IP3 signalling regulates exogenous RNAi in Caenorhabditis elegans.

RNA interference (RNAi) is a widespread and widely exploited phenomenon. Here, we show that changing inositol 1,4,5-trisphosphate (IP3) signalling alters RNAi sensitivity in Caenorhabditis elegans. Reducing IP3 signalling enhances sensitivity to RNAi in a broad range of genes and tissues. Conversely up-regulating IP3 signalling decreases sensitivity. Tissue-specific rescue experiments suggest IP3 functions in the intestine. We also exploit IP3 signalling mutants to further enhance the sensitivity of RNAi hypersensitive strains. These results demonstrate that conserved cell signalling pathways can modify RNAi responses, implying that RNAi responses may be influenced by an animal's physiology or environment.We thank A. Fire, K. Ford, S. Mitani and H. Peterkin for the provision of plasmids and strains. Some strains were provided by the CGC, which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440). Other strains were provided by the Mitani Lab through the National Bio‐Resource Project of the MEXT, Japan. We are grateful to J. Ahringer, B. Olofsson and members of the Baylis group for helpful discussions. AIN was funded by Trinity Hall College, Cambridge and the Cambridge European Trust. The work of MDS and RPV‐M was partially funded by a Miguel Servet Grant (CP11/00090) from the Health Research Institute Carlos III, which is partially supported by the European Regional Development Fund. RPV‐M is a Marie Curie fellow (CIG322034). RG was funded by the MRC (G0601106).This is the accepted manuscript. The final version is available from Embo Press at http://embor.embopress.org/content/early/2015/01/21/embr.201439585

Phosphodiesterase inhibition induces retinal degeneration, oxidative stress and inflammation in cone-enriched cultures of porcine retina.

nherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes 74 of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the 75 phototransduction and, mutations in genes related to its metabolism are responsible for different retinal 76 dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4e5% of the retinitis 77 pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether phar- 78 macological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina 79 similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants 80 from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, 81 as determined by TUNEL assay. Western blot analysis and immunostaining indicated that degeneration 82 was accompanied by caspase-3, calpain-2 activation and poly (ADP-ribose) accumulation. Oxidative stress 83 markers, total antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and nitric oxide 84 measurements revealed the presence of oxidative damage. Elevated TNF-alpha and IL-6, as determined by enzyme immunoassay, were also found in cone-enriched retinal explants treated with Zaprinast. Our 85 study suggests that this ex vivo model of retinal degeneration in porcine retina could be an alternative 86 model for therapeutic research into the mechanisms of photoreceptor death in cone-related diseases, 87 thus replacing or reducing animal experiments

Loss of glutathione redox homeostasis impairs proteostasis by inhibiting autophagy-dependent protein degradation

In the presence of aggregation-prone proteins, the cytosol and endoplasmic reticulum (ER) undergo a dramatic shift in their respective redox status, with the cytosol becoming more oxidized and the ER more reducing. However, whether and how changes in the cellular redox status may affect protein aggregation is unknown. Here, we show that C. elegans loss-of-function mutants for the glutathione reductase gsr-1 gene enhance the deleterious phenotypes of heterologous human, as well as endogenous worm aggregation-prone proteins. These effects are phenocopied by the GSH-depleting agent diethyl maleate. Additionally, gsr-1 mutants abolish the nuclear translocation of HLH-30/TFEB transcription factor, a key inducer of autophagy, and strongly impair the degradation of the autophagy substrate p62/SQST-1::GFP, revealing glutathione reductase may have a role in the clearance of protein aggregates by autophagy. Blocking autophagy in gsr-1 worms expressing aggregation-prone proteins results in strong synthetic developmental phenotypes and lethality, supporting the physiological importance of glutathione reductase in the regulation of misfolded protein clearance. Furthermore, impairing redox homeostasis in both yeast and mammalian cells induces toxicity phenotypes associated with protein aggregation. Together, our data reveal that glutathione redox homeostasis may be central to proteostasis maintenance through autophagy regulation.. The Spanish Ministry of Economy and Competitiveness supported EF-S and VG (BFU2016–78265-P), PA (BFU2016– 79313-P and MDM-2016–0687), and AM-V (BFU2015–64408-P). AM-V was also supported by the Instituto de Salud Carlos III (PI11/ 00072) and RPV-M (CPII16/00004, PI14/00949 and PI17/00011). All projects were cofinanced by the Fondo Social Europeo (FEDER). AM-V is a member of the GENIE and EU-ROS Cost Actions of the European Union and RPV-M is a Marie Curie Fellow (CIG322034, EU)

Study of USH1 Splicing Variants through Minigenes and Transcript Analysis from Nasal Epithelial Cells

Usher syndrome type I (USH1) is an autosomal recessive disorder characterized by congenital profound deafness, vestibular areflexia and prepubertal retinitis pigmentosa. The first purpose of this study was to determine the pathologic nature of eighteen USH1 putative splicing variants found in our series and their effect in the splicing process by minigene assays. These variants were selected according to bioinformatic analysis. The second aim was to analyze the USH1 transcripts, obtained from nasal epithelial cells samples of our patients, in order to corroborate the observed effect of mutations by minigenes in patient’s tissues. The last objective was to evaluate the nasal ciliary beat frequency in patients with USH1 and compare it with control subjects. In silico analysis were performed using four bioinformatic programs: NNSplice, Human Splicing Finder, NetGene2 and Spliceview. Afterward, minigenes based on the pSPL3 vector were used to investigate the implication of selected changes in the mRNA processing. To observe the effect of mutations in the patient’s tissues, RNA was extracted from nasal epithelial cells and RT-PCR analyses were performed. Four MYO7A (c.470G>A, c.1342_1343delAG, c.5856G>A and c.3652G>A), three CDH23 (c.2289+1G>A, c.6049G>A and c.8722+1delG) and one PCDH15 (c.3717+2dupTT) variants were observed to affect the splicing process by minigene assays and/or transcripts analysis obtained from nasal cells. Based on our results, minigenes are a good approach to determine the implication of identified variants in the mRNA processing, and the analysis of RNA obtained from nasal epithelial cells is an alternative method to discriminate neutral Usher variants from those with a pathogenic effect on the splicing process. In addition, we could observe that the nasal ciliated epithelium of USH1 patients shows a lower ciliary beat frequency than control subjects

Loss of glutathione redox homeostasis impairs proteostasis by inhibiting autophagy-dependent protein degradation

Trabajo presentado en el VII Spanish Worm Meeting (SWN), celebrado en Castelldefels (Barcelona) el 28 y 29 de marzo de 2019.Peer reviewe

Altered Antioxidant-Oxidant Status in the Aqueous Humor and Peripheral Blood of Patients with Retinitis Pigmentosa

Retinitis Pigmentosa is a common form of hereditary retinal degeneration constituting the largest Mendelian genetic cause of blindness in the developed world. It has been widely suggested that oxidative stress possibly contributes to its pathogenesis. We measured the levels of total antioxidant capacity, free nitrotyrosine, thiobarbituric acid reactive substances (TBARS) formation, extracellular superoxide dismutase (SOD3) activity, protein, metabolites of the nitric oxide/cyclic GMP pathway, heme oxygenase-I and inducible nitric oxide synthase expression in aqueous humor or/and peripheral blood from fifty-six patients with retinitis pigmentosa and sixty subjects without systemic or ocular oxidative stress-related disease. Multivariate analysis of covariance revealed that retinitis pigmentosa alters ocular antioxidant defence machinery and the redox status in blood. Patients with retinitis pigmentosa present low total antioxidant capacity including reduced SOD3 activity and protein concentration in aqueous humor. Patients also show reduced SOD3 activity, increased TBARS formation and upregulation of the nitric oxide/cyclic GMP pathway in peripheral blood. Together these findings confirmed the hypothesis that patients with retinitis pigmentosa present reduced ocular antioxidant status. Moreover, these patients show changes in some oxidative-nitrosative markers in the peripheral blood. Further studies are needed to clarify the relationship between these peripheral markers and retinitis pigmentosa

Metformin treatment reduces motor and neuropsychiatric phenotypes in the zQ175 mouse model of Huntington disease

16 páginas, 8 figuras, 1 tablaHuntington disease is a neurodegenerative condition for which there is no cure to date. Activation of AMP-activated protein kinase has previously been shown to be beneficial in in vitro and in vivo models of Huntington's disease. Moreover, a recent cross-sectional study demonstrated that treatment with metformin, a well-known activator of this enzyme, is associated with better cognitive scores in patients with this disease. We performed a preclinical study using metformin to treat phenotypes of the zQ175 mouse model of Huntington disease. We evaluated behavior (motor and neuropsychiatric function) and molecular phenotypes (aggregation of mutant huntingtin, levels of brain-derived neurotrophic factor, neuronal inflammation, etc.). We also used two models of polyglutamine toxicity in Caenorhabditis elegans to further explore potential mechanisms of metformin action. Our results provide strong evidence that metformin alleviates motor and neuropsychiatric phenotypes in zQ175 mice. Moreover, metformin intake reduces the number of nuclear aggregates of mutant huntingtin in the striatum. The expression of brain-derived neurotrophic factor, which is reduced in mutant animals, is partially restored in metformin-treated mice, and glial activation in mutant mice is reduced in metformin-treated animals. In addition, using worm models of polyglutamine toxicity, we demonstrate that metformin reduces polyglutamine aggregates and restores neuronal function through mechanisms involving AMP-activated protein kinase and lysosomal function. Our data indicate that metformin alleviates the progression of the disease and further supports AMP-activated protein kinase as a druggable target against Huntington's disease.We thank the CGC (funded by NIH Office of Research Infrastructure Programs; ref: P40 OD010440) for worm strains, the CHDI Foundation for the gift of the zQ175 mice, and the Microscopy Unit of IIS-La Fe for their kind help. We also thank David Hervás and Victoria Fornés for their critical comments on the statistical analysis of the paper. R.P.V.-M. holds a “Miguel Servet” fellowship (Ref: CPII16/00004) funded by the Instituto de Salud Carlos III (ISCIII, Madrid, Spain) and by Social European Funds and grants from the ISCIII (PI14/00949 and PI17/00011) and Fundació Telemarató de la TV3 (ref: 559), which covered the work of A.S. and M.D.S. The funds from the ISCIII are partially supported by the European Regional Development Fund. RPVM is also a Marie Curie fellow (CIG322034, EU). This work has been partially funded by a grant from the CIBERER (ACCI2016) to R.P.V.-M., J.M.M., and P.S., which covered the work of M. A.G.-G. P.S. holds a grant from Generalitat Valenciana (PrometeoII/2014/029).Peer reviewe

Metformin intake associates with better cognitive function in patients with Huntington's disease.

Huntington's disease (HD) is an inherited, dominant neurodegenerative disorder caused by an abnormal expansion of CAG triplets in the huntingtin gene (htt). Despite extensive efforts to modify the progression of HD thus far only symptomatic treatment is available. Recent work suggests that treating invertebrate and mice HD models with metformin, a well-known AMPK activator which is used worldwide to treat type 2-diabetes, reduces mutant huntingtin from cells and alleviates many of the phenotypes associated to HD. Herein we report statistical analyses of a sample population of participants in the Enroll-HD database, a world-wide observational study on HD, to assess the effect of metformin intake in HD patients respect to cognitive status using linear models. This cross-sectional study shows for the first time that the use of metformin associates with better cognitive function in HD patients

Partial dependence plots showing the interaction between metformin intake and HD status regarding cognitive scores.

<p>(A-F) Result of the analysis of the different cognitive tests. G Graph showing the result of the analysis of all cognitive tests (Cognitive Score). These plots are produced using the estimates from the fitted linear regression models, so cognitive values are adjusted for age, gender, BMI and ISCED. The p-values included are assessing the effect of the interactions, that is, the differential effect of metformin intake in HD-patients compared to controls.</p

Cognitive results among the HD patients and controls ^a.

<p>Cognitive results among the HD patients and controls <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179283#t002fn001" target="_blank">^a</a>.</p