Mechanical force of uterine occupation enables large vesicle extrusion from proteostressed maternal neurons.

Large vesicle extrusion from neurons may contribute to spreading pathogenic protein aggregates and promoting inflammatory responses, two mechanisms leading to neurodegenerative disease. Factors that regulate extrusion of large vesicles, such as exophers produced by proteostressed C. elegans touch neurons, are poorly understood. Here we document that mechanical force can significantly potentiate exopher extrusion from proteostressed neurons. Exopher production from the C. elegans ALMR neuron peaks at adult day 2 or 3, coinciding with the C. elegans reproductive peak. Genetic disruption of C. elegans germline, sperm, oocytes, or egg/early embryo production can strongly suppress exopher extrusion from the ALMR neurons during the peak period. Conversely, restoring egg production at the late reproductive phase through mating with males or inducing egg retention via genetic interventions that block egg-laying can strongly increase ALMR exopher production. Overall, genetic interventions that promote ALMR exopher production are associated with expanded uterus lengths and genetic interventions that suppress ALMR exopher production are associated with shorter uterus lengths. In addition to the impact of fertilized eggs, ALMR exopher production can be enhanced by filling the uterus with oocytes, dead eggs, or even fluid, supporting that distention consequences, rather than the presence of fertilized eggs, constitute the exopher-inducing stimulus. We conclude that the mechanical force of uterine occupation potentiates exopher extrusion from proximal proteostressed maternal neurons. Our observations draw attention to the potential importance of mechanical signaling in extracellular vesicle production and in aggregate spreading mechanisms, making a case for enhanced attention to mechanobiology in neurodegenerative disease.

Large vesicle extrusions from C. elegans neurons are consumed and stimulated by glial-like phagocytosis activity of the neighboring cell.

Caenorhabditis elegans neurons under stress can produce giant vesicles, several microns in diameter, called exophers. Current models suggest that exophers are neuroprotective, providing a mechanism for stressed neurons to eject toxic protein aggregates and organelles. However, little is known of the fate of the exopher once it leaves the neuron. We found that exophers produced by mechanosensory neurons in C. elegans are engulfed by surrounding hypodermal skin cells and are then broken up into numerous smaller vesicles that acquire hypodermal phagosome maturation markers, with vesicular contents gradually degraded by hypodermal lysosomes. Consistent with the hypodermis acting as an exopher phagocyte, we found that exopher removal requires hypodermal actin and Arp2/3, and the hypodermal plasma membrane adjacent to newly formed exophers accumulates dynamic F-actin during budding. Efficient fission of engulfed exopher-phagosomes to produce smaller vesicles and degrade their contents requires phagosome maturation factors SAND-1/Mon1, GTPase RAB-35, the CNT-1 ARF-GAP, and microtubule motor-associated GTPase ARL-8, suggesting a close coupling of phagosome fission and phagosome maturation. Lysosome activity was required to degrade exopher contents in the hypodermis but not for exopher-phagosome resolution into smaller vesicles. Importantly, we found that GTPase ARF-6 and effector SEC-10/exocyst activity in the hypodermis, along with the CED-1 phagocytic receptor, is required for efficient production of exophers by the neuron. Our results indicate that the neuron requires specific interaction with the phagocyte for an efficient exopher response, a mechanistic feature potentially conserved with mammalian exophergenesis, and similar to neuronal pruning by phagocytic glia that influences neurodegenerative disease.

Traumatic injury compromises nucleocytoplasmic transport and leads to TDP-43 pathology.

Traumatic brain injury (TBI) is a predisposing factor for many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), and chronic traumatic encephalopathy (CTE). Although defects in nucleocytoplasmic transport (NCT) is reported ALS and other neurodegenerative diseases, whether defects in NCT occur in TBI remains unknown. We performed proteomic analysis on Drosophila exposed to repeated TBI and identified resultant alterations in several novel molecular pathways. TBI upregulated nuclear pore complex (NPC) and nucleocytoplasmic transport (NCT) proteins as well as alter nucleoporin stability. Traumatic injury disrupted RanGAP1 and NPC protein distribution in flies and a rat model and led to coaggregation of NPC components and TDP-43. In addition, trauma-mediated NCT defects and lethality are rescued by nuclear export inhibitors. Importantly, genetic upregulation of nucleoporins in vivo and in vitro triggered TDP-43 cytoplasmic mislocalization, aggregation, and altered solubility and reduced motor function and lifespan of animals. We also found NUP62 pathology and elevated NUP62 concentrations in postmortem brain tissues of patients with mild or severe CTE as well as co-localization of NUP62 and TDP-43 in CTE. These findings indicate that TBI leads to NCT defects, which potentially mediate the TDP-43 pathology in CTE.

Changes to the TDP-43 and FUS Interactomes Induced by DNA Damage.

The RNA-binding proteins TDP-43 and FUS are tied as the third leading known genetic cause for amyotrophic lateral sclerosis (ALS), and TDP-43 proteopathies are found in nearly all ALS patients. Both the natural function and contribution to pathology for TDP-43 remain unclear. The intersection of functions between TDP-43 and FUS can focus attention for those natural functions mostly likely to be relevant to disease. Here, we compare the role played by TDP-43 and FUS, maintaining chromatin stability for dividing HEK293T cells. We also determine and compare the interactomes of TDP-43 and FUS, quantitating changes in those before and after DNA damage. Finally, selected interactions with known importance to DNA damage repair were validated by co-immunoprecipitation assays. This study uncovered TDP-43 and FUS binding to several factors important to DNA repair mechanisms that can be replication-dependent, -independent, or both. These results provide further evidence that TDP-43 has an important role in DNA stability and provide new ways that TDP-43 can bind to the machinery that guards DNA integrity in cells.

TDP-43 regulates transcription at protein-coding genes and Alu retrotransposons.

The 43-kDa transactive response DNA-binding protein (TDP-43) is an example of an RNA-binding protein that regulates RNA metabolism at multiple levels from transcription and splicing to translation. Its role in post-transcriptional RNA processing has been a primary focus of recent research, but its role in regulating transcription has been studied for only a few human genes. We characterized the effects of TDP-43 on transcription genome-wide and found that TDP-43 broadly affects transcription of protein-coding and noncoding RNA genes. Among protein-coding genes, the effects of TDP-43 were greatest for genes <30 thousand base pairs in length. Surprisingly, we found that the loss of TDP-43 resulted in increased evidence for transcription activity near repetitive Alu elements found within expressed genes. The highest densities of affected Alu elements were found in the shorter genes, whose transcription was most affected by TDP-43. Thus, in addition to its role in post-transcriptional RNA processing, TDP-43 plays a critical role in maintaining the transcriptional stability of protein-coding genes and transposable DNA elements.

Transcription-Dependent Formation of Nuclear Granules Containing FUS and RNA Pol II.

Purified recombinant FUsed in Sarcoma (FUS) assembles into an oligomeric state in an RNA-dependent manner to form large condensates. FUS condensates bind and concentrate the C-terminal domain of RNA polymerase II (RNA Pol II). We asked whether a granule in cells contained FUS and RNA Pol II as suggested by the binding of FUS condensates to the polymerase. We developed cross-linking protocols to recover protein particles containing FUS from cells and separated them by size exclusion chromatography. We found a significant fraction of RNA Pol II in large granules containing FUS with diameters of >50 nm or twice that of the RNA Pol II holoenzyme. Inhibition of transcription prevented the polymerase from associating with the granules. Altogether, we found physical evidence of granules containing FUS and RNA Pol II in cells that possess properties comparable to those of in vitro FUS condensates.

Implementación del análisis de riesgo en la industria alimentaria mediante la metodología AMEF: enfoque práctico y conceptual / Implementing Risk Analysis in Food Industry through Modal Analysis of Effects and Failures (MAEF): Practical and Conceptual Approach / Implementação da análise de risco na indústria alimentícia mediante a Análise Modal de Efeitos e Falhas (AMEF): enfoque prático e conceitual

El análisis de riesgo mediante el Análisis Modal de Efectos y Fallas (AMEF) se aplicó y se incorporó en conjunto con el Análisis de Peligros y Puntos Críticos de Control (HACCP) para establecer la evaluación de riesgos en una maquiladora de pavo deshuesado. En este trabajo se calculó y se predijo, por medio de la significancia del riesgo, la importancia de establecer medidas preventivas en las etapas de proceso más vulnerables. El cálculo de la significancia se realizó obteniendo el Índice de Criticidad (IC). Los puntos críticos de control se establecieron con la metodología del árbol de decisiones, que se enfocó en aquellas etapas que mostraron tener los valores más altos relativos al IC. Las principales causas posibles que generan una desviación de los puntos críticos de control fueron enlistadas y analizadas a través de un análisis causa-raíz, con el uso del diagrama de Ishikawa. La integración del análisis de riesgo dentro de un plan HACCP demostró proveer amplias ventajas que facilitan el control de los procesos de manufactura y el aseguramiento de la salud pública a los consumidores finales, al generar alimentos inocuos y de alta calidad, al tiempo que mejora el desempeño operacional del ciclo productivo. Se identificaron las etapas de almacenamiento y descongelación como los principales segmentos con tendencia a mostrar altos valores de IC. Las acciones correctivas sugeridas bajaron notablemente los valores del IC por debajo del límite aceptable. Los resultados del presente estudio muestran claramente la importancia de la incorporación de un buen sistema de control sistemático para la gestión de riesgos en la industria avícola.

Risk Analysis through the Modal Analysis of Effects and Failures (MAEF) was applied and incorporated together with the Hazard and Critical Control Points Analysis (HCCPA) in order to establish the assessment of risk in a maquiladora of boneless turkey. Through risk significance, the importance of establishing preventive measures during the most vulnerable stages of the process was calculated and predicted in this paper. Significance was calculated by obtaining the Criticality Index (CI). The critical control points were established using the decision tree methodology, which was focused on those stages showing the highest values related to the CI. The main possible causes that generate a deviation from the critical control points were listed and analyzed through a root-cause analysis, using Ishikawa's diagram. The integration of risk analysis in a HCCPA plan proved to offer advantages that facilitate the control of manufacturing processes and the assurance of public health to final consumers, by generating innocuous and high quality food products and at the same time improving the operational performance of the productive cycle. The storing and thawing stages were identified as the main segments tending to show high CI values. The suggested corrective actions significantly lowered the CI values below the acceptable limit. The results of this study clearly show the importance of incorporating a good system of systematic control for risk management in the poultry industry.

A análise de risco mediante a Análise Modal de Efeitos e Falhas (AMEF) se aplicou e se incorporou em conjunto com a Análise de Perigos e Pontos Críticos de Controle (HACCP) para estabelecer a avaliação de riscos em uma maquiladora de peru desossado. Neste trabalho se calculou e se previu, através da significância do risco, da importância de estabelecer medidas preventivas nas etapas de processo mais vulneráveis. O cálculo da significância se realizou obtendo o Índice de Criticidade (IC). Os pontos críticos de controle se estabeleceram com a metodologia árvore de decisões, que se focou naquelas etapas que mostraram ter os valores mais altos relativos ao IC. As principais causas possíveis que geram um desvio dos pontos críticos de controle foram elencadas e analisadas através de uma análise causa-raiz, com o uso do diagrama de Ishikawa. A integração da análise de risco dentro de um plano HACCP demonstrou prover amplas vantagens que facilitam o controle dos processos de manufatura e a garantia da saúde pública aos consumidores finais, ao gerar alimentos inócuos e de alta qualidade, ao mesmo tempo em que melhora o desempenho operacional do ciclo produtivo. Identificaram-se as etapas de armazenamento e descongelação como os principais segmentos com tendência a mostrar altos valores de IC. As ações corretivas sugeridas bajaram notavelmente os valores do IC por baixo do limite aceitável. Os resultados deste estudo mostram claramente a importância da incorporação de um bom sistema de controle sistemático para a gestão de riscos na indústria avícola.