研究のタイプ: 医学／生物学の研究 (experimental study)

[ELF-EMFへ短期ばく露されたヒトケラチノサイトにおけるPI3K/AktおよびERKシグナリングによるmTORの活性化] med./bio.

mTOR Activation by PI3K/Akt and ERK Signaling in Short ELF-EMF Exposed Human Keratinocytes

著者: Patruno A, Pesce M, Grilli A, Speranza L, Franceschelli S, De Lutiis MA, Vianale G, Costantini E, Amerio P, Muraro R, Felaco M, Reale M
掲載誌: PLoS One 2015; 10 (10): e0139644
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この研究は、ヒト表皮角化細胞株（HaCaT細胞）の増殖に対する低周波磁界（ELF-EMF：50Hz、1mT）の影響とそれに関与する分子メカニズムを調べた。細胞増殖および生存率をフローサイトメータスキャン（FACS）解析とブロモデオキシウリジン（BrdU）アッセイでモニタし、マイクロアレイ法での遺伝発現プロファイルを定量的RT-PCRで確認した。mTOR、 Akt、MAPKsの発現をウェスタンブロット分析した。その結果、HaCaT細胞においては、ELF-EMFの短期ばく露により細胞増殖および細胞周期に関与する遺伝子発現のパターンが変化した；ELF-EMFの分子レベルの主なターゲットはmTOR活性化であった、と報告している。

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研究目的（著者による）

The effects of exposure of human keratinocytes to a 50 Hz magnetic field on cell proliferation and the underlying molecular mechanisms of action should be investigated.

詳細情報

Previous studies indicated that magnetic field exposure can increase keratinocyte proliferation (Vianale et al. 2008, Patruno et al. 2010) and can have positive effects on wound healing (Stiller et al. 1992, Matic et al. 2009).
Cells were divided into two groups: exposure and control group. Cells were exposed or not exposed for 30 minutes, 1 h, 3 h or 24 hours. All results were obtained from at least three independent experiments.
mTOR (mechanistic target of rapamycin) is an important key enzyme for growth, proliferation and survival of cells, which is involved in several signal pathways.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 50 Hz
ばく露時間: continuous for up to 24 hours

ばく露1

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous for up to 24 hours
ばく露装置
ばく露の発生源／構造
チャンバの詳細 culture plates in incubator
ばく露装置の詳細 a 160-turn solenoid coil (22 cm length, 6 cm radius, copper wire diameter of 1.25x10-5 cm, current flow of 1.2 A) generated the MF in the incubator; culture plates were placed at the center of the solenoid with 98% uniformity; cells were incubated at 37°C in a humidified atmosphere and 5% CO2; max. temperature difference in cell cultures between exposure and control group was 0.1°C
Additional information an identical incubator was used for the control group
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 1 mT effective value 測定値 - -

Reference articles

  • Patruno A et al. (2011): [ヒトのHaCaTおよびTHP-1細胞株におけるカタラーゼ、シトクロムP450および誘導性一酸化窒素合成酵素に対する超低周波電磁界の影響に関する動態学的研究]
  • Vianale G et al. (2008): [超低周波電磁界はヒトケラチノサイト細胞の増殖促進および炎症促進性ケモカイン産生減少を引き起こす]
  • Reale M et al. (2006): [50 Hz 正弦波電磁界によるMCP-1 および iNOS の変化]

ばく露を受けた生物:

方法 影響評価項目／測定パラメータ／方法

研究対象とした生物試料:
調査の時期:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム（著者による）

Cell proliferation was significantly increased and the cell cycle distribution was significantly altered after 1 h and 24 hours of exposure compared to the control group. Addition of ERK, phosphoinositide 3-kinase or JNK inhibitors led to a significantly decreased cell proliferation in both, exposure and control group, compared to respective cell cultures without inhibitors. When cells exposed for 1 h were treated with rapamycin, they showed a significantly decreased proliferation compared to non-treated exposed cells. However, cells in the control group did not react to rapamycin.
In the microarrays, a total of 153 genes were significantly differently expressed in exposed cells compared to the control group. Pathway analysis showed an association with growth and proliferation processes for the majority of the identified genes. Key enzyme genes were selected and except for mTOR and RPS6, overexpression could be confirmed for all via RT-PCR.
However, protein expression of phosphorylated mTOR was significantly increased after 1h and 3 h of exposure compared to the control group and exposed cells with addition of rapamycin or inhibitors of ERK and phosphoinositide 3-kinase showed a significantly reduced mTOR protein expression compared to exposed cells without these additives. Moreover, exposure led to significantly increased protein expression rates of ERK, JNK and protein kinase B and to a significantly reduced expression of p38 MAPK compared to the control group.
The authors conclude that exposure of human keratinocytes to a 50 Hz magnetic field might increase cell proliferation. The molecular targets of the magnetic field seem to be the protein kinase B and ERK signaling pathways, which activate mTOR.

研究の種別:

研究助成

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