# Deciphering the Mechanism of Revertant Mosaicism and Cellular Competition in Ichthyosis with Confetti

> **NIH NIH F31** · YALE UNIVERSITY · 2021 · $30,891

## Abstract

PROJECT SUMMARY / ABSTRACT
Revertant mosaicism (RM) is a rare but naturally phenomenon wherein cells carrying disease-causing mutations
coexist with cells in which the mutation has been spontaneously replaced with a normal allele. Ichthyosis with
confetti (IWC) is a rare skin disorder that commonly displays cutaneous RM. Patients with IWC are born with
erythematous scaly skin, and during childhood they start to develop confetti-like patches of histologically normal
appearing skin, in which the mutation has been lost. These patches increase in size and number over time,
eventually becoming thousands, each of which is an independent event of reversion of the disease-causing
mutation. Moreover, the expansion of these clones suggests the existence of opposing selective pressures on
the revertant clones and mutant cells, which is suggestive of cellular competition. Our lab recently discovered
that IWC is caused by dominant negative mutations in the tail domains of the keratin 1 (KRT1) or 10 (KRT10)
intermediate filament genes which normally contribute to the stability of the cytoskeleton and reside in the
cytoplasm. These mutations result in nuclear mislocalization of affected keratins, which lead to an increase in
DNA damage and result in copy-neutral loss of heterozygosity. The molecular mechanisms regulating
reversion and the steps leading to recombination are largely unknown, and competition between mutant
and revertant cells is not well understood. In order to achieve visualization of WT or K10 IWC keratinocytes
and their nuclei, I crossed K10IWC/K14-CreERT/mTmG with K14-CreERT/H2BmCherry mouse (mCherry nucleus)
to create K10 WT (mTomato) or K10 IWC (mGFP) keratinocytes with readily observable mCherry nuclei. To
interrogate the mechanism underlying intercellular competition, I will use this novel triple-fluorescence IWC
mouse to perform IVLI of mosaic K10IWC epidermis in vivo and to perform immunofluorescence assays in vitro
to determine the cellular behaviors that result in clonal advantage of wild type over mutant keratinocytes. I will
also perform single cell RNA sequencing of mutant and wild type keratinocytes from K10IWC mice to identify
specific mediators affecting competition. Second, to explore the mechanisms of reversion, we have also
developed an in vitro system to quantify the rate of reversion employing heterozygous Tk1 knockout (Tk1+/-)
murine keratinocytes. In this system, cells expressing at least a functional copy of the tk enzyme, which turns
trifluorothymidine (TFT) into a toxic metabolite, die when grown in TFT-medium. Cells only form colonies, if
recombination at the tk locus occurs resulting in the loss of the tk enzyme. I have found that higher rates of
colony formation result from expression of IWC mutant KRT10 and KRT but the steps leading to reversion are
still unclear. To do this, I will perform a CRISPR knockdown screen paired with our in vitro Tk1+/- system, which
will allow for a high-throughput, unbiased assessment o...

## Key facts

- **NIH application ID:** 10315913
- **Project number:** 1F31AR079928-01
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** DIANA ALEXANDRA YANEZ
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $30,891
- **Award type:** 1
- **Project period:** 2021-08-16 → 2023-08-15

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10315913

## Citation

> US National Institutes of Health, RePORTER application 10315913, Deciphering the Mechanism of Revertant Mosaicism and Cellular Competition in Ichthyosis with Confetti (1F31AR079928-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10315913. Licensed CC0.

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