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Formation and differentiation of multiple mesenchymal lineages during lung development is regulated by beta-catenin signaling.

De Langhe SP, Carraro G, Tefft D, Li C, Xu X, Chai Y, Minoo P, Hajihosseini MK, Drouin J, Kaartinen V, Bellusci S - PLoS ONE (2008)

Bottom Line: The amplification but not differentiation of Fgf10-expressing parabronchial smooth muscle progenitor cells is drastically reduced.In the angioblast-endothelial lineage, however, only differentiation into mature endothelial cells is impaired.Taken together these findings reveal a hierarchy of gene activity involving ss-catenin and PITX, as important regulators of mesenchymal cell proliferation and differentiation.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology Program, Department of Surgery, Saban Research Institute of Childrens Hospital Los Angeles, Los Angeles, California, USA.

ABSTRACT

Background: The role of ss-catenin signaling in mesodermal lineage formation and differentiation has been elusive.

Methodology: To define the role of ss-catenin signaling in these processes, we used a Dermo1(Twist2)(Cre/+) line to target a floxed beta-catenin allele, throughout the embryonic mesenchyme. Strikingly, the Dermo1(Cre/+); beta-catenin(f/-) conditional Knock Out embryos largely phenocopy Pitx1(-/-)/Pitx2(-/-) double knockout embryos, suggesting that ss-catenin signaling in the mesenchyme depends mostly on the PITX family of transcription factors. We have dissected this relationship further in the developing lungs and find that mesenchymal deletion of beta-catenin differentially affects two major mesenchymal lineages. The amplification but not differentiation of Fgf10-expressing parabronchial smooth muscle progenitor cells is drastically reduced. In the angioblast-endothelial lineage, however, only differentiation into mature endothelial cells is impaired.

Conclusion: Taken together these findings reveal a hierarchy of gene activity involving ss-catenin and PITX, as important regulators of mesenchymal cell proliferation and differentiation.

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Related in: MedlinePlus

Expression pattern of PITX members in the developing wild type and mutant embryonic E13.5 lungs.(a–h) Immunostaining for PITX family members and α-SMA. (a,b) PITX1 expression in wild type lung is detected throughout the distal epithelium. (b) Expression of PITX1 in the CKO lung is not changed compared to WT. (c) PITX2 expression in wild type lung is detected throughout the epithelium as well as in the mesenchyme at the exception of the mesenchyme directly surrounding the proximal epithelium (arrows). (d) In CKO lungs, PITX2 expression is drastically reduced in the epithelium and mesenchyme. (e) In wild type lungs, PITX3 expression is present in the differentiated PSMCs adjacent to the bronchi. (f) In CKO lungs, PITX3 expression is no longer found as a continuous layer around the bronchi likely reflecting a defect in the formation of the PSMC. (g, h) SMA expression on the same section as (e) and (f).
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pone-0001516-g002: Expression pattern of PITX members in the developing wild type and mutant embryonic E13.5 lungs.(a–h) Immunostaining for PITX family members and α-SMA. (a,b) PITX1 expression in wild type lung is detected throughout the distal epithelium. (b) Expression of PITX1 in the CKO lung is not changed compared to WT. (c) PITX2 expression in wild type lung is detected throughout the epithelium as well as in the mesenchyme at the exception of the mesenchyme directly surrounding the proximal epithelium (arrows). (d) In CKO lungs, PITX2 expression is drastically reduced in the epithelium and mesenchyme. (e) In wild type lungs, PITX3 expression is present in the differentiated PSMCs adjacent to the bronchi. (f) In CKO lungs, PITX3 expression is no longer found as a continuous layer around the bronchi likely reflecting a defect in the formation of the PSMC. (g, h) SMA expression on the same section as (e) and (f).

Mentions: The branching defect in CKO lungs is more severe than just the right isomerization initially described in Pitx2 hypomorph embryos and resembles more the phenotype of lungs from mice with a complete inactivation of Pitx2 [25]. We therefore examined the impact of CKO on PITX2 expression and asked whether its homologues, PITX1 and PITX3, are affected by loss of β-catenin. Immunostaining studies showed that PITX1 is present in both WT and CKO distal lung epithelium (Fig. 2a,b). Three Pitx2 isoforms exist a, b and c the latter of which is involved in Left/right asymmetry and is only expressed on the left side of the lung [22]. PITX2 (using antibodies recognizing all three isoforms) is normally found in distal epithelium and mesenchyme but is absent from PSMC around the bronchi (arrow in Fig. 2c), and as expected, PITX2 levels were found to be drastically reduced in the CKO mesenchyme (Fig. 2d). By contrast, PITX3 is expressed exclusively in the differentiated smooth muscle cells around the bronchi in both WT and CKO lungs (Fig. 2e–h), suggestive of a switch from PITX2 to PITX3 expression upon PSMC differentiation. Although the significance of this switch needs to be elucidated, our findings indicate a major impact on PITX2 expression at the protein level.


Formation and differentiation of multiple mesenchymal lineages during lung development is regulated by beta-catenin signaling.

De Langhe SP, Carraro G, Tefft D, Li C, Xu X, Chai Y, Minoo P, Hajihosseini MK, Drouin J, Kaartinen V, Bellusci S - PLoS ONE (2008)

Expression pattern of PITX members in the developing wild type and mutant embryonic E13.5 lungs.(a–h) Immunostaining for PITX family members and α-SMA. (a,b) PITX1 expression in wild type lung is detected throughout the distal epithelium. (b) Expression of PITX1 in the CKO lung is not changed compared to WT. (c) PITX2 expression in wild type lung is detected throughout the epithelium as well as in the mesenchyme at the exception of the mesenchyme directly surrounding the proximal epithelium (arrows). (d) In CKO lungs, PITX2 expression is drastically reduced in the epithelium and mesenchyme. (e) In wild type lungs, PITX3 expression is present in the differentiated PSMCs adjacent to the bronchi. (f) In CKO lungs, PITX3 expression is no longer found as a continuous layer around the bronchi likely reflecting a defect in the formation of the PSMC. (g, h) SMA expression on the same section as (e) and (f).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2211394&req=5

pone-0001516-g002: Expression pattern of PITX members in the developing wild type and mutant embryonic E13.5 lungs.(a–h) Immunostaining for PITX family members and α-SMA. (a,b) PITX1 expression in wild type lung is detected throughout the distal epithelium. (b) Expression of PITX1 in the CKO lung is not changed compared to WT. (c) PITX2 expression in wild type lung is detected throughout the epithelium as well as in the mesenchyme at the exception of the mesenchyme directly surrounding the proximal epithelium (arrows). (d) In CKO lungs, PITX2 expression is drastically reduced in the epithelium and mesenchyme. (e) In wild type lungs, PITX3 expression is present in the differentiated PSMCs adjacent to the bronchi. (f) In CKO lungs, PITX3 expression is no longer found as a continuous layer around the bronchi likely reflecting a defect in the formation of the PSMC. (g, h) SMA expression on the same section as (e) and (f).
Mentions: The branching defect in CKO lungs is more severe than just the right isomerization initially described in Pitx2 hypomorph embryos and resembles more the phenotype of lungs from mice with a complete inactivation of Pitx2 [25]. We therefore examined the impact of CKO on PITX2 expression and asked whether its homologues, PITX1 and PITX3, are affected by loss of β-catenin. Immunostaining studies showed that PITX1 is present in both WT and CKO distal lung epithelium (Fig. 2a,b). Three Pitx2 isoforms exist a, b and c the latter of which is involved in Left/right asymmetry and is only expressed on the left side of the lung [22]. PITX2 (using antibodies recognizing all three isoforms) is normally found in distal epithelium and mesenchyme but is absent from PSMC around the bronchi (arrow in Fig. 2c), and as expected, PITX2 levels were found to be drastically reduced in the CKO mesenchyme (Fig. 2d). By contrast, PITX3 is expressed exclusively in the differentiated smooth muscle cells around the bronchi in both WT and CKO lungs (Fig. 2e–h), suggestive of a switch from PITX2 to PITX3 expression upon PSMC differentiation. Although the significance of this switch needs to be elucidated, our findings indicate a major impact on PITX2 expression at the protein level.

Bottom Line: The amplification but not differentiation of Fgf10-expressing parabronchial smooth muscle progenitor cells is drastically reduced.In the angioblast-endothelial lineage, however, only differentiation into mature endothelial cells is impaired.Taken together these findings reveal a hierarchy of gene activity involving ss-catenin and PITX, as important regulators of mesenchymal cell proliferation and differentiation.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology Program, Department of Surgery, Saban Research Institute of Childrens Hospital Los Angeles, Los Angeles, California, USA.

ABSTRACT

Background: The role of ss-catenin signaling in mesodermal lineage formation and differentiation has been elusive.

Methodology: To define the role of ss-catenin signaling in these processes, we used a Dermo1(Twist2)(Cre/+) line to target a floxed beta-catenin allele, throughout the embryonic mesenchyme. Strikingly, the Dermo1(Cre/+); beta-catenin(f/-) conditional Knock Out embryos largely phenocopy Pitx1(-/-)/Pitx2(-/-) double knockout embryos, suggesting that ss-catenin signaling in the mesenchyme depends mostly on the PITX family of transcription factors. We have dissected this relationship further in the developing lungs and find that mesenchymal deletion of beta-catenin differentially affects two major mesenchymal lineages. The amplification but not differentiation of Fgf10-expressing parabronchial smooth muscle progenitor cells is drastically reduced. In the angioblast-endothelial lineage, however, only differentiation into mature endothelial cells is impaired.

Conclusion: Taken together these findings reveal a hierarchy of gene activity involving ss-catenin and PITX, as important regulators of mesenchymal cell proliferation and differentiation.

Show MeSH
Related in: MedlinePlus