Differential Response of Heat-Shock-Induced p38 MAPK and JNK Activity in PC12 Mutant and PC12 Parental Cells for Differentiation and Apoptosis

Among the 3 mitogen-activated protein kinases -- ERK, p38 MAPK and JNK -- JNK has been suggested to participate in apoptosis, whereas p38 MAPK is thought to be part of the differentiation response. There are many common inducers of JNK and p38 MAPK, but the mechanisms underlying the differential response to apoptosis and differentiation are poorly understood. We found that heatshock activated p38 MAPK at 3min after exposure to a temperature of 44 in stress-hypersensitive PC12m3 mutant cells, while it activated JNK at 20min after the same heat treatment. However, heat shock activated p38 MAPK 5min after heat treatment and JNK 10min after heat treatment in PC12 parental cells. The extent of phosphorylation of p38 MAPK induced by heat shock in PC12m3 cells was significantly greater than that in PC12 parental cells, and a high level of heat-shock-induced neurite outgrowth was observed only in PC12m3 cells. On the other hand, heat-shock-induced JNK activation appeared more quickly and apoptosis started earlier in PC12 parental cells. These findings indicate that short stress induces p38 MAPK and longer stress induces JNK, and that the response of these kinases to heat shock differs depending on cell type.</p

経済学の成績に対する数学学習の効果 : コントロール関数アプローチによる推定と予備検定

要旨あり原著論

Heat Shock-Induced Three-Dimensional-Like Proliferation of Normal Human Fibroblasts Mediated by Pressed Silk

The aim of this study was to determine the optimal heat treatment conditions for enhancement of pressed silk-mediated 3D-like proliferation of normal human dermal fibroblasts, as well as to determine the responses to heat shock of cells and intracellular signaling pathways. The beginning of 3D-like pattern formation of cells was observed in the second week after the start of the experiment. The mean rates of beginning of 3D-like pattern formation by cells heat-treated at 40 ºC and 43 ºC for 10 min were significantly higher (3.2- and 8.6-fold, respectively) than that of untreated cells. We found that apoptosis had occurred in 7.5% and 50.0% of the cells at one week after heat treatment for 10 min at 43 ºC and 45 ºC, respectively. Western blot analysis demonstrated that phosphorylation of p38 MAPK and that of Hsp27 were markedly increased by heat treatment at 43 ºC for 10 min. The results of an experiment using a p38 MAPK inhibitor and Hsp27 inhibitor suggest that activation of p38 MAPK by heat shock is associated with 3D-like cell proliferation and that Hsp27 contributes to the inhibition of apoptosis. The results of this study should be useful for further studies aimed at elucidation of the physiologic mechanisms underlying thermotherapy

細胞の三次元様増殖を指標とした温熱療法の最適条件に関する研究

本研究の目的は、三次元様増殖に温熱刺激が効果的に働く最適量と最小量を示すことであった。C3H10T1/2マウス線維芽細胞とハイドロキシアパタイトを混合し、設定温度が40℃・41.5℃・43℃・44℃・45℃、処理時間は2分間・10分間・15分間・20分間・30分間・45分間・60分間・90分間・180分間・360分間の温熱刺激を与えて10週間培養することにより三次元様増殖形成に必要な最小と最適な温熱量を調べた。その結果、三次元様増殖形成に必要な最小の温熱量は43℃2分間、また最適な温熱量は43℃10分間であった。43℃2分間は非処理対照の1.7倍、43℃10分間では3.7倍と非常に高い形成率となり、それぞれ有意差がみられた(p<0.05)。また、40℃で90分間・180分間と41.5℃15分間および44℃10分間も対照群に比べ高い形成率であった。43℃10分間の温熱処理では1週間後に約80%がアポトーシスになっていた。ウエスタンブロット分析により43℃10分間の温熱処理によってp38 MAPK の活性化が明らかであった。これらの結果から、温熱刺激による三次元様増殖はp38 MAPK の経路を介していることが判明した。本研究結果は最適な温熱量を提示するものとして温熱療法の基礎となり、温熱療法の効果を細胞生物学的に示すための重要な知見になると考えられる