Sphingosine kinase-1 (SphK-1) regulates Mycobacterium smegmatis infection in macrophages.
Sphingosine kinase-1 is known to mediate Mycobacterium smegmatis induced inflammatory responses in macrophages, but its role in controlling infection has not been reported to date. We aimed to unravel the significance of SphK-1 in controlling M. smegmatis infection in RAW 264.7 macrophages. Our results demonstrated for the first time that selective inhibition of SphK-1 by either D, L threo dihydrosphingosine (DHS; a competitive inhibitor of Sphk-1) or Sphk-1 siRNA rendered RAW macrophages sensitive to M. smegmatis infection. This was due to the reduction in the expression of iNOs, p38, pp-38, late phagosomal marker, LAMP-2 and stabilization of the RelA (pp-65) subunit of NF-kappaB. This led to a reduction in the generation of NO and secretion of TNF-alpha in infected macrophages. Congruently, overexpression of SphK-1 conferred resistance in macrophages to infection which was due to enhancement in the generation of NO and expression of iNOs, pp38 and LAMP-2. In addition, our results also unraveled a novel regulation of p38MAPK by SphK-1 during M. smegmatis infection and generation of NO in macrophages. Enhanced NO generation and expression of iNOs in SphK-1++ infected macrophages demonstrated their M-1(bright) phenotype of these macrophages. These findings thus suggested a novel antimycobacterial role of SphK-1 in macrophages.
Prakash
Hridayesh
H
Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany. h.prakash@dkfz-heidelberg.de
Lüth
Anja
A
Grinkina
Natalia
N
Holzer
Daniela
D
Wadgaonkar
Raj
R
Gonzalez
Alexis Perez
AP
Anes
Elsa
E
Kleuser
Burkhard
B
D000818:Animals; D008070:Lipopolysaccharides / Q000494:pharmacology; D008246:Lysophospholipids / Q000096:biosynthesis; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009165:Mycobacterium Infections, Nontuberculous / Q000201:enzymology* / Q000382:microbiology / Q000473:pathology*; D020102:Mycobacterium smegmatis / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D015203:Reproducibility of Results; D013110:Sphingosine / Q000031:analogs & derivatives / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000099157:Sphingosine Kinase
D008070:Lipopolysaccharides; D008246:Lysophospholipids; D009569:Nitric Oxide; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate