DNA damage checkpoint triggers autophagy to regulate the initiation of anaphase

Abstract

Budding yeast cells suffering a single unrepaired double-strand break (DSB) trigger the Mec1 (ATR)-dependent DNA damage response that causes them to arrest before anaphase for 12-15 h. Here we find that hyperactivation of the cytoplasm-to-vacuole (CVT) autophagy pathway causes the permanent G2/M arrest of cells with a single DSB that is reflected in the nuclear exclusion of both Esp1 and Pds1. Transient relocalization of Pds1 is also seen in wild-type cells lacking vacuolar protease activity after induction of a DSB. Arrest persists even as the DNA damage-dependent phosphorylation of Rad53 diminishes. Permanent arrest can be overcome by blocking autophagy, by deleting the vacuolar protease Prb1, or by driving Esp1 into the nucleus with a SV40 nuclear localization signal. Autophagy in response to DNA damage can be induced in three different ways: by deleting the Golgi-associated retrograde protein complex (GARP), by adding rapamycin, or by overexpression of a dominant ATG13-8SA mutation.