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Gingerol prevents prion protein-mediated neuronal toxicity by regulating HIF prolyl hydroxylase 2 and prion protein.

Park YG, Park SY - Int. J. Mol. Med. (2014)

Bottom Line: We used the pharmacological inhibition of PHD2 by dimethyloxalylglycine (DMOG) or deferoxamine (DFO) and the genetic inhibition of HIF-1α by HIF-1α small interfering RNA (siRNA) to block the effects of gingerol against PrP (106-126)-induced neurotoxicity.Our results demonstrated that gingerol prevented PrP (106‑126)-induced neuronal apoptosis by upregulating HIF-1α and inhibiting the catalytic activity of PHD2 under normoxic conditions.In conclusion, our results indicate that gingerol has therapeutic potential for use in the treatment or prevention of prion diseases, and its inhibitory effects on the catalytic activity of PHD2 may be of clinical benefit.

View Article: PubMed Central - PubMed

Affiliation: Biosafety Research Institute, College of Veterinary Medicine, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea.

ABSTRACT
Prion diseases are a family of progressive neurodegenerative disorders, which are fatal in the majority of cases and affect both humans and domestic animals. Prion protein (PrP) (106-126) retains the neurotoxic properties of the entire pathological PrPsc and it is generally used as a reasonable model to study the mechanisms responsible for prion diseases. In our previous studies, we demonstrated that hypoxia-inducible factor (HIF)-1α is involved in the gingerol-mediated protection of neuronal cells. HIF mediates cellular adaptations to low oxygen. Prolyl hydroxylase domain-containing protein 2 (PHD2) is an oxygen sensor that hydroxylates the HIF-α-subunit, promoting its proteasomal degradation under normoxic conditions. Thus, in the present study we wished to determine whether gingerol inhibits the catalytic activity of PHD2 and prevents HIF-1α protein proteasomal degradation, thereby preventing the occurrence of PrP (106-126)-induced neuronal apoptosis. We used the pharmacological inhibition of PHD2 by dimethyloxalylglycine (DMOG) or deferoxamine (DFO) and the genetic inhibition of HIF-1α by HIF-1α small interfering RNA (siRNA) to block the effects of gingerol against PrP (106-126)-induced neurotoxicity. Our results demonstrated that gingerol prevented PrP (106‑126)-induced neuronal apoptosis by upregulating HIF-1α and inhibiting the catalytic activity of PHD2 under normoxic conditions. Moreover, the protective effects of gingerol against PrP (106-126)-induced neuronal apoptosis were associated with the upregulation of the expression of cellular prion protein (PrPc). In conclusion, our results indicate that gingerol has therapeutic potential for use in the treatment or prevention of prion diseases, and its inhibitory effects on the catalytic activity of PHD2 may be of clinical benefit.

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Gingerol-induced expression of hypoxia-inducible factor (HIF)-1α protein is involved in the upregulation of PrPc expression in neurons. (A) ZW 13-2 and Zpl 3–4 cells were incubated with 2.5 nM gingerol for 20 h. The expression of HIF-1α and PrPc was assessed by western blot analysis. Results were normalized to those of β-actin. (B) ZW 13-2 and Zpl 3–4 cells were incubated with 100 μM PrP (106–126) for 12 h following exposure to 2.5 nM gingerol for 12 h. Bar graph indicates the average numbers (%) of Annexin V-negative cells. **P<0.01 vs. controls (untreated cells), #P<0.01 vs. PrP (106–126)-treated cells. (C) Cell viability was measured by an Annexin V assay and flow cytometry. Ging, gingerol.
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f4-ijmm-34-05-1268: Gingerol-induced expression of hypoxia-inducible factor (HIF)-1α protein is involved in the upregulation of PrPc expression in neurons. (A) ZW 13-2 and Zpl 3–4 cells were incubated with 2.5 nM gingerol for 20 h. The expression of HIF-1α and PrPc was assessed by western blot analysis. Results were normalized to those of β-actin. (B) ZW 13-2 and Zpl 3–4 cells were incubated with 100 μM PrP (106–126) for 12 h following exposure to 2.5 nM gingerol for 12 h. Bar graph indicates the average numbers (%) of Annexin V-negative cells. **P<0.01 vs. controls (untreated cells), #P<0.01 vs. PrP (106–126)-treated cells. (C) Cell viability was measured by an Annexin V assay and flow cytometry. Ging, gingerol.

Mentions: HIF-1α is involved in the regulation of prion protein expression to protect neurons (15). Moreover, it has also been suggested that the gingerol-induced expression of HIF-1α is a key factor in attenuating hypoxia-induced embryo toxicity (27). In our study, to determine whether HIF-1α is stabilized by gingerol-mediated PrPc expression, ZW 13-2 and Zpl 3–4 murine neuronal cells were incubated with 2.5 nM gingerol for 20 h. As shown in Fig. 4A, following treatment with gingerol, the expression of HIF-1α and PrPc was increased in the ZW 13-2 cells. However, PrPc protein expression was not detected in the Zpl 3–4 cells (Fig. 4A). To confirm the increase in the expression of PrPc following treatment with gingerol and that this caused a beneficial effect on the ZW 13-2 and Zpl 3–4 cells, the cells were incubated with PrP (106–126) 100 μM for 12 h following a 12-h exposure to 2.5 nM gingerol. Cell viability was measured by Annexin V assay and flow cytometry. In the ZW 13-2 murine neuronal cells, gingerol had a neuroprotective effect on the PrP (106–126)-induced neuronal apoptosis. In the Zpl 3–4 cells, however, it had no neuroprotective effects (Fig. 4B and C).


Gingerol prevents prion protein-mediated neuronal toxicity by regulating HIF prolyl hydroxylase 2 and prion protein.

Park YG, Park SY - Int. J. Mol. Med. (2014)

Gingerol-induced expression of hypoxia-inducible factor (HIF)-1α protein is involved in the upregulation of PrPc expression in neurons. (A) ZW 13-2 and Zpl 3–4 cells were incubated with 2.5 nM gingerol for 20 h. The expression of HIF-1α and PrPc was assessed by western blot analysis. Results were normalized to those of β-actin. (B) ZW 13-2 and Zpl 3–4 cells were incubated with 100 μM PrP (106–126) for 12 h following exposure to 2.5 nM gingerol for 12 h. Bar graph indicates the average numbers (%) of Annexin V-negative cells. **P<0.01 vs. controls (untreated cells), #P<0.01 vs. PrP (106–126)-treated cells. (C) Cell viability was measured by an Annexin V assay and flow cytometry. Ging, gingerol.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4199419&req=5

f4-ijmm-34-05-1268: Gingerol-induced expression of hypoxia-inducible factor (HIF)-1α protein is involved in the upregulation of PrPc expression in neurons. (A) ZW 13-2 and Zpl 3–4 cells were incubated with 2.5 nM gingerol for 20 h. The expression of HIF-1α and PrPc was assessed by western blot analysis. Results were normalized to those of β-actin. (B) ZW 13-2 and Zpl 3–4 cells were incubated with 100 μM PrP (106–126) for 12 h following exposure to 2.5 nM gingerol for 12 h. Bar graph indicates the average numbers (%) of Annexin V-negative cells. **P<0.01 vs. controls (untreated cells), #P<0.01 vs. PrP (106–126)-treated cells. (C) Cell viability was measured by an Annexin V assay and flow cytometry. Ging, gingerol.
Mentions: HIF-1α is involved in the regulation of prion protein expression to protect neurons (15). Moreover, it has also been suggested that the gingerol-induced expression of HIF-1α is a key factor in attenuating hypoxia-induced embryo toxicity (27). In our study, to determine whether HIF-1α is stabilized by gingerol-mediated PrPc expression, ZW 13-2 and Zpl 3–4 murine neuronal cells were incubated with 2.5 nM gingerol for 20 h. As shown in Fig. 4A, following treatment with gingerol, the expression of HIF-1α and PrPc was increased in the ZW 13-2 cells. However, PrPc protein expression was not detected in the Zpl 3–4 cells (Fig. 4A). To confirm the increase in the expression of PrPc following treatment with gingerol and that this caused a beneficial effect on the ZW 13-2 and Zpl 3–4 cells, the cells were incubated with PrP (106–126) 100 μM for 12 h following a 12-h exposure to 2.5 nM gingerol. Cell viability was measured by Annexin V assay and flow cytometry. In the ZW 13-2 murine neuronal cells, gingerol had a neuroprotective effect on the PrP (106–126)-induced neuronal apoptosis. In the Zpl 3–4 cells, however, it had no neuroprotective effects (Fig. 4B and C).

Bottom Line: We used the pharmacological inhibition of PHD2 by dimethyloxalylglycine (DMOG) or deferoxamine (DFO) and the genetic inhibition of HIF-1α by HIF-1α small interfering RNA (siRNA) to block the effects of gingerol against PrP (106-126)-induced neurotoxicity.Our results demonstrated that gingerol prevented PrP (106‑126)-induced neuronal apoptosis by upregulating HIF-1α and inhibiting the catalytic activity of PHD2 under normoxic conditions.In conclusion, our results indicate that gingerol has therapeutic potential for use in the treatment or prevention of prion diseases, and its inhibitory effects on the catalytic activity of PHD2 may be of clinical benefit.

View Article: PubMed Central - PubMed

Affiliation: Biosafety Research Institute, College of Veterinary Medicine, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea.

ABSTRACT
Prion diseases are a family of progressive neurodegenerative disorders, which are fatal in the majority of cases and affect both humans and domestic animals. Prion protein (PrP) (106-126) retains the neurotoxic properties of the entire pathological PrPsc and it is generally used as a reasonable model to study the mechanisms responsible for prion diseases. In our previous studies, we demonstrated that hypoxia-inducible factor (HIF)-1α is involved in the gingerol-mediated protection of neuronal cells. HIF mediates cellular adaptations to low oxygen. Prolyl hydroxylase domain-containing protein 2 (PHD2) is an oxygen sensor that hydroxylates the HIF-α-subunit, promoting its proteasomal degradation under normoxic conditions. Thus, in the present study we wished to determine whether gingerol inhibits the catalytic activity of PHD2 and prevents HIF-1α protein proteasomal degradation, thereby preventing the occurrence of PrP (106-126)-induced neuronal apoptosis. We used the pharmacological inhibition of PHD2 by dimethyloxalylglycine (DMOG) or deferoxamine (DFO) and the genetic inhibition of HIF-1α by HIF-1α small interfering RNA (siRNA) to block the effects of gingerol against PrP (106-126)-induced neurotoxicity. Our results demonstrated that gingerol prevented PrP (106‑126)-induced neuronal apoptosis by upregulating HIF-1α and inhibiting the catalytic activity of PHD2 under normoxic conditions. Moreover, the protective effects of gingerol against PrP (106-126)-induced neuronal apoptosis were associated with the upregulation of the expression of cellular prion protein (PrPc). In conclusion, our results indicate that gingerol has therapeutic potential for use in the treatment or prevention of prion diseases, and its inhibitory effects on the catalytic activity of PHD2 may be of clinical benefit.

Show MeSH
Related in: MedlinePlus