Cloning and expression analysis of <i>Sall4</i>, the murine homologue of the gene mutated in Okihiro syndrome

Abstract

SALL4 is one out of four human homologues of the Drosophila region-specific homeotic gene spalt(sal). Heterozygous mutations of SALL4 on chromosome 20q13.13→ q13.2 cause the autosomal dominant Okihiro syndrome which is characterized by radial limb defects, Duane anomaly and hearing loss. We have partially cloned the murine homologue of this gene, named Sall4, and completed the coding sequence by comparison to available EST and genomic sequences in the GenBank database. This comparison also revealed the chromosomal location of Sall4 on mouse chromosome 2H3 and suggested that a predicted testis expressed gene Tex20 at the very same locus is most likely not a gene on its own but part of the Sall4 3′ UTR. We analyzed the expression of Sall4 during early embryogenesis by whole mount in situ hybridization and in the adult mouse by Northern blotting. In adult tissues, Sall4 expression is only found in testis and ovary. During embryonic development, Sall4 expression is widespread in early embryos and becomes gradually confined to the head region and the primitive streak. Prominent expression in the developing midbrain, branchial arches and the limbs suggests an important function of Sall4 during development of these structures as expected from the observation in Okihiro syndrome patients.

A Sall4 mutant mouse model useful for studying the role of Sall4 in early embryonic development and organogenesis

“…A reduction of mRNA transcript was evident in Sall4 m1/+ embryos compared with Sall4 +/+ embryos. Whole mount analysis of Sall4 m1/+ embryos at E10.5 revealed that Sall4 mRNA was expressed with the expected tissue distribution, namely midbrain, branchial arch, and limb bud mesenchyme (Kohlhase et al, 2002a;Sakaki-Yumoto et al, 2006), however, the levels of Sall4 mRNA were very low compared with wild type embryos ( Fig. 1e,f).…”

“…Murine Sall4 (Kohlhase et al, 2002a) is required for inner cell mass proliferation in early embryonic development (Sakaki-Yumoto et al, 2006). It also interacts with other transcription factors, such as Sall1 and the Tbx family of transcription factors to control the development of the anorectal region, kidney, heart, limbs and brain, by acting on downstream targets including Fgf10 (Kiefer et al, 2003;Koshiba-Takeuchi et al, 2006;Sakaki-Yumoto et al, 2006).…”

Temporal ChIP-on-chip reveals Biniou as a universal regulator of the visceral muscle transcriptional network

“…In mice, their orthologs, Ptk7 and Sall4, are expressed in newly formed mesoderm within the primitive streak area at the posterior end of the embryo (Fig. 6A,B; Kohlhase et al 2002;Jung et al 2004). Importantly, both genes have consistently lower levels of expression in Foxf1 homozygous mutant embryos compared with wild-type littermates at E8.5, in all mutant embryos examined (Fig.…”

Identification of the nuclear localization signal of SALL4B, a stem cell transcription factor

“…[1][2][3] SALL4 expression is high in stem cells and downregulated during development, and its expression is largely absent in most adult tissues. [4][5][6] As a stem cell transcription factor, SALL4 is capable of increasing reprogramming efficiency of somatic cells to become induced pluripotent stem cells.…”