DJ-1 deficiency in astrocytes selectively enhances mitochondrial Complex I inhibitor-induced neurotoxicity.

Parkinson's disease (PD) brains show evidence of mitochondrial respiratory Complex I deficiency, oxidative stress, and neuronal death. Complex I-inhibiting neurotoxins, such as the pesticide rotenone, cause neuronal death and parkinsonism in animal models. We have previously shown that DJ-1 over-expression in astrocytes augments their capacity to protect neurons against rotenone, that DJ-1 knock-down impairs astrocyte-mediated neuroprotection against rotenone, and that each process involves astrocyte-released factors. To further investigate the mechanism behind these findings, we developed a high-throughput, plate-based bioassay that can be used to assess how genetic manipulations in astrocytes affect their ability to protect co-cultured neurons. We used this bioassay to show that DJ-1 deficiency-induced impairments in astrocyte-mediated neuroprotection occur solely in the presence of pesticides that inhibit Complex I (rotenone, pyridaben, fenazaquin, and fenpyroximate); not with agents that inhibit Complexes II-V, that primarily induce oxidative stress, or that inhibit the proteasome. This is a potentially PD-relevant finding because pesticide exposure is epidemiologically-linked with an increased risk for PD. Further investigations into our model suggested that astrocytic GSH and heme oxygenase-1 antioxidant systems are not central to the neuroprotective mechanism.

DJ-1 expression in glioblastomas shows positive correlation with p53 expression and negative correlation with epidermal growth factor receptor amplification.

DJ-1, a protein that promotes the action of multiple anti-apoptotic/pro-survival pathways, is expressed prominently in human reactive astrocytes and in many human cancers. Glioblastomas (GBMs) are the most common adult primary brain tumor, and most show either abnormalities in p53 or epidermal growth factor receptor (EGFR) amplification, but not both. In this retrospective study of 40 surgically resected GBMs, we compared the immunohistochemical intensity of DJ-1 expression (based on blinded scoring by independent examiners) to these and other molecular factors associated with GBM oncogenesis. We report here that: (i) most of the GBMs that we studied expressed DJ-1 protein at significant levels, and typically in a cytoplasmic, non-nuclear fashion; (ii) DJ-1 staining intensity varied directly with strong nuclear p53 expression (assessed by immunostaining); and (iii) DJ-1 staining intensity varied inversely with EGFR amplification (assessed by fluorescent in situ hybridization). Since the anti-apoptotic/pro-survival actions of DJ-1 have been clearly linked in in vitro systems to p53 and receptor tyrosine kinase (i.e. EGFR) pathways that are hypothesized to be critical to GBM genesis, these observations indicate that DJ-1 expression may play a role in the biology of some types of GBMs. Therefore, given the new associations presented here between DJ-1, p53 and EGFR amplification in GBMs, future investigations of these tumors should include an analysis of DJ-1 to determine whether its expression pattern is important for tumor progression, prognosis and responsiveness to therapy.

DJ-1 knock-down in astrocytes impairs astrocyte-mediated neuroprotection against rotenone.

Mutations that eliminate DJ-1 expression cause a familial form of Parkinson's disease (PD). In sporadic PD, and many other neurodegenerative diseases, reactive astrocytes over-express DJ-1 whereas neurons maintain its expression at non-disease levels. Since DJ-1 has neuroprotective properties, and since astrocytes are known to support and protect neurons, DJ-1 over-expression in reactive astrocytes may reflect an attempt by these cells to protect themselves and surrounding neurons against disease progression. We used neuron-astrocyte contact and non-contact co-cultures to show that DJ-1 knock-down in astrocytes impaired their neuroprotective capacity, relative to wild-type astrocytes, against the neurotoxin rotenone. Conversely, DJ-1 over-expression in astrocytes augmented their neuroprotective capacity. Experiments using astrocyte conditioned media on neuron-only cultures suggested that astrocyte-released, soluble factors were involved in the DJ-1-dependent, astrocyte-mediated neuroprotective mechanism. Our findings support the developing view that astrocytic dysfunction, in addition to neuronal dysfunction, may contribute to the progression of a variety of neurodegenerative disorders.

DJ-1 immunoreactivity in human brain astrocytes is dependent on infarct presence and infarct age.

DJ-1 is a protein with anti-oxidative stress and anti-apoptotic properties that is abundantly expressed in reactive CNS astrocytes in chronic neurodegenerative disorders such as Parkinson's disease (PD), Alzheimer's disease (AD), and Pick's disease. Genetic mutations which eliminate DJ-1 expression in humans are sufficient to produce an early-onset form of familial PD, PARK7, suggesting that DJ-1 is a critical component of the neuroprotective arsenal of the brain. Previous studies in parkinsonism/dementia brain tissues have revealed that reactive astrocytes within and surrounding incidentally identified infarcts were often robustly immunoreactive for DJ-1, especially if the infarcts showed histological features consistent with older age. Given this, we sought to evaluate astrocytic DJ-1 expression in human stroke more extensively, and with a particular emphasis on determining whether immunohistochemical DJ-1 expression in astrocytes correlates with histological infarct age. The studies presented here show that DJ-1 is abundantly expressed in reactive infarct region astrocytes in both gray and white matter, that subacute and chronic infarct region astrocytes are much more robustly DJ-1+ than are acute infarct and non-infarct region astrocytes, and that DJ-1 staining intensity in astrocytes generally correlates with that of the reactive astrocyte marker GFAP. Confocal imaging of DJ-1 and GFAP dual-labelled human brain sections were used to confirm the localization to and expression of DJ-1 in astrocytes. Neuronal DJ-1 staining was minimal under all infarct and non-infarct conditions. Our data support the conclusion that the major cellular DJ-1 response to stroke in the human brain is astrocytic, and that there is a temporal correlation between DJ-1 expression in these cells and advanced infarct age.

Three-dimensional orientation tuning in macaque area V4.

Tuning for the orientation of elongated, linear image elements (edges, bars, gratings), first discovered by Hubel and Wiesel, is considered a key feature of visual processing in the brain. It has been studied extensively in two dimensions (2D) using frontoparallel stimuli, but in real life most lines, edges and contours are slanted with respect to the viewer. Here we report that neurons in macaque area V4, an intermediate stage in the ventral (object-related) pathway of visual cortex, were tuned for 3D orientation--that is,for specific slants as well as for 2D orientation. The tuning for 3D orientation was consistent across depth position (binocular disparity) and position within the 2D classical receptive field. The existence of 3D orientation signals in the ventral pathway suggests that the brain may use such information to interpret 3D shape.

Zebrafish DJ-1 is evolutionarily conserved and expressed in dopaminergic neurons.

Loss-of-function mutations in the human PARK7 gene, encoding DJ-1, are a rare cause of autosomal recessive Parkinson's disease (ARPD). To facilitate generation of a novel vertebrate model, in which to examine the biochemical functions of DJ-1 in vivo, we cloned and characterized the zebrafish orthologue of DJ-1 (zDJ-1). The 0.95 kb zDJ-1 mRNA is expressed in adult zebrafish brain, muscle and gut, and in the embryo from 24 h post-fertilization. The zDJ-1 transcript encodes a 19.8 kDa, 189 amino acid protein, which is 83% identical to human DJ-1. Residues thought to be functionally important sites of post-translational modification in human DJ-1, and critical positions affected by pathogenic missense mutations in ARPD patients, are conserved in zDJ-1. The 14 kb zDJ-1 gene contains six exons and is located on zebrafish chromosome 8; the structure of the gene is highly homologous to human DJ-1, except that there are no alternatively spliced non-coding 5' exons. The single zDJ-1 first exon shows 5' end heterogeneity, reflecting multiple transcription start sites. In the adult zebrafish brain, zDJ-1 immunoreactivity was prominent in the cytoplasm of most neurons, and in the neuropil, but was less evident within white matter tracts, consistent with neuronal somatic and dendritic localization. Dopaminergic neurons in each of the major forebrain and diencephalic TH-positive cell groups expressed zDJ-1. These studies show that zDJ-1 is very similar to human DJ-1 and delineate essential resources, allowing further examination of the function and regulation of DJ-1, using the zebrafish as a model.

Single-cell molecular biology: implications for diagnosis and treatment of neurologic disease.

The continued discovery of basic pathologic mechanisms underlying neuropsychiatric illnesses will be critical to the development of improved diagnostic tests and more targeted therapeutic strategies. Molecular biological methods capable of evaluating gene expression at the single-cell level have great potential for advancing our knowledge of these processes. This review describes two techniques that are providing new insights into the intracellular regulation of ribonucleic acid trafficking and processing. These technologies promise to accelerate our understanding of both normal and abnormal molecular processes within neurons, and they have the potential for direct application to the study of human neurologic disease.

Analysis of novel tumor markers in pancreatic and biliary carcinomas using tissue microarrays.

Using global gene expression analyses, multiple novel tumor markers overexpressed in infiltrating ductal adenocarcinomas of the pancreas have recently been identified. However, the expression of these markers in morphologically similar adenocarcinomas of the biliary tree has not been investigated. The purpose of the present study was 3-fold. First, we used 8 markers that have been shown to be overexpressed in whole tissue sections of pancreatic adenocarcinomas to validate tissue microarrays (TMAs) created from a series of pancreatic adenocarcinomas (n=68). The labeling patterns of 6 epithelial markers (fascin, mucin 4, 14-3-3sigma, prostate stem cell antigen, topoisomerase IIalpha, and cdc2/p34) were concordant with previously published studies on whole tissue sections, yet required far fewer slides and reagents. Mesothelin, an epithelial marker, and heat shock protein 47, a marker of peritumoral desmoplasia, showed lower levels of expression in the TMAs when compared with whole tissue sections. Second, we examined the previously unknown expression of the same 8 novel tumor proteins in cancers of the biliary tree by using TMAs created from a series of intrahepatic cholangiocarcinomas, gallbladder adenocarcinomas, and adenocarcinomas of the distal common bile duct (n=38). Each of the 8 markers was overexpressed in the biliary cancers, ranging from 14% demonstrating at least focal labeling with prostate stem cell antigen to 100% labeling with cdc2/p34. Most of the markers showed lower frequencies of expression in the biliary tract carcinomas in comparison to the pancreatic adenocarcinomas. In addition, expression patterns varied with location in the biliary system (intrahepatic versus gallbladder versus distal common bile duct). These differences were statistically significant (P<0.05) for mesothelin, mucin 4, and heat shock protein 47. Finally, the expression of selected markers in neoplastic progression of gallbladder cancer was examined. Two markers, fascin and mesothelin, showed up-regulation of expression with transition from carcinoma in situ to invasive adenocarcinoma, implicating a role for these markers in neoplastic progression. The results of this study indicate that TMA technology provides valid and cost-effective means to screen large numbers of novel tumor markers, even in tumors such as pancreatic and biliary adenocarcinomas that characteristically have abundant desmoplastic stroma. In addition, novel tumor markers of pancreatic adenocarcinomas show similar, yet not identical, expression patterns in biliary carcinomas. Therefore, these markers are potentially useful in developing diagnostic tests and treatment paradigms for tumors involving the biliary system.

Impact of liquid-based gynecologic cytology on an HIV-positive population.

OBJECTIVE: To examine the imprint of liquid-based technologies for cervicovaginal cytology on HIV-positive women, who are at high risk for cervical intraepithelial neoplasia. STUDY DESIGN: We performed a retrospective search of the cytopathology files of Johns Hopkins Hospital for the cervicovaginal cytology of HIV-positive women to examine the effect of liquid-based technology on this population. RESULTS: Significant intraepithelial lesions (SILs) (low grade SIL or greater) were identified in 24% of the conventional smears and 23% of the liquid-based cytology. Atypical squamous cells of undetermined significance (ASCUS)/atypical glandular cells of undetermined significance was diagnosed in 15% of the conventional smears and 9% of the liquid-based preparations (P = .02). In patients with ASCUS diagnoses and tissue follow-up within 7 months, significant SILs were identified in 29% with conventional smears and in 65% with liquid-based cytology. CONCLUSION: There was no statistically significant difference in the rate of SILs between conventional smears and liquid-based cervicovaginal preparations in HIV-positive women. The diagnosis of ASCUS on liquid-based cytology may have an increased likelihood of representing a significant SIL in comparison to conventional smears. For the high-risk, HIV-positive population, immediate colposcopy and biopsy may be warranted following ASCUS diagnoses on liquid-based cytology.

DJ-1 expression modulates astrocyte-mediated protection against neuronal oxidative stress.

DJ-1 deficiency is a cause of genetic Parkinson's disease (PARK7 PD). In sporadic Parkinson's disease (PD), however, DJ-1 is abundantly expressed in reactive astrocytes. This may represent a compensatory protective response. In initial support of this hypothesis, we have shown in vitro that DJ-1-overexpressing astrocytes protect neurons against rotenone-induced death. Rotenone, a pesticide linked to increased PD risk, can stimulate oxidative stress. This process is implicated in PD pathogenesis. Since DJ-1 can enhance antioxidant systems, we hypothesized that augmenting its expression in astrocytes would protect cocultured neurons against oxidative stress. We report here that DJ-1-overexpressing astrocytes were significantly more protective against rotenone-induced neuronal thiol oxidation than wild-type astrocytes in neuron-astrocyte cocultures. DJ-1-knockdown astrocytes, on the other hand, were significantly impaired in their capacity to protect neurons against thiol oxidation. Each of these findings was replicated using astrocyte-conditioned media on neuron-enriched cultures. Thus, DJ-1-modulated, astrocyte-released soluble factors must be involved in the mechanism. This is the first demonstration that the manipulation of a PD-causing gene in astrocytes affects their ability to protect neurons against oxidative stress.

Quantitative characterization of disparity tuning in ventral pathway area V4.

We performed a quantitative characterization of binocular disparity-tuning functions in the ventral (object-processing) pathway of the macaque visual cortex. We measured responses of 452 area V4 neurons to stimuli with disparities ranging from -1.0 to +1.0 degrees. Asymmetric Gaussian functions fit the raw data best (median R = 0.90), capturing both the modal components (local peaks in the -1.0 to +1.0 degrees range) and the monotonic components (linear or sigmoidal dependency on disparity) of the tuning patterns. Values derived from the asymmetric Gaussian fits were used to characterize neurons on a modal x monotonic tuning domain. Points along the modal tuning axis correspond to classic tuned excitatory and inhibitory patterns; points along the monotonic axis correspond to classic near and far patterns. The distribution on this domain was continuous, with the majority of neurons exhibiting a mixed modal/monotonic tuning pattern. The distribution in the modal dimension was shifted toward excitatory patterns, consistent with previous results in other areas. The distribution in the monotonic dimension was shifted toward tuning for crossed disparities (corresponding to stimuli nearer than the fixation plane). This could reflect a perceptual emphasis on objects or object parts closer to the observer. We also found that disparity-tuning strength was positively correlated with orientation-tuning strength and color-tuning strength, and negatively correlated with receptive field eccentricity.

Methodological considerations regarding single-cell gene expression profiling for brain injury.

Genomic microarrays are rapidly becoming ubiquitous throughout a wide variety of biological disciplines. As their use has grown during the past few years, many important discoveries have been made in the fields of central nervous system (CNS) injury and disease using this emerging technology. In addition, single-cell mRNA amplification techniques are now being used along with microarrays to overcome many of the difficulties associated with the cellular heterogeneity of the brain. This development has extended the utility of gene expression profiling and has provided researchers with exciting new insights into the neuropathology of CNS injury and disease at a molecular and cellular level. New methodological, standardization, and statistical techniques are currently being developed to improve the reproducibility of microarrays and facilitate the analysis of large amounts of data. In this review, we will discuss the application of these techniques to experimental, clinically relevant models of traumatic brain injury.

Co-occurrence of Parkinson's disease with progressive supranuclear palsy.

Parkinson's disease (PD) and progressive supranuclear palsy (PSP) are distinct neurodegenerative disorders. We describe an 81-year-old woman with 3 years of progressive gait unsteadiness, frequent falls, and mild cognitive dysfunction, all considered clinically to be an early fronto-temporal neurodegenerative disorder. She died of an acute myocardial infarction. Examination of her brain revealed alpha-synuclein- and tau-positive inclusions diagnostic of PD and PSP. Immunoelectron microscopy and Western blot analysis confirmed combined PD/PSP. This case provides strategies for the reliable molecular validation of concomitant PD and PSP, and demonstrates the utility of these techniques in patients with atypical clinical presentations.

DJ-1 colocalizes with tau inclusions: a link between parkinsonism and dementia.

Two novel mutations recently have been identified in the DJ-1 gene that cause a new form of autosomal recessive, early-onset parkinsonism. Because the pathological role of this protein is unknown, we examined the issue here and report the colocalization of DJ-1 protein within a subset of pathological tau inclusions in a diverse group of neurodegenerative disorders known as tauopathies. Our study extends the view that different neurodegenerative diseases may have similar pathological mechanisms, and that these processes likely include DJ-1.