Reduced extracellular collagen secretion levels in AA-stimulated MC3T3-E1 OBs expressing mutant Rab GTPases.

<p>Cells were plated on CYTOO coverslips for 1 hour, transfected with Rab1-DN-GFP (A), Rab3d-GFP (B) or Rab27b-GFP (C) for 9 hours during which they were differentiated with AA for 8 hours. Cells were then fixed and immunostained with extracellular collagen in cyan and total procollagen shown in red. Nuclei were stained with DAPI (blue). The dotted circles in black and white images point to extracellular collagen in transfected cells. Scale bars, 10 µm. (D–F) Graphs present the mean collagen intensity levels in cells expressing mutant Rabs for 9 hours compared to untransfected cells, which was quantified using ImageJ. Expression of all three mutant Rabs resulted in a significant reduction in extracellular collagen secretion. * p<0.05. All data are reported as mean ± SEM from 3 independent experiments (n = 50).