1: Dev Biol. 2005 Mar 15;279(2):481-90. 

Sox9 and Nkx2.5 determine the pyloric sphincter epithelium under the control of
BMP signaling.

Theodosiou NA, Tabin CJ.

Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston,
MA 02115, USA.

The organs of the digestive tract are specified by coordinated signaling between
the endoderm and mesoderm during development. These epithelial-mesenchymal
interactions lead to the organ-specific morphogenesis and differentiation of
regions along the gut tube. In this paper, we show that in the chick, the
SRY-related transcription factor Sox9 is a marker for the posterior gizzard.
Viral misexpression of Sox9 in the gizzard mesoderm is sufficient to specify
epithelium characteristic of the pyloric sphincter. Sox9 expression is normally
limited to the region of the posterior gizzard under the regulation of BMP
signaling from the adjacent midgut. Misexpression of an activated form of BMPR1b
in the gizzard upregulates Sox9 expression, while the BMP antagonist noggin
down-regulates Sox9 expression in the gizzard mesoderm. Previously, Nkx2.5 was
identified as a marker for the mesoderm of the pyloric sphincter. As with Sox9,
BMP signaling appears to regulate Nkx2.5 and its ability to determine the
pyloric epithelium. Despite these similarities, our evidence suggests that Sox9
and Nkx2.5 are regulated independently by BMP signaling, and act coordinately to
specify the pyloric sphincter.

PMID: 15733673 [PubMed - indexed for MEDLINE]


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