Journal: JCI Insight
Article Title: Schlafen 5 is an intracellular immune checkpoint and controls IFN responses in pancreatic ductal adenocarcinoma
doi: 10.1172/jci.insight.190031
Figure Lengend Snippet: ( A ) RT-qPCR analysis to monitor efficacy of CRISPR/Cas9-mediated SLFN5 KO in PANC-1 (upper panel) and MIA-Pa-Ca-2 (lower panel) cells. Data are expressed as fold change over WT controls, and bar graphs represent mean ± SEM of 3 independent experiments. **** P < 0.0001. ( B ) Scatter plot (derived from high-throughput single-end RNA-seq analysis) showing the relationship between log 2 (fold change) (LFC) of 347 genes differentially expressed in both SLFN5 -KO ( x axis) and WT ( y axis) PANC-1 cells following IFN-α (5,000 IU for 6 hours) treatment. Select IFN-stimulated genes (ISGs) from the Reactome database ( https://www.reactome.org/content/detail/R-HSA-913531 ; identifier R-HAS-913531) are indicated. The red dashed line deviates from the unity line ( y = x , black line) and represents the linear regression fit ( y = 0.948 x + 0.026), capturing the overall trend between the 2 conditions. The slope ( m = 0.948) indicates a near one-to-one correspondence between the conditions, and the intercept ( c = 0.026) suggests minimal baseline difference. The high coefficient of determination ( R 2 = 0.89) reflects that 89% of the variance in WT LFCs is explained by SLFN5 -KO LFCs. ( C and D ) RT-qPCR analyses of relative mRNA expression of the indicated ISGs in SLFN5 -WT and -KO PANC-1 ( C ) and MIA-Pa-Ca-2 ( D ) cells untreated or treated with human IFN-α (5,000 IU, 6 hours). GAPDH was used for normalization and as an internal control. The data are expressed as fold change over the corresponding untreated cells; bar graphs represent mean ± SEM of 3 ( C ) or 4 ( D ) independent experiments. * P < 0.05. ( E ) PANC-1 SLFN5 -WT and-KO cells were stably transduced with an ISRE-luciferase promoter construct. Cells were incubated for 6 hours in the presence or absence of human IFN-α (5,000 IU) and luciferase activity was measured. Data are expressed as fold increase in luciferase activity in response to IFN-α treatment over control untreated samples for each condition. Bar graphs show mean ± SEM of 3 independent experiments. * P = 0.05. ( F ) ChIP for SLFN5 in PANC-1 cells transduced with lentivirus carrying doxycycline-inducible SLFN5-MYC-FLAG fusion construct. Cells were grown in the presence or absence of doxycycline for 48 hours, followed by IFN-α treatment for 6 hours. qPCR was performed on immunoprecipitated DNA with primers for the ISRE elements in the IFIT1 or ISG15 promoter. Primers for the RPL30 promoter were used as control. Data were normalized to their own IgG control and are expressed as fold enrichment over doxycycline-untreated cells. Shown are mean ± SEM of 3 independent experiments. * P < 0.05. Significance assessed by 2-tailed unpaired t test with Welch’s correction ( A ) or 1-tailed unpaired t test with Mann-Whitney test ( C – F ).
Article Snippet: Briefly, 2 μg of the Cas9 Control Double Nickase plasmid (Santa Cruz Biotechnology, sc437281) or 2 μg of the Slfn5 Double Nickase plasmid (Santa Cruz Biotechnology, sc435875-NIC) were transfected into murine luciferase-expressing KPC1199 cells using Lipofectamine 2000 transfection reagent (Thermo Fisher Scientific), according to the manufacturer’s instructions.
Techniques: Quantitative RT-PCR, CRISPR, Derivative Assay, High Throughput Screening Assay, RNA Sequencing, Expressing, Control, Stable Transfection, Transduction, Luciferase, Construct, Incubation, Activity Assay, Immunoprecipitation, MANN-WHITNEY
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