Team ROUAULT-PIERRE

Stress Integration in Normal and Malignant Hematopoietic Stem Cells

In this program, we aim to identify and characterize aberrant splicing events that constitute functional drivers of myelodysplastic neoplasms (MDS), particularly in hematopoietic stem and progenitor cells. Drawing on splicing profiles generated from primary cells of patients carrying SF3B1 or SRSF2 mutations, we have identified several hundred specifically aberrant isoforms absent from normal hematopoietic cells. Building on these human signatures, we are developing targeted screening of mis-spliced genes in MDS in order to identify novel key regulators of hematopoietic stem cell self-renewal, differentiation, and proliferation. The most relevant candidates are then functionally validated in human cellular models, patient-derived xenografts, and conditional murine models. This integrated approach allows specific splicing alterations to be linked to exploitable biological vulnerabilities, and paves the way for precision therapeutic strategies directly grounded in patient-derived cell mechanisms.

Aberrant splicing in MDS results in the continuous production of abnormal transcripts and proteins, generating a chronic proteotoxic load. However, the mechanisms by which hematopoietic stem cells carrying splicing mutations tolerate and adapt to this stress remain poorly understood. This program studies how proteostasis networks are remodeled in normal and mutated hematopoietic stem cells. Building on prior work regarding the sensitivity of hematopoietic stem and progenitor cells to endoplasmic reticulum stress, it integrates RNA splicing analyses and functional approaches in primary human cells. This approach identifies stress adaptation pathways specifically required by mutant clones, while remaining dispensable for normal stem cells. It thereby defines therapeutically exploitable proteostasis vulnerabilities and provides a mechanistic framework for understanding inter-patient heterogeneity in disease progression and treatment responses.

This program explores how the high load of NMD-sensitive transcripts in splicing mutation-bearing MDS can be exploited to induce synthetic lethality. It builds on the observation that modulation of the translation of these aberrant transcripts accentuates proteotoxic stress and disrupts the balance of protein quality control systems in mutated cells. By combining functional approaches and integrated genomic analyses in mutated and non-mutated myeloid models, this program aims to identify specific molecular dependencies that emerge in contexts of exacerbated protein stress. This work allows the definition of selective vulnerabilities of splicing alteration-bearing clones, while preserving normal cells. Ultimately, this axis provides a rational framework for the development of combinatorial therapeutic strategies preferentially targeting mutated cells, and supports the emergence of new preclinical approaches in MDS and other pathologies associated with splicing factor mutations.