Institute of Human Genetics, University of Göttingen, Göttingen, Germany.
PLoS One. 2011;6(10):e25908. doi: 10.1371/journal.pone.0025908. Epub 2011 Oct 4.
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 3'untranslated 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 5' 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 Vsig1(-/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 Vsig1(-/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.
VSIG1 是免疫球蛋白超家族的一种细胞粘附蛋白，在胃、睾丸以及某些胃癌、食管癌和卵巢癌中优先表达。在这里，我们描述了在胃的产前和产后发育过程中，小鼠 VSIG1 的三种选择性剪接异构体的表达模式，以及 VSIG1 在胃上皮分化中的潜在功能。我们表明，在胃发育的早期阶段表达在 3'非翻译区中存在差异的异构体 Vsig1A 和 Vsig1B。免疫组织化学分析显示，VSIG1 局限于腺上皮的黏着连接。较短的转录本 Vsig1C 局限于睾丸，编码一个 N 端截断的蛋白质，推测受位于外显子 1b 上游的内部启动子调控。为了确定外显子 1a 的 5'侧翼区是否特异性地将 Vsig1 的表达靶向胃上皮，我们生成并分析了转基因小鼠。位于外显子 1a 上游的 4.8kb 片段足以将报告基因的表达靶向转基因胃的腺上皮。为了确定 VSIG1 在胃上皮发育过程中的作用，我们在外胚层干细胞（ESCs）中使 X 连锁的 Vsig1 失活。尽管 Vsig1(-/Y) ESCs 仅能够生成低毛色嵌合体小鼠，但没有雄性嵌合体将靶向等位基因传递给它们的后代，这表明 Vsig1(-/Y) 细胞的高贡献导致嵌合胚胎的致死性。嵌合胃的分析显示，VSIG1 缺失细胞在腺区内部分化为鳞状上皮。这些结果表明，VSIG1 是建立胃中腺上皮与鳞状上皮的必要条件。
