Involving of the cytoplasmic region of leukemia inhibitory factor receptor alpha subunit, IL-6 related signal transducer-gp130 or fas death domain for MAPK p42/44 activation in HL-60 cell with LIF or anti-Fas IgG.

The chimeric receptors were prepared by exchanging the cytoplasmic region between leukemia inhibitory factor (LIF) receptor alpha subunit (gp190) and the other subunit-gp130 (190/130,130/190) and separately transduced into leukemia line HL-60 (to have the wild type subunit). The purpose is to investigate which subunit for activating MAPK p42/44 in leukemia cell while the cytoplasmic region homodimerization (190cyt-190cyt, 130cyt-130cyt) was induced by LIF. The results showed that MAPK p42/44 expression level after LIF stimulation 5 h was lower in the transformants with pED 130/190 (190cyt- 190cyt) (p < 0.01) and higher in the transformants with pED 190/130 (130cyt- 130cyt) (p < 0.05) than those in the parent cells. Meanwhile, MAPK p42/44 phosphorylation (Thr202/Tyr204) was ascended and the highest at 10 min in the 190/130 and descended in the 130/190. It suggests that gp130 activate MAPK p42/44 and gp190 indirectly regulate its expression and function. In order to analyses the relation of the subunit oligomerization and MAPK p42/44 we also prepared the recombination of the extracellular and transmembrane region of Fas and the cytoplasmic region of each LIFR subunit (Fas/190, Fas/130). After transduction into HL-60 with lipofection and induction by anti-Fas IgG, we found that MAPK p42/44 expression levels were lower in the Fas/190 than in the Fas/130 and parent cells (p < 0.01) and no difference between the Fas/130 and the wild type receptor. However, phospho-MAPK p42/44 were increased in the Fas/130 than the parent cells. It suggests that the oligomerization of the cytoplasmic regions of gp130 be potential to normally initiate MAPK p42/44 for the signal of HL-60 proliferation. We also determine that the separated oligomerization FasDD (no dimerization) can initiate the corresponding signal molecules, then regulate MAPK p42/44 expression and phosphorylation in leukemia cells.