, but only the mitotic cells die. They suggest that the pro-apoptotic genes (hid, grim, reaper) maybe silenced in endoreplicating cells and hence cannot be upregulated by DNA damage cues (Chk2- and p53-dependent). Overall we found this to be an interesting paper. Questions that came up: Why don’t endoreplicating cells die? Can larval endocycling cells tolerate DNA damage and still function? What is the silencing mechanism operating in endoreplicating cells? Why do different endocycling cells behave differently (e.g. hs/gal4-expression of propapoptic genes killed salivary gland cells but had no effect on fat body cells)?