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Distinct LPS-induced signals regulate LPS uptake and morphological changes in medfly hemocytes
Anastasios N Soldatos1, Aristea Metheniti, Irene Mamali
1University of Patras, Department of Biology, Patras 265 00, Greece.
Insect Biochemistry and Molecular Biology
|October 18, 2003
Summary
Lipopolysaccharide (LPS) activates medfly hemocyte signaling pathways, including Ras/MEK/ERK and PI-3K, influencing cell shape and LPS uptake. This uptake is actin-independent, similar to mammals.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Lipopolysaccharide (LPS) activates Ras/ERK in medfly hemocytes.
- Insect hemocyte phagocytosis involves integrins and FAK/Src signaling.
- Understanding conserved signaling mechanisms between insects and mammals is crucial.
Purpose of the Study:
- To elucidate LPS effects on medfly hemocytes.
- To understand the regulation of conserved signaling pathways.
- To investigate the roles of specific signaling pathways in LPS response.
Main Methods:
- Stimulation of hemocytes with LPS, E. coli, RGD, fibronectin, and heat shock.
- Inhibition of signaling pathways using manumycin A, toxin A, U0126, PD98059, and wortmannin.
- Assessment of ERK activation, cell morphology changes, and LPS endocytosis.
Main Results:
- LPS, E. coli, and other stimuli activate hemocyte ERK via an LPS receptor and integrin-mediated process.
- LPS induces hemocyte morphology changes and activates Ras/MEK/ERK, PI-3K/ERK, and Rho pathways.
- Ras, MEK, and PI-3K are involved in ERK activation; PI-3K has dual roles in cell shape and LPS uptake.
- ERK activation is independent of actin cytoskeleton remodeling, indicating actin-independent LPS endocytosis.
Conclusions:
- Medfly hemocyte ERK is activated by LPS through distinct receptor and integrin-mediated pathways.
- PI-3K plays a dual role in hemocyte shape modulation and LPS endocytosis.
- LPS endocytosis in medfly hemocytes is independent of actin cytoskeleton remodeling, mirroring mammalian systems.