H. Ishihara et al., IMMEDIATE-EARLY, TRANSIENT INDUCTION OF THE INTERLEUKIN-1-BETA GENE IN MOUSE SPLEEN MACROPHAGES BY IONIZING-RADIATION, Journal of radiation research, 36(2), 1995, pp. 112-124
In murine spleen cells, x ray irradiation induces the expression of th
e IL-1 beta gene at multiple phases of the peak time. We analyzed the
immediate-early phase of IL-1 beta mRNA accumulation. To determine the
lineage of cells that showed the immediate response to irradiation, n
ormal spleen cells were analyzed by Northern blotting and in situ hybr
idization after separation by magnetic antibodies against specific cel
l-surface antigens. Although mast of the spleen macrophages continuous
ly expressed a low level of IL-1 beta mRNA, a portion of the macrophag
e population transiently accumulated large amounts of IL-1 beta messag
e immediately after irradiation. A macrophage-like leukemia cell line
that resembles these inducible macrophages was identified. A similar i
mmediate-early and transient increase in the IL-1 beta mRNA level occu
rred when cultured spleen cells were irradiated with a low dose (3 Gy)
of x rays. In contrast, the x ray-inducible expression of the IL-1 be
ta gene was immediate and continuous, not transient, in spleen cells f
rom whole-body irradiated mice. Results of the run-on transcription as
say and the determination of the decrease in the message using culture
d spleen and macrophage-like leukemia cells indicated that x ray irrad
iation appears to activate the transcription of the IL-1 beta gene and
partially stabilize the message. The results show that the x ray-indu
ced immediate-early accumulation of IL-1 beta mRNA is regulated at bot
h the transcriptional and post-transcriptional levels in an as yet uni
dentified population of spleen macrophages.