Viability, morphology, and proteome of Mycobacterium smegmatis MSMEG_0319 knockout strain

Mycobacterium tuberculosis Rv1987 protein induces M2 polarization of macrophages through activating the PI3K/Akt1/mTOR signaling pathway

Mycobacterium tuberculosis (Mtb) can subvert host immune responses and survive in macrophages. Specific Mtb antigens play a critical role in this process. Rv1987, a secretory protein encoded by the gene rv1987 in the region of difference-2 (RD2) of the Mtb genome, is specifically expressed in pathogenic mycobacteria. Our previous work proved that Rv1987 induced a Th2 response in mice and enhanced mycobacterial survival in mouse lungs, but its effect on macrophages, the most important effector immune cell involved in killing Mtb, remains unclear. In this study, we used an M. smegmatis strain overexpressing Rv1987 protein to infect alveolar macrophages and the macrophage cell line RAW264.7 and analyzed the effect of Rv1987 protein on macrophage polarization. Rv1987 induced M2 polarization in macrophages both in vivo and in vitro. The bactericidal ability of these M2 polarized macrophages decreased remarkably, which resulted in the increased survival of bacteria in macrophages. Proteomics, RT-qPCR and western blotting results revealed that the PI3K/Akt1/mTOR signaling pathway was activated in Rv1987-induced M2 macrophages. Meanwhile, the SHIP molecule, a negative regulator of the PI3K/Akt1/mTOR signaling pathway, was significantly downregulated. These results suggest that Rv1987 plays an important role in modulating the host immune response and could be established as a potential drug target.

An integrated course based on two dimensional-electrophoresis and mass spectrometry analysis to teach proteomic techniques for undergraduate students

Here, we developed an integrated course based on two dimensional-electrophoresis and spectrometry mass (2DE-MS) technique for undergraduate students to help them learn proteomic techniques. The soluble proteins in wild type and gene knockout bacteria were separated by 2DE and the differently expressed proteins were identified by MS analysis. The proteomic data was finally confirmed by RT-PCR detection. The separated experiments of 2DE, MS, RNA isolation, RT-PCR, as well as essential bioinformatic analysis, were integrated into a one-week course, which provided students an opportunity to systematically understand the proteomic techniques and their applications in current scientific research. © 2018 by The International Union of Biochemistry and Molecular Biology, 46:354-360, 2018.