ATM controls DNA repair and mitochondria transfer between neighboring cells.

Intercellular communication is essential for multicellular tissue vitality and homeostasis. We show that healthy cells message protective signals through direct cell-cell connections to adjacent DNA-damaged cells in a microtubule-dependent manner. In DNA-damaged cells, mitochondria restoration is facilitated by fusion with undamaged mitochondria from healthy cells and their DNA damage repair is optimized in presence of healthy cells. Both, mitochondria transfer and intercellular signaling for an enhanced DNA damage response are critically regulated by the activity of the DNA repair protein ataxia telangiectasia mutated (ATM). These healthy-to-damaged prosurvival processes sustain normal tissue integrity and may be exploitable for overcoming resistance to therapy in diseases such as cancer.