Smarca5 (Snf2h) is required for Proliferation of Hematopoietic Stem Cells Differentiating into Erythroid and Myeloid lineages

The Imitation Switch (ISWI) nuclear ATPase Smarca5 (Snf2h) is one of the most conserved chromatin remodeling factors. It exists in a variety of oligosubunit complexes that move DNA with respect to the histone octamer to generate regularly spaced nucleosomal arrays. Smarca5 interacts with different accessory proteins and represents a molecular motor for DNA replication, repair and transcription. We deleted Smarca5 at the onset of definitive hematopoiesis (Vav1-iCre) and observed that animals die during late fetal development due to anemia. Hematopoietic stem and progenitor cells (HSPCs) accumulated but their maturation towards erythroid and myeloid lineages was inhibited. Proerythroblasts were dysplastic while basophilic erythroblasts were blocked in G2/M and depleted. Smarca5 deficiency led to increased p53 levels, its activation at two residues, one associated with DNA damage (S18) second with CBP/p300 (K382), and finally activation of the p53 targets. We also deleted Smarca5 in committed erythroid cells (Epor-iCre) and observed that animals were anemic postnatally. Furthermore, 4-OHT-mediated deletion of Smarca5 in the ex vivo cultures confirmed its requirement for erythroid cell proliferation. Thus, Smarca5 plays indispensable roles during early hematopoiesis and erythropoiesis. STEM CELLS 2017; 00:000–000 SIGNIFICANCE STATEMENT: ISWI chromatin remodeling ATPase Smarca5 is a highly conserved chromatin-remodeling factor that is expressed in hematopoietic tissues especially stem and progenitor cells. There exist several oligosubunit complexes containing Smarca5 as a catalytic subunit that were previously shown to actively regulate nucleosomal structure and position during DNA replication, repair and transcription. Genetic inactivation of Smarca5 specifically in murine definitive hematopoietic cells leads to the developmental blockade marked by unique proliferative defects such as tetraploidy and erythroid dysplasia. The Smarca5 gene is not mutated in cancer, however its expression is enhanced in acute myeloid leukemia and aggressive solid tumors. This may be exploited for development of future therapies for targeting the growth and repopulation of human malignancies.

[1]  Xiao-Peng Zhang,et al.  Modeling the interplay between the HIF-1 and p53 pathways in hypoxia , 2015, Scientific Reports.

[2]  W. Kloosterman,et al.  Chromosomal instability, tolerance of mitotic errors and multidrug resistance are promoted by tetraploidization in human cells , 2015, Cell cycle.

[3]  T. Zikmund,et al.  Epigenetic Control of SPI1 Gene by CTCF and ISWI ATPase SMARCA5 , 2014, PloS one.

[4]  S. Morrison,et al.  SLAM family markers resolve functionally distinct subpopulations of hematopoietic stem cells and multipotent progenitors. , 2013, Cell stem cell.

[5]  K. Rippe,et al.  Chromatin remodelling in mammalian cells by ISWI‐type complexes – where, when and why? , 2011, The FEBS journal.

[6]  Y. Liu,et al.  A Key Commitment Step in Erythropoiesis Is Synchronized with the Cell Cycle Clock through Mutual Inhibition between PU.1 and S-Phase Progression , 2010, PLoS biology.

[7]  R. Kingston,et al.  Diverse regulation of SNF2h chromatin remodeling by noncatalytic subunits. , 2008, Biochemistry.

[8]  M. Weiss,et al.  Repression of c-Kit and Its Downstream Substrates by GATA-1 Inhibits Cell Proliferation during Erythroid Maturation , 2005, Molecular and Cellular Biology.

[9]  S. Morrison,et al.  Supplemental Experimental Procedures , 2022 .

[10]  P. Vyas,et al.  GATA-1 forms distinct activating and repressive complexes in erythroid cells , 2004 .

[11]  U. Klingmüller,et al.  A mouse model for visualization and conditional mutations in the erythroid lineage. , 2004, Blood.

[12]  A. Skoultchi,et al.  The ISWI ATPase Snf2h is required for early mouse development , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Mark Coles,et al.  Transgenic mice with hematopoietic and lymphoid specific expression of Cre , 2003, European journal of immunology.

[14]  R. Margolis,et al.  Tetraploid state induces p53-dependent arrest of nontransformed mammalian cells in G1. , 2001, Molecular biology of the cell.

[15]  Shankar Srinivas,et al.  Cre reporter strains produced by targeted insertion of EYFP and ECFP into the ROSA26 locus , 2001, BMC Developmental Biology.

[16]  J. Jelinek,et al.  Chromatin remodeling gene SMARCA5 is dysregulated in primitive hematopoietic cells of acute leukemia , 2000, Leukemia.

[17]  B. Emerson,et al.  A SWI/SNF–Related Chromatin Remodeling Complex, E-RC1, Is Required for Tissue-Specific Transcriptional Regulation by EKLF In Vitro , 1998, Cell.

[18]  P. Carmeliet,et al.  Role of HIF-1 alpha in hypoxia-mediated apoptosis, cell proliferation and tumour angiogenesis (vol 394, pg 485, 1998) , 1998 .

[19]  K. Sakaguchi,et al.  DNA damage activates p53 through a phosphorylation-acetylation cascade. , 1998, Genes & development.

[20]  Rudolf Jaenisch,et al.  Generation of committed erythroid BFU-E and CFU-E progenitors does not require erythropoietin or the erythropoietin receptor , 1995, Cell.

[21]  H. Beug,et al.  Expansion and differentiation of immature mouse and human hematopoietic progenitors. , 2005, Methods in molecular medicine.