| |
|
|
|
|
|
|
|||
|
DJ Park, RW Lim and HD Kim
Department of Pharmacology, University of Missouri-Columbia, School of
Medicine, Columbia 65212.
We examined the activation of genes induced by erythropoietin (Epo) in
erythroid progenitor cells that were isolated from the spleens of mice
infected with anemia-inducing strain of the Friend virus. These erythroid
progenitor cells, termed FVA cells, undergo in vitro differentiation to
erythrocytes under the influence of Epo within 2 to 3 days. We used a
differential hybridization procedure to screen a cDNA library constructed
from FVA cells that were treated with Epo 2U/mL in the absence of serum for
2 hours. Of 20,000 recombinant phages, 47 plaques hybridized preferentially
to cDNA probe prepared from Epo- stimulated cells. We found at least three
different Epo-responsive genes (ERGs) and one of them corresponds to the
mouse virus-like (VL30) element, similar to already reported BVL-1. The
induction of VL30, which was evident within 30 minutes after Epo exposure,
reached a maximum by 1 hour and remained stable for up to 4 hours. The
treatment of FVA cells with cycloheximide (CHX) 10 micrograms/mL, which in
itself activates the expression of VL30 caused a superinduction of the Epo
signal. Changes in intracellular Ca2+ concentrations, either raised by
ionomycin or depleted by EGTA, had no effect on the Epo-induced VL30
expression. In addition, protein kinase C (PKC) inhibitors such as
staurosporine (3 mumol/L) or H7 (20 mumol/L) and a tyrosine kinase
inhibitor, genistein (200 mumol/L), did not inhibit the Epo-induced
expression of VL30. TPA (100 ng/mL), a PKC agonist, did not induce VL30
expression. Although the physiologic role of VL30 in the differentiation of
erythroid progenitor cells is not known, our findings demonstrate that VL30
is an early ERG, and may be a useful indicator of the initial molecular
actions of Epo.
This article has been cited by other articles:
| |||||||||||
| Copyright © 1993 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||