TY  - JOUR
A1  - Zink, Miriam
A1  - Seewald, Anne
A1  - Rohrbach, Mareike
A1  - Brodehl, Andreas
A1  - Liedtke, Daniel
A1  - Williams, Tatjana
A1  - Childs, Sarah J.
A1  - Gerull, Brenda
T1  - Altered expression of TMEM43 causes abnormal cardiac structure and function in zebrafish
JF  - International Journal of Molecular Sciences
N2  - Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disease caused by heterozygous missense mutations within the gene encoding for the nuclear envelope protein transmembrane protein 43 (TMEM43). The disease is characterized by myocyte loss and fibro-fatty replacement, leading to life-threatening ventricular arrhythmias and sudden cardiac death. However, the role of TMEM43 in the pathogenesis of ACM remains poorly understood. In this study, we generated cardiomyocyte-restricted transgenic zebrafish lines that overexpress eGFP-linked full-length human wild-type (WT) TMEM43 and two genetic variants (c.1073C>T, p.S358L; c.332C>T, p.P111L) using the Tol2-system. Overexpression of WT and p.P111L-mutant TMEM43 was associated with transcriptional activation of the mTOR pathway and ribosome biogenesis, and resulted in enlarged hearts with cardiomyocyte hypertrophy. Intriguingly, mutant p.S358L TMEM43 was found to be unstable and partially redistributed into the cytoplasm in embryonic and adult hearts. Moreover, both TMEM43 variants displayed cardiac morphological defects at juvenile stages and ultrastructural changes within the myocardium, accompanied by dysregulated gene expression profiles in adulthood. Finally, CRISPR/Cas9 mutants demonstrated an age-dependent cardiac phenotype characterized by heart enlargement in adulthood. In conclusion, our findings suggest ultrastructural remodeling and transcriptomic alterations underlying the development of structural and functional cardiac defects in TMEM43-associated cardiomyopathy.
KW  - TMEM43
KW  - arrhythmogenic cardiomyopathy
KW  - zebrafish
KW  - CRISPR/Cas9
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286025
SN  - 1422-0067
VL  - 23
IS  - 17
ER  - 
TY  - JOUR
A1  - Gmach, Philipp
A1  - Bathe-Peters, Marc
A1  - Telugu, Narasimha
A1  - Miller, Duncan C.
A1  - Annibale, Paolo
T1  - Fluorescence spectroscopy of low-level endogenous β-adrenergic receptor expression at the plasma membrane of differentiating human iPSC-derived cardiomyocytes
JF  - International Journal of Molecular Sciences
N2  - The potential of human-induced pluripotent stem cells (hiPSCs) to be differentiated into cardiomyocytes (CMs) mimicking adult CMs functional morphology, marker genes and signaling characteristics has been investigated since over a decade. The evolution of the membrane localization of CM-specific G protein-coupled receptors throughout differentiation has received, however, only limited attention to date. We employ here advanced fluorescent spectroscopy, namely linescan Fluorescence Correlation Spectroscopy (FCS), to observe how the plasma membrane abundance of the β\(_1\)- and β\(_2\)-adrenergic receptors (β\(_{1/2}\)-ARs), labelled using a bright and photostable fluorescent antagonist, evolves during the long-term monolayer culture of hiPSC-derived CMs. We compare it to the kinetics of observed mRNA levels in wildtype (WT) hiPSCs and in two CRISPR/Cas9 knock-in clones. We conduct these observations against the backdrop of our recent report of cell-to-cell expression variability, as well as of the subcellular localization heterogeneity of β-ARs in adult CMs.
KW  - GPCR
KW  - β-adrenergic receptors
KW  - hiPSC-CM
KW  - cardiomyocyte
KW  - fluorescence correlation spectroscopy
KW  - FCS
KW  - fluorescence
KW  - CRISPR/Cas9
KW  - differentiation
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-288277
SN  - 1422-0067
VL  - 23
IS  - 18
ER  -