Localization of the sperm protein SP22 and inhibition of fertility in vivo and in vitro

Effect of testicular degeneration on expression of sperm protein at 22 kDa in stallions

BACKGROUND

Sperm protein at 22 kDa has been associated with fertility.

OBJECTIVES

The objectives of this study were to determine (1) the localization pattern of SP22 on ejaculated and caudal epididymal equine spermatozoa and in epididymal fluid, and to (2) characterize SP22 protein and mRNA expression in testicular and epididymal tissues in response to heat-induced testicular degeneration.

MATERIALS AND METHODS

Semen was collected before and after hemi-castration, as well as prior to and following insulation of the remaining testes, and tissue specimens were collected for analysis.

RESULTS

Histopathology confirmed degeneration in insulated testes. Ejaculated and epididymal spermatozoa from samples collected prior to insulation of the testicles had a predominant staining pattern of SP22 over the equatorial region. However, the equatorial pattern in the pre-insulation epididymal semen samples was significantly lower than in the pre-insulation ejaculated semen samples (68 ± 3, 81 ± 2.6, respectively). Ejaculated and epididymal samples collected after insulation of the testicles showed a complete loss of staining as the predominant pattern. Western blot analysis verified the presence of SP22 on fresh ejaculated spermatozoa prior to and following heat-induced degeneration, on epididymal spermatozoa after testicular insulation, and in testicular and epididymal tissues. Heat insulation significantly reduced messenger RNA expression in the head of the epididymis and testicular tissues. Immunohistochemistry of the testicular and epididymal tissues pre-heating showed considerably weaker staining than the same tissues post-heating.

DISCUSSION AND CONCLUSION

It was concluded that heat-induced testicular damage causes both loss and relocation of SP22 on the sperm membrane. Future studies are warranted to determine the diagnostic value of these findings.

cDNA Cloning and Partial Characterization of the DJ-1 Gene from Tribolium castaneum

The DJ-1 gene is highly conserved across a wide variety of organisms and it plays a role in anti-oxidative stress mechanisms in cells. The red flour beetle, Tribolium castaneum, is widely used as a model insect species because it is easy to evaluate gene function in this species using RNA interference (RNAi). The T. castaneum DJ-1 (TcDJ-1) sequence is annotated in the T. castaneum genome database; however, the function and characteristics of the TcDJ-1 gene have not been elucidated. Here, we investigated the cDNA sequence of TcDJ-1 and partially characterized its function. First, we examined the TcDJ-1 amino acid sequence and found that it was highly conserved with sequences from other species. TcDJ-1 mRNA expression was higher in the early pupal and adult developmental stages. We evaluated oxidant tolerance in TcDJ-1 knockdown adults using paraquat and found that adults with TcDJ-1 knockdown exhibited increased sensitivity to paraquat. Our findings show that TcDJ-1 has an antioxidant function, as observed for DJ-1 from other insects. Therefore, these results suggest that TcDJ-1 protects against oxidative stress during metamorphosis.

Influence of Risk Factors for Male Infertility on Sperm Protein Composition

Male infertility is a common health problem that can be influenced by a host of lifestyle risk factors such as environment, nutrition, smoking, stress, and endocrine disruptors. These effects have been largely demonstrated on sperm parameters (e.g., motility, numeration, vitality, DNA integrity). In addition, several studies showed the deregulation of sperm proteins in relation to some of these factors. This review inventories the literature related to the identification of sperm proteins showing abundance variations in response to the four risk factors for male infertility that are the most investigated in this context: obesity, diabetes, tobacco smoking, and exposure to bisphenol-A (BPA). First, we provide an overview of the techniques used to identify deregulated proteins. Then, we summarise the main results obtained in the different studies and provide a compiled list of deregulated proteins in relation to each risk factor. Gene ontology analysis of these deregulated proteins shows that oxidative stress and immune and inflammatory responses are common mechanisms involved in sperm alterations encountered in relation to the risk factors.

Parkinson Disease Protein 7 (PARK7) Is Related to the Ability of Mammalian Sperm to Undergo In Vitro Capacitation

Parkinson disease protein 7 (PARK7) is a multifunctional protein known to be involved in the regulation of sperm motility, mitochondrial function, and oxidative stress response in mammalian sperm. While ROS generation is needed to activate the downstream signaling pathways required for sperm to undergo capacitation, oxidative stress has detrimental effects for sperm cells and a precise balance between ROS levels and antioxidant activity is needed. Considering the putative antioxidant role of PARK7, the present work sought to determine whether this protein is related to the sperm ability to withstand in vitro capacitation. To this end, and using the pig as a model, semen samples were incubated in capacitation medium for 300 min; the acrosomal exocytosis was triggered by the addition of progesterone after 240 min of incubation. At each relevant time point (0, 120, 240, 250, and 300 min), sperm motility, acrosome and plasma membrane integrity, membrane lipid disorder, mitochondrial membrane potential, intracellular calcium and ROS were evaluated. In addition, localization and protein levels of PARK7 were also assessed through immunofluorescence and immunoblotting. Based on the relative content of PARK7, two groups of samples were set. As early as 120 min of incubation, sperm samples with larger PARK7 content showed higher percentages of viable and acrosome-intact sperm, lipid disorder and superoxide levels, and lower intracellular calcium levels when compared to sperm samples with lower PARK7. These data suggest that PARK7 could play a role in preventing sperm from undergoing premature capacitation, maintaining sperm viability and providing a better ability to keep ROS homeostasis, which is needed to elicit sperm capacitation. Further studies are required to elucidate the antioxidant properties of PARK7 during in vitro capacitation and acrosomal exocytosis of mammalian sperm, and the relationship between PARK7 and sperm motility.

Effects of Obesity and Diabetes on Sperm Cell Proteomics in Rats

Infertility caused by male factors is potentially associated with metabolic disorders such as obesity and/or diabetes. This experimental study was conducted in a male rodent model to assess the effects of different diseases on semen quality and sperm proteomics. Ten Wistar rats were used for each treatment. Rats were fed commercial food provided controllably to the control group and the diabetic group, and a hypercaloric diet supplemented with 5% sucrose in water was provided ad libitum to the obese group for 38 weeks. Diabetes was induced with 35 mg/kg streptozotocin. After euthanasia, testicles, spermatozoa, fat, and blood (serum) samples were collected. Spermatozoa were evaluated for quality and subjected to proteomics analyses. Histology and cytology of the testis, and serum leptin, adiponectin, interleukin 8 (IL-8), blood glucose, and testosterone levels, were also assessed. Body weight, retroperitoneal and testicular fat, and the Lee index were also measured. Obesity and diabetes were induced. The diabetic group showed noticeable changes in spermatogenesis and sperm quality. The mass spectrometry proteomics data have been deposited in Mendeley Data (doi: 10.17632/rfp7kfjcsd.5). Fifteen proteins varied in abundance between groups, especially proteins related to energy production and structural function of the spermatozoa, suggesting disturbances in energy production with a subsequent alteration in sperm motility in both groups, but with a compensatory response in the obese group.

Differential seminal plasma proteome signatures of boars with high and low resistance to hypothermic semen preservation at 5°C

BACKGROUND

Hypothermic storage at 5°C has been investigated as an alternative to promote the prudent use of antibiotics for boar artificial insemination doses. However, this temperature is challenging for some ejaculates or boars.

OBJECTIVE

The present study aimed to identify putative biomarkers for semen resistance to hypothermic storage at 5°C by comparing the seminal plasma proteomes of boars with high and low seminal resistance to preservation at 5°C.

MATERIALS AND METHODS

From an initial group of 34 boars, 15 were selected based on the following criteria: ejaculate with ≤20% abnormal spermatozoa and at least 70% progressive motility at 120 hours of storage at 17°C. Then, based on the response to semen hypothermic storage at 5°C, boars were classified into two categories: high resistance-progressive motility of >75% in the three collections (n = 3); and low resistance-progressive motility of <75% in the three collections (n = 3). Seminal plasma proteins were analyzed in pools, and differential proteomics was performed using Multidimensional Protein Identification Technology.

RESULTS

Progressive motility was lower at 120 hours of storage in low resistance, compared to high resistance boars (P < .05). Acrosome and plasma membrane integrity were not affected by the boar category, storage time, or their interaction (P ≥ .104). Sixty-five proteins were considered for differential proteomics. Among the differentially expressed and exclusive proteins, the identification of proteins such cathepsin B, legumain, and cystatin B suggests significant changes in key enzymes (eg, metalloproteinases) involved in spermatogenesis, sperm integrity, and fertilizing potential.

DISCUSSION AND CONCLUSION

Differences in the seminal plasma suggest that proteins involved in the proteolytic activation of metalloproteinases and proteins related to immune response modulation could disrupt key cellular pathways during spermatogenesis and epididymal maturation, resulting in altered resistance to chilling injury. Further in vivo studies focusing on the immunological crosstalk between epithelial cells and gametes might explain how the immune regulators influence sperm resistance to hipothermic storage.

Imbalanced testicular metabolism induced by thyroid disorders: New evidences from quantitative proteome

Thyroid dysfunctions, such as hypothyroidism and hyperthyroidism, are the second most prevalent endocrinopathies and are associated to reproductive disorders in men. Several genes are differentially modulated by thyroid hormones in testes and imbalances in thyroid hormone levels are also associated to alterations on sperm functionality. Imbalances on antioxidant defense mechanism and stress oxidative have been pointed out as the main factors for the impairments on male reproductive function. To clarify this issue, we investigated the expression and activity of antioxidant enzymes in testis, followed by their proteomic profile in attempt to characterize the mechanisms involved in the alterations induced by hypo- or hyperthyroidism in adult male rats. Hypothyroidism reduced the Gsr transcript expression and the activity of CAT and GSR enzymes, while the hyperthyroidism reduced the Gpx4 var2 transcript expression. Among 1082 identified proteins, 123 and 37 proteins were downregulated by hypothyroidism compared to euthyroid and hyperthyroid condition, respectively, being 36 proteins commonly reduced in both comparisons and one exclusively in hypo-hyperthyroidism comparison. A network containing 29 nodes and 68 edges was obtained in protein-protein interaction analysis and the functional enrichment analysis of differentially expressed proteins revealed significant alterations for several functions in hypo-euthyroid and hypo-hyperthyroid comparisons, such as ATP metabolic process, coenzyme binding, sperm part, peroxiredoxin activity, mitochondrial protein complex, intramolecular oxidoreductase activity, binding of sperm to zona pellucida, glutathione transferase activity, response to testosterone. Thus, there is a correlation between thyroid disorders and impaired antioxidant defense mechanism, resulting in reproductive dysfunctions, as infertility, mainly observed in hypothyroidism.

Role of DJ-1 in Fertilization

Neither a sperm nor an egg can develop into an individual alone. Only when the sperm and egg bind and fuse, which is known as fertilization, can they acquire the ability of developing into new individuals. DJ-1 was reported to be involved in the process of fertilization.

Genetic polymorphisms and haplotypes of the DJ-1 gene promoter associated with the susceptibility to male infertility

PURPOSE

In this study, we evaluate the relationship between genetic polymorphisms of the DJ-1 gene, g.-6_+10del, and g.168_185del with male infertility susceptibility.

METHODS

Four hundred and twenty-two male infertile patients and 285 fertile male controls were recruited. Genotyping was performed by polymerase chain reaction. In silico analysis was performed by EPD, ElemeNT, SNPnexus, and PROMO to predict the potential functions of rs901561484 and rs373653682 polymorphisms.

RESULTS

The Del (D) allele carriers of DJ-1 g.-6_+10del polymorphism were significantly associated with the risk of male infertility in total infertile, asthenozoospermia, and oligoasthenozoospermia patients. Moreover, the Del (D) allele of DJ-1 g.-6_+10del polymorphism significantly increased in total male infertile, asthenozoospermia, and oligoasthenozoospermia groups. In addition, the frequencies of different genotypes and the Del allele and Dup allele carriers of DJ-1 g.168_185del gene polymorphisms were associated with male infertility in total infertile and four different sub-group patients. Furthermore, haplotype analysis of DJ-1 g.-6_+10del and g.168_185del polymorphisms revealed that the D-Dup and I-Del haplotype frequencies significantly increased the risk of male infertility, while I-Ins haplotypes were associated with a decreased risk of male infertility in total and sub-group patients. The in silico analysis showed that the presence of Ins and/or Dup alleles of the DJ-1 g.-6_+10del and g.168_185del polymorphisms could provide additional binding sites of more nuclear factors and probably affect transcriptional activity.

CONCLUSION(S)

Our study presents evidence of a strong association between functional polymorphisms of the DJ-1 promoter, g.-6_+10del, and g.168_185del with the risk of male infertility.

Protease activity of legumain is inhibited by an increase of cystatin E/M in the DJ-1-knockout mouse spleen, cerebrum and heart

Legumain (EC 3.4.22.34) is an asparaginyl endopeptidase. Legumain activity has been detected in various mouse tissues including the kidney, spleen and epididymis. Legumain is overexpressed in the majority of human solid tumors and transcription of the legumain gene is regulated by the p53 tumor suppressor in HCT116 cells. The legumain activity is also increased under acid conditions in Alzheimer's disease brains. DJ-1/PARK7, a cancer- and Parkinson's disease-associated protein, works as a coactivator to various transcription factors, including the androgen receptor, p53, PSF, Nrf2, SREBP and RREB1. Recently, we found that legumain expression, activation and cleavage of annexin A2 are regulated by DJ-1 through p53. In this study, we found that the expression levels of legumain mRNA were increased in the cerebrum, kidney, spleen, heart, lung, epididymis, stomach, small intestine and pancreas from DJ-1-knockout mice, although legumain activity levels were decreased in the cerebrum, spleen and heart from DJ-1-knockout mice. Furthermore, we found that cystatin E/M expression was increased in the spleen, cerebrum and heart from DJ-1-knockout mice. These results suggest that reduction of legumain activity is caused by an increase of cystatin E/M expression in the spleen, cerebrum and heart from DJ-1-knockout mice.

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Legumain is strongly activated in the epididymis from DJ-1-knockout mice.

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Expression level of legumain mRNA is increased but activity is decreased in the spleen, cerebrum and heart from DJ-1-knockout mice.

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Expression level of cystatin E/M is increased in the spleen, cerebrum and heart from DJ-1-knockout mice.

Localization of Fertility Factor SP22 to Specific Cell Types Within the Anterior Pituitary Gland

Sperm protein 22 (SP22) was recently identified in the anterior pituitary gland (AP) of male Golden Syrian hamsters using ion trap mass spectrometry. SP22 has been implicated in apoptosis, androgen receptor function, fertility, and ontogeny of early-onset Parkinson's disease. However, the role of SP22 in the pituitary has not been investigated. We cloned the cDNA for full-length SP22 from AP and posterior lobe (posterior pituitary and intermediate lobe) of the pituitary gland in adult male rats and Golden Syrian hamsters, confirming the presence of SP22 mRNA in the AP and posterior lobe. Because gonadal steroids are important regulators of AP function, and SP22 is associated with androgen receptor function, we used Western blots to compare SP22 in the AP of intact and orchidectomized male rats given placebo or a low or high dose of testosterone. SP22 did not differ with treatment, indicating that AP SP22 concentration was not regulated by testosterone. To localize SP22 to specific cells of the AP, mirror-image paraffin sections were labeled against SP22 and either luteinizing hormone (LH)β, thyroid-stimulating hormone (TSH)β, prolactin, adrenocorticotropic hormone (ACTH), or growth hormone (GH) using peroxidase-conjugated secondary antibody. Additional sections were colabeled with SP22 and one of the AP hormones using fluorescent secondary antibodies. SP22 colocalized in somatotropes and thyrotropes in rat and hamster. We identified SP22 in a small percentage of corticotropes, gonadotropes, and lactotropes. This is the first report that SP22 mRNA is present specifically in the AP, and SP22 is localized primarily in somatotropes and thyrotropes. SP22 may help regulate AP function and be particularly important for the control of GH and TSH secretion.

Sperm proteome and reproductive technologies in mammals

Sperm is highly differentiated cell that can be easily obtained and purified. Mature sperm is considered to be transcriptionally and translationally silent and incapable of protein synthesis. Recently, a large number of proteins have been identified in sperm from different species by using the proteomic approaches. Clinically, sperm proteins can be used as markers for male infertility due to different protein profiles identified in sperm from fertile and infertile male animals. Recent evidences have shown that the conditions of sperm preservation in vitro can also change the sperm protein profiles. This paper reviews the recent scientific publications available to address sperm proteome and their relationship with sperm cryopreservation, capacitation, fertilization, and separation of X and Y sperm. Future directions in the application of sperm proteomics to develop or optimize reproductive technologies in mammals are also discussed.

Seminal plasma proteins and their relationship with percentage of morphologically normal sperm in 2-year-old Brahman (Bos indicus) bulls

The objective was to determine the relationship between seminal plasma proteins and sperm morphology in Bos indicus bulls of the Brahman breed. Fifty-six 24-month-old Australian Brahman bulls were electroejaculated and samples were examined to determine the percentage of morphologically normal sperm (PNS24) and the seminal plasma protein composition was identified and quantified by 2-D gel electrophoresis. The total integrated optical density of 152 seminal plasma protein spots (SPPs) across all gels was determined using the PDQuest software version 8.0 (Bio Rad, USA). Using a single regression mixed model with the density of individual spots as a covariate for PNS24, 17 SPPs were significantly associated with PNS24 (p<0.05). A multiple regression analyses of these SPPs, using three models; non-parametric Tree Model, Generalized Additive Model, and a step-wise selection method were conducted, and 6 SPPs could be used to predict PNS24; four SPPs had positive and two had negative association with PNS24. Together these spots explained 35% of the phenotypic variation in PNS24. Using mass spectrometry (MALDI-ToF and TripleToF-MS) the SPPs with positive relationship contained mainly apolipoprotein A-I (1310), protein DJ-1 and glutathione peroxidase 3 (2308), phosphoglycerate kinase 1 (6402) and apolipoprotein A-I and secretoglobin family 1D member (8008). The SPPs inversely associated with PNS24 were clusterin/seminal plasma protein A3 (1411) and epididymal secretory protein E1 (8108). This is the first comprehensive report on the association between seminal plasma protein composition in Bos indicus Brahman bulls and sperm morphology.

PARK7 protein translocating into spermatozoa mitochondria in Chinese asthenozoospermia

PARK7 (DJ1) is a multifunctional oxidative stress response protein that protects cells against reactive oxygen species (ROS) and mitochondrial damage. PARK7 defects are known to cause various physiological dysfunctions, including infertility. Asthenozoospermia (AS), i.e. low-motile spermatozoa in the ejaculate, is a common cause of human male infertility. In this study, we found that downregulation of PARK7 resulted in increased levels of lipid peroxide and ROS, decreased mitochondrial membrane potential, and reduced mitochondrial complex I enzyme activity in the spermatozoa from AS patients. Furthermore, it was observed that PARK7 was translocated into the mitochondria of damaged spermatozoa in AS. Finally, we examined the oxidative state of PARK7 and the results demonstrated the enhancement of oxidation, expressed by increased sulfonic acid residues, the highest form of oxidation, as the sperm motility decreased. Taken together, these results revealed that PARK7 deficiency may increase the oxidative stress damage to spermatozoa. Our present findings open new avenues of therapeutic intervention targeting PARK7 for the treatment of AS.

Identification of an artificial peptide motif that binds and stabilizes reduced human DJ-1

Although the precise biochemical function of DJ-1 remains unclear, it has been found to exert cytoprotective activity against oxidative stress. Cys106 is central to this function since it has a distinctly low pK(a) rendering it extremely susceptible for oxidation. This characteristic, however, also poses a severe hindrance to obtain reduced DJ-1 for in vitro investigation. We have developed an approach to produce recombinant human DJ-1 in its reduced form as a bona fide basis for exploring the redox capacities of the protein. We solved the crystal structure of this DJ-1 at 1.56Å resolution, allowing us to capture Cys106 in the reduced state for the first time. The dimeric structure reveals one molecule of DJ-1 in its reduced state while the other exhibits the characteristics of a mono-oxygenated cysteine. Comparison with previous structures indicates the absence of redox dependent global conformational changes in DJ-1. The capture of reduced Cys106 is facilitated by stabilization within the putative active site achieved through a glutamate side chain. This side chain is provided by a crystallographic neighbor as part of a 'Leu-Glu' motif, which was added to the C-terminus of DJ-1. In the structure this motif binds DJ-1 in close proximity to Cys106 through extended hydrophilic and hydrophobic interactions depicting a distinct binding pocket, which can serve as a basis for compound development targeting DJ-1.

Proteome analysis and genome-wide regulatory motif prediction identify novel potentially sex-hormone regulated proteins in rat efferent ducts

The efferent ducts are a series of tubules that conduct sperm from the rete testis to the epididymis. They absorb most fluid and proteins originating from the rete testis during concentration of spermatozoa prior to their entry into the epididymis. Proteome analysis of micro-dissected efferent duct samples from adult rats was combined with genome-wide computational prediction of conserved hormone response elements to identify factors likely regulated by oestrogens and androgens. We identified 165 proteins and found subsets of the promoters controlling their corresponding genes to contain androgen- and oestrogen response elements (ARE/EREs) at similar frequencies. Moreover, EREs were significantly enriched among the loci identified compared with their genome-wide occurrence. The expression and localization of Anxa6, Ckb, Krt19, Park7, Pdzk1 and Tpt1 in the efferent ducts and other related hormone controlled tissues was further validated at the RNA or protein level. This study identifies many novel proteins predicted to play roles in sperm maturation and male fertility and provides significant computational evidence that the efferent ducts express genes transcriptionally controlled by sex hormones.

Antisperm immunity and infertility

Immunoinfertility is one of several causes of infertility in humans. Although progress on antisperm immunity and infertility has advanced during the past three decades, the nature of a real antisperm antibody (ASA) is still poorly understood. Dozens of sperm antigens have been isolated and characterized in association with infertility. However, it is difficult to identify a single predominant target antigen that could interact with all the ASAs. There are some protective mechanisms preventing ASA production in males and females. As chronic infection, vasectomy and vasovasostomy, heavy metals, and testicular cancer and torsion may induce the production of ASAs, they may be responsible for decreased motility and sperm penetration of cervical mucus, and the blockage of the acrosome reaction and the sperm-egg interaction. Many ASA assay methods have been developed, each with advantages and disadvantages. Efforts for the treatment of ASA-mediated infertility have been attempted. However, current therapy for ASA-associated infertility is almost empiric and largely unproven.

Parkinson disease protein DJ-1 converts from a zymogen to a protease by carboxyl-terminal cleavage

Mutations in DJ-1 cause recessively transmitted early-onset Parkinson disease (PD), and oxidative damage to DJ-1 has been associated with the pathogenesis of late-onset sporadic PD. The precise biochemical function of DJ-1 remains elusive. Here, we report that DJ-1 is synthesized as a latent protease zymogen with low-intrinsic proteolytic activity. DJ-1 protease zymogen is activated by the removal of a 15-amino acid peptide at its C terminus. The activated DJ-1 functions as a cysteine protease with Cys-106 and His-126 as the catalytic diad. We show that endogenous DJ-1 in dopaminergic cells undergoes C-terminal cleavage in response to mild oxidative stress, suggesting that DJ-1 protease activation occurs in a redox-dependent manner. Moreover, we find that the C-terminally cleaved form of DJ-1 with activated protease function exhibits enhanced cytoprotective action against oxidative stress-induced apoptosis. The cytoprotective action of DJ-1 is abolished by the C106A and H126A mutations. Our findings support a role for DJ-1 protease in cellular defense against oxidative stress and have important implications for understanding and treating PD.

DJ-1 and prevention of oxidative stress in Parkinson's disease and other age-related disorders

Mutations in the PARK7/DJ-1 gene are rare causes of autosomal-recessive hereditary Parkinson's disease. Loss-of-function mutations lead to the characteristic selective neurodegeneration of nigrostriatal dopaminergic neurons, which accounts for parkinsonian symptoms. Originally identified as an oncogene, DJ-1 is a ubiquitous redox-responsive cytoprotective protein with diverse functions. In addition to cell-autonomous neuroprotective roles, DJ-1 may act in a transcellular manner, being up-regulated in reactive astrocytes in chronic neurodegenerative diseases as well as in stroke. Thus, DJ-1, particularly in its oxidized form, has been recognized as a biomarker for cancer and neurodegenerative diseases. The crystal structure of DJ-1 has been solved, allowing detailed investigations of the redox-reactive center of DJ-1. Structure-function studies revealed that DJ-1 may become activated in the presence of reactive oxygen species, under conditions of oxidative stress, but also as part of physiological receptor-mediated signal transduction. DJ-1 regulates redox signaling kinase pathways and acts as a transcriptional regulator of antioxidative gene batteries. Therefore, DJ-1 is an important redox-reactive signaling intermediate controlling oxidative stress after ischemia, upon neuroinflammation, and during age-related neurodegenerative processes. Augmenting DJ-1 activity might provide novel approaches to treating chronic neurodegenerative illnesses such as Parkinson's disease and acute damage such as stroke.

Association of DJ-1 with chaperones and enhanced association and colocalization with mitochondrial Hsp70 by oxidative stress

DJ-1 is a novel oncogene and causative gene for familial form of the Parkinson's disease (PD). DJ-1 has been shown to play a role in anti-oxidative stress by eliminating reactive oxygen species (ROS). The onset of PD is thought to be caused by oxidative stress and mitochondrial injury, which leads to protein aggregation that results in neuronal cell death. However, the mechanism by which DJ-1 triggers the onset of PD is still not clear. In this study, we analyzed association and localization of DJ-1 and its mutants with various chaperones. The results showed that DJ-1 and its mutants were associated with Hsp70, CHIP and mtHsp70/Grp75, a mitochondria-resident Hsp70, and that L166P and M26I mutants found in PD patients were strongly associated with Hsp70 and CHIP compared to wild-type and other DJ-1 mutants. DJ-1 and its mutants were colocalized with Hsp70 and CHIP in cells. Furthermore, association and colocalization of wildtype DJ-1 with mtHsp70 in mitochondria were found to be enhanced by treatment of cells with H2O2. These results suggest that translocation of DJ-1 to mitochondria after oxidative stress is carried out in association with chaperones.

Characterization of a novel, testis-specific equine serine/threonine kinase

Testis-specific protein kinases are important because of their potential role in spermiogenesis, sperm maturation, and sperm function. In the present study, a novel serine-threonine kinase with high identity to human serine-threonine kinase 31 (STK31) was cloned from equine testis and expression of the protein was characterized in equine testis and ejaculated spermatozoa. Five over-lapping independent clones were plaque purified after screening of a lambda ZAP cDNA expression library constructed from equine testis. Sequence analysis and alignment of all five clones showed high identity with human STK31 with approximately 200 bp of the equine N-terminal sequence incomplete. The putative full-length coding sequence of this testis specific equine cDNA was completed by amplification of a 200-bp fragment using a human primer upstream of the reported translational start site with equine specific nested primers. Northern blot analysis using the equine STK31 cDNA detected an RNA transcript of approximately 3.1 kb present in testis but not in other reproductive or somatic tissues. Immunolocalization of the protein in equine testis and spermatozoa demonstrated that STK31 was present in post-meiotic germ cells with localization to the equatorial segment of testicular spermatozoa. Analysis of the domain structure of equine STK31 revealed a protein kinase domain along with a putative RNA-binding region. The post-meiotic expression of this protein along with its domain structure suggests that STK31 may have a role in reorganization of sperm chromatin during spermiogenesis. The cloning of this novel, testis-specific equine STK provides a new tool to explore the role of kinases in sperm function.

DJ-1, a causative gene product of a familial form of Parkinson's disease, is secreted through microdomains

DJ-1 is secreted into the serum and plasma of patients with various diseases. In this study, DJ-1 was found to be secreted into culture media of various cells and the amount of wild-type DJ-1 secreted was two-fold greater than that of mutant DJ-1 of cysteine at 106 (C106). Furthermore, the oxidative status of more than 90% of the DJ-1 secreted from HeLa cells was SOH and SO2H forms of C106. A portion of DJ-1 in cells was localized in microdomains of the membrane. These findings suggest that DJ-1 is secreted through microdomains and that oxidation of DJ-1 at C106 facilitates the secretion.

Secretion of DJ-1 into the serum of patients with Parkinson's disease

DJ-1 was initially identified by us as a novel oncogene and has later been found to be a causative gene for familial Parkinson's disease PARK7. DJ-1 plays role in transcriptional regulation and in oxidative stress function, and loss of its function is thought to be related to onset age, mode of progression and clinical severity of both familial and sporadic forms of Parkinson's disease (PD). DJ-1 is localized both in the cytoplasm and nucleus, and it has been reported to be secreted into the serum or plasma of patients with breast cancer, melanoma, familial amyloidotic polyneuropathy and stroke. In this study, levels of DJ-1 secreted into the serum of healthy controls and patients with sporadic PD were examined by using a DJ-1 ELISA kit, and the level of oxidative stress in the serum was also measured. The results showed that DJ-1 was secreted into the serum of both healthy controls and PD patients. There was no significant difference between the levels of secreted DJ-1 in two groups, and correlations of levels of secreted DJ-1 with age, clinical severity of PD and level of oxidative stress were not found.

Inhibition of sperm-egg binding and fertilisation in mice by a monoclonal antibody reactive to 57-kDa human sperm surface antigen

Monoclonal antibodies (mAbs) against spermatozoa are a popular approach to define sperm antigens involved in the process of fertilisation. The identification and characterisation of a 57-kDa fertility asssociated sperm antigen (FASA-57) from human spermatozoa was reported in an earlier paper by the authors. In the present report, studies to develop mAbs against partially purified FASA-57 are extended. From a panel of mAbs raised, one clone designated as 3H(4)B(9) was selected and characterised because it recognised native FASA-57. Indirect immunofluorescence studies revealed that FASA-57 localised on the acrosome of non-acrosome-reacted human spermatozoa and on the equatorial region after the acrosome reaction. Spermatozoa from several other mammalian species were also found to express this antigen, suggesting its evolutionary conservation across the species. The antigen localised specifically in spermatogonial cells and luminal spermatozoa of the testis and epididymis. Western blot studies showed the presence of a FASA-57-like protein in the mouse brain also, indicating that testis and brain share antigenic similarities. Further, the role of FASA-57 in sperm-egg interaction was investigated using a mouse model. The mAb 3H(4)B(9) inhibited sperm-egg binding and fusion in a dose-dependent manner with half-maximal inhibition at 2 microg mL(-1). In conclusion, FASA-57 appears to play an important role in sperm-egg recognition, fusion and fertilisation. Therefore, FASA-57 could be used as a diagnostic marker in the evaluation of male infertility.

Protection against nonylphenol-induced cell death by DJ-1 in cultured Japanese medaka (Oryzias latipes) cells

The Japanese medaka (Oryzias latipes) has been used to investigate diverse aspects of toxicology, genetics and developmental biology and to monitor biological changes caused by endocrine disruptors. In this study, we analyzed a medaka homolog of human DJ-1 (meDJ-1) in cultured medaka cells into which nonylphenol (NP) was added. Like human DJ-1, meDJ-1 was found to be oxidized by treatment with H(2)O(2) and its pI was shifted to acidic points. NP was found to induce cell death with kinetics similar to that of H(2)O(2) in cultured medaka OLHE-13 cells. After OLHE-13 cells had been treated with sub-lethal concentrations of H(2)O(2) and NP, production of reactive oxygen species and oxidation of meDJ-1 were observed. meDJ-1 knockdown by short interfering RNA rendered OLHE-13 cells susceptible to H(2)O(2) and NP-induced cell death, suggesting a protective role of DJ-1 against oxidative stress-induced cell death in medaka cells. These results suggest that meDJ-1 is a suitable biomarker for oxidative stress reactions in medaka.

Specific cleavage of DJ-1 under an oxidative condition

DJ-1 was initially identified by us as a novel oncogene and has recently been found to be a causative gene for familial Parkinson's disease (PD) PARK7. DJ-1 plays roles in transcriptional regulation and in oxidative stress function, and its oxidative state at cysteine residues determines activities of DJ-1. In this study, we found that recombinant DJ-1 expressed in and purified from E. coli was specifically cleaved between glycine and proline at amino acid numbers 157 and 158, respectively, by treatment of DJ-1 with H2O2. A substitution mutant of DJ-1 from cysteine to serine at amino acid number 106, a major oxidation site of DJ-1, was found not to be cleaved under an oxidative condition, suggesting oxidation-dependent cleavage of DJ-1. Cleavage of DJ-1 was also observed in human SH-SY5Y cells that had been treated with H2O2. These results suggest that oxidative stress-induced cleavage of DJ-1 regulates functions of DJ-1.

Establishment of specific antibodies that recognize C106-oxidized DJ-1

DJ-1 was initially identified by us as a novel oncogene and has recently been found to be a causative gene for familial Parkinson's disease PARK7. DJ-1 plays roles in transcriptional regulation and in oxidative stress function, and its oxidative state at the cysteine residue 106 (C106) determines activities of DJ-1. Elevated levels of oxidation of DJ-1 were observed in brain tissues of patients with Parkinson's disease (PD) and patients with Alzheimer's disease (AD). In this study, we established specific antibodies using synthetic peptide containing SO(3)H at C106 of DJ-1 as an immunogen. These antibodies were found by Western blot analysis to recognize DJ-1 specifically oxidized at C106 but not at other cysteines. These antibodies should be useful to study pathophysiologies of PD and AD.

Proper SUMO-1 conjugation is essential to DJ-1 to exert its full activities

DJ-1 is a multifunctional protein that plays roles in transcriptional regulation and antioxidative stress, and loss of its function is thought to result in the onset of Parkinson's disease (PD). Here, we report that DJ-1 was sumoylated on a lysine residue at amino-acid number 130 (K130) by PIASxalpha or PIASy. The K130 mutation abrogated all of the functions of DJ-1, including ras-dependent transformation, cell growth promotion and anti-UV-induced apoptosis activities. Sumoylation of DJ-1 was increased after UV irradiation concomitant with a pI shift to an acidic point of DJ-1. Furthermore, L166P, a mutant DJ-1 found in PD patients, and K130RX, an artificial mutant containing four mutations in DJ-1, were improperly sumoylated, and they became insoluble, partly localized in the mitochondria and degraded by the proteasome system. Both L166P-expressing cells and DJ-1-knockdown cells were found to be highly susceptible to UV-induced cell apoptosis.

DJ-1 interacts with HIPK1 and affects H2O2-induced cell death

DJ-1 is a novel oncogene and causative gene for the familial form of Parkinson's disease (PD). DJ-1 has multiple functions, including anti-oxidative stress by eliminating reactive oxygen species (ROS) and transcriptional regulation as a coactivator, and loss of these functions are thought to trigger the onset of PD. The mechanism underlying the prevention of cell death by DJ-1 is, however, not clear. In this study, we found that DJ-1 directly bound to homeodomaininteracting protein kinase 1 (HIPK1) in vitro and in vivo and that these proteins were colocalized in the nucleus. HIPK1 was then found to be degraded in human H1299 cells transfected with wild-type DJ-1 but not with a C106S DJ-1 mutant, a DJ-1 protein disrupting a catalytic domain of the putative protease, in a dose-dependent manner. Furthermore, although knockdown of either DJ-1 or HIPK1 rendered H1299 cells susceptible to H2O2-induced cell death, double-knockdown of DJ-1 and HIPK1 rendered H1299 cells resistant to H2O2-induced cell death, suggesting that the elevated level of HIPK1 induced by a low level of DJ-1 inhibits oxidative stress-induced cell death.

Expression profiles of genes in DJ-1-knockdown and L166P DJ-1 mutant cells

DJ-1 is a novel oncogene and a causative gene for the familial form of Parkinson's disease (PD). DJ-1 has been shown to play roles in anti-oxidative stress by eliminating reactive oxygen species and in transcriptional regulation of genes. Loss of these functions of DJ-1 is thought to trigger the onset of PD. In this study, to identify genes for which expressions are regulated by DJ-1, DNA microarray analyses were carried out using two mouse NIH3T3 cell lines, DJ-1-knockdown cells and cells harboring an exogenously added L 166 P DJ-1 mutant found in PD patients. In both cell lines, drastic changes in expressions of genes, including genes related to stress, apoptosis, oxidative stress and neurotoxicity, were observed and changes in expressions were confirmed by RT-PCR. Of the genes identified, expression level of the extracellular superoxide dismutase (SOD 3) gene was found to decrease in DJ-1-knockdown cells, while expressions of SOD 1 and SOD 2 genes did not change. Furthermore, expression of the tau gene, a gene whose product gives cells neurotoxicity by aggregation, was found to increase at its promoter level in L 166 P DJ-1 cells. These findings suggest that DJ-1 regulates expressions of genes for which functions are thought to be related to cell death or neurodegeneration.

Hamster contraception associated protein 1 (CAP1)

Based on cDNA and amino acid sequence, we demonstrate that hamster contraception associated protein 1 (CAP1) protein (an homolog of DJ-1 in mouse, CAP1/SP22/RS in rat and DJ-1/RS in human) is conserved during evolution. Through solubilization studies, it was demonstrated that hamster CAP1 has a peripheral membrane localization. SDS-PAGE analysis revealed that the migration pattern for hamster CAP1 compared to the other rodent counterparts, rat and mouse was different; indicating species-specific differences in the protein (possibly due to post-translational modifications). This protein also shows a ubiquitous presence in both somatic and germ tissues, and has been localized to the sperm tail. It was noticed that hamster CAP1 was lost from the mid piece of spermatozoa during capacitation. Interestingly, following in vitro treatment with ornidazole, CAP1 was lost from the spermatozoa and immunofluorescence studies showed that the major loss was from the mid piece of the spermatozoa. Another interesting feature highlighted about hamster CAP1 is its tendency to exist in two pI isoforms. Summarily, hamster CAP1 appears to exhibit species-specific differences compared to its rodent counterparts with respect to its unique peripheral localization, its size, two pI isoforms, and fate during capacitation, which may have implications in its functions.

Induction of Reactive Oxygen Species by Bisphenol A and Abrogation of Bisphenol A-Induced Cell Injury by DJ-1

DJ-1 was first identified as an activated ras-dependent oncogene. DJ-1 is related to male fertility, and its expression in sperm decreases in response to exposure to a number of reproductive toxicants. DJ-1 has been associated with the onset of familial Parkinson's disease (PD) in humans, and has been found to have activity against oxidative damage by eliminating reactive oxygen species (ROS). In this study, we investigated the role of DJ-1 in oxidative stresses by administration of bisphenol A (BPA), which has been reported to induce oxidative stress in rodents, to male mice and cultured cells. In male mice, we found that BPA significantly increased the expression level of DJ-1 in the sperm and brain. In cultured Neuro2a and GC1 cells, we found that BPA induced ROS production and significantly compromised mitochondrial function concomitant with elevated expression and oxidization of DJ-1. DJ-1 was found to maintain the complex I activity against BPA-induced oxidative stress after the localization in mitochondria. The results showed that DJ-1 plays a role in the prevention of mitochondrial injury-induced cell death.

Reproductive and genomic effects in testes from mice exposed to the water disinfectant byproduct bromochloroacetic acid

A byproduct of drinking water disinfection, bromochloroacetic acid (BCA), acts as a reproductive toxicant in rats. To determine if BCA produces similar reproductive toxicity in mice, juvenile and adult C57BL/6 males were exposed to 0, 8, 24, 72 or 216 mg/kg of BCA once daily for 14 days. Five of 12 animals from each dose-group were sacrificed at the end of dosing, and testes, epididymes, and seminal vesicles harvested and weighed. Seven mice from each dose-group (including juvenile-exposed mice, following a 14-week maturation period) were used in a 40-day sequential breeding assay to determine if BCA targets a particular phase of spermatogenesis. No significant effects were observed in mice exposed to BCA as juveniles, and there were no effects on fertility by 14 weeks after dosing. However, effects were observed in adult-exposed mice over the first 10 days after BCA exposure: mean number of litters/male, percentage of litters/female bred, and total number of fetuses/male were all reduced by 72 and 216 mg/kg BCA. These results in adult mice indicate BCA disrupted differentiation of spermatids during dosing and the first 10 days of mating, and are consistent with the spermatid retention and atypical residual bodies observed in animals exposed to 72 and 216 mg/kg BCA. To investigate mechanisms involved, we utilized cDNA microarrays containing 950 testis-expressed genes to profile gene expression from Control and BCA-treated mice. Statistical analyses of microarray results identified 40 well-characterized genes differentially expressed in a dose responsive manner as a result of BCA exposure. Microarray results were supplemented with quantitative real-time PCR and Westerns for several genes and proteins. The 40 genes whose expression was altered by BCA are involved in numerous biological processes including: cell communication and adhesion, cell cycle and cell proliferation, metabolism, signal transduction, stress response, and spermatogenesis and male fertility. Modulated expression of these genes, particularly the 15 expressed in Sertoli cells and spermatids, offers new insights into potential mechanisms of BCA toxicity in the mouse testis.

Serine protease activity, bovine sperm protease, 66 kDa (BSp66), is present in hamster sperm and is involved in sperm–zona interaction

Bovine sperm protease, 66 kDa (BSp66) is a serine protease previously characterized in bovine spermatozoa. Like other proteases, it may be present in sperm from other mammalian species different from bovine, playing a role in the fertilization process. In this study, we looked for BSp66 in hamster spermatozoa using heterologous antibodies against bovine BSp66. An immunoreactive protein was detected by Western blotting in mature and immature sperm. The detected protein had two isoforms similar to the ones reported in bovine sperm. Furthermore, indirect immune detection by fluorescence and electron microscopy assays, showed BSp66 signal at the acrosomal region similar to bovine sperm. As it was determined in bovine sperm, the acrosomal reaction displays the antigen within the acrosomal content. When live hamster sperm was incubated with polyclonal antibody against bovine BSp66 a decrease in the number of sperm bound to zona pellucida in homologous IVF and an impairment of head–head agglutination, were observed. These results suggest that a protease homologous to bovine BSp66 is present in golden hamster spermatozoa, with a conserved molecular mass and cellular location. Moreover, hamster BSp66 is probably involved in zona pellucida recognition.

Dimerization of Parkinson's disease-causing DJ-1 and formation of high molecular weight complexes in human brain

Mutations in the DJ-1 gene have been implicated in the PARK7-linked autosomal recessive form of Parkinson's disease (PD). The molecular properties of DJ-1WT, DJ-1L166P, and a newly identified disease-causing mutant DJ-1M26I were explored after they were transiently expressed in mammalian cells. Treatment of intact, living cells with the chemical crosslinker disuccinimidyl suberate (DSS) revealed that DJ-1WT and mutant DJ-1M26I were present as stable homodimers; DJ-1L166P in particular tended to form high-order complexes as well. In contrast to DJ-1L166P that is quickly degraded by the proteasome, DJ-1M26I was found to be an efficiently expressed and stable variant of DJ-1, suggesting that these mutations have distinct biochemical effects on DJ-1. We further provide evidence that in human brain, under nondenaturing conditions, DJ-1 is present in high molecular weight (HMW) complexes of approximately 250-700 kDa containing parkin, another PD-associated protein.

Identification of the epitope of a monoclonal antibody to DJ-1

Mutations in DJ-1 can cause early onset parkinsonism. Various antibodies have been generated to detect this protein, one of which is a commonly used monoclonal antibody (clone 3E8). Since results of in situ examinations of DJ-1 expression with this antibody have differed from analyses with species-specific antibodies (e.g. rat), it would be useful to know the epitope for this antibody. Using GFP-tagged deletion constructs of human DJ-1, we have localized the epitope region for this antibody to within residues 56-78 of human DJ-1. Mapping this region to the published three-dimensional structure of DJ-1 indicates that this is a solvent-accessible surface epitope. Immunonegativity of E64D mutant DJ-1 with the monoclonal antibody suggests that glutamate 64 of human DJ-1 contributes to the epitope recognized by this antibody. Moreover, the loss of immunoreactivity due to such a small substitution demonstrates the remarkable sensitivity of the monoclonal antibody 3E8 to DJ-1.

BSp66 protease is widespread in the acrosomal region of sperm from several mammalian species

Fertilization in mammals comprises a sequence of events leading to the fusion of sperm and oocyte membranes. Although proteases are known to be involved in this process, their role in fertilization is controversial. There is extensive work on the characterization of proteolytic systems, including serine proteases, which demonstrates that acrosomal proteases can be distinguished among the sperm of different mammalian species on the basis of the gelatin-hydrolyzing activity on SDS-PAGE by the quantity and variety of the enzymes. In this report, we investigated the occurrence and activity of the serine protease BSp66, previously characterized in bovine spermatozoa, in various mammalian sperm. A protein with a molecular mass of 66 kDa cross-reacted with heterologous antibodies against bovine BSp66 when sperm extracts of several mammalian species were analyzed by Western blot. In agreement, proteolytic activity corresponding to the molecular mass of BSp66 was detected by gelatin zymography in all the species analyzed. This protein was located on the acrosomal region of sperm cells by immunofluorescence methods. We concluded that BSp66 is widespread in mammalian sperm, with a conserved location in the acrosomal region.

Immunolocalization of bovine sperm protease BSp120 by light and electron microscopy during capacitation and the acrosome reaction: Its role in in vitro fertilization

Mammalian fertilization involves various steps in which the participation of specific enzymes has been demonstrated by numerous studies. Acrosin is one of the most widely acrosomal protease in mammalian spermatozoa studied, including bovine; however, other proteases have also been described. A new trypsin-like serine protease named bovine serine protease of 120 kDa (BSp120) and its pre-cursor BSp66 (66 kDa) were identified in bovine spermatozoa. Cytological and ultrastructural immunolocalization studies on BSp120 were performed in live and fixed cells. Immunoflorescence assays with specific polyclonal antibodies revealed localization of BSp120 on the sperm head, with a signal homogeneously distributed over the acrosome resembling a horseshoe. After the acrosome reaction, sperm showed a patchy pattern in the acrosomal cap. Immune electron microscopy analysis indicated that BSp120 is located over the head plasma membrane of capacitated spermatozoa and acrosome reacting spermatozoa. To assess BSp120 function in sperm-oocyte interaction, in vitro fertilization studies were conducted. Oocytes were incubated with spermatozoa pre-treated with anti-BSp120, anti-guinea pig acrosin, and anti-BSp120 plus anti-guinea pig acrosin. Pre-treatment of bovine spermatozoa with antibodies towards each protein did not significantly modify fertilization rates. However, when both anti-acrosin and anti-BSp120 antibodies were simultaneously added, there was a significant decrease in the fertilization rate, suggesting that both enzymes may be required for fertilization. Altogether, the results from the present study described the localization of BSp120 over the acrosome of bovine sperm, and suggest its involvement in fertilization.

Reduced anti-oxidative stress activities of DJ-1 mutants found in Parkinson’s disease patients

DJ-1 is a multi-functional protein that plays roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to result in onset of Parkinson's disease. We have previously reported that L166P, a mutant DJ-1 found in Parkinson's disease patients, had no activity to prevent hydrogen peroxide (H2O2)-induced cell death. In this study, we analyzed other mutants of DJ-1 found in Parkinson's disease patients, including M26I, R98Q, and D149A, as well as L166P. We first found that all of the mutants made heterodimers with wild-type DJ-1, while all of the mutants except for L166P made homodimers. We then found that M26I and L166P, both of which are derived from homozygous mutations of the DJ-1 gene, were unstable and that their stabilities were recovered, in part, in the presence of proteasome inhibitor, MG132. NIH3T3 cell lines stably expressing these mutants of DJ-1 showed that cell lines of L166P and C106S, a mutant for protease activity (-) of DJ-1, had no activity to scavenge even endogenously producing reactive oxygen species. These cell lines also showed that all of the mutants had reduced activities to eliminate exogenously added H2O2 and that these activities, except for that of D149A, were parallel to those preventing H2O2-induced cell death.

Familial Parkinson's Disease-associated L166P Mutation Disrupts DJ-1 Protein Folding and Function

Mutations in DJ-1, a protein of unknown function, were recently identified as the cause for an autosomal recessive, early onset form of familial Parkinson's disease. Here we report that DJ-1 is a dimeric protein that exhibits protease activity but no chaperone activity. The protease activity was abolished by mutation of Cys-106 to Ala, suggesting that DJ-1 functions as a cysteine protease. Our studies revealed that the Parkinson's disease-linked L166P mutation impaired the intrinsic folding propensity of DJ-1 protein, resulting in a spontaneously unfolded structure that was incapable of forming a homodimer with itself or a heterodimer with wild-type DJ-1. Correlating with the disruption of DJ-1 structure, the L166P mutation abolished the catalytic function of DJ-1. Furthermore, as a result of protein misfolding, the L166P mutant DJ-1 was selectively polyubiquitinated and rapidly degraded by the proteasome. Together these findings provide insights into the molecular mechanism by which loss-of-function mutations in DJ-1 lead to Parkinson's disease.

DJ-1 has a role in antioxidative stress to prevent cell death

Deletion and point (L166P) mutations of DJ-1 have recently been shown to be responsible for the onset of familial Parkinson's disease (PD, PARK7). The aim of this study was to determine the role of DJ-1 in PD. We first found that DJ-1 eliminated hydrogen peroxide in vitro by oxidizing itself. We then found that DJ-1 knockdown by short interfering RNA rendered SH-SY5Y neuroblastoma cells susceptible to hydrogen peroxide-, MPP+- or 6-hydroxydopamine-induced cell death and that cells harbouring mutant forms of DJ-1, including L166P, became susceptible to death in parallel with the loss of oxidized forms of DJ-1. These results clearly showed that DJ-1 has a role in the antioxidative stress reaction and that mutations of DJ-1 lead to cell death, which is observed in PD.