Nesprin-1/-2: Roles in nuclear envelope organisation, myogenesis and dilated cardiomyopathy

Student thesis: Doctoral ThesisDoctor of Philosophy


Nesprins-1 and -2 are multi-isomeric scaffolding proteins. They are highly expressed in skeletal and cardiac muscle, and together with SUN (Sad1p/UNC84)-domain containing proteins and lamin A/C, forming the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex at the nuclear envelope (NE). Mutations in nesprin-1/-2 have previously been identified in patients with autosomal dominant Emery–Dreifuss muscular dystrophy (EDMD) as well as dilated cardiomyopathy (DCM).
In my study, three novel rare variants (R8272Q, S8381C, N8406K) in the C-terminus of the SYNE-1 (nesprin-1) gene were identified in 7 DCM patients by mutation screening. These mutants caused nuclear morphology defects, reduced lamin A/C and SUN2 staining at the NE and disrupted binding between nesprin-1/lamin/SUN. Nesprin-1 mutations were also associated with augmented activation of the ERK pathway in vitro and in hearts in vivo. During C2C12 myoblast differentiation, nesprin-1 protein levels increased concomitantly with kinesin light chain (KLC-1/2). GST pull-down assay showed that nesprin-1 and KCL-1/2 bind at the NE. Expression of nesprin-1 mutants in C2C12 cells caused defects in myoblast differentiation and fusion associated with dysregulation of myogenic regulatory factors and disruption of the nesprin-1 and KLC-1/2 interaction. Furthermore, expression of nesprin-1α2 WT and mutants in zebrafish embryos caused heart developmental and conduction defects that varied in severity. In addition, a novel cardiac specific dominant negative nesprin-2 KASH (Klarsicht/ANC-1/Syne-1 homology) transgenic (Tg) mouse model was generated. Data showed overexpression of KASH domain caused disruption of NE-LINC complex and induced a hypertrophic response with activated fetal gene re-expression in Tg mice at the basal line, which was exacerbated when subjected to pathological hemodynamic stress.
These findings support roles for nesprin-1/-2 in nuclear organisation and myogenesis, which may uncover a novel mechanism whereby disruption of the NE-LINC complex may contribute to the pathogenesis of DCM.
Date of Award1 Mar 2019
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorQiuping Zhang (Supervisor) & Cathy Shanahan (Supervisor)

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