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Mech Dev
2002 Dec 01;119 Suppl 1:S27-30. doi: 10.1016/s0925-4773(03)00087-x.
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Gene expression pattern analysis of the tight junction protein, Claudin, in the early morphogenesis of Xenopus embryos.
Fujita M
,
Itoh M
,
Shibata M
,
Taira S
,
Taira M
.
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To study how epithelial layers are formed during early development in Xenopus embryos, we have focused on Claudin, the major component of the tight junction. So far, 19 claudin genes have been found in the mouse, expressed in different epithelial tissues. However, though a number of cytological studies have been done for the roles of Claudins, their expression patterns and functions during early embryogenesis are largely unknown. We found three novel Xenopus claudin genes, which are referred to as claudin-4L1, -4L2, and -7L1. At the early gastrula stage, claudin-4L1, -4L2, and -7L1 mRNAs were detected in the ectoderm and in the mesoderm. At the late gastrula stage, claudin mRNAs were detected in the ectoderm through the involuting archenteron roof. At the neurula stage, claudin-4L1/4L2 and -7L1 mRNAs were differentially expressed in the neural groove and the epidermal ectoderm. At the tailbud stage, the claudin mRNAs were found in the branchial arches, the otic vesicles, the sensorial layer of the epidermis, and along the dorsal midline of the neural tube. In addition, claudin-4L1/4L2 mRNAs were detected in the pronephros and the endoderm, whereas claudin-7L1 mRNA was observed in the epithelial layer of the epidermis.
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14516656
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Fig. 2. Expression of Xenopus claudin-4L1, -4L2, and -7L1 genes in gastrula embryos. (a–c) Vegetal view of midgastrulae. (d,e) An animal pole area of sagittal section of early gastrula (-4L1) in bright field (d) and DAPI staining (e). The blastocoel was collapsed in this section. Sagittal hemisections of early gastrulae (f–h) or late gastrulae (i–k). (l–n) Enlargement of upper part of the archenteron of i–k, respectively. ac, archenteron; bc, blastocoel; el, epithelial layer of ectoderm; sl, sensorial layer of ectoderm; arrowhead, blastopore; small arrows in f–h, mesodermal expression; large arrows in l–n, expression in the archenteron roof; dotted line in i–k indicates the blastocoel. Developmental stages (st.) are shown above each column of pictures.
Fig. 3. Expression of Xenopus claudin-4L1, -4L2, and -7L1 genes in neurula to early tailbud stage embryos. (a–c) early neurula. (d–i) midneurula. (j–o) late neurula. (p–r) tailbud stage embryo. (a–l) dorsal view. Anterior is up. (m–r) lateral view. Anterior to the left. br, Branchial arch; ng, neural groove; op, otic placode; ov, otic vesicle; pn, pronephros.
Fig. 4. Expression of Xenopus claudin genes examined by transverse sections of embryos. Expression of either Claudin-4L1 or -4L2 was shown, because Claudin-4L1 and -4L2 showed similar expression patterns. (a) claudin-4L1 at stage 15. (b) claudin-4L2 at stage 17/18. (c) claudin-4L2 at stage 21. (e–g) claudin-7L1 at stage 15 (e), stage 17/18 (f), and stage 21 (g). (d,h) Enlargement of the ventral region of c and g, respectively. Dorsal is up. Upper panels, bright field; lower panels, DAPI staining. el, epithelial layer of epidermal ectoderm; end, endoderm; sl, sensorial layer of epidermal ectoderm.
