| Objective: Aplastic anemia (AA) which is characterized by bone marrowfailture resulting in pancytopenia is a common disease and very harmful to children's health.Although the aberrant immune response and the destruction of the hematopoietic stem cells and bone marrow hematopoitic micro-enviroment might cause the disease,the clear mechanism of it hasn't been known.Many experiments using the techonology of hematopoitic cell colony formation have shown that the bone marrow hematopioetic stem cells or progenitor cells of aplastic anemia were lower than the normal control,suggesting the the destruction of the hematopoietic is the main reason of the disease.The lastest study shows that the the fuction of bone marrow is regulated by some cytokines and their receptors.These factors combine with their recepor to regulate proliferation, differentiation,apoptosis through multiple signal transduction path way or inacting some genes.After the stem cell factor and its receptor(C-KIT) were found,people instantly associated them with the aplastic anemia. Though many hematologic diseases have been reported in recent years ,few studies were focused on the relationship between AA and the receptor of the stem cell. C-KIT plays an important roles in gametogenesis, hematopoiesis, mast cell development and function, and melanogenes. Recently,the investigators found the complete absence of stem cell factor or Kit is lethal,meanwhile, gain-of-function mutations of C-KIT are associated with several human neoplasms including acute myelogenous leukemia, gastrointestinal stromal tumors, mastocytomas, and nasal T-cell lymphomas. In order to know the relationship between C-KIT and AA, We studied the mRNA expression and structure mutations of stem cell factor receptor gene (C-KIT gene) exon 9,11,13 in the children with aplastic amemia .Materials And Methods: The 15 cases of children with aplastic anemiawere selected as study group and 15 children with non-hematopoietic disease were selected as control group.The bone marrow of them were collected.Then the total RNA was extracted from the mononuclear cells seperated by density gradient centrifugal method and was reverse-transcripted into cDNA .According to the characteristics of the C-KIT gene structure, We designed three pairs primers of exons 9, 11, 13 of the C-KIT gene and ampilified them by means of polymerase chain reaction (PCR).The amplification products were electrophoresed on agarose gel ,the sample of expression positive were electrophoresed on polycrylamide gel and stained with stain silver nitrate.The products in gel were retrived and purified for futher sequence analysis to find the C-KIT gene exon struction difference between two group.Results:â‘ Using the RT-PCR and agarose gel ectrophorese method,themRNA expression positive rate of C-KIT exons 9, 11, 13 in.the children with aplastic anemia (40.00%) was not significantly higher than those of normal.(46.67%) (P>0.05) .â‘¡After electrophoresed on polycrylamide gel and stained with stain silver nitrate ,no mutations of the C-KIT gene exons 9, 11, 13 were found in these casesâ‘¢The sequence detection of those products showed the structures of the C-KIT gene exons 9,11, 13 have no abnormity.Conclusion : The C-KIT does not seem to be a necessary factor in the childwith aplastic anemia because neither expression nor activating mutations were found.The conclusion suggested the bone marrow failure of the children with AA may be related to the decrease of the expression of SCF protein,which play the main role in the singal pathway of the SCF/C-KIT.Then more attention should pay on it in the future.
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