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Exp Hematol. 2015 Jan;43(1):53-64.e1-8. doi: 10.1016/j.exphem.2014.09.004. Epub 2014 Sep 20.

Sall4 overexpression blocks murine hematopoiesis in a dose-dependent manner.

Author information

1
Sanford Children's Health and Cancer Biology Research Centers, Sioux Falls, SD, USA; Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, USA. Electronic address: samuel.milanovich@sanfordhealth.org.
2
Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, USA.
3
Medical College of Wisconsin, Milwaukee, WI, USA.
4
Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA.
5
Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Division of Pediatric Hematology, Oncology, and Blood and Marrow Transplant, Medical College of Wisconsin, Milwaukee, WI, USA.

Abstract

Sal-like protein 4 (SALL4) is a transcription factor that exists in two splice isoforms, SALL4a and SALL4b, and regulates transcription in embryonic stem cells, hematopoiesis, and acute myeloid leukemia. Constitutive overexpression of SALL4 in mice induces acute myeloid leukemia. Interestingly, a potential benefit of using SALL4 to facilitate ex vivo hematopoietic stem cell expansion has been proposed. However, distinct roles for how SALL4 contributes to normal versus malignant processes remain undefined. Here we show that SALL4b is the predominant isoform in murine hematopoietic stem cells and progenitors. Overexpression of either SALL4 isoform in hematopoietic stem cells or progenitors impairs hematopoietic colony formation and expansion in vitro. Lineage-negative bone marrow overexpressing SALL4b fails to engraft and reconstitute hematopoiesis when transplanted. We found that both SALL4a and SALL4b overexpression impair hematopoiesis, in part through dose-dependent repression of BMI1. Additionally, we have identified the following potential novel SALL4 target genes in hematopoiesis: ARID5B (SALL4a and SALL4b), EZH2, and KLF2 (SALL4a). Lastly, we found that SALL4 expression is variable in acute myeloid leukemia, ranging from no expression to levels comparable to embryonic stem cells. These results show that SALL4 isoforms contribute to only a subset of acute myeloid leukemia and that overexpression of SALL4 isoforms impairs hematopoiesis through repression of BMI1. Together these data demonstrate the sensitivity of hematopoiesis to appropriately balanced SALL4 expression, highlighting the importance of regulating this dynamic in potential therapeutic applications such as ex vivo stem cell expansion.

PMID:
25246269
PMCID:
PMC4268405
DOI:
10.1016/j.exphem.2014.09.004
[Indexed for MEDLINE]
Free PMC Article

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