Physiological roles of the Ribotoxic Stress Response

2026-07-22

The ribotoxic stress response (RSR) surveys the structural and functional integrity of ribosomes and is triggered by diverse groups of ribotoxins (e.g. ricin), UV irradiation and some chemotherapeutics. When presented with impaired ribosomes, the proximal MAPKKK ZAK activates MAP kinases p38 and JNK to initiate a powerful inflammatory response. This signalling contributes to the detrimental reactions to ribotoxins and fatal side effects of cancer therapy. However, despite decades of research into the RSR, the physiological relevance of the underlying pathway in whole organisms is unknown. I hypothesize that the RSR constitutes a general translation quality control pathway and hence I aim to uncover the physiological and pathological implications of RSR impairment in mice and nematodes. In one line of investigation, I will elucidate the connections between UV radiation and RSR-mediated p38 activation. I hypothesize that this signalling pathway is critical for sunlight-induced skin inflammation and development of skin cancers of different cellular origins. Rewardingly, we found that cells from our ZAK knockout (KO) mice are refractory to UV-induced p38 activation, which is a significant contributor to skin cancer development. My team has also observed deregulation of protein translation in RSR-deficient human and mouse cells, and a reduced lifespan of ZAK KO nematodes. Thus encouraged, I will determine the impact of the RSR pathway on cancer development and aging processes in mice, and I will unravel the molecular connections between defective ribosomes, RSR activation and regulation of translation. Finally, I am in a unique position to evaluate the RSR as a putative drug target and I will investigate the potential of ZAK inhibition to treat or prevent skin cancer, and to remedy inflammation arising from infection with ribotoxin-producing bacteria. In sum, PHYRIST will yield the first detailed insight into the in vivo relevance of the ribotoxic stress response.

Denmark

2026-02-01