Adhesion Protein VSIG1 Is Required for the Proper Differentiation of Glandular Gastric Epithelia
et al. (2011) Adhesion Protein VSIG1 Is Required for the Proper Differentiation of Glandular
Gastric Epithelia. PLoS ONE 6(10): e25908. doi:10.1371/journal.pone.0025908
Adhesion Protein VSIG1 Is Required for the Proper Differentiation of Glandular Gastric Epithelia
Odgerel Oidovsambuu 0
Gunsmaa Nyamsuren 0
Shuai Liu 0
Wolfgang Go ring 0
Wolfgang Engel 0
Ibrahim M. Adham 0
Olivier Gires, Ludwig-Maximilians University, Germany
0 Institute of Human Genetics, University of Go ttingen , Go ttingen , Germany
VSIG1, a cell adhesion protein of the immunoglobulin superfamily, is preferentially expressed in stomach, testis, and certain gastric, esophageal and ovarian cancers. Here, we describe the expression patterns of three alternatively spliced isoforms of mouse Vsig1 during pre- and postnatal development of stomach and potential function of Vsig1 in differentiation of gastric epithelia. We show that isoforms Vsig1A and Vsig1B, which differ in the 39untranslated region, are expressed in the early stages of stomach development. Immunohistochemical analysis revealed that VSIG1 is restricted to the adherens junction of the glandular epithelium. The shorter transcript Vsig1C is restricted to the testis, encodes an N-terminal truncated protein and is presumably regulated by an internal promoter, which is located upstream of exon 1b. To determine whether the 59 flanking region of exon 1a specifically targets the expression of Vsig1 to stomach epithelia, we generated and analyzed transgenic mice. The 4.8-kb fragment located upstream of exon 1a was sufficient to direct the expression of the reporter gene to the glandular epithelia of transgenic stomach. To determine the role of VSIG1 during the development of stomach epithelia, an X-linked Vsig1 was inactivated in embryonic stem cells (ESCs). Although Vsig12/Y ESCs were only able to generate low coat color chimeric mice, no male chimeras transmitted the targeted allele to their progeny suggesting that the high contribution of Vsig12/Y cells leads to the lethality of chimeric embryos. Analysis of chimeric stomachs revealed the differentiation of VSIG1-null cells into squamous epithelia inside the glandular region. These results suggest that VSIG1 is required for the establishment of glandular versus squamous epithelia in the stomach.
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The gastrointestinal tract is developed from the primitive gut
tube, which comprises the endodermal epithelium and
surrounding mesoderm. During embryonic development, endoderm of the
foregut gives rise to the epithelia of the esophagus, stomach and
duodenum, while that of the mid- and hindgut differentiate into
the epithelial layer of the intestine, caecum and colon [1,2]. In
mice, the pseudostratified epithelia of the foregut
transdifferentiates at embryonic day E13.5 into stratified squamous epithelia in
the esophagus and forestomach, and into columnar glandular
epithelia in the distal stomach [3]. The squamous epithelium of
murine embryos is not keratinized and composed of multilayered
epithelia, becoming keratinized at approximately 4 weeks after
birth [4]. The terminal differentiation of glandular epithelia begins
on E14.5 and continues into early postnatal development, where
the monolayered epithelium invaginates into the neighboring
mesoderm and forms a primitive gastric unites [3]. Subsequent
cytodifferentiation leads to the development of different cell
lineages in the gastric glands [5].
The primary structure of cell adhesion molecules that belong to
the immunoglobulin superfamily (IgSF) is characterized by the
presence of one or more Ig-like domains in the extracellular region
that is implicated in cell-cell adhesion, a transmembrane domain,
and one cytoplasmic C-terminal region. The cytoplasmic tail of
adhesion molecules is linked to the actin cytoskeleton through
many peripheral membrane proteins, including members of the
catenin, partitioning-defective (PAR) and zonula occludens (ZO)
families, which strengthen cell-cell adhesion and establish
epithelial cell polarization [6]. VSIG1/A34, a novel member of
IgSF, was first identified and characterized in humans. VSIG1, an
X-linked gene, is predominantly expressed in stomach and testis,
and is characterized by the presence of two Ig-like domains [7].
VSIG1 is related in polypeptide sequence to CTX proteins.
Members of the CTX family are localized to adherens junctions
between epithelial and endothelial cells of different tissues. Some
CTX-like proteins are expressed in the testis, namely CAR,
BTIgSF and JAM C, while A33 is exclusively expressed in the
epithelial cells of the gastrointestinal tract [812].
In the present study, we determined the expression patterns of
multiple spliced transcripts of murine Vsig1 during both prenatal
and postnatal development of the stomach. To determine the 59
region that specifically targets the expression of mouse Vsig1 to the
stomach, we generated and analyzed transgenic mice expressing
enhanced green fluorescent protein (EGFP) under co (...truncated)