[Abnormal shift of connexin 43 gap-junction protein induced by 50 Hz electromagnetic fields in Chinese hamster lung cells].

Abstract

OBJECTIVE: To study the effects of extremely low frequency magnetic fields(ELF MF) on the amount and localization of connexin 43(Cx43) gap-junction protein in the Chinese hamster lung(CHL) cells, and to explore the mechanism of ELF MF suppression on gap-junctional intercellular communication(GJIC). METHODS: The cells were irradiated for 24 h with 50 Hz sinusoidal magnetic field at 0.8 mT without or with 12-O-tetrade-canoylphorbol-3-acetate(TPA), 5 ng/ml for 1 h. The localization of Cx43 proteins were performed by indirect immunofluorescence histochemical analysis and detected by confocal microscopy. The second experiment was conducted to examine the quantity of Cx43 proteins level in nuclei or cytoplasm and detected by Western blotting analysis. RESULTS: The cells exposed to TPA for 1 h displayed less bright labelled spots in the regions of intercellular junction than the normal cells. Most of Cx43 labelled spots occurred in the cytoplasm and aggregated near the nuclei. At the same time, the amount of Cx43 protein in cytoplasm were increased[(2.03 +/- 0.89) in ELF group, (2.43 +/- 0.82) in TPA group] as compared to normal control(1.04 +/- 0.17) (P < 0.01). CONCLUSION: Inhibition on GJIC function by ELF MF alone or combined with TPA may be related with the shift of Cx43 from the regions of intercellular junction to the cytoplasm.

AI evidence extraction

Main findings

After exposure conditions described, Cx43 labeling was reduced at intercellular junction regions and appeared more in the cytoplasm with aggregation near nuclei. Cytoplasmic Cx43 protein amount was increased in the ELF group (2.03 ± 0.89) and TPA group (2.43 ± 0.82) compared with normal control (1.04 ± 0.17) (P < 0.01). The authors conclude that ELF MF alone or combined with TPA may inhibit GJIC via a shift of Cx43 from junctional regions to the cytoplasm.

Outcomes measured

• Connexin 43 (Cx43) localization (intercellular junction vs cytoplasm/nuclear region)
• Cx43 protein amount in cytoplasm (Western blot)
• Gap-junctional intercellular communication (GJIC) inhibition (mechanistic inference)

Limitations

• In vitro cell model; findings may not generalize to humans or in vivo conditions
• Sample size and replication details not reported in the abstract
• Exposure metric reported as magnetic flux density (0.8 mT); no dosimetry beyond this is provided
• Co-exposure with TPA complicates attribution of effects specifically to ELF MF

Suggested hubs

• occupational-exposure (0.55)
  Published in an industrial hygiene/occupational diseases journal and studies ELF magnetic field exposure relevant to workplace settings.

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "ELF",
        "source": null,
        "frequency_mhz": 5.00000000000000023960868011929647991564706899225711822509765625e-5,
        "sar_wkg": null,
        "duration": "24 h (ELF MF); TPA 5 ng/ml for 1 h (co-exposure condition)"
    },
    "population": "Chinese hamster lung (CHL) cells",
    "sample_size": null,
    "outcomes": [
        "Connexin 43 (Cx43) localization (intercellular junction vs cytoplasm/nuclear region)",
        "Cx43 protein amount in cytoplasm (Western blot)",
        "Gap-junctional intercellular communication (GJIC) inhibition (mechanistic inference)"
    ],
    "main_findings": "After exposure conditions described, Cx43 labeling was reduced at intercellular junction regions and appeared more in the cytoplasm with aggregation near nuclei. Cytoplasmic Cx43 protein amount was increased in the ELF group (2.03 ± 0.89) and TPA group (2.43 ± 0.82) compared with normal control (1.04 ± 0.17) (P < 0.01). The authors conclude that ELF MF alone or combined with TPA may inhibit GJIC via a shift of Cx43 from junctional regions to the cytoplasm.",
    "effect_direction": "harm",
    "limitations": [
        "In vitro cell model; findings may not generalize to humans or in vivo conditions",
        "Sample size and replication details not reported in the abstract",
        "Exposure metric reported as magnetic flux density (0.8 mT); no dosimetry beyond this is provided",
        "Co-exposure with TPA complicates attribution of effects specifically to ELF MF"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "extremely low frequency magnetic fields",
        "ELF MF",
        "50 Hz",
        "0.8 mT",
        "connexin 43",
        "Cx43",
        "gap junction",
        "GJIC",
        "Chinese hamster lung cells",
        "TPA",
        "immunofluorescence",
        "confocal microscopy",
        "Western blot"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.5500000000000000444089209850062616169452667236328125,
            "reason": "Published in an industrial hygiene/occupational diseases journal and studies ELF magnetic field exposure relevant to workplace settings."
        }
    ]
}

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