TDP-43-M323K causes abnormal brain development and progressive cognitive and motor deficits associated with mislocalised and increased levels of TDP-43.

TDP-43 pathology is found in several neurodegenerative disorders, collectively referred to as "TDP-43 proteinopathies". Aggregates of TDP-43 are present in the brains and spinal cords of >97% of amyotrophic lateral sclerosis (ALS), and in brains of ∼50% of frontotemporal dementia (FTD) patients. While mutations in the TDP-43 gene (TARDBP) are usually associated with ALS, many clinical reports have linked these mutations to cognitive impairments and/or FTD, but also to other neurodegenerative disorders including Parkinsonism (PD) or progressive supranuclear palsy (PSP). TDP-43 is a ubiquitously expressed, highly conserved RNA-binding protein that is involved in many cellular processes, mainly RNA metabolism. To investigate systemic pathological mechanisms in TDP-43 proteinopathies, aiming to capture the pleiotropic effects of TDP-43 mutations, we have further characterised a mouse model carrying a point mutation (M323K) within the endogenous Tardbp gene. Homozygous mutant mice developed cognitive and behavioural deficits as early as 3 months of age. This was coupled with significant brain structural abnormalities, mainly in the cortex, hippocampus, and white matter fibres, together with progressive cortical interneuron degeneration and neuroinflammation. At the motor level, progressive phenotypes appeared around 6 months of age. Thus, cognitive phenotypes appeared to be of a developmental origin with a mild associated progressive neurodegeneration, while the motor and neuromuscular phenotypes seemed neurodegenerative, underlined by a progressive loss of upper and lower motor neurons as well as distal denervation. This is accompanied by progressive elevated TDP-43 protein and mRNA levels in cortex and spinal cord of homozygous mutant mice from 3 months of age, together with increased cytoplasmic TDP-43 mislocalisation in cortex, hippocampus, hypothalamus, and spinal cord at 12 months of age. In conclusion, we find that Tardbp M323K homozygous mutant mice model many aspects of human TDP-43 proteinopathies, evidencing a dual role for TDP-43 in brain morphogenesis as well as in the maintenance of the motor system, making them an ideal in vivo model system to study the complex biology of TDP-43.

Erratum: Generation and analysis of innovative genomically humanized knockin SOD1, TARDBP (TDP-43), and FUS mouse models.

[This corrects the article DOI: 10.1016/j.isci.2021.103463.].

Generation and analysis of innovative genomically humanized knockin SOD1, TARDBP (TDP-43), and FUS mouse models.

Amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) is a fatal neurodegenerative disorder, and continued innovation is needed for improved understanding and for developing therapeutics. We have created next-generation genomically humanized knockin mouse models, by replacing the mouse genomic region of Sod1, Tardbp (TDP-43), and Fus, with their human orthologs, preserving human protein biochemistry and splicing with exons and introns intact. We establish a new standard of large knockin allele quality control, demonstrating the utility of indirect capture for enrichment of a genomic region of interest followed by Oxford Nanopore sequencing. Extensive analysis shows that homozygous humanized animals only express human protein at endogenous levels. Characterization of humanized FUS animals showed that they are phenotypically normal throughout their lifespan. These humanized strains are vital for preclinical assessment of interventions and serve as templates for the addition of coding or non-coding human ALS/FTD mutations to dissect disease pathomechanisms, in a physiological context.

Mice with endogenous TDP-43 mutations exhibit gain of splicing function and characteristics of amyotrophic lateral sclerosis.

TDP-43 (encoded by the gene TARDBP) is an RNA binding protein central to the pathogenesis of amyotrophic lateral sclerosis (ALS). However, how TARDBP mutations trigger pathogenesis remains unknown. Here, we use novel mouse mutants carrying point mutations in endogenous Tardbp to dissect TDP-43 function at physiological levels both in vitro and in vivo Interestingly, we find that mutations within the C-terminal domain of TDP-43 lead to a gain of splicing function. Using two different strains, we are able to separate TDP-43 loss- and gain-of-function effects. TDP-43 gain-of-function effects in these mice reveal a novel category of splicing events controlled by TDP-43, referred to as "skiptic" exons, in which skipping of constitutive exons causes changes in gene expression. In vivo, this gain-of-function mutation in endogenous Tardbp causes an adult-onset neuromuscular phenotype accompanied by motor neuron loss and neurodegenerative changes. Furthermore, we have validated the splicing gain-of-function and skiptic exons in ALS patient-derived cells. Our findings provide a novel pathogenic mechanism and highlight how TDP-43 gain of function and loss of function affect RNA processing differently, suggesting they may act at different disease stages.

Terapias antienvejecimiento aplicadas a la enfermedad de Alzheimer / Anti-ageing therapies in Alzheimer's disease

La enfermedad de Alzheimer es la causa más común de demencia en la población anciana. Actualmente no hay tratamientos efectivos para prevenir o retrasar el curso natural de dicha enfermedad. Numerosos estudios han proporcionado información de los procesos moleculares que subyacen en el envejecimiento biológico y, quizás más importante aún, de las posibles intervenciones para retrasar el envejecimiento y promover la longevidad saludable en sistemas modelo de laboratorio. La cuestión principal tratada en esta revisión es si una intervención que tiene propiedades antienvejecimiento puede alterar la aparición y/o progresión de la enfermedad de Alzheimer, una enfermedad en la que la edad es el mayor factor de riesgo. Diferentes intervenciones antienvejecimiento han demostrado prevenir (y posiblemente restaurar en algunos casos) varios parámetros reconocidos como síntomas centrales para el desarrollo de la enfermedad de Alzheimer. Además, se están dando los primeros pasos hacia la traslación de estos descubrimientos de laboratorio a aplicaciones clínicas (AU)

Alzheimer's disease is the most common cause of dementia in the elderly population. Currently, there are no effective treatments to prevent or delay the natural course of the disease. Numerous studies have provided information about the molecular processes underlying biological ageing and, perhaps more importantly, potential interventions to slow ageing and promote healthy longevity in laboratory model systems. The main issue addressed in this review is whether an intervention that has anti-ageing properties can alter the appearance and/or progression of Alzheimer's disease, a disease in which age is the biggest risk factor. Different anti-ageing interventions have been shown to prevent (and in some cases possibly restore) several parameters recognised as central symptoms to the development of Alzheimer's disease. In addition, they are taking the first steps towards translating these laboratory discoveries into clinical applications (AU)

[Anti-ageing therapies in Alzheimer's disease]. / Terapias antienvejecimiento aplicadas a la enfermedad de Alzheimer.

Alzheimer's disease is the most common cause of dementia in the elderly population. Currently, there are no effective treatments to prevent or delay the natural course of the disease. Numerous studies have provided information about the molecular processes underlying biological ageing and, perhaps more importantly, potential interventions to slow ageing and promote healthy longevity in laboratory model systems. The main issue addressed in this review is whether an intervention that has anti-ageing properties can alter the appearance and/or progression of Alzheimer's disease, a disease in which age is the biggest risk factor. Different anti-ageing interventions have been shown to prevent (and in some cases possibly restore) several parameters recognised as central symptoms to the development of Alzheimer's disease. In addition, they are taking the first steps towards translating these laboratory discoveries into clinical applications.

Terapia génica no invasiva en enfermedades neurológicas / Non invasive gene therapy in neurological diseases

Introduction. Brain gene therapy consists of introducing nucleic acids into nerve tissue whose expression may prove to betherapeutically useful. This genetic material is indirectly introduced by means of non invasive gene therapy into the bloodthereby avoiding its direct injection into the brain and the damage to the blood brain barrier.Aim. The different non invasive vectors and means of gene transfer to the central nervous system will be discussed.Development. There has been a remarkable breakthrough in recent years in non invasive gene transfer strategies into thecentral nervous system. The development of new serotypes of adenoassociated vectors, such as AAV9, and of functionalizednanoparticles, such as pegylated immunoliposomes, polymeric nanoparticles, pegylated nanoparticles, dendrimers, fullerens,as well as specific transporters specific to the low density lipoprotein receptor family, means that it is now possible tointroduce and express gene material in nerve tissue following peripherical administration of the above mentioned vectors.Conclusions. Non invasive gene therapy entails exciting new perspectives for the treatment of the numerous neurologicaldiseases for which there are no effective pharmacological treatments. Studies already performed on animals have provedto be highly promising and it is likely that, in the next few years, they will give rise to non invasive gene therapy procedureswhich will be useful and safe for treating patients (AU)

Introducción. La terapia génica cerebral consiste en la introducción de ácidos nucleicos en el tejido nervioso cuya expresiónpueda resultar de utilidad terapéutica. Mediante la terapia génica no invasiva, este material genético es introducido indirectamentepor vía sanguínea, evitando su inyección directa en el parénquima cerebral y el daño de la barrera hematoencefálica.Objetivo. Discutir los diferentes vectores y vías no invasivas de transferencia génica al sistema nervioso central.Desarrollo. En los últimos años se ha producido un giro espectacular en las estrategias para la transferencia génica no invasivadel sistema nervioso central. El desarrollo de nuevos serotipos de vectores adenoasociados, como AAV9, de una gama denanopartículas funcionalizadas, como inmunoliposomas pegilados, nanopartículas poliméricas, nanopartículas pegiladas,dendrímeros, fulerenos, así como de transportadores específicos de la familia de receptores de lipoproteína de baja densidad,permite introducir y expresar material génico en el tejido nervioso tras la administración periférica de dichos vectores.Conclusiones. La terapia génica no invasiva supone nuevas y excitantes perspectivas para el tratamiento de las numerosasenfermedades neurológicas para las cuales no existen tratamientos farmacológicos efectivos. Los estudios ya realizadosen animales resultan altamente prometedores y es probable que, en los próximos años, den lugar a procedimientos de terapia génica útiles y seguros para su uso en pacientes (AU)