Expression data from WT and BMPR2 knockout hematopoietic stem cells extracted from mice.. Expression data from WT and BMPR2 knockout hematopoietic stem cells extracted from mice.

Abstract copied in below, from Warsi et al. 2021 BMP signaling is required for postnatal murine hematopoietic stem cell self-renewal, published in Haematologica. DOI 10.3324/haematol.2019.236125 Life-long production of blood from hematopoietic stem cells (HSCs) is a process of strict modulation. Intrinsic and extrinsic signals govern fate options like self-renewal - a cardinal feature of HSCs. Bone morphogenetic proteins (BMP) have an established role in embryonic hematopoiesis, but less is known about its functions in adulthood. Previously, SMAD-mediated BMP signaling has been proven dispensable for HSCs. However, the BMP Type II receptor (BMPR-II) is highly expressed in HSCs, leaving the possibility that BMPs function via alternative pathways. Here, we establish that BMP signaling is required for self-renewal of adult HSCs. Through conditional knockout we show that BMPR-II deficient HSCs have impaired self-renewal and regenerative capacity. BMPR-II deficient cells have reduced p38 activation, implying that non-SMAD pathways operate downstream of BMPs in HSCs. Indeed, a majority of primitive hematopoietic cells do not engage in SMAD-mediated responses downstream of BMPs in vivo. Furthermore, deficiency of BMPR-II results in increased expression of TJP1, a known regulator of self-renewal in other stem cells, and knockdown of TJP1 in primitive hematopoietic cells partly rescues the BMPR-II null phenotype. This suggests TJP1 may be a universal stem cell regulator. In conclusion, BMP signaling, in part mediated through TJP1, is required endogenously by adult HSCs to maintain self-renewal capacity and proper resilience of the hematopoietic system during regeneration. Overall design: HSCs (LSK CD9hi CD48- CD150+) were sorted from c-kit enriched mouse bone marrow using FACS. Samples were frozen at -80 in RLT buffer and sent to KFB (Regenburg, Germany) for RNA extraction and hybridization on Affymetrix microarrays. Cells were sorted from fourBMPR2 knockout C57Bl/6 mice and four WT control mice (littermates). Please see further information in the associated pubilcation by Warsi et al. 2021.