Fundamental and Experimental Biology · Sep 29, 2026
Detection of small discrete 5'-terminal fragments of 18S rRNA in mouse cells
By Malysheva AA, Kazanbassov T, Lopatchenko T et al.
Protein biosynthesis is a critically important biosynthetic process. With age, destructive changes in ribosome structure can accumulate, leading to the synthesis of misfolded polypeptides and a decrease in regenerative potential and cell viability. Therefore, there is a need to develop universal molecular markers for ribosome integrity. A DNA construct was designed to produce DIG-labeled RNA probes aimed at detecting 5'-terminal fragments of mammalian 18S rRNA. RNA isolated from the liver, lungs, kidneys, and skeletal muscles of young and aging mice was analyzed by Northern blotting using these probes. Small, discrete 5′-terminal fragments of 18S rRNA, similar to the stress-induced 5′18SrRF75 and 5′18SrRF135 molecules found in plants, were identified in mouse cells. The concentration of these fragments in lung and muscle cells was significantly higher than in liver and kidney cells. A notable difference was observed among the kidneys, lungs, and skeletal muscles of young (3 months) versus aging (over two years) animals. These results highlight the universality of the molecular mechanisms underlying the discrete fragmentation of 18S rRNA. Such mechanisms likely play a role in regulating protein biosynthesis during stress. The small fragments 5′18SrRF75 and 5′18SrRF135 could serve as universal markers for the destruction of the translational apparatus.