Generation of induced pluripotent stem cells (CSSi017-A)(12862) from an ALS patient carrying a repeat expansion in the C9orf72 gene.

Genetic expansions of the hexanucleotide repeats (GGGGCC) in the C9orf72 gene appear in approximately 40% of patients with familial ALS and 7% of patients with sporadic ALS in the European population, making this mutation one of the most prevalent genetic mutations in ALS. Here, we generated a human induced pluripotent stem cell (hiPSC) line from the dermal fibroblasts of a patient carrying a 56-repeat expansion in an ALS disease-causing allele of C9orf72. These iPSCs showed stable amplification in vitro with normal karyotype and high expression of pluripotent markers and differentiated spontaneously in vivo into three germ layers.

271st ENMC international workshop: Towards a unifying effort to fight Kennedy's disease. 20-22 October 2023, Hoofddorp, Netherlands.

The workshop held in the Netherlands from October 20-22, 2023, united 27 scientists from academia, healthcare, and industry representing 11 countries, alongside four patient and charity representatives. Focused on Kennedy's Disease (KD), also known as spinal and bulbar muscular atrophy (SBMA), the workshop aimed to consolidate knowledge, align on clinical trial designs, and promote participative medicine for effective treatments. Discussions emphasized KD's molecular mechanisms, highlighting its status as a neuromuscular disorder with motor neuron degeneration. Strategies for therapeutic intervention, including AR activity modulation and targeting post-translational modifications, were proposed. The need for diagnostic, prognostic, and target engagement biomarkers was stressed. Challenges in patient stratification and clinical trial recruitment were acknowledged, with the International KD/SBMA Registry praised for its role. The workshop concluded with a patient-focused session, underscoring challenges in KD diagnosis and the vital support provided by patient associations.

Insights into the genetic epidemiology of spinal and bulbar muscular atrophy: prevalence estimation and multiple founder haplotypes in the Veneto Italian region.

BACKGROUND AND PURPOSE: Literature data on spinal and bulbar muscular atrophy (SBMA) epidemiology are limited and restricted to specific populations. The aim of our study was to accurately collect information about SBMA patients living in the Veneto region in Italy to compute reliable epidemiological data. Androgen receptor (AR) lineages were genotyped to evaluate the presence of a founder effect. METHODS: A prevalence survey considering all SBMA patients diagnosed in the Italian Veneto region on 31 January 2018 was carried out. The presence of different haplotypes obtained genotyping 15 polymorphic markers (single nucleotide polymorphisms and short tandem repeats) around the AR gene was evaluated. RESULTS: Based on 68 patients, the punctual prevalence of the disease on 31 January 2018 was 2.58/100 000 (95% confidence interval 1.65-3.35) in the male population. Five different haplotypes were identified, confirming the existence of multiple founder effects. It was also observed that, within the same haplotype, patients had a similar CAG repeat number (P-value < 0.001). CONCLUSIONS: A reliable estimation of SBMA prevalence in the Italian Veneto region was calculated which does not seem to be affected by a strong founder effect. Moreover, our data suggest that the length of the CAG expansion could be preserved in patients harbouring the same haplotype.

No effect of AR polyG polymorphism on spinal and bulbar muscular atrophy phenotype.

BACKGROUND AND PURPOSE: Disease severity varies considerably among patients with Spinal and Bulbar Muscular Atrophy (SBMA). Our aim was to investigate the role of androgen receptor (AR) polymorphic repeats in SBMA phenotype. METHODS: We analyzed the length of AR polyQ and polyG tracts in 159 SBMA patients. RESULTS: No relationship between polyG size or polyG/polyQ haplotypes and clinical phenotype was found. An independent negative correlation between polyQ-length and onset of weakness was confirmed (P < 0.001). CONCLUSIONS: The negative results of our study prompt to continue the search for potential disease modifiers in SBMA outside the AR gene.

Revisiting default mode network function in major depression: evidence for disrupted subsystem connectivity.

BACKGROUND: Major depressive disorder (MDD) is characterized by alterations in brain function that are identifiable also during the brain's 'resting state'. One functional network that is disrupted in this disorder is the default mode network (DMN), a set of large-scale connected brain regions that oscillate with low-frequency fluctuations and are more active during rest relative to a goal-directed task. Recent studies support the idea that the DMN is not a unitary system, but rather is composed of smaller and distinct functional subsystems that interact with each other. The functional relevance of these subsystems in depression, however, is unclear. METHOD: Here, we investigated the functional connectivity of distinct DMN subsystems and their interplay in depression using resting-state functional magnetic resonance imaging. RESULTS: We show that patients with MDD exhibit increased within-network connectivity in posterior, ventral and core DMN subsystems along with reduced interplay from the anterior to the ventral DMN subsystems. CONCLUSIONS: These data suggest that MDD is characterized by alterations of subsystems within the DMN as well as of their interactions. Our findings highlight a critical role of DMN circuitry in the pathophysiology of MDD, thus suggesting these subsystems as potential therapeutic targets.

CAG repeat length in androgen receptor gene is not associated with amyotrophic lateral sclerosis.

BACKGROUND: Epidemiological and clinical studies show higher prevalence of amyotrophic lateral sclerosis (ALS) in males than in females and more severe lesions in androgen receptor (AR)-expressing tissues. The AR gene contains a polymorphic CAG trinucleotide repeat, whose expansion over a certain threshold is toxic to motor neurons, causing spinal and bulbar muscular atrophy (SBMA). PURPOSE AND METHODS: We tested the hypothesis that the AR CAG repeat linked to SBMA is a risk factor for ALS. We analyzed AR CAG expansions in 336 patients with ALS and 100 controls. RESULTS: We found a negative association of AR CAG expansions with ALS susceptibility, clinical presentation, and survival. CONCLUSIONS: Our findings do not support a role of the AR CAG repeat length in ALS.

Calcium signalling-dependent mitochondrial dysfunction and bioenergetics regulation in respiratory chain Complex II deficiency.

Despite advanced knowledge on the genetic basis of oxidative phosphorylation-related diseases, the molecular and/or cellular determinants for tissue-specific dysfunction are not completely understood. Here, we report the cellular events associated with mitochondrial respiratory Complex II deficiency occurring before cell death. Mutation or chronic inhibition of Complex II determined a large increase of basal and agonist-evoked Ca(2+) signals in the cytosol and the mitochondria, in parallel with mitochondrial dysfunction characterized by membrane potential (Δψ(mit)) loss, [ATP] reduction and increased reactive oxygen species production. Cytosolic and mitochondrial Ca(2+) overload are linked to increased endoplasmic reticulum (ER) Ca(2+) leakage, and to SERCA2b and PMCA proteasome-dependent degradation. Increased [Ca(2+)](mit) is also contributed by decreased mitochondrial motility and increased ER-mitochondria contact sites. Interestingly, increased intracellular [Ca(2+)] activated on the one hand a compensatory Ca(2+)-dependent glycolytic ATP production and determined on the second hand mitochondrial pathology. These results revealed the primary function for Ca(2+) signalling in the control of mitochondrial dysfunction and cellular bioenergetics outcomes linked to respiratory chain Complex II deficiency.

Neurite extension occurs in the absence of regulated exocytosis in PC12 subclones.

We have investigated the process leading to differentiation of PC12 cells. This process is known to include extension of neurites and changes in the expression of subsets of proteins involved in cytoskeletal rearrangements or in neurosecretion. To this aim, we have studied a PC12 clone (trk-PC12) stably transfected with the nerve growth factor receptor TrkA. These cells are able to undergo both spontaneous and neurotrophin-induced morphological differentiation. However, both undifferentiated and nerve growth factor-differentiated trk-PC12 cells appear to be completely defective in the expression of proteins of the secretory apparatus, including proteins of synaptic vesicles and large dense-core granules, neurotransmitter transporters, and neurotransmitter-synthesizing enzymes. These results indicate that neurite extension can occur independently of the presence of the neurosecretory machinery, including the proteins that constitute the fusion machine, suggesting the existence of differential activation pathways for the two processes during neuronal differentiation. These findings have been confirmed in independent clones obtained from PC12-27, a previously characterized PC12 variant clone globally incompetent for regulated secretion. In contrast, the integrity of the Rab cycle appears to be necessary for neurite extension, because antisense oligonucleotides against the neurospecific isoform of Rab-guanosine diphosphate-dissociation inhibitor significantly interfere with process formation.

Interplay of the E box, the cyclic AMP response element, and HTF4/HEB in transcriptional regulation of the neurospecific, neurotrophin-inducible vgf gene.

vgf is a neurotrophin response-specific, developmentally regulated gene that codes for a neurosecretory polypeptide. Its transcription in neuronal cells is selectively activated by the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor, and neurotrophin 3, which induce survival and differentiation, and not by epidermal growth factor. We studied a short region of the rat vgf promoter which is essential for its regulated expression. A cyclic AMP response element (CRE) within this region is necessary for NGF induction of vgf transcription. Two sites upstream of CRE, an E box and a CCAAT sequence, bind nuclear protein complexes and are involved in transcriptional control. The E box has a dual role. It acts as an inhibitor in NIH 3T3 fibroblasts, together with a second E box located downstream, and as a stimulator in the NGF-responsive cell line PC12. By expression screening, we have isolated the cDNA for a basic helix-loop-helix transcription factor, a homolog of the HTF4/HEB E protein, that specifically binds the vgf promoter E box. The E protein was present in various cell lines, including PC12 cells, and was a component of a multiprotein nuclear complex that binds the promoter in vitro. The E box and CRE cooperate in binding to this complex, which may be an important determinant for neural cell-specific expression.