Loss of CDKN1B induces an age-related clonal hematopoietic disorder via Notch2 activity dysregulation

Abstract

List of abbreviations AML acute myeloid leukemia CDK cyclin dependent kinase CHD clonal hematopoietic disorder CNA copy number alteration EDTA ethylenediamine tetraacetic acid G0 Gap 0 GSI γ-secretase inhibitor HSC hematopoietic stem cell IHC immunohistochemistry KO knock-out LPE low protein expression MCH mean corpuscular hemoglobin MCV mean corpuscular volume MDS myelodysplastic syndromes MEF mouse embryo fibroblast MPO myeloperoxidase RBC red blood cell RBPJ recombinant binding protein-J WT wild type Dear Editor, The tumor suppressor gene CDKN1B, encoding for the p27Kip1 (p27) protein, defines the smallest region of deletion on chromosome 12p13 described in clonal hematopoietic disorders (CHDs) [ 1]. Yet, its role in adult mice and in the onset/progression of CHDs has not been studied in depth, although a fusion construct of mVenus-p27K-, acting as biomarker of G0 phase of the cell cycle, has been used to discriminate dormant and active hematopoietic stem cells (HSCs) in 48 weeks-old mice [ 8]. Splenocytes from 1Y Cdkn1bKO mice showed a decrease in the G1 population (Supplementary Figure S1C), with a highly significant reduction in CD45R+CD19+ B-lymphocytes, and no differences in the number of CD3+ and CD4+CD8+ T cells (Figure 1A-B, Supplementary Figure S1D-E). Abbreviations: WT, wild-type; KO, knock-out; 1Y, 1-year old; FACS, fluorescence-activated cell sorting; SD, standard deviation; IHC, immunohistochemistry; CFU, colony forming unit; CFU-E, colony forming unit-erythroid; CFU-GM, colony forming unit-granulocyte monocyte; CFU-GEMM, colony forming units-granulocyte, erythrocyte, monocyte, megakaryocyte; MPO, myeloperoxidase; qRT-PCR, quantitative reverse transcription polymerase chain reaction; A.U., arbitrary units; ChIP, chromatin immunoprecipitation; 8W, 8-weeks old; EDTA, ethylenediamine tetraacetic acid; RBPJ, recombining binding protein suppressor of hairless; IgG, immunoglobulin G; WB, western blot; IP, immunoprecipitation; GSI, g-secretase inhibitor; MDS, myelodysplastic syndrome; LPE, low protein expression; SNV, single nucleotide variant; CNA, copy number alteration; NGS, next generation sequencing; ddPCR, droplet digital polymerase chain reaction; AML, acute myeloid leukemia; CHD, clonal hematopoietic disorder.