# X-chromosome Inactivation Catalyzed by Genes That Escape X-inactivation

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2020 · $411,848

## Abstract

Abstract
Epigenetic transcriptional regulation is required for a myriad of developmental processes as well as being a
significant contributor to human diseases. X-chromosome inactivation provides an experimentally tractable
system for the dissection of epigenetic inheritance. X-inactivation results in the mitotically-heritable
transcriptional inactivation of one X-chromosome in female mammals, thereby equalizing X-linked gene
dosage between males and females. X-inactivation requires the Xist long non-coding RNA that is expressed
only from the inactive X-chromosome. Current models posit that Xist RNA induction and coating of the X-
chromosome in cis triggers a series of epigenetic events that culminates in X-inactivation. Notably, how Xist is
selectively induced in females and not at all in males and how it triggers silencing are still unresolved
questions. The objective of this proposal is to address how Xist expression and X-linked gene silencing are
triggered during X-inactivation. Our central hypothesis, based on our published work and preliminary data, is
that genes that escape X-inactivation function as dose-sensitive factors that induce Xist and, separately,
potentiate X-linked gene silencing selectively in females. X-inactivation escapees are expressed from both X-
chromosomes in XX females, including from the otherwise inactivated X-chromosome; hence, their expression
is higher in females compared to XY males. We developed and employed a custom allele-specific RNA-
sequencing pipeline to compile a list of the escape genes in mouse epiblast stem cells, which harbor an
inactive-X. We then prioritized validated escapees that are predicted to be evolutionarily conserved and which
function as transcriptional/chromatin regulators for a role in inducing X-inactivation. In this proposal, we
systematically test the dose-dependent and biochemical activities of two of these escape genes in triggering
Xist expression and X-linked gene silencing using unbiased and integrated high-throughput approaches. The
results are expected to inform how genes along the length of the X-chromosome are silenced and why females
undergo X-inactivation and males do not. The epigenetic factors and mechanisms that execute X-inactivation
are known to overlap with those that regulate embryonic development and disease progression. Thus,
understanding the cascade of epigenetic events that characterizes X-inactivation offers a window into
identifying the common factors and mechanisms that establish epigenetic expression patterns broadly.

## Key facts

- **NIH application ID:** 9978593
- **Project number:** 5R01GM124571-04
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** SUNDEEP KALANTRY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $411,848
- **Award type:** 5
- **Project period:** 2017-09-08 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9978593

## Citation

> US National Institutes of Health, RePORTER application 9978593, X-chromosome Inactivation Catalyzed by Genes That Escape X-inactivation (5R01GM124571-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9978593. Licensed CC0.

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