Transforming growth factor-β inhibition of proteasomal activity: A potential mechanism of growth arrest

Laura Tadlock, Yoko Yamagiwa, James Hawker, Carla Marienfeld, Tushar C Patel

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Although the proteasome plays a critical role in the controlled degradation of proteins involved in cell cycle control, the direct modulation of proteasomal function by growth regulatory signaling has not yet been demonstrated. We assessed the effect of transforming growth factor (TGF)-β, a potent inhibitor of cell growth, on proteasomal function. TGF-β selectively decreased hydrolysis of the proteasomal substrate Cbz-Leu-Leu-Leu-7-amido-4-methyl-coumarin (z-LLL-AMC) in a concentration-dependent manner but did not inhibit hydrolysis of other substrates Suc-Leu-Leu-Val-Tyr-AMC (suc-LLVY-AMC) or Cbz-Leu-Leu-Glu-AMC (z-LLE-AMC). An increase in intracellular oxidative injury occurred during incubation with TGF-β. Furthermore, in vitro hydrolysis of z-LLL-AMC, but not suc-LLVY-AMC, was decreased by hydrogen peroxide. TGF-β did not increase cellular expression of heat shock protein (HSP)90, a potent inhibitor of z-LLL-AMC hydrolysis in vitro. The physiological relevance of TGF-β inhibition of proteasomal activity was studied by assessing the role of z-LLL-AMC hydrolysis on cyclin-dependent kinase inhibitor expression and cell growth. TGF-β increased expression of p27KIP1 but did not alter expression of p21WAF1 or p16INK4A. The peptide aldehyde Cbz-Leu-Leu-leucinal (LLL-CHO or MG132) potently inhibited z-LLL-AMC hydrolysis in cell extracts as well as increasing p27KIP1 and decreasing cell proliferation. Thus growth inhibition by TGF-β decreases a specific proteasomal activity via an HSP90-independent mechanism that may involve oxidative inactivation or modulation of proteasomal subunit composition and results in altered cellular expression of key cell cycle regulatory proteins such as p27KIP1.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume285
Issue number2 54-2
StatePublished - Aug 1 2003
Externally publishedYes

Fingerprint

Transforming Growth Factors
Hydrolysis
Growth
Growth Inhibitors
leucylleucine
Modulation
HSP90 Heat-Shock Proteins
Cell Cycle Proteins
Cyclin-Dependent Kinases
Cell proliferation
Cell growth
Proteasome Endopeptidase Complex
Substrates
Cell Cycle Checkpoints
Cell Extracts
Aldehydes
Hydrogen Peroxide
Proteolysis
Cells
Cell Proliferation

Keywords

  • Cell cycle regulation
  • Cytokine
  • Heat shock protein
  • Oxidative stress

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

Transforming growth factor-β inhibition of proteasomal activity : A potential mechanism of growth arrest. / Tadlock, Laura; Yamagiwa, Yoko; Hawker, James; Marienfeld, Carla; Patel, Tushar C.

In: American Journal of Physiology - Cell Physiology, Vol. 285, No. 2 54-2, 01.08.2003.

Research output: Contribution to journalArticle

@article{8300ff4ca28846b4b1e48b2d0ecbd5c3,
title = "Transforming growth factor-β inhibition of proteasomal activity: A potential mechanism of growth arrest",
abstract = "Although the proteasome plays a critical role in the controlled degradation of proteins involved in cell cycle control, the direct modulation of proteasomal function by growth regulatory signaling has not yet been demonstrated. We assessed the effect of transforming growth factor (TGF)-β, a potent inhibitor of cell growth, on proteasomal function. TGF-β selectively decreased hydrolysis of the proteasomal substrate Cbz-Leu-Leu-Leu-7-amido-4-methyl-coumarin (z-LLL-AMC) in a concentration-dependent manner but did not inhibit hydrolysis of other substrates Suc-Leu-Leu-Val-Tyr-AMC (suc-LLVY-AMC) or Cbz-Leu-Leu-Glu-AMC (z-LLE-AMC). An increase in intracellular oxidative injury occurred during incubation with TGF-β. Furthermore, in vitro hydrolysis of z-LLL-AMC, but not suc-LLVY-AMC, was decreased by hydrogen peroxide. TGF-β did not increase cellular expression of heat shock protein (HSP)90, a potent inhibitor of z-LLL-AMC hydrolysis in vitro. The physiological relevance of TGF-β inhibition of proteasomal activity was studied by assessing the role of z-LLL-AMC hydrolysis on cyclin-dependent kinase inhibitor expression and cell growth. TGF-β increased expression of p27KIP1 but did not alter expression of p21WAF1 or p16INK4A. The peptide aldehyde Cbz-Leu-Leu-leucinal (LLL-CHO or MG132) potently inhibited z-LLL-AMC hydrolysis in cell extracts as well as increasing p27KIP1 and decreasing cell proliferation. Thus growth inhibition by TGF-β decreases a specific proteasomal activity via an HSP90-independent mechanism that may involve oxidative inactivation or modulation of proteasomal subunit composition and results in altered cellular expression of key cell cycle regulatory proteins such as p27KIP1.",
keywords = "Cell cycle regulation, Cytokine, Heat shock protein, Oxidative stress",
author = "Laura Tadlock and Yoko Yamagiwa and James Hawker and Carla Marienfeld and Patel, {Tushar C}",
year = "2003",
month = "8",
day = "1",
language = "English (US)",
volume = "285",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
publisher = "American Physiological Society",
number = "2 54-2",

}

TY - JOUR

T1 - Transforming growth factor-β inhibition of proteasomal activity

T2 - A potential mechanism of growth arrest

AU - Tadlock, Laura

AU - Yamagiwa, Yoko

AU - Hawker, James

AU - Marienfeld, Carla

AU - Patel, Tushar C

PY - 2003/8/1

Y1 - 2003/8/1

N2 - Although the proteasome plays a critical role in the controlled degradation of proteins involved in cell cycle control, the direct modulation of proteasomal function by growth regulatory signaling has not yet been demonstrated. We assessed the effect of transforming growth factor (TGF)-β, a potent inhibitor of cell growth, on proteasomal function. TGF-β selectively decreased hydrolysis of the proteasomal substrate Cbz-Leu-Leu-Leu-7-amido-4-methyl-coumarin (z-LLL-AMC) in a concentration-dependent manner but did not inhibit hydrolysis of other substrates Suc-Leu-Leu-Val-Tyr-AMC (suc-LLVY-AMC) or Cbz-Leu-Leu-Glu-AMC (z-LLE-AMC). An increase in intracellular oxidative injury occurred during incubation with TGF-β. Furthermore, in vitro hydrolysis of z-LLL-AMC, but not suc-LLVY-AMC, was decreased by hydrogen peroxide. TGF-β did not increase cellular expression of heat shock protein (HSP)90, a potent inhibitor of z-LLL-AMC hydrolysis in vitro. The physiological relevance of TGF-β inhibition of proteasomal activity was studied by assessing the role of z-LLL-AMC hydrolysis on cyclin-dependent kinase inhibitor expression and cell growth. TGF-β increased expression of p27KIP1 but did not alter expression of p21WAF1 or p16INK4A. The peptide aldehyde Cbz-Leu-Leu-leucinal (LLL-CHO or MG132) potently inhibited z-LLL-AMC hydrolysis in cell extracts as well as increasing p27KIP1 and decreasing cell proliferation. Thus growth inhibition by TGF-β decreases a specific proteasomal activity via an HSP90-independent mechanism that may involve oxidative inactivation or modulation of proteasomal subunit composition and results in altered cellular expression of key cell cycle regulatory proteins such as p27KIP1.

AB - Although the proteasome plays a critical role in the controlled degradation of proteins involved in cell cycle control, the direct modulation of proteasomal function by growth regulatory signaling has not yet been demonstrated. We assessed the effect of transforming growth factor (TGF)-β, a potent inhibitor of cell growth, on proteasomal function. TGF-β selectively decreased hydrolysis of the proteasomal substrate Cbz-Leu-Leu-Leu-7-amido-4-methyl-coumarin (z-LLL-AMC) in a concentration-dependent manner but did not inhibit hydrolysis of other substrates Suc-Leu-Leu-Val-Tyr-AMC (suc-LLVY-AMC) or Cbz-Leu-Leu-Glu-AMC (z-LLE-AMC). An increase in intracellular oxidative injury occurred during incubation with TGF-β. Furthermore, in vitro hydrolysis of z-LLL-AMC, but not suc-LLVY-AMC, was decreased by hydrogen peroxide. TGF-β did not increase cellular expression of heat shock protein (HSP)90, a potent inhibitor of z-LLL-AMC hydrolysis in vitro. The physiological relevance of TGF-β inhibition of proteasomal activity was studied by assessing the role of z-LLL-AMC hydrolysis on cyclin-dependent kinase inhibitor expression and cell growth. TGF-β increased expression of p27KIP1 but did not alter expression of p21WAF1 or p16INK4A. The peptide aldehyde Cbz-Leu-Leu-leucinal (LLL-CHO or MG132) potently inhibited z-LLL-AMC hydrolysis in cell extracts as well as increasing p27KIP1 and decreasing cell proliferation. Thus growth inhibition by TGF-β decreases a specific proteasomal activity via an HSP90-independent mechanism that may involve oxidative inactivation or modulation of proteasomal subunit composition and results in altered cellular expression of key cell cycle regulatory proteins such as p27KIP1.

KW - Cell cycle regulation

KW - Cytokine

KW - Heat shock protein

KW - Oxidative stress

UR - http://www.scopus.com/inward/record.url?scp=0042744088&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0042744088&partnerID=8YFLogxK

M3 - Article

C2 - 12646415

AN - SCOPUS:0042744088

VL - 285

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

SN - 1931-857X

IS - 2 54-2

ER -