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Hyperphosphorylation of microfilament-associated proteins is involved in microcystin-LR-induced toxicity in HL7702

Jing Zeng1, Wei-Wei Tu1, Lissy Lazar1

  • 1Department of Preventive Medicine, School of Medicine, Ningbo University, Ningbo, 315211, China.

Environmental Toxicology
|March 29, 2014
PubMed

Insights

Microcystin-LR (MC-LR) disrupts liver cell actin filaments by increasing protein phosphorylation, not altering protein levels. This cytoskeletal damage is mediated by the P38 and ERK1/2 pathways.

Area of Science:

  • Toxicology
  • Cell Biology
  • Biochemistry

Background:

  • Microcystin-LR (MC-LR) is a known hepatotoxin.
  • MC-LR's effects on cytoskeletal reorganization, particularly actin filaments, are not fully understood.
  • Investigating the molecular mechanisms of MC-LR-induced liver cell damage is crucial.

Purpose of the Study:

  • To determine if MC-LR disrupts actin filaments in normal human liver cells (HL7702).
  • To analyze the impact of MC-LR on the transcription, translation, and phosphorylation of key microfilament-associated proteins.
  • To elucidate the underlying molecular mechanisms of MC-LR-induced cytoskeletal disruption.

Main Methods:

  • Treatment of HL7702 cells with MC-LR.
  • Assessment of actin filament organization and depolymerization.
  • Measurement of mRNA and protein expression levels of ezrin, VASP, Arp2/3, and cofilin.
  • Analysis of protein phosphorylation status and involvement of MAPK pathways (P38, ERK1/2).

Main Results:

  • MC-LR treatment led to loss of actin filament organization and increased depolymerization in HL7702 cells.
  • mRNA and protein levels of ezrin, VASP, Arp2/3, and cofilin remained unchanged.
  • Phosphorylation levels of ezrin and VASP significantly increased upon MC-LR exposure.
  • The P38 and ERK1/2 mitogen-activated protein kinase pathways were implicated in the hyperphosphorylation of these proteins.

Conclusions:

  • MC-LR induces disruption of actin filaments in human liver cells (HL7702).
  • This disruption is primarily due to MC-LR-induced hyperphosphorylation of microfilament-associated proteins like ezrin and VASP.
  • Activation of the MAPK pathways (P38/ERK1/2) is central to the observed cellular damage.
Keywords:
actinhyperphosphorylationmicrocystin-LRmicrofilamentmitogen-activated protein kinase

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