The main objective of our research activities is to explore fundamental cardiovascular biology. Our team is specifically interested on the function of the transcriptional and post-transcriptional machinery of the developing, diseased and normal myocardium. A special focus is placed on evolutionary conserved endogenous mechanisms including the nuclear Wnt signaling complexes and their role in tissue remodeling. Our models comprise preclinical animal and humanized models. We aim to exploit our gained knowledge and expertise to define disease-specific and personalized therapeutic options and to ultimately establish CRISPR-based endogenous transcription engineering to therapeutically program a homoeostatic heart. This is feasible by embedding the process in a leading, cutting-edge cardiovascular research environment using state-of-the-art technology.
The cardiac transcriptional Wnt-complex
Transgenic activation of Wnt/β-catenin signaling results in cardiac dysfunction.
Accordingly, preserved function after ischemic and pressure overload was observed upon inhibition of Wnt/b-catenin signaling in the adult mouse heart.
Our team has demonstrated that aberrantly high Wnt/β−catenin/TCF-mediated activity in adult cardiomyocyte,
triggers transcriptional reprogramming (dedifferentiation), development processes activation involving cell cycle;
multi-nucleation and a secretome that activate a developmental vascular cell remodeling program culminating in heart failure.
We aim to unravel Wnt-dependent mechanisms instructing cardiovascular tissue formation, heart homeostasis and remodeling in a cell-
and context-specific manner. Moreover, Transcription factor 7-like 2 (TCF7L2) is a major determinant of downstream Wnt target gene expression and
is tightly controlled by tissue specific inhibitors. Thus, the Wnt nuclear pathway is a promising pharmacological target candidate for modulating
the initiation of maladaptive heart remodeling and heart failure progression. However, pharmacological targeting of the Wnt pathway is challenging,
because of its central role in many tissues. We have recently identified KLF15 as a cardiomyocyte specific regulator of Wnt/β-catenin signaling as well as
defined its interaction as a tripartite complex associated with chromatin and the regulation of chromatin state.
We are resolving the Wnt/β-catenin/KLF5 complex structure and stability as the basis for drug design.
KLF15 and GATA4 are cardiac specific factors controlling β-catenin/TCF7L27 transcriptional activation (Noack et al. 2012; Iyer et al 2018; Noack, Iyer et al. 2019).
Engineering synthetic transcription to control cell behavior
In order to find therapeutic concepts recovering the heart from damage,
manipulation of multiple targets affecting gene regulatory networks (GRN) is required.
In order to design such a therapy, fundamental cardiomyocyte biology and its cellular and
molecular networks embedded in its in vivo natural environment need to be addressed.
More importantly, this need to be elucidated in a disease-context-specific manner.
CRISPR/Cas9 technology has been adapted to lose its catalytic activity completely and fused to transcriptional activators (CRISPRa) or
repressors (CRISPRi) to modulate gene expression. CRISPRa / i has overcome limitations of previous transcriptional modulation methods.
Importantly, it can be designed to create unprecedented levels of control offering a multiplexing possibility at the same time.
Multiplexing allows modulating multiple genes within the same pathway thus potentiating a synergetic effect of tightly regulated endogenous GRNs.
More importantly, the catalytic inactive Cas9 has limited unwanted effect leaving the genome unaffected, highly desired for therapeutic applications.
All these elements will be exploited in our studies for deciphering complex endogenous mechanisms of regulation in cardiomyocyte disease biology.
We generated a heart specific CRISPR/dCas9-based approach combined with AAV9-mediated gRNA delivery, a very versatile new approach to tailor gene expression in theostnatal heart (Schoger et al 2019).
We generated CRISPRa/I human induced pluripotent stem cell (hiPSC) lines that can be employed for sustained endogenous gene activation and silencing in all human hiPSC-derived cell types (Schoger et al 2020).
Our methodology is based on biochemical, epigenetic, transcriptional and functional investigation of novel identified factors using classical
mouse knockout strategies combined with mouse embryo electroporation (EP) culture, tissue explants and human induced pluripotent stem cells (IPSCs)
and finally tissue engineered (in coll. With Prof. Zimmermann´s team). The used of human samples (heart biopsies and serum) are included
to validated human relevant mechanisms. Our group has expanded the CRISPR-toolbox in mouse and in IPSCs. CRISPR/Cas9-based technology is
used for gene editing (knockout and knockin) as well as for transcriptional modulation in vitro in in vivo.
Illustrations: Servier Medical Art (https://smart.servier.com).