The gene for erythropoietin receptor is expressed in multipotential hematopoietic and embryonal stem cells: evidence for differentiation stage-specific regulation.

Abstract

The principal regulator of erythropoiesis is the glycoprotein erythropoietin, which interacts with a specific cell surface receptor (EpoR). A study aimed at analyzing EpoR gene regulation has shown that both pluripotent embryonal stem cells and early multipotent hematopoietic cells express EpoR transcripts. Commitment to nonerythroid lineages (e.g., macrophage or lymphocytic) results in the shutdown of EpoR gene expression, whereas commitment to the erythroid lineage is concurrent with or followed by dramatic increases in EpoR transcription. To determine whether gene activity could be correlated with chromatin alterations, DNase-hypersensitive sites (HSS) were mapped. Two major HSS located in the promoter region and within the first intron of the EpoR gene are present in all embryonal stem and hematopoietic cells tested, the intensities of which correlate well with EpoR expression levels. In addition, a third major HSS also located within the first intron of the EpoR gene is uniquely present in erythroid cells that express high levels of EpoR. Transfection assays show that sequences surrounding this major HSS impart erythroid cell-specific enhancer activity to a heterologous promoter and that this activity is at least in part mediated by GATA-1. These data, together with concordant expression levels of GATA-1 and EpoR in both early multipotent hematopoietic and committed erythroid cells, support a regulatory role of the erythroid cell-specific transcription factor GATA-1 in EpoR transcription in these cells. However, the lack of significant levels of GATA-1 expression in embryonal stem cells implies an alternative regulatory mechanism of EpoR transcription in cells not committed to the hematopoietic lineage.

Development of primitive and definitive hematopoiesis from nonhuman primate embryonic stem cells in vitro

“…This result is consistent with reports showing that murine primitive and definitive erythrocytes have different requirements for EPO Lin et al, 1996). As previously reported in murine ES cells (Heberlein et al, 1992;Keller et al, 1993), the EPOR is expressed in undifferentiated primate ES cells. However, it is unlikely that erythrocytes are contained in undifferentiated ES cells, because no globin gene expression is detected before the induction of differentiation.…”

Localization of specific erythropoietin binding sites in defined areas of the mouse brain.

“…Nomenclature (29) (17) suggests that axons might be one possible candidate carrying the EPO-R. Furthermore, expression of EPO-R reported in mouse embryonic stem cells (30) and in the mouse postimplantation embryo (31) has interesting implications for the role of EPO in early development, including hematopoiesis and neurogenesis. This notion is further supported by a report describing the tissue-specific mRNA expression of the endogenous EPO-R gene and the human EPO-R transgene in the brain of transgenic mouse embryos (32).…”

Erythroid-specific expression of the erythropoietin receptor rescued its null mutant mice from lethality

“…Although EpoR expression has been demonstrated in hematopoietic stem cells and progenitors of the bone marrow, 23 we envisage that expression of the HG1-EpoR transgene cannot recapitulate EpoR expression in such cells. To address the question as to whether EpoR is indispensable for the differentiation and maintenance of stem cells and progenitors, we performed FACS and RT-PCR analyses of Rescued-A mice containing Tg-A and HG1-GFP transgenes.…”

“…Kernechtrot solution was used for counterstaining in all sections. [17][18][19][20][21][22][23][24], and Rescued-B (lanes 25-32) mice were analyzed. PCR was performed using primer sets Primer 1 with 2 and Primer 3 with 2 to detect endogenous (600 bp) and transgenic (701 bp) EpoR transcripts, respectively.…”