Zinc Deficiency Decreases Neurite Extension via CRMP2 Signal Pathway.

Previous reports indicated that zinc deficiency could increase the risk of infectious diseases and developmental retardation in children. In experimental study, it has been reported that zinc deficiency during the embryonic period inhibited fetal growth, and disturbed neural differentiation and higher brain function later in adulthood. Although it has been suggested that zinc deficiency during development can have significant effects on neuronal differentiation and maturation, the molecular mechanisms of the effects of low zinc on neuronal differentiation during development have not been elucidated in detail. This study was performed to determine the effects of low zinc status on neurite outgrowth and collapsin response mediator protein 2 (CRMP2) signal pathway. Low zinc suppressed neurite outgrowth, and caused increase levels of phosphorylated CRMP2 (pCRMP2) relative to CRMP2, and decrease levels of phosphorylated glycogen synthase kinase 3ß (pGSK3ß) relative to GSK3ß in human neuroblastoma cell line (SH-SY5Y) cells on days 1, 2, and 3 of neuronal differentiation induction. Neurite outgrowth inhibited by low zinc was restored by treatment with the GSK3ß inhibitor CHIR99021. These results suggested that low zinc causes neurite outgrowth inhibition via phosphorylation of CRMP2 by GSK3ß. In conclusion, this study is the first to demonstrate that CRMP signaling is involved in the suppression of neurite outgrowth by low zinc.

Role of phosphate transporter PiT-2 in the pathogenesis of primary brain calcification.

Primary brain calcification (PBC), also known as idiopathic basal ganglia calcification (IBGC), primary familial brain calcification (PFBC) and so on, is a rare intractable disease characterized by abnormal mineral deposits, including mostly calcium in the basal ganglia, thalamus, and cerebellum. The causative gene of familial PBC is SLC20A2, which encodes the phosphate transporter PiT-2. Despite this knowledge, the molecular mechanism underlying SLC20A2-associated PBC remains unclear. In the present study, we investigated whether haploinsufficiency or a dominant-negative mechanism reduced Pi uptake in two PiT-2 variants (T115 M and R467X). We demonstrated that the presence of T115 M or R467X had no dominant-negative effect on Pi transport activity of wild-type (WT). In addition, the subcellular localization of R467X completely differed from that of WT, indicating that there is no interaction between R467X and WT. Conversely, T115 M and WT showed almost the same localization. Therefore, we examined the interaction between T115 M and WT using the bioluminescence resonance energy transfer (BRET) method. Although WT and T115 M interact with each other, T115 M does not inhibit WT's Pi transport activity. These results suggest that the role of SLC20A2 in the pathogenesis of PBC may involve decreased intracellular Pi uptake by a haploinsufficiency mechanism rather than a dominant-negative mechanism; agents promoting PiT-2 dimerization may be promising potential therapeutic agents for PBC.

PDGF-BB is involved in phosphate regulation via the phosphate transporters in human neuroblastoma SH-SY5Y cells.

Inorganic phosphate (Pi) is the second most abundant inorganic ion in the body. Since abnormalities in Pi metabolism are risk factors for various diseases, serum Pi levels are strictly controlled. Type-III sodium-dependent Pi transporters, PiT-1 (encoded by SLC20A1) and PiT-2 (encoded by SLC20A2), are distributed throughout the tissues of the body, including the central nervous system, and are known to be responsible for extracellular to intracellular Pi transport. Platelet-derived growth factor (PDGF) is a major growth factor of mesenchymal cells. PDGF-BB, a homodimer of PDGF-B, regulates intracellular Pi by increasing PiT-1 expression in vascular smooth muscle cells. However, the effects of PDGF-BB on Pi transporters in neurons have yet to be reported. Here, we investigated the effect of PDGF-BB on Pi transporters in human neuroblastoma SH-SY5Y cells. PDGF-BB did not induce SLC20A1 mRNA expression, but it increased the intracellular uptake of Pi via PiT-1 in SH-SY5Y cells. Among the signaling pathways associated with PDGF-BB, AKT signaling was shown to be involved in the increase in Pi transport. In addition, the PDGF-BB-induced increase in Pi mediated neuroprotective effects in SLC20A2-suppressed cells, in an in vitro model of the pathological condition found in idiopathic basal ganglia calcification. Moreover, the increase in Pi uptake was found to occur through promotion of intracellular PiT-1 translocation to the plasma membrane. Overall, these results indicate that PDGF-BB exerts neuroprotective effects via Pi transport, and they demonstrate the potential utility of PDGF-BB against abnormal Pi metabolism in neurons.

Characteristics and therapeutic potential of sodium-dependent phosphate cotransporters in relation to idiopathic basal ganglia calcification.

Type-III sodium-dependent phosphate transporters 1 and 2 (PiT 1 and PiT 2, respectively) are proteins encoded by SLC20A1 and SLC20A2, respectively. The ubiquitous distribution of SLC20A1 and SLC20A2 mRNAs in mammalian tissues supports the housekeeping maintenance and homeostasis of intracellular inorganic phosphate (Pi), which is absorbed from interstitial fluid for normal cellular functions. SLC20A2 variants have been found in patients with idiopathic basal ganglia calcification (IBGC), also known as Fahr's disease or primary familial brain calcification (PFBC). Thus, disrupted Pi homeostasis is considered one of the major factors in the pathogenic mechanism of IBGC. In this paper, among the causative genes of IBGC, we focused specifically on PiT2, and its potential for a therapeutic target of IBGC.

Kaempferol Has Potent Protective and Antifibrillogenic Effects for α-Synuclein Neurotoxicity In Vitro.

Aggregation of α-synuclein (α-Syn) is implicated in the pathogenesis of Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Therefore, the removal of α-Syn aggregation could lead to the development of many new therapeutic agents for neurodegenerative diseases. In the present study, we succeeded in generating a new α-Syn stably expressing cell line using a piggyBac transposon system to investigate the neuroprotective effect of the flavonoid kaempferol on α-Syn toxicity. We found that kaempferol provided significant protection against α-Syn-related neurotoxicity. Furthermore, kaempferol induced autophagy through an increase in the biogenesis of lysosomes by inducing the expression of transcription factor EB and reducing the accumulation of α-Syn; thus, kaempferol prevented neuronal cell death. Moreover, kaempferol directly blocked the amyloid fibril formation of α-Syn. These results support the therapeutic potential of kaempferol in diseases such as synucleinopathies that are characterized by α-Syn aggregates.

Moesin is involved in microglial activation accompanying morphological changes and reorganization of the actin cytoskeleton.

Moesin is a member of the ezrin, radixin and moesin (ERM) proteins that are involved in the formation and/or maintenance of cortical actin organization through their cross-linking activity between actin filaments and proteins located on the plasma membranes as well as through regulation of small GTPase activities. Microglia, immune cells in the central nervous system, show dynamic reorganization of the actin cytoskeleton in their process elongation and retraction as well as phagocytosis and migration. In microglia, moesin is the predominant ERM protein. Here, we show that microglial activation after systemic lipopolysaccharide application is partly inhibited in moesin knockout (Msn-KO) mice. We prepared primary microglia from wild-type and Msn-KO mice, and studied them to compare their phenotypes accompanying morphological changes and reorganization of the actin cytoskeleton induced by UDP-stimulated phagocytosis and ADP-stimulated migration. The Msn-KO microglia showed higher phagocytotic activity in the absence of UDP, which was not further increased by the treatment with UDP. They also exhibited decreased ADP-stimulated migration activities compared with the wild-type microglia. However, the Msn-KO microglia retained their ability to secrete tumor necrosis factor α and nitric oxide in response to lipopolysaccharide.

Neuroprotective effects of 5-aminolevulinic acid against neurodegeneration in rat models of Parkinson's disease and stroke.

Oxidative stress is associated with the progression of the neurodegenerative diseases Parkinson's disease (PD) and cerebral ischemia. Recently, 5-aminolevulinic acid (5-ALA), an intermediate in the porphyrin synthesis pathway, was reported to exert antioxidative effects on macrophages and cardiomyocytes. Here, we demonstrated the neuroprotective effects of 5-ALA using rat models of PD and ischemia as well as in vitro in SH-SY5Y cells. 5-ALA partially prevented neurodegeneration in each condition. These results suggest that 5-ALA has a potential for promising therapeutic agent to protect against neurodegeneration exacerbated by oxidative stress.

MicroRNA-5572 Is a Novel MicroRNA-Regulating SLC30A3 in Sporadic Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disease caused by the loss of motor neurons. Although the pathogenesis of sporadic ALS (sALS) remains unclear, it has recently been suggested that disorders of microRNA (miRNA) may be involved in neurodegenerative conditions. The purpose of this study was to investigate miRNA levels in sALS and the target genes of miRNA. Microarray and real-time RT-PCR analyses revealed significantly-decreased levels of miR-139-5p and significantly increased levels of miR-5572 in the spinal cords of sALS patients compared with those in controls. We then focused on miR-5572, which has not been reported in ALS, and determined its target gene. By using TargetScan, we predicted SLC30A3 as the candidate target gene of miR-5572. In a previous study, we found decreased SLC30A3 levels in the spinal cords of sALS patients. We revealed that SLC30A3 was regulated by miR-5572. Taken together, these results demonstrate that the level of novel miRNA miR-5572 is increased in sALS and that SLC30A3 is one of the target genes regulated by miR-5572.

Characteristics and Therapeutic Potential of Dental Pulp Stem Cells on Neurodegenerative Diseases.

To evaluate the therapeutic potential of stem cells for neurodegenerative diseases, emphasis should be placed on clarifying the characteristics of the various types of stem cells. Among stem cells, dental pulp stem cells (DPSCs) are a cell population that is rich in cell proliferation and multipotency. It has been reported that transplantation of DPSCs has protective effects against models of neurodegenerative diseases. The protective effects are not only through differentiation into the target cell type for the disease but are also related to trophic factors released from DPSCs. Recently, it has been reported that serum-free culture supernatant of dental pulp stem cell-conditioned medium (DPCM) contains various trophic factors and cytokines and that DPCM is effective for models of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic Lateral Sclerosis (ALS). Moreover, the use of stem cells from human exfoliated deciduous teeth (SHEDs) has been considered. SHEDs are derived from deciduous teeth that have been disposed of as medical waste. SHEDs have higher differentiation capacity and proliferation ability than DPSCs. In addition, the serum-free culture supernatant of SHEDs (SHED-CM) contains more trophic factors, cytokines, and biometals than DPCM and also promotes neuroprotection. The neuroprotective effect of DPSCs, including those from deciduous teeth, will be used as the seeds of therapeutic drugs for neurodegenerative diseases. SHEDs will be used for further cell therapy of neurodegenerative diseases in the future. In this paper, we focused on the characteristics of DPSCs and their potential for neurodegenerative diseases.

Partial reduced Pi transport function of PiT-2 might not be sufficient to induce brain calcification of idiopathic basal ganglia calcification.

Idiopathic basal ganglia calcification (IBGC) is a rare intractable disease characterized by abnormal mineral deposits, including mostly calcium in the basal ganglia, thalamus, and cerebellum. SLC20A2 is encoding the phosphate transporter PiT-2 and was identified in 2012 as the causative gene of familial IBGC. In this study, we investigated functionally two novel SLC20A2 variants (c.680C > T, c.1487G > A) and two SLC20A2 variants (c.82G > A, c.358G > C) previously reported from patients with IBGC. We evaluated the function of variant PiT-2 using stable cell lines. While inorganic phosphate (Pi) transport activity was abolished in the cells with c.82G > A, c.358G > C, and c.1487G > A variants, activity was maintained at 27.8% of the reference level in cells with the c.680C > T variant. Surprisingly, the c.680C > T variant had been discovered by chance in healthy members of an IBGC family, suggesting that partial preservation of Pi transport activity may avoid the onset of IBGC. In addition, we confirmed that PiT-2 variants could be translocated into the cell membrane to the same extent as PiT-2 wild type. In conclusion, we investigated the PiT-2 dysfunction of four SLC20A2 variants and suggested that a partial reduced Pi transport function of PiT-2 might not be sufficient to induce brain calcification of IBGC.

Functional evaluation of PDGFB-variants in idiopathic basal ganglia calcification, using patient-derived iPS cells.

Causative genes in patients with idiopathic basal ganglia calcification (IBGC) (also called primary familial brain calcification (PFBC)) have been reported in the past several years. In this study, we surveyed the clinical and neuroimaging data of 70 sporadic patients and 16 families (86 unrelated probands in total) in Japan, and studied variants of PDGFB gene in the patients. Variant analyses of PDGFB showed four novel pathogenic variants, namely, two splice site variants (c.160 + 2T > A and c.457-1G > T), one deletion variant (c.33_34delCT), and one insertion variant (c.342_343insG). Moreover, we developed iPS cells (iPSCs) from three patients with PDGFB variants (c.160 + 2T > A, c.457-1G > T, and c.33_34 delCT) and induced endothelial cells. Enzyme-linked immunoassay analysis showed that the levels of PDGF-BB, a homodimer of PDGF-B, in the blood sera of patients with PDGFB variants were significantly decreased to 34.0% of that of the control levels. Those in the culture media of the endothelial cells derived from iPSCs of patients also significantly decreased to 58.6% of the control levels. As the endothelial cells developed from iPSCs of the patients showed a phenotype of the disease, further studies using IBGC-specific iPSCs will give us more information on the pathophysiology and the therapy of IBGC in the future.

SLC20A2 variants cause dysfunctional phosphate transport activity in endothelial cells induced from Idiopathic Basal Ganglia Calcification patients-derived iPSCs.

Idiopathic Basal Ganglia Calcification (IBGC) is a rare neuropsychiatric illness also known as Fahr's disease or Primary Familial Brain Calcification (PFBC). IBGC is caused by SLC20A2 variants, which encodes the inorganic phosphate (Pi) transporter PiT-2, a transmembrane protein associated with Pi homeostasis. We have reported novel SLC20A2 variants in the Japanese population and established an induced pluripotent stem cells (iPSCs) from an IBGC patient carrying a SLC20A2 variant. To investigate the effect of these SLC20A2 variants identified in our previous study, we used Chinese hamster ovary (CHO) cells expressing these variant proteins using the Flp-In system (Flp-In CHO cells), and showed that variant SLC20A2 proteins significantly disrupted the Pi transport activity in Flp-In CHO cells. Endothelial cells (ECs) represent important target cells for elucidating the pathology of IBGC. Using patient-derived iPSCs in this study, we differentiated these cells into ECs and found no significant difference in their differentiation capacity into ECs compared with control iPSCs. However, the Pi transport activity of IBGC patient-derived iPS-ECs was significantly decreased compared with that of control iPS-ECs without changing the gene expression of the other SLC 20 family members. We confirmed that SLC20A2 variants caused the loss of function of the Pi transport activity in both Flp-In CHO cells and disease-specific iPSCs. This is the first report to show an in vitro model of iPSCs in IBGC with patient-identified SLC20A2 variants. These useful tools will help in elucidating IBGC pathogenesis and can be used for screening drug candidates.

A Golgi-targeting fluorescent probe for labile Fe(ii) to reveal an abnormal cellular iron distribution induced by dysfunction of VPS35.

Iron is involved in numerous physiologically essential processes in our body. However, excessive iron is a pathogenic factor in neurodegenerative diseases, causing aberrant oxidative stress. Divalent metal transporter 1 (DMT1) acts as a primary transporter of Fe(ii) ions. The intracellular delivery of DMT1 toward the cellular membrane via the trans-Golgi network during the endocytotic process is partially regulated by a retromer-mediated protein-sorting system comprising vacuolar protein-sorting proteins (VPSs). Thus, together with DMT1, the Golgi-apparatus acts as a hub organelle in the delivery system for intracellular Fe(ii) ions. Dysfunction of the VPS-relevant protein sorting system can induce the abnormal delivery of DMT1 toward lysosomes concomitantly with Fe(ii) ions. To explore this issue, we developed a fluorescent probe, Gol-SiRhoNox, for the Golgi-specific detection of Fe(ii) ions by integrating our original N-oxide-based Fe(ii)-specific chemical switch, a new Golgi-localizable chemical motif, and polarity-sensitive fluorogenic scaffold. Our synchronous imaging study using Gol-SiRhoNox and LysoRhoNox, a previously developed fluorescent probe for lysosomal Fe(ii), revealed that the intracellular distribution balance of Fe(ii) ions between the Golgi apparatus and lysosomes is normally Golgi-dominant, whereas the lysosome-specific elevation of Fe(ii) ions was observed in cells with induced dysfunction of VPS35, a member of the retromer complex. Treatment of cells with dysfunctional VPS35 with R55, a molecular chaperone, resulted in the restoration of the subcellular distribution of Fe(ii) ions to the Golgi-dominant state. These results indicate that the impairment of the DMT1 traffic machinery affects subcellular iron homeostasis, promoting Fe(ii) leakage at the Golgi and lysosomal accumulation of Fe(ii) through missorting of DMT1.

Effects of gem-dihydroperoxides against mutant copper­zinc superoxide dismutase-mediated neurotoxicity.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive muscle weakness, paralysis, and death. Although its neuropathology is well investigated, currently, effective treatments are unavailable. The mechanism of ALS involves the aggregation and accumulation of several mutant proteins, including mutant copper­zinc superoxide dismutase (SOD1), TAR DNA binding protein 43 kDa (TDP-43) and fused in sarcoma (FUS) proteins. Previous reports have shown that excessive oxidative stress, associated with mitochondrial dysfunction and mutant protein accumulation, contributes to ALS pathology. The present study focuses on the promotion of SOD1 misfolding and aggregation by oxidative stress. Having recently synthesized novel organic gem-dihydroperoxides (DHPs) with high anti-oxidant activity, we now examined whether DHPs reduce the mutant SOD1-induced intracellular aggregates involved in oxidative stress. We found that, among DHPs, 12AC2O significantly inhibited mutant SOD1-induced cell death and reduced the intracellular mutant SOD1 aggregates. Moreover, immunofluorescence staining with redox-sensitive dyes showed that 12AC2O reduced the excessive level of intracellular mutant SOD1-induced reactive oxygen species (ROS). Additionally, ESR analysis showed that 12AC2O exerts a direct scavenging effect against the hydroxyl radical (OH) and the superoxide anion (O2-). These results suggest that 12AC2O is a very useful agent in combination with other agents against ALS.

Inorganic phosphorus (Pi) in CSF is a biomarker for SLC20A2-associated idiopathic basal ganglia calcification (IBGC1).

INTRODUCTION: Idiopathic basal ganglia calcification (IBGC), also called Fahr's disease or recently primary familial brain calcification (PFBC), is characterized by abnormal deposits of minerals including calcium mainly and phosphate in the brain. Mutations in SLC20A2 (IBGC1 (merged with former IBGC2 and IBGC3)), which encodes PiT-2, a phosphate transporter, is the major cause of IBGC. Recently, Slc20a2-KO mice have been showed to have elevated levels of inorganic phosphorus (Pi) in cerebrospinal fluid (CSF); however, CSF Pi levels in patients with IBGC have not been fully examined. METHODS: We investigated the cases of 29 patients with IBGC including six patients with SLC20A2 mutation and three patients with PDGFB mutation, and 13 controls. The levels of sodium (Na), potassium (K), chloride (Cl), calcium (Ca), and Pi in sera and CSF were determined by potentiometry and colorimetry. Moreover, clinical manifestations were investigated in the IBGC patients with high Pi levels in CSF. RESULTS: The study revealed that the average level of Pi in the CSF of the total group of patients with IBGC is significantly higher than that of the control group, and the levels of Pi in CSF of the IBGC patients with SLC20A2 mutations are significantly higher than those of the IBGC patients with PDGFB mutations, the other IBGC patients and controls. CONCLUSION: Results of this study suggest that the levels of CSF Pi will be a good biomarker for IBGC1.

Therapeutic Activities of DJ-1 and Its Binding Compounds Against Neurodegenerative Diseases.

Parkinson's disease (PD) is a progressive neurodegenerative disorder that is primarily characterized by the degeneration of dopaminergic neurons in the nigrostriatal pathway. Loss-of-function mutations in the gene encoding PARK7/DJ-1 were identified in familial PD. Wild-type DJ-1 acts as an oxidative stress sensor in neural cells. Previously, we identified binding compounds of DJ-1, including UCP0045037/compound A, UCP0054278/compound B, and compound-23 (comp-23), by in silico virtual screening. These compounds prevented oxidative stress-induced dopaminergic neuronal death and restored locomotion defects in animal models of PD. In addition, these binding partners reduced infarct size in cerebral ischemia in rats. The neuroprotective effects of these compounds are lost in DJ-1-knockdown cells and DJ-1-knockout animal. These results suggest that these compounds interact with endogenous DJ-1 and then produce antioxidant and neuroprotective responses in both animal models for PD and cerebral ischemia in rats. This raises the possibility that interaction partners of DJ-1, such as UCP0045037, UCP0054278, and comp-23, may represent a novel dopaminergic neuroprotective drug for the treatment of PD.

Induced pluripotent stem cells derived from a patient with familial idiopathic basal ganglia calcification (IBGC) caused by a mutation in SLC20A2 gene.

Idiopathic basal ganglia calcification (IBGC), also known as Fahr disease or primary familial brain calcifications (PFBC), is a rare neurodegenerative disorder characterized by calcium deposits in basal ganglia and other brain regions, causing neuropsychiatric and motor symptoms. We established human induced pluripotent stem cells (iPSCs) from an IBGC patient. The established IBGC-iPSCs carried SLC20A2 c.1848G>A mutation (p.W616* of translated protein PiT2), and also showed typical iPSC morphology, pluripotency markers, normal karyotype, and the ability of in vitro differentiation into three-germ layers. The iPSC line will be useful for further elucidating the pathomechanism and/or drug development for IBGC.

Neuroprotective effect of 5-aminolevulinic acid against low inorganic phosphate in neuroblastoma SH-SY5Y cells.

PiT-1 (encoded by SLC20A1) and PiT-2 (encoded by SLC20A2) are type-III sodium-dependent phosphate cotransporters (NaPiTs). Recently, SLC20A2 mutations have been found in patients with idiopathic basal ganglia calcification (IBGC), and were predicted to bring about an inability to transport Pi from the extracellular environment. Here we investigated the effect of low Pi loading on the human neuroblastoma SH-SY5Y and the human glioblastoma A172 cell lines. The results show a different sensitivity to low Pi loading and differential regulation of type-III NaPiTs in these cells. We also examined whether 5-aminolevulinic acid (5-ALA) inhibited low Pi loading-induced neurotoxicity in SH-SY5Y cells. Concomitant application of 5-ALA with low Pi loading markedly attenuated low Pi-induced cell death and mitochondrial dysfunction via the induction of HO-1 by p38 MAPK. The findings provide us with novel viewpoints to understand the pathophysiology of IBGC, and give a new insight into the clinical prevention and treatment of IBGC.

Protective function of SLC30A10 induced via PERK-ATF4 pathway against 1-methyl-4-phenylpyridinium.

Solute carrier family 30 member 10 (SLC30A10) has been known as manganese transporter. It has been suggested that neurodegenerative diseases are related with cellular stress such as oxidative stress or endoplasmic reticulum (ER) stress. However, it remains unknown whether SLC30A10 is actually involved in several intracellular stress. We found that the level of Slc30a10 was increased in midbrain of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. Therefore, we further investigated the role of SLC30A10 in the 1-methyl-4-phenylpiridium ion (MPP+)-induced intracellular stress, and the molecular mechanism underlying SLC30A10 induction by MPP+ treatment. In human neuroblastoma cell line (SH-SY5Y) treated with MPP+ (1 mM), the SLC30A10 mRNA level was significantly increased, and in addition, the expression of CHOP, which is known as one of ER stress markers, was significantly increased by MPP+. Interestingly, the level of SLC30A10 mRNA was significantly increased by tunicamycin as an ER stressor, suggesting that the induction of SLC30A10 by MPP+ was caused via ER stress. Considering that PKR-like endoplasmic reticulum kinase (PERK) pathway is activated under ER stress induced by MPP+, we investigated whether the expression of SLC30A10 is increased through ATF4, which is major transcription factor in PERK pathway. The increase of SLC30A10 expression in MPP+-treated cells was eliminated by ATF4 knockdown. And the protective role of SLC30A10 against MPP+-induced ER stress was confirmed by measuring cell viability in SLC30A10 knockdown cells. In conclusion, SLC30A10 is thought to have protective role for MPP+-induced toxicity via PERK-ATF4 pathway.

DJ-1/PARK7: A New Therapeutic Target for Neurodegenerative Disorders.

DJ-1, encoded in a causative gene of familial Parkinson's disease (PARK7), has multiple functions: it works as an antioxidant, in transcriptional regulation, as a molecular chaperone and in protein degradation. Three types of pathogenic mutants of DJ-1 (M26I, D149A and L166P) have been reported to disrupt proper structures and lead to a loss of function. DJ-1 receives oxidation at the cysteine residue, and the degree of oxidation at the C106 residue determines DJ-1 activity. In this decade, DJ-1 has been reported to suppress the progression of various neurodegenerative disorders in animal models. The administration of recombinant wild-type DJ-1 protein suppresses the neuronal loss associated with both Parkinson's disease and ischemic stroke in rats. Furthermore, in studies focused on DJ-1 as the therapeutic target, compounds that have the capacity of binding to DJ-1 at the C106 residue have been reported to exert therapeutic effects on various neurodegenerative disorders such as Parkinson's disease, Alzheimer's disease and ischemic stroke. DJ-1 and DJ-1-targeting molecules/compounds will be useful therapeutic targets for various neurodegenerative disorders due to their various functions such as antioxidant capacity, chaperone function and as a proteolytic pathway.