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Principal Investigator: Yifang Xie
Organization: UNIV OF NORTH CAROLINA CHAPEL HILL
Fiscal Year: 2024
Award: $106,201
Funding agency: National Heart Lung and Blood Institute
Project Summary
Heart attacks, or myocardial infarctions (MI), remain a leading cause of death worldwide. As adult human hearts
have limited regenerative capacity, cardiomyocytes (CMs) lost after MI are replaced by fibrotic scar tissue,
leading to cardiac dysfunction and often heart failure. A promising approach to replace lost CMs is direct
reprogramming of cardiac fibroblasts (CFs) into induced cardiomyocyte-like cells (iCMs) using the specific
cardiac lineage transcription factors Mef2c, Gata4 and Tbx5 (MGT). Over the last decade, considerable progress
has been made in understanding the transcriptional and epigenetic regulation of iCM generation. However, post-
transcriptional processes, including translation and mRNA modification, are also important to regulate gene
expression. Post-transcriptional regulators have recently been shown to play critical roles in cell fate
determination, but their roles in direct cardiac reprogramming are largely unknown. Recently, Dr. Xie identified
the RNA binding protein Ybx1 and the m6a reader Igf2bp1 as critical post-transcriptional barriers to iCM induction.
Excitingly, upon removing Ybx1, a single factor, Tbx5, could successfully reprogram fibroblasts into iCMs. Thus,
in Aim 1, Dr. Xie will use ChIP-seq and ATAC-seq to characterize the mechanisms by which the innovative
cocktail Tbx5+siYbx1 generates iCMs. Then, taking advantage of the reduced cargo size of this cocktail, Dr. Xie
will develop a clinically relevant lipid nanoparticle-mRNA delivery system to achieve in vivo iCM conversion in a
mouse MI model. Post-transcriptional mRNA m6a methylation is another regulator of gene expression important
in cell fate maintenance. In addition to serving as a barrier to cardiac reprogramming, Dr. Xie found that the m6a
binding protein, Igf2bp1, formed cellular granules in CFs. She, therefore, hypothesizes that Igf2bp1 sequesters
or otherwise regulates the stability of m6a mRNAs in CFs by regulating cellular RNP granule dynamics and that
loss of Igf2bp1 leads to a shift in mRNA metabolism promoting cardiac fate conversion. To test these hypotheses,
aim 2 is to identify m6a alternations associated with iCM generation, map precise RNA binding sites of Igf2bp1
and elucidate the underlying mechanism through which Igf2bp1-mediated cellular granule formation regulates
the induction of iCMs. The proposed work will not only fill critical gaps in our mechanistic understanding of how
post-transcriptional regulation impacts cardiac fate conversion, but also advance iCM reprogramming closer to
therapeutic application through the development of an LNP-mRNA delivery system. With an excellent mentoring
team and a stimulating research environment at UNC Chapel Hill, Dr. Xie will learn cutting-edge techniques and
hone her professional skills, which will provide a solid foundation for her future research in studying the
mechanisms of cardiovascular disease and to use insights from this work to develop novel therapies to improve
patients’ lives. This K99/R00 award will support the development of her unique and comprehensive research
program and catalyze the transition to independence.
Terms: <21+ years old><ATAC sequencing><ATAC-seq><ATACseq><Abscission><Adult><Adult Human><Affect><Area><Assay for Transposase-Accessible Chromatin using sequencing><Award><Basal Transcription Factor><Basal transcription factor genes><Binding Proteins><Binding Sites><Body Tissues><Cardiac><Cardiac Muscle Cells><Cardiac Myocytes><Cardiac infarction><Cardiocyte><Cardiovascular><Cardiovascular Body System><Cardiovascular Diseases><Cardiovascular Organ System><Cardiovascular system><Cause of Death><Cell Body><Cell Reprogramming><Cells><ChIP Sequencing><ChIP-seq><ChIPseq><Chromatin><Cicatrix><Combining Site><Cytoplasmic Granules><DNA Binding><DNA Binding Interaction><DNA bound><Data><Development><Disease Progression><Environment><Excision><Exhibits><Extirpation><Fibroblasts><Foundations><Future><GATA binding protein 4><GATA4><GATA4 gene><GATA4 transcription factor><Gene Expression><General Transcription Factor Gene><General Transcription Factors><Generations><Goals><Heart><Heart Muscle Cells><Heart Vascular><Heart failure><Heart myocyte><Induced Cardiomyocytes><Infarction><Intermediary Metabolism><Investigators><Learning><Ligand Binding Protein><Ligand Binding Protein Gene><Maintenance><Maps><Mediating><Mentors><Messenger RNA><Metabolic Processes><Metabolism><Methylation><Mice><Mice Mammals><Modeling><Modification><Molecular><Murine><Mus><Myocardial Infarct><Myocardial Infarction><Myocardial depression><Myocardial dysfunction><Nature><Patients><Play><Post-Transcriptional Control><Post-Transcriptional Regulation><Process><Protein Binding><RNA Binding><RNA bound><RNA-Binding Proteins><Reactive Site><Reader><Regenerative capacity><Regulation><Regulator Genes><Removal><Research><Research Personnel><Researchers><Ribo-seq><Role><Scars><Solid><Stem cell pluripotency><Surgical Removal><Techniques><Testing><Therapeutic><Time><Tissues><Transcription Factor Proto-Oncogene><Transcription Process><Transcription Regulation><Transcription factor genes><Transcriptional Control><Transcriptional Regulation><Transcriptional Regulatory Elements><Translational Regulation><Translations><United States><Work><adulthood><assay for transposase accessible chromatin followed by sequencing><assay for transposase accessible chromatin seq><assay for transposase accessible chromatin sequencing><assay for transposase-accessible chromatin with sequencing><barrier to translation><bound protein><cardiac dysfunction><cardiac failure><cardiac infarct><cardiac regeneration><cardiac repair><cardiomyocyte><cardiovascular disorder><career><cellular reprogramming><chromatin immunoprecipitation-sequencing><circulatory system><clinical applicability><clinical application><clinical implementation><clinical relevance><clinical translation><clinically relevant><clinically translatable><coronary attack><coronary infarct><coronary infarction><deliver mRNA><deliver messenger RNA><delivery system for mRNA><developmental><epigenetic regulation><genome scale><genome-wide><genomewide><granule><heart attack><heart dysfunction><heart infarct><heart infarction><heart regeneration><heart repair><human disease><icardiomyocytes><improved><in vivo><induced cardiac myocytes><infarct><innovate><innovation><innovative><insight><interest><lipid based nanoparticle><lipid nanoparticle><loss of function><mRNA><mRNA delivery><meeting><meetings><messenger RNA delivery><mutant><new drug treatments><new drugs><new pharmacological therapeutic><new therapeutics><new therapy><next generation therapeutics><novel drug treatments><novel drugs><novel pharmaco-therapeutic><novel pharmacological therapeutic><novel therapeutics><novel therapy><obstacle to translation><overexpress><overexpression><post-transcriptional gene regulation><posttranscriptional><posttranscriptional control><posttranscriptional regulation><programs><regeneration ability><regeneration capacity><regenerative><regulatory gene><repair strategy><resection><ribosome footprint profiling><ribosome profiling><scRNA-seq><single cell RNA-seq><single cell RNAseq><single cell expression profiling><single cell transcriptomic profiling><single-cell RNA sequencing><skills><social role><trans acting element><transcription factor><transcriptome profiling><transcriptomic profiling><translation><translation barrier><translation obstacle><translational barrier><translational obstacle>