TY - JOUR
T1 - Runx1 isoforms show differential expression patterns during hematopoietic development but have similar functional effects in adult hematopoietic stem cells
AU - Challen, Grant A.
AU - Goodell, Margaret A.
N1 - Funding Information:
The authors would like to thank all members of the Goodell Laboratory for scientific advice, and Chris Threeton for flow cytometric sorting and analysis. G.A.C. was supported by an Australian National Health and Medical Research Council CJ Martin Fellowship (Melbourne, Victoria, Australia). This work was also supported by National Institutes of Health (Bethesda, MD, USA) grants HL081007 , EB005173 , DK075355 , and DK58192 .
PY - 2010/5
Y1 - 2010/5
N2 - Objective: RUNX1 (also known as acute myeloid leukemia 1) is an essential regulator of hematopoiesis and has multiple isoforms arising from differential splicing and utilization of two promoters. We hypothesized that the rare Runx1c isoform has a distinct role in hematopoietic stem cells (HSCs). Materials and Methods: We have characterized the expression pattern of Runx1c in mouse embryos and human embryonic stem cell (hESC)-derived embryoid bodies using in situ hybridization and expression levels in mouse and human HSCs by real-time polymerase chain reaction. We then determined the functional effects of Runx1c using enforced retroviral overexpression in mouse HSCs. Results: We observed differential expression profiles of RUNX1 isoforms during hematopoietic differentiation of hESCs. The RUNX1a and RUNX1b isoforms were expressed consistently throughout hematopoietic differentiation, whereas the RUNX1c isoform was only expressed at the time of emergence of definitive HSCs. RUNX1c was also expressed in the AGM region of E10.5 to E11.5 mouse embryos, the region where definitive HSCs arise. These observations suggested that the RUNX1c isoform may be important for the specification or function of definitive HSCs. However, using retroviral overexpression to study the effect of RUNX1 isoforms on HSCs in a gain-of-function system, no discernable functional difference could be identified between RUNX1 isoforms in mouse HSCs. Overexpression of both RUNX1b and RUNX1c induced quiescence in mouse HSCs in vitro and in vivo. Conclusions: Although the divergent expression profiles of Runx1 isoforms during development suggest specific roles for these proteins at different stages of HSC maturation, we could not detect an important functional distinction in adult mouse HSCs using our assay systems.
AB - Objective: RUNX1 (also known as acute myeloid leukemia 1) is an essential regulator of hematopoiesis and has multiple isoforms arising from differential splicing and utilization of two promoters. We hypothesized that the rare Runx1c isoform has a distinct role in hematopoietic stem cells (HSCs). Materials and Methods: We have characterized the expression pattern of Runx1c in mouse embryos and human embryonic stem cell (hESC)-derived embryoid bodies using in situ hybridization and expression levels in mouse and human HSCs by real-time polymerase chain reaction. We then determined the functional effects of Runx1c using enforced retroviral overexpression in mouse HSCs. Results: We observed differential expression profiles of RUNX1 isoforms during hematopoietic differentiation of hESCs. The RUNX1a and RUNX1b isoforms were expressed consistently throughout hematopoietic differentiation, whereas the RUNX1c isoform was only expressed at the time of emergence of definitive HSCs. RUNX1c was also expressed in the AGM region of E10.5 to E11.5 mouse embryos, the region where definitive HSCs arise. These observations suggested that the RUNX1c isoform may be important for the specification or function of definitive HSCs. However, using retroviral overexpression to study the effect of RUNX1 isoforms on HSCs in a gain-of-function system, no discernable functional difference could be identified between RUNX1 isoforms in mouse HSCs. Overexpression of both RUNX1b and RUNX1c induced quiescence in mouse HSCs in vitro and in vivo. Conclusions: Although the divergent expression profiles of Runx1 isoforms during development suggest specific roles for these proteins at different stages of HSC maturation, we could not detect an important functional distinction in adult mouse HSCs using our assay systems.
UR - http://www.scopus.com/inward/record.url?scp=77951459994&partnerID=8YFLogxK
U2 - 10.1016/j.exphem.2010.02.011
DO - 10.1016/j.exphem.2010.02.011
M3 - Article
C2 - 20206228
AN - SCOPUS:77951459994
SN - 0301-472X
VL - 38
SP - 403
EP - 416
JO - Experimental Hematology
JF - Experimental Hematology
IS - 5
ER -