| Research Abstract |
1. The proto-oncogene c-kit encodes a transmembrane tyrosine kinase receptor for stem cell factor (SCF). A monoclonal antibody against the murine c-kit molecule was prepared. Eight and 25 weeks after transplantation of Lin^-c-kit^+ cells, donor-derived cells were found in the bone marrow, spleen, thymus and peripheral blood. These data show that the c-kit molecule is expressed in multipotent stem cells and plays an essential role in the early stage of hematopoiesis.
Based on these findings, we were able to purify the murine stem cells (CFU-S).
2. To characterize and clarify the function of CD34 antigen, we isolated two types of CD34 mRNA which were generated by alternative splicing. The cDNA sequence predicted a 382 amino acid protein containing an N-terminal signal peptide and one transmembrane region 73 aminoacids from the c-terminus. Northern blot analysis using a murine cDNA probe showed that CD34 was highly expressed in the brain and testis, and moderately in the thymus, spleen and bone marrow, but not in adult liver. However, day 12 to 14 fetal liver cells showed significant expression of CD34.
3. We have cloned genomic CD34 and have a plan to examine the promoter and enhancer region. To clarify the function of CD34 molecule, we are now preparing the transgenic mice of CD34. Moreover, we are constructing the Lac Z-CD34 gene to Knock out genomic CD34. and
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