Rab32 GTPase, as a direct target of miR-30b/c, controls the intracellular survival of Burkholderia pseudomallei by regulating phagosome maturation

Abstract

Burkholderia pseudomallei is a gram-negative, facultative intracellular bacterium, which causes a disease known as melioidosis. Professional phagocytes represent a crucial first line of innate defense against invading pathogens. Uptake of pathogens by these cells involves the formation of a phagosome that matures by fusing with early and late endocytic vesicles, resulting in killing of ingested microbes. Host Rab GTPases are central regulators of vesicular trafficking following pathogen phagocytosis. However, it is unclear how Rab GTPases interact with B . pseudomallei to regulate the transport and maturation of bacterial-containing phagosomes. Here, we showed that the host Rab32 plays an important role in mediating antimicrobial activity by promoting phagosome maturation at an early phase of infection with B . pseudomallei . And we demonstrated that the expression level of Rab32 is increased through the downregulation of the synthesis of miR-30b/30c in B . pseudomallei infected macrophages. Subsequently, we showed that B . pseudomallei resides temporarily in Rab32-positive compartments with late endocytic features. And Rab32 enhances phagosome acidification and promotes the fusion of B . pseudomallei -containing phagosomes with lysosomes to activate cathepsin D, resulting in restricted intracellular growth of B . pseudomallei . Additionally, Rab32 mediates phagosome maturation depending on its guanosine triphosphate/guanosine diphosphate (GTP/GDP) binding state. Finally, we report the previously unrecognized role of miR-30b/30c in regulating B . pseudomallei -containing phagosome maturation by targeting Rab32 in macrophages. Altogether, we provide a novel insight into the host immune-regulated cellular pathway against B . pseudomallei infection is partially dependent on Rab32 trafficking pathway, which regulates phagosome maturation and enhances the killing of this bacterium in macrophages.

Transcriptome Analysis Reveals Unfolded Protein Response Was Induced During the Early Stage of Burkholderia pseudomallei Infection in A549 Cells

“…Elucidating the cellular response to B. pseudomallei infection will aid in unraveling the pathogenic mechanisms of the pathogen. We previously reported that B. pseudomallei could modulate autophagy (Li et al, 2015) and Rab32-mediated phagocytic vesicle transport to evade intracellular killing in host cells (Hu et al, 2019).…”

“…It could also evade LC3-associated phagocytosis (Gong et al, 2011 ) and induce macrophages pyroptosis (Bast et al, 2014 ). Our previous research demonstrated that B. pseudomallei could interfere with the progress of Rab32 GTPase-mediated B. pseudomallei -containing phagosomes maturation and escape into the cytosol (Hu et al, 2019 ). B. pseudomallei could evade autophagy by regulating ATG10 in A549 cells (Li et al, 2015 ).…”

VARP and Rab9 Are Dispensable for the Rab32/BLOC-3 Dependent Salmonella Killing

“…Studies from our laboratory and others, have shown that in macrophages, the BRAM pathway controls not only infection by bacterial pathogens such as Salmonella Typhi, Staphylococcus aureus, Listeria monocytogenes, and Burkholderia pseudomallei (Seto et al, 2011;Spanò and Galań, 2012;Li et al, 2016;Hu et al, 2019) but it also has an important role in controlling Candida albicans infection in mice (Baldassarre et al, 2020). However, nothing is known about how the BRAM pathway is regulated and what other proteins are part of this important antimicrobial pathway.…”

Transcriptome Analysis Reveals Dynamic Changes of Inflammation and Stress Responses during Different Infected Stages with Burkholderia pseudomallei

“…Our team previous research found that B. pseudomallei could evade autophagy by 3 novel miRNAs of MIR4458, MIR4667-5p, and MIR4668-5p targeted regulation of ATG10 in A549 cells [10]. Macrophages could up-regulate Rab32 GTPase through reducing miR-30b/30c to accelerate B. pseudomallei-containing phagosomes maturation [11]. However, B.…”