This led us to speculate that
PknG might contribute to the downregulation of PKC-α by mycobacteria and resulting in the increased intracellular survival. To test this hypothesis, we infected THP-1 cells with MS-G and studied the level of macrophage PKC-α. We found that THP-1 cells infected with MS-G show 2.2 and 2.5 fold decreased level of PKC-α when compared to control cells and cells infected with MS respectively (Fig. 4A and 4B). In the same experiment, expression of pknG mRNA in Rv was found to be increased by 32 fold (Fig. 4C). Similar results were observed with J774A.1 cells. Immunoprecipitation (Fig. 4E, 4G) as well as western blot BX-795 research buy analyses (Fig. Cell Cycle inhibitor 4D, 4F) of lysates from J774A.1 cells infected with mycobacteria confirmed downregulation of PKC-α by MS-G. Figure 4 Downregulation of expression of macrophage
PKC-α by recombinant mycobacteria expressing PknG. (A) The THP-1 cells infected with either wild type or recombinant mycobacteria were lysed, and equal amounts of total cell lysates (20 μg) were resolved by SDS-PAGE and immunoblotted with an antibody against PKCα. The lower parts of the blots were probed with an anti-tubulin antibody, to assure equal protein loading, (B) Densitometric analysis of blots shown in fig. 5A, (C) THP-1 cells infected with Rv were osmotically lysed selleck compound and bacteria were recovered by centrifugation and total bacterial RNA was isolated. Total RNA was also isolated from bacterial suspension in RPMI-1640 medium which was used for infection of THP-1 cells. RNA samples were treated with DNAse I and cDNA were prepared using random hexamer primers and was used as template for Cyber Green real time PCR using
pknG specific primers (values presented are normalized against 16S rRNA), Data are means ± standard deviations from five independent experiments each performed in 3 replicates. (** = p < 0.005). (D) experiment identical to 5A was performed with J774A.1 cells, (E) equal amounts of total cell lysates of J774A.1 cells infected with mycobacteria were immunoprecipitated with anti-PKC-α antibody and level of PKC-α was analyzed by immunoblotting. Same amounts of Dichloromethane dehalogenase lysates were also immunoprecipitated with anti-tubulin antibody to serve as control, (F) Densitometric analysis of blots shown in fig. 5D, (G) Densitometric analysis of blots shown in fig.5E. The experiments were repeated at least 3 times. Expression of PknG in MS mimics the effect of PKC-α knockdown PknG down regulates PKC-α, resulting in the inhibition of phagocytosis and increased survival of mycobacteria within macrophages. This raised the possibility of impaired phagocytosis of MS-G in comparison to MS. To test this we infected THP-1 cells with MS and MS-G and compared the phagocytosis. We observed significantly reduced (5 fold less) phagocytosis of MS-G (p < 0.