Thermosensitivity of translation underlies the mammalian nocturnal-diurnal switch

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.06.22.546020v1?rss=1 Authors: Beale, A. D., Rzechorzek, N. M., Mihut, A., Zeng, A., Smyllie, N. J., Pilorz, V., Richardson, R., Bertlesen, M. F., James, N. R., Fazal, S. V., Voysey, Z., Pelletier, J., Crosby, P., Peak-Chew, S. Y., Lancaster, M. A., Hut, R. A., O'Neill, J. S. Abstract: Early mammals were nocturnal until the Cretaceous-Paleogene extinction facilitated their rapid expansion into daytime niches. Diurnality subsequently evolved multiple times, independently, but the mechanisms facilitating this switch are unknown. We found that physiological daily temperature shifts oppositely affect circadian clock rhythms in nocturnal versus diurnal mammals. This occurs through a cell-intrinsic signal inverter, mediated by global differences in protein phosphorylation, and effected at the level of bulk protein synthesis rates, with diurnal translation rate being less thermosensitive than nocturnal. Perturbations that reduce translational initiation or mTOR activity are sufficient to trigger the nocturnal-to-diurnal switch at the cellular, tissue, and organismal scale. Our results suggest a convergent selection pressure to attain diurnality by reducing the effect of temperature-dependent changes in protein synthesis on circadian clocks. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC