# Development of pan-Expansion Microscopy to reveal mechanisms underlying epidermal differentiation

> **NIH NIH R21** · YALE UNIVERSITY · 2022 · $221,100

## Abstract

Summary
There is an increasing appreciation that mechanical signals play key roles in tissue homeostasis. This project
seeks to define the cellular and molecular mechanisms by which force transmission to the nucleus through Linker
of Nucleoskeleton and Cytoskeleton (LINC) complexes regulates differentiation using skin as a model system,
yielding insights into fundamental mechanisms in cell biology and mechanobiology. Central to this proposal is
the need for an imaging technology that is capable of 1) resolving specifically labeled nuclear features (e.g. a
genomic locus, specific histone modification, or proteins of interest), 2) in the context of the surrounding nuclear
morphology, 3) at a resolution approaching the size of nucleosomes (~10 nanometers). However, as no readily
accessible microscopy method currently meets all of these requirements, there is an urgent need for new imaging
techniques that allow researchers to visualize specific structures of interest in the unbiased nanoscale context
of the surrounding nuclear organization. We recently developed pan-Expansion Microcopy (pan-ExM), which
provides optical contrast equivalent to EM heavy-metal stains using standard confocal microscopy but remains
fully compatible with molecular techniques such as immunolabeling. In this project, we will 1), validate structural
preservation of the expanded nucleus in the epidermis when using the pan-ExM protocol by investigating the
integrity of the DNA, folding of the genome and nucleosome structure; and 2), apply pan-ExM to investigate how
LINC complex ablation impacts nuclear remodeling during epidermal differentiation. For the latter, we will test
how the folding and compartmentalization of the “epidermal differentiation complex” (EDC), a specialized region
of the genome housing over 60 epidermal differentiation genes, are altered in the absence of LINC complexes,
and explore how key chromatin factors in epidermal differentiation are recruited to (or removed from) the EDC
during epidermal differentiation. Our project will have high impact in two aspects: it will provide answers to the
fundamental question of how mechanical cues can be translated to alter gene expression in the epidermis,
thereby laying the groundwork for a larger research program. Second, pan-ExM represents a novel tool that will
accelerate research, particularly by dissemination of protocols validated in the epidermis to any interested
research lab, thereby providing a much-needed research tool that will allow researchers to systematically
investigate the connection between chromatin structure and function both in normal epidermal differentiation and
also in disease contexts.

## Key facts

- **NIH application ID:** 10539999
- **Project number:** 1R21AR081661-01
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Joerg Bewersdorf
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $221,100
- **Award type:** 1
- **Project period:** 2022-07-15 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10539999

## Citation

> US National Institutes of Health, RePORTER application 10539999, Development of pan-Expansion Microscopy to reveal mechanisms underlying epidermal differentiation (1R21AR081661-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10539999. Licensed CC0.

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