Neuroblastoma Cells Depend on CSB for Faithful Execution of Cytokinesis and Survival

Neuroblastoma, the most common extra-cranial solid tumor of early childhood, is one of the major therapeutic challenges in child oncology: it is highly heterogenic at a genetic, biological, and clinical level. The high-risk cases have one of the least favorable outcomes amongst pediatric tumors, and the mortality rate is still high, regardless of the use of intensive multimodality therapies. Here, we observed that neuroblastoma cells display an increased expression of Cockayne Syndrome group B (CSB), a pleiotropic protein involved in multiple functions such as DNA repair, transcription, mitochondrial homeostasis, and cell division, and were recently found to confer cell robustness when they are up-regulated. In this study, we demonstrated that RNAi-mediated suppression of CSB drastically impairs tumorigenicity of neuroblastoma cells by hampering their proliferative, clonogenic, and invasive capabilities. In particular, we observed that CSB ablation induces cytokinesis failure, leading to caspases 9 and 3 activation and, subsequently, to massive apoptotic cell death. Worthy of note, a new frontier in cancer treatment, already proved to be successful, is cytokinesis-failure-induced cell death. In this context, CSB ablation seems to be a new and promising anticancer strategy for neuroblastoma therapy.

Cockayne syndrome, MEN1, and genomic variants: Exome sequencing is changing our view of the genetic landscape

The availability of genomic sequencing for inherited diseases provides a more complete molecular basis for how an individual's genetic landscape influences clinical outcome. We describe a family where exome sequencing of a 3-year-old boy with clinical features of Cockayne syndrome (CS) confirmed the diagnosis of CS. He also had a mutation consistent with a pre-symptomatic second disease, multiple endocrine neoplasia type 1 (MEN1), each potentially affecting multiple organ systems, in addition to a poorly defined variant in fumarate hydratase (FH). Genomic sequencing may reveal coexisting pathogenic mutations and variants which complicate clinical interpretation.

Genetic Diagnosis of Cockayne Syndrome

Researchers from the University of Strasbourg investigated whether defective transcription of ATF3 responsive genes is a marker for Cockayne Syndrome (CS).

Two Cockayne Syndrome patients with a novel splice site mutation - clinical and metabolic analyses

Cockayne Syndrome (CS) is a rare autosomal recessive disorder, which leads to neurodegeneration, growth failure and premature aging. Most of the cases are due to mutations in the ERCC6 gene, which encodes the protein CSB. CSB is involved in several functions including DNA repair and transcription. Here we describe two Danish brothers with CS. Both patients carried a novel splice site mutation (c.2382+2T>G), and a previously described nonsense mutation (c.3259C>T, p.Arg1087X) in a biallelic state. Both patients presented the cardinal features of the disease including microcephaly, congenital cataract and postnatal growth failure. In addition, their fibroblasts were hypersensitive to UV irradiation and exhibited increased superoxide levels in comparison to fibroblasts from healthy age and gender matched individuals. Metabolomic analysis revealed a distinctive metabolic profile in cells from the CS patients compared to control cells. Among others, α-ketoglutarate, hydroxyglutarate and certain amino acids (ornithine, proline and glycine) were reduced in the CS patient fibroblasts, whereas glycolytic intermediates (glucose-6-phosphate and pyruvic acid) and fatty acids (palmitic, stearic and myristic acid) were increased. Our data not only provide additional information to the database of CS mutations, but also point towards targets for potential treatment of this devastating disease.

Cochlear implantation in pediatric patients with Cockayne Syndrome

Cockayne Syndrome (CS) is a rare, autosomal recessive disorder characterized by a spectrum of phenotypic abnormalities, including progressive sensorineural hearing loss (SNHL) that involves both peripheral and central components. To date, a single series of CS patients undergoing cochlear implant (CI) placement has been reported; this study reports on additional previously unreported pediatric CI recipients. Subjective benefits were noted early after activation in both patients, and speech perception scores improved over time as well, varying from 42 to 70% (versus 0-12% previously). Thus, we report that cochlear implantation in pediatric patients with CS can be effective in the management of progressive SNHL.

The role of Cockayne Syndrome Protein B in transcription regulation

We investigated the question if CSB (Cockayne Syndrome complementation B) protein actively regulates gene transcription and how mutations in CSB gene affect that regulatory role.

Here we describe how we processed and interpreted ChIP-seq data (deposited in Gene Expression Omnibus with accession number GSE50171) obtained during an investigation of that question, and how this analysis assisted in the generation of hypothesis that were subsequently validated using other types of experiment.

A unified model for the molecular basis of Xeroderma pigmentosum-Cockayne Syndrome

Nucleotide Excision Repair (NER) is a pathway that removes lesions distorting the DNA helix. The molecular basis of the rare diseases Xeroderma pigmentosum (XP) and Cockayne Syndrome (CS) are explained based on the defects happening in 2 NER branches: Global-Genome Repair and Transcription-Coupled Repair, respectively. Nevertheless, both afflictions sporadically occur together, giving rise to XP/CS; however, the molecular basis of XP/CS is not understood very well. Many efforts have been made to clarify why mutations in only 4 NER genes, namely XPB, XPD, XPF and XPG, are the basis of this disease. Effort has also been made to unravel why mutations within these genes lead to XP, XP/CS, or other pathologies. We have recently contributed to the disclosure of this puzzle by characterizing Rad3/XPD mutations in Saccharomyces cerevisiae and human cells. Based on our, and others', observations, we propose a model compatible with all XP/CS cases and the current bibliography.

Cockayne Syndrome group B protein stimulates NEIL2 DNA glycosylase activity

Cockayne Syndrome is a segmental premature aging syndrome, which can be caused by loss of function of the CSB protein. CSB is essential for genome maintenance and has numerous interaction partners with established roles in different DNA repair pathways including transcription coupled nucleotide excision repair and base excision repair. Here, we describe a new interaction partner for CSB, the DNA glycosylase NEIL2. Using both cell extracts and recombinant proteins, CSB and NEIL2 were found to physically interact independently of DNA. We further found that CSB is able to stimulate NEIL2 glycosylase activity on a 5-hydroxyl uracil lesion in a DNA bubble structure substrate in vitro. A novel 4,6-diamino-5-formamidopyrimidine (FapyA) specific incision activity of NEIL2 was also stimulated by CSB. To further elucidate the biological role of the interaction, immunofluorescence studies were performed, showing an increase in cytoplasmic CSB and NEIL2 co-localization after oxidative stress. Additionally, stalling of the progression of the transcription bubble with α-amanitin resulted in increased co-localization of CSB and NEIL2. Finally, CSB knockdown resulted in reduced incision of 8-hydroxyguanine in a DNA bubble structure using whole cell extracts. Taken together, our data supports a biological role for CSB and NEIL2 in transcription associated base excision repair.