The research, led by Kwonho Hong of Konkuk University in Seoul together with an international team spanning institutions in Korea, China, and the United States, focused on a deceptively simple question: how do transcription factors gain access to the DNA they need to control during the critical window of lymphatic development? Transcription factors are the proteins that bind specific DNA sequences and switch genes on or off, but they can only reach their targets when the genome’s packaging material, chromatin, is open and accessible. The study reveals that INO80, a large molecular machine that slides and repositions nucleosomes, is what keeps those access points properly configured in lymphatic endothelial cells.

Using chromatin accessibility profiling in embryonic lymphatic endothelial cells, the team mapped the landscape of open chromatin between embryonic days 10.5 and 12.5, a period when the lymphatic vasculature is being established. They found a striking increase in accessibility at regulatory motifs for ETS family transcription factors, a group of well-known drivers of endothelial identity, and for YY1, a versatile transcriptional regulator that also happens to be a component of the INO80 complex itself. This temporal opening of the genome suggested that the cell was actively preparing its regulatory elements to receive developmental instructions, and that INO80 was positioned at the heart of that preparation.

To test whether INO80 was merely present or genuinely essential, the researchers deleted the Ino80 gene specifically in endothelial cells of mouse embryos. The result was catastrophic for the developing lymphatic system. Animals lacking INO80 in their endothelium displayed lethal lymphatic defects, including dermal edema, a swelling of the skin caused by fluid that the compromised lymphatic vessels could no longer drain. The lymphatic vessels of mutant embryos filled with blood, a hallmark phenotype of defective lymphatic-venous separation, and the lymphatic networks of the heart and mesentery were hypoplastic, meaning they failed to grow to their proper size and complexity.

At the molecular level, the consequences of INO80 loss were equally dramatic. Gene expression analysis revealed widespread dysregulation of genes controlling cell adhesion, cell migration, and vessel formation, the very processes that lymphatic endothelial cells must execute with precision to build a functional vascular network. The finding underscores a principle increasingly recognized in developmental biology: transcription factors alone are not sufficient to run a differentiation program. Without the chromatin remodeling machinery that maintains the correct accessibility landscape, even the right transcription factors cannot execute the right instructions at the right time.

The study went further, asking where INO80 actually sits in the genome of developing lymphatic endothelial cells. Mapping INO80-bound regions revealed a strong enrichment for ETS transcription factor motifs, and these occupied sites were preferentially associated with endothelial developmental genes. This genomic colocalization pointed to a functional partnership: INO80 does not act randomly across the genome but concentrates at regulatory elements where ETS factors operate, effectively shaping the chromatin terrain on which those factors depend.

One of the most intriguing discoveries involved the transcription factor ERG, an ETS family member with established roles in endothelial biology. The researchers observed that INO80 peaks containing ERG motifs were preferentially linked to angiogenic genes, genes that drive blood vessel growth, and that these same genes became dysregulated after INO80 loss. The data suggest a model in which INO80 and ERG collaborate to restrain aberrant angiogenic gene expression in lymphatic endothelial cells. In other words, INO80 is not simply an activator of the lymphatic program; it also appears to act as a gatekeeper, preventing lymphatic vessels from inappropriately adopting blood vessel-like behaviors during development.

This dual role, enabling lymphatic identity while suppressing inappropriate angiogenic programs, offers a fresh perspective on how chromatin remodelers contribute to cell fate decisions. The INO80 complex, first characterized in yeast as a regulator of nucleosome positioning and DNA repair, has emerged in vertebrates as a versatile player in transcriptional control. The new findings place it squarely within the epigenetic toolkit that lymphatic endothelial cells use to navigate their differentiation journey, alongside better-studied regulators such as the master lymphatic transcription factor PROX1 and the vascular ETS factors.

The clinical implications are potentially far-reaching. Lymphedema affects hundreds of millions of people worldwide, and congenital lymphatic malformations often trace back to defects in the same developmental pathways explored in this study. If INO80-mediated chromatin remodeling proves to be a conserved requirement for lymphatic specification in humans, it could open new avenues for understanding inherited lymphatic disorders and for designing regenerative strategies that coax lymphatic endothelial cells into forming functional vessels. Chromatin remodelers are also increasingly pursued as drug targets in oncology, and lymphatic vessels are a known route for cancer metastasis, adding another layer of therapeutic relevance.

For now, the study stands as a compelling demonstration that the three-dimensional accessibility of the genome is not a passive backdrop but an active, dynamically regulated feature of lymphatic development. By showing that INO80 shapes chromatin accessibility at ETS transcription factor-associated regulatory elements, the researchers have connected the epigenetic machinery to the transcriptional programs that build the lymphatic system, and they have revealed what happens when that connection breaks. As the field moves toward a complete mechanistic map of lymphatic vascular development, INO80 now occupies a prominent place on that map, a molecular architect whose work, though invisible to the naked eye, determines whether the body’s drainage network forms at all.

Subject of Research: INO80 chromatin remodeling in ETS transcription factor-mediated gene regulation during lymphatic endothelial cell development

Article Title: INO80 function in ETS transcription factor-mediated transcriptional programs in developing lymphatic endothelial cells

Article References: La, H., Yoo, H., Kwon, O., Thang, N. X., Moon, E.-H., Choi, D. Y., Park, C., Han, D. W., Lee, Y. J., Do, J. T., Lee, M. R., Song, H., Rhee, S., Hong, Y.-K., Jang, Y.-J., Choi, Y., & Hong, K. (2026). INO80 function in ETS transcription factor-mediated transcriptional programs in developing lymphatic endothelial cells. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06460-2

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06460-2

Keywords: INO80, lymphatic endothelial cells, chromatin remodeling, ETS transcription factors, ERG, YY1, lymphatic development, chromatin accessibility, epigenetics, gene regulation, angiogenesis, lymphedema