Study On Related Genes Associated With Early Phase Of Experimental Brain Abscess By MRNA Differential Display PCR

ObjectiveTo search the related genes associated with early phase of experimental brain abscess and to explore the molecular mechanism of brain abscess.MethodBrain abscesses were produced in the rat by direct intracerebral injection of stapbylococcus aureus. In early phase of experimental brain abscess, abscess tissue samples were compared with normal and control group by mRNA differential display PCR. Differentially expressed cDNA fragments were cloned into the pGEM-Teasy vector. Positive clones were sequenced and then confirmed by Northern blot or RT-PCR. All the sequences were put into Genebank database and analyzed by BLASTN software to search for their genetics origins or to find novel genes. Then novel genes were submitted to Genebank database. Chromosome location and electronic cloning were performed by bioinformatics. The sequences obtained from electronic cloning were confirmed by RT-PCR and predicted. An effort to obtain full-length cDNA was attempted by 5' rapid ampliation ofcDNA ends (5' RACE).ResultThe experimental brain abscess model was established successfully in the rat. 17 differentially expressed cDNA fragments were cloned and identified. Among these fragments, 7 fragments showed highly homologous to known sequenceswith known function and 3 fragments showed known sequences with unknown function in Genebank nr database, 5 fragments showed highly homologous to EST in EST database, 2 fragments showed no homologous in nr or EST database. The sequence data of these 2 fragments, Frag G3-2 and Frag G3-3, were submitted to Genebank with accession No. CD490310 and CK.826599. 7 known sequences with known function includes heterogeneous nuclear ribonucleoprotein F (hnRNP F), minor histocompatibility antigen (mHA) HI3, guanosine diphosphate dissociation inhibitor 3(GDI3), intersectin 1(ITSN), ribosomal protein S4 X-linked(Rps4x), SPT3-associated factor 42 and Ras-associated protein(Rap1). All fragments were located in chromosomes. 3 fragments were prolongated by electronic cloning and confirmed by RT-PCR. The attempt to obtain full-length cDNA was unsuccessful.ConclusionsThe histopathologic features of the rat experimental abscesses produced by direct intracerebral injection of stapbylococcus aureus are similar to other animal models and to human abscess. The molecular mechanism of brain abscess is complicated. Activation of G proteins signaling pathway, especially activation ofG a effectors signaling pathway, play an important role. After stapbylococcusaureus exposure, differential pre-transcriptional regulation mechanisms take place. Then large numbers of genes were expressed and new proteins were synthesized through the alternative splicing of pro-mRNA. As a result, over-expressed mHA H13 may cause autoimmunity of inflammatory cells versus brain tissue.