Characterizing the Expression Pattern and Requirement of Sf3b4 During Mouse Embryonic Development

Abstract

Nager Syndrome (NS) is a rare disorder that affects the face as well as the limb including both hands and feet. Patients with NS typically have malar and mandibular hypoplasia, cleft palate, as well as hearing problems. Limb defects include radial hypoplasia as well as thumb abnormalities. Using exome sequencing, NS was attributed to haploinsufficiency of the SF3B4 gene, an important component of the U2 subunit of the spliceosome complex. We hypothesized that Sf3b4 will show tissue‐specific expression during development and that mice with heterozygous mutation in this gene will model NS. To create heterozygous Sf3b4 mutant mice, we used CRISPR/Cas9 to target loxP sequences in intronic regions flanking exon 2 and 3 of the Sf3b4 gene. We will breed loxP founders with Wnt‐1 Cre transgenic mice, and report the resulting phenotypes. Additionally, whole mount in situ hybridization was used to examine expression of Sf3b4 during embryonic development of wild type mouse. We found that Sf3b4 shows ubiquitous expression at early stages of development. In midgestation embryos, although still globally expressed, Sf3b4 expression becomes stronger in the maxillomandibular region, limbs and tail bud. Our research will elucidate the expression of Sf3b4 in embryonic tissues affected in NS patients and generate a mouse model that will be used to further characterize the molecular basis of this syndrome. As there are currently no mouse models or therapy available for NS our work will help to identify some of the targets of Sf3b4 and pave the path for the creation of new therapies for spliceosomal disorders.Support or Funding InformationCanadian Institutes of Health ResearchThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Human stem cell model of neural crest cell differentiation reveals a requirement of SF3B4 in survival, maintenance, and differentiation

“…Previous studies in mouse, fish, and frog have strived to model Nager/Rodriguez syndrome in order to tease apart the underlying mechanism of the pathology. In mouse, it has been shown that homozygous Sf3b4 mutants are embryonic lethal (Yamada et al, 2020), while heterozygous Sf3b4 mutants have microcephaly and homeo?c posterioriza?on of the vertebrae (Yamada et al, 2020;Kumar et al, 2023). The axial skeleton defects have been adributed to mis-splicing of chroma?n remodelers and dysregula?on of Hox gene expression (Kumar et al, 2023).…”

“…In mouse, it has been shown that homozygous Sf3b4 mutants are embryonic lethal (Yamada et al, 2020), while heterozygous Sf3b4 mutants have microcephaly and homeo?c posterioriza?on of the vertebrae (Yamada et al, 2020;Kumar et al, 2023). The axial skeleton defects have been adributed to mis-splicing of chroma?n remodelers and dysregula?on of Hox gene expression (Kumar et al, 2023). In zebrafish, sf3b4 muta?on causes massive cell death in the re?na of the eye (Ulhaq et al, 2023), reminiscent of another spliceosomopathy, re?ni?s pigmentosa (Griffin and Saint-Jeannet, 2020).…”