Fig. 4.

Prolonged and enhanced long-term anterograde secretion of soluble cargo [recombinant horseradish perioxidase (HRP)] by PAECs exposed to MCTP or c-PTIO. PAEC cultures (in triplicate per variable) were transfected with the ssHRP expression vector and exposed to MCTP or c-PTIO 1 day later, the culture medium (1 ml per well) was harvested for the next 5 days, and the cultures were then fixed for immunostaining (A). Each sample of culture medium was assayed in triplicate for peroxidase activity [expressed in arbitrary absorbance units (AU); Ref. 60]; values for background subtraction were generated from medium samples simultaneously harvested from PAEC cultures transfected with only the pCDNA3 vector. HRP activity data derived from each well during the 5-day experiment were normalized in terms of HRP activity obtained from that same well in the first 24-h period (time interval indicated as “0” in A); thus each well acted as its own transfection control. A: experimental protocol. B: summary of data obtained (means ± SE). C: confirmation of Golgi dispersal in cultures at the conclusion of this experiment (scale bar = 50 μm). *P < 0.01 in intraday comparison with respective untreated control at each time point; n = 9 at each time point for each variable (triplicate cultures per variable with each medium sample assayed in triplicate).