BACKGROUND Mutation in the titin gene (TTN) in left ventricular noncompaction (LVNC) has been reported with a highly heterogeneous prevalence, and the molecular mechanisms underlying the pathogenesis of TTN gene mutation are uncharacteri-zed. In the present study, we identified a novel TTN mutation in a pedigree with LVNC and investigated the potential pathogenic mechanism by functional studies. METHODS The whole-genome sequencing with linkage analysis was performed in a 3-generation family affected by autoso-mal dominant LVNC cardiomyopathy. The clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR/Cas9) technology was used to establish novel truncating mutation in TTN in a rat cardiomyoblast H9C2 cell line in vitro, in which functional studies were carried out and characterized in comparison to its wild-type counterpart. RESULTS A novel truncating mutation TTN p. R2021X was identified as the only plausible disease-causing variant that segreg-ated with disease among the five surviving affected individuals, with an interrogation of the entire genome excluding other po-tential causes. Quantitative reverse transcription-polymerase chain reaction and cellular immunofluorescence supported a haplo-insufficient disease mechanism in titin truncation mutation cardiomyocytes. Further functional studies suggested mitochondrial abnormities in the presence of mutation, including decreased oxygen consumption rate, reduced adenosine triphosphate produc-tion, impaired activity of electron translation chain, and abnormal mitochondrial structure on electron microscopy. Impaired aut-ophagy under electron microscopy accompanied with activation of the Akt-mTORC1 signaling pathway was observed in TTN p. R2021X truncation mutation cardiomyocytes. CONCLUSIONS The TTN p. R2021X mutation has a function in the cause of a highly penetrant familial LVNC. These findings expand the spectrum of titin 's roles in cardiomyopathies and provide novel insight into the molecular basis of titin-truncating variants-associated LVNC.

Xue-Qi DONG;Di ZHANG;Yi QU;Yu-Xiao HU;Chun-Xue YANG;Tao TIAN;Nan XU;Hai-Lun JIANG;Li ZENG;Peng-Yan XIA;Ya-Xin LIU;Rui LIU;Xian-Liang ZHOU

Department of Cardiology,Fuwai Hospital,National Center for Cardiovascular Disease,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing,China;Department of Echocardiography,Fuwai Hospital,Natio-nal Center for Cardiovascular Disease,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing,China;Institute of Medicinal Biotechnology,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing,China;State Key Laboratory of Membrane Biology,Institute of Zoology,Chinese Academy of Science,Beijing,China

老年心脏病学杂志（英文版）

[1]Xue-Qi DONG;Di ZHANG;Yi QU;Yu-Xiao HU;Chun-Xue YANG;Tao TIAN;Nan XU;Hai-Lun JIANG;Li ZENG;Peng-Yan XIA;Ya-Xin LIU;Rui LIU;Xian-Liang ZHOU-.Implication of a novel truncating mutation in titin as a cause of autosomal dominant left ventricular noncompaction)[J].老年心脏病学杂志（英文版）,2022(04):301-314

uncharacteri,zed,autoso,cardiomyoblast,R2021X,segreg,abnormities,aut,ophagy,penetrant,cardiomyopathies

Implication,novel,truncating,mutation,titin,autosomal,dominant,left,ventricular,noncompaction,BACKGROUND,Mutation,TTN,LVNC,has,been,reported,highly,heterogeneous,prevalence,molecular,mechanisms,underlying,pathogenesis,are,In,present,study,identified,pedigree,investigated,potential,pathogenic,by,functional,studies,METHODS,whole,genome,sequencing,linkage,analysis,was,performed,generation,family,affected,cardiomyopathy,clustered,regularly,interspaced,short,palindromic,repeats,associated,protein,CRISPR,Cas9,technology,used,establish,H9C2,line,vitro,which,were,carried,out,characterized,comparison,its,wild,type,counterpart,RESULTS,only,plausible,disease,causing,that,among,five,surviving,individuals,interrogation,entire,excluding,other,causes,Quantitative,reverse,transcription,polymerase,chain,reaction,cellular,immunofluorescence,supported,haplo,insufficient,truncation,cardiomyocytes,Further,suggested,mitochondrial,presence,including,decreased,oxygen,consumption,rate,reduced,adenosine,triphosphate,produc,impaired,activity,electron,translation,abnormal,structure,microscopy,Impaired,accompanied,activation,Akt,mTORC1,signaling,pathway,observed,CONCLUSIONS,familial,These,findings,expand,spectrum,roles,provide,insight,into,basis,variants

0.517806