Figure 7.

MBNL sequestration on expanded CUG^exp transcripts. (A) Life cell imaging of cells transfected with CUG^exp, mCherry-MBNL1 and GFP-MBNL3. MBNL1 localizes primarily in nucleus, whereas MBNL3 is predominately cytoplasmic. (B) Time-lapse sequence images of CUG^exp-GFP-MBNL1 complexes (green). Raw data were processed with Imaris software. (C) Time-lapse sequence images of a cell transiently transfected with CUG^exp and MBNL1 fused with Dendra2 fluorescence protein. MBNL1 accumulated in two distinct nuclear foci. Laser stimulated Dendra2-MBNL photoconversion from green (emission 507 nm) to red (emission 573 nm) in a single focus reveals dynamic exchange of MBNL between the focus and surrounding nucleoplasm in the course of minutes. Yellowish center of focus core might suggest that MBNL proteins localized in the focus core are less prone to exchange. Below each image, a scheme representing the experimental scheme. (B,C) Images adapted from Reference [135].