Highlights d C9-HRE alters subcellular localization of proteins involved in RNA and protein metabolism d eRF1 accumulates in complex nuclear invaginations in C9-ALS neurons d C9-ALS neurons display hyperactive NMD and reduced translation d eRF1 and UPF1 are modulators of C9-HRE toxicity in vivo

Ischemic stroke is a devastating disease with limited therapeutic options. It is very urgent to find a new target for drug development. Here we found that the blood level of MIF in ischemic stroke patients is upregulated. To figure out the pathological role of MIF in ischemic stroke, both in vitro and in vivo studies were conducted. For in vitro studies, primary cortical neuron cultures and adult rat brain endothelial cells (ARBECs) were subjected to oxygen-glucose deprivation (OGD)/reoxygenation. Middle cerebral artery occlusion (MCAo) rodent models were used for in vivo studies. The results show that MIF exerts no direct neuronal toxicity in primary culture but disrupts tight junction in ARBECs. Furthermore, administration of MIF following MCAo shows the deleterious influence on strokeinduced injury by destroying the tight junction of blood-brain barrier and increasing the infarct size. In contrast, administration of MIF antagonist ISO-1 has the profound neuroprotective effect. Our results demonstrate that MIF might be a good drug target for the therapy of stroke.

The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a hexanucleotide repeat expansion in C9orf72 (C9-HRE). While RNA and dipeptide repeats produced by the C9-HRE disrupt nucleocytoplasmic transport, the proteins that become redistributed remain unknown. Here, we utilized subcellular fractionation coupled with tandem mass spectrometry and identified 126 proteins, enriched for protein translation and RNA metabolism pathways, which collectively drive a shift towards a more cytosolic proteome in C9-HRE cells. Amongst these was ETF1, which regulates translation termination and nonsense-mediated decay (NMD). ETF1 accumulates within elaborate nuclear envelope invaginations in patient iPSC-neurons and postmortem tissue and mediates a protective shift from protein translation to NMD-dependent mRNA degradation. Overexpression of ETF1 and the NMD-driver UPF1 ameliorate C9-HRE toxicity in vivo. Our findings provide a resource for proteome-wide nucleocytoplasmic alterations across neurodegenerationassociated repeat expansion mutations and highlight ETF1 and NMD as therapeutic targets in C9orf72-associated ALS/FTD. KEYWORDSAmyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), C9orf72, ETF1, nonsense mediated decay (NMD), UPF1, nucleocytoplasmic proteome, iPSCs, motor neurons. through three non-exclusive mechanisms 5-8 . Several reports have shown that C9orf72 expression is decreased in patients suggesting that haploinsufficiency contributes to pathogenesis 9, 10 . Gain-of-function neurotoxic effects occur through the production of aberrant C9-HRE RNA molecules 11 , as well as through dipeptide repeat proteins (DPRs) translated by a non-ATG dependent mechanism from the HRE 12, 13 . The repeat is bi-directionally transcribed and corresponding RNA sense and antisense molecules are detected by fluorescence in situ hybridization (FISH) as predominantly nuclear RNA foci in patient cells and tissue 11,13,14 . Moreover, five C9-HRE DPRs (GA, GP, GR, PR, PA) have been detected with antigen-specific antibodies in patient samples where they accumulate in cytoplasmic and nuclear aggregates in the frontal and motor cortex as well as the spinal cord 15,16 .While the relative contribution of loss-of-function effects, as well as the dominant source of toxic gain-of-function effects (RNA or DPRs) is still an open-ended question, substantial and converging evidence suggests that the C9-HRE disrupts the balance of proteins that are transported between the nucleus and the cytoplasm. The long C9-RNA that is transcribed from the repeat expansion binds and sequesters RNA-binding proteins in the nucleus 11 . The argininerich GR and PR C9-DPRs bind and sequester a number of proteins with low complexity domains that assemble into membrane-less organelles through liquid-liquid phase separation 17, 18 . These include RNA granules, nucleoli and various components of the nuclear pore complex (NPC). Consequently, a series of groundbreaking genetic studies in C9-HRE Drosophila and yeast mod...

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WW domain-containing transcription regulator 1 (TAZ) and Yes-associated protein (YAP) are transcriptional co-activators traditionally studied together as a part of the Hippo pathway and best known for their roles in stem cell proliferation and differentiation. Despite their similarities, TAZ and YAP can exert divergent cellular effects by differentially interacting with other signaling pathways that regulate stem cell maintenance or differentiation. In the developing central nervous system, In this study, we show that TAZ regulates astrocytic differentiation and maturation of postnatal neural stem and progenitor cells (NPCs), and that TAZ mediates some but not all of the effects of bone morphogenetic protein (BMP) signaling on astrocytic development. By contrast, TAZ and YAP both mediate effects on NPC fate of β1-integrin and integrin-linked kinase (ILK) signaling, and these effects are dependent on extracellular matrix (ECM) cues. These findings demonstrate that TAZ and YAP perform divergent functions in the regulation of astrocyte differentiation, where YAP regulates cell cycle states of astrocytic progenitors and TAZ regulates differentiation and maturation from astrocytic progenitors into astrocytes.