Enhanced self-renewal of hematopoietic stem/progenitor cells mediated by the stem cell gene Sall4

Abstract

BackgroundSall4 is a key factor for the maintenance of pluripotency and self-renewal of embryonic stem cells (ESCs). Our previous studies have shown that Sall4 is a robust stimulator for human hematopoietic stem and progenitor cell (HSC/HPC) expansion. The purpose of the current study is to further evaluate how Sall4 may affect HSC/HPC activities in a murine system.MethodsLentiviral vectors expressing Sall4A or Sall4B isoform were used to transduce mouse bone marrow Lin-/Sca1+/c-Kit+ (LSK) cells and HSC/HPC self-renewal and differentiation were evaluated.ResultsForced expression of Sall4 isoforms led to sustained ex vivo proliferation of LSK cells. In addition, Sall4 expanded HSC/HPCs exhibited increased in vivo repopulating abilities after bone marrow transplantation. These activities were associated with dramatic upregulation of multiple HSC/HPC regulatory genes including HoxB4, Notch1, Bmi1, Runx1, Meis1 and Nf-ya. Consistently, downregulation of endogenous Sall4 expression led to reduced LSK cell proliferation and accelerated cell differentiation. Moreover, in myeloid progenitor cells (32D), overexpression of Sall4 isoforms inhibited granulocytic differentiation and permitted expansion of undifferentiated cells with defined cytokines, consistent with the known functions of Sall4 in the ES cell system.ConclusionSall4 is a potent regulator for HSC/HPC self-renewal, likely by increasing self-renewal activity and inhibiting differentiation. Our work provides further support that Sall4 manipulation may be a new model for expanding clinically transplantable stem cells.

The Short Isoform of NF‐YA Belongs to the Embryonic Stem Cell Transcription Factor Circuitry

“…Finally, we notice a good parallel between NF-YAs and SALL4, another TF important for ESCs [3,40,41], shown to have effects similar to NF-YA on HSCs, including after protein transfections [40,42]. SALL4 is also present in two isoforms, and one is specifically important in ESCs as part of the stem TF circuitry [43], which involves co-occupation of NANOG sites [44].…”

CAPE promotes the expansion of human umbilical cord blood-derived hematopoietic stem and progenitor cells in vitro

“…Several labs explored to expand HSPCs with aryl hydrocarbon receptors, copper chelators, stromal support, and automated continuous perfusion of culture systems or "bioreactors" [3,68]. Over-expression of transcription factors, such as SALL4, HOXB4, can also increase the number of HSPCs in vitro [9,10]. Although in vitro culture method for expansion of HSPCs has been improved, it still needs to be optimized to obtain more transplantable HSPCs.…”

Stem Cell Gene SALL4 Suppresses Transcription through Recruitment of DNA Methyltransferases

“…Isolation of Murine Hematopoietic Stem/Progenitor CellsMouse bone marrow hematopoietic stem/progenitor cells (Lin Ϫ /Sca-1 ϩ /c-Kit ϩ , LSK cells) were purified from 8 -12-week-old C57Bl/6J mice as described previously (13).…”

“…Lentiviral Transduction and qRT-PCT Assays-Detailed transduction procedures for mouse bone marrow LSK cells were described previously (13). For NB4 cell transduction, SALL4 lentivirus particles at a multiplicity of infection of 10 or 20 were added to the cells at 37°C.…”

“…In embryonic stem cells, SALL4 can activate OCT4 and interact with Nanog, and the SALL4/OCT4/Nanog transcriptional network is essential for the maintenance of cell "stemness" (9 -11). Recently, we have shown that SALL4 can serve as a robust stimulator for the expansion of hematopoietic stem/progenitor cells (12,13). The mechanisms by which SALL4 affects hematopoietic stem/progenitor cell growth and identity include blocking differentiation and permitting proliferation of undifferentiated cells (12,13).…”