The Role of Mcl-1 in S. aureus-Induced Cytoprotection of Infected Macrophages
Figure 4
Effect of Mcl-1 expression on cytoprotection induced by S. aureus in hMDMs. (a) Human macrophages were treated with an MCL1 siRNA (siMCL1) or a nonspecific siRNA (siNS). At 24 h following transfection macrophages were infected with S. aureus at an MOI 1 : 50. After additional 24 h cells were collected and Mcl-1 expression was detected by immunoblot. Data are representative of three separate experiments using hMDMs derived from different donors. (b) The increase in caspase-3 activity (RFU/min) induced by STS in MCL1 knockdown macrophages infected with S. aureus. Twenty-four hours after treatment with siRNA, hMDMs were infected with S. aureus (24 h), followed by treatment with STS at a concentration of 1 μM for 18 h. The measurement of caspase-3 activity (RFU/min) in cell lysates was performed using DEVD-AFC as a substrate. The figure is representative of three experiments, using hMDMs cultures obtained from different donors. Light bars—STS, dark bars—Sa + STS. Data represent means SD. ; ; . (c) Increased susceptibility to the cytotoxic effects of staurosporine (STS) in MCL1 knockdown macrophages infected with S. aureus. Twenty-four hours after treatment with siRNA, hMDMs were infected with S. aureus (24 h), followed by treatment with STS at a concentration of 1 μM for 24 h. Plasma membrane permeabilisation or cell lysis induced in the hMDMs was assessed by measuring LDH activity in the culture medium. LDH activity in the media of cells treated only with STS was arbitrarily set as 100%. Results were calculated based on data ( SD) from three separate experiments. .
