Figure 4.

C3 and C3a enter the nucleus after uptake. (A,B) Western blot results showing presence of C3 and C3a in nuclear compartments of Raji cells. The human B cell line, Raji was incubated with NHS, C3 or C3met as a source of C3 either in EDTA-GVB (A) or in Mg-EGTA (B) buffer for 1 h at 37°C. After lysis, cytoplasmic, soluble nuclear, and chromatin-associated nuclear fractions were separated and analyzed by Western blot with the goat polyclonal anti-C3 antibody under non reducing conditions (A) or with the rabbit polyclonal antibody against C3a under reducing condition (B). The purity of distinct cellular fractions was verified using antibodies against B-actin (cytoplasmic marker), lamin B1 (nuclear marker) and histone H2B (chromatin-associated nuclear marker). Results shown are one representative experiment out of three (A) or four (B) independent analyzes. (C) Representative confocal images showing that AlexaFluor 488 labeled C3 enters the nucleus. 2 × 10⁶ Raji cells were incubated with 100 μg/ml C3-AlexaFluor 488 for 30 min at 37°C, fixed and counterstained with DAPI using mounting medium. Representative images are shown from two independent experiments investigating at least 50 cells/analysis.