195 research outputs found
Polyglutamine Atrophin provokes neurodegeneration in Drosophila by repressing fat
No full textLarge alterations in transcription accompany neurode- generation in polyglutamine (polyQ) diseases. These patho- logies manifest both general polyQ toxicity and mutant protein-specific effects. In this study, we report that the fat tumour suppressor gene mediates neurodegeneration in- duced by the polyQ protein Atrophin. We have monitored early transcriptional alterations in a Drosophila model of Dentatorubral-pallidoluysian Atrophy and found that polyQ Atrophins downregulate fat. Fat protects from neu- rodegeneration and Atrophin toxicity through the Hippo kinase cascade. Fat/Hippo signalling does not provoke neurodegeneration by stimulating overgrowth; rather, it alters the autophagic flux in photoreceptor neurons, there- by affecting cell homeostasis. Our data thus provide a crucial insight into the specific mechanism of a polyQ disease and reveal an unexpected neuroprotective role of the Fat/Hippo pathway
Autophagie (De la caractérisation moléculaire et cellulaire aux applications en santé) / Autophagy (Moving from Molecular and Cellular characterization towards Applications in Health and Diseases)
No full textSéminaire organisé Frank Lafont (Institut Pasteur, Lille, France) et Patrice Codogno (INEM, Paris, France) par du 18 au 23 mai 2015 Participants Christian Behrends, Martine, Biard-Piechaczyk, Patricia Boya, Patrice Codogno, Ivan Dikic, Zvulun Elazar, Manolis Fanto, Mathias Faure, Gian Maria Fimia, Malene Hansen, Nicholas Ktistakis, Frank Lafont, Serge Mostowy, Christian Münz, Tassula Proikas-Cezanne, Emmanuelle Passegué, Fulvio Reggiori, Anne Simonsen, Sharon Toose, Isabelle Vergne -- Résumé ..
SLCO5A1 and synaptic assembly genes contribute to impulsivity in juvenile myoclonic epilepsy
No full textElevated impulsivity is a key component of attention-deficit hyperactivity disorder (ADHD), bipolar disorder and juvenile myoclonic epilepsy (JME). We performed a genome-wide association, colocalization, polygenic risk score, and pathway analysis of impulsivity in JME (n = 381). Results were followed up with functional characterisation using a drosophila model. We identified genome-wide associated SNPs at 8q13.3 (P = 7.5 × 10−9) and 10p11.21 (P = 3.6 × 10−8). The 8q13.3 locus colocalizes with SLCO5A1 expression quantitative trait loci in cerebral cortex (P = 9.5 × 10−3). SLCO5A1 codes for an organic anion transporter and upregulates synapse assembly/organisation genes. Pathway analysis demonstrates 12.7-fold enrichment for presynaptic membrane assembly genes (P = 0.0005) and 14.3-fold enrichment for presynaptic organisation genes (P = 0.0005) including NLGN1 and PTPRD. RNAi knockdown of Oatp30B, the Drosophila polypeptide with the highest homology to SLCO5A1, causes over-reactive startling behaviour (P = 8.7 × 10−3) and increased seizure-like events (P = 6.8 × 10−7). Polygenic risk score for ADHD genetically correlates with impulsivity scores in JME (P = 1.60 × 10−3). SLCO5A1 loss-of-function represents an impulsivity and seizure mechanism. Synaptic assembly genes may inform the aetiology of impulsivity in health and disease.</p
Dysregulated CREB3 cleavage at the nuclear membrane induces karyoptosis-mediated cell death
No full textCancer cells often exhibit resistance to apoptotic cell death, but they may be vulnerable to other types of cell death. Elucidating additional mechanisms that govern cancer cell death is crucial for developing new therapies. Our research identified cyclic AMP-responsive element-binding protein 3 (CREB3) as a crucial regulator and initiator of a unique cell death mechanism known as karyoptosis. This process is characterized by nuclear shrinkage, deformation, and the loss of nuclear components following nuclear membrane rupture. We found that the N-terminal domain (aa 1-230) of full-length CREB3 (CREB3-FL), which is anchored to the nuclear inner membrane (INM), interacts with lamins and chromatin DNA. This interaction maintains a balance between the outward force exerted by tightly packed DNA and the inward constraining force, thereby preserving INM integrity. Under endoplasmic reticulum (ER) stress, aberrant cleavage of CREB3-FL at the INM leads to abnormal accumulation of the cleaved form of CREB3 (CREB3-CF). This accumulation disrupts the attachment of CREB3-FL to the INM, resulting in sudden rupture of the nuclear membrane and the onset of karyoptosis. Proteomic studies revealed that CREB3-CF overexpression induces a DNA damage response akin to that caused by UVB irradiation, which is associated with cellular senescence in cancer cells. These findings demonstrated that the dysregulation of CREB3-FL cleavage is a key factor in karyoptotic cell death. Consequently, these findings suggest new therapeutic strategies in cancer treatment that exploit the process of karyoptosis.</p
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