Genetically-induced Redox Stress Occurs in a Yeast Model for Roberts Syndrome

Roberts Syndrome (RBS) is a multi-spectrum developmental disorder characterized by severe limb, craniofacial, and organ abnormalities and often intellectual disabilities. The genetic basis of RBS is rooted in loss-of-function mutations in the essential N-acetyltransferase ESCO2 which is conserved from yeast (Eco1/Ctf7) to humans. ESCO2/Eco1 regulate many cellular processes that impact chromatin structure, chromosome transmission, gene expression, and repair of the genome. The etiology of RBS remains contentious with current models that include transcriptional dysregulation or mitotic failure. Here, we report evidence that supports an emerging model rooted in defective DNA damage responses. First, the results reveal that redox stress is elevated in both eco1 and cohesion factor Saccharomyces cerevisiae mutant cells. Second, we provide evidence that Eco1 and cohesion factors are required for the repair of oxidative DNA damage such that ECO1 and cohesin gene mutations result in reduced cell viability and hyperactivation of DNA damage checkpoints that occur in response to oxidative stress. Moreover, we show that mutation of ECO1 is solely sufficient to induce endogenous redox stress and sensitizes mutant cells to exogenous genotoxic challenges. Remarkably, antioxidant treatment desensitizes eco1 mutant cells to a range of DNA damaging agents, raising the possibility that modulating the cellular redox state may represent an important avenue of treatment for Roberts Syndrome and tumors that bear ESCO2 mutations.

An ever-changing landscape in Roberts syndrome biology: Implications for macromolecular damage

Roberts syndrome (RBS) is a rare developmental disorder that can include craniofacial abnormalities, limb malformations, missing digits, intellectual disabilities, stillbirth, and early mortality. The genetic basis for RBS is linked to autosomal recessive loss-of-function mutation of the establishment of cohesion (ESCO) 2 acetyltransferase. ESCO2 is an essential gene that targets the DNA-binding cohesin complex. ESCO2 acetylates alternate subunits of cohesin to orchestrate vital cellular processes that include sister chromatid cohesion, chromosome condensation, transcription, and DNA repair. Although significant advances were made over the last 20 years in our understanding of ESCO2 and cohesin biology, the molecular etiology of RBS remains ambiguous. In this review, we highlight current models of RBS and reflect on data that suggests a novel role for macromolecular damage in the molecular etiology of RBS.

A case of Roberts syndrome: its ultrasonographic characteristics and genetic diagnosis

Objective: Roberts syndrome is a very rare genetic disease, and it has an autosomal recessive inheritance pattern. It develops as a result of the mutation in ESCO2 gene located in the 8th chromosome. In our study, we aimed to present a case which was found to have Roberts syndrome coexisting with multiple anomalies, particularly skeletal system anomaly, in the 17 weeks of gestation. Case(s): In the fetal ultrasonographic evaluation performed on the pregnant women who referred to our hospital for routine gestational examination in the 17 weeks of gestation, anomalies in the bilateral upper and lower extremities, contracted legs, bilateral cleft palate and lip, intrauterine growth restriction and cardiac anomaly were found in the fetus. Roberts syndrome was considered first with these ultrasonographic findings. The diagnosis of Roberts syndrome was confirmed by cytogenetic and molecular analyses. Early segregation of centromeres and early breaking up of heterochromatic regions near centromeres were found at metaphase stage. By cytogenetic and molecular analyses, homozygous mutation in ESCO2 gene of the fetus and heterozygous mutation in the parents were found. The termination of pregnancy was decided after the genetic consultation with the parents. Physical examination findings and prenatal ultrasound findings after termination were found similar. Conclusion: Many severe skeletal dysplasia cases can be diagnosed ultrasonographically before 20 weeks of gestation. Early diagnosis ensures to take necessary actions for medical support during postnatal period and in terms of labor if pregnancy continues as well as genetic consultation opportunity. If the genetic disease that causes skeletal dysplasia can be identified and parents are found to have this gene, healthy pregnancies can be achieved by obtaining normal embryos via pre-implantation genetic diagnosis in order to prevent the relapse of the disease.

Esco2 and Cohesin Regulate CRL4 Ubiquitin Ligase ddb1 Expression and Thalidomide Teratogenicity

ABSTRACTCornelia de Lange syndrome (CdLS) and Roberts syndrome (RBS) are severe developmental maladies that arise from mutation of cohesin (including SMC3, CdLS) and ESCO2 (RBS). Though ESCO2 activate cohesin, CdLS and RBS etiologies are currently considered non-synonymous and for which pharmacological treatments are unavailable. Here, we identify a unifying mechanism that integrates these genetic maladies to pharmacologically-induced teratogenicity via thalidomide. Our results reveal that Esco2 and cohesin co-regulate a component of CRL4 ubiquitin ligase through which thalidomide exerts teratogenic effects. These findings are the first to link RBS and CdLS to thalidomide teratogenicity and offers new insights into treatments.