[Effects of power-frequency magnetic fields exposure on phosphorylation and enzymatic activity of stress-activated protein kinase and its upstream kinase].

Zhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational diseases · 2002 · Mixed · Low evidence

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MixedLow evidencePaper 3804

Exposure to 50 Hz magnetic fields at 0.4 mT or 0.8 mT increased SAPK phosphorylation over time, peaking at 15 min (20% and 17% increases, respectively). SAPK enzymatic activity at 15 min was increased to 2.9±0.4 and 2.1±0.9 times control for 0.4 mT and 0.8 mT…

Study snapshot

PublicationZhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational diseases · 2002

Study typein_vitro

Reported directionMixed

Evidence ratingLow

Abstract

OBJECTIVE: To study the effects of 50 Hz power-frequency magnetic fields on signal transduction pathway of stress-activated protein kinase(SAPK), and explore the cellular signal transduction mechanism of the biological effects induced by power-frequency magnetic fields. METHODS: Chinese hamster lung(CHL) cell line was exposed to power-frequency magnetic fields with two intensities for different exposure durations. The cytoplasmic protein was extracted and the phosphorylated portion of SAPK and SEK1/MKK4 was measured with Western blotting analysis. The SAPK enzymatic activity was measured by the solid-phase kinase assay in cells exposed to power-frequency magnetic fields for 15 min. RESULTS: Both 0.4 mT and 0.8 mT power-frequency magnetic fields could enhance the phosphorylation of SAPK in a time-relative course manner, and reached the maximum extent at 15 min, with an increase of 20% and 17% respectively. The solid-phase kinase assay showed that the enzymatic activities of SAPK were also increased, which were 2.9 +/- 0.4 and 2.1 +/- 0.9 times of control respectively. However, the duration of SAPK phosphorylation induced by 0.8 mT was longer than that of 0.4 mT, while the duration and extent of SAPK dephosphorylation was remarkably shorter than that of 0.4 mT. The power-frequency magnetic fields under equal conditions could not phosphorylate(activate) the SEK1/MKK4. CONCLUSION: Power-frequency magnetic fields could activate the SAPK, but not SEK1/MKK4. It is suggested that power-frequency magnetic fields may activate SAPK signal transduction pathway through a kinase other than SEK1/MKK4. The activation mechanism of SAPK of power-frequency magnetic fields needs to be identified in more detail.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionmixed

PopulationChinese hamster lung (CHL) cell line

Sample sizeNot supplied

ExposureELF · 0.05 MHz · 15 min (kinase activity assay); phosphorylation assessed over time with different exposure durations

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Outcomes measured

SAPK phosphorylation (Western blot)
SEK1/MKK4 phosphorylation (Western blot)
SAPK enzymatic activity (solid-phase kinase assay)

Limitations

In vitro cell-line study; findings may not generalize to humans
Sample size and replication details not reported in abstract
Only two field intensities tested (0.4 mT, 0.8 mT)
Limited pathway coverage (SEK1/MKK4 assessed; other upstream kinases not identified)
Short exposure durations emphasized (peak at 15 min)

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": "15 min (kinase activity assay); phosphorylation assessed over time with different exposure durations"
  },
  "population": "Chinese hamster lung (CHL) cell line",
  "sample_size": null,
  "outcomes": [
    "SAPK phosphorylation (Western blot)",
    "SEK1/MKK4 phosphorylation (Western blot)",
    "SAPK enzymatic activity (solid-phase kinase assay)"
  ],
  "main_findings": "Exposure to 50 Hz magnetic fields at 0.4 mT or 0.8 mT increased SAPK phosphorylation over time, peaking at 15 min (20% and 17% increases, respectively). SAPK enzymatic activity at 15 min was increased to 2.9±0.4 and 2.1±0.9 times control for 0.4 mT and 0.8 mT, respectively. Under the same conditions, SEK1/MKK4 was not phosphorylated/activated.",
  "effect_direction": "mixed",
  "limitations": [
    "In vitro cell-line study; findings may not generalize to humans",
    "Sample size and replication details not reported in abstract",
    "Only two field intensities tested (0.4 mT, 0.8 mT)",
    "Limited pathway coverage (SEK1/MKK4 assessed; other upstream kinases not identified)",
    "Short exposure durations emphasized (peak at 15 min)"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "50 Hz",
    "power-frequency magnetic field",
    "ELF magnetic fields",
    "Chinese hamster lung cells",
    "CHL",
    "SAPK",
    "JNK",
    "SEK1",
    "MKK4",
    "phosphorylation",
    "kinase activity",
    "signal transduction"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.35,
      "reason": "Published in an industrial hygiene/occupational diseases journal and studies power-frequency magnetic fields, relevant to occupational ELF exposure contexts."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: Not supplied
PubMed: 14694647

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