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Role of CCTα in Macrophage Secretion
Author(s) -
Tian YONG,
Pate Caroline,
Gunter Chris,
Andreolotti Alberto,
Wang Limin,
SmithSielicki Hope,
Tuomanen Elaine,
Claro Enrique,
Jackowski Suzanne
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a603-a
Subject(s) - knockout mouse , lipopolysaccharide , tumor necrosis factor alpha , secretion , macrophage , cytokine , biology , phospholipase d , endocrinology , microbiology and biotechnology , medicine , chemistry , immunology , signal transduction , in vitro , biochemistry , receptor
CCTα knockout mice had normal numbers of macrophages in vivo, but the cells did not proliferate in vitro. Secretion of the major macrophage cytokines, tumor necrosis factor α (TNFα), interleukin‐1β, and interleukin‐6, was reduced significantly in lipopolysaccharide (LPS) stimulated knockout cells. Western blot analysis showed that LPS signaling and synthesis of the proTNFα was normal, but that processing and release of mature TNFα was defective. Whereas 50% of wild‐type infected with an LD 50 dose of S. pneumoniae LUX succumbed to respiratory infection after 5 days, the knockout mice died from sepsis within 48 hours. Serum cytokine levels in the infected knockout mice were lower than wild‐type controls. Immunocytochemistry and electron microscopy showed that TNFα accumulated in swollen and disorganized Golgi in LPS‐stimulated knockout macrophages. Secretion of apolipoprotein E from the knockout macrophages was not decreased. The basal and LPS‐stimulated DAG levels in the knockout macrophages were substantially higher than in wild‐type cells. Partial inhibition of phospholipase D activity with low concentrations of 1‐butanol restored the ability to secrete TNFα. CCTα is required to replenish Golgi‐associated PtdCho to support cytokine secretion because PtdCho is a substrate for phospholipases, which are activated to produce phosphatidic acid and DAG. (Supported by GM45737 and ALSAC).