Characterization of TTN Novex Splicing Variants across Species and the Role of RBM20 in Novex-Specific Exon Splicing
Zhilong Chen
Jiangping Song
Liang Chen
Chaoqun Zhu
Hanfang Cai
Mingming SUn
Allysa Stern
Paul Mozdziak
Ying Ge
Warrie Means
Wei Guo
10.25376/hra.6083228.v1
https://hra.figshare.com/articles/journal_contribution/Characterization_of_TTN_Novex_Splicing_Variants_across_Species_and_the_Role_of_RBM20_in_Novex-Specific_Exon_Splicing/6083228
<p> Titin ( TTN) is a major disease-causing gene in cardiac muscle. Titin ( TTN) contains 363 exons</p>
<p>in human encoding various sizes of TTN protein due to alternative splicing regulated mainly by</p>
<p>RNA binding motif 20 (RBM20). Three isoforms of TTN protein are produced by mutually exclusive</p>
<p>exons 45 (Novex 1), 46 (Novex 2), and 48 (Novex 3). Alternatively splicing in Novex isoforms</p>
<p>across species and whether Novex isoforms are associated with heart disease remains completely</p>
<p>unknown. Cross-species exon comparison with the mVISTA online tool revealed that exon 45 is</p>
<p>more highly conserved across all species than exons 46 and 48. Importantly, a conserved region</p>
<p>between exons 47 and 48 across species was revealed for the first time. Reverse transcript polymerase</p>
<p>chain reaction (RT-PCR) and DNA sequencing confirmed a new exon named as 480 in Novex 3.</p>
<p>In addition, with primer pairs for Novex 1, a new truncated form preserving introns 44 and 45 was</p>
<p>discovered. We discovered that Novex 2 is not expressed in the pig, mouse, and rat with Novex 2</p>
<p>primer pairs. Unexpectedly, three truncated forms were identified. One TTN variant with intron 46</p>
<p>retention is mainly expressed in the human and frog heart, another variant with co-expression of</p>
<p>exons 45 and 46 exists predominantly in chicken and frog heart, and a third with retention of introns</p>
<p>45 and 46 is mainly expressed in pig, mouse, rat, and chicken. Using Rbm20 knockout rat heart,</p>
<p>we revealed that RBM20 is not a splicing regulator of Novex variants. Furthermore, the expression</p>
<p>levels of Novex variants in human hearts with cardiomyopathies suggested that Novexes 2 and 3</p>
<p>could be associated with dilated cardiomyopathy (DCM) and/or arrhythmogenic right ventricular</p>
<p>cardiomyopathy (ARVC). Taken together, our study reveals that splicing diversity of Novex exons</p>
<p>across species and Novex variants might play a role in cardiomyopathy.</p>
2018-04-09 14:29:00
TTN
RBM20
Novex isoforms
cardiomyopathy
alternative splicing
Cell Biology
Molecular Biology
Signal Transduction
Physiology