ИСТИНА

Ribophagy is a specific type of autophagy that is needed for the degradation of ribosomes. This process is necessary for the removal of defective ribosomes, the function of which can be impaired due to the action of translation inhibitors or other stress factors. At present, a small number of ribophagy receptors involved in this process are known, the key one of which is the NUFIP1 protein 'Previously published in: Gregory A. Wyant et al. (2018) Science 360,751758'. Studying the molecular mechanism of ribophagy remains is an urgent task. To identify the genes involved in the ribophagy process, we created a fluorescent reporter (a cell line with ribosomes containing RPL29mCherryGFP) and performed a genomewide CRISPR/Cas9 screening using the Brunello lentiviral library. Among the genes that were highly significant in the screening results was ubiquitin ligase TRIM25. We showed that TRIM25 specifically binds to the ribosome upon induction of ribophagy using cycloheximide (CHX). It is known from literature data that TRIM25 is involved in the antiviral protection of the cell, regulating the immune response and degradation of viral components 'Previously published in: Shang Z. et al. (2024) Nat Commun 15, 4127; Choudhury N. et al (2022) Nucleic Acids Res 50, 70977114'. To test whether viral infection could affect TRIM25 binding to the ribosome, we treated cells with poly(I:C), a synthetic analogue of doublestranded RNA that serves as a model of viral infection. This experiment confirmed that TRIM25 binds to the ribosome under conditions mimicing viral infection. Thus, we have shown that under stress conditions, such as cycloheximide treatment or viral infection, ribosomal ubiquitination occurs, which is mediated by the activity of TRIM25. Considering that ubiquitin ligases of this family are involved in the cellular antiviral response, we suggest that activation of ribophagy may be part of the cellular defense mechanism against viral infection