Pretranslational regulation of type I collagen, fibronectin, and a 50-kilodalton noncollagenous extracellular protein by dexamethasone in rat fibroblasts

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Abstract

The effect of dexamethasone on the synthesis of total cellular and extracellular proteins and specifically on the synthesis of type I procollagen chains, fibronectin, and a 50-kDa extracellular noncollagenous polypeptide was examined in cultured rat dermal fibroblasts. A slight but consistent inhibition of total protein synthesis by dexamethasone was dose and time dependent. Treatment of cells with 1 μM dexamethasone for 24 h while abolishing procollagen synthesis nearly completely (<95%) had the opposite effect (5-7-fold increase) on the synthesis of an extracellular noncollagenous 50-kDa polypeptide. Dexamethasone did not significantly affect the rates of synthesis of fibronectin. Cell-free translation of mRNA from dexamethasone-treated cells revealed corresponding changes in the steady-state levels of functional mRNAs coding for procollagens, the 50-kDa polypeptide, and fibronectin. Northern blot hybridization using nick-translated cDNA plasmids coding for pro-α1(I), fibronectin, and cytoplasmic β-actin mRNA corroborated the data obtained from cell-free translation experiments. Run-off transcription assays using nuclei from cells treated with 1 μM dexamethasone for 24 h revealed that glucocorticoid treatment did not significantly affect the rate of transcription of type I collagen genes; similarly, the rate of transcription of fibronectin and cytoplasmic β-actin genes also remained unchanged under these conditions. An analysis of the kinetics of decay of radiolabeled mRNA coding for pro-α1(I), pro-α2(I), and fibronectin in dexamethasone-treated cells revealed that procollagen mRNAs were turned over at an accelerated rate in glucocorticoid-treated cells. These data suggest that dexamethasone regulates type I collagen gene expression by preferentially decreasing the stability of pro-α1(I) and pro-α2(I) mRNAs. although dexamethasone increased the levels of translatable mRNAs coding for a 50-kDa polypeptide, the molecular mechanism(s) of how hormone exerts this effect remains unknown.

Original languageEnglish (US)
Pages (from-to)4677-4684
Number of pages8
JournalJournal of Biological Chemistry
Volume261
Issue number10
StatePublished - Dec 1 1986
Externally publishedYes

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Fibroblasts
Collagen Type I
Fibronectins
Dexamethasone
Rats
Messenger RNA
Procollagen
Proteins
Transcription
Cells
Peptides
Glucocorticoids
Actins
Genes
RNA Stability
Protein Biosynthesis
Cell Nucleus
Gene expression
Northern Blotting
Assays

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

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title = "Pretranslational regulation of type I collagen, fibronectin, and a 50-kilodalton noncollagenous extracellular protein by dexamethasone in rat fibroblasts",
abstract = "The effect of dexamethasone on the synthesis of total cellular and extracellular proteins and specifically on the synthesis of type I procollagen chains, fibronectin, and a 50-kDa extracellular noncollagenous polypeptide was examined in cultured rat dermal fibroblasts. A slight but consistent inhibition of total protein synthesis by dexamethasone was dose and time dependent. Treatment of cells with 1 μM dexamethasone for 24 h while abolishing procollagen synthesis nearly completely (<95{\%}) had the opposite effect (5-7-fold increase) on the synthesis of an extracellular noncollagenous 50-kDa polypeptide. Dexamethasone did not significantly affect the rates of synthesis of fibronectin. Cell-free translation of mRNA from dexamethasone-treated cells revealed corresponding changes in the steady-state levels of functional mRNAs coding for procollagens, the 50-kDa polypeptide, and fibronectin. Northern blot hybridization using nick-translated cDNA plasmids coding for pro-α1(I), fibronectin, and cytoplasmic β-actin mRNA corroborated the data obtained from cell-free translation experiments. Run-off transcription assays using nuclei from cells treated with 1 μM dexamethasone for 24 h revealed that glucocorticoid treatment did not significantly affect the rate of transcription of type I collagen genes; similarly, the rate of transcription of fibronectin and cytoplasmic β-actin genes also remained unchanged under these conditions. An analysis of the kinetics of decay of radiolabeled mRNA coding for pro-α1(I), pro-α2(I), and fibronectin in dexamethasone-treated cells revealed that procollagen mRNAs were turned over at an accelerated rate in glucocorticoid-treated cells. These data suggest that dexamethasone regulates type I collagen gene expression by preferentially decreasing the stability of pro-α1(I) and pro-α2(I) mRNAs. although dexamethasone increased the levels of translatable mRNAs coding for a 50-kDa polypeptide, the molecular mechanism(s) of how hormone exerts this effect remains unknown.",
author = "Rajendra Raghow and D. Gossage and Andrew Kang",
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T1 - Pretranslational regulation of type I collagen, fibronectin, and a 50-kilodalton noncollagenous extracellular protein by dexamethasone in rat fibroblasts

AU - Raghow, Rajendra

AU - Gossage, D.

AU - Kang, Andrew

PY - 1986/12/1

Y1 - 1986/12/1

N2 - The effect of dexamethasone on the synthesis of total cellular and extracellular proteins and specifically on the synthesis of type I procollagen chains, fibronectin, and a 50-kDa extracellular noncollagenous polypeptide was examined in cultured rat dermal fibroblasts. A slight but consistent inhibition of total protein synthesis by dexamethasone was dose and time dependent. Treatment of cells with 1 μM dexamethasone for 24 h while abolishing procollagen synthesis nearly completely (<95%) had the opposite effect (5-7-fold increase) on the synthesis of an extracellular noncollagenous 50-kDa polypeptide. Dexamethasone did not significantly affect the rates of synthesis of fibronectin. Cell-free translation of mRNA from dexamethasone-treated cells revealed corresponding changes in the steady-state levels of functional mRNAs coding for procollagens, the 50-kDa polypeptide, and fibronectin. Northern blot hybridization using nick-translated cDNA plasmids coding for pro-α1(I), fibronectin, and cytoplasmic β-actin mRNA corroborated the data obtained from cell-free translation experiments. Run-off transcription assays using nuclei from cells treated with 1 μM dexamethasone for 24 h revealed that glucocorticoid treatment did not significantly affect the rate of transcription of type I collagen genes; similarly, the rate of transcription of fibronectin and cytoplasmic β-actin genes also remained unchanged under these conditions. An analysis of the kinetics of decay of radiolabeled mRNA coding for pro-α1(I), pro-α2(I), and fibronectin in dexamethasone-treated cells revealed that procollagen mRNAs were turned over at an accelerated rate in glucocorticoid-treated cells. These data suggest that dexamethasone regulates type I collagen gene expression by preferentially decreasing the stability of pro-α1(I) and pro-α2(I) mRNAs. although dexamethasone increased the levels of translatable mRNAs coding for a 50-kDa polypeptide, the molecular mechanism(s) of how hormone exerts this effect remains unknown.

AB - The effect of dexamethasone on the synthesis of total cellular and extracellular proteins and specifically on the synthesis of type I procollagen chains, fibronectin, and a 50-kDa extracellular noncollagenous polypeptide was examined in cultured rat dermal fibroblasts. A slight but consistent inhibition of total protein synthesis by dexamethasone was dose and time dependent. Treatment of cells with 1 μM dexamethasone for 24 h while abolishing procollagen synthesis nearly completely (<95%) had the opposite effect (5-7-fold increase) on the synthesis of an extracellular noncollagenous 50-kDa polypeptide. Dexamethasone did not significantly affect the rates of synthesis of fibronectin. Cell-free translation of mRNA from dexamethasone-treated cells revealed corresponding changes in the steady-state levels of functional mRNAs coding for procollagens, the 50-kDa polypeptide, and fibronectin. Northern blot hybridization using nick-translated cDNA plasmids coding for pro-α1(I), fibronectin, and cytoplasmic β-actin mRNA corroborated the data obtained from cell-free translation experiments. Run-off transcription assays using nuclei from cells treated with 1 μM dexamethasone for 24 h revealed that glucocorticoid treatment did not significantly affect the rate of transcription of type I collagen genes; similarly, the rate of transcription of fibronectin and cytoplasmic β-actin genes also remained unchanged under these conditions. An analysis of the kinetics of decay of radiolabeled mRNA coding for pro-α1(I), pro-α2(I), and fibronectin in dexamethasone-treated cells revealed that procollagen mRNAs were turned over at an accelerated rate in glucocorticoid-treated cells. These data suggest that dexamethasone regulates type I collagen gene expression by preferentially decreasing the stability of pro-α1(I) and pro-α2(I) mRNAs. although dexamethasone increased the levels of translatable mRNAs coding for a 50-kDa polypeptide, the molecular mechanism(s) of how hormone exerts this effect remains unknown.

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