Differentiation stage-specific use of cap-independent and cap-dependent translation initiation in hematopoiesis

  • bioRxiv. 2025 Sep 25:2025.09.24.678136. doi: 10.1101/2025.09.24.678136.
Michael C Mazzola  1  2  3 ,  Ting Zhao  1  2  3 ,  Anna Kiem  1  2  3 ,  Trine A Kristiansen  1  2  3 ,  Karin Gustafsson  1  2  3 ,  Lai Ping Wong  4  5 ,  Emily Scott-Solomon  2  3 ,  Marissa D Fahlberg  6 ,  Sarah Forward  6 ,  Emane Rose Assita  6 ,  Giulia Schiroli  1  2  3 ,  Maris Handley  1  7 ,  Youmna Kfoury  1  2  3 ,  Tsuyoshi Fukushima  1  2  3 ,  Samuel Keyes  1  2  3 ,  Azeem Sharda  1  2  3 ,  Jelena Milosevic  1  2  3 ,  Hiroki Kato  1  2  3 ,  Pavel Ivanov  8  9  10 ,  David B Sykes  1  2 ,  Sheldon J J Kwok  6 ,  Ruslan I Sadreyev  4  5 ,  Vijay G Sankaran  2  11  12  13 ,  Ya-Chieh Hsu  2  3 ,  David T Scadden  1  2  3
Affiliations
  • 1. Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA.
  • 2. Harvard Stem Cell Institute, 7 Divinity Avenue, Cambridge, MA 02138, USA.
  • 3. Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.
  • 4. Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA.
  • 5. Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
  • 6. LASE Innovation Inc., 335 Bear Hill Road, Waltham, MA 02451, USA.
  • 7. HSCI-CRM Flow Cytometry Core Facility, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA.
  • 8. Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA.
  • 9. Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
  • 10. Harvard Initiative for RNA Medicine, Boston, MA 02115, USA.
  • 11. Broad Institute of MIT and Harvard, Cambridge, MA, USA.
  • 12. Division of Hematology / Oncology, Boston Children's Hospital and Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, 02115, USA.
  • 13. Howard Hughes Medical Institute, Boston, MA, USA.
PMID: 41040404 DOI: 10.1101/2025.09.24.678136
Abstract

Cell stress can increase the use of m7G-cap-independent, IRES-mediated translation initiation relative to cap-dependent translation (IRES/Cap). Reporters that quantify IRES/Cap have demonstrated differential activity across cultured cell types and stress conditions. By generating an IRES/Cap reporter mouse, we were able to systematically evaluate IRES/Cap across distinct tissues and cell types during physiological stresses and lineage commitment. Caloric stress invoked the expected boost in IRES/Cap translation regardless of differentiation state, but unexpectedly IRES/Cap progressively increased during hematopoietic and epithelial (hair follicle) differentiation under normal, homeostatic conditions. This was independent of total protein output or cell cycle. Even within cells of a given differentiation state, cells with lower relative-IRES utilization had markedly higher multipotent capability in vivo. The RNA processing protein PTBP1 is a mediator of this translation initiation preference. Therefore, low IRES/Cap is a signature of high stemness and suggests modulation of translation initiation participates in cell differentiation state.

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