Biology subjects

Robbe, Z. L.

Publications and source records attributed to Robbe, Z. L..

3 recordsLinked to original sources

bioRxiv2026

T cell-derived IFNγ instructs ECM crosslinking by cardiac fibroblasts through LOXL3 in experimental cardiometabolic HFpEF

BackgroundHeart failure with preserved ejection fraction (HFpEF) is a major clinical challenge characterized by diastolic dysfunction. Left ventricular stiffening and inflammation are hallmarks of HFpEF, yet the contribution of extracellular matrix (ECM) stiffness and the immune-stromal mechanisms driving ECM stiffening in cardiometabolic HFpEF remain poorly understood. MethodsWe used the murine "2-hit model" of cardiometabolic HFpEF, in which the combination of high fat diet and hypertension induced by L-NAME causes diastolic dysfunction. We evaluated diastolic function by echocardiography and ECM mechanics by uniaxial tensile testing of decellularized cardiac tissue. Functional in vivo studies included genetic depletion of T cells, interferon-{gamma} (IFN{gamma}) knockout mice, and pharmacological lysyl oxidase inhibition. We combined co-cultures of CD4+ T cells and cardiac fibroblasts (CFB) with mechanical testing of cardiac ECM and molecular biology to elucidate cellular and molecular mechanisms. ResultsLeft ventricular ECM stiffness strongly correlated with impaired diastolic function in experimental cardiometabolic HFpEF. Cardiac CD4 T cell infiltration was required for ECM stiffening and upregulation of lysyl oxidase enzymes in CFB. CD4+ T cell-derived IFN{gamma} was both necessary and sufficient to induce LOXL3 in CFB, which increased ECM stiffness in vitro. Mechanistically, IFN{gamma} signaling activated hypoxia-inducible factor-1 (HIF1) in CFB, driving LOXL3 expression and subsequent collagen crosslinking. Genetic or pharmacologic disruption of this IFN{gamma}-HIF1-LOXL3 axis in vivo attenuated adverse ECM remodeling and improved diastolic function. ConclusionsCD4 T cells promote pathological ECM stiffening in cardiometabolic HFpEF through IFN{gamma}-mediated, LOXL3-dependent ECM crosslinking by CFB. Targeting this immune-stromal pathway may offer a novel therapeutic strategy for HFpEF.

pathology↗

bioRxiv2021

CHD4 is recruited by GATA4 and NKX2-5 silencers to repress non-cardiac gene programs in the developing heart

The Nucleosome Remodeling and Deacetylase (NuRD) complex is one of the central chromatin remolding complexes that mediate gene repression. NuRD is essential for numerous developmental events, including heart development. Clinical and genetic studies have provided direct evidence for the role of chromodomain helicase DNA-binding protein 4 (CHD4), the catalytic component of NuRD, in congenital heart disease (CHD), including atrial and ventricular septal defects. Further, it has been demonstrated that CHD4 is essential for mammalian cardiomyocyte formation and function. A key unresolved question is how CHD4/NuRD is localized to specific cardiac targets genes, as neither CHD4 nor NuRD can directly bind DNA. Here, we coupled a bioinformatics-based approach with mass spectrometry analyses to demonstrate that CHD4 interacts with the core cardiac transcription factors GATA4, NKX2-5 and TBX5 during embryonic heart development. Using transcriptomics and genome-wide occupancy data, we have characterized the genomic landscape of GATA4, NKX2-5 and TBX5 repression and defined the direct cardiac gene targets of GATA4-CHD4, NKX2-5-CHD4 and TBX5-CHD4 complexes. These data were used to identify putative cis-regulatory elements regulated controlled by these complexes. We genetically interrogated two of these silencers in vivo, Acta1 and Myh11. We show that deletion of these silencers leads to inappropriate skeletal and smooth muscle gene mis-expression, respectively, in the embryonic heart. These results delineate how CHD4/NuRD is localized to specific cardiac loci and explicates how mutations in the broadly expressed CHD4 protein lead to cardiac specific disease states.

genomics↗

bioRxiv2020

Cardiac Sex Differences are Established Prior to Gonad Formation

Male and female disease states differ in their prevalence, treatment responses, and survival rates. In cardiac disease, women almost uniformly fare far worse than men. Though sex plays a critical role in cardiac disease, the mechanisms underlying sex differences in cardiac homeostasis and disease remain unexplained. Here, in adult and embryonic hearts we reveal sex-specific transcriptomes and proteomes and show that cardiac sex differences are predominately accounted for by post-transcriptional mechanisms. We found differential expression of male-female proteins in the cardiomyocytes. Using a quantitative proteomics-based approach, we characterized differential sex-specific enriched cardiac proteins, protein complexes, and biological sex processes in the context of global genetic diversity of the Collaborative Cross, an established surrogate for human diversity. We also found that sex differences in cardiac protein expression are established by both hormonal and sex chromosomal mechanisms. We have demonstrated the onset of sex-biased protein expression and discovered that sex disparities in heart tissue occur at the earliest stages of heart development at a period that preceeds mammalian gonadal development. Collectively, these findings may explain why congenital heart disease, a leading cause of death whose origin is often developmental, is sex biased. Our results reveal molecular foundations for differences in cardiac tissue that underlie sex disparities in health, disease, and treatment outcomes.

developmental biology↗