Interleukin-3 and stem cell factor modulate cell cycle regulatory factors in mast cells: negative regulation of p27Kip1 in proliferation of mast cells induced by interleukin-3 but not stem cell factor.
OBJECTIVE
Interleukin-3 (IL-3) and stem cell factor (SCF) are able to promote survival and proliferation of mast cells. However, the precise signal transduction cascades leading to mast cell proliferation are not clearly understood. Thus, we sought to define the mechanism of mast cell proliferation induced by IL-3 and SCF.


METHODS
We treated murine bone marrow-derived cultured mast cells (BMCMC) with recombinant IL-3 (rIL-3) or recombinant SCF (rSCF) and examined the effects of rIL-3 and rSCF on cell cycle regulatory factors.


RESULTS
Both rIL-3 and rSCF suppressed apoptosis of BMCMC. rSCF induced great proliferation of BMCMC with elevation of the proportions of cells in S and G2/M phases, whereas most BMCMC incubated with rIL-3 were arrested in the G1 phase. The G1/S phase transition is initiated by phosphorylated retinoblastoma protein (pRb), which was prominent in cells stimulated with rSCF. In contrast, rIL-3 relatively increased a dephosphorylated form of pRb in BMCMC. Compared with rIL-3, rSCF induced greater expression of cyclin-dependent kinase (CDK) 2 and CDK4, which are able to phosphorylate pRb, and cyclin D3, a partner of CDK4. BMCMC treated with rIL-3 contained a high amount of a CDK inhibitor p27Kip1 that was suppressed by pretreatment with Ro31-7549, a protein kinase C inhibitor, whereas rSCF induced weak expression of p27Kip1 in BMCMC.


CONCLUSIONS
The results suggest that IL-3 and SCF exert their respective mitogenic effects on mast cells by modulating the expression of pRb, CDK, cyclin, and p27Kip1.
Itakura
A
A
Department of Veterinary Clinic, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Miura
Y
Y
Hikasa
Y
Y
Kiso
Y
Y
Matsuda
H
H
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects* / Q000502:physiology; D018797:Cell Cycle Proteins / Q000502:physiology; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27; D007377:Interleukin-3 / Q000494:pharmacology*; D008407:Mast Cells / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D019089:Stem Cell Factor / Q000494:pharmacology*; D025521:Tumor Suppressor Proteins
C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D007377:Interleukin-3; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27