TY - JOUR
T1 - Rac1 and Cdc42 are required for phagocytosis, but not NF-κB-dependent gene expression, in macrophages challenged with Pseudomonas aeruginosa
AU - Lee, Donna J.
AU - Cox, Dianne
AU - Li, Juncheng
AU - Greenberg, Steven
PY - 2000/1/7
Y1 - 2000/1/7
N2 - Macrophages respond to Gram-negative bacterial pathogens by phagocytosis and pro-inflammatory gene expression. These responses may require GTPases that have been implicated in cytoskeletal alterations and activation of NF- κB. To determine the role of Rac1 and Cdc42 in signal transduction events triggered by Pseudomonas aeruginosa, we expressed GTP binding-deficient alleles of Rac1 or Cdc42, or Chim-GAP, a Rac1/Cdc42-specific GTPase- activating protein domain, in a subline of RAW 264.7 cells, and challenged the transfected cells with a laboratory strain of P. aeruginosa, PAO1. Expression of Rac1 N17, Cdc42 N17, or Chim-GAP led to a marked reduction of phagocytosis. In contrast, nuclear translocation of p65 NF-κB was unaffected by expression of the same constructs. Incubation of macrophages with PAO1 led to NF-κB-dependent expression of inducible nitric-oxide synthase, COX-2, and tumor necrosis factor-α, which was unaffected by inhibition of Rac1 or Cdc42 function. Isogenic strains of PAO1 that lacked surface adhesins were poorly ingested; however, they induced pro-inflammatory gene expression with an efficiency equal to that of PAO1. These results indicate that the signal transduction events leading to phagocytosis and pro-inflammatory protein expression are distinct. Rac1 and Cdc42 serve as effectors of phagocytosis, but not NF-κB-dependent gene expression, in the macrophage response to P. aeruginosa.
AB - Macrophages respond to Gram-negative bacterial pathogens by phagocytosis and pro-inflammatory gene expression. These responses may require GTPases that have been implicated in cytoskeletal alterations and activation of NF- κB. To determine the role of Rac1 and Cdc42 in signal transduction events triggered by Pseudomonas aeruginosa, we expressed GTP binding-deficient alleles of Rac1 or Cdc42, or Chim-GAP, a Rac1/Cdc42-specific GTPase- activating protein domain, in a subline of RAW 264.7 cells, and challenged the transfected cells with a laboratory strain of P. aeruginosa, PAO1. Expression of Rac1 N17, Cdc42 N17, or Chim-GAP led to a marked reduction of phagocytosis. In contrast, nuclear translocation of p65 NF-κB was unaffected by expression of the same constructs. Incubation of macrophages with PAO1 led to NF-κB-dependent expression of inducible nitric-oxide synthase, COX-2, and tumor necrosis factor-α, which was unaffected by inhibition of Rac1 or Cdc42 function. Isogenic strains of PAO1 that lacked surface adhesins were poorly ingested; however, they induced pro-inflammatory gene expression with an efficiency equal to that of PAO1. These results indicate that the signal transduction events leading to phagocytosis and pro-inflammatory protein expression are distinct. Rac1 and Cdc42 serve as effectors of phagocytosis, but not NF-κB-dependent gene expression, in the macrophage response to P. aeruginosa.
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U2 - 10.1074/jbc.275.1.141
DO - 10.1074/jbc.275.1.141
M3 - Article
C2 - 10617597
AN - SCOPUS:0034614548
SN - 0021-9258
VL - 275
SP - 141
EP - 146
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 1
ER -