c-kit ligand gene expression in normal and sublethally irradiated mice
A Limanni, WH Baker, CM Chang, R Seemann, DE Williams and ML Patchen
Dept of Experimental Hematology, Armed Forces Radiobiology Research
Institute, Bethesda, MD 20889-5603, USA.
The c-kit ligand (KL; Steel factor, mast cell growth factor, stem cell
factor) is a hematopoietic factor that has been shown to act as a potent
cofactor for hematopoietic growth and differentiation in vitro. The in vivo
effects of KL, however, have been variable. To study the hematopoietic role
of KL in vivo, we evaluated KL gene expression in both normal mice and mice
recovering from myelosuppressive radiation exposure using the reverse
transcriptase-polymerase chain reaction (RT- PCR) technique. In a single
RNA sample, we found that the RT-PCR technique has high precision
(co-efficient of variation, 15.7%). Amplifications of serial 1:2 dilutions
of template RNA precisely correlated with starting RNA concentrations at 20
cycles or at 25 cycles, depending on the level of expression. Amplification
of individual normal bone marrow and spleen cell RNA showed basal
expression in all normal bone marrows but irregular expression in normal
spleens. On day 2 after a sublethal 7.75-Gy (0.4 Gy/min) 60Co irradiation,
splenic KL gene expression increased approximately 2.5- fold (P = .011),
and bone marrow expression increased 15-fold (P = .004). During a 28-day
postirradiation recovery period, KL expression increased in bone marrow on
days 2 through 7. Splenic expression during the same period was more
variable. In conclusion, the KL gene is invariably expressed in normal
murine spleens. Postirradiation, recovering bone marrow and spleen both
express increased levels of KL mRNA at day 2 and continue to express
increased levels for several days postexposure. These data support a role
for KL in the endogenous recovery of hematopoiesis after hypoplastic
injury.
Volume 85,
Issue 9,
pp. 2377-2384,
05/01/1995
Copyright © 1995 by The American Society of Hematology
