Content area
Full Text
Inammation, Vol. 36, No. 4, August 2013 (# 2013) DOI: 10.1007/s10753-013-9613-3
Lypopolysaccharide Downregulates the Expression of Selected Phospholipase C Genes in Cultured Endothelial Cells
V. R. Lo Vasco,1,4 M. Leopizzi,2 C. Chiappetta,2 C. Puggioni,2 C. Della Rocca,2 P. Polonia,3
and R. Businaro2
AbstractThe signaling system of phosphoinositides (PI) is involved in a variety of cell and tissue functions, including membrane trafcking, ion channel activity, cell cycle, apoptosis, differentiation, and cell and tissue polarity. Recently, PI and related molecules, such as the phosphoinositidespecic phospholipases C (PI-PLCs), main players in PI signaling were supposed to be involved in inammation. Besides the control of calcium levels, PI-PLCs contribute to the regulation of phosphatydil-inositol bisphosphate metabolism, crucial in cytoskeletal organization. The expression of PI-PLCs is strictly tissue specic and evidences suggest that it varies under different conditions, such as tumor progression or cell activation. In a previous study, we obtained a complete panel of expression of PI-PLC isoforms in human umbilical vein endothelial cells (HUVEC), a widely used experimental model for endothelial cells. In the present study, we analyzed the mRNA concentration of PI-PLCs in lipopolysaccharide (LPS)-treated HUVEC by using the multiliquid bioanalyzer methodology after 3, 6, 24, 48, and 72 h from LPS administration. Marked differences in the expression of most PI-PLC codifying genes were evident.
KEY WORDS: HUVEC; signal transduction; inammation; phospholipase C; gene expression.
INTRODUCTION
When inammation occurs, endothelial cells (EC) in the vessels are the rst elements exposed to mediators circulating in the bloodstream [1]. EC react with nely tuned responses mediated by different pathways, including the phosphoinositide (PI) signal transduction system. The PI pathway contributes to a variety of cell functions, including hormone secretion, neurotransmitter signal transduction, cell growth, membrane trafcking, ion channel activity, cytoskel-
eton regulation, cell cycle control, apoptosis, embryonic development, organogenesis, and cell/tissue polarity [27]. A combination of compartmentalized and temporal changes in the levels of phosphorylated derivatives of PI elicits different cellular responses, including regulation of gene expression, DNA replication, and chromatin degradation [27].
The phosphoinositide-specic phospholipase C (PIPLC) enzymes contribute to the regulation of the spatiotemporal balance of molecules belonging to the PI system. After activation by different stimuli, PI-PLC rapidly cleaves the polar head group of phosphatydil inositol bisphosphate (PIP2), a structural component of the cell membrane. Decrease...