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 3 min after exposure to a temperature of 44 degrees C in stress-hypersensitive PC12m3 mutant cells, while it activated JNK at 20 min after the same heat treatment. However, heatshock activated p38 MAPK 5min after heat treatment and JNK 10 min 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.

C-SH2 point mutation converts p85ß regulatory subunit of phosphoinositide 3-kinase to an anti-aging gene.

Insulin interacts with the insulin receptor, and the activated receptor promotes activity of the phosphoinositide-3 kinase (PI3K) enzyme. A decrease in insulin or insulin-like growth factor 1 (IGF-1) signaling increases the lifespan in mammalian species. We found that a point mutation in the C-SH2 domain of the p85ß regulatory subunit of PI3K results in a prolonged lifespan. In p85ß mutant cells, nerve growth factor (NGF) activates the longevity protein FOXO, and the mutant p85ß gene produces strong resistance to oxidative stress, which contributes to aging. The p85ß gene mutation causes increased serum insulin and low blood glucose in p85ß mutant transgenic mice. Our results indicate that the p85ß mutant allele alters the activity of downstream targets of PI3K by NGF and platelet-derived growth factor (PDGF) but not by insulin. We report that a point mutation in the C-SH2 domain of p85ß transforms p85ß into a novel anti-aging gene by abnormally regulating PI3K.

Artepillin C derived from propolis induces neurite outgrowth in PC12m3 cells via ERK and p38 MAPK pathways.

We investigated whether artepillin C, a major component of Brazilian propolis, acts as a neurotrophic-like factor in rat PC12m3 cells, in which nerve growth factor (NGF)-induced neurite outgrowth is impaired. When cultures of PC12m3 cells were treated with artepillin C at a concentration of 20 microM, the frequency of neurite outgrowth induced by artepillin C was approximately 7-fold greater than that induced by NGF alone. Artepillin C induced-neurite outgrowth of PC12m3 cells was inhibited by the ERK inhibitor U0126 and by the p38 MAPK inhibitor SB203580. Although artepillin C-induced p38 MAPK activity was detected in PC12m3 cells, phosphorylation of ERK induced by artepillin C was not observed. On the other hand, artepillin C caused rapid activation of ERK and the time course of the activation was similar to that induced by NGF treatment in PC12 parental cells. However, NGF-induced neurite outgrowth was inhibited by artepillin C treatment. Interestingly, inhibition of ERK by U0126 completely prevented artepillin C-induced p38 MAPK phosphorylation of PC12m3 cells. These findings suggest that artepillin C-induced activation of p38 MAPK through the ERK signaling pathway is responsible for the neurite outgrowth of PC12m3 cells.

Microwave irradiation induces neurite outgrowth in PC12m3 cells via the p38 mitogen-activated protein kinase pathway.

The increasing use of mobile phone communication has raised concerns about possible health hazard effects of microwave irradiation. We investigated damage and differentiation caused by microwave irradiation on drug-hypersensitive PC12 cell line (PC12m3). These cells showed enhancement of neurite outgrowth to various stimulants. The frequency of neurite outgrowth induced by 2.45 GHz (200 W) of microwave irradiation was approximately 10-fold greater than that of non-irradiated control cells. Incubation of PC12m3 cells with SB203580, a specific inhibitor of p38 MAPK, resulted in marked inhibition of the microwave radiation-induced neurite outgrowth. Also, activation of the transcription factor CREB induced by microwave irradiation was inhibited by SB203580. Heat shock treatment at 45 degrees C had a strong toxic effect on PC12m3 cells, whereas microwave treatment had no toxic effect on PC12m3 cells. These findings indicate that p38 MAPK is responsible for the survival of PC12m3 cells and might induce neurite outgrowth via a CREB signaling pathway when subjected to microwave irradiation.

Heat-shock-induced three-dimensional-like proliferation of mouse fibroblasts mediated by hydroxyapatite.

The aim of the present study was to determine both the minimal and the optimal conditions under which heat treatment is effective for enhancing 3D (three-dimensional)-like cell proliferation. C3H10T1/2 mouse fibroblasts were cultured with hydroxyapatite granules for 10 weeks after heat treatment at 40, 41.5, 43, 44 or 45 degrees C for 2, 10, 15, 20, 30, 45, 60, 90, 180 and 360 min. Then minimal and optimal conditions of temperature and duration of heat treatment for induction of 3D-like proliferation of cells were determined. The minimal conditions of heat treatment to induce 3D-like proliferation were 43 degrees C for 2 min and the optimal conditions were 43 degrees C for 10 min. The mean rates of formation of 3D-like proliferation patterns by cells heat-treated at 43 degrees C for 2 and 10 min were significantly higher (1.7- and 3.7-fold respectively) than that by untreated cells (P<0.05). We also observed significantly greater effects of heat treatment on 3D-like proliferation at 40 degrees C for 90 or 180 min and at 41.5 degrees C for 15 min and 44 degrees C for 10 min. We found that apoptosis had occurred in 7.5 and 87.0% of the cells at 1 week after heat treatment at 43 degrees C for 10 min and 30 min respectively. Western-blot analysis demonstrated that phosphorylation of p38 MAPK (mitogen-activated protein kinase) was markedly increased by heat treatment at 43 degrees C for 10 min. These findings suggest that activation of p38 MAPK by heat shock is associated with 3D-like cell proliferation. The results of the present study should be useful for further studies aimed at elucidation of the physiological mechanisms underlying thermotherapy and hyperthermia.

Intracranial self-stimulation-reward induces neurite extension in PC12m3 cells and activation of the p38 MAPK pathway.

Factors that trigger emotional expression may be divided into two patterns according to the type of motivation, acquiring reward (pleasure) and avoiding aversion (punishment). Repeated exposure to certain external stimuli accompanied by aberrant motivation may produce psychiatric diseases such as bipolar disorder and addiction via dysregulation of the central nervous system. However, neurobiological underpinnings of such diseases have not been clarified, especially at the neuronal level. In the present study, plasma from rats undergoing intracranial self-stimulation (ICSS) produced neurite outgrowth in PC12-variant cells (PC12m3). Stimulated PC12m3 cells also exhibited heightened activity of the p38 MAPK pathway. These findings indicate that reward states lead to not only morphological changes but also increases in p38 MAPK activity at the neuronal level in the central nervous system.

Enhancement of hydroxyapatite-mediated three-dimensional-like proliferation of mouse fibroblasts by heat treatment: effects of heat shock-induced p38 MAPK pathway.

Regulation of the biocompatibility of compositional hydroxyapatite (HA) with cells is affected by various environmental factors. The aim of this study was to determine whether the p38 mitogen-activated protein kinase (MAPK) pathway has a key role in enhancement of HA-mediated three-dimensional (3D)-like proliferation of mouse fibroblasts after heat treatment. C3H10T1/2 mouse fibroblasts were cultured with HA granules for 10 weeks after heat treatment at 44 degrees C for 5, 10, 20, and 30 min. The mean rate of formation of 3D-like proliferation patterns by cells heat treated for 20 min was only 2.1-fold higher than that by untreated cells, but the mean rates of formation of 3D-like proliferation patterns by cells heat treated for 5 and 10 min were significantly higher (3.7- and 3.3-fold higher, respectively) than that by untreated cells (p < 0.01). Western blot analysis demonstrated that phosphorylation of p38 MAPK was markedly increased by heat treatment at 44 degrees C for 5 and 10 min. In addition, the activation of heat shock-induced p38 MAPK was markedly reduced by treatment at 44 degrees C for 30 min. We concluded that 3D-like proliferation of heat-treated cells was induced by activation of p38 MAPK. The results of this study should be useful for further studies aimed at elucidation of regulation of the biocompatibility of compositional HA with cells.

Heat shock induces neurite outgrowth in PC12m3 cells via the p38 mitogen-activated protein kinase pathway.

We investigated the role of the p38 mitogen-activated protein kinase (MAPK) pathway in heat-shock-induced neurite outgrowth of PC12 mutant cells in which nerve growth factor (NGF)-induced neurite outgrowth is impaired. When cultures of the PC12 mutant (PC12m3) cells were exposed to heat stress at 44 degrees C for 10 min, activity of p38 MAPK increased and neurite outgrowth was greatly enhanced. The neurite extension was inhibited by the p38 MAPK inhibitor BS203580. Longer heat treatment of PC12m3 cells provoked cell death, which was enhanced by SB203580. These findings suggest that heat-induced activation of p38 MAPK is responsible for the neurite outgrowth and survival of PC12m3 cells.

Effect of a steam foot spa on geriatric inpatients with cognitive impairment: a pilot study.

PURPOSE: To investigate whether a steam foot spa improves cognitive impairment in geriatric inpatients. METHODS: Geriatric inpatients with cognitive impairment were given a steam foot spa treatment at 42°C for 20 minutes for 2 weeks (5 days/week). Physiological indicators such as blood pressure, percutaneous oxygen saturation, pulse, tympanic temperature, and sleep time and efficiency were assessed. Cognitive function and behavioral and psychological symptoms of dementia were assessed using the Mini-Mental State Examination, Dementia Mood Assessment Scale, and Dementia Behavior Disturbance scale. RESULTS: Significant decreases in systolic (P < 0.01) and diastolic blood pressure (P < 0.05) along with a significant increase in tympanic temperature (P < 0.01) were observed after the steam foot spas. A significant improvement was seen in the Mini-Mental State Examination score (P < 0.01) and the overall dementia severity items in Dementia Mood Assessment Scale (P < 0.05). LIMITATIONS: Japanese people are very fond of foot baths. However, it is difficult to understand why inpatients cannot receive steam foot baths. In this study, a control group was not used. Raters and enforcers were not blinded. CONCLUSION: The results of this pilot study suggest that steam foot spas mitigate cognitive impairment in geriatric inpatients.

Immunosuppressant FK506 induces sustained activation of MAP kinase and promotes neurite outgrowth in PC12 mutant cells incapable of differentiating.

During the continuous culturing of neural PC12 cells, a drug hypersensitive PC12 mutant cell line (PC12m3) was obtained, which demonstrated high neurite outgrowth when stimulated by various drugs. When the immunosuppressant drug FK506 and nerve growth factor (NGF) were introduced to the PC12m3 cells, the frequency of neurite outgrowth increased approximately 40-fold for NGF alone. However, the effect of FK506 on neuritogenesis in PC12 parental and drug insensitive PC12m1 mutant cells was much lower than in PC12m3 cells. The sustained activation of mitogen-activated protein (MAP) kinase plays an important role in neurite outgrowth of PC12 cells. Interestingly, the drug hypersensitive PC12m3 cells exhibited the sustained activation of MAP kinase with FK506 in comparison to low or no activities in PC12 parental or drug insensitive PC12m1 cells. These results indicate that PC12m3 cells have a novel FK506-induced MAP kinase pathway for neuritogenesis.