Exp Mol Med.  2011 Feb;43(2):101-110. 10.3858/emm.2011.43.2.012.

Ligation of CD40 receptor in human B lymphocytes triggers the 5-lipoxygenase pathway to produce reactive oxygen species and activate p38 MAPK

• Ha YJ
• Seul HJ
• Lee JR

• KMID: 1097267
• DOI: http://doi.org/10.3858/emm.2011.43.2.012

Abstract

Previously, we reported that CD40-induced production of reactive oxygen species (ROS) by NADPH oxidase requires the TNF receptor-associated factor (TRAF) 3, as well as the activities of phosphatidylinositol 3-kinase (PI3K) and Rac1. Here we investigated the possible mechanisms of the production of ROS after CD40 ligation in B cells. We describe an alternative ROS production pathway that is triggered by CD40 ligation, involves 5-lipoxygenase (5-LO), and results in activation of p38 MAPK. Our studies in Raji human B lymphomas revealed that CD40-induced ROS production by 5-LO also requires the activities of PI3K and Rac1. In contrast to the NADPH oxidase pathway, however, TRAF molecules are not required for the CD40-induced ROS production by 5-LO. The association of CD40 with 5-LO is dependent on CD40 ligation in Raji B cells, and co-immunoprecipitation experiments using epitope-tagged proteins transiently expressed in human embryonic kidney 293T cells revealed the role of the regulatory subunit of PI3K, p85, in this association. Collectively, these data suggest a separate pathway for the CD40-induced ROS production in B cells and demonstrate that this pathway requires 5-LO via direct association of p85 with both CD40 and 5-LO.

Keyword

antigens, CD40; arachidonate 5-lipoxygenase; B-lymphocytes; p38 mitogen-activated protein kinases; phosphatidylinositol 3-kinase; reactive oxygen species

MeSH Terms

Antigens, CD40/*metabolism
Arachidonate 5-Lipoxygenase/*metabolism
B-Lymphocytes/*enzymology/immunology
CD40 Ligand/metabolism
Cell Line, Tumor
*Enzyme Activation
HEK293 Cells
Humans
Phosphatidylinositol 3-Kinases/metabolism
Protein Binding
*Reactive Oxygen Species/metabolism
Signal Transduction
p38 Mitogen-Activated Protein Kinases/*metabolism
rac GTP-Binding Proteins/metabolism