| With RT-PCR technique, a 909bp fragment comprising the extracelluler D I, II, III portion of human M-CSF-R, was obtained from human placenta total RNA. Sequence analysis showed that it had the same sequence as that previously reported. After inserted into the E coli. expression vector pGEX-4T-2, transfromed into BL21 and induced with IPTG, a new protein band of about 67kD was observed by SDS-PAGE. The partially purified product could inhibit up to 79.6% colony fromation of J6-1 cells in semi-solid culture, and this inhibitory activity could be neutralized by anti-M-CSF-R monoclonal antibody. The growth of human hepatoma cells, SMMC 7721, and human leukemia cells, HL60, could also be inhibited by the partically purified product in a time- and dose-dependment manner. It suggested that the expression product of the cloned gene fragment of M-CSF-R appeared binding activity of M-CSF receptor.We have noticed that the level of M-CSF/M-CSF-R expression might relate to some abnormal hematopoiesis. In order to investigate the role of cyto-M-CSF/M-CSF-R in pathologic hematopoiesis of leukemia, 12 peripheral blood samples from normal donors, 21 bone marrow samples from clinic patients and 6 hematogenous cell lines were assayed for the mRNA and protein of M-CSF/M-CSF-R using RT-PCR and ABC-immunoperoxidase assay. It was indicated that: 1. the mononuclear cells unstimulated with PHA were M-CSF/M-CSF-R negetive and were positive diversaly after stimulation with PHA; 2. in contrast to the normals, hematopoietic cells from clinic patients unstimulated with PHA were M-CSF/M-CSF-R positive. ABC-assay revealed that M-CSF/M-CSF-R were distributed in membrane, plasma and nuclear of the patient's cells. High expression level of M-CSF/M-CSF-R were also found in the 6 cell lines, specially in HL60, the M-CSF/M-CSF-R were mainly located in the nuclear. The results above suggested that the expression and distribution of M-CSF/M-CSF-R were heterogenesis in malignent hematopoiesis.
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