The Ontogeny of poll, fbxw4, sufu mRNA expression during Development of the Chick Limb

Abstract

Split‐hand/split‐foot malformation (SHFM), also known as ectrodactyly, is a congenital limb malformation that is characterized by absence or reduction of the central digital rays of the hands and feet. To date there are five well established loci for SHFM. At one of these loci, SHFM3 at chromosome 10q24, tandem duplications have been associated with the SHFM phenotype in humans. The smallest reported duplication includes the genes POLL, BTRC, DPCD, and a portion of FBXW4. Another gene near the duplicated region, SUFU, has been shown to be overexpressed in SHFM3 patients. RNA collected from chicken embryo limb buds (E2‐15) was analyzed for expression of poll, fbxw4, and sufu by reverse‐transcription polymerase chain reaction (RT‐PCR). Preliminary studies demonstrate that fbxw4 and sufu are first detected at E5 and are no longer detected after E13, which is consistent with the normal timing of digit patterning in the chicken. No poll expression was observed in limb bud RNA, which is not surprising, given that there is no previous correlation with limb development. These results suggest that both fbxw4 and sufu are expressed in the limb during the period of digit patterning, and while poll is in the commonly duplicated region, it is not expressed in a similar fashion. Future studies will explore the effects that overexpression of fbxw4 and sufu have on limb development in chicken and investigate the expression of other genes from the duplicated region.