RNA expression of <i>MBNL</i> isoforms in myogenic cell cultures with and without expanded (CTG)2600 repeat.

(A) Schematic outline of the CRISPR/Cas9 editing procedure by which the (CTG)2600 repeat was excised from the DMPK gene in the DM1 myoblast cell line named DM11 [23]. As a result, a panel of eight isogenic myoblast cell lines was obtained: four non-edited clonal cell lines with expanded (CTG)2600 repeat (the parental cell line and three independent clones) and four clonal lines from which the mutant repeat was removed. (B) MBNL1, MBNL2 and MBNL3 expression in proliferating myoblasts determined by RNA-seq. (C-E) Quantification of MBNL1, MBNL2 and MBNL3 RNA levels in proliferating myoblasts (day -2) and day 0 or 5 of myogenic differentiation measured by RT-qPCR. All bars show the mean values for the four cell lines with and without (CTG)2600 repeat expansion, all values are relative to the parental cell line.