Biology subjects

Hoeksema, M. A.

Publications and source records attributed to Hoeksema, M. A..

5 recordsLinked to original sources

bioRxiv2026

A non-canonical EZH2/TRIM28 epigenetic axis drives heparan sulfate remodeling and melanoma metastasis

Melanoma progression and metastasis are driven not only by oncogenic alterations but also by epigenetic programs that dynamically remodel the tumor microenvironment. Heparan sulfate (HS) proteoglycans are key extracellular matrix components that integrate growth factor signaling, cell-matrix interactions, and migratory behavior by controlling ligand availability and receptor engagement, yet how chromatin-associated factors regulate HS remodeling in cancer remains poorly defined. Here, we identify the histone methyltransferase EZH2 as a key regulator of HS biosynthesis in melanoma. Integrated bioinformatic and genomic analyses revealed enrichment of EZH2 and additional Polycomb Repressive Complex (PRC) factors at regulatory regions of HS biosynthetic genes. CRISPR-mediated loss of EZH2 altered expression of multiple HS-modifying enzymes, most notably the secreted endosulfatases SULF1 and SULF2, resulting in enhanced HS 6-O sulfation and altered ligand binding at the cell surface. Unexpectedly, EZH2 promoted SULF1 expression through a methyltransferase-independent mechanism via a non-canonical interaction with TRIM28, whereas SULF2 was regulated through canonical PRC2-mediated repression. Functionally, SULF1 depletion impaired melanoma cell migration and invasion in vitro and reduced spontaneous metastasis in an orthotopic xenograft model. Together, these findings define an epigenetic axis linking chromatin regulation to extracellular glycan remodeling and identify HS-modifying enzymes as candidate targets to limit melanoma metastasis.

molecular biology↗

bioRxiv2025

Uncovering an unconventional JAK1/2-STAT3 branch in macrophage IFNγ signaling

Interferon-{gamma} (IFN{gamma}) is a key cytokine in immune activation, especially anti-viral responses and driver of macrophage activation. It classically signals via JAK1/2-mediated STAT1 homodimers. Here, we identify an alternative, non-canonical signaling component in which IFN{gamma} simultaneously also activates STAT3. Our results show that IFN{gamma} activates STAT3 rapidly and directly through JAK1 and JAK2. We provide the first evidence that STAT3 can form heterodimers with STAT1 in this context and demonstrate that STAT3 is co-recruited to a subset of IFN{gamma}-induced, STAT1-bound regulatory elements. While IFN{gamma} directly activates STAT3, our results reveal that its contribution to gene regulation is limited, indicating that STAT1 easily substitutes the STAT1-STAT3 heterodimer for STAT1 homodimers when STAT3 is absent. These findings uncover STAT3 as a new unconventional player in macrophage IFN{gamma} signaling, underscoring the complex and context-dependent nature of cytokine signaling networks.

immunology↗

bioRxiv2024

EPA induces an anti-inflammatory transcriptomic landscape in T cells implicating a pathway independent of triglyceride lowering in CVD risk reduction

A twice-daily dose of highly purified eicosapentaenoic acid (EPA) reduces the risk of atherosclerotic cardiovascular disease among patients with high triglycerides and either known cardiovascular disease or those at high risk for developing it. However, the process by which EPA exerts its beneficial effects remains poorly understood. Here, we show that EPA can induce an anti-inflammatory transcriptional profile in non-activated CD4+ T cells. We find that EPA-exposed CD4+ T cells downregulate immune response related genes, such as HLA-DRA, CD69, and IL2RA, while upregulating genes involved in oxidative stress prevention, such as NQO1. Furthermore, transcription footprint analysis based on ATAC-sequencing reveals downregulation of GATA3 and PU.1, key transcription factors in TH2 and TH9 differentiation, and upregulation of REV-ERB, an antagonist of TH17 differentiation. By in parallel examining T cell responses to oleic acid, a monounsaturated fatty acid, and palmitic acid, a saturated fatty acid, we find that both the intensity of the transcriptomic response and the involvement of anti-inflammatory pathways is highly specific for EPA. Thus, EPA can induce an anti-inflammatory transcriptomic landscape in CD4+ T cells, a process that may contribute to the unexpectedly strong beneficial effects of EPA on the risk of atherosclerotic cardiovascular disease in clinical trials.

genomics↗

bioRxiv2024

Oleic acid triggers CD4+ T cells to be metabolically rewired and poised to differentiate into proinflammatory T cell subsets upon activation

T cells are the most common immune cells in atherosclerotic plaques and the function of T cells can be altered by fatty acids. Here, we show that pre-exposure of CD4+ T cells to oleic acid, an abundant fatty acid linked to cardiovascular events, results in a preferential differentiation into pro-inflammatory subsets upon activation by upregulating core metabolic pathways. RNA-sequencing of non-activated CD4+ T cells revealed that oleic acid upregulates genes encoding enzymes responsible for cholesterol and fatty acid biosynthesis. Transcription footprint analysis linked this rewiring to the differentiation of pro-inflammatory subsets. Indeed, spectral flow cytometry showed that pre-exposure to oleic acid results in a skew toward IL-9, IL-17A, IL-5 and IL-13 producing T cells upon activation. Importantly, inhibition of either cholesterol or fatty acid biosynthesis abolishes this effect, suggesting a beneficial role for statins beyond cholesterol lowering. Taken together, fatty acids may affect inflammatory diseases by influencing T cell metabolism.

genomics↗

bioRxiv2020

Mechanisms underlying divergent responses of genetically distinct macrophages to IL-4

Mechanisms by which non-coding genetic variation influences gene expression remain only partially understood but are considered to be major determinants of phenotypic diversity and disease risk. Here, we evaluated effects of >50 million SNPs and InDels provided by five inbred strains of mice on the responses of macrophages to interleukin 4 (IL-4), a cytokine that plays pleiotropic roles in immunity and tissue homeostasis. Remarkably, of >600 genes induced >2-fold by IL-4 across the five strains, only 26 genes reached this threshold in all strains. By applying deep learning and motif mutation analyses to epigenetic data for macrophages from each strain, we identified the dominant combinations of lineage determining and signal-dependent transcription factors driving late enhancer activation. These studies further revealed mechanisms by which non-coding genetic variation influences absolute levels of enhancer activity and their dynamic responses to IL-4, thereby contributing to strain-differential patterns of gene expression and phenotypic diversity.

genomics↗