Fig. 2.

MAO inhibition prevents tyramine-induced increase in ROS level in myoblasts from patients affected by ColVI myopathies. (A) Myoblasts from UCMD (P2 and P4), BM (P5) patients, and healthy donors (Ctrl) were incubated with the substrate for both MAO-A and MAO-B tyramine (20 µM), in the absence or in the presence of the MAO inhibitor pargyline (100 µM, as a 20 min pretreatment), namely Tyr or Parg + Tyr, respectively. ROS accumulation was assessed by Mitotracker Red CM-H₂XRos (MTR, 25 nM). Data expressed as the MTR fluorescence after 1 h from the addition of tyramine were normalized to the values obtained in the absence of tyramine (Basal) for each samples. Values are the mean of at least four independent experiments. *P < 0.05 for Tyr-treated vs Basal; #P < 0.05 for Parg + Tyr-treated vs Tyr-treated myoblasts. (B) MAO-B protein level was detected by Western blotting in myoblasts from UCMD (P1-P4), BM (P5) patients, and healthy donors (Ctrl). (C) The bands were quantitated by densitometry and data are expressed as the ratio of MAO-B to Red Ponceau staining. Data shown in the panel are the mean of at least four experiments. *P < 0.05 for each patient vs healthy donor.