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Gene Expr Patterns
2010 Jan 01;107-8:338-44. doi: 10.1016/j.gep.2010.07.005.
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Expression of components of Wnt and Hedgehog pathways in different tissue layers during lung development in Xenopus laevis.
Yin A
,
Winata CL
,
Korzh S
,
Korzh V
,
Gong Z
.
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Although Wnt and Hedgehog (Hh) signaling pathways play important roles in mouse lung development, these have not been explored in the development of Xenopus lung. This may be due to the lack of specific molecular markers for different layers of tissue in Xenopus lung and/or insufficient knowledge on expression patterns of Wnt and Hh signaling components in Xenopus lung. In this study, we first described the early morphogenesis of Xenopus laevis lung by using surfactant protein C (sftpc) as a marker of lungepithelium and compared it with the expression patterns of several genes of Wnt and Hh pathways in Xenopus lungs. Our data showed that wnt7b was expressed in the entire lungepithelium from stage 37 to stage 45, while two other Wnt signaling components, wnt5a and wif1 (wnt inhibitory factor 1), were expressed in the mesenchyme layer of the entire lungs through stages 39-41. We also found that sonic hedgehog (shh) was expressed at stage 41 only in the anterior, but not in the posterior part of the lungs. These results show the expression of wnt5a, wnt7b, wif1 and shh in different layers of tissue of Xenopus lungs at early developmental stages, which implies different roles of these genes in the early development of Xenopus lungs. Our study for the first time defined specific molecular markers for description of early lung development in Xenopus, as well as provided information about expression of components of Wnt and Hh pathways in early Xenopus lungs, which should be useful for future functional studies.
Fig. 1. Expression of sftpc in early lung development of X. laevis. (A) Undetectable sftpc expression at stage 35/36. (B) Earliest expression of sftpc at stage 37/38. (C) sftpc expression is specifically restricted to the lung bud at stage 39. (D, E and F) Cross section of a stage 39 embryo shows sftpc expression in lung buds. Note that the whole lung is located ventral to the esophagus (es). (G) Ventro–lateral view of sftpc expression in lungs at stage 41. (H) Epithelial expression of sftpc in the anterior part of lungs at a point just before the separation of the two lung tubes. (I) Epithelial expression of sftpc in the two separated posteriorlung tubes. (I′) The image of the boxed region in (I) shows sftpc staining in the epithelium. Note that at this stage, with the elongation of lungs, the posterior parts of the lung tube extended to the dorsal side of the esophagus. (J) Ventro–lateral view of sftpc expression in lungs at stage 45. sftpc is expressed in the lungs anteriorepithelium (K) and posteriorepithelium (L). (L′) The image of the boxed region in (L) shows sftpc staining in the epithelium layer. Note at stage 45, the posterior part of lungs is located dorsal to the midgut. Red arrows and dotted red circles indicate lungs. Abbreviations: es, esophagus; mg, midgut; nc, notochord.
Fig. 2. Expression of wnt7b in Xenopus lungepithelium. (A) wnt7b is not expressed in the lung bud at stage 35/36. (B) The earliest wnt7b expression in the lung bud is detected at stage 37/38. (C) Expression of wnt7b in the lung bud at stage 39. (D, E and F) Transverse sections of stage 39 embryos show wnt7b expression in the entire lungepithelium. (G) wnt7b is expressed in lungs at stage 41. (H, I and J) Transverse sections of the embryo in (G) show that wnt7b is expressed in the entire lungepithelium with stronger expression in the lateral part of lung tubes (I). (K) wnt7b is expressed along the entire lung tube at stage 45. (L, M) Transverse sections show wnt7b expression in the lungepithelium at stage 45. (M′) The magnified image of the boxed region in (M). Red arrows indicate lungs. Abbreviations: es, esophagus; nc, notochord.
Fig. 3. Expression of wnt5a and wif1 in the mesenchyme of Xenopus lung. (A) WISH image shows wnt5a expression in the lung bud at stage 39. (B) Transverse section of a stage 39 embryo depicts wnt5a expression in the lungmesenchyme. (B′) DAPI stained section for the boxed region in (B) to better depict lung structure (outlined). (C) Stage 41 WISH shows wnt5a expression in the lungs. (D and E) Expression of wnt5a in the lungmesenchyme revealed by transverse section shows high expression in the laterallung tubes. (E′) The magnified image of the boxed region in (E) indicates that wnt5b expression is restricted to the mesenchyme. (F) wif1 is expressed in the lung bud at stage 39. (G) Transverse section confirms presence of wif1 expression in the lungmesenchyme. (G′) DAPI stained section in the boxed region in (G) to better depict lung structure (outlined). (H) wif1 expression in a stage 41 embryolung is shown in a dorsal view. (I and J) Transverse section of a stage 41 embryo illustrates wif1 expression in the anterior and posteriorlungmesenchyme. (J′) Merged bright field and DAPI image of the boxed region in (J) shows wif1 expression in the mesenchyme. Red arrows indicate lungs. Abbreviations: es, esophagus; nc, notochord; ep: epithelium; mc: mesenchyme.
Fig. 4. Expression of shh and ihh in early Xenopus lung development. (A–E) WISH detection of expression of shh. (A) WISH shows absence of shh expression in the lung bud at stage 39. (B) shh expression at anterior part of lungs at stage 41. Transverse section shows the expression of shh in the anterior (C) and middle (D) part of lungepithelium, but not in posterior (E) epithelium of the lung bud at stage 41. (F–I) WISH detection of expression of ihh. No expression of ihh was detected in the lung bud at stage 39 (F) and stage 41 (G). (H and I) Transverse section indicates lack of ihh expressed in the anterior or posterior part of lungs at stage 41. Red arrows and dotted red circles indicate lungs. Abbreviations: es, esophagus; nc, notochord.
