# Elucidating an Xist-dependent program of sexually dimorphic alternative splicing in the mammalian brain

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $641,663

## Abstract

PROJECT SUMMARY
Women and men are well known to have different propensities to neuropsychiatric illness, but the source of
these differences is not understood. In particular, the molecular events that determine functional dimorphism
between the female and male brain need to be defined. We will examine how the female-specific long
noncoding RNA Xist and its newly identified interaction with the pre-mRNA splicing regulators PTBP1 and 2
affect gene expression and alternative splicing in the female brain. The project will use expertise and tools
developed in three labs for the study of Xist RNA, of neuronal splicing regulation by the PTB proteins, and of
gene expression and alternative splicing using computational methods. RNA-seq data from defined regions of
both human and mouse brain will be analyzed using the new rMATS analysis tool to create a large statistically
robust database of differential gene expression and alternative pre-mRNA splicing between males and
females. Expression and splicing changes will be correlated with changes in PTBP1/2 mRNA and Xist across
the same datasets to define genes potentially regulated by these molecules at the transcriptional and post-
transcriptional levels. Female specific patterns of expression and splicing caused by the XX genotype will be
distinguished from events driven by female hormones using four core genotype mice. Xist targeting will be
confirmed using conditional Xist alleles that allow either removal or activation of Xist during brain development
and measurement of the resulting changes in splicing. The expression of Xist relative to PTBP2 will be
quantified over neuronal differentiation in culture. The PTBP targeting of Xist-dependent changes in splicing
will be confirmed in PTBP2 knockout and PTBP1 transgenic mice, and by transcriptome-wide binding analyses
by iCLIP. Alternative splicing is a widespread mechanism of gene regulation, but has been only minimally
examined in relation to the XX genotype of female cells. Using sophisticated new genome-wide methods and
molecular tools, these studies promise to identify new genetic determinants of sexual dimorphism in the
mammalian brain and to elucidate their underlying molecular mechanisms. In the longer term, the identified
molecular changes driven by Xist and PTBP will provide entrée to the examination of the functional
consequences of these dimorphisms.

## Key facts

- **NIH application ID:** 9922380
- **Project number:** 5R01MH109166-05
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Douglas L Black
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $641,663
- **Award type:** 5
- **Project period:** 2016-07-01 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9922380

## Citation

> US National Institutes of Health, RePORTER application 9922380, Elucidating an Xist-dependent program of sexually dimorphic alternative splicing in the mammalian brain (5R01MH109166-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9922380. Licensed CC0.

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