Gene dosage effect of CUX1 in a murine model disrupts HSC homeostasis and controls the severity and mortality of MDS

Abstract

Monosomy 7 (-7) and del(7q) are high-risk cytogenetic abnormalities common in myeloid malignancies. We previously reported that CUX1 , a homeodomain-containing transcription factor encoded on 7q22, is frequently inactivated in myeloid neoplasms, and CUX1 myeloid tumor suppressor activity is conserved from humans to Drosophila. CUX1 -inactivating mutations are recurrent in clonal hematopoiesis of indeterminate potential as well as myeloid malignancies, in which they independently carry a poor prognosis. To determine the role for CUX1 in hematopoiesis, we generated 2 short hairpin RNA-based mouse models with ∼54% (Cux1 mid ) or ∼12% (Cux1 low ) residual CUX1 protein. Cux1 mid mice develop myelodysplastic syndrome (MDS) with anemia and trilineage dysplasia, whereas CUX1 low mice developed MDS/myeloproliferative neoplasms and anemia. In diseased mice, restoration of CUX1 expression was sufficient to reverse the disease. CUX1 knockdown bone marrow transplant recipients exhibited a transient hematopoietic expansion, followed by a reduction of hematopoietic stem cells (HSCs), and fatal bone marrow failure, in a dose-dependent manner. RNA-sequencing after CUX1 knockdown in human CD34 + cells identified a -7/del(7q) MDS gene signature and altered differentiation, proliferative, and phosphatidylinositol 3-kinase (PI3K) signaling pathways. In functional assays, CUX1 maintained HSC quiescence and repressed proliferation. These homeostatic changes occurred in parallel with decreased expre…