Publications by authors named "James D Hocker"

Matrix remodeling outcomes largely dictate patient survival post myocardial infarction. Moreover, human-restricted noncoding regulatory elements have been shown to worsen fibrosis, but their mechanism of action remains elusive. Here, we demonstrate, using induced pluripotent stem cell-derived cardiac fibroblasts (iCFs), that inflammatory ligands abundant in the remodeling heart after infarction activate AP-1 transcription factor signaling pathways resulting in fibrotic responses.

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Although the importance of genome organization for transcriptional regulation of cell-fate decisions and function is clear, the changes in chromatin architecture and how these impact effector and memory CD8 T cell differentiation remain unknown. Using Hi-C, we studied how genome configuration is integrated with CD8 T cell differentiation during infection and investigated the role of CTCF, a key chromatin remodeler, in modulating CD8 T cell fates through CTCF knockdown approaches and perturbation of specific CTCF-binding sites. We observed subset-specific changes in chromatin organization and CTCF binding and revealed that weak-affinity CTCF binding promotes terminal differentiation of CD8 T cells through the regulation of transcriptional programs.

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As we age, structural changes contribute to progressive decline in organ function, which in the heart act through poorly characterized mechanisms. Taking advantage of the short lifespan and conserved cardiac proteome of the fruit fly, we found that cardiomyocytes exhibit progressive loss of Lamin C (mammalian Lamin A/C homologue) with age, coincident with decreasing nuclear size and increasing nuclear stiffness. Premature genetic reduction of Lamin C phenocopies aging's effects on the nucleus, and subsequently decreases heart contractility and sarcomere organization.

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Since the initial isolation of human embryonic stem cells and subsequent discovery of reprogramming methods for somatic cells, thousands of protocols have been developed to create each of the hundreds of cell types found in-vivo with significant focus on disease-prone systems, e.g., cardiovascular.

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Current catalogs of regulatory sequences in the human genome are still incomplete and lack cell type resolution. To profile the activity of gene regulatory elements in diverse cell types and tissues in the human body, we applied single-cell chromatin accessibility assays to 30 adult human tissue types from multiple donors. We integrated these datasets with previous single-cell chromatin accessibility data from 15 fetal tissue types to reveal the status of open chromatin for ∼1.

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Misregulated gene expression in human hearts can result in cardiovascular diseases that are leading causes of mortality worldwide. However, the limited information on the genomic location of candidate cis-regulatory elements (cCREs) such as enhancers and promoters in distinct cardiac cell types has restricted the understanding of these diseases. Here, we defined >287,000 cCREs in the four chambers of the human heart at single-cell resolution, which revealed cCREs and candidate transcription factors associated with cardiac cell types in a region-dependent manner and during heart failure.

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Article Synopsis
  • The study investigates the role of CTCF, in collaboration with cohesin, in shaping chromatin structure and gene regulation during the differentiation of mouse embryonic stem cells into neural precursor cells.
  • Researchers found that CTCF binding at promoters is crucial for maintaining enhancer-promoter interactions, which significantly impact gene expression, particularly for genes reliant on long-distance enhancers.
  • The loss of CTCF binding led to reduced transcription and enhancer-promoter contacts, but restoring CTCF at promoters reinstated these interactions, highlighting its essential role in regulating over 2,000 genes across different adult tissues.
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Article Synopsis
  • T cell senescence and exhaustion limit the effectiveness of cancer immunotherapy.
  • The study demonstrates that miR-155 boosts CD8 T cell function against tumors by preventing senescence and exhaustion through the suppression of certain differentiation drivers.
  • It highlights a key mechanism involving miR-155, Phf19, and the Polycomb repressor complex 2 (PRC2) that together help maintain CD8 T cell activity and differentiation, suggesting potential for enhancing cancer treatments through epigenetic strategies.
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Stem cells are maintained by transcriptional programs that promote self-renewal and repress differentiation. Here, we found that the transcription factor c-Myb was essential for generating and maintaining stem cells in the CD8 T cell memory compartment. Following viral infection, CD8 T cells lacking Myb underwent terminal differentiation and generated fewer stem cell-like central memory cells than did Myb-sufficient T cells.

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Long-lived, self-renewing, multipotent T memory stem cells (TSCM) can trigger profound and sustained tumor regression but their rareness poses a major hurdle to their clinical application. Presently, clinically compliant procedures to generate relevant numbers of this T-cell population are undefined. Here, we provide a strategy for deriving large numbers of clinical-grade tumor-redirected TSCM starting from naive precursors.

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Adoptive T cell-based immunotherapies can mediate complete and durable regressions in patients with advanced cancer, but current response rates remain inadequate. Maneuvers to improve the fitness and antitumor efficacy of transferred T cells have been under extensive exploration in the field. Small non-coding microRNAs have emerged as critical modulators of immune system homeostasis and T cell immunity.

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