Titin Circular RNAs Create a Back-Splice Motif Essential for SRSF10 Splicing.

Autor:	Tijsen AJ; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., Cócera Ortega L; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., Reckman YJ; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., Zhang X; Imperial College London, South Kensington Campus, London, UK (X.Z., J.S.W.)., van der Made I; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., Aufiero S; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., Li J; Medical Biology, Amsterdam Cardiovascular Sciences (J.L., H.D.D.), Amsterdam, The Netherlands., Kamps SC; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., van den Bout A; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands., Devalla HD; Medical Biology, Amsterdam Cardiovascular Sciences (J.L., H.D.D.), Amsterdam, The Netherlands., van Spaendonck-Zwarts KY; Clinical Genetics (K.Y.v.S.-Z.), Amsterdam, The Netherlands., Engelhardt S; DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany (S.E.).; Institut für Pharmakologie und Toxikologie, Technische Universität München, Munich, Germany (S.E.)., Gepstein L; The Sohnis Family Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion-Institute of Technology, Haifa, Israel (L.G.)., Ware JS; Imperial College London, South Kensington Campus, London, UK (X.Z., J.S.W.)., Pinto YM; Amsterdam UMC, University of Amsterdam, Departments of Experimental Cardiology, Amsterdam Cardiovascular Sciences (A.J.T., L.C.O., Y.J.R., I.v.d.M., S.A., S.C.K., A.v.d.B., Y.M.P.), Amsterdam, The Netherlands.
Jazyk:	angličtina
Zdroj:	Circulation [Circulation] 2021 Apr 13; Vol. 143 (15), pp. 1502-1512. Date of Electronic Publication: 2021 Feb 15.
DOI:	10.1161/CIRCULATIONAHA.120.050455
Abstrakt:	Background: TTN (Titin), the largest protein in humans, forms the molecular spring that spans half of the sarcomere to provide passive elasticity to the cardiomyocyte. Mutations that disrupt the TTN transcript are the most frequent cause of hereditary heart failure. We showed before that TTN produces a class of circular RNAs (circRNAs) that depend on RBM20 to be formed. In this study, we show that the back-splice junction formed by this class of circRNAs creates a unique motif that binds SRSF10 to enable it to regulate splicing. Furthermore, we show that one of these circRNAs (cTTN1) distorts both localization of and splicing by RBM20. Methods: We calculated genetic constraint of the identified motif in 125 748 exomes collected from the gnomAD database. Furthermore, we focused on the highest expressed RBM20-dependent circRNA in the human heart, which we named cTTN1. We used shRNAs directed to the back-splice junction to induce selective loss of cTTN1 in human induced pluripotent stem cell-derived cardiomyocytes. Results: Human genetics suggests reduced genetic tolerance of the generated motif, indicating that mutations in this motif might lead to disease. RNA immunoprecipitation confirmed binding of circRNAs with this motif to SRSF10. Selective loss of cTTN1 in human induced pluripotent stem cell-derived cardiomyocytes induced structural abnormalities, apoptosis, and reduced contractile force in engineered heart tissue. In line with its SRSF10 binding, loss of cTTN1 caused abnormal splicing of important cardiomyocyte SRSF10 targets such as MEF2A and CASQ2 . Strikingly, loss of cTTN1 also caused abnormal splicing of TTN itself. Mechanistically, we show that loss of cTTN1 distorts both localization of and splicing by RBM20. Conclusions: We demonstrate that circRNAs formed from the TTN transcript are essential for normal splicing of key muscle genes by enabling splice regulators RBM20 and SRSF10. This shows that the TTN transcript also has regulatory roles, besides its well-known signaling and structural function. In addition, we demonstrate that the specific sequence created by the back-splice junction of these circRNAs has important functions. This highlights the existence of functionally important sequences that cannot be recognized as such in the human genome but provides an as-yet unrecognized source for functional sequence variation.
Databáze:	MEDLINE
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