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Deoxygedunin, a natural product with potent neurotrophic activity in mice.

Jang SW, Liu X, Chan CB, France SA, Sayeed I, Tang W, Lin X, Xiao G, Andero R, Chang Q, Ressler KJ, Ye K - PLoS ONE (2010)

Bottom Line: Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities.Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner.Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA.

ABSTRACT
Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities. Here we report the discovery of deoxygedunin, which activates the mouse TrkB receptor and its downstream signaling cascades. Deoxygedunin is orally available and activates TrkB in mouse brain in a BDNF-independent way. Strikingly, it prevents the degeneration of vestibular ganglion in BDNF -/- pups. Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner. Further, administration of deoxygedunin into mice displays potent neuroprotective, anti-depressant and learning enhancement effects, all of which are mediated by the TrkB receptor. Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases.

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Related in: MedlinePlus

Deoxygedunin activates TrkB and protects neurons from apoptosis.(A) Deoxygedunin activates TrkB in primary hippocampal neurons. Hippocampal neurons were treated with 500 nM gedunin derivatives for 30 min and neurons were fixed and immunostained with rabbit polyclonal anti-p-TrkB (816) (1∶100) and anti-MAP2. The nuclei were stained with DAPI. BDNF and a few gedunin derivatives selectively triggered TrkB phosphorylation in neurons. (B) Deoxygedunin triggers TrkB activation in primary neurons. Rat cortical neurons were treated with various concentrations of deoxygedunin for 30 min. Neuronal lysates were subjected to immunoblotting analysis by mouse monoclonal anti-p-TrkB (817)(1∶20,000). Equal amount of TrkB was loaded (anti-TrkB from Biovision, 1∶1,000) (lower panel). (C) Deoxygedunin provokes Akt and Erk1/2 activation in primary neurons in a dose and time-dependent manner. Mouse monoclonal anti-TrkB 817 was used at 1∶20,000 dilution. (D) K252a blocks deoxygedunin's agonistic effect on TrkB. Cortical neurons were pretreated with K252a (100 nM) for 30 min, followed by BDNF (100 ng/ml) or deoxygedunin (500 nM) for 30 min. Cell lysates were analyzed by immunoblotting. (E) Deoxygedunin activates TrkB in mouse brain. Deoxygedunin (5 mg/kg) was intraperitoneally injected into mice and mouse brains were dislocated at different time points. Brain lysates were analyzed by immunoblotting.
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pone-0011528-g002: Deoxygedunin activates TrkB and protects neurons from apoptosis.(A) Deoxygedunin activates TrkB in primary hippocampal neurons. Hippocampal neurons were treated with 500 nM gedunin derivatives for 30 min and neurons were fixed and immunostained with rabbit polyclonal anti-p-TrkB (816) (1∶100) and anti-MAP2. The nuclei were stained with DAPI. BDNF and a few gedunin derivatives selectively triggered TrkB phosphorylation in neurons. (B) Deoxygedunin triggers TrkB activation in primary neurons. Rat cortical neurons were treated with various concentrations of deoxygedunin for 30 min. Neuronal lysates were subjected to immunoblotting analysis by mouse monoclonal anti-p-TrkB (817)(1∶20,000). Equal amount of TrkB was loaded (anti-TrkB from Biovision, 1∶1,000) (lower panel). (C) Deoxygedunin provokes Akt and Erk1/2 activation in primary neurons in a dose and time-dependent manner. Mouse monoclonal anti-TrkB 817 was used at 1∶20,000 dilution. (D) K252a blocks deoxygedunin's agonistic effect on TrkB. Cortical neurons were pretreated with K252a (100 nM) for 30 min, followed by BDNF (100 ng/ml) or deoxygedunin (500 nM) for 30 min. Cell lysates were analyzed by immunoblotting. (E) Deoxygedunin activates TrkB in mouse brain. Deoxygedunin (5 mg/kg) was intraperitoneally injected into mice and mouse brains were dislocated at different time points. Brain lysates were analyzed by immunoblotting.

Mentions: To examine whether deoxygedunin triggers TrkB signaling cascade, we conducted immunofluorescent staining and immunoblotting assays. The positive gedunin derivatives elicited TrkB activation in rat hippocampal neurons (Figure 2A). Among a few gedunin positive hits, deoxygedunin elicited the strongest stimulatory effect. Hence, we selected it and focused on this compound. Deoxygedunin activated TrkB in primary neuronal cultures in a dose-dependent manner (Figure 2B). In hippocampal neurons, deoxygedunin prominently provoked both Erk1/2 and Akt activation with a time course (Figure 2C, left panels). It stimulated both Erk1/2 and Akt activation in a dose-dependent manner. The minimal required drug concentration was about 100-250 nM (Figure 2C, right panels). Hence, the activation patterns of TrkB receptor and its downstream effectors including Akt and Erk1/2 by deoxygedunin were tightly correlated. K252a is a Trk receptors inhibitor. Pretreatment of K252a substantially blocked deoxygedunin-triggered TrkB activation in cortical neurons (Figure 2D), indicating that deoxygedunin can provoke TrkB autophosphorylation. Deoxygedunin-provoked downstream Akt signalings were also reduced by K252a. To assess whether deoxygedunin can provoke TrkB activation in the brain, we injected mice (i.p.) with a dose of 5 mg/kg for various time points. TrkB was selectively phosphorylated in the brain 2 h after injection, and peaked at 4–8 h, so was the downstream effectors Akt and Erk1/2 activation (Figure 2E, left panels), suggesting that deoxygedunin can penetrate the brain-blood barrier and stimulate TrkB activation. Deoxygedunin was also orally bioactive in provoking TrkB activation (Figure S2A). RT-PCR analysis revealed no change of TrkA or TrkB in mouse brain upon deoxygedunin treatment (Figure S2B), indicating that deoxygedunin stimulates TrkB activation independent of Trk receptor transcriptional alteration. Mouse monoclonal P-TrkB 817 antibody recognized both human and mouse TrkB phosphorylation in addition to rat TrkB (Figure S2C). Hence, deoxygedunin can strongly trigger TrkB activation in vitro and in vivo.


Deoxygedunin, a natural product with potent neurotrophic activity in mice.

Jang SW, Liu X, Chan CB, France SA, Sayeed I, Tang W, Lin X, Xiao G, Andero R, Chang Q, Ressler KJ, Ye K - PLoS ONE (2010)

Deoxygedunin activates TrkB and protects neurons from apoptosis.(A) Deoxygedunin activates TrkB in primary hippocampal neurons. Hippocampal neurons were treated with 500 nM gedunin derivatives for 30 min and neurons were fixed and immunostained with rabbit polyclonal anti-p-TrkB (816) (1∶100) and anti-MAP2. The nuclei were stained with DAPI. BDNF and a few gedunin derivatives selectively triggered TrkB phosphorylation in neurons. (B) Deoxygedunin triggers TrkB activation in primary neurons. Rat cortical neurons were treated with various concentrations of deoxygedunin for 30 min. Neuronal lysates were subjected to immunoblotting analysis by mouse monoclonal anti-p-TrkB (817)(1∶20,000). Equal amount of TrkB was loaded (anti-TrkB from Biovision, 1∶1,000) (lower panel). (C) Deoxygedunin provokes Akt and Erk1/2 activation in primary neurons in a dose and time-dependent manner. Mouse monoclonal anti-TrkB 817 was used at 1∶20,000 dilution. (D) K252a blocks deoxygedunin's agonistic effect on TrkB. Cortical neurons were pretreated with K252a (100 nM) for 30 min, followed by BDNF (100 ng/ml) or deoxygedunin (500 nM) for 30 min. Cell lysates were analyzed by immunoblotting. (E) Deoxygedunin activates TrkB in mouse brain. Deoxygedunin (5 mg/kg) was intraperitoneally injected into mice and mouse brains were dislocated at different time points. Brain lysates were analyzed by immunoblotting.
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Related In: Results  -  Collection

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pone-0011528-g002: Deoxygedunin activates TrkB and protects neurons from apoptosis.(A) Deoxygedunin activates TrkB in primary hippocampal neurons. Hippocampal neurons were treated with 500 nM gedunin derivatives for 30 min and neurons were fixed and immunostained with rabbit polyclonal anti-p-TrkB (816) (1∶100) and anti-MAP2. The nuclei were stained with DAPI. BDNF and a few gedunin derivatives selectively triggered TrkB phosphorylation in neurons. (B) Deoxygedunin triggers TrkB activation in primary neurons. Rat cortical neurons were treated with various concentrations of deoxygedunin for 30 min. Neuronal lysates were subjected to immunoblotting analysis by mouse monoclonal anti-p-TrkB (817)(1∶20,000). Equal amount of TrkB was loaded (anti-TrkB from Biovision, 1∶1,000) (lower panel). (C) Deoxygedunin provokes Akt and Erk1/2 activation in primary neurons in a dose and time-dependent manner. Mouse monoclonal anti-TrkB 817 was used at 1∶20,000 dilution. (D) K252a blocks deoxygedunin's agonistic effect on TrkB. Cortical neurons were pretreated with K252a (100 nM) for 30 min, followed by BDNF (100 ng/ml) or deoxygedunin (500 nM) for 30 min. Cell lysates were analyzed by immunoblotting. (E) Deoxygedunin activates TrkB in mouse brain. Deoxygedunin (5 mg/kg) was intraperitoneally injected into mice and mouse brains were dislocated at different time points. Brain lysates were analyzed by immunoblotting.
Mentions: To examine whether deoxygedunin triggers TrkB signaling cascade, we conducted immunofluorescent staining and immunoblotting assays. The positive gedunin derivatives elicited TrkB activation in rat hippocampal neurons (Figure 2A). Among a few gedunin positive hits, deoxygedunin elicited the strongest stimulatory effect. Hence, we selected it and focused on this compound. Deoxygedunin activated TrkB in primary neuronal cultures in a dose-dependent manner (Figure 2B). In hippocampal neurons, deoxygedunin prominently provoked both Erk1/2 and Akt activation with a time course (Figure 2C, left panels). It stimulated both Erk1/2 and Akt activation in a dose-dependent manner. The minimal required drug concentration was about 100-250 nM (Figure 2C, right panels). Hence, the activation patterns of TrkB receptor and its downstream effectors including Akt and Erk1/2 by deoxygedunin were tightly correlated. K252a is a Trk receptors inhibitor. Pretreatment of K252a substantially blocked deoxygedunin-triggered TrkB activation in cortical neurons (Figure 2D), indicating that deoxygedunin can provoke TrkB autophosphorylation. Deoxygedunin-provoked downstream Akt signalings were also reduced by K252a. To assess whether deoxygedunin can provoke TrkB activation in the brain, we injected mice (i.p.) with a dose of 5 mg/kg for various time points. TrkB was selectively phosphorylated in the brain 2 h after injection, and peaked at 4–8 h, so was the downstream effectors Akt and Erk1/2 activation (Figure 2E, left panels), suggesting that deoxygedunin can penetrate the brain-blood barrier and stimulate TrkB activation. Deoxygedunin was also orally bioactive in provoking TrkB activation (Figure S2A). RT-PCR analysis revealed no change of TrkA or TrkB in mouse brain upon deoxygedunin treatment (Figure S2B), indicating that deoxygedunin stimulates TrkB activation independent of Trk receptor transcriptional alteration. Mouse monoclonal P-TrkB 817 antibody recognized both human and mouse TrkB phosphorylation in addition to rat TrkB (Figure S2C). Hence, deoxygedunin can strongly trigger TrkB activation in vitro and in vivo.

Bottom Line: Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities.Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner.Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA.

ABSTRACT
Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities. Here we report the discovery of deoxygedunin, which activates the mouse TrkB receptor and its downstream signaling cascades. Deoxygedunin is orally available and activates TrkB in mouse brain in a BDNF-independent way. Strikingly, it prevents the degeneration of vestibular ganglion in BDNF -/- pups. Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner. Further, administration of deoxygedunin into mice displays potent neuroprotective, anti-depressant and learning enhancement effects, all of which are mediated by the TrkB receptor. Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases.

Show MeSH
Related in: MedlinePlus