MEF2D Mediates the Neuroprotective Effect of Methylene Blue Against Glutamate-Induced Oxidative Damage in HT22 Hippocampal Cells

Rutaecarpine alleviates migraine in nitroglycerin-induced mice by regulating PTEN/PGK1 signaling pathway to activate NRF2 antioxidant system

BACKGROUND

Due to its widespread prevalence, migraine is a common neurovascular condition that has a major impact on people's health and quality of life. Rutaecarpine (RUT) is one of the main effective components of Evodia rutaecarpa, which has a wide range of biological activities. However, the exact mechanism by which RUT improves migraine remain unknown.

PURPOSE

The purpose of this study was to investigate whether RUT improves migraine by inhibiting oxidative stress via activating the Nrf2 antioxidant system through the PTEN/PGK1 signaling pathway.

METHODS

In vivo, a mouse model of chronic migraine (CM) was established by repeated intraperitoneal injection of nitroglycerin (NTG). After treatment with RUT and Sumatriptan, behavioral tests were performed, followed by measurements of oxidative stress-related indicators in the trigeminal nucleus caudalis, expression of proteins associated with the Nrf2 antioxidant system, and the PTEN/PGK1 pathway. In vitro, PC12 cells were stimulated by 100 μM H2O2 for 24 h to induce oxidative stress, which was then treated with RUT. Furthermore, the role of PTEN in antioxidant stress of RUT was elucidated by knockout of the PTEN gene.

RESULTS

The results showed that RUT treatment improved NTG-induced migraine in mice by inhibiting oxidative stress. Importantly, RUT inhibited oxidative stress in NTG-induced mice or H2O2-induced PC12 cells via activating the Nrf2 antioxidant system by inhibiting PGK1 activity through PTEN. These results provide evidence that RUT improves migraine by activation of the Nrf2 antioxidant system through the PTEN/PGK1 pathway and provide new insights into the potential use of RUT as an effective drug development candidate for migraine.

An integrative analysis of miRNA and mRNA expression in the brains of Alzheimer's disease transgenic mice after real-world PM2.5 exposure

Fine particulate matter (PM_2.5) is associated with increased risks of Alzheimer's disease (AD), yet the toxicological mechanisms of PM_2.5 promoting AD remain unclear. In this study, wild-type and APP/PS1 transgenic mice (AD mice) were exposed to either filtered air (FA) or PM_2.5 for eight weeks with a real-world exposure system in Taiyuan, China (mean PM_2.5 concentration in the cage was 61 µg/m³). We found that PM_2.5 exposure could remarkably aggravate AD mice's ethological and brain ultrastructural damage, along with the elevation of the pro-inflammatory cytokines (IL-6 and TNF-α), Aβ-42 and AChE levels and the decline of ChAT levels in the brains. Based on high-throughput sequencing results, some differentially expressed (DE) mRNAs and DE miRNAs in the brains of AD mice after PM_2.5 exposure were screened. Using RT-qPCR, seven DE miRNAs (mmu-miR-193b-5p, 122b-5p, 466h-3p, 10b-5p, 1895, 384-5p, and 6412) and six genes (Pcdhgb8, Unc13b, Robo3, Prph, Pter, and Tbata) were evidenced the and verified. Two miRNA-target gene pairs (miR-125b-Pcdhgb8 pair and miR-466h-3p-IL-17Rα/TGF-βR2/Aβ-42/AChE pairs) were demonstrated that they were more related to PM_2.5-induced brain injury. Results of Gene Ontology (GO) pathways and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways predicted that synaptic and postsynaptic regulation, axon guidance, Wnt, MAPK, and mTOR pathways might be the possible regulatory mechanisms associated with pathological response. These revealed that PM_2.5-elevated pro-inflammatory cytokine levels and PM_2.5-altered neurotransmitter levels in AD mice could be the important causes of brain damage and proposed the promising miRNA and mRNA biomarkers and potential miRNA-mRNA interaction networks of PM_2.5-promoted AD.

Protective Function of Malus baccata (L.) Borkh Methanol Extract against UVB/Hydrogen Peroxide-Induced Skin Aging via Inhibition of MAPK and NF-κB Signaling

Ultraviolet (UV) irradiation induces ROS production, which activates activator protein (AP)-1 and nuclear factor (NF)-κB signaling and downstream molecules, ultimately triggering the generation of matrix metalloproteinases (MMPs) and degradation of collagen. The aim of this study was to investigate the protective effect of methanol extract from Malus baccata (L.) Borkh (Mb-ME) against aging. DPPH and ABTS assays showed that Mb-ME had a significant antioxidant capacity. Flow cytometry results indicated that Mb-ME attenuated UVB and H₂O₂-stimulated apoptosis and reactive oxygen species (ROS) generation. RT-PCR analysis in HaCaT and HDF cells suggested that Mb-ME treatment blocked the expression of MMPs, COX-2, IL-1β, IL-6, HYALs, and p53 while promoting the levels of TGM1, FLG, HASs, Sirt1, and Col1A1. Mechanically, Mb-ME inhibited the phosphorylation of MAP kinases and NF-κB signaling. Overall, these results strongly suggest that Mb-ME can be developed as an antiaging therapy.

Role of neurotoxicants in the pathogenesis of Alzheimer's disease: a mechanistic insight

Alzheimer's disease (AD) is the most conspicuous chronic neurodegenerative syndrome, which has become a significant challenge for the global healthcare system. Multiple studies have corroborated a clear association of neurotoxicants with AD pathogenicity, such as Amyloid beta (Aβ) proteins and neurofibrillary tangles (NFTs), signalling pathway modifications, cellular stress, cognitive dysfunctions, neuronal apoptosis, neuroinflammation, epigenetic modification, and so on. This review, therefore, aimed to address several essential mechanisms and signalling cascades, including Wnt (wingless and int.) signalling pathway, autophagy, mammalian target of rapamycin (mTOR), protein kinase C (PKC) signalling cascades, cellular redox status, energy metabolism, glutamatergic neurotransmissions, immune cell stimulations (e.g. microglia, astrocytes) as well as an amyloid precursor protein (APP), presenilin-1 (PSEN1), presenilin-2 (PSEN2) and other AD-related gene expressions that have been pretentious and modulated by the various neurotoxicants. This review concluded that neurotoxicants play a momentous role in developing AD through modulating various signalling cascades. Nevertheless, comprehension of this risk agent-induced neurotoxicity is far too little. More in-depth epidemiological and systematic investigations are needed to understand the potential mechanisms better to address these neurotoxicants and improve approaches to their risk exposure that aid in AD pathogenesis.Key messagesInevitable cascade mechanisms of how Alzheimer's Disease-related (AD-related) gene expressions are modulated by neurotoxicants have been discussed.Involvement of the neurotoxicants-induced pathways caused an extended risk of AD is explicited.Integration of cell culture, animals and population-based analysis on the clinical severity of AD is addressed.

Intravitreally Injected Methylene Blue Protects Retina against Acute Ocular Hypertension in Rats

Purpose: To assess the neuroprotective effects of methylene blue (MB) in a rat model of acute ocular hypertension (AOH) and explore its possible mechanisms.Methods: Our AOH rat model was obtained with anterior chamber perfusion for 60 min. After that, 100 μM MB was injected into the vitreous cavity immediately after injury. Electroretinogram, fundus photography, optical coherence tomography (OCT) and retina morphology examination were utilized to quantify retinal damage before surgery, as well as 7, 14 and 28 days after. The average number of surviving retinal ganglion cells (RGCs) was counted after fluorescent retrograde labelling with 4% DiI. And TUNEL assay was used to investigate retinal cell apoptosis at 24 hours after AOH. Nrf2 and BACE1 in the retina were determined by RT-qPCR analysis.Results: AOH did produce a severe degeneration effect on the whole retinal layer. Intravitreally injected MB maintained certain retinal thickness after AOH, reduced the destruction of electroretinograms, and enhanced RGCs survival. The average number of TUNEL-labelled cells statistically reduced in the MB-treated retina tissue compared with retina treated with normal saline. The relative mRNA level of Nrf2 was also much higher in the MB-treated retinas after AOH, and the expression of BACE1 had a decline in the AOH + MB group.Conclusions: MB can protect the retina from AOH injury and the possible mechanism might involve the inhibition of BACE1 expression and the activation of Nrf2 antioxidant pathway.

Isoflurane post-conditioning contributes to anti-apoptotic effect after cerebral ischaemia in rats through the ERK5/MEF2D signaling pathway

The mechanisms of brain protection during ischaemic reperfusion injury induced by isoflurane (ISO) post‐conditioning are unclear. Myocyte enhancement factor 2 (MEF2D) has been shown to promote neural survival in a variety of models, in which multiple survival and death signals converge on MEF2D and modulate its activity. Here, we investigated the effect of MEF2D on the neuroprotective effects of ISO post‐conditioning on rats after cerebral ischaemia/reperfusion (I/R) injury. Rats underwent middle cerebral artery occlusion (MCAO) surgery with ischaemia for 90 minutes and reperfusion for 24‐48 hours. After MCAO, neurological status was assessed at 12, 24 and 48 hours by the Modified Neurological Severity Score (mNSS) test. The passive avoidance test (PAT) was used to assess cognition function. Histological and neuropathological evaluations were performed with HE staining and Nissl's staining, respectively. We measured the expression of MEF2D, ERK5, GFAP and caspase‐3 by immunofluorescent staining and Western blotting, and TUNEL staining to assess the severity of apoptosis in hippocampal CA1 area. We found that MEF2D was involved in nerve protection after I/R injury, and post‐treatment of ISO significantly promoted the phosphorylation of ERK5, increased MEF2D transcriptional activity, inhibited the expression of caspase‐3 and played a role of brain protection.

MicroRNA-204-5p mediates sevoflurane-induced cytotoxicity in HT22 cells by targeting brain-derived neurotrophic factor

BACKGROUND

Sevoflurane is widely used as an inhalational anesthetic in clinical practice. However, sevoflurane can cause cytotoxicity and induce learning capacity decline in patients. A previous publication indicated that miR-204-5p might have a close relationship with sevoflurane-induced neurotoxicity. When exposed to sevoflurane, the expression of miR-204-5p in neonatal hippocampus of rats was significantly increased. Hence, we aimed to investigate the role of miR-204-5p in sevoflurane-induced neurotoxicity using a mouse hippocampal neuronal cell line (HT22).

METHODS

The levels of miR-204-5p in HT22 cells were detected by RT-qPCR. In addition, the effects of miR-204-5p on cell viability, apoptosis and proliferation were evaluated by CCK-8, flow cytometric, and immunofluorescence assay, respectively. Western blotting was used to detect expressions of Bax, Bcl-2, active caspase 3, BDNF, TrkB, p-TrkB, Akt and p-Akt in HT22 cells. ELISA assay was used to examine the levels of total superoxide dismutase (SOD), reduced glutathione (GSH), malondialdehyde (MDA) and reactive oxygen species (ROS) in cells. Meanwhile, the dual luciferase reporter system assay was employed to explore the interaction of miR-204-5p and BDNF in cells.

RESULTS

The level of miR-204-5p was increased in sevoflurane-treated HT22 cells. Moreover, downregulation of miR-204-5p inhibited sevoflurane-induced apoptosis and promoted cell proliferation by upregulating the proteins of Bcl-2 and downregulating the expressions of Bax and active caspase-3 in HT22 cells. In addition, inhibition of miR-204-5p alleviated sevoflurane-induced oxidative injuries in HT22 cells via decline of ROS and MDA and upregulation of SOD and GSH. Furthermore, bioinformatics and dual luciferase assay demonstrated that miR-204-5p can inhibit the TrkB/Akt pathway by targeting BDNF.

CONCLUSION

Our findings indicated that downregulation of miR-204-5p can decrease oxidative status in HT22 cells and alleviate sevoflurane-induced cytotoxicity through stimulating the BDNF/TrkB/Akt pathway. Therefore, miR-204-5p might be a potential biomarker and therapeutic target for the treatment of sevoflurane-induced neurotoxicity.

Methylene blue post-treatment improves hypoxia-ischemic recovery in a neonatal rat model

Recent work suggested that methylene blue (MB) has beneficial effects in a variety of neurological disorders, while its role in neonatal hypoxic-ischemic (HI) encephalopathy is still unclear. The current study was designed to investigate the effects of MB on HI-induced brain damage and its underlying mechanisms. The results showed that MB treatment can strongly attenuate HI-induced brain loss and neuronal damage in the cortex and hippocampus of neonatal rats. Further mechanistic analysis suggested that MB treatment was able to significantly reduce blood-brain barrier disruption after HI insult. In addition, MB profoundly inhibited microglia and astrocyte activation and the pro-inflammatory cytokines production in neonatal cortex and hippocampus after HI. Further, MB treatment resulted in dramatic suppression of oxidative damage, as evidenced by robustly decreased DHE and protein carbonyls levels in HI brain. Moreover, MB strongly preserved mitochondrial function by repressing HI-induced mitochondrial fragmentation, and the following neuronal death in cortex and hippocampus. Finally, behavioral tests revealed that MB significantly improved the spatial reference memory and motor coordination of neonatal HI rats. Taken together, these findings demonstrate that the mechanisms behind neuroprotective actions of methylene blue are multifactorial, including suppression of oxidative stress and neuroinflammation, restoration of mitochondrial function, as well as attenuation of blood-brain barrier disruption. Our study might provide further directions for MB as a promising option in neonatal HI encephalopathy therapy.

Mitochondria as a target for neuroprotection: role of methylene blue and photobiomodulation

Mitochondrial dysfunction plays a central role in the formation of neuroinflammation and oxidative stress, which are important factors contributing to the development of brain disease. Ample evidence suggests mitochondria are a promising target for neuroprotection. Recently, methods targeting mitochondria have been considered as potential approaches for treatment of brain disease through the inhibition of inflammation and oxidative injury. This review will discuss two widely studied approaches for the improvement of brain mitochondrial respiration, methylene blue (MB) and photobiomodulation (PBM). MB is a widely studied drug with potential beneficial effects in animal models of brain disease, as well as limited human studies. Similarly, PBM is a non-invasive treatment that promotes energy production and reduces both oxidative stress and inflammation, and has garnered increasing attention in recent years. MB and PBM have similar beneficial effects on mitochondrial function, oxidative damage, inflammation, and subsequent behavioral symptoms. However, the mechanisms underlying the energy enhancing, antioxidant, and anti-inflammatory effects of MB and PBM differ. This review will focus on mitochondrial dysfunction in several different brain diseases and the pathological improvements following MB and PBM treatment.

MEF2D upregulation protects neurons from oxygen-glucose deprivation/re-oxygenation-induced injury by enhancing Nrf2 activation

Accumulating evidence suggests that myocyte enhancer factor 2D (MEF2D) is a pro-survival factor for neurons. However, whether MEF2D is involved in protecting neurons from cerebral ischemia/reperfusion injury remains unknown. The current study was designed to investigate the exact role and mechanism of MEF2D in regulating oxygen-glucose deprivation/re-oxygenation (OGD/R)-induced neuronal injury, an in vitro model used to study cerebral ischemia/reperfusion injury. MEF2D expression was significantly induced in neurons in response to OGD/R injury. Functional analysis demonstrated that MEF2D upregulation significantly rescued the decreased viability of OGD/R-injured neurons and suppressed OGD/R-induced apoptosis and reactive oxygen species (ROS) production. By contrast, MEF2D knockdown increased the sensitivity of neurons to OGD/R-induced injury. Moreover, MEF2D overexpression increased the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and enhanced the activation of Nrf2 antioxidant signaling. However, Nrf2 knockdown partially blocked the MEF2D-mediated neuroprotective effect in OGD/R-exposed neurons. Overall, these results reveal that MEF2D overexpression attenuates OGD/R-induced injury by enhancing Nrf2-mediated antioxidant signaling. These findings suggest that MEF2D may serve as a neuroprotective target with a potential application for treatment of cerebral ischemia/reperfusion injury.

The Delayed Neuroprotective Effect of Methylene Blue in Experimental Rat Brain Trauma

After traumatic brain injury (TBI), an increase in dysfunction of the limbs contralateral to injury focus was observed. Using different behavioral tests, we found that a single intravenous injection of methylene blue (MB, 1 mg/kg) 30 min after the injury reduced the impairment of the motor functions of the limbs from 7 to 120 days after TBI. Administration of methylene blue 30 min after the injury and then monthly (six injections in total) was the most effective both in terms of preservation of limb function and duration of therapeutic action. This therapeutic effect was clearly manifested from the seventh day and continued until the end of the experiment-by the 180th day after TBI. MB is known to possess antioxidant properties; it has a protective effect against TBI by promoting autophagy and minimizing lesion volume in the first two weeks after TBI. Studies of the brains on the 180th day after TBI demonstrated that the monthly treatment of animals with MB statistically significantly prevented an increase in the density of microglial cells in the ipsilateral hemisphere and a decrease in the thickness of the corpus callosum in the contralateral hemisphere in comparison with untreated animals. However, on the 180th day after TBI, the magnetic resonance imaging scan of the animal brains did not show a significant reduction in the volume of the lesion in MB-treated animals. These findings are important for understanding the development of the long-term effects of TBI and expand the required therapeutic window for targeted neuroprotective interventions.

miR-217-regulated MEF2D-HDAC5/ND6 signaling pathway participates in the oxidative stress and inflammatory response after cerebral ischemia

Multiple factors are known to contribute to the pathogenesis of cerebral ischemic injury, including microRNAs (miRNAs). However, the precise mechanism of miRNAs involvement in cerebral ischemia remains largely unclear. In the current study, we found that miR-217 was significantly upregulated in ischemic stroke models, and the upregulation of miR-217 was associated with the development of post-stroke cognitive impairment. Further investigation revealed that myocyte enhancer factor 2D (MEF2D) was the direct target of miR-217. In vitro experiments showed that miR-217 promoted aggregation of histone deacetylase 5 (HDAC5) in cell nuclei by targeting MEF2D, which led to decreased expression of interleukin (IL)-10. In addition, miR-217 inhibited the expression of NADH dehydrogenase subunit 6 (ND6) in a MEF2D-dependent manner. Overexpression of MEF2D can reverse oxygen-glucose deprivation (OGD)-induced downregulation of ND6 and OGD-mediated neuronal apoptosis, and also reduce the elevated generation of reactive oxygen species (ROS) induced by OGD. Additionally, we found that in vivo administration of MEF2D overexpression plasmids increased IL-10 production and ameliorated cognitive impairment after cerebral ischemia. Taken together, these findings reveal a novel pathogenetic mechganism of cerebral ischemia-related brain injury involving the miR-217/MEF2D/HDAC5 axis and the miR-217/MEF2D/ND6 axis.

Protocatechuic acid attenuates β‑secretase activity and okadaic acid‑induced autophagy via the Akt/GSK‑3β/MEF2D pathway in PC12 cells

Okadaic acid (OA) can be used to induce an Alzheimer's disease (AD) model characterized by tau hyperphosphorylation, the formation of neurofibrillary tangles formation and β‑amyloid (Aβ) deposition. Previous studies have shown that the upregulation of Beclin‑1‑dependent autophagy may contribute to the elimination of aggregated Aβ. However, the effects of protocatechuic acid (PA) on the levels of Aβ42, phosphorylated (p)‑tau and β‑secretase in OA‑induced cell injury are unclear, and little is known concerning the role of the PA signaling pathway in the regulation of autophagy. The present study aimed to determine whether PA protects cells from OA‑induced cytotoxicity via the regulation of Beclin‑1‑dependent autophagy and its regulatory signaling pathway. PC12 cells were treated with OA with or without PA for 24 h. Enzymatic assays were performed to measure p‑tau, Aβ42 and β‑secretase activity. Western blotting was performed to detect p‑Akt, p‑glycogen synthase kinase‑3β (p‑GSK‑3β), Akt, GSK‑3β, myocyte enhancer factor 2D (MEF2D) and Beclin‑1 protein expression levels. Immunofluorescence and immunocytochemistry were used to measure Beclin‑1 expression levels. The results from this study showed that PA could increase cell viability and significantly decrease the levels of Aβ42, p‑tau, β‑secretase and Beclin‑1. PA can also promote the expression of p‑Akt and MEF2D while suppressing the expression of p‑GSK‑3β. These results indicated that PA protects PC12 cells from OA‑induced cytotoxicity, and attenuates autophagy via regulation of the Akt/GSK‑3β/MEF2D pathway, therefore potentially contributing to the neuroprotective effects of PA against OA toxicity. These findings suggested that PA may have potential as a drug candidate in preventative AD therapy.

MEF-2 isoforms' (A-D) roles in development and tumorigenesis

Myocyte enhancer factor (MEF)-2 plays a critical role in proliferation, differentiation, and development of various cell types in a tissue specific manner. Four isoforms of MEF-2 (A-D) differentially participate in controlling the cell fate during the developmental phases of cardiac, muscle, vascular, immune and skeletal systems. Through their associations with various cellular factors MEF-2 isoforms can trigger alterations in complex protein networks and modulate various stages of cellular differentiation, proliferation, survival and apoptosis. The role of the MEF-2 family of transcription factors in the development has been investigated in various cell types, and the evolving alterations in this family of transcription factors have resulted in a diverse and wide spectrum of disease phenotypes, ranging from cancer to infection. This review provides a comprehensive account on MEF-2 isoforms (A-D) from their respective localization, signaling, role in development and tumorigenesis as well as their association with histone deacetylases (HDACs), which can be exploited for therapeutic intervention.

Neurotoxic Agent-Induced Injury in Neurodegenerative Disease Model: Focus on Involvement of Glutamate Receptors

Glutamate receptors play a crucial role in the central nervous system and are implicated in different brain disorders. They play a significant role in the pathogenesis of neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Although many studies on NDDs have been conducted, their exact pathophysiological characteristics are still not fully understood. In in vivo and in vitro models of neurotoxic-induced NDDs, neurotoxic agents are used to induce several neuronal injuries for the purpose of correlating them with the pathological characteristics of NDDs. Moreover, therapeutic drugs might be discovered based on the studies employing these models. In NDD models, different neurotoxic agents, namely, kainic acid, domoic acid, glutamate, β-N-Methylamino-L-alanine, amyloid beta, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1-methyl-4-phenylpyridinium, rotenone, 3-Nitropropionic acid and methamphetamine can potently impair both ionotropic and metabotropic glutamate receptors, leading to the progression of toxicity. Many other neurotoxic agents mainly affect the functions of ionotropic glutamate receptors. We discuss particular neurotoxic agents that can act upon glutamate receptors so as to effectively mimic NDDs. The correlation of neurotoxic agent-induced disease characteristics with glutamate receptors would aid the discovery and development of therapeutic drugs for NDDs.

Substantial protection against MPTP-associated Parkinson's neurotoxicity in vitro and in vivo by anti-cancer agent SU4312 via activation of MEF2D and inhibition of MAO-B

We have previously demonstrated the unexpected neuroprotection of the anti-cancer agent SU4312 in cellular models associated with Parkinson's disease (PD). However, the precise mechanisms underlying its neuroprotection are still unknown, and the effects of SU4312 on rodent models of PD have not been characterized. In the current study, we found that the protection of SU4312 against 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced neurotoxicity in PC12 cells was achieved through the activation of transcription factor myocyte enhancer factor 2D (MEF2D), as evidenced by the fact that SU4312 stimulated myocyte enhancer factor 2 (MEF2) transcriptional activity and prevented the inhibition of MEF2D protein expression caused by MPP⁺, and that short hairpin RNA (ShRNA)-mediated knockdown of MEF2D significantly abolished the neuroprotection of SU4312. Additionally, Western blotting analysis revealed that SU4312 potentiated pro-survival PI3-K/Akt pathway to down-regulate MEF2D inhibitor glycogen synthase kinase-3beta (GSK3β). Furthermore, using the in vivo PD model of C57BL/6 mice insulted with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we found that intragastrical administration of SU4312 (0.2 and 1 mg/kg) greatly ameliorated Parkinsonian motor defects, and restored protein levels of MEF2D, phosphorylated-Ser473-Akt and phosphorylated-Ser9-GSK3β. Meanwhile, SU4312 effectively reversed the decrease in protein expression of tyrosine hydroxylase in substantia nigra pars compacta dopaminergic neurons, inhibited oxidative stress, maintained mitochondrial biogenesis and partially prevented the depletion of dopamine and its metabolites. Very encouragingly, SU4312 was able to selectively inhibit monoamine oxidase-B (MAO-B) activity both in vitro and in vivo, with an IC₅₀ value of 0.2 μM. These findings suggest that SU4312 provides therapeutic benefits in cellular and animal models of PD, possibly through multiple mechanisms including enhancement of MEF2D through the activation of PI3-K/Akt pathway, maintenance of mitochondrial biogenesis and inhibition of MAO-B activity. SU4312 thus may be an effective drug candidate for the prevention or even modification of the pathological processes of PD.