Invariable stoichiometry of ribosomal proteins in mouse brain tissues with aging

• Published in: Proceedings of the National Academy of Sciences - PNAS 2019-11, Vol.116 (45), p.22567-22572
• Main Authors: Amirbeigiarab, Susan, Kiani, Parnian, Sanchez, Ana Velazquez, Krisp, Christoph, Kazantsev, Andriy, Fester, Lars, Schlüter, Hartmut, Ignatova, Zoya
• Format: Article
• Language: English
• Subjects: Age; Aging; Aging (natural); Aging - genetics; Aging - metabolism; Animal tissues; Animals; Biological Sciences; Brain; Brain - growth & development; Brain - metabolism; Cerebellum; Composition; Female; Gene Expression Regulation, Developmental; Heterogeneity; Invariants; Male; Mice; Molecular machines; Noise measurement; Protein composition; Proteins; Proteomics; Ribosomal proteins; Ribosomal Proteins - chemistry; Ribosomal Proteins - genetics; Ribosomal Proteins - metabolism; Ribosomes; Specialization; Stoichiometry; Variation
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1912060116

Across phyla, the ribosomes—the central molecular machines for translation of genetic information—exhibit an overall preserved architecture and a conserved functional core. The natural heterogeneity of the ribosome periodically phases a debate on their functional specialization and the tissue-specific variations of the ribosomal protein (RP) pool. Using sensitive differential proteomics, we performed a thorough quantitative inventory of the protein composition of ribosomes from 3 different mouse brain tissues, i.e., hippocampus, cortex, and cerebellum, across various ages, i.e., juvenile, adult, and middle-aged mouse groups. In all 3 brain tissues, in both monosomal and polysomal ribosome fractions, we detected an invariant set of 72 of 79 core RPs, RACK1 and 2 of the 8 RP paralogs, the stoichiometry of which remained constant across different ages. The amount of a few RPs punctually varied in either one tissue or one age group, but these fluctuations were within the tight bounds of the measurement noise. Further comparison with the ribosomes from a high-metabolic-rate organ, e.g., the liver, revealed protein composition identical to that of the ribosomes from the 3 brain tissues. Together, our data show an invariant protein composition of ribosomes from 4 tissues across different ages of mice and support the idea that functional heterogeneity may arise from factors other than simply ribosomal protein stoichiometry.