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Altered lung morphogenesis, epithelial cell differentiation and mechanics in mice deficient in the Wnt/β-catenin antagonist Chibby.

Love D, Li FQ, Burke MC, Cyge B, Ohmitsu M, Cabello J, Larson JE, Brody SL, Cohen JC, Takemaru K - PLoS ONE (2010)

Bottom Line: Notably, Cby protein is prominently associated with the centrosome/basal body microtubule structures in embryonic lung epithelial progenitor cells, and later enriches as discrete foci at the base of motile cilia in airway ciliated cells.At birth, Cby(-/-) lungs are grossly normal but spontaneously develop alveolar airspace enlargement with reduced proliferation and abnormal differentiation of lung epithelial cells, resulting in altered pulmonary function.Collectively, our results demonstrate that Cby facilitates proper postnatal lung development and function.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacological Sciences, SUNY at Stony Brook, Stony Brook, New York, United States of America.

ABSTRACT
The canonical Wnt/β-catenin pathway plays crucial roles in various aspects of lung morphogenesis and regeneration/repair. Here, we examined the lung phenotype and function in mice lacking the Wnt/β-catenin antagonist Chibby (Cby). In support of its inhibitory role in canonical Wnt signaling, expression of β-catenin target genes is elevated in the Cby(-/-) lung. Notably, Cby protein is prominently associated with the centrosome/basal body microtubule structures in embryonic lung epithelial progenitor cells, and later enriches as discrete foci at the base of motile cilia in airway ciliated cells. At birth, Cby(-/-) lungs are grossly normal but spontaneously develop alveolar airspace enlargement with reduced proliferation and abnormal differentiation of lung epithelial cells, resulting in altered pulmonary function. Consistent with the Cby expression pattern, airway ciliated cells exhibit a marked paucity of motile cilia with apparent failure of basal body docking. Moreover, we demonstrate that Cby is a direct downstream target for the master ciliogenesis transcription factor Foxj1. Collectively, our results demonstrate that Cby facilitates proper postnatal lung development and function.

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Defective differentiation and morphology of alveolar epithelial cells in Cby−/− mice.(A) Peripheral lung sections were co-immunostained with antibodies against the type II pneumocyte marker proSP-C (red) and type I pneumocyte marker Aqp5 (green). Nuclei were detected with DAPI. The immunostained area was quantified by counting the number of pixels present. Values represent means ± SE. Student's t-test; *P<0.05, **P<0.001. (B–E) TEM was performed on adult distal lungs from Cby+/+ (B, D) and Cby−/− (C, E) mice. In the alveolar epithelium of Cby+/+ mice, squamous type I pneumocytes and cuboidal type II pneumocytes containing lamellar bodies were observed. In Cby−/− lungs, the thickening of the cytoplasmic extension of type I cells was noted. Type II cells also exhibited morphological defects and frequently contained an increased number of lamellar bodies. Lipid-laden interstitial fibroblasts were often found in Cby−/− lungs (C). Black arrowheads point to microvilli (D and E). P1, type I pneumocytes; P2, type II pneumocytes; LB, lamellar bodies; C, capillaries; R, red blood cells; Av, alveolar airspace; M, mitochondria; asterisks, lipid droplets. Scale bars: (A) 50 µm; (B, C) 10 µm; (D, E) 5 µm.
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pone-0013600-g006: Defective differentiation and morphology of alveolar epithelial cells in Cby−/− mice.(A) Peripheral lung sections were co-immunostained with antibodies against the type II pneumocyte marker proSP-C (red) and type I pneumocyte marker Aqp5 (green). Nuclei were detected with DAPI. The immunostained area was quantified by counting the number of pixels present. Values represent means ± SE. Student's t-test; *P<0.05, **P<0.001. (B–E) TEM was performed on adult distal lungs from Cby+/+ (B, D) and Cby−/− (C, E) mice. In the alveolar epithelium of Cby+/+ mice, squamous type I pneumocytes and cuboidal type II pneumocytes containing lamellar bodies were observed. In Cby−/− lungs, the thickening of the cytoplasmic extension of type I cells was noted. Type II cells also exhibited morphological defects and frequently contained an increased number of lamellar bodies. Lipid-laden interstitial fibroblasts were often found in Cby−/− lungs (C). Black arrowheads point to microvilli (D and E). P1, type I pneumocytes; P2, type II pneumocytes; LB, lamellar bodies; C, capillaries; R, red blood cells; Av, alveolar airspace; M, mitochondria; asterisks, lipid droplets. Scale bars: (A) 50 µm; (B, C) 10 µm; (D, E) 5 µm.

Mentions: The alveolar epithelium consists of two major cell types, squamous type I and cuboidal type II pneumocytes [29], [30]. Type I cells are directly involved in gas exchange, whereas type II cells secrete pulmonary surfactants and also serve as progenitors for type I cells. Immunostaining revealed that Cby−/− lungs had increased expression of pro-surfactant protein C (proSP-C), a marker for type II cells, in comparison with Cby+/+ controls (Figure 6A). Quantitative assessment of proSP-C immunostaining by pixel counts showed a substantial difference between Cby+/+ (1,437±477) and Cby−/− (47,660±4,796) mice (P<0.001). Conversely, expression of aquaporin 5 (Aqp5), a terminally differentiated type I cell marker, was reduced in Cby−/− lungs. Quantitative analysis by pixel counts also showed a significant difference between Cby+/+ (34,320±8,715) and Cby−/− (4,454±2,066) mice (P<0.05).


Altered lung morphogenesis, epithelial cell differentiation and mechanics in mice deficient in the Wnt/β-catenin antagonist Chibby.

Love D, Li FQ, Burke MC, Cyge B, Ohmitsu M, Cabello J, Larson JE, Brody SL, Cohen JC, Takemaru K - PLoS ONE (2010)

Defective differentiation and morphology of alveolar epithelial cells in Cby−/− mice.(A) Peripheral lung sections were co-immunostained with antibodies against the type II pneumocyte marker proSP-C (red) and type I pneumocyte marker Aqp5 (green). Nuclei were detected with DAPI. The immunostained area was quantified by counting the number of pixels present. Values represent means ± SE. Student's t-test; *P<0.05, **P<0.001. (B–E) TEM was performed on adult distal lungs from Cby+/+ (B, D) and Cby−/− (C, E) mice. In the alveolar epithelium of Cby+/+ mice, squamous type I pneumocytes and cuboidal type II pneumocytes containing lamellar bodies were observed. In Cby−/− lungs, the thickening of the cytoplasmic extension of type I cells was noted. Type II cells also exhibited morphological defects and frequently contained an increased number of lamellar bodies. Lipid-laden interstitial fibroblasts were often found in Cby−/− lungs (C). Black arrowheads point to microvilli (D and E). P1, type I pneumocytes; P2, type II pneumocytes; LB, lamellar bodies; C, capillaries; R, red blood cells; Av, alveolar airspace; M, mitochondria; asterisks, lipid droplets. Scale bars: (A) 50 µm; (B, C) 10 µm; (D, E) 5 µm.
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pone-0013600-g006: Defective differentiation and morphology of alveolar epithelial cells in Cby−/− mice.(A) Peripheral lung sections were co-immunostained with antibodies against the type II pneumocyte marker proSP-C (red) and type I pneumocyte marker Aqp5 (green). Nuclei were detected with DAPI. The immunostained area was quantified by counting the number of pixels present. Values represent means ± SE. Student's t-test; *P<0.05, **P<0.001. (B–E) TEM was performed on adult distal lungs from Cby+/+ (B, D) and Cby−/− (C, E) mice. In the alveolar epithelium of Cby+/+ mice, squamous type I pneumocytes and cuboidal type II pneumocytes containing lamellar bodies were observed. In Cby−/− lungs, the thickening of the cytoplasmic extension of type I cells was noted. Type II cells also exhibited morphological defects and frequently contained an increased number of lamellar bodies. Lipid-laden interstitial fibroblasts were often found in Cby−/− lungs (C). Black arrowheads point to microvilli (D and E). P1, type I pneumocytes; P2, type II pneumocytes; LB, lamellar bodies; C, capillaries; R, red blood cells; Av, alveolar airspace; M, mitochondria; asterisks, lipid droplets. Scale bars: (A) 50 µm; (B, C) 10 µm; (D, E) 5 µm.
Mentions: The alveolar epithelium consists of two major cell types, squamous type I and cuboidal type II pneumocytes [29], [30]. Type I cells are directly involved in gas exchange, whereas type II cells secrete pulmonary surfactants and also serve as progenitors for type I cells. Immunostaining revealed that Cby−/− lungs had increased expression of pro-surfactant protein C (proSP-C), a marker for type II cells, in comparison with Cby+/+ controls (Figure 6A). Quantitative assessment of proSP-C immunostaining by pixel counts showed a substantial difference between Cby+/+ (1,437±477) and Cby−/− (47,660±4,796) mice (P<0.001). Conversely, expression of aquaporin 5 (Aqp5), a terminally differentiated type I cell marker, was reduced in Cby−/− lungs. Quantitative analysis by pixel counts also showed a significant difference between Cby+/+ (34,320±8,715) and Cby−/− (4,454±2,066) mice (P<0.05).

Bottom Line: Notably, Cby protein is prominently associated with the centrosome/basal body microtubule structures in embryonic lung epithelial progenitor cells, and later enriches as discrete foci at the base of motile cilia in airway ciliated cells.At birth, Cby(-/-) lungs are grossly normal but spontaneously develop alveolar airspace enlargement with reduced proliferation and abnormal differentiation of lung epithelial cells, resulting in altered pulmonary function.Collectively, our results demonstrate that Cby facilitates proper postnatal lung development and function.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacological Sciences, SUNY at Stony Brook, Stony Brook, New York, United States of America.

ABSTRACT
The canonical Wnt/β-catenin pathway plays crucial roles in various aspects of lung morphogenesis and regeneration/repair. Here, we examined the lung phenotype and function in mice lacking the Wnt/β-catenin antagonist Chibby (Cby). In support of its inhibitory role in canonical Wnt signaling, expression of β-catenin target genes is elevated in the Cby(-/-) lung. Notably, Cby protein is prominently associated with the centrosome/basal body microtubule structures in embryonic lung epithelial progenitor cells, and later enriches as discrete foci at the base of motile cilia in airway ciliated cells. At birth, Cby(-/-) lungs are grossly normal but spontaneously develop alveolar airspace enlargement with reduced proliferation and abnormal differentiation of lung epithelial cells, resulting in altered pulmonary function. Consistent with the Cby expression pattern, airway ciliated cells exhibit a marked paucity of motile cilia with apparent failure of basal body docking. Moreover, we demonstrate that Cby is a direct downstream target for the master ciliogenesis transcription factor Foxj1. Collectively, our results demonstrate that Cby facilitates proper postnatal lung development and function.

Show MeSH
Related in: MedlinePlus