Fig. 1: Identification of complement 3 (C3) and its transcription activator. | Communications Biology

Fig. 1: Identification of complement 3 (C3) and its transcription activator.

From: Inhibition of complement C3 prevents osteoarthritis progression in guinea pigs by blocking STAT1 activation

Fig. 1

a, e The conditioned media was collected after primary human chondrocytes were stimulated with IL-1β for 66 h. Complement factors were detected with western blotting under non-reducing condition (a). b A schematic approach to identify transcription factors that increase the transcription of C3. Biotinylated C3 promoter DNA was transfected into human primary articular chondrocytes. After, these cells were stimulated with IL-1β for 30 min. Cross-linking reagent, formaldehyde, was added to cross-link DNA and proteins. The cell was lysed and the biotinylated C3 promoter-protein complexes were pulled down with streptavidin beads. The complexes were washed and cross-linking was reversed. The protein components were analyzed with LC-MS/MS. C3 mRNA transcription was affected by fludarabine (50 μM) at different time points after IL-1β stimulation by use of RT-PCR (c), and RT-qPCR (d) The error bars represent standard error of mean. e The protein levels of C3 and complement factor B were affected by fludarabine after IL-1β stimulation via western blotting under reduced conditions. f CHIP-PCR assay of transcription factor STAT1’s binding region in C3 promoter. [IL-1β]: 35 ng/ml.

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