Study On Mismatch Repair Gene PMS1in Marek’s Disease

Marek’s disease （MD）, caused by Marek’s disease virus （MDV）, is an acute lymphoproliferative disease in chicken’s. The lymphomagenesis of MDV has been studied in its pathology, virology, and immunology and diagnose on the early stage in molecular biology. Despite several decades of study, the pathogenesis for MD still needs to be elucidated. It has been confirmed that heredity nonpolysis colorectal cancer （HNPCC）, carcinoma of large intestine, gastric cancer, endometrial carcinoma and carcinoma of bile duct were caused by the failure of mismatch repair （MMR） system. Defects of mismatch repair genes have been reported to produce MSI in bacteria, yeast and human. This study will detect the variation of DNA and mRNA of PMS1in the tumor tissues of MDV-infected chicken, to analyse the MSI and expression difference of PMS1.Testl:Primer pairs were designed to amplify the MS locus found in PMS1with the software of SSRHunter. The tumor and normal tissues of22MDV-infected chicken ware analysed after PAGE, silver staining. One sample that the difference among tissues was significant was chosen for the sequencing to analyze the mutation of bases. Results; A new microsatellite locus,（GT）11, were found in the intron of PMS1（NC₀06094, NCBI） and primer pairs were designed to amplify the target fragment,203bp. Eventually, Microsatellite instability （MSI） was observed positively in16of22（72%） MDV-infected chicken. One sample of22, of which the MSI was obvious, was chosen for sequencing, the result revealed the replacement, mutation, insertion and deletion of bases in the new MS locus of tumor compared with the normal tissue from the same sample.Test2:Primer pairs were designed for the qPCR to detect the mRNA expression difference of9tissues （heart, liver, spleen, lung, kidney, blood, muscle, bursa of fabricius and bone marrow） from chicken of21-day-age and analyze the expression difference between normal and tumorigenic chicken. The statistical analysis results of qPCR:the expression of mRNA in different tissues differed from each other, the maximum in muscle and minimum in lung. The difference between muscle and heart, spleen were significant （P<0.05）, muscle and lung, blood extremely significant （P<0.01）. The expression of PMS1soared from tens to thousands times in heart, liver, lung and kidney form MDV-infected chicken, compared with normal chicken.According to the result of the study, a new MS locus was found in the intron of PMS1, increasing the diversity of microsatellite sites in chromosome of chicken. Moreover, the new MS locus may be used to detect the change of PMS1due that microsatellite instability happened to the new MS locus in tumor tissues.