Abstract
The EML hematopoietic progenitor cell line is a model system for studying molecular events regulating myeloid commitment and terminal differentiation. We used representational difference analysis to identify genes that are expressed differentially during myeloid differentiation of EML cells. One gene (named mAKRa) encoded a novel member of the aldoketo reductase (AKR) superfamily of cytosolic NAD(P)(H)-dependent oxidoreductases. mAKRa mRNA was detected in murine hematopoietic tissues including bone marrow, spleen, and thymus. In myeloid cell lines, mAKRa was expressed at highest levels in cells representative of promyelocytes. mAKRa mRNA levels increased rapidly in response to interleukin-3 over the first 24 h of EML cell differentiation when the cells undergo lineage commitment and extensive proliferation. mAKRa mRNA levels decreased later in the differentiation process particularly when the EML cells were cultured with granulocyte/macrophage colony-stimulating factor and retinoic acid to induce terminal granulocytic maturation. mAKRa mRNA levels decreased during retinoic acid-induced terminal granulocytic differentiation of the MPRO promyelocyte cell line. AKRs act as molecular switches by catalyzing the interconversion or inactivation of bioactive molecules including steroids and prostaglandins. We propose that mAKRa may catalyze the production or catabolism of autocrine factors that promote the proliferation and/or lineage commitment of early myeloid progenitors.
Highlights
The EML hematopoietic progenitor cell line is a model system for studying molecular events regulating myeloid commitment and terminal differentiation
Because the EML differentiation protocol used to isolate mouse aldoketo reductase a (mAKRa) causes differentiation along the myeloid lineage, we examined mAKRa expression in hematopoietic cell lines to test whether it is expressed in a lineage- or stage-specific manner
Factor-dependent Regulation of mAKRa Expression—Having shown that the decrease in mAKRa mRNA levels during terminal granulocytic maturation appears to be dependent on all-trans-retinoic acid (atRA), we examined lastly whether the initial increase in mAKRa mRNA levels during myeloid differentiation in EML cells was dependent on atRA or IL-3
Summary
Vol 275, No 10, Issue of March 10, pp. 6724 –6732, 2000 Printed in U.S.A. Identification of an Interleukin-3-regulated Aldoketo Reductase Gene in Myeloid Cells Which May Function in Autocrine Regulation of Myelopoiesis*. This block can be overcome by culturing in the presence of the multifunctional cytokine interleukin-3 (IL-3) and pharmacological doses of all-trans-retinoic acid (atRA) [17, 22] Under these conditions, EML cells differentiate into promyelocytes over a period of 6 –7 days, and differentiation-specific genes are expressed in patterns similar to those seen in bona fide hematopoietic progenitors [17, 24, 25]. In this study we sought to identify genes that are activated during the initial stages of myeloid differentiation by using RDA to isolate genes whose expression is elevated 72 h after the addition of IL-3 and atRA to the EML culture This time point was chosen because many cells have become committed to the myeloid lineage at this stage, as measured by their responsiveness to GM-CSF [17], few cells have reached terminal maturation [25]. Based on its expression pattern in EML and MPRO cells, and the ability of AKRs to metabolize molecules such as prostaglandins and steroids, we propose that it may function in the synthesis or catabolism of autocrine/intracrine factors that regulate myeloid differentiation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
