A high-throughput sphingomyelinase assay using natural substrate.
Sphingomyelinases are a group of hydrolases that cleave sphingomyelin, a common component of plasma membranes, to form ceramide and phosphocholine. Ceramide is a second messenger that is present in virtually all cell types and regulates a variety of cellular functions such as proliferation, differentiation, apoptosis, and inflammation response. Inhibition of sphingomyelinase activity to reduce ceramide concentrations has recently emerged as a potential therapeutic approach for several diseases including atherosclerosis, pathogen infections, inflammation, diabetes, and obesity. To effectively screen compound collections for the identification of new sphingomyelinase inhibitors, we have developed a high-throughput assay utilizing the natural substrate sphingomyelin in 1,536-well plate format. The assay has a signal-to-basal ratio of 6.1-fold in pH 5.0 buffer and 4.3-fold in pH 6.5 buffer, indicating a robust assay for compound library screening. A screen of ~300,000 compounds using this assay led to the identification of eight compounds as sphingomyelinase inhibitors (IC(50)s = 1.7 to 38.2 μM) that exhibited different activities between the natural substrate assay and profluorescence substrate assay. The results demonstrate the robustness and effectiveness of the natural substrate sphingomyelinase assay for screening sphingomyelinase inhibitors.
National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892-3370, USA.
Miao
M
Xu
Ke
K
Liu
Noel
N
Southall
Juan J
JJ
Marugan
Alan T
AT
Remaley
Wei
W
Zheng
D008904:Miniaturization; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism; D013379:Substrate Specificity
D013109:Sphingomyelins; D013108:Sphingomyelin Phosphodiesterase