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Crosstalk between Smad2/3 and specific isoforms of ERK in TGF-β1-induced TIMP-3 expression in rat chondrocytes

Yanhui Zhu1, Jianhua Gu1, Tong Zhu1

  • 1Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.

Journal of Cellular and Molecular Medicine
|February 24, 2017
PubMed

Insights

Extracellular signal-regulated kinases (ERK1/2) play distinct roles in chondrocyte response to transforming growth factor-β1 (TGF-β1). ERK1, not ERK2, regulates TGF-β1-induced tissue inhibitor of metalloproteinases-3 (TIMP-3) expression and matrix production.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Transforming growth factor-β1 (TGF-β1) is crucial for chondrocyte function and extracellular matrix (ECM) homeostasis.
  • Dysregulation of TGF-β1 signaling contributes to cartilage degradation in osteoarthritis.
  • Tissue inhibitor of metalloproteinases-3 (TIMP-3) is an important regulator of matrix metalloproteinases (MMPs) and ECM integrity.

Purpose of the Study:

  • To elucidate the specific roles of ERK1 and ERK2 in TGF-β1-induced TIMP-3 expression in rat chondrocytes.
  • To investigate the molecular mechanism of ERK1/2 regulation of TGF-β1 signaling, focusing on crosstalk with Smad2/3.
  • To determine the impact of ERK1 and ERK2 on chondrocyte matrix production.

Main Methods:

  • Rat chondrocytes were treated with TGF-β1 and infected with lentiviral vectors expressing ERK1 or ERK2 siRNA.
  • TIMP-3 expression was quantified using real-time PCR and Western blotting.
  • Levels of phosphorylated Smad3 (p-Smad3), nuclear p-Smad3, Smad2/3, phosphorylated ERK1/2 (p-ERK1/2), and ERK1/2 were assessed.
  • Expression of aggrecan, type II collagen, and matrix intensity were examined.

Main Results:

  • Knockdown of ERK1 significantly inhibited TGF-β1-induced TIMP-3 expression and reduced p-Smad3 levels.
  • Knockdown of ERK2 did not affect TGF-β1-induced TIMP-3 expression or p-Smad3 levels.
  • ERK1 knockdown, but not ERK2 knockdown, suppressed aggrecan, type II collagen expression, and matrix intensity.
  • ERK1, unlike ERK2, was found to regulate TGF-β/Smad signaling.

Conclusions:

  • ERK1 and ERK2 exhibit differential roles in TGF-β1-mediated responses in rat chondrocytes.
  • ERK1, but not ERK2, plays a critical role in regulating TGF-β1-induced TIMP-3 expression via the TGF-β/Smad signaling pathway.
  • ERK1 is a key mediator of TGF-β1's effects on chondrocyte matrix synthesis and homeostasis.
Keywords:
CrosstalkERK isoformsOsteoarthritisSmad2/3TGF-β1TIMP3

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