Identification of a novel motif in DNA ligases exemplified by DNA ligase IV

DNA ligase IV is an essential protein that functions in DNA non-homologous end-joining, the major mechanism that rejoins DNA double-strand breaks in mammalian cells. LIG4 syndrome represents a human disorder caused by mutations in DNA ligase IV that lead to impaired but not ablated activity. Thus far, five conserved motifs in DNA ligases have been identified. We previously reported G469E as a mutational change in a LIG4 syndrome patient. G469 does not lie in any of the previously reported motifs. A sequence comparison between DNA ligases led us to identify residues 468¿476 of DNA ligase IV as a further conserved motif, designated motif Va, present in eukaryotic DNA ligases. We carried out mutational analysis of residues within motif Va examining the impact on adenylation, double-stranded ligation, and DNA binding. We interpret our results using the DNA ligase I:DNA crystal structure. Substitution of the glycine at position 468 with an alanine or glutamic acid severely compromises protein activity and stability. Substitution of G469 with an alanine or glutamic acid is better tolerated but still impacts upon activity and protein stability. These finding suggest that G468 and G469 are important for protein stability and provide insight into the hypomorphic nature of the G469E mutation identified in a LIG4 syndrome patient. In contrast, residues 470, 473 and 476 within motif Va can be changed to alanine residues without any impact on DNA binding or adenylation activity. Importantly, however, such mutational changes do impact upon double-stranded ligation activity. Considered in light of the DNA ligase I:DNA crystal structure, our findings suggest that residues 470¿476 function as part of a molecular pincer that maintains the DNA in a conformation that is required for ligation

A microfibril assembly assay identifies different mechanisms of dominance underlying Marfan syndrome, stiff skin syndrome and acromelic dysplasias

Fibrillin-1 is the major component of the 10–12 nm diameter extracellular matrix microfibrils. The majority of mutations affecting the human fibrillin-1 gene, FBN1, result in Marfan syndrome (MFS), a common connective tissue disorder characterised by tall stature, ocular and cardiovascular defects. Recently, stiff skin syndrome (SSS) and a group of syndromes known collectively as the acromelic dysplasias, which typically result in short stature, skin thickening and joint stiffness, have been linked to FBN1 mutations that affect specific domains of the fibrillin-1 protein. Despite their apparent phenotypic differences, dysregulation of transforming growth factor β (TGFβ) is a common factor in all of these disorders. Using a newly developed assay to track the secretion and incorporation of full-length, GFP-tagged fibrillin-1 into the extracellular matrix, we investigated whether or not there were differences in the secretion and microfibril assembly profiles of fibrillin-1 variants containing substitutions associated with MFS, SSS or the acromelic dysplasias. We show that substitutions in fibrillin-1 domains TB4 and TB5 that cause SSS and the acromelic dysplasias do not prevent fibrillin-1 from being secreted or assembled into microfibrils, whereas MFS-associated substitutions in these domains result in a loss of recombinant protein in the culture medium and no association with microfibrils. These results suggest fundamental differences in the dominant pathogenic mechanisms underlying MFS, SSS and the acromelic dysplasias, which give rise to TGFβ dysregulation associated with these diseases

Poking the bear: Promoting textbook affordability in the face of a restrictive institutional environment

Librarians and instructional designers formed an informal partnership to promote low-cost textbook solutions in the absence of formal initiatives at a public, four-year institution. Learn how we negotiated institutional barriers such as bookstore contract prohibitions and protected revenue streams. Our case examples describe solutions and workflows undertaken to transform course materials, in addition to activities being pursued to make textbook affordability an institutional priority

Repression of transcription at DNA breaks requires cohesin throughout interphase and prevents genome instability

Cohesin subunits are frequently mutated in cancer, but how they function as tumor suppressors is unknown. Cohesin mediates sister chromatid cohesion, but this is not always perturbed in cancer cells. Here, we identify a previously unknown role for cohesin. We find that cohesin is required to repress transcription at DNA double-strand breaks (DSBs). Notably, cohesin represses transcription at DSBs throughout interphase, indicating that this is distinct from its known role in mediating DNA repair through sister chromatid cohesion. We identified a cancer-associated SA2 mutation that supports sister chromatid cohesion but is unable to repress transcription at DSBs. We further show that failure to repress transcription at DSBs leads to large-scale genome rearrangements. Cancer samples lacking SA2 display mutational patterns consistent with loss of this pathway. These findings uncover a new function for cohesin that provides insights into its frequent loss in cancer

Quality of relationships as predictors of outcomes in people with dementia: a systematic review protocol

INTRODUCTION: Serious adverse outcomes for people with dementia include institutionalisation, hospitalisation, death, development of behavioural and psychiatric symptoms, and reduced quality of life. The quality of the relationship between the person with dementia and their informal/family carer is thought to affect the risk of these outcomes. However, little is known about which aspects of relationship quality are important, or how they affect outcomes for people with dementia. METHODS AND ANALYSIS: This will be a systematic review of the literature. Electronic databases MEDLINE, EMBASE, Web of Science, PsycInfo, the Cochrane Database, ALOIS and OpenGrey will be searched from inception. 2 independent reviewers will screen results for eligibility with standardised criteria. Data will be extracted for relevant studies, and information on the associations between relationship quality and dementia outcomes will be synthesised. Meta-analysis will be performed if possible to calculate pooled effect sizes. Narrative synthesis will be performed if study heterogeneity rules out meta-analysis. ETHICS AND DISSEMINATION: Ethical review is not necessary as this review summarises data from previous studies. Results will be disseminated via peer-reviewed publication. Results will also be disseminated to a patient and public involvement group and an expert panel for their views on the findings and implications for future work. TRIAL REGISTRATION NUMBER: CRD42015020518

Antidepressant and antipsychotic drug prescribing and diabetes outcomes:a systematic review of observational studies

Aims: Psychotropic medication may be associated with adverse effects, including among people with diabetes. We conducted a systematic review of observational studies investigating the association between antidepressant or antipsychotic drug prescribing and type 2 diabetes outcomes. Methods: We systematically searched PubMed, EMBASE, and PsycINFO to 15th August 2022 to identify eligible studies. We used the Newcastle-Ottawa scale to assess study quality and performed a narrative synthesis. Results: We included 18 studies, 14 reporting on antidepressants and four on antipsychotics. There were 11 cohort studies, one self-controlled before and after study, two case-control studies, and four cross-sectional studies, of variable quality with highly heterogeneous study populations, exposure definitions, and outcomes analysed. Antidepressant prescribing may be associated with increased risk of macrovascular disease, whilst evidence on antidepressant and antipsychotic prescribing and glycaemic control was mixed. Few studies reported microvascular outcomes and risk factors other than glycaemic control. Conclusions: Studies of antidepressant and antipsychotic drug prescribing in relation to diabetes outcomes are scarce, with shortcomings and mixed findings. Until further evidence is available, people with diabetes prescribed antidepressants and antipsychotics should receive monitoring and appropriate treatment of risk factors and screening for complications as recommended in general diabetes guidelines

Antidepressant and antipsychotic drug prescribing and diabetes outcomes: A systematic review of observational studies

AIMS: Psychotropic medication may be associated with adverse effects, including among people with diabetes. We conducted a systematic review of observational studies investigating the association between antidepressant or antipsychotic drug prescribing and type 2 diabetes outcomes. METHODS: We systematically searched PubMed, EMBASE, and PsycINFO to 15th August 2022 to identify eligible studies. We used the Newcastle-Ottawa scale to assess study quality and performed a narrative synthesis. RESULTS: We included 18 studies, 14 reporting on antidepressants and four on antipsychotics. There were 11 cohort studies, one self-controlled before and after study, two case-control studies, and four cross-sectional studies, of variable quality with highly heterogeneous study populations, exposure definitions, and outcomes analysed. Antidepressant prescribing may be associated with increased risk of macrovascular disease, whilst evidence on antidepressant and antipsychotic prescribing and glycaemic control was mixed. Few studies reported microvascular outcomes and risk factors other than glycaemic control. CONCLUSIONS: Studies of antidepressant and antipsychotic drug prescribing in relation to diabetes outcomes are scarce, with shortcomings and mixed findings. Until further evidence is available, people with diabetes prescribed antidepressants and antipsychotics should receive monitoring and appropriate treatment of risk factors and screening for complications as recommended in general diabetes guidelines

Five More Massive Binaries in the Cygnus OB2 Association

We present the orbital solutions for four OB spectroscopic binaries, MT145, GSC 03161-00815, 2MASS J20294666+4105083, and Schulte 73, and the partial orbital solution to the B spectroscopic binary, MT372, as part of an ongoing study to determine the distribution of orbital parameters for massive binaries in the Cygnus OB2 Association. MT145 is a new, single-lined, moderately eccentric (e=0.291+/-0.009) spectroscopic binary with period of 25.140+/-0.008 days. GSC 03161-00815 is a slightly eccentric (e=0.10+/-0.01), eclipsing, interacting and double-lined spectroscopic binary with a period of 4.674+/-0.004 days. 2MASS J20294666+4105083 is a moderately eccentric (e=0.273+/-0.002) double-lined spectroscopic binary with a period of 2.884+/-0.001 days. Schulte 73 is a slightly eccentric (e=0.169+/-0.009), double-lined spectroscopic binary with a period of 17.28+/-0.03 days and the first "twin" in our survey with a mass ratio of q=0.99+/-0.02. MT372 is a single-lined, eclipsing system with a period of 2.228 days and low eccentricity (e~0). Of the now 18 known OB binaries in Cyg OB2, 14 have periods and mass ratios. Emerging evidence also shows that the distribution of log(P) is flat and consistent with Oepik's Law.Comment: Accepted to Astronomical Journa