␣-Synuclein (␣-Syn) is enriched in nerve terminals. Two mutations in the ␣-Syn gene (Ala533 Thr and Ala303 Pro) occur in autosomal dominant familial Parkinson's disease. Mice overexpressing the human A53T mutant ␣-Syn develop a severe movement disorder, paralysis, and synucleinopathy, but the mechanisms are not understood. We examined whether transgenic mice expressing human wild-type or familial Parkinson's disease-linked A53T or A30P mutant ␣-syn develop neuronal degeneration and cell death. Mutant mice were examined at early-to mid-stage disease and at near end-stage disease. Age-matched nontransgenic littermates were controls. In A53T mice, neurons in brainstem and spinal cord exhibited large axonal swellings, somal chromatolytic changes, and nuclear condensation. Spheroid eosinophilic Lewy body-like inclusions were present in the cytoplasm of cortical neurons and spinal motor neurons. These inclusions contained human ␣-syn and nitrated synuclein. Motor neurons were depleted (ϳ75%) in A53T mice but were affected less in A30P mice. Axonal degeneration was present in many regions. Electron microscopy confirmed the cell and axonal degeneration and revealed cytoplasmic inclusions in dendrites and axons. Some inclusions were degenerating mitochondria and were positive for human ␣-syn. Mitochondrial complex IV and V proteins were at control levels, but complex IV activity was reduced significantly in spinal cord. Subsets of neurons in neocortex, brainstem, and spinal cord ventral horn were positive for terminal deoxynucleotidyl transferasemediated biotinylated UTP nick end labeling, cleaved caspase-3, and p53. Mitochondria in neurons had terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling-positive matrices and p53 at the outer membrane. Thus, A53T mutant mice develop intraneuronal inclusions, mitochondrial DNA damage and degeneration, and apoptotic-like death of neocortical, brainstem, and motor neurons.

The mechanisms of human mutant superoxide dismutase-1 (mSOD1) toxicity to motor neurons (MNs) are unresolved. We show that MNs in G93A-mSOD1 transgenic mice undergo slow degeneration lacking similarity to apoptosis structurally and biochemically. It is characterized by somal and mitochondrial swelling and formation of DNA single-strand breaks prior to double-strand breaks occurring in nuclear and mitochondrial DNA. p53 and p73 are activated in degenerating MNs, but without nuclear import. The MN death is independent of activation of caspases-1, -3, and -8 or apoptosis-inducing factor within MNs, with a blockade of apoptosis possibly mediated by Aven up-regulation. MN swelling is associated with compromised Na,K-ATPase activity and aggregation. mSOD1 mouse MNs accumulate mitochondria from the axon terminals and generate higher levels of superoxide, nitric oxide, and peroxynitrite than MNs in control mice. Nitrated and aggregated cytochrome c oxidase subunit-I and alpha-synuclein as well as nitrated SOD2 accumulate in mSOD1 mouse spinal cord. Mitochondria in mSOD1 mouse MNs accumulate NADPH diaphorase and inducible nitric oxide synthase (iNOS)-like immunoreactivity, and iNOS gene deletion extends significantly the life span of G93A-mSOD1 mice. Prior to MN loss, spinal interneurons degenerate. These results identify novel mechanisms for mitochondriopathy and MN degeneration in amyotrophic lateral sclerosis (ALS) mice involving blockade of apoptosis, accumulation of MN mitochondria with enhanced toxic potential from distal terminals, NOS localization in MN mitochondria and peroxynitrite damage, and early degeneration of alpha-synuclein(+) interneurons. The data support roles for oxidative stress, protein nitration and aggregation, and excitotoxicity as participants in the process of MN degeneration caused by mSOD1.

DNA methylation is an epigenetic mechanism for gene silencing engaged by DNA methyltransferase (Dnmt)-catalyzed methyl group transfer to cytosine residues in gene regulatory regions. It is unknown if aberrant DNA methylation can cause neurodegeneration. We tested the hypothesis that Dnmts can mediate neuronal cell death. Enforced expression of Dnmt3a induced degeneration of cultured NSC34 cells. During apoptosis of NSC34 cells induced by camptothecin, levels of Dnmt1 and Dnmt3a increased five-fold and two-fold, respectively, and 5-methylcytosine accumulated in nuclei. Truncation mutation of the Dnmt3a catalytic domain and Dnmt3a RNAi blocked apoptosis of cultured neurons. Inhibition of Dnmt catalytic activity with RG108 and procainamide protected cultured neurons from excessive DNA methylation and apoptosis. In vivo, Dnmt1 and Dnmt3a are expressed differentially during mouse brain and spinal cord maturation and in adulthood when Dnmt3a is abundant in synapses and mitochondria. Dnmt1 and Dnmt3a are expressed in motor neurons of adult mouse spinal cord, and, during their apoptosis induced by sciatic nerve avulsion, nuclear and cytoplasmic 5-methylcytosine immunoreactivity, Dnmt3a protein levels, and Dnmt enzyme activity increased preapoptotically. Inhibition of Dnmts with RG108 blocked completely the increase in 5-methycytosine and the apoptosis of motor neurons in mice. In human amyotrophic lateral sclerosis (ALS), motor neurons showed changes in Dnmt1, Dnmt3a, and 5-methylcytosine similar to experimental models. Thus, motor neurons can engage epigenetic mechanisms to drive apoptosis, involving Dnmt upregulation and increased DNA methylation. These cellular mechanisms could be relevant to human ALS pathobiology and disease treatment.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of motor neurons (MNs) that causes paralysis. Some forms of ALS are inherited, caused by mutations in the superoxide dismutase-1 (SOD1) gene. The mechanisms of human mutant SOD1 (mSOD1) toxicity to MNs are unresolved. Mitochondria in MNs might be key sites for ALS pathogenesis, but cause-effect relationships between mSOD1 and mitochrondiopathy need further study. We used transgenic mSOD1 mice to test the hypothesis that the mitochondrial permeability transition pore (mPTP) is involved in the MN degeneration of ALS. Components of the multi-protein mPTP are expressed highly in mouse MNs, including the voltage-dependent anion channel, adenine nucleotide translocator (ANT), and cyclophilin D (CyPD), and are present in mitochondria marked by manganese SOD. MNs in pre-symptomatic mSOD1-G93A mice form swollen megamitochondria with CyPD immunoreactivity. Early disease is associated with mitochondrial cristae remodeling and matrix vesiculation in ventral horn neuron dendrites. MN cell bodies accumulate mitochondria derived from the distal axons projecting to skeletal muscle. Incipient disease in spinal cord is associated with increased oxidative and nitrative stress, indicated by protein carbonyls and nitration of CyPD and ANT. Reducing the levels of CyPD by genetic ablation significantly delays disease onset and extends the lifespan of G93A-mSOD1 mice expressing high and low levels of mutant protein in a gender-dependent pattern. These results demonstrate that mitochondria have causal roles in the disease mechanisms in MNs in ALS mice. This work defines a new mitochondrial mechanism for MN degeneration in ALS.

Background Direct-acting antiviral (DAA) therapy for hepatitis C virus (HCV) infection has resulted in high rates of disease cure; however, not enough specialists currently are available to provide care. Objective To determine the efficacy of HCV treatment independently provided by nurse practitioners (NPs), primary care physicians (PCPs), or specialist physicians using DAA therapy. Design Nonrandomized, open-label clinical trial initiated in 2015. (ClinicalTrials.gov: NCT02339038) Setting 13 urban, federally qualified health centers (FQHCs) in the District of Columbia. Patients A referred sample of 600 patients, of whom 96% were black, 69% were male, 82% were treatment naive, and 20% had cirrhosis. Seventy-two percent of the patients had HCV genotype 1a infection. The baseline characteristics of patients seen by each provider type were similar. Intervention Patients were assigned in a nonrandomized but specified manner to receive treatment from 1 of 5 NPs, 5 PCPs, or 6 specialists. All providers underwent an identical 3-hour training session based on guidelines. Patients received treatment with ledipasvir–sofosbuvir, which was provided on site, according to U.S. Food and Drug Administration labeling requirements. Measurements Sustained virologic response (SVR). Results 516 patients achieved SVR, a response rate of 86% (95% CI, 83.0% to 88.7%), with no major safety signals. Response rates were consistent across the 3 provider types: NPs, 89.3% (CI, 83.3% to 93.8%); PCPs, 86.9% (CI, 80.6% to 91.7%); and specialists, 83.8% (CI, 79.0% to 87.8%). Patient loss to follow-up was the major cause of non-SVR. Limitation Nonrandomized patient distribution; possible referral bias. Conclusion In a real-world cohort of patients at urban FQHCs, HCV treatment administered by nonspecialist providers was as safe and effective as that provided by specialists. Nurse practitioners and PCPs with compact didactic training could substantially expand the availability of community-based providers to escalate HCV therapy, bridging existing gaps in the continuum of care for patients with HCV infection. Primary Funding Source National Institutes of Health and Gilead Sciences.

clinicaltrials.gov Identifier:NCT01878799.

Successful treatment of chronic HCV with peginterferon (PEGIFN) and ribavirin (RVN) is often limited by anemia. We performed the present study to determine if utilizing epoetin alpha (EPO) with or without a higher dose of RVN could enhance sustained virologic response (SVR). We randomized 150 treatment-naive patients with chronic HCV genotype 1 into 3 treatment groups: (1) PEGIFN alpha-2b (1.5 g/kg/week) ؉ weight-based RVN (WBR) 13.3 mg/kg/day (800 to 1400 mg/day); (2) PEGIFN alpha-2b ؉ WBRVN ؉ EPO (40,000 U/week); or (3) PEGIFN alpha-2b ؉ higher dose WBR 15.2 mg/kg/day (1000 to 1600 mg/day) ؉ EPO. We initiated EPO at the onset of therapy to maintain the hemoglobin between 12 and 15 g/dL. When required, we reduced RVN by 200-mg steps. African Americans compose 36% of the population. A significantly smaller percentage of group 2 patients had a decline in hemoglobin to less than 10 g/dL (9% versus 34%; P < 0.05) and required that the RVN dose be reduced (10% versus 40%; P < 0.05) compared to group 1 patients. Despite this, SVR was similar in these groups (19% to 29%). SVR was significantly greater (P < 0.05) in group 3 patients (49%). This resulted from a significant decline (P < 0.05) in relapse rate; only 8% versus 38% for groups 1 and 2. Conclusion: We conclude that using EPO in all subjects at the initiation of PEGIFN and RVN treatment will not enhance SVR given the same starting dose of RVN. In contrast, a higher starting dose of RVN was associated with a lower relapse rate and higher rate of SVR. (HEPATOLOGY 2007;46:371-379.)

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