Invariable Ribosome Stoichiometry During Murine Erythroid Differentiation: Implications for Understanding Ribosomopathies

Christos I Papagiannopoulos; Konstantinos A Kyritsis; Konstantina Psatha; Dimitra Mavridou; Fani Chatzopoulou; Georgia Orfanoudaki; Michalis Aivaliotis; Ioannis S Vizirianakis

doi:10.3389/fmolb.2022.805541

Invariable Ribosome Stoichiometry During Murine Erythroid Differentiation: Implications for Understanding Ribosomopathies

Front Mol Biosci. 2022 Feb 3:9:805541. doi: 10.3389/fmolb.2022.805541. eCollection 2022.

Authors

Christos I Papagiannopoulos¹, Konstantinos A Kyritsis¹, Konstantina Psatha^{2

3

4

5}, Dimitra Mavridou^{2

3}, Fani Chatzopoulou^{1

6}, Georgia Orfanoudaki⁵, Michalis Aivaliotis^{2

3

4

5}, Ioannis S Vizirianakis^{1

2

7}

Affiliations

¹ Laboratory of Pharmacology, School of Pharmacy, Aristotle University of Thessaloniki, Thessaloniki, Greece.
² Functional Proteomics and Systems Biology (FunPATh)-Center for Interdisciplinary Research and Innovation (CIRI-AUTH), Thessaloniki, Greece.
³ Laboratory of Biochemistry, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
⁴ Basic and Translational Research Unit, Special Unit for Biomedical Research and Education, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
⁵ Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, Heraklion, Greece.
⁶ Laboratory of Microbiology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
⁷ Department of Life and Health Sciences, University of Nicosia, Nicosia, Cyprus.

Abstract

Heterogeneity of the main ribosomal composition represents an emerging, yet debatable, mechanism of gene expression regulation with a purported role in ribosomopathies, a group of disorders caused by mutations in ribosomal protein genes (RPs). Ribosomopathies, mysteriously relate with tissue-specific symptoms (mainly anemia and cancer predisposition), despite the ubiquitous expression and necessity of the associated RPs. An outstanding question that may shed light into disease pathogenicity and provide potential pharmacological interventions, is whether and how the ribosomal composition is modified during, the highly affected by RP mutations, process of erythroid differentiation. To address this issue, we analyzed ribosome stoichiometry using an established model of erythroid differentiation, through sucrose gradient ultracentrifugation and quantitative proteomics. We found that differentiation associates with an extensive reprogramming of the overall ribosomal levels, characterized by an increase in monosomes and a decrease in polysomes. However, by calculating a stoichiometry score for each independent ribosomal protein, we found that the main ribosomal architecture remained invariable between immature and differentiated cells. In total, none of the 78 Ribosomal Proteins (RPs- 74 core RPs, Rack1, Fau and 2 paralogs) detected was statistically different between the samples. This data was further verified through antibody-mediated quantification of 6 representative RPs. Moreover, bioinformatic analysis of whole cell proteomic data derived out of 4 additional models of erythropoiesis revealed that RPs were co-regulated across these cell types, too. In conclusion, ribosomes maintain an invariant protein stoichiometry during differentiation, thus excluding ribosome heterogeneity from a potential mechanism of toxicity in ribosomopathies and other erythroid disorders.

Keywords: erythropoiesis; mass spectrometry; proteomics; ribosomal proteins; ribosomopathies.