Limits...
Disruption of LTBP-4 function reduces TGF-beta activation and enhances BMP-4 signaling in the lung.

Koli K, Wempe F, Sterner-Kock A, Kantola A, Komor M, Hofmann WK, von Melchner H, Keski-Oja J - J. Cell Biol. (2004)

Bottom Line: These results suggested that TGF-beta activation but not secretion would be severely impaired in LTBP-4 -/- fibroblasts.Microarrays revealed increased expression of bone morphogenic protein (BMP)-4 and decreased expression of its inhibitor gremlin.Treatment with active TGF-beta1 rescued BMP-4 and gremlin expression to wild-type levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Virology, Haartman Institute and Helsinki University Hospital, University of Helsinki, 00014 Helsinki, Finland. katri.koli@helsinki.fi

ABSTRACT
Disruption of latent TGF-beta binding protein (LTBP)-4 expression in the mouse leads to abnormal lung development and colorectal cancer. Lung fibroblasts from these mice produced decreased amounts of active TGF-beta, whereas secretion of latent TGF-beta was significantly increased. Expression and secretion of TGF-beta2 and -beta3 increased considerably. These results suggested that TGF-beta activation but not secretion would be severely impaired in LTBP-4 -/- fibroblasts. Microarrays revealed increased expression of bone morphogenic protein (BMP)-4 and decreased expression of its inhibitor gremlin. This finding was accompanied by enhanced expression of BMP-4 target genes, inhibitors of differentiation 1 and 2, and increased deposition of fibronectin-rich extracellular matrix. Accordingly, increased expression of BMP-4 and decreased expression of gremlin were observed in mouse lung. Transfection of LTBP-4 rescued the -/- fibroblast phenotype, while LTBP-1 was inefficient. Treatment with active TGF-beta1 rescued BMP-4 and gremlin expression to wild-type levels. Our results indicate that the lack of LTBP-4-mediated targeting and activation of TGF-beta1 leads to enhanced BMP-4 signaling in mouse lung.

Show MeSH

Related in: MedlinePlus

BMP-4 induces matrix production in wt fibroblasts. (A) wt fibroblasts (+/+) were cultured in the presence of the indicated concentrations of BMP-4 and labeled amino acids for 2 d, followed by isolation of the ECM. Polypeptides of the ECM preparations were separated by SDS-PAGE under reducing conditions and visualized by fluorography. The migration of the molecular mass markers (kD) is indicated on the left. (B) Total RNA was isolated from cultured lung fibroblasts, and mRNA expression levels of CTGF, PAI-1, TGF-β2 and TGF-β3 were analyzed by Northern blotting. mRNA expression of a constant gene, GADPH, was used to control loading.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172518&req=5

fig8: BMP-4 induces matrix production in wt fibroblasts. (A) wt fibroblasts (+/+) were cultured in the presence of the indicated concentrations of BMP-4 and labeled amino acids for 2 d, followed by isolation of the ECM. Polypeptides of the ECM preparations were separated by SDS-PAGE under reducing conditions and visualized by fluorography. The migration of the molecular mass markers (kD) is indicated on the left. (B) Total RNA was isolated from cultured lung fibroblasts, and mRNA expression levels of CTGF, PAI-1, TGF-β2 and TGF-β3 were analyzed by Northern blotting. mRNA expression of a constant gene, GADPH, was used to control loading.

Mentions: BMP-4 induces fibronectin synthesis and ECM assembly in rat osteoblasts by increasing the synthesis and clustering of α5β1 integrins (Tang et al., 2003). To further test if BMP-4 is involved in the regulation of ECM accumulation, we treated wt lung fibroblasts with increasing concentrations of BMP-4 for 2 d and analyzed their ECM production. A dose-dependent increase in the accumulation of ECM occurred in BMP-4–treated cells (Fig. 8 A). The role of BMP-4 in the regulation of CTGF, PAI-1, TGF-β2, and TGF-β3 mRNA expression was then analyzed by Northern hybridization analyses. wt fibroblasts were treated with 5 or 50 ng/ml of BMP-4 for 24 h followed by RNA isolation and Northern analyses. BMP-4 at 50 ng/ml induced CTGF and TGF-β3 mRNA levels three- to fourfold, whereas PAI-1 and TGF-β2 mRNA levels were unchanged (Fig. 7 B). This result is in accordance with the data indicating that the inhibition of BMP-4 signaling in −/− fibroblasts by reexpression of gremlin down-regulates CTGF and TGF-β3 mRNA expression levels.


Disruption of LTBP-4 function reduces TGF-beta activation and enhances BMP-4 signaling in the lung.

Koli K, Wempe F, Sterner-Kock A, Kantola A, Komor M, Hofmann WK, von Melchner H, Keski-Oja J - J. Cell Biol. (2004)

BMP-4 induces matrix production in wt fibroblasts. (A) wt fibroblasts (+/+) were cultured in the presence of the indicated concentrations of BMP-4 and labeled amino acids for 2 d, followed by isolation of the ECM. Polypeptides of the ECM preparations were separated by SDS-PAGE under reducing conditions and visualized by fluorography. The migration of the molecular mass markers (kD) is indicated on the left. (B) Total RNA was isolated from cultured lung fibroblasts, and mRNA expression levels of CTGF, PAI-1, TGF-β2 and TGF-β3 were analyzed by Northern blotting. mRNA expression of a constant gene, GADPH, was used to control loading.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172518&req=5

fig8: BMP-4 induces matrix production in wt fibroblasts. (A) wt fibroblasts (+/+) were cultured in the presence of the indicated concentrations of BMP-4 and labeled amino acids for 2 d, followed by isolation of the ECM. Polypeptides of the ECM preparations were separated by SDS-PAGE under reducing conditions and visualized by fluorography. The migration of the molecular mass markers (kD) is indicated on the left. (B) Total RNA was isolated from cultured lung fibroblasts, and mRNA expression levels of CTGF, PAI-1, TGF-β2 and TGF-β3 were analyzed by Northern blotting. mRNA expression of a constant gene, GADPH, was used to control loading.
Mentions: BMP-4 induces fibronectin synthesis and ECM assembly in rat osteoblasts by increasing the synthesis and clustering of α5β1 integrins (Tang et al., 2003). To further test if BMP-4 is involved in the regulation of ECM accumulation, we treated wt lung fibroblasts with increasing concentrations of BMP-4 for 2 d and analyzed their ECM production. A dose-dependent increase in the accumulation of ECM occurred in BMP-4–treated cells (Fig. 8 A). The role of BMP-4 in the regulation of CTGF, PAI-1, TGF-β2, and TGF-β3 mRNA expression was then analyzed by Northern hybridization analyses. wt fibroblasts were treated with 5 or 50 ng/ml of BMP-4 for 24 h followed by RNA isolation and Northern analyses. BMP-4 at 50 ng/ml induced CTGF and TGF-β3 mRNA levels three- to fourfold, whereas PAI-1 and TGF-β2 mRNA levels were unchanged (Fig. 7 B). This result is in accordance with the data indicating that the inhibition of BMP-4 signaling in −/− fibroblasts by reexpression of gremlin down-regulates CTGF and TGF-β3 mRNA expression levels.

Bottom Line: These results suggested that TGF-beta activation but not secretion would be severely impaired in LTBP-4 -/- fibroblasts.Microarrays revealed increased expression of bone morphogenic protein (BMP)-4 and decreased expression of its inhibitor gremlin.Treatment with active TGF-beta1 rescued BMP-4 and gremlin expression to wild-type levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Virology, Haartman Institute and Helsinki University Hospital, University of Helsinki, 00014 Helsinki, Finland. katri.koli@helsinki.fi

ABSTRACT
Disruption of latent TGF-beta binding protein (LTBP)-4 expression in the mouse leads to abnormal lung development and colorectal cancer. Lung fibroblasts from these mice produced decreased amounts of active TGF-beta, whereas secretion of latent TGF-beta was significantly increased. Expression and secretion of TGF-beta2 and -beta3 increased considerably. These results suggested that TGF-beta activation but not secretion would be severely impaired in LTBP-4 -/- fibroblasts. Microarrays revealed increased expression of bone morphogenic protein (BMP)-4 and decreased expression of its inhibitor gremlin. This finding was accompanied by enhanced expression of BMP-4 target genes, inhibitors of differentiation 1 and 2, and increased deposition of fibronectin-rich extracellular matrix. Accordingly, increased expression of BMP-4 and decreased expression of gremlin were observed in mouse lung. Transfection of LTBP-4 rescued the -/- fibroblast phenotype, while LTBP-1 was inefficient. Treatment with active TGF-beta1 rescued BMP-4 and gremlin expression to wild-type levels. Our results indicate that the lack of LTBP-4-mediated targeting and activation of TGF-beta1 leads to enhanced BMP-4 signaling in mouse lung.

Show MeSH
Related in: MedlinePlus