Interrogating Parkinson's disease associated redox targets: Potential application of CRISPR editing.

Loss of dopaminergic neurons in the substantia nigra is one of the pathogenic hallmarks of Parkinson's disease, yet the underlying molecular mechanisms remain enigmatic. While aberrant redox metabolism strongly associated with iron dysregulation and accumulation of dysfunctional mitochondria is considered as one of the major contributors to neurodegeneration and death of dopaminergic cells, the specific anomalies in the molecular machinery and pathways leading to the PD development and progression have not been identified. The high efficiency and relative simplicity of a new genome editing tool, CRISPR/Cas9, make its applications attractive for deciphering molecular changes driving PD-related impairments of redox metabolism and lipid peroxidation in relation to mishandling of iron, aggregation and oligomerization of alpha-synuclein and mitochondrial injury as well as in mechanisms of mitophagy and programs of regulated cell death (apoptosis and ferroptosis). These insights into the mechanisms of PD pathology may be used for the identification of new targets for therapeutic interventions and innovative approaches to genome editing, including CRISPR/Cas9.

NDPK-D (NM23-H4)-mediated externalization of cardiolipin enables elimination of depolarized mitochondria by mitophagy.

Mitophagy is critical for cell homeostasis. Externalization of the inner mitochondrial membrane phospholipid, cardiolipin (CL), to the surface of the outer mitochondrial membrane (OMM) was identified as a mitophageal signal recognized by the microtubule-associated protein 1 light chain 3. However, the CL-translocating machinery remains unknown. Here we demonstrate that a hexameric intermembrane space protein, NDPK-D (or NM23-H4), binds CL and facilitates its redistribution to the OMM. We found that mitophagy induced by a protonophoric uncoupler, carbonyl cyanide m-chlorophenylhydrazone (CCCP), caused externalization of CL to the surface of mitochondria in murine lung epithelial MLE-12 cells and human cervical adenocarcinoma HeLa cells. RNAi knockdown of endogenous NDPK-D decreased CCCP-induced CL externalization and mitochondrial degradation. A R90D NDPK-D mutant that does not bind CL was inactive in promoting mitophagy. Similarly, rotenone and 6-hydroxydopamine triggered mitophagy in SH-SY5Y cells was also suppressed by knocking down of NDPK-D. In situ proximity ligation assay (PLA) showed that mitophagy-inducing CL-transfer activity of NDPK-D is closely associated with the dynamin-like GTPase OPA1, implicating fission-fusion dynamics in mitophagy regulation.

Impaired mitochondrial biogenesis contributes to depletion of functional mitochondria in chronic MPP+ toxicity: dual roles for ERK1/2.

The regulation of mitochondrial quality has emerged as a central issue in neurodegeneration, diabetes, and cancer. We utilized repeated low-dose applications of the complex I inhibitor 1-methyl-4-phenylpyridinium (MPP(+)) over 2 weeks to study cellular responses to chronic mitochondrial stress. Chronic MPP(+) triggered depletion of functional mitochondria resulting in diminished capacities for aerobic respiration. Inhibiting autophagy/mitophagy only partially restored mitochondrial content. In contrast, inhibiting activation of extracellular signal-regulated protein kinases conferred complete cytoprotection with full restoration of mitochondrial functional and morphological parameters, enhancing spare respiratory capacity in MPP(+) co-treated cells above that of control cells. Reversal of mitochondrial injury occurred when U0126 was added 1 week after MPP(+), implicating enhanced repair mechanisms. Chronic MPP(+) caused a >90% decrease in complex I subunits, along with decreases in complex III and IV subunits. Decreases in respiratory complex subunits were reversed by co-treatment with U0126, ERK1/2 RNAi or transfection of dominant-negative MEK1, but only partially restored by degradation inhibitors. Chronic MPP(+) also suppressed the de novo synthesis of mitochondrial DNA-encoded proteins, accompanied by decreased expression of the mitochondrial transcription factor TFAM. U0126 completely reversed each of these deficits in mitochondrial translation and protein expression. These data indicate a key, limiting role for mitochondrial biogenesis in determining the outcome of injuries associated with elevated mitophagy.

Mitochondrially localized PKA reverses mitochondrial pathology and dysfunction in a cellular model of Parkinson's disease.

Mutations in PTEN-induced kinase 1 (PINK1) are associated with a familial syndrome related to Parkinson's disease (PD). We previously reported that stable neuroblastoma SH-SY5Y cell lines with reduced expression of endogenous PINK1 exhibit mitochondrial fragmentation, increased mitochondria-derived superoxide, induction of compensatory macroautophagy/mitophagy and a low level of ongoing cell death. In this study, we investigated the ability of protein kinase A (PKA) to confer protection in this model, focusing on its subcellular targeting. Either: (1) treatment with pharmacological PKA activators; (2) transient expression of a constitutively active form of mitochondria-targeted PKA; or (3) transient expression of wild-type A kinase anchoring protein 1 (AKAP1), a scaffold that targets endogenous PKA to mitochondria, reversed each of the phenotypes attributed to loss of PINK1 in SH-SY5Y cells, and rescued parameters of mitochondrial respiratory dysfunction. Mitochondrial and lysosomal changes in primary cortical neurons derived from PINK1 knockout mice or subjected to PINK1 RNAi were also reversed by the activation of PKA. PKA phosphorylates the rat dynamin-related protein 1 isoform 1 (Drp1) at serine 656 (homologous to human serine 637), inhibiting its pro-fission function. Mimicking phosphorylation of Drp1 recapitulated many of the protective effects of AKAP1/PKA. These data indicate that redirecting endogenous PKA to mitochondria can compensate for deficiencies in PINK1 function, highlighting the importance of compartmentalized signaling networks in mitochondrial quality control.

Review: autophagy and neurodegeneration: survival at a cost?

Protein aggregation, mitochondrial impairment and oxidative stress are common to multiple neurodegenerative diseases. Homeostasis is regulated by a balanced set of anabolic and catabolic responses, which govern removal and repair of damaged proteins and organelles. Macroautophagy is an evolutionarily conserved pathway for the degradation of long-lived proteins, effete organelles and protein aggregates. Aberrations in macroautophagy have been observed in Alzheimer, Huntington, Parkinson, motor neuron and prion diseases. In this review, we will discuss the divergent roles of macroautophagy in neurodegenerative diseases and suggest a potential regulatory mechanism that could determine cell death or survival outcomes. We also highlight emerging data on neurite morphology and synaptic remodelling that indicate the possibility of detrimental functional trade-offs in the face of neuronal cell survival, particularly if the need for elevated macroautophagy is sustained.

The "pro-apoptotic genies" get out of mitochondria: oxidative lipidomics and redox activity of cytochrome c/cardiolipin complexes.

One of the prominent consequences of the symbiogenic origin of eukaryotic cells is the unique presence of one particular class of phospholipids, cardiolipin (CL), in mitochondria. As the product originated from the evolution of symbiotic bacteria, CL is predominantly confined to the inner mitochondrial membrane in normally functioning cells. Recent findings identified CL and its oxidation products as important participants and signaling molecules in the apoptotic cell death program. Early in apoptosis, massive membrane translocations of CL take place resulting in its appearance in the outer mitochondrial membrane. Consequently, significant amounts of CL become available for the interactions with cyt c, one of the major proteins of the intermembrane space. Binding of CL with cytochrome c (cyt c) yields the cyt c/CL complex that acts as a potent CL-specific peroxidase and generates CL hydroperoxides. In this review, we discuss the catalytic mechanisms of CL oxidation by the peroxidase activity of cyt c as well as the role of oxidized CL (CLox) in the release of pro-apoptotic factors from mitochondria into the cytosol. Potential implications of cyt c/CL peroxidase intracellular complexes in disease conditions (cancer, neurodegeneration) are also considered. The discovery of the new role of cyt c/CL complexes in early mitochondrial apoptosis offers interesting opportunities for new targets in drug discovery programs. Finally, exit of cyt c from damaged and/or dying (apoptotic) cells into extracellular compartments and its accumulation in biofluids is discussed in lieu of the formation of its peroxidase complexes with negatively charged lipids and their significance in the development of systemic oxidative stress in circulation.

The aetiology in paediatric aphakic glaucoma.

PURPOSE: To investigate the causes of glaucoma in children following removal of cataracts. METHODS: In total, 24 patients (37 eyes) with uncomplicated congenital cataracts who developed glaucoma following cataract removal were studied retrospectively. Cataract morphology, surgical technique, postoperative complications, time to glaucoma onset, gonioscopic findings, the presence of microcornea, and the histopathologic characteristics of the filtration angle in one case were the studied parameters. RESULTS: We found a bimodal onset of glaucoma. Early-onset glaucoma occurred at a mean age of 6 months in 15 eyes and delayed-onset glaucoma at a mean age of 12 years in 22 eyes. Early-onset glaucoma was significantly (P=0.018) more likely to be due to angle closure. With delayed-onset glaucoma, the filtration angle is open in 86% of eyes and significantly (P=0.006) more eyes in the delayed-onset group had microcornea. CONCLUSIONS: Performing cataract surgery very early in life in microphthalmic eyes and leaving residual lens material increases the risk for glaucoma. We recommend a prophylactic iridectomy in eyes at risk for pupillary block. Eyes with delayed-onset glaucoma have open filtration angles but with findings consistent with incomplete development of filtration structures. Early age at cataract extraction and microcornea are risk factors for delayed-onset glaucoma.

Altered expression of extracellular superoxide dismutase in mouse lung after bleomycin treatment.

The antioxidant enzyme extracellular superoxide dismutase (EC-SOD) is highly expressed in the extracellular matrix of lung tissue and is believed to protect the lung from oxidative damage that results in diseases such as pulmonary fibrosis. This study tests the hypothesis that proteolytic removal of the heparin-binding domain of EC-SOD results in clearance of the enzyme from the extracellular matrix of pulmonary tissues and leads to a loss of antioxidant protection. Using a polyclonal antibody to mouse EC-SOD, the immunodistribution of EC-SOD in normal and bleomycin-injured lungs was examined. EC-SOD labeling was strong in the matrix of vessels, airways, and alveolar surfaces and septa in control lungs. At 2 d post-treatment, a slight increase in EC-SOD staining was evident. In contrast, lungs examined 4 or 7 d post-treatment, showed an apparent loss of EC-SOD from the matrix and surface of alveolar septa. Notably, at 7 d post-treatment, the truncated form of EC-SOD was found in the bronchoalveolar lavage fluid of bleomycin-treated mice, suggesting that EC-SOD is being removed from the extracellular matrix through proteolysis. However, loss of EC-SOD through proteolysis did not correlate with a decrease in overall pulmonary EC-SOD activity. The negligible effect on EC-SOD activity may reflect the large influx of intensely staining inflammatory cells at day 7. These results indicate that injuries leading to pulmonary fibrosis have a significant effect on EC-SOD distribution due to proteolytic removal of the heparin-binding domain and may be important in enhancing pulmonary injuries by altering the oxidant/antioxidant balance in alveolar interstitial spaces.

Epidermoid cyst of the thoracic spine: case history.

Epidermoid cysts of the spinal cord are very rare tumors. We report a 31 year-old female who presented with a 5 months history of progressive lower extremity weakness and spasticity. Magnetic resonance imaging of the thoracic spine revealed a 2 cm intradural, extramedullary mass at the T4-5 level. A T4 and T5 osteoplastic laminotomy with complete removal of the intradural mass was performed. Intraoperative and final histological examination revealed an epidermoid cyst. Epidermoid cysts must be a consideration for intradural, extramedullary lesions of the spinal cord. Complete surgical resection offers the patient an opportunity for good neurologic outcome.

Some specific human leukocyte antigen (HLA)-DR/DQ haplotypes are more important than individual HLA-DR and -DQ phenotypes for the development of mucocutaneous type of Behçet's disease and for disease shift from recurrent aphthous stomatitis to mucocutaneous type of Behçet's disease.

The phenotype and haplotype frequencies of human leukocyte antigens (HLA)-DR and -DQ in 32 Chinese patients with the mucocutaneous (MC) type of Behçet's disease (BD) were calculated and compared with those in 310 healthy control Chinese and with those in 80 Chinese patients with recurrent aphthous stomatitis (RAS). We found that the phenotype frequency of HLA-DRw8 [corrected P (Pc)<0.005] and the haplotype frequencies of HLA-DRw8/DQw1 (Pc<0.005), -DRw8/DQw5(w1) (Pc<0.0005), -DRw12(5)/DQw1 (Pc<0.005), -DRw12(5)/DQw6(w1) (Pc< 0.0005), and -DRw52/DQw1 (Pc<0.005) in patients with the MC type of BD were significantly greater than those in healthy control subjects. This finding suggests that individual Chinese with HLA-DRw8 antigen and HLA-DRw8/DQw1, -DRw8/DQw5(w1), -DRw12(5)/DQw1, -DRw12(5)/DQw6(w1) and -DRw52/DQw1 haplotypes are more likely to have the MC type of BD. Furthermore, the relative risks (RRs) of HLA-DRw8/DQw1 (5.6), -DRw8/ DQw5 (w1) (10.0), and -DRw12(5)/DQw6(w1) (14.4) haplotypes in patients with the MC type of BD were equal to or higher than the RR of HLA-DRw8 phenotype (5.6), suggesting that some of the HLA-DR/DQ haplotypes may play more important roles than the individual HLA-DR and -DQ phenotypes for the development of the MC type of BD. The phenotype frequencies of HLA-DR5 (Pc<0.01), -DRw8 (Pc<0.005) and -DQw1 (Pc<0.05) as well as the haplotype frequencies of HLA-DR5/DQw1 (P<0.005) and -DRw8/DQw1 (Pc<0.00005) in patients with the MC type of BD were significantly higher than those in patients with RAS. Moreover, the RRs of HLA-DR5/DQw1 (29.1) and -DRw8/DQw1 (47.4) haplotypes were greater than the RRs of HLA-DR5 (10.4), -DRw8 (23.4) and -DQw1 (4.0) antigens. These results suggest that some specific HLA-DR/DQ haplotypes may be more important than the individual HLA-DR and -DQ phenotypes in the disease shift from RAS to the MC type of BD.

Sustained extracellular signal-regulated kinase activation by 6-hydroxydopamine: implications for Parkinson's disease.

Although the toxin 6-hydroxydopamine (6-OHDA) is utilized extensively in animal models of Parkinson's disease, the underlying mechanism of its toxic effects on dopaminergic neurons is not completely understood. We examined the effects of 6-OHDA on the CNS-derived tyrosine hydroxylase expressing B65 cell line, with particular attention to the regulation of the extracellular signal-regulated protein kinases (ERK). 6-OHDA elicited a dose-dependent cytotoxicity in B65 cells. Toxic doses of 6-OHDA also elicited a biphasic pattern of ERK phosphorylation with a prominent sustained phase, a pattern that differed from that observed with hydrogen peroxide (H(2)O(2)) treatment. 6-OHDA-elicited ERK phosphorylation was blocked by PD98059, an inhibitor of the upstream mitogen activated protein kinase kinase (MEK) that phosphorylates and activates ERK. PD98059 also conferred protection against 6-OHDA cytotoxicity, but did not affect H(2)O(2) toxicity in B65 cells. These results suggest that ERK activation plays a direct mechanistic role in 6-OHDA toxicity, rather than representing a protective compensatory response, and raise the possibility that abnormal patterns of ERK activation may contribute to dopaminergic neuronal cell death.

Impairment of long-term potentiation and associative memory in mice that overexpress extracellular superoxide dismutase.

Reactive oxygen species, including superoxide, generally are considered neurotoxic molecules whose effects can be alleviated by antioxidants. Different from this view, we show that scavenging of superoxide with an antioxidant enzyme is associated with deficits in hippocampal long-term potentiation (LTP), a putative neural substrate of memory, and hippocampal-mediated memory function. Using transgenic mice that overexpress extracellular superoxide dismutase (EC-SOD), a superoxide scavenger, we found that LTP was impaired in hippocampal area CA1 despite normal LTP in area CA3. The LTP impairment in area CA1 could be reversed by inhibition of EC-SOD. In addition, we found that EC-SOD transgenic mice exhibited impaired long-term memory of fear conditioning to contextual cues despite exhibiting normal short-term memory of the conditioning experience. These findings strongly suggest that superoxide, rather than being considered exclusively a neurotoxic molecule, should also be considered a signaling molecule necessary for normal neuronal function.

Expression of interleukin-2 receptor by activated peripheral blood lymphocytes upregulated by the plasma level of interleukin-2 in patients with recurrent aphthous ulcers.

This study used flow cytometry to determine the peripheral blood lymphocyte subsets and a sandwich enzyme immunoassay to measure the plasma levels of interleukin-2 (IL-2) and soluble IL-2 receptor (sIL-2R) in 34 patients in different stages of recurrent aphthous ulcers (RAU) and in 32 age/sex-matched normal control subjects. In the exacerbation stage of RAU, a significant increase in the percentages of CD3+ (p < 0.001), CD4+ (p < 0.001), CD4+ IL-2R+ (p < 0.001), CD8+ IL-2R+ (p < 0.01) and IL-2R+ cells (p < 0.001), in the CD4+/CD8+ (p < 0.01) and CD4+/CD3+ CD8+ ratios (p < 0.01), and in the plasma level of IL-2 (p < 0.001) was found in the patients as compared with the levels in the normal control subjects. However, in the post-exacerbation stage of RAU, there was a significant decrease in the percentage of CD4+ cells (p < 0.05) and in the CD4+/CD8+ (p < 0.01) and CD4+/CD3+ CD8+ ratios (p < 0.001), as well as a significant increase in CD8+ cells (p < 0.001) in the patients, as compared with the levels in the normal control subjects. Because the CD4+, CD4+ IL-2R+ and CD8+ IL-2R+ cell counts and the plasma level of IL-2 increased simultaneously in the patients in the exacerbation stage of RAU, we suggest that the markedly increased plasma level of IL-2 may have been secreted by the increased number of activated CD4+ cells, and that the expression of IL-2R by activated peripheral blood lymphocytes was upregulated by the plasma level of IL-2 in patients with RAU. In addition, the increase and then decrease of the CD4+/CD8+ ratio in the RAU patients and the increased number of CD4+ IL-2R+ and CD8+ IL-2R+ activated T cells in the RAU patients support the role of cell-mediated cytotoxicity in the immunopathogenesis of RAU.

Ubiquitin immunochemistry as a diagnostic aid for community pathologists evaluating patients who have dementia.

Alzheimer's disease is the most common cause of dementia It is associated with genetic risk factors and at least three autosomal dominant mutations. Community pathologists are frequently asked by families to evaluate autopsy material for Alzheimer's disease. Neuropathologic diagnosis is based on technically difficult silver impregnation stains that may not be readily available to community-based pathologists. Because immunohistochemical techniques are more widely accessible, we evaluated the practical utility of using a single immunohistochemical stain for diagnosing Alzheimer's disease. The ubiquitin antigen was selected because of its presence in morphologically distinct deposits characteristic of several neurodegenerative diseases. Paraffin blocks were obtained from the Bryan Alzheimer's Disease Research Center Brain Bank, a repository of approximately 900 brains. Tissues from 16 individuals who exhibited the entire range of Alzheimer's-type neuropathology were selected. Ubiquitin immunostains, evaluated blindly and independently by four pathologists ranging from first-year resident trainee to experienced neuropathologist, reliably stained both neuritic plaques and neurofibrillary tangles essential for diagnosing and staging Alzheimer's disease. Nondemented controls with early Alzheimer's-type changes were easily distinguished from cases of definitive Alzheimer's disease. The stains also highlighted characteristic inclusions of Parkinson's disease or Lewy body dementia Ubiquitin immunohistochemistry is a reliable, reproducible, and readily available diagnostic aid for distinguishing Alzheimer's disease from other causes of dementia.

Electron microscopic diagnosis of human flavivirus encephalitis: use of confocal microscopy as an aid.

The distinction between intracranial viral infections and inflammatory conditions requiring immunosuppression is important. Although specific laboratory reagents are readily available for some viruses, diagnosis of arbovirus infection is more difficult. Transmission electron microscopy (TEM) theoretically allows identification of viral particles independent of reagent availability, but it has limited sensitivity. We report two cases of human flavivirus encephalitis diagnosed by TEM. Laser scanning confocal microscopy (LSCM) was used in one case to survey unembedded tissue slices for focal abnormalities, from which fragments smaller than 1 mm2 were excised for epoxy embedding. This facilitated TEM identification of intracytoplasmic, budding, 35-40 nm spherical virus particles, confirmed by serology as St. Louis encephalitis. In contrast to mosquitoes and newborn mice, in which high viral loads are associated with minimal tissue responses, these biopsies showed florid angiodestructive inflammation and microgliosis, with rare virions in necrotic perivascular cells and astrocytes. To our knowledge, this represents the first ultrastructural study of St. Louis encephalitis in humans, indicating the potential value of LSCM-aided TEM.

Gliomatosis cerebri: cytologic and autopsy findings in a case involving the entire neuraxis.

We describe the case of a 7-year-old girl who was clinically diagnosed as having a pontine glioma based on magnetic resonance imaging studies. Neoplastic cells were identified upon cytologic examination of cerebrospinal fluid. Autopsy studies revealed an anaplastic astrocytoma (WHO grade III) diffusely infiltrating the cerebral hemispheres, brain stem, cerebellum, leptomeninges, and spinal cord to the level of the conus medullaris. The Ki-67 labeling index focally approached 30%. Although many of the neoplastic cells displayed elongated twisted nuclei reminiscent of microglia, these cells stained intensely for glial fibrillary acidic protein, supporting an astrocytic origin. Unusual features of this case of gliomatosis cerebri include involvement of the entire central neuraxis, correlation with pre-mortem lumbar puncture cytology, and a markedly elevated Ki-67 labeling index.

December 1998--16 year old female with headaches, lethargy and a sellar/suprasellar mass.

A 16 year female with a history of developmental delay and shunted hydrocephalus presented with two months of progressive headaches, lethargy and visual disturbances. An MRI of the brain revealed a sellar and suprasellar cystic mass which was absent on a previous MRI six years earlier. The pre-operative clinical diagnosis was pituitary adenoma vs. craniopharyngioma. Histologically, the fibrous wall of the ciliated epithelial-lined cyst was thickened by non-caseating granulomatous inflammation, hemorrhage, hemosiderin, and cholesterol clefts, consistent with cyst rupture. Rathke's cleft cysts are uncommon symptomatic lesions in young people, and must be distinguished from craniopharyngioma.

Sympathetic ganglionic blockade masks beneficial effect of isoflurane on histologic outcome from near-complete forebrain ischemia in the rat.

BACKGROUND: Isoflurane-anesthetized rats have better outcome from global cerebral ischemia than rats anesthetized with fentanyl and nitrous oxide. The authors wanted to determine whether circulating catecholamine concentrations depend on the anesthetic agent and whether sympathetic ganglionic blockade affects anesthetic-mediated differences in outcome from near-complete forebrain ischemia. METHODS: For two different experiments, normothermic Sprague-Dawley rats that had fasted were assigned to one of four groups and subjected to 10 min of 30 mm Hg mean arterial pressure and bilateral carotid occlusion. Rats were anesthetized with 1.4% isoflurane or fentanyl (25 microg x kg(-1) x h(-1)) and 70% nitrous oxide, with or without preischemic trimethaphan (2.5 mg given intravenously). In experiment 1, arterial plasma catecholamine concentrations were measured before, at 2 and 8 min during, and after ischemia (n = 5-8). In experiment 2, animals (n = 15) underwent histologic analysis 5 days after ischemia. RESULTS: In experiment 1, intraischemic increases in plasma norepinephrine and epinephrine levels were 28 and 12 times greater in the fentanyl-nitrous oxide group than in the isoflurane group (P<0.01). Trimethaphan blocked all changes in plasma catecholamine concentrations (P<0.02). In experiment 2, isoflurane reduced the mean +/- SD percentage of dead hippocampal CA1 neurons compared with fentanyl-nitrous oxide (43+/-22% vs. 87+/-10%; P<0.001). Trimethaphan abolished the beneficial effects of isoflurane (91+/-6%; P<0.001). Similar observations were made in the cortex. CONCLUSIONS: Isoflurane attenuated the peripheral sympathetic response to ischemia and improved histologic outcome compared with fentanyl and nitrous oxide. This outcome benefit was reversed by sympathetic ganglionic blockade. The beneficial effects of isoflurane may result from a neuroprotective influence of an intermediate sympathetic response that is abolished by trimethaphan.