Multiprotein Bridging Factor 1 (MBF1) Responds To Cold Stress By Regulating The Expression Of Metabolism Relevant Genes In Drosophila

In nature, low temperature, oxidation, hyperthermia, soil salination and drought have bad effects on the growth and survival of animals and plants, such as the growth vigor is weak and thin, the number decreases clearly, even the worse one will lead to dying out.Based on past research, transcription factors and regulatory genes are main factors mediated the acclimation of animals and plants to environmental stress. The transcriptional coactivator has closely relationship with the activity of transcriptional factors, it can enhance the transcription activity through increasing the combination of transcriptional factors to cis-acting element.The transcriptional coactivator multiprotein bridging factor 1(MBF1) is highly conserved during evolution, and its gene sequences is conserved across species from the Archaea to Human. MBF1 is involved in diverse biological processes such as endothelial cell differentiation, hormonal regulation, central nervous system development, hormone-regulated lipid metabolism and histidine metabolism.It was first purified from the posterior silk gland of the silkmoth. MBF1 proteins from different organisms bind with TBP which is general transcription factor through interacting with GCN4, c-Jun, ATF1 or other nuclear receptors, finally activate gene transcription. The MBF1 are not only highly conserved during evolution, but also conserved in function, and it can participate in a variety of adversity stress reaction. It can improve the ability of responsing stress through regulating many signaling pathways.In this study, we taked model organism drosophila as research materials. Getting the mbf1 genomic sequence via the methods of isolating RNA, reverse transcription and PCR(Polymerase Chain Reaction), and the length is 4574 bp. We named it as gmbf1.We constructed expression vector CaSpeR-gmbf1 after cloning the genes. The expression vector CaSpeR-gmbf1 was transformed into Drosophila melanogaster by microinjection method which contains four copies of mbf1+. We obtained the rescue strain P[gmbf1];mbf1-by hybridization method. We analyzed the survival rate experiment of the wild type(WT), mbf1 mutant, the rescue strain and the overexpression during the treatment of cold hardening, and found that the mbf1 are required for the resistance against cold stress. We examined the expression of mbf1 by real time RT-PCR after cold hardening treatment, and the result showed that the expression levels of mbf1 was 1.5-fold higher than that at baseline after 2 hours of exposure to cold treatment. Immunofluorescence experiment revealed that MBF1 transfered from the cytosol to the nucleus response to cold stress, this could express that MBF1 can realize the aim of regulating the activity of target genes, and then enhance cold resistance.To address how MBF1 responds to cold stress, we explored which genes changes in mbf1 mutant with Microarray hybridization experiment compared with the WT. And then choosing several genes which is related to metabolic processes, we need to find how many genes can be regulated by the MBF1 and required for the resistance against cold stress using real time RT-PCR. In the mbf1 mutant, the expression of Nmdmc and CG5804 was decreased, and the expression of CG14893 and CG11598 was increased. After the treatment of cold hardening, the expression of Nmdmc and CG5804 was increased, and the expression of CG14893 and CG11598 was decreased. Our data suggest that the MBF1 contributes to the cold hardening response by regulating some genes that are involved in metabolic processes.