YuanYuan Dai

All Publications

• Generation of two induced pluripotent stem cell lines from patients with Williams syndrome. Stem cell research Dai, Y., Zhu, W., Flores Banuelos, A. G., Li, J., Mukherjee, S., Algaze, C., Wu, J. C. 2024; 78: 103460

  Abstract

  Williams syndrome (WS) is a relatively rare genetic disorder. It arises from a microdeletion in chromosome 7q11.23, resulting in the loss of one copy of more than 20 genes. Disorders in multiple systems, including cardiovascular and nervous systems, occur in patients with WS. Here, we generated two human induced pluripotent stem cell (iPSC) lines from WS patients. Both lines expressed pluripotency markers at gene and protein levels. They possessed normal karyotypes and the potential to differentiate into three germ layers. They serve as a useful tool to study disease mechanism, test drugs, and identify promising therapeutics for patients with WS.

  View details for DOI 10.1016/j.scr.2024.103460

  View details for PubMedID 38861775

• An Alternative Mechanism of Subcellular Iron Uptake Deficiency in Cardiomyocytes. Circulation research Dai, Y., Ignatyeva, N., Xu, H., Wali, R., Toischer, K., Brandenburg, S., Lenz, C., Pronto, J., Fakuade, F. E., Sossalla, S., Zeisberg, E. M., Janshoff, A., Kutschka, I., Voigt, N., Urlaub, H., Rasmussen, T. B., Mogensen, J., Lehnart, S. E., Hasenfuss, G., Ebert, A. 2023; 133 (2): e19-e46

  Abstract

  Systemic defects in intestinal iron absorption, circulation, and retention cause iron deficiency in 50% of patients with heart failure. Defective subcellular iron uptake mechanisms that are independent of systemic absorption are incompletely understood. The main intracellular route for iron uptake in cardiomyocytes is clathrin-mediated endocytosis.We investigated subcellular iron uptake mechanisms in patient-derived and CRISPR/Cas-edited induced pluripotent stem cell-derived cardiomyocytes as well as patient-derived heart tissue. We used an integrated platform of DIA-MA (mass spectrometry data-independent acquisition)-based proteomics and signaling pathway interrogation. We employed a genetic induced pluripotent stem cell model of 2 inherited mutations (TnT [troponin T]-R141W and TPM1 [tropomyosin 1]-L185F) that lead to dilated cardiomyopathy (DCM), a frequent cause of heart failure, to study the underlying molecular dysfunctions of DCM mutations.We identified a druggable molecular pathomechanism of impaired subcellular iron deficiency that is independent of systemic iron metabolism. Clathrin-mediated endocytosis defects as well as impaired endosome distribution and cargo transfer were identified as a basis for subcellular iron deficiency in DCM-induced pluripotent stem cell-derived cardiomyocytes. The clathrin-mediated endocytosis defects were also confirmed in the hearts of patients with DCM with end-stage heart failure. Correction of the TPM1-L185F mutation in DCM patient-derived induced pluripotent stem cells, treatment with a peptide, Rho activator II, or iron supplementation rescued the molecular disease pathway and recovered contractility. Phenocopying the effects of the TPM1-L185F mutation into WT induced pluripotent stem cell-derived cardiomyocytes could be ameliorated by iron supplementation.Our findings suggest that impaired endocytosis and cargo transport resulting in subcellular iron deficiency could be a relevant pathomechanism for patients with DCM carrying inherited mutations. Insight into this molecular mechanism may contribute to the development of treatment strategies and risk management in heart failure.

  View details for DOI 10.1161/CIRCRESAHA.122.321157

  View details for PubMedID 37313752

• Integrated Ca2+ flux and AFM force analysis in human iPSC-derived cardiomyocytes. Biological chemistry Malkovskiy, A. V., Ignatyeva, N., Dai, Y., Hasenfuss, G., Rajadas, J., Ebert, A. 2020

  Abstract

  We developed a new approach for combined analysis of calcium (Ca2+) handling and beating forces in contractile cardiomyocytes. We employed human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from dilated cardiomyopathy (DCM) patients carrying an inherited mutation in the sarcomeric protein troponin T (TnT), and isogenic TnT-KO iPSC-CMs generated via CRISPR/Cas9 gene editing. In these cells, Ca2+ handling as well as beating forces and-rates using single-cell atomic force microscopy (AFM) were assessed. We report impaired Ca2+ handling and reduced contractile force in DCM iPSC-CMs compared to healthy WT controls. TnT-KO iPSC-CMs display no contractile force or Ca2+ transients but generate Ca2+ sparks. We apply our analysis strategy to Ca2+ traces and AFM deflection recordings to reveal maximum rising rate, decay time, and duration of contraction with a multi-step background correction. Our method provides adaptive computing of signal peaks for different Ca2+ flux or force levels in iPSC-CMs, as well as analysis of Ca2+ sparks. Moreover, we report long-term measurements of contractile force dynamics on human iPSC-CMs. This approach enables deeper and more accurate profiling of disease-specific differences in cardiomyocyte contraction profiles using patient-derived iPSC-CMs.

  View details for DOI 10.1515/hsz-2020-0212

  View details for PubMedID 33108335

• Troponin destabilization impairs sarcomere-cytoskeleton interactions in iPSC-derived cardiomyocytes from dilated cardiomyopathy patients. Scientific reports Dai, Y., Amenov, A., Ignatyeva, N., Koschinski, A., Xu, H., Soong, P. L., Tiburcy, M., Linke, W. A., Zaccolo, M., Hasenfuss, G., Zimmermann, W. H., Ebert, A. 2020; 10 (1): 209

  Abstract

  The sarcomeric troponin-tropomyosin complex is a critical mediator of excitation-contraction coupling, sarcomeric stability and force generation. We previously reported that induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from patients with a dilated cardiomyopathy (DCM) mutation, troponin T (TnT)-R173W, display sarcomere protein misalignment and impaired contractility. Yet it is not known how TnT mutation causes dysfunction of sarcomere microdomains and how these events contribute to misalignment of sarcomeric proteins in presence of DCM TnT-R173W. Using a human iPSC-CM model combined with CRISPR/Cas9-engineered isogenic controls, we uncovered that TnT-R173W destabilizes molecular interactions of troponin with tropomyosin, and limits binding of PKA to local sarcomere microdomains. This attenuates troponin phosphorylation and dysregulates local sarcomeric microdomains in DCM iPSC-CMs. Disrupted microdomain signaling impairs MYH7-mediated, AMPK-dependent sarcomere-cytoskeleton filament interactions and plasma membrane attachment. Small molecule-based activation of AMPK can restore TnT microdomain interactions, and partially recovers sarcomere protein misalignment as well as impaired contractility in DCM TnT-R173W iPSC-CMs. Our findings suggest a novel therapeutic direction targeting sarcomere- cytoskeleton interactions to induce sarcomere re-organization and contractile recovery in DCM.

  View details for DOI 10.1038/s41598-019-56597-3

  View details for PubMedID 31937807

  View details for PubMedCentralID PMC6959358

• Proteasome-Dependent Regulation of Distinct Metabolic States During Long-Term Culture of Human iPSC-Derived Cardiomyocytes. Circulation research Ebert, A. n., Joshi, A. U., Andorf, S. n., Dai, Y. n., Sampathkumar, S. n., Chen, H. n., Li, Y. n., Garg, P. n., Toischer, K. n., Hasenfuβ, G. n., Mochly Rosen, D. n., Wu, J. C. 2019

  Abstract

  The immature presentation of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) is currently a challenge for their application in disease modeling, drug screening, and regenerative medicine. Long-term culture is known to achieve partial maturation of iPSC-CMs. However, little is known about the molecular signaling circuitries that govern functional changes, metabolic output, and cellular homeostasis during long-term culture of iPSC-CMs.We aimed to identify and characterize critical signaling events that control functional and metabolic transitions of cardiac cells during developmental progression, as recapitulated by long-term culture of iPSC-CMs.We combined transcriptomic sequencing with pathway network mapping in iPSC-CMs that were cultured until a late time point, day 200 (D200), in comparison to a medium time point, day 90 (D90), and an early time point, day 30 (D30). Transcriptomic landscapes of long-term cultured iPSC-CMs allowed mapping of distinct metabolic stages during development of maturing iPSC-CMs. Temporally divergent control of mitochondrial metabolism was found to be regulated by cAMP/protein kinase A (PKA)- and proteasome-dependent signaling events. The PKA/proteasome-dependent signaling cascade was mediated downstream by heat shock protein 90 (Hsp90), which in turn modulated mitochondrial respiratory chain proteins and their metabolic output. During long-term culture, this circuitry was found to initiate upregulation of iPSC-CM metabolism, resulting in increased cell contractility that reached a maximum at the D200 time point.Our results reveal a PKA/proteasome- and Hsp90-dependent signaling pathway that regulates mitochondrial respiratory chain proteins and determines cardiomyocyte energy production and functional output. These findings provide deeper insight into signaling circuitries governing metabolic homeostasis in iPSC-CMs during developmental progression.

  View details for DOI 10.1161/CIRCRESAHA.118.313973

  View details for PubMedID 31104567