Fechtner综合征的非肌性肌球蛋白重链ⅡA的表达与功能研究

本研究探讨对非肌性肌球蛋白ⅡA的表达和功能，以阐明MYH9综合征肾脏病变和中性粒细胞包涵体形成的机制。采用半定量Westem—blot检测中性粒细胞非肌性肌球蛋白ⅡA的表达；以胚肾细胞（HEK-293）为研究对象对ⅡA、ⅡB之间的相互作用进行了探讨；RT-PCR法检测HEK-293细胞中非肌性肌球蛋白ⅡA、ⅡB的表达，并对其进行了免疫共沉淀的研究。结果显示：先证者中性粒细胞ⅡA／β-actin比值为（0.35±0．12），较正常对照中性粒细胞ⅡA／β-actin的比值（0．87±0．18）明显减少（P〈0．01）。非肌性肌球蛋白ⅡA、非肌性肌球蛋白ⅡB在HEK-293细胞中均有较高的表达；免疫共沉淀分析表明，非肌性肌球蛋白ⅡA和非肌性肌球蛋白ⅡB均有表达，而阴性对照两者均无表达。结论：非肌性肌球蛋白ⅡA的负显性效应导致了中性粒细胞包涵体的产生。ⅡA和ⅡB有明显的相互作用，ⅡB至少是部分补偿了Fechtner综合征突变的ⅡA蛋白的作用并延缓了组织的功能障碍。

Expression and Function of Non-muscle Myosin-IIA in Fechtner Syndrome

The study was purposed to investigate the expression and function of non-muscle myosin heavy chain-IIA (NMMHC-IIA) in Fechtner syndrome in order to explore the pathologic changes of kindy disease and the mechanism of granulocyte inclusion body formation. NMMHC-IIA levels in granulocytes were analyzed by Western-blot, the expressions of NMMHC-IIA, IIB in HEK-293 cells were detected by RT-PCR and were analyzed by co-immunoprecipatation. The results indicated that the IIA/beta-actin ratio for Fechtner syndrome granulocytes was (0.35 +/- 0.12), and obviously decresed as compared with that of normal control (0.87 +/- 0.18) (p < 0.01). The IIA and IIB expressed higher in HEK-293 cells. The interaction of IIA and IIB was confirmed by co-immunoprecipation in HEK-293 cells. It is concluded that dominant-negative effect of NMMHC-IIA is involved in the formation of inclusion bodies. IIA and IIB show obvious interaction, IIB partly compensates the IIA defect derived from MYH9 mutations, and may delay or prevent the development of clinically relevant abnormalities.