Expression Of BAF-1in Thymus Of Myasthenia Gravis Patients

Background and objectiveMyasthenia gravis is an organ specific autoimmune disease characterized byfluctuating muscle weakness. So far, the pathogenesis of MG is still not fullyunderstood. The study found that70%-80%of MG patients has abnormal thymusincluding thymic hyperplasia and thymoma, therefore, the thymus becomes a hotspotof being sustained attention in MG research. At present, thymectomy is one of theeffective means of treatment of MG, therefore, it is possible that we explore therelationship between MG and abnormal thymus by resection of the thymus. Ourprevious study found that protein electrophoresis in thymus hyperplasia of MGpatients has the relative molecular mass of about11000difference (abnormal)bands,and the MG patients with positive bands are obviously superior to the negativepatients which are cut off the thymus by operation, so we speculate that the proteinbands are associated with the persist of the MG symptoms. Proteomic analysed11000bands, we found that BAF-1is an important protein component. Since the Barrier toautointegration factor1(BAF-1) exists in host components of retrovirus preintegration complex, and vitro experiments show that BAF-1participates in the process that integrates retrovirus mediated gene into the host target DNA. It also canbind the double stranded DNA,histone H3, the LEM domain of nuclear lamina andhomologous reverse transcription activator, and can directly affect nuclearreconstruction in mitosis anaphase. In order to further investigate the expression ofBAF-1in the thymus tissue of MG patients, analysis of biological function of BAF-1,and preliminary study the relationship with MG, we determined the relative contentof mRNA in BAF-1of the thymus by real-time quantitative PCR technique, and wealso verified BAF-1protein expression in the thymus tissue byimmunohistochemistry method.Methods1. Total RNA were extracted from hyperplasia type (9cases), atrophic type (12cases), thymoma type (10cases) and normal human thymus tissue (7cases) by trizol,and we determined the mRNA content of BAF-1by Real-time fluorescencequantitative PCR;2. Expression of BAF-1protein in the thymus tissue of proliferative, atrophictype, thymoma type and normal human is tissued by immunohistochemical analysis.Results1. BAF-1is Expressioned in MG group and normal thymus, and the expression of BAF-1in atrophy with normal human thymus and thymoma tissue and differences is statisticallysignificant (P=0.024<0.05, P=0.006<0.01), and the relative expression of atrophic thymusis higher than that of the normal thymus and thymoma tissue.2. Immunohistochemical staining showed that BAF-1has a possive expressionin proliferative, atrophic thymus and thymoma type of MG patients, but it is notobserved in normal thymus tissue. The differences of BAF-1protein expressionbetween the normal thymus and the other three groups are statistically significant (P<0.001), and the positive rate of BAF-1protein expressioned in normal thymic tissueis lower than the other three groups.Conclusion1.The expression differences of Protein BAF-1in the thymus tissue of MGpatients about mRNA and protein level indicate that may be related to the occurrenceof MG, especially atrophic thymus. 2.Protein BAF-1is a related protein of MG, is the material basis of thymicabnormalities, and lays a foundation for further study of MG.3. Expression of Protein BAF-1in the cortex of thymus, suggesting that it mayplay a role in thymocyte development.