Human interleukin-3 mRNA accumulation is controlled at both the
transcriptional and posttranscriptional level
GR Ryan, SE Milton, AF Lopez, PG Bardy, MA Vadas and MF Shannon
Institute of Medical and Veterinary Science, Adelaide, South Australia.
Interleukin-3 (IL-3) is a hematopoietic growth factor that regulates the
differentiation of multilineage and committed progenitor cells and the
functions of some mature blood cells. The expression of human IL-3 appears
to be restricted to stimulated T lymphocytes. We have investigated the
kinetics and mechanisms involved in the induction of IL-3 expression in the
human T lymphocytic tumor cell line Jurkat. We show that accumulation of
IL-3 mRNA is controlled at both the transcriptional and posttranscriptional
level. Transcription of the IL- 3 gene in these cells appears to be
constitutive but no IL-3 mRNA was detected in unstimulated cells,
indicating that in resting cells IL-3 mRNA is highly unstable. Treatment
with phytohemagglutinin (PHA) induced a small and transient increase in the
IL-3 gene transcription rate and led to the production of detectable levels
of IL-3 mRNA and protein. Optimal induction of IL-3 expression required a
second stimulus. Costimulation of Jurkat cells with both phorbol myristate
acetate and PHA caused both a transient increase in IL-3 gene
transcription, which is dependent on new protein synthesis, and also a
transient increase in mRNA stability.
Volume 77,
Issue 6,
pp. 1195-1202,
03/15/1991
Copyright © 1991 by The American Society of Hematology
