Acetyl transferase EP300 deficiency leads to chronic replication stress mediated by defective fork protection at stalled replication forks.

Mutations in the epigenetic regulator and global transcriptional activator, E1A binding protein (EP300), is being increasingly reported in aggressive hematological malignancies including adult T-cell leukemia/lymphoma (ATLL). However, the mechanistic contribution of EP300 dysregulation to cancer initiation and progression are currently unknown. Independent inhibition of EP300 in human cells results in the differential expression of genes involved in regulating the cell cycle, DNA replication and DNA damage response. Nevertheless, specific function played by EP300 in DNA replication initiation, progression and replication fork integrity has not been studied. Here, using ATLL cells as a model to study EP300 deficiency and an p300-selective PROTAC degrader, degrader as a pharmacologic tool, we reveal that EP300-mutated cells display prolonged cell cycle kinetics, due to pronounced dysregulations in DNA replication dynamics leading to persistent genomic instability. Aberrant DNA replication in EP300-mutated cells is characterized by elevated replication origin firing due to increased replisome pausing genome-wide. We demonstrate that EP300 deficiency results in nucleolytic degradation of nascently synthesized DNA at stalled forks due to a prominent defect in fork stabilization and protection. This in turn results in the accumulation of single stranded DNA gaps at collapsed replication forks, in EP300-deficient cells. Inhibition of Mre11 nuclease rescues the ssDNA accumulation indicating a dysregulation in downstream mechanisms that restrain nuclease activity at stalled forks. Importantly, we find that the absence of EP300 results in decreased expression of BRCA2 protein expression and a dependency on POLD3-mediated error-prone replication restart mechanisms. The overall S-phase abnormalities observed lead to under-replicated DNA in G2/M that instigates mitotic DNA synthesis. This in turn is associated with mitotic segregation defects characterized by elevated micronuclei formation, accumulation of cytosolic DNA and transmission of unrepaired inherited DNA lesions in the subsequent G1-phase in EP300-deficient cells. We demonstrate that the DNA replication dynamics of EP300-mutated cells ATLL cells recapitulate features of BRCA-deficient cancers. Altogether these results suggest that mutations in EP300 cause chronic DNA replication stress and defective replication fork restart results in persistent genomic instability that underlie aggressive chemo-resistant tumorigenesis in humans.

Systemic corticosteroid use in UK Uveitis practice: results from the ocular inflammation steroid toxicity risk (OSTRICH) study.

OBJECTIVES: To ascertain adherence to an international consensus target of ≤7.5 mg/day of prednisolone for maintenance systemic corticosteroid (CS) prescribing in uveitis and report the frequency of courses of high-dose systemic CS in the UK. METHODS: We conducted a national, multicentre audit of systemic CS prescribing for uveitis at 11 UK sites between November 2018 and March 2019. High-dose CS was defined as (1) maintenance >7.5 mg prednisolone for >3 consecutive months, or (2) >1 course ≥40 mg oral CS or ≥500 mg intravenous (IV) methylprednisolone in the past 12 months. Case notes of patients exceeding threshold CS doses were reviewed by an independent uveitis specialist and judged as avoidable or not, based upon a scoring matrix. RESULTS: Of 667 eligible patients, 285 (42.7%) were treated with oral or IV CS over the preceding 12 months; 96 (33.7%) of these exceeded the threshold for high-dose CS. Twenty-five percent of prescribing in patients on excess CS was judged avoidable; attributed to either prescribing long-term CS without evidence of consideration of alternative strategies, prescribing error or miscommunication. More patients received immunomodulatory therapy (IMT) in the group treated with CS above threshold than below threshold (p < 0.001) but there was no significant difference in doses of IMT. CONCLUSION: 33% of patients had been prescribed excessive corticosteroid when compared to the reference standard. An analysis of decision-making suggests there may be opportunity to reduce excess CS prescribing in 25% of these patients.

Certification of Vision Impairment in Patients with Uveitis Attending a Specialist Clinic.

Purpose: To identify the causes of severe visual loss in a UK uveitis clinic, to suggest means of reducing incidence, and to propose improvement in data collection of vision impairment. Patients and methods: Retrospective case series. Results: Over 128 months, 76 (3.5-4% of patients referred) were certified as vision-impaired or severely vision-impaired. The mean age at registration was 48.4 years, 76% were of working age, and 7% were children. The diagnosis leading most often to registration was sympathetic ophthalmia and the most frequent uveitis complications were secondary cataract (whether or not operated upon) in 62%, chronic cystoid macular edema in 43%, and secondary glaucoma in 28%. Visual loss was often multifactorial. Conclusions: Severe and permanent visual loss in uveitis affects people predominantly of working age. It is probably underreported and a restructuring of the certificate of vision impairment may improve data collection. Early referral to a tertiary center may reduce the incidence of vision impairment.

Uveitis and Juvenile Psoriatic Arthritis or Psoriasis.

PURPOSE: To describe the phenotype of the uveitis that accompanies juvenile psoriatic arthritis or psoriasis. DESIGN: Observational case series. METHODS: Setting: Two university-based referral clinics: 1 in England, 1 in the United States. STUDY POPULATION: Five children with uveitis and psoriatic arthritis and 1 with uveitis and psoriasis Observational Procedure: Retrospective chart review. MAIN OUTCOME MEASURES: Demographics of subjects such as age and sex; description of ocular and joint disease; surgical and other complications; medical treatment. RESULTS: Five of the 6 children in this series had the onset of disease at or before age 6 (P = .0008 compared to expected age of onset for psoriatic arthritis in childhood). All children in this series had an inadequate response to topical corticosteroids. Most of the children were treated with systemic corticosteroids for many months, yet all of them went on to require methotrexate. Therapy with systemic methotrexate did not suffice, as all the patients also required some form of biologic therapy. Five of 6 had surgeries such as vitrectomy, cataract extraction, or a procedure for glaucoma control. CONCLUSIONS: The observations suggest that the uveitis that accompanies juvenile psoriatic arthritis might be a distinct disease that is particularly severe when its onset affects children aged 6 years or younger.

An educational intervention to improve adherence to high-dosage patching regimen for amblyopia: a randomised controlled trial.

BACKGROUND: Previous reports suggest that adherence to patching is a major issue in amblyopia treatment. We tested with an unmasked randomised controlled clinical trial whether an intense educational/motivational intervention improves adherence when a high-dose regime is prescribed. METHODS: 62 children with newly diagnosed amblyopia were randomly allocated into two treatment arms with and without educational/motivational intervention material. Both were prescribed patching 10 h/day, 6 days/week for a fixed period of 12 weeks. The intervention arm received an educational/motivational intervention before patching which included information booklets, video, a cartoon story book, sticker charts and a dedicated session with a researcher. The control arm received the usual clinical information. The primary outcome measure was adherence measured using electronic occlusion dose monitors where a success/failure binary outcome was used to account for participants who dropped out of the study defined as patching >4 h/day. Visual outcome, expressed as percentage visual deficit, was measured as secondary outcome. RESULTS: The intervention increased adherence success rate from 45.2% in the control group to 80.6% in the intervention group (p=0.0027). However, visual outcome was not significantly better in the intervention group (p=0.190). CONCLUSIONS: Our study shows that an intense educational/motivational intervention can improve adherence to patching to high prescribed doses although no significant improvement in visual outcome was observed. TRIALS REGISTRATION NUMBER: ISRCTN05346737 (International Standard Randomised Controlled Trial Number Register).

Autosomal-dominant nystagmus, foveal hypoplasia and presenile cataract associated with a novel PAX6 mutation.

Autosomal-dominant idiopathic infantile nystagmus has been linked to 6p12 (OMIM 164100), 7p11.2 (OMIM 608345) and 13q31-q33 (OMIM 193003). PAX6 (11p13, OMIM 607108) mutations can also cause autosomal-dominant nystagmus, typically in association with aniridia or iris hypoplasia. We studied a large multigenerational white British family with autosomal-dominant nystagmus, normal irides and presenile cataracts. An SNP-based genome-wide analysis revealed a linkage to a 13.4-MB region on chromosome 11p13 with a maximum lod score of 2.93. A mutation analysis of the entire coding region and splice junctions of the PAX6 gene revealed a novel heterozygous missense mutation (c.227C>G) that segregated with the phenotype and is predicted to result in the amino-acid substitution of proline by arginine at codon 76 p.(P76R). The amino-acid variation p.(P76R) within the paired box domain is likely to destabilise the protein due to steric hindrance as a result of the introduction of a polar and larger amino acid. Eye movement recordings showed a significant intrafamilial variability of horizontal, vertical and torsional nystagmus. High-resolution in vivo imaging of the retina using optical coherence tomography (OCT) revealed features of foveal hypoplasia, including rudimentary foveal pit, incursion of inner retinal layers, short photoreceptor outer segments and optic nerve hypoplasia. Thus, this study presents a family that segregates a PAX6 mutation with nystagmus and foveal hypoplasia in the absence of iris abnormalities. Moreover, it is the first study showing detailed characteristics using eye movement recordings of autosomal-dominant nystagmus in a multigenerational family with a novel PAX6 mutation.