# Function of SF3B4 in neural crest development

> **NIH NIH F32** · NEW YORK UNIVERSITY · 2022 · $70,602

## Abstract

Nager syndrome (OMIM#154400) is a rare craniofacial and limb disorder characterized by midface retrusion,
micrognathia, absent thumbs, and radial hypoplasia. This disorder results from mutations in the SF3B4 (splicing
factor 3b, subunit 4) gene, which encodes SAP49, a protein that is a component of the spliceosome. The
spliceosome is a complex of RNA and proteins that function together to remove introns and join exons from
transcribed pre-mRNA. While the spliceosome is present and functions in all cells of the body, many
spliceosomopathies – including Nager syndrome – are often cell- or tissue-specific in their pathology. In Nager
syndrome patients it is the neural crest (NC)-derived craniofacial skeletal structures that are affected. The
mechanisms underlying Nager syndrome pathology, as well as its tissue-specificity are poorly understood. In
this application, we will use a recently generated Xenopus tropicalis Sf3b4 mutant line and embryonic stem cell
(ESC)-derived neural crest cells (NCCs) to tease apart these mechanisms by identifying the targets and binding
partners of SF3B4. This combination of in vivo and in vitro approaches will provide novel insights into the
mechanisms driving craniofacial defects in the context of Nager syndrome. The proposed experiments will test
the hypothesis that SF3B4 has NC-specific targets and/or binding partners, and upon mutation these interactions
are disrupted or lost, leading to Nager syndrome-associated craniofacial defects. We have crafted three specific
aims to test this possibility. Specific Aim 1: In collaboration with the National Xenopus Resource (NXR; Woods
Hole, MA) we have generated an Sf3b4 Xenopus tropicalis mutant line using the CRISPR/Cas9 technology, and
we propose to perform the phenotypic characterization these animals by evaluating at different time points NC
progenitor formation, proliferation, migration, and subsequent craniofacial cartilage development. Aim 2: We
hypothesize that SF3B4 is required for NC progenitor formation by regulating the pre-mRNA processing of key
regulators of NC fate. To identify these regulators, we will analyze the global impact of SF3B4 knockdown on
pre-mRNA processing by comparing transcripts from wild-type and Sf3b4 mutant Xenopus tropicalis embryos
using RNA-seq and focusing on transcripts showing intron retention. Aim 3: As an alternative to the pre-mRNA
processing of NC-specific regulators, we hypothesize that the tissue-specific function of SF3B4 may depend on
interactions with partner molecules preferentially enriched in the NC lineage. To this end, we will express a
FLAG-tagged human SF3B4 construct in ESC-derived NCCs to identify by immunoprecipitation and mass
spectrometry SF3B4 NC-specific interactors as the possible culprit for the cell-type specific activity of SF3B4 in
Nager syndrome. Altogether these studies will provide novel insights into the mechanisms underlying Nager
syndrome craniofacial defects, through the characterization of a new muta...

## Key facts

- **NIH application ID:** 10450642
- **Project number:** 5F32DE030699-02
- **Recipient organization:** NEW YORK UNIVERSITY
- **Principal Investigator:** Casey Griffin
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $70,602
- **Award type:** 5
- **Project period:** 2021-09-01 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10450642

## Citation

> US National Institutes of Health, RePORTER application 10450642, Function of SF3B4 in neural crest development (5F32DE030699-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10450642. Licensed CC0.

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