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Splicing Variation of TTN Novex Isoforms Across Species and RBM20 Does Not Regulate Splicing of Novex Isoforms in Cardiac Muscle.
Author(s) -
Chen Zhilong,
Guo Wei
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.650.13
Subject(s) - exon , gene isoform , intron , rna splicing , alternative splicing , biology , gene , genetics , tandem exon duplication , protein isoform , primer (cosmetics) , exon trapping , splice , microbiology and biotechnology , rna , chemistry , organic chemistry
TTN is a major disease‐causing gene in cardiac muscle. TTN contains 363 exons in human encoding various sizes of TTN protein due to alternative splicing regulated mainly by RNA binding motif 20 (RBM20). Three isoforms of TTN protein are produced by alternative exon usages of exon 45 (Novex 1), exon 46 (Novex 2) and exon 48 (Novex 3). It is unknown how these exons are alternatively used in Novex isoforms across species and whether Novex isoforms are associated with heart disease. In this study, we compared alternative exon usage between species with the mVISTA online tool, and found that exon 45 is conserved across all species, but exons 46 and 48 only found in some species. Interestingly, we found a conserved region between exons 47 and 48 across species which has never been characterized before. RT‐PCR and DNA sequencing confirmed that this is a new exon named as 48′ in Novex 3. In addition, with primer pairs for Novex 1, we found two new splicing forms, which one has intron 44 retention and the other has intron 45 retention. With Novex 2 primer pairs, we found that Novex 2 is lack of expression in pig, mouse and rat. A new truncated isoform with intron 46 retention is mainly expressed in human and frog heart, and another new truncated isoform with exon 45 and 46 are co‐expressed predominantly in chicken and frog heart. Using RBM20 knockout heart, we revealed that RBM20 doesn't regulate splicing of Novex isoforms. Finally, we examined the expression levels of Novex isoforms in human heart with cardiomyopathies, and we didn't find any difference. These results suggest that exon usage of Novex isoforms varies across species which is not associated with cardiomyopathies. Hence, their functional role in the heart need be further studied in the future, which is beyond the scope of this study. Support or Funding Information This work was supported by the NIFA‐USDA 1009266, National Institutes of Health NIGMSP20GM103432, AHA BGIA and Faculty‐Grant‐in‐Aid from University of Wyoming. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .