Identification of genes in trinucleotide repeat RNA toxicity pathways in C. elegans

Myotonic dystrophy disorders are caused by expanded CUG repeats in non-coding regions. To reveal mechanisms of CUG repeat pathogenesis we used C. elegans expressing CUG repeats to identify gene inactivations that modulate CUG repeat toxicity. We identified 15 conserved genes that function as suppressors or enhancers of CUG repeat-induced toxicity and modulate formation of nuclear RNA foci by CUG repeats. These genes regulated CUG repeat-induced toxicity through distinct mechanisms including RNA export and RNA clearance, suggesting that CUG repeat toxicity is mediated by multiple pathways. A subset is shared with other degenerative disorders. The nonsense-mediated mRNA decay (NMD) pathway plays a conserved role regulating CUG repeat RNA transcript levels and toxicity, and NMD recognition of toxic RNAs depends on 3′UTR GC nucleotide content. Our studies suggest a broader surveillance role for NMD where variations in this pathway influence multiple degenerative diseases

Exploiting the Multifunctionality of M2+/Imidazole−Etidronates for Proton Conductivity (Zn2+) and Electrocatalysis (Co2+, Ni2+) toward the HER, OER, and ORR

This work deals with the synthesis and characterization of one-dimensional (1D) imidazole-containing etidronates, [M2(ETID)(Im)3]·nH2O (M = Co2+ and Ni2+; n = 0, 1, 3) and Zn2(ETID)2(H2O)2](Im)2, as well as the corresponding Co2+/Ni2+ solid solutions. Depending on the water content, metal ions in the isostructural Co2+ and Ni2+ derivatives are octahedrally coordinated (n = 3) or consist of octahedral together with dimeric trigonal bipyramidal (n = 1) or square pyramidal (n = 0) environments. The imidazole molecule acts as a ligand (Co2+, Ni2+ derivatives) or charge-compensating protonated species (Zn2+ derivative). For the latter, the proton conductivity is determined to be ∼6 × 10−4 S·cm−1 at 80 °C and 95% relative humidity (RH). By pyrolyzing in 5%H2−Ar at 700−850 °C, core−shell electrocatalysts consisting of Co2+-, Ni2+-phosphides or Co2+/Ni2+-phosphide solid solution particles embedded in a N-doped carbon graphitic matrix are obtained, which exhibit improved catalytic performances compared to the non-N-doped carbon materials. Co2+ phosphides consist of CoP and Co2P in variable proportions according to the used precursor and pyrolytic conditions. However, the Ni2+ phosphide is composed of Ni2P exclusively at high temperatures. Exploration of the electrochemical activity of these metal phosphides toward the OER, ORR, and HER reactions reveals that the anhydrous Co2(ETID)(Im)3 pyrolyzed at 800 °C (CoP/Co2P = 80/20 wt %) is the most active trifunctional electrocatalyst, with good integrated capabilities as an anode for overall water splitting (cell voltage of 1.61 V) and potential application in Zn−air batteries. This solid also displays a moderate activity for the HER with an overpotential of 156 mV and a Tafel slope of 79.7 mV·dec−1 in 0.5 M H2SO4. Ni2+- and Co2+/Ni2+-phosphide solid solutions show lower electrochemical performances, which are correlated with the formation of less active crystalline phases.The work at UMA was funded by PID2019-110249RB-I00 (MICIU/AEI, Spain) and PY20-00416 (Junta de Andalucia, Spain/FEDER) research projects. A.V.-C. thanks MICIU for PRE2020-094459 student grant; M.B.-G. thanks PAIDI2020-DOC_00272 research grant (Junta de Andalucia, Spain) and R.M.P.C. thanks University of Malaga under Plan Propio de Investigación for financial support. Funding for open access charge: Universidad de Málaga/CBUA (PMCID# PMC8915163

Inhibition of RNA lariat debranching enzyme suppresses TDP-43 toxicity in ALS disease models

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease that primarily affects upper and lower motor neurons and results in paralysis and death within 3-5 years of disease onset. Currently there is no cure. Although many factors contribute to disease pathogenesis, TDP-43 aggregation was found to play a major role in the pathogenesis of familial and sporadic cases of ALS and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). TDP-43 is primarily nuclear, but in the disease state it is found in cytoplasmic inclusions in affected brain regions of patients with ALS and FTD. Therefore strategies that will target cytoplasmic TDP-43 and not interfere with essential nuclear functions will be important for designing of therapeutics. To gain insight into disease pathogenesis we used a yeast proteinopathy model system that recapitulates two basic features of the disease: TDP-43 aggregation and toxicity. To define modifiers of TDP-43 mediated toxicity we previously performed a deletion screen in yeast. Here we report the results from this screen and we further focus our studies on a particular gene that has important implications for therapeutics, which is Dbr1. Dbr1 is a lariat debranching enzyme that debranches the intronic lariats that accumulate during splicing in yeast and mammals. Here we show that in the absence of Dbr1 activity intronic lariats accumulate at high levels in the cytoplasm and serve as decoys for TDP-43 aggregates. Since loss of RNA binding capacity of TDP-43 is important for toxicity we propose a model in which cytoplasmic TDP-43 becomes toxic by sequestering RNAs or other RNA binding proteins that are important for cell viability. Importantly, we show that this approach has an effect on TDP-43 mediated toxicity in mammalian cells and primary rat neurons

Inhibition of RNA lariat debranching enzyme suppresses TDP-43 toxicity in ALS disease models

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease that primarily affects upper and lower motor neurons and results in paralysis and death within 3-5 years of disease onset. Currently there is no cure. Although many factors contribute to disease pathogenesis, TDP-43 aggregation was found to play a major role in the pathogenesis of familial and sporadic cases of ALS and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). TDP-43 is primarily nuclear, but in the disease state it is found in cytoplasmic inclusions in affected brain regions of patients with ALS and FTD. Therefore strategies that will target cytoplasmic TDP-43 and not interfere with essential nuclear functions will be important for designing of therapeutics. To gain insight into disease pathogenesis we used a yeast proteinopathy model system that recapitulates two basic features of the disease: TDP-43 aggregation and toxicity. To define modifiers of TDP-43 mediated toxicity we previously performed a deletion screen in yeast. Here we report the results from this screen and we further focus our studies on a particular gene that has important implications for therapeutics, which is Dbr1. Dbr1 is a lariat debranching enzyme that debranches the intronic lariats that accumulate during splicing in yeast and mammals. Here we show that in the absence of Dbr1 activity intronic lariats accumulate at high levels in the cytoplasm and serve as decoys for TDP-43 aggregates. Since loss of RNA binding capacity of TDP-43 is important for toxicity we propose a model in which cytoplasmic TDP-43 becomes toxic by sequestering RNAs or other RNA binding proteins that are important for cell viability. Importantly, we show that this approach has an effect on TDP-43 mediated toxicity in mammalian cells and primary rat neurons

Inhibition of RNA lariat debranching enzyme suppresses TDP-43 toxicity in ALS disease models

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease that primarily affects upper and lower motor neurons and results in paralysis and death within 3-5 years of disease onset. Currently there is no cure. Although many factors contribute to disease pathogenesis, TDP-43 aggregation was found to play a major role in the pathogenesis of familial and sporadic cases of ALS and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). TDP-43 is primarily nuclear, but in the disease state it is found in cytoplasmic inclusions in affected brain regions of patients with ALS and FTD. Therefore strategies that will target cytoplasmic TDP-43 and not interfere with essential nuclear functions will be important for designing of therapeutics. To gain insight into disease pathogenesis we used a yeast proteinopathy model system that recapitulates two basic features of the disease: TDP-43 aggregation and toxicity. To define modifiers of TDP-43 mediated toxicity we previously performed a deletion screen in yeast. Here we report the results from this screen and we further focus our studies on a particular gene that has important implications for therapeutics, which is Dbr1. Dbr1 is a lariat debranching enzyme that debranches the intronic lariats that accumulate during splicing in yeast and mammals. Here we show that in the absence of Dbr1 activity intronic lariats accumulate at high levels in the cytoplasm and serve as decoys for TDP-43 aggregates. Since loss of RNA binding capacity of TDP-43 is important for toxicity we propose a model in which cytoplasmic TDP-43 becomes toxic by sequestering RNAs or other RNA binding proteins that are important for cell viability. Importantly, we show that this approach has an effect on TDP-43 mediated toxicity in mammalian cells and primary rat neurons

Inhibition of RNA lariat debranching enzyme suppresses TDP-43 toxicity in ALS disease models

ALS is a devastating neurodegenerative disease primarily affecting motor neurons. Mutations in TDP-43 cause some forms of the disease, and cytoplasmic TDP-43 aggregates accumulate in degenerating neurons of most ALS patients. Thus, strategies aimed at targeting the toxicity of cytoplasmic TDP-43 aggregates may be effective. Here we report results from two genome-wide loss-of-function TDP-43 toxicity suppressor screens in yeast. The strongest suppressor of TDP-43 toxicity was deletion of Dbr1, which encodes RNA lariat debranching enzyme. We show that in the absence of Dbr1 enzymatic activity intronic lariats accumulate in the cytoplasm and likely act as decoys to sequester TDP-43 away from interfering with essential cellular RNAs and RNA-binding proteins. Knockdown of Dbr1 in a human neuronal cell line or in primary rodent neurons is also sufficient to rescue TDP-43 toxicity. Our findings provide insight into TDP-43 cytotoxicity and suggest decreasing Dbr1 activity could be a potential therapeutic approach for ALS