Our findings show that deregulation of IR splicing due to the DM1 mutation can occur in different mouse tissues, suggesting that CTG repeat expansions might also result in IR misplicing not only in muscles but also in other tissues in DM1 patients.
These data demonstrate that coordinated physical and functional interactions between hnRNP H, CUG-BP1 and MBNL1 dictate IR splicing in normal and DM1 myoblasts.
Thus, these experiments demonstrate that sequestration of MBNL1 by the expanded CUG repeats is the primary determinant of both DM1 focus formation and the abnormal splicing of the IR RNA in DM1 myoblasts.