1: J Infect Dis. 2009 Nov 1;200(9):1367-70. Role of rsbU and Staphyloxanthin in Phagocytosis and Intracellular Growth of Staphylococcus aureus in Human Macrophages and Endothelial Cells. Olivier AC, Lemaire S, Van Bambeke F, Tulkens PM, Oldfield E. Unité de pharmacologie cellulaire et moléculaire and Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium; 2Department of Chemistry and Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL. In Staphylococcus aureus, rsbU down-regulates agr and stimulates production of staphyloxanthin (STX), an antioxidant that may contribute to intracellular survival after phagocytosis. Using isogenic rsbU(-) and rsbU(+) strains, we show that rsbU causes increased internalization and intracellular growth in both THP-1 macrophages and human umbilical vein endothelial cells (more so for the latter) without change in subcellular localization and that inhibition of STX biosynthesis markedly reduces intracellular growth of the rsbU(+) strain (and of clinical isolates, including USA300; tested with macrophages only) without affecting internalization. Thus, rsbU is important for uptake and for STX biosynthesis and is critical for intracellular multiplication of S. aureus. PMCID: PMC2762113 [Available on 2009/11/01] PMID: 19817587 [PubMed - in process] Related Links sigmaB modulates virulence determinant expression and stress resistance: characterization of a functional rsbU strain derived from Staphylococcus aureus 8325-4. [J Bacteriol. 2002] PMID:12218034 Sigma(B) activity depends on RsbU in Staphylococcus aureus. [J Bacteriol. 2001] PMID:11222581 The influence of agr and sigmaB in growth phase dependent regulation of virulence factors in Staphylococcus aureus. [Proteomics. 2004] PMID:15378746 sigma(B) activity in Staphylococcus aureus is controlled by RsbU and an additional factor(s) during bacterial growth. [Infect Immun. 2001] PMID:11705968 A potential new pathway for Staphylococcus aureus dissemination: the silent survival of S. aureus phagocytosed by human monocyte-derived macrophages. [PLoS One. 2008] PMID:18183290