Downregulation of the essential Rrp44 ribonuclease causes extensive ultra-structure cell modifications in Trypanosoma brucei

Cesaro, G.; Hiraiwa, P. M.; Carneiro, F. R. G.; Rouam, V.; Legrand, P.; Conesa, J. J.; Soares, M. J.; Refregiers, M.; Pereiro, E.; Guimaraes, B. G.; Jamme, F.; Zanchin, N. I. T.

doi:10.1101/2020.02.29.971424

bioRxiv · 10.1101/2020.02.29.971424

Downregulation of the essential Rrp44 ribonuclease causes extensive ultra-structure cell modifications in Trypanosoma brucei

Cesaro, G.·Hiraiwa, P. M.·Carneiro, F. R. G.·Rouam, V.·Legrand, P.·Conesa, J. J.·Soares, M. J.·Refregiers, M.·Pereiro, E.·Guimaraes, B. G.·Jamme, F.·Zanchin, N. I. T.

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Abstract

Rrp44/Dis3 is an essential protein conserved in all eukaryotes that functions in the maturation of many different RNA precursors and RNA surveillance. The Trypanosoma brucei Rrp44/Dis3 homologue (TbRRP44) is required for maturation of pre-rRNA, spliced leader, and U3 snoRNA precursors. Its depletion leads to inhibition of cell proliferation and eventually to cell death. In this work, we showed that TbRRP44 depletion causes a massive expansion of acidic and lysosome-derived vacuoles, enlargement of cell and nuclei sizes without changes in DNA content, mitochondrial inactivation, and autophagy induction. Consistently, 3D reconstructions using cryo-soft X-ray tomography revealed extreme vacuolation of the cytoplasm and numerous cellular alterations, including an increase in size and number of calcium-containing vesicles and lipid droplets. These multiple defects indicate that a combination of alterations converge to induce lysosome expansion. With time, the cytoplasm is taken up by lysosome-derived vacuoles, which may be a final stage leading to the cell death triggered by TbRRP44 depletion. These studies provide the first evidence on the ultra-structure cell modifications caused by deficiency of this essential ribonuclease in T. brucei.

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Cesaro, G., Hiraiwa, P. M., Carneiro, F. R. G., Rouam, V., Legrand, P., Conesa, J. J., Soares, M. J., Refregiers, M., Pereiro, E., Guimaraes, B. G., Jamme, F., Zanchin, N. I. T.. 2020-02-29. Downregulation of the essential Rrp44 ribonuclease causes extensive ultra-structure cell modifications in Trypanosoma brucei. https://doi.org/10.1101/2020.02.29.971424

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