SoxGenes Show Spatiotemporal Expression during Murine Tongue and Eyelid Development

Abstract

The tongue is a critical organ, involved in functions such as speaking, swallowing, mastication, and degustation. Although Sox genes are known to play critical roles in many biological processes, including organogenesis, the expression of the Sox family members during tongue development remains unclear. We therefore performed a comparative in situ hybridization analysis of 17 Sox genes (Sox1–14, 17, 18, and 21) during murine tongue development. Sox2, 4, 6, 8, 9, 10, 11, 12, and 21 were found to be expressed in the tongue epithelium, whereas Sox2, 4–6, 8–11, 13, and 21 showed expression in the mesenchyme of the developing tongue. Expression of Sox1, 4, 6, 8–12, and 21 were observed in the developing tongue muscle. Sox5 and 13 showed expression only at E12, while Sox1 expression was observed only on E18. Sox6, 8, 9, and 12 showed expression at several stages. Although the expression of Sox2, 4, 10, 11, and 21 was detected during all the four stages of tongue development, their expression patterns differed among the stages. We thus identified a dynamic spatiotemporal expression pattern of the Sox genes during murine tongue development. To understand whether Sox genes are involved in the development of other craniofacial organs through similar roles to those in tongue development, we also examined the expression of Sox genes in eyelid primordia, which also contain epithelium, mesenchyme, and muscle. However, expression patterns and timing of Sox genes differed between tongue and eyelid development. Sox genes are thus related to organogenesis through different functions in each craniofacial organ.

Sorting Sox: Diverse Roles for Sox Transcription Factors During Neural Crest and Craniofacial Development

“…The observed skeletal defects such as micrognathia, broad/full nasal tip, and prominent chin are consistent with SOX5 having a role in chondrogenesis. Sox5 is strongly expressed in Meckel's cartilage in mice (Ishikawa et al, 2018), which could explain the presentation of micrognathia, specifically. The general lack of severity of these craniofacial phenotypes is most likely due to individuals possessing other functional SOXD alleles, which is supported by Sox5 −/− having only minor skeletal defects (Smits et al, 2001).…”

“…n/a n/a n/a n/a More detailed expression patterns for factors can be found in: (Kawasaki et al, 2015;Watanabe et al, 2016;Ishikawa et al, 2018). Epithelial (Epi), Mesenchymal (Mes), Muscle (Mus), Not expressed (n.e).…”

“…The autosomal dominant mode of inheritance is typically associated with nonsense mutations in the SOX18 transactivation domain while the autosomal recessive form is marked by missense mutations within the HMG domain (Valenzuela et al, 2018). Expression data in mice indicates that Sox18 primarily localizes to sites of vascularization within the developing murine craniofacial complex (Ishikawa et al, 2018). Given this expression, it is unclear how loss of Sox18 could result in phenotypes such as microcephaly or broad nasal tip.…”

Morphogenesis of fungiform papillae in developing miniature pigs

“…A recent study indicated that a reduction in Sox2 expression to 20 % of normal levels causes papilla placodes and early papillae to begin developing but fail to reach maturity, while filiform papillae develop normally [ 46 ]. In contrast, overexpression of Sox2 induces the development of atypical fungiform-like papillae, but filiform papillae do not develop [ 47 ]. This finding suggested that Sox2 regulates the differentiation of endodermal progenitor cells in the mouse tongue into taste bud cells rather than keratinocytes [ 46 ].…”

“…This finding is different from the expression of SOX2 in the fungiform papilla of mice. Moreover, Sox2 is expressed in the mesenchyme between the superior and inferior longitudinal and genioglossus muscles in the middle and posterior regions of the tongue as well as in the epithelium throughout the tongue [ 47 ]. Therefore, at which stage SOX2 plays a role in the development of tongue fungiform papillae in small pigs is unclear, and its developmental network still needs to be further constructed and explored.…”