Enforced dimerization between XBP1s and ATF6f enhances the protective effects of the UPR in models of neurodegeneration.

Alteration to endoplasmic reticulum (ER) proteostasis is observed in a variety of neurodegenerative diseases associated with abnormal protein aggregation. Activation of the unfolded protein response (UPR) enables an adaptive reaction to recover ER proteostasis and cell function. The UPR is initiated by specialized stress sensors that engage gene expression programs through the concerted action of the transcription factors ATF4, ATF6f, and XBP1s. Although UPR signaling is generally studied as unique linear signaling branches, correlative evidence suggests that ATF6f and XBP1s may physically interact to regulate a subset of UPR target genes. In this study, we designed an ATF6f/XBP1s fusion protein termed UPRplus that behaves as a heterodimer in terms of its selective transcriptional activity. Cell-based studies demonstrated that UPRplus has a stronger effect in reducing the abnormal aggregation of mutant huntingtin and α-synuclein when compared to XBP1s or ATF6 alone. We developed a gene transfer approach to deliver UPRplus into the brain using adeno-associated viruses (AAVs) and demonstrated potent neuroprotection in vivo in preclinical models of Parkinson's disease and Huntington's disease. These results support the concept in which directing UPR-mediated gene expression toward specific adaptive programs may serve as a possible strategy to optimize the beneficial effects of the pathway in different disease conditions.

Whole-Genome sequencing and comparative genomics of Mycobacterium spp. from farmed Atlantic and coho salmon in Chile.

Several members of the Mycobacterium genus cause invasive infections in humans and animals. According to a recent phylogenetic analysis, some strains of Mycobacterium salmoniphilum (Msal), which are the main culprit in bacterial outbreaks in freshwater fish aquaculture, have been assigned to a separate branch containing Mycobacterium franklinii (Mfra), another species that causes infections in humans. However, this genus is little studied in an aquaculture context. Here, we isolated four Mycobacterium spp. strains from freshwater cultures of Atlantic and coho salmon in Chile and performed whole-genome sequencing for deep genomic characterization. In addition, we described the gross pathology and histopathology of the outbreaks. Several bioinformatic analyses were performed using the genomes of these four Mycobacterium isolates in conjunction with those of Msal strains, four Msal-like strains, and one Mfra strains, plus 17 other publicly available Mycobacterium genomes. We found that three isolates are clustered into the Msal branch, whereas one isolate clustered with the Mfra/Msal-like strains. We further evaluated the presence of virulence and antimicrobial resistance genes and observed that the four isolates were closely related to the Msal and Msal-like taxa and carried several antimicrobial resistance and virulence genes that are similar to those of other pathogenic members of the Mycobacterium clade. Altogether, our characterization Msal and Msal-like presented here shed new light on the basis of mycobacteriosis provides quantitative evidence that Mycobacterium strains are a potential risk for aquaculture asetiological agents of emerging diseases, and highlight their biological scopes in the aquaculture industry.

Targeting of the unfolded protein response (UPR) as therapy for Parkinson's disease.

Parkinson's disease is the second most common neurodegenerative disorder, leading to the progressive decline of motor control due to the loss of dopaminergic neurons in the substantia nigra pars compacta. At the molecular level, Parkinson's disease share common molecular signatures with most neurodegenerative diseases including the accumulation of misfolded proteins in the brain. Alteration in the buffering capacity of the proteostasis network during aging is proposed as one of the triggering steps leading to abnormal protein aggregation in this disease, highlighting disturbances in the function of the endoplasmic reticulum (ER). The ER is the main subcellular compartment involved in protein folding and quality control. ER stress triggers a signalling reaction known as the unfolded protein response (UPR), which aims restoring proteostasis through the induction of adaptive programs or the activation of cell death pathways when damage is chronic and cannot be repaired. Here, we overview most evidence linking ER stress to Parkinson's disease. Strategies to alleviate ER stress by targeting specific components of the UPR using small molecules and gene therapy are highlighted.

Multilocus sequence typing detects new Piscirickettsia salmonis hybrid genogroup in Chilean fish farms: Evidence for genetic diversity and population structure.

Piscirickettsia salmonisis the causative bacterial pathogen of piscirickettsiosis, a salmonid disease that causes notable mortalities in the worldwide aquaculture industry. Published research describes the phenotypic traits, virulence factors, pathogenicity and antibiotic-resistance potential for various P. salmonisstrains. However, evolutionary and genetic information is scarce for P. salmonis. The present study used multilocus sequence typing (MLST) to gain insight into the population structure and evolution of P. salmonis. Forty-two Chilean P. salmonisisolates, as well as the type strain LF-89T , were recovered from diseased Salmo salar, Oncorhynchus kisutchand Oncorhynchus mykissfrom two Chilean Regions. MLST assessed the loci sequences of dnaK, efp, fumC, glyA, murG, rpoD and trpB. Bioinformatics analyses established the genetic diversity among P. salmonis isolates (H = 0.5810). A total of 23 sequence types (ST) were identified, 53.48% of which were represented by ST1, ST5 and ST2. Population structure analysis through polymorphism patterns showed few polymorphic sites (218 nucleotides from 4,010 bp), while dN/dS ratio analysis indicated purifying selection for dnaK, epf, fumC, murG, and rpoD but neutral selection for the trpB loci. The standardized index of association indicated strong linkage disequilibrium, suggesting clonal population structure. However, recombination events were detected in a group of seven isolates. Findings included genogroups homologous to the LF-89T and EM-90 strains, as well as a seven-isolate hybrid genogroup recovered from both assessed regions (three O. mykiss and four S. salar isolates). The presented MLST scheme has comparative potential, with promising applications in studying distinct P. salmonis isolates (e.g., from different hosts, farms, geographical areas) and in understanding the epidemiology of this pathogen.

A new model to study cell-to-cell transfer of αSynuclein in vivo.

Parkinson's disease (PD) compromises motor control due to the loss of dopaminergic neurons in the substantia nigra pars compacta. At the histopathological level, PD is characterized by the accumulation of Lewy bodies, large protein inclusions containing aggregated αSynuclein (αSyn). The progression of PD involves the spreading of αSyn misfolding through the brain mediated by a prion-like mechanism, where the protein is transferred between cells. Here we report that αSyn internalization is a dynamic process, where the protein transits through different sub-cellular compartments. Importantly, cells incorporating αSyn develop larger protein-like inclusions when compared to αSyn producing cells. We developed a new tool to monitor cell-to-cell transfer of αSyn in vivo using an adeno-associated viral (AAV) vector expressing αSyn fused to a red fluorescent protein in addition to soluble EGFP to label donor cells. Intra-nigral delivery of this reporter AAV construct allowed the visualization of αSyn incorporation into surrounding neurons. This work provides a new tool to study αSyn cell-to-cell transfer in vivo and may open new opportunities to study PD pathogenesis.

Control of dopaminergic neuron survival by the unfolded protein response transcription factor XBP1.

Parkinson disease (PD) is characterized by the selective loss of dopaminergic neurons of the substantia nigra pars compacta (SNpc). Although growing evidence indicates that endoplasmic reticulum (ER) stress is a hallmark of PD, its exact contribution to the disease process is not well understood. Here we report that developmental ablation of X-Box binding protein 1 (XBP1) in the nervous system, a key regulator of the unfolded protein response (UPR), protects dopaminergic neurons against a PD-inducing neurotoxin. This survival effect was associated with a preconditioning condition that resulted from induction of an adaptive ER stress response in dopaminergic neurons of the SNpc, but not in other brain regions. In contrast, silencing XBP1 in adult animals triggered chronic ER stress and dopaminergic neuron degeneration. Supporting this finding, gene therapy to deliver an active form of XBP1 provided neuroprotection and reduced striatal denervation in animals injected with 6-hydroxydopamine. Our results reveal a physiological role of the UPR in the maintenance of protein homeostasis in dopaminergic neurons that may help explain the differential neuronal vulnerability observed in PD.

Relationship among the physiologic channel interactions, spectral-ripple discrimination, and vowel identification in cochlear implant users.

The hypothesis of this study was that broader patterns of physiological channel interactions in the local region of the cochlea are associated with poorer spectral resolution in the same region. Electrically evoked compound action potentials (ECAPs) were measured for three to six probe electrodes per subject to examine the channel interactions in different regions across the electrode array. To evaluate spectral resolution at a confined location within the cochlea, spectral-ripple discrimination (SRD) was measured using narrowband ripple stimuli with the bandwidth spanning five electrodes: Two electrodes apical and basal to the ECAP probe electrode. The relationship between the physiological channel interactions, spectral resolution in the local cochlear region, and vowel identification was evaluated. Results showed that (1) there was within- and across-subject variability in the widths of ECAP channel interaction functions and in narrowband SRD performance, (2) significant correlations were found between the widths of the ECAP functions and narrowband SRD thresholds, and between mean bandwidths of ECAP functions averaged across multiple probe electrodes and broadband SRD performance across subjects, and (3) the global spectral resolution reflecting the entire electrode array, not the local region, predicts vowel identification.

Genetic Mapping and Phenotypic Analysis of GstE14 E.4.1 on Eye and Antennae Development in Drosophila melanogaster.

Genetic screens are valuable for identifying novel genes involved in the regulation of developmental processes. To identify genes associated with cell growth regulation in Drosophila melanogaster , a mutagenesis screen was performed. Undergraduate students participating in Fly-CURE phenotypically characterized the E.4.1 mutant which is associated with rough eyes and antennae overgrowth. Following complementation analysis and subsequent genomic sequencing, E.4.1 was identified as a novel mutant allele of GstE14 , a gene involved in ecdysone biosynthesis important for the timing of developmental events. The abnormal eye and antenna phenotypes observed resulting from the loss of GstE14 suggest its role in tissue growth.

Effects of the energy balance transition on bone mass and strength.

Chronic positive energy balance has surged among societies worldwide due to increasing dietary energy intake and decreasing physical activity, a phenomenon called the energy balance transition. Here, we investigate the effects of this transition on bone mass and strength. We focus on the Indigenous peoples of New Mexico in the United States, a rare case of a group for which data can be compared between individuals living before and after the start of the transition. We show that since the transition began, bone strength in the leg has markedly decreased, even though bone mass has apparently increased. Decreased bone strength, coupled with a high prevalence of obesity, has resulted in many people today having weaker bones that must sustain excessively heavy loads, potentially heightening their risk of a bone fracture. These findings may provide insight into more widespread upward trends in bone fragility and fracture risk among societies undergoing the energy balance transition.

Genomics of Re-Emergent Aeromonas salmonicida in Atlantic Salmon Outbreaks.

Furunculosis, caused by Aeromonas salmonicida, poses a significant threat to both salmonid and non-salmonid fish in diverse aquatic environments. This study explores the genomic intricacies of re-emergent A. salmonicida outbreaks in Atlantic salmon (Salmo salar). Previous clinical cases have exhibited pathological characteristics, such as periorbital hemorrhages and gastrointestinal abnormalities. Genomic sequencing of three Chilean isolates (ASA04, ASA05, and CIBA_5017) and 25 previously described genomes determined the pan-genome, phylogenomics, insertion sequences, and restriction-modification systems. Unique gene families have contributed to an improved understanding of the psychrophilic and mesophilic clades, while phylogenomic analysis has been used to identify mesophilic and psychrophilic strains, thereby further differentiating between typical and atypical psychrophilic isolates. Diverse insertion sequences and restriction-modification patterns have highlighted genomic structural differences, and virulence factor predictions can emphasize exotoxin disparities, especially between psychrophilic and mesophilic strains. Thus, a novel plasmid was characterized which emphasized the role of plasmids in virulence and antibiotic resistance. The analysis of antibiotic resistance factors revealed resistance against various drug classes in Chilean strains. Overall, this study elucidates the genomic dynamics of re-emergent A. salmonicida and provides novel insights into their virulence, antibiotic resistance, and population structure.

c-Abl Phosphorylates MFN2 to Regulate Mitochondrial Morphology in Cells under Endoplasmic Reticulum and Oxidative Stress, Impacting Cell Survival and Neurodegeneration.

The endoplasmic reticulum is a subcellular organelle key in the control of synthesis, folding, and sorting of proteins. Under endoplasmic reticulum stress, an adaptative unfolded protein response is activated; however, if this activation is prolonged, cells can undergo cell death, in part due to oxidative stress and mitochondrial fragmentation. Here, we report that endoplasmic reticulum stress activates c-Abl tyrosine kinase, inducing its translocation to mitochondria. We found that endoplasmic reticulum stress-activated c-Abl interacts with and phosphorylates the mitochondrial fusion protein MFN2, resulting in mitochondrial fragmentation and apoptosis. Moreover, the pharmacological or genetic inhibition of c-Abl prevents MFN2 phosphorylation, mitochondrial fragmentation, and apoptosis in cells under endoplasmic reticulum stress. Finally, in the amyotrophic lateral sclerosis mouse model, where endoplasmic reticulum and oxidative stress has been linked to neuronal cell death, we demonstrated that the administration of c-Abl inhibitor neurotinib delays the onset of symptoms. Our results uncovered a function of c-Abl in the crosstalk between endoplasmic reticulum stress and mitochondrial dynamics via MFN2 phosphorylation.

Examining the Relationship between the Lethality Assessment/Domestic Violence High-risk Team Monitoring (LAP/DVHRT) Program and Prosecution Outcomes.

Lethality assessment (LAP) and team monitoring of high-risk offenders (DVHRT) are recent U.S. policy innovations designed to identify domestic violence offenders who are at high risk for perpetrating serious or lethal violence against their intimate partners. One goal of LAP/DVHRT is to increase offenders' accountability for domestic violence within the legal system. This study examines associations between LAP/DVHRT and prosecution and sentencing outcomes using data on domestic violence offenses (n = 88) involving 37 offenders monitored by a DVHRT and 51 nonmonitored comparison offenders who were identified as high risk on the LAP. We use logistic and OLS regression to estimate models of six prosecution and sentencing outcomes for the full sample and for a sample matched using the coarsened exact matching technique (n = 73). Multivariate results indicate that when the treatment and comparison samples are matched and control variables are included in regression models, the LAP/DVHRT program is not associated with prosecution or conviction rates, number of charges, or bail amount. DVHRT monitoring is positively associated with sentence length in multivariate analysis and in models using the matched sample. Findings suggest that the LAP/DVHRT program increases offender accountability in the form of incapacitation at the sentencing stages.

Syringe disposal among injection drug users in San Francisco.

To assess the prevalence of improperly discarded syringes and to examine syringe disposal practices of injection drug users (IDUs) in San Francisco, we visually inspected 1000 random city blocks and conducted a survey of 602 IDUs. We found 20 syringes on the streets we inspected. IDUs reported disposing of 13% of syringes improperly. In multivariate analysis, obtaining syringes from syringe exchange programs was found to be protective against improper disposal, and injecting in public places was predictive of improper disposal. Few syringes posed a public health threat.

HIV risks and seroprevalence among Mexican American injection drug users in California.

Latinos in the United States are an ethnically diverse group disproportionately affected by HIV/AIDS. We describe HIV seroprevalence, HIV risk behaviors and utilization of health services among Mexican American injection drug users (IDUs) in California (n = 286) and compare them to White (n = 830) and African American (n = 314) IDUs. Study participants were recruited from syringe exchange programs (n = 24) in California. HIV seroprevalence among Mexican Americans (0.5%) was dramatically lower than Whites (5%) and African Americans (8%). Mexican Americans reported fewer sex-related risks than Whites and African Americans though injection-related risks remained high. Compared to Whites, Mexican Americans were more likely to participate in drug treatment during a 6 month period (AOR 1.5, 95% CI 1.1, 2.0) but less likely to receive any health care (AOR 0.6, 95% CI 0.5, 0.8). Exploring cultural and structural factors among Mexican American IDUs may offer new insights into how to maintain low rates of HIV seroprevalence and reduce barriers to health care utilization.

HIV prevalence and risk among heterosexual methamphetamine injectors in California.

This study funded by Centers for Disease Control compares HIV prevalence and risk behavior among heterosexual methamphetamine (n = 428) and nonmethamphetamine (n = 878) injectors in California, USA, during 2001-2003. While HIV was not highly prevalent among methamphetamine injectors (3%), sexual and injection risk behaviors were highly prevalent (ranging from 21% to 72%). In multivariate analyses, methamphetamine injectors had higher odds than nonmethamphetamine injectors of unprotected vaginal intercourse and sex with five or more sexual partners in the past 6 months and of distributive and receptive syringe sharing in the past 30 days. There was no significant difference in HIV sero-status by methamphetamine use. Suggestions are made for designing HIV prevention programs. The study's limitations are noted.

Non-prescription syringe sales in California: a qualitative examination of practices among 12 local health jurisdictions.

Legislation permitting non-prescription syringe sales (NPSS) was passed in 2004 in California as a structural intervention designed to expand access to syringes for injection drug users. As of December 2009, 19 of California's 61 local health jurisdictions (LHJs) have approved policies to authorize pharmacies to sell non-prescription syringes. The legislation faces termination in 2010 if current evaluation efforts fail to demonstrate outcomes defined in the legislation. Using qualitative methods, we examined the systems and procedures associated with implementation; identified facilitators and barriers to implementation among 12 LHJs, and documented the role of public health in initiating and sustaining local programs. We identified consistent activities that led to policy implementation among LHJs and discovered several barriers that were associated with failure to implement local programs. Factors leading to NPSS were public health leadership; an inclusive planning process, marketing the program as a public health initiative; learning from others' efforts, successes, and failures; and identifying acceptable syringe disposal options in advance of program implementation. Health departments that were confronted with political and moral arguments lost momentum and ultimately assigned a lower priority to the initiative citing the loss of powerful public health advocates or a lack of human resources. Additional barriers were law enforcement, elected officials, and pharmacy opposition, and failure to resolve syringe disposal options to the satisfaction of important stakeholders. The lessons learned in this study should provide useful guidance for the remaining LHJs in California without NPSS programs.

Comparing respondent-driven sampling and targeted sampling methods of recruiting injection drug users in San Francisco.

The objective of this article is to compare demographic characteristics, risk behaviors, and service utilization among injection drug users (IDUs) recruited from two separate studies in San Francisco in 2005, one which used targeted sampling (TS) and the other which used respondent-driven sampling (RDS). IDUs were recruited using TS (n = 651) and RDS (n = 534) and participated in quantitative interviews that included demographic characteristics, risk behaviors, and service utilization. Prevalence estimates and 95% confidence intervals (CIs) were calculated to assess whether there were differences in these variables by sampling method. There was overlap in 95% CIs for all demographic variables except African American race (TS: 45%, 53%; RDS: 29%, 44%). Maps showed that the proportion of IDUs distributed across zip codes were similar for the TS and RDS sample, with the exception of a single zip code that was more represented in the TS sample. This zip code includes an isolated, predominantly African American neighborhood where only the TS study had a field site. Risk behavior estimates were similar for both TS and RDS samples, although self-reported hepatitis C infection was lower in the RDS sample. In terms of service utilization, more IDUs in the RDS sample reported no recent use of drug treatment and syringe exchange program services. Our study suggests that perhaps a hybrid sampling plan is best suited for recruiting IDUs in San Francisco, whereby the more intensive ethnographic and secondary analysis components of TS would aid in the planning of seed placement and field locations for RDS.

The necroptosis machinery mediates axonal degeneration in a model of Parkinson disease.

Parkinson's disease (PD) is the second most common neurodegenerative condition, characterized by motor impairment due to the progressive degeneration of dopaminergic neurons in the substantia nigra and depletion of dopamine release in the striatum. Accumulating evidence suggest that degeneration of axons is an early event in the disease, involving destruction programs that are independent of the survival of the cell soma. Necroptosis, a programmed cell death process, is emerging as a mediator of neuronal loss in models of neurodegenerative diseases. Here, we demonstrate activation of necroptosis in postmortem brain tissue from PD patients and in a toxin-based mouse model of the disease. Inhibition of key components of the necroptotic pathway resulted in a significant delay of 6-hydroxydopamine-dependent axonal degeneration of dopaminergic and cortical neurons in vitro. Genetic ablation of necroptosis mediators MLKL and RIPK3, as well as pharmacological inhibition of RIPK1 in preclinical models of PD, decreased dopaminergic neuron degeneration, improving motor performance. Together, these findings suggest that axonal degeneration in PD is mediated by the necroptosis machinery, a process here referred to as necroaxoptosis, a druggable pathway to target dopaminergic neuronal loss.

Correction: The necroptosis machinery mediates axonal degeneration in a model of Parkinson disease.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.