Differential recruitment of CD63 and Rab7-interacting-lysosomal-protein to phagosomes containing Mycobacterium tuberculosis in macrophages
ABSTRACT M.tb is an intracellular pathogen which survives within the phagosomes of host macrophages by inhibiting their fusion with lysosomes. Here, it has been demonstrated that a lysosomal glycoprotein, CD63, is recruited to the majority of M.tb phagosomes, while RILP shows limited localization. This is consistent with the author's findings that CD63, but not RILP, is recruited to the phagosomes in macrophages expressing the dominant negative form of Rab7. These results suggest that M.tb phagosomes selectively fuse with endosomes and lysosomes to escape killing activity while acquiring nutrients.
- SourceAvailable from: Yukio Koide
[Show abstract] [Hide abstract]
- "Immunofluorescence and thin-section electron microscopic analyses were performed as described previously [23,24]. For immunofluorescence microscopy, macrophages were stained with anti-LAMP2 antibody (1:25 v/v), anti-LC3 antibody (1:25 v/v), anti-p62 antibody (1:25 v/v), anti-ubiquitin antibody (1:25 v/v), anti-Beclin1 (1:25 v/v) or anti-GM130 (1:10 v/v). "
ABSTRACT: Rab39a has pleiotropic functions in phagosome maturation, inflammatory activation and neuritogenesis. Here, we characterized Rab39a function in membrane trafficking of phagocytosis and autophagy induction in macrophages. Rab39a localized to the periphery of LAMP2-positive vesicles and showed the similar kinetics on the phagosome to that of LAMP1. The depletion of Rab39a did not influence the localization of LAMP2 to the phagosome, but it augments the autophagosome formation and LC3 processing by lipopolysaccharide (LPS) stimulation. The augmentation of autophagosome formation in Rab39a-knockdown macrophages was suppressed by Atg5 depletion or an inhibitor for phosphatidylinostol 3-kinase (PI3K). Immunoprecipitation analysis revealed that Rab39a interacts with PI3K and that the amino acid residues from 34(th) to 41(st) in Rab39a were indispensable for this interaction. These results suggest that Rab39a negatively regulates the LPS-induced autophagy in macrophages.PLoS ONE 12/2013; 8(12):e83324. DOI:10.1371/journal.pone.0083324 · 3.23 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Mycobacterium tuberculosis is an extremely successful pathogen that demonstrates the capacity to modulate its host both at the cellular and tissue levels. At the cellular level, the bacterium enters its host macrophage and arrests phagosome maturation, thus avoiding many of the microbicidal responses associated with this phagocyte. Nonetheless, the intracellular environment places certain demands on the pathogen, which, in response, senses the environmental shifts and upregulates specific metabolic programs to allow access to nutrients, minimize the consequences of stress, and sustain infection. Despite its intracellular niche, Mycobacterium tuberculosis demonstrates a marked capacity to modulate the tissues surrounding infected cells through the release of potent, bioactive cell wall constituents. These cell wall lipids are released from the host cell by an exocytic process and induce physiological changes in neighboring phagocytes, which drives formation of a granuloma. This tissue response leads to the generation and accumulation of caseous debris and the progression of the human tuberculosis granuloma. Completion of the life cycle of tuberculosis requires damaging the host to release infectious bacteria into the airways to spread the infection. This damage reflects the pathogen's ability to subvert the host's innate and acquired immune responses to its own nefarious ends.Immunological Reviews 03/2011; 240(1):252-68. DOI:10.1111/j.1600-065X.2010.00984.x · 10.12 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Mycobacterium tuberculosis (M. tb) is an intracellular pathogen that can replicate within infected macrophages. The ability of M. tb to arrest phagosome maturation is believed to facilitate its intracellular multiplication. Rab GTPases regulate membrane trafficking, but details of how Rab GTPases regulate phagosome maturation and how M. tb modulates their localization during inhibiting phagolysosome biogenesis remain elusive. We compared the localization of 42 distinct Rab GTPases to phagosomes containing either Staphylococcus aureus or M. tb. The phagosomes containing S. aureus were associated with 22 Rab GTPases, but only 5 of these showed similar localization kinetics as the phagosomes containing M. tb. The Rab GTPases responsible for phagosome maturation, phagosomal acidification and recruitment of cathepsin D were examined in macrophages expressing the dominant-negative form of each Rab GTPase. LysoTracker staining and immunofluorescence microscopy revealed that Rab7, Rab20 and Rab39 regulated phagosomal acidification and Rab7, Rab20, Rab22b, Rab32, Rab34, Rab38 and Rab43 controlled the recruitment of cathepsin D to the phagosome. These results suggest that phagosome maturation is achieved by a series of interactions between Rab GTPases and phagosomes and that differential recruitment of these Rab GTPases, except for Rab22b and Rab43, to M. tb-containing phagosomes is involved in arresting phagosome maturation and inhibiting phagolysosome biogenesis.Traffic 04/2011; 12(4):407-20. DOI:10.1111/j.1600-0854.2011.01165.x · 4.35 Impact Factor