DDIT3 and heart failure: CHOP (encoded by Ddit3) is a transcription factor highly induced during the UPR and deletion of the Ddit3 gene has provided protection against tissue damage and disease, including atherosclerosis25 and renal damage caused by the UPR-inducing toxin tunicamycin.26 We therefore examined whether absence of Ddit3 impacted on development of irradiation-induced heart failure and weight loss.