Upregulation of TGF-β-induced tissue transglutaminase expression by PI3K-Akt pathway activation in human subconjunctival fibroblasts

Sun Ah Jung, Hyung Keun Lee, Jin Sook Yoon, Sung Joo Kim, Chan Yoon Kim, Heesang Song, Ki Chul Hwang, Jong Bok Lee, Joon H. Lee

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

PURPOSE. Excessive scarring in subconjunctival tissues after filtering surgery seems to be characterized by aberrant extracellular matrix (ECM) production, and tissue transglutaminase (tTgase) plays an important role in this process. In the present study, the effects of transforming growth factor (TGF)-β2 on the expression of tTgase, its activity in subconjunctival fibroblasts and whether the effects of TGF-β are mediated by prosurvival signaling pathways were examined. METHODS. Primary subconjunctival fibroblasts treated with TGF-β2 were examined for the expression of tTgase with Western blot analysis. The modulation of extracellular tTgase activity by TGF-β2 was measured by both the formation of fibronectin polymers and the ECM protein incorporation of fluorescein cadaverine. The expression of tTgase was analyzed by immunofluorescence staining and Western blot analysis of subconjunctival fibroblasts that were transiently transfected with an Akt dominant negative mutant gene or were treated with an Akt inhibitor or tTgase siRNA. RESULTS. Treatment of subconjunctival fibroblasts with TGF-β2 caused an increase in activation and expression of tTgase. The effects of TGF-β stimulation of subconjunctival fibroblasts were twofold, causing both rapid activation of the ERK pathway within minutes of treatment and a more delayed activation of the phosphatidylinositol3-kinase-protein kinase B (PKB)/Akt pathway; however, only Akt activation was necessary for TGF-β-induced tTgase expression. Transient transfection of subconjunctival fibroblasts with an Akt dominant negative mutant gene, or treatment with an Akt inhibitor (but not with an ERK inhibitor) or tTgase siRNA led to decreased activation and expression of tTgase. CONCLUSIONS. TGF-β2 activated the PI3K-Akt pathway, and this activation was essential for the expression and activity of tTgase in subconjunctival fibroblasts. The results indicate a novel biological function of the PI3K-Akt pathway in subconjunctival fibroblasts. Elevated expression and activity of tTgase may play an important role in the pathogenesis of diseases related to wound healing and fibrogenic reactions in subconjunctival fibroblasts.

Original languageEnglish
Pages (from-to)1952-1958
Number of pages7
JournalInvestigative Ophthalmology and Visual Science
Volume48
Issue number5
DOIs
Publication statusPublished - 2007 May 1

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Transforming Growth Factors
Phosphatidylinositol 3-Kinases
Up-Regulation
Fibroblasts
Small Interfering RNA
transglutaminase 2
Western Blotting
Cadaverine
Filtering Surgery
Proto-Oncogene Proteins c-akt
MAP Kinase Signaling System
Extracellular Matrix Proteins
Fluorescein
Fibronectins
Wound Healing
Genes
Cicatrix
Fluorescent Antibody Technique
Extracellular Matrix
Transfection

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Jung, Sun Ah ; Lee, Hyung Keun ; Yoon, Jin Sook ; Kim, Sung Joo ; Kim, Chan Yoon ; Song, Heesang ; Hwang, Ki Chul ; Lee, Jong Bok ; Lee, Joon H. / Upregulation of TGF-β-induced tissue transglutaminase expression by PI3K-Akt pathway activation in human subconjunctival fibroblasts. In: Investigative Ophthalmology and Visual Science. 2007 ; Vol. 48, No. 5. pp. 1952-1958.
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title = "Upregulation of TGF-β-induced tissue transglutaminase expression by PI3K-Akt pathway activation in human subconjunctival fibroblasts",
abstract = "PURPOSE. Excessive scarring in subconjunctival tissues after filtering surgery seems to be characterized by aberrant extracellular matrix (ECM) production, and tissue transglutaminase (tTgase) plays an important role in this process. In the present study, the effects of transforming growth factor (TGF)-β2 on the expression of tTgase, its activity in subconjunctival fibroblasts and whether the effects of TGF-β are mediated by prosurvival signaling pathways were examined. METHODS. Primary subconjunctival fibroblasts treated with TGF-β2 were examined for the expression of tTgase with Western blot analysis. The modulation of extracellular tTgase activity by TGF-β2 was measured by both the formation of fibronectin polymers and the ECM protein incorporation of fluorescein cadaverine. The expression of tTgase was analyzed by immunofluorescence staining and Western blot analysis of subconjunctival fibroblasts that were transiently transfected with an Akt dominant negative mutant gene or were treated with an Akt inhibitor or tTgase siRNA. RESULTS. Treatment of subconjunctival fibroblasts with TGF-β2 caused an increase in activation and expression of tTgase. The effects of TGF-β stimulation of subconjunctival fibroblasts were twofold, causing both rapid activation of the ERK pathway within minutes of treatment and a more delayed activation of the phosphatidylinositol3-kinase-protein kinase B (PKB)/Akt pathway; however, only Akt activation was necessary for TGF-β-induced tTgase expression. Transient transfection of subconjunctival fibroblasts with an Akt dominant negative mutant gene, or treatment with an Akt inhibitor (but not with an ERK inhibitor) or tTgase siRNA led to decreased activation and expression of tTgase. CONCLUSIONS. TGF-β2 activated the PI3K-Akt pathway, and this activation was essential for the expression and activity of tTgase in subconjunctival fibroblasts. The results indicate a novel biological function of the PI3K-Akt pathway in subconjunctival fibroblasts. Elevated expression and activity of tTgase may play an important role in the pathogenesis of diseases related to wound healing and fibrogenic reactions in subconjunctival fibroblasts.",
author = "Jung, {Sun Ah} and Lee, {Hyung Keun} and Yoon, {Jin Sook} and Kim, {Sung Joo} and Kim, {Chan Yoon} and Heesang Song and Hwang, {Ki Chul} and Lee, {Jong Bok} and Lee, {Joon H.}",
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Upregulation of TGF-β-induced tissue transglutaminase expression by PI3K-Akt pathway activation in human subconjunctival fibroblasts. / Jung, Sun Ah; Lee, Hyung Keun; Yoon, Jin Sook; Kim, Sung Joo; Kim, Chan Yoon; Song, Heesang; Hwang, Ki Chul; Lee, Jong Bok; Lee, Joon H.

In: Investigative Ophthalmology and Visual Science, Vol. 48, No. 5, 01.05.2007, p. 1952-1958.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Upregulation of TGF-β-induced tissue transglutaminase expression by PI3K-Akt pathway activation in human subconjunctival fibroblasts

AU - Jung, Sun Ah

AU - Lee, Hyung Keun

AU - Yoon, Jin Sook

AU - Kim, Sung Joo

AU - Kim, Chan Yoon

AU - Song, Heesang

AU - Hwang, Ki Chul

AU - Lee, Jong Bok

AU - Lee, Joon H.

PY - 2007/5/1

Y1 - 2007/5/1

N2 - PURPOSE. Excessive scarring in subconjunctival tissues after filtering surgery seems to be characterized by aberrant extracellular matrix (ECM) production, and tissue transglutaminase (tTgase) plays an important role in this process. In the present study, the effects of transforming growth factor (TGF)-β2 on the expression of tTgase, its activity in subconjunctival fibroblasts and whether the effects of TGF-β are mediated by prosurvival signaling pathways were examined. METHODS. Primary subconjunctival fibroblasts treated with TGF-β2 were examined for the expression of tTgase with Western blot analysis. The modulation of extracellular tTgase activity by TGF-β2 was measured by both the formation of fibronectin polymers and the ECM protein incorporation of fluorescein cadaverine. The expression of tTgase was analyzed by immunofluorescence staining and Western blot analysis of subconjunctival fibroblasts that were transiently transfected with an Akt dominant negative mutant gene or were treated with an Akt inhibitor or tTgase siRNA. RESULTS. Treatment of subconjunctival fibroblasts with TGF-β2 caused an increase in activation and expression of tTgase. The effects of TGF-β stimulation of subconjunctival fibroblasts were twofold, causing both rapid activation of the ERK pathway within minutes of treatment and a more delayed activation of the phosphatidylinositol3-kinase-protein kinase B (PKB)/Akt pathway; however, only Akt activation was necessary for TGF-β-induced tTgase expression. Transient transfection of subconjunctival fibroblasts with an Akt dominant negative mutant gene, or treatment with an Akt inhibitor (but not with an ERK inhibitor) or tTgase siRNA led to decreased activation and expression of tTgase. CONCLUSIONS. TGF-β2 activated the PI3K-Akt pathway, and this activation was essential for the expression and activity of tTgase in subconjunctival fibroblasts. The results indicate a novel biological function of the PI3K-Akt pathway in subconjunctival fibroblasts. Elevated expression and activity of tTgase may play an important role in the pathogenesis of diseases related to wound healing and fibrogenic reactions in subconjunctival fibroblasts.

AB - PURPOSE. Excessive scarring in subconjunctival tissues after filtering surgery seems to be characterized by aberrant extracellular matrix (ECM) production, and tissue transglutaminase (tTgase) plays an important role in this process. In the present study, the effects of transforming growth factor (TGF)-β2 on the expression of tTgase, its activity in subconjunctival fibroblasts and whether the effects of TGF-β are mediated by prosurvival signaling pathways were examined. METHODS. Primary subconjunctival fibroblasts treated with TGF-β2 were examined for the expression of tTgase with Western blot analysis. The modulation of extracellular tTgase activity by TGF-β2 was measured by both the formation of fibronectin polymers and the ECM protein incorporation of fluorescein cadaverine. The expression of tTgase was analyzed by immunofluorescence staining and Western blot analysis of subconjunctival fibroblasts that were transiently transfected with an Akt dominant negative mutant gene or were treated with an Akt inhibitor or tTgase siRNA. RESULTS. Treatment of subconjunctival fibroblasts with TGF-β2 caused an increase in activation and expression of tTgase. The effects of TGF-β stimulation of subconjunctival fibroblasts were twofold, causing both rapid activation of the ERK pathway within minutes of treatment and a more delayed activation of the phosphatidylinositol3-kinase-protein kinase B (PKB)/Akt pathway; however, only Akt activation was necessary for TGF-β-induced tTgase expression. Transient transfection of subconjunctival fibroblasts with an Akt dominant negative mutant gene, or treatment with an Akt inhibitor (but not with an ERK inhibitor) or tTgase siRNA led to decreased activation and expression of tTgase. CONCLUSIONS. TGF-β2 activated the PI3K-Akt pathway, and this activation was essential for the expression and activity of tTgase in subconjunctival fibroblasts. The results indicate a novel biological function of the PI3K-Akt pathway in subconjunctival fibroblasts. Elevated expression and activity of tTgase may play an important role in the pathogenesis of diseases related to wound healing and fibrogenic reactions in subconjunctival fibroblasts.

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