Biology subjects

Arellano, M.

Publications and source records attributed to Arellano, M..

6 recordsLinked to original sources

bioRxiv2025

Mitophagy-related prohibitin 2 is an orthoflavivirus restriction factor targeted for degradation during infection

1.Orthoflaviviruses (OFVs) are the primary cause of arboviral disease worldwide, leading to large numbers of hospitalisations, sequelae and deaths associated. Viral genome replication is catalysed by non-structural protein 5 (NS5), the largest and most conserved protein in these viruses. Here, we used quantitative proteomics to identify host cell interactors of Zika virus (ZIKV), Usutu virus (USUV), and West Nile virus (WNV) NS5 proteins. A total of 141 proteins were detected in the analysis, being 26 of them associated with all three NS5s. Downregulation of myoferlin and LGALS3BP led to decreases in the virus yields, indicating that their presence is needed for efficient virus replication. Conversely, silencing of mitophagy-related prohibitin 2 (PHB2) resulted in significant increases in ZIKV and USUV titres and genomic RNA. Supporting a connection between this antiviral behaviour and mitophagy, an inhibitor of this pathway also led to larger virus titres and viral RNA copies. During infection, PHB2 protein levels gradually decreased, becoming transiently undetectable, and suggesting that it is specifically targeted by the virus for degradation. Ectopic expression of NS5 alone did not affect PHB2 intracellular abundance, however a significant decrease was observed in cells expressing the viral protease NS2B/NS3. Its elimination, was more pronounced in cells where both viral enzymes were co-expressed, supporting that NS5 could be assisting PHB2 recognition by NS2B/NS3. Overall, our results support that PHB2 is an orthoflaviviral restriction factor which is targeted for degradation to favour viral replication. 2. IMPORTANCEOrthoflaviviruses (OFVs) are one of the main causes of disease transmitted by mosquitoes, with millions of infections occurring annually, and large numbers of deaths associated. Some important members include viruses causing dengue, yellow fever, and Zika-associated disease (e.g. microcephaly). OFVs contain a genome which is copied by a highly conserved viral protein termed NS5. Prohibitin 2 (PHB2) is a host cellular protein involved in different cellular processes including mitophagy, a mechanism to remove damaged mitochondria. Here, we show that human PHB2 interacts with orthoflaviviral NS5. Depletion of PHB2 results in increased viral yields, suggesting that this protein restricts orthoflaviviral infection. We found that PHB2 is targeted for degradation by the orthoflaviviral protease in a process aided by NS5, supporting that several viral proteins act concertedly to eliminate PHB2, counteracting its antiviral activity, and thus favouring infection.

microbiology↗

bioRxiv2025

Identification of Pesticides Associated with an Increased Risk of Parkinson's Disease using a Multi-Screen Approach

Parkinsons Disease (PD) is a progressive neurodegenerative disease characterized by aggregation and transmission of alpha-synuclein (-syn) protein and loss of dopaminergic neurons. The etiology of PD is multifactorial involving both genetic and environmental factors. Pesticide exposure has been associated with PD, but it is still unclear which of the hundreds of chemically and structurally diverse pesticides confer this association. While there are numerous pesticides currently registered for use in the United States, in this study, we focused on 62 pesticides used in the California Central Valley. We used 2 cell-based screens and a recently developed pesticide-wide association study (PWAS) analysis to identify candidates that increase the risk of PD. One cell-based screen tested for pesticides that alter autophagy and the other tested for their effect on -syn transmission. To establish biological plausibility, pesticides that were positive in all 3 screens were tested for dopaminergic neurotoxicity in an in vivo zebrafish (ZF) model. The autophagy screen resulted in a total of 22 hits for alterations to either autophagosomes (16 hits) and lysosomes (14 hits) out of the 62 pesticides tested. The -syn transmission screen resulted in 29 hits, and the PWAS resulted in 34 hits. Six pesticides were positive in all 3 screens and four of these pesticides induced aminergic neuron loss in ZF larvae. The majority of the pesticides identified in our screens have not previously been implicated as risk factors for PD but should be considered in future studies.

pharmacology and toxicology↗

bioRxiv2025

The Pesticide Chlorpyrifos Increases the Risk of Parkinson's Disease

Background and PurposePesticides have been associated with an increased risk of Parkinsons disease (PD), but it is unclear which specific pesticides contribute to this association and whether it is causal. Since chlorpyrifos (CPF) exposure has been implicated as a risk factor for PD, we investigated its association to incident PD and if this association is biologically plausible using human, rodent, and zebrafish (ZF) studies. MethodsThe association of CPF with PD was assessed using the UCLA PEG study (829 PD and 824 control subjects), and proximity-based exposure estimates from living or working near agricultural CPF use. For the mammalian studies, 6 months old male C57BL/6 mice were divided into two groups, CPF and controls, for open field, rotarod, and wire hang behavioral testing. Mice were then exposed to CPF in an inhalation chamber (0.65-2.9 mg/m3/day) for 6 hrs./day 5 days/wk., whereas control mice were exposed to vehicle alone. Behavioral tests were performed before and 2.5 months after CPF exposure following a 3-day washout. Mice were then perfused for immunohistochemical analysis. For the mechanistic studies, ZF embryos were treated with CPF (250 nM) 24 hours post fertilization for 5-7 days. Behavioral testing was performed using the Viewpoint Imaging System. Neuronal loss and microglial activation were determined using immunohistochemistry. Neuronal autophagic flux was determined using autophagy modulators in GFP-LC3 transgenic ZF and Western blots. ResultsLong-term residential CPF exposure was linked to an increased risk of developing PD with an odds ratio of 2.68 (CI 1.58-4.55). Mice exposed to aerosolized CPF developed motor impairment and a significant loss of dopaminergic neurons in the substantia nigra and activation of microglia. TH positive neurons in the substantia nigra (SN) had significantly higher levels of phosphoserine 129 (pS129) -synuclein (-syn), a marker for pathological phosphorylated -syn, and ubiquitin. In contrast, neither pS129 -syn or ubiquitin accumulated in TH neurons in the VTA after CPF exposure. Consistent with the mice data, CPF exposure resulted in impairment of locomotor activity and selective loss of aminergic neurons in ZF. We also found an increase in neuronal apoptosis and microglial activation. Importantly, dopamine neuron loss was found to be at least partially dependent on {gamma}1-synuclein (closest functional homologue to human -syn) as neuronal loss did not occur in {gamma}1-synuclein knockout ZF. Using an in vivo ZF assay, we found impaired autophagic flux and an increase in lysosomal labelling within the zebrafish brain. CPF exposure also led to elevated {gamma}1-synuclein and p62 (autophagic cargo protein) levels consistent with impaired degradation. Furthermore, induction of autophagy was protective, supporting the hypothesis that impaired autophagic flux is at least partially responsible for neuron loss following CPF exposure. ConclusionsCPF exposure is associated with an increased risk of developing PD and this association is likely causal since PD-like pathology was recapitulated in animal models. Furthermore, impaired autophagic flux appears to underly this toxicity, a pathway implicated in the pathogenesis of PD.

neuroscience↗

bioRxiv2025

An In Vivo Model of Alpha-Synuclein Spread from Gut to Brain

BackgroundParkinsons disease is a progressive neurodegenerative disorder characterized by the presence of pathological aggregation of the protein alpha-synuclein and the loss of dopaminergic neurons in the substantia nigra. There is evidence that misfolding and propagation of alpha-synuclein aggregates through networks of interconnected neurons is responsible for the pathological spread and progressive neuron loss. However, in vivo models demonstrating such pathological progression remain elusive. ResultsThis study utilizes a zebrafish model in order to interrogate the mechanisms of alpha-synuclein toxicity and spread. We describe the development of a zebrafish model of endogenous neuronal human alpha-synuclein expression that causes, in young fish, behavioral and neuronal changes as well as microglia activation. In aged fish, alpha-synuclein expression induces a slow but progressive pathological phenotype manifesting in neuron loss within the gut and the CNS. This model is further utilized to seed gut pathology by incorporating a novel method of feeding human alpha-synuclein preformed fibrils in order to initiate protein misfolding at an early age. The combination of endogenous neuronal expression of alpha-synuclein and the exogenous addition of misfolded protein facilitates the development of brain pathology and subsequent neuron loss in the CNS. In addition to the pathological alterations induced with the fibril feeding model, genetic changes were identified by single cell RNA sequencing. These gene changes resulted in pathway alteration that implicate neurodegenerative disease processes. ConclusionThis model of alpha-synuclein pathology is useful for understanding mechanisms underlying disease initiation and can replicate the progressive development of pathological synuclein accumulation. It has the potential to induce neuron to neuron spread and also offers a way to explore what interventions may prevent such pathological progression.

neuroscience↗

bioRxiv2022

Transcriptomic and DNA methylation modifications during fruit ripening and in response to ABA treatment in sweet cherry

Abscisic acid (ABA) plays a key role in the ripening process of non-climacteric fruits, triggering pigment production, fruit softening, and sugar accumulation. Transcriptomic studies show that ABA modifies the expression of several ripening-related genes, but to date, the epigenetic approach has not been utilized to characterize the role of ABA during this process. Therefore, this work aimed to perform transcriptomic and DNA methylation analyses of fruit samples treated with ABA during the fruit ripening process in the non-climacteric sweet cherry model. RNA-seq analyses revealed an overrepresentation of transcripts annotated in functional categories related to ABA response, secondary metabolism, and sugar synthesis. In contrast, Whole Genome Bisulfite Sequencing (WGBS) revealed DNA hypomethylation in the 5UTR region of genes related to carotene catabolism. Genes encoding xyloglucan enzymes were regulated transcriptionally and epigenetically during ripening. ABA treatment enhanced color development and ripening. GO analysis of DEGs in the RNA-seq of the ABA treatment revealed expression variations in genes encoding members of the Aux/IAA and ARF families. In the WGBS, genes encoding enzymes of the cytokinin biosynthesis had differential DNA methylation after the ABA treatment. Our work shows the genetic factors modulated by ABA at the genetic and epigenetic levels during non-climacteric ripening.

plant biology↗

bioRxiv2020

TP53 abnormalities correlate with immune infiltration and are associated with response to flotetuzumab, an investigational immunotherapy, in acute myeloid leukemia

PurposeSomatic TP53 mutations and 17p deletions with genomic loss of TP53 occur in 37-46% of acute myeloid leukemia (AML) cases with adverse risk cytogenetics and are associated with primary induction failure (PIF), high risk of relapse and dismal prognosis. Herein, we aimed to characterize the immune landscape of TP53 mutated AML and to determine whether TP53 abnormalities identify a patient subgroup that may benefit from T-cell targeting immunotherapy approaches. Experimental DesignThe NanoString Pan-Cancer IO 360 assay was used for the immune transcriptomic analysis of 64 diagnostic bone marrow (BM) samples from adults with TP53 mutated AML (n=42) or TP53 wild type AML (n=22), and 35 BM samples from heavily pretreated patients with relapsed/refractory (R/R) AML (11 cases with TP53 mutations and/or 17p deletion with genomic loss of TP53) who received immunotherapy with flotetuzumab, an investigational CD123xCD3 bispecific DART(R) molecule (NCT02152956). In silico data series included The Cancer Genome Atlas (TCGA) cohort and a Dutch-Belgian Cooperative Trial Group for Hematology-Oncology (HOVON) cohort. ResultsAll TCGA cases with TP53 mutations (n=13) expressed higher levels of negative immune checkpoints, inflammatory chemokines, interferon (IFN)-{gamma}-inducible molecules, and had a higher tumor inflammation signature (TIS) score, compared with TCGA cases with other risk-defining molecular lesions. The comparison between TP53 mutated and TP53 wild type primary BM samples showed higher expression of IFNG, FoxP3, immune checkpoints and markers of exhaustion and senescence in the former cohort and allowed the computation of a 34-gene immune classifier prognostic for overall survival. In vitro modeling experiments with AML cell lines showed heightened expression of IFN-{gamma} and inflammation pathway genes in KG-1 cells (loss-of-function mutation of TP53) compared with Kasumi-1 cells (gain-of-function mutation of TP53). Finally, 5 out of 11 (45.5%) patients with R/R AML and TP53 abnormalities showed evidence of anti-leukemic activity of flotetuzumab immunotherapy and had higher TIS, FoxP3, CD8 T-cell abundance, inflammatory chemokine and PD1 gene expression scores at baseline compared with non-responders. ConclusionsThis study provides evidence for a correlation between IFN-{gamma}-dominant immune subtypes and TP53 abnormalities. The anti-leukemic activity with flotetuzumab encourages further study of this immunotherapeutic approach in this patient subgroup.

immunology↗