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Evaluation of antibody reactivity to dystrophin products: does Dp40 really exist?
Takahiro Fujimoto1, Kyoko Itoh1
1Department of Pathology and Applied Biology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan.
Abstract:
Duchenne and Becker muscular dystrophies (DMD/BMD) are caused by mutations in the dystrophin gene. The intron-62 promoter produces Dp71 and the putative shorter isoform Dp40, but antibody specificity and the existence of Dp40 protein remain controversial. Here, we systematically evaluated the reactivity of commonly used anti-dystrophin antibodies toward Dp71 isoforms and Dp40. The Abcam DMD and Novocastra/Leica DYS2 antibodies were Dp71d-specific, whereas the Proteintech DMD, 7A10, and N-terminal Dp71/40 antibodies recognized both Dp71d and Dp71f isoforms. Importantly, ectopic Dp40 was detected using only N-terminal Dp71/40 antibody, and signals previously attributed to Dp40 likely represent proteolytic fragments of Dp71. Sequence analysis further indicates that the Dp40 transcript does not appear to contain a functional polyadenylation signal within its intron 70-derived sequence and instead retains downstream exon-intron sequences, suggesting that it may represent an atypical transcript. These findings define antibody specificity and raise questions regarding the existence of Dp40 protein, providing a framework for future studies on Dp71 and Dp40.
Insights
Antibodies targeting Duchenne muscular dystrophy (DMD) proteins show varied specificity. This study clarifies antibody reactivity, suggesting Dp40 protein may not exist and is likely a fragment of Dp71.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Duchenne and Becker muscular dystrophies (DMD/BMD) result from mutations in the dystrophin gene.
- The intron-62 promoter is associated with Dp71 and the proposed Dp40 isoform, but their existence and antibody recognition are debated.
Purpose of the Study:
- To systematically evaluate the reactivity of common anti-dystrophin antibodies against Dp71 isoforms and Dp40.
- To clarify the specificity of antibodies used in DMD/BMD research.
- To investigate the existence of the Dp40 protein.
Main Methods:
- Systematic evaluation of anti-dystrophin antibody reactivity.
- Western blot analysis to detect protein isoforms.
- Sequence analysis of the Dp40 transcript.
Main Results:
- Specific antibodies (Abcam DMD, Novocastra/Leica DYS2) recognized Dp71d.
- Other antibodies (Proteintech DMD, 7A10, N-terminal Dp71/40) recognized both Dp71d and Dp71f.
- Dp40 was only detected with the N-terminal Dp71/40 antibody; other signals were likely Dp71 fragments.
- Sequence analysis suggests Dp40 is an atypical transcript lacking a functional polyadenylation signal.
Conclusions:
- Antibody specificities for Dp71 isoforms are defined.
- The existence of Dp40 protein is questionable, likely representing proteolytic fragments of Dp71.
- Findings provide a framework for future research on Dp71 and Dp40 in muscular dystrophies.
