Fig. 5.

SMALED2 patient fibroblasts show delayed VSV-G secretion compared to controls. a is an example of a human fibroblast transfected with a plasmid encoding for the thermo-sensitive-GFP vesicular stomatitis virus glycoprotein (ts0–45 VSV-G) at 32 °C. The time prior to fixation is indicated on the top; staining with an anti-VSV-G [8G5F11] against a surface epitope of VSV-G in non-permeabilised cells (top row of panels); GFP staining is shown in the bottom row. Scale bars = 20 μm. At 0 mins, all ts0–45 VSVG is retained within the ER with no surface staining. At 30mins all ts0–45 VSV-G has been trafficked to the Golgi. By 240 mins all ts045-VSV-g has been trafficked to the plasma membrane and is evident in both the GFP (bottom) and anti-VSV-G surface epitope antibody (top)_ panels. b Kinetics of VSV-G secretion in fibroblasts isolated from a patient with SMALED2 (I189F mutation, orange) and an age-matched control (blue) are quantified as the ratio of total surface VSV-G staining to total GFP. The x axis shows the time in minutes at 32 °C prior to fixation (n = 10 cells per condition; **p = 0.008, *p = 0.009; multiple unpaired t-tests corrected for multiple comparisons using the Holm-Sidak method). c shows the average ratio of surface VSV-G to total GFP at 240 min for three independent healthy control and three unrelated SMALED2 (S107L, I189F and R501P) fibroblast cell lines (# p = 0.052, unpaired t-test). Error bars = SEM. The impaired secretion in SMALED2 patient fibroblasts suggests that a similar impairment of secretion may be evident in the muscle of Bicd2^−/− mice and SMALED2 patients