A bifunctional kinase-phosphatase module balances mitotic checkpoint strength and kinetochore-microtubule attachment stability.

Two major mechanisms safeguard genome stability during mitosis: the mitotic checkpoint delays mitosis until all chromosomes have attached to microtubules, and the kinetochore-microtubule error-correction pathway keeps this attachment process free from errors. We demonstrate here that the optimal strength and dynamics of these processes are set by a kinase-phosphatase pair (PLK1-PP2A) that engage in negative feedback from adjacent phospho-binding motifs on the BUB complex. Uncoupling this feedback to skew the balance towards PLK1 produces a strong checkpoint, hypostable microtubule attachments and mitotic delays. Conversely, skewing the balance towards PP2A causes a weak checkpoint, hyperstable microtubule attachments and chromosome segregation errors. These phenotypes are associated with altered BUB complex recruitment to KNL1-MELT motifs, implicating PLK1-PP2A in controlling auto-amplification of MELT phosphorylation. In support, KNL1-BUB disassembly becomes contingent on PLK1 inhibition when KNL1 is engineered to contain excess MELT motifs. This elevates BUB-PLK1/PP2A complex levels on metaphase kinetochores, stabilises kinetochore-microtubule attachments, induces chromosome segregation defects and prevents KNL1-BUB disassembly at anaphase. Together, these data demonstrate how a bifunctional PLK1/PP2A module has evolved together with the MELT motifs to optimise BUB complex dynamics and ensure accurate chromosome segregation.

Cyclin B1 scaffolds MAD1 at the kinetochore corona to activate the mitotic checkpoint.

Cyclin B:CDK1 is the master kinase regulator of mitosis. We show here that, in addition to its kinase functions, mammalian Cyclin B also scaffolds a localised signalling pathway to help preserve genome stability. Cyclin B1 localises to an expanded region of the outer kinetochore, known as the corona, where it scaffolds the spindle assembly checkpoint (SAC) machinery by binding directly to MAD1. In vitro reconstitutions map the key binding interface to a few acidic residues in the N-terminal region of MAD1, and point mutations in this sequence abolish MAD1 corona localisation and weaken the SAC. Therefore, Cyclin B1 is the long-sought-after scaffold that links MAD1 to the corona, and this specific pool of MAD1 is needed to generate a robust SAC response. Robustness arises because Cyclin B1:MAD1 localisation loses dependence on MPS1 kinase after the corona has been established, ensuring that corona-localised MAD1 can still be phosphorylated when MPS1 activity is low. Therefore, this study explains how corona-MAD1 generates a robust SAC signal, and it reveals a scaffolding role for the key mitotic kinase, Cyclin B1:CDK1, which ultimately helps to inhibit its own degradation.

Can we improve the management of inoperable malignant bowel obstruction? Results of a feasibility study of elemental diet as an alternative to parenteral nutrition in patients with advanced gynaecological cancer.

PURPOSE: Nutrition support in inoperable bowel obstruction (IBO) remains challenging. Parenteral nutrition (PN) is recommended if the prognosis is > 2 months. An elemental diet (ED) is licensed for strictures in Crohn's disease but has not been used in malignant bowel obstruction. The aim of this study was to evaluate the use of ED in patients with IBO and provide a proof of concept of ED as an acceptable feeding option. METHODS: This was a mixed-methods single-arm feasibility study. The primary endpoint was to provide a 'proof of concept' of ED as an acceptable feeding option for patients with IBO. Secondary endpoints included taste acceptability, incidences of vomiting and pain, the proportion of women who tolerated ED, the number of cartons drunk, quality of life (QOL) and the number of women treated with chemotherapy. Patients (> 18 years) with CT-confirmed IBO who could tolerate 500 ml of liquid in 24 h remained on the trial for 2 weeks. RESULTS: A total of 29 patients were recruited; of those, 19 contributed to the analysis for the primary endpoint; 13 (68.4%) participants tolerated the ED; 26 patients contributed to MSAS and EORTC QLQ questionnaires at baseline to allow for the assessment of symptoms. At the start of the study, 18 (69%) of patients experienced vomiting, reducing to 4 (25%) by the end of day 15 of the study; 24 (92%) of patients reported pain at consent, reducing to 12 (75%) by the end of day 15. QOL scores improved from 36.2 (95% CI 27.7-44.7) at baseline to 53.1 (95% CI 40.3-66) at the end of day 15; 16 (84%) participants commenced chemotherapy within the first week of starting ED. The number of cartons across all participants showed a median of 1.3 cartons per day (range 0.8 to 2.5). CONCLUSION: ED is well tolerated by patients with IBO caused by gynaecological malignancies and may have a positive effect on symptom burden and QOL.

Atypical APC/C-dependent degradation of Mcl-1 provides an apoptotic timer during mitotic arrest.

The initiation of apoptosis in response to the disruption of mitosis provides surveillance against chromosome instability. Here, we show that proteolytic destruction of the key regulator Mcl-1 during an extended mitosis requires the anaphase-promoting complex or cyclosome (APC/C) and is independent of another ubiquitin E3 ligase, SCFFbw7 Using live-cell imaging, we show that the loss of Mcl-1 during mitosis is dependent on a D box motif found in other APC/C substrates, while an isoleucine-arginine (IR) C-terminal tail regulates the manner in which Mcl-1 engages with the APC/C, converting Mcl-1 from a Cdc20-dependent and checkpoint-controlled substrate to one that is degraded independently of checkpoint strength. This mechanism ensures a relatively slow but steady rate of Mcl-1 degradation during mitosis and avoids its catastrophic destruction when the mitotic checkpoint is satisfied, providing an apoptotic timer that can distinguish a prolonged mitotic delay from normal mitosis. Importantly, we also show that inhibition of Cdc20 promotes mitotic cell death more effectively than loss of APC/C activity through differential effects on Mcl-1 degradation, providing an improved strategy to kill cancer cells.

Multinational Association of Supportive Care in Cancer (MASCC) expert opinion/guidance on the use of clinically assisted nutrition in patients with advanced cancer.

PURPOSE: The pro vision of clinically assisted nutrition (CAN) in patients with advanced cancer is controversial, and there is a paucity of specific guidance, and so a diversity in clinical practice. Consequently, the Palliative Care Study Group of the Multinational Association of Supportive Care in Cancer (MASCC) formed a Subgroup to develop evidence-based guidance on the use CAN in patients with advanced cancer. METHODS: This guidance was developed in accordance with the MASCC Guidelines Policy. A search strategy for Medline was developed, and the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials were explored for relevant reviews/trials respectively. The outcomes of the review were categorised by the level of evidence, and a "category of guideline" based on the level of evidence (i.e. "recommendation", "suggestion", or "no guideline possible"). RESULTS: The Subgroup produced 11 suggestions, and 1 recommendation (due to the paucity of evidence). These outcomes relate to assessment of patients, indications for CAN, contraindications for CAN, procedures for initiating CAN, and re-assessment of patients. CONCLUSIONS: This guidance provides a framework for the use of CAN in advanced cancer, although every patient needs individualised management.

Phosphorylation of XIAP by CDK1-cyclin-B1 controls mitotic cell death.

Regulation of cell death is crucial for the response of cancer cells to drug treatments that cause arrest in mitosis, and is likely to be important for protection against chromosome instability in normal cells. Prolonged mitotic arrest can result in cell death by activation of caspases and the induction of apoptosis. Here, we show that X-linked inhibitor of apoptosis (XIAP) plays a key role in the control of mitotic cell death. Ablation of XIAP expression sensitises cells to prolonged mitotic arrest caused by a microtubule poison. XIAP is stable during mitotic arrest, but its function is controlled through phosphorylation by the mitotic kinase CDK1-cyclin-B1 at S40. Mutation of S40 to a phosphomimetic residue (S40D) inhibits binding to activated effector caspases and abolishes the anti-apoptotic function of XIAP, whereas a non-phosphorylatable mutant (S40A) blocks apoptosis. By performing live-cell imaging, we show that phosphorylation of XIAP reduces the threshold for the onset of cell death in mitosis. This work illustrates that mitotic cell death is a form of apoptosis linked to the progression of mitosis through control by CDK1-cyclin-B1.

Prenatal diagnosis and clinical implications of an apparently isolated right aortic arch.

OBJECTIVE: To define the associations of a prenatally diagnosed, apparently isolated right aortic arch (RAA) with chromosomal or genetic abnormalities and tracheal compression. METHODS: This was a retrospective study of apparently isolated RAA assessed by fetal cardiologists and fetal medicine specialists at Kings College Hospital, London between 2000 and 2017. RESULTS: The search identified 138 cases of apparently isolated RAA. Invasive testing was performed in 75, and chromosomal or genetic anomalies were identified in 16 (22%), and the most common was 22q11 microdeletion. An aberrant left subclavian artery was seen in 51% of cases. Symptoms of a vascular ring were present in 24 of 97 (25%) children who were reviewed after birth. Bronchoscopy was performed in 33 children, and significant tracheal compression was diagnosed in 28, including 18 of 19 symptomatic and 10 of 14 asymptomatic children. CONCLUSIONS: An apparently isolated RAA is associated with a high incidence of chromosomal or genetic abnormalities and a high incidence of tracheal compression in symptomatic and asymptomatic patients. Prenatal counselling for genetic associations and postnatal airway assessment in the context of the vascular anatomy is recommended.

Phosphorylation of Mcl-1 by CDK1-cyclin B1 initiates its Cdc20-dependent destruction during mitotic arrest.

The balance between cell cycle progression and apoptosis is important for both surveillance against genomic defects and responses to drugs that arrest the cell cycle. In this report, we show that the level of the human anti-apoptotic protein Mcl-1 is regulated during the cell cycle and peaks at mitosis. Mcl-1 is phosphorylated at two sites in mitosis, Ser64 and Thr92. Phosphorylation of Thr92 by cyclin-dependent kinase 1 (CDK1)-cyclin B1 initiates degradation of Mcl-1 in cells arrested in mitosis by microtubule poisons. Mcl-1 destruction during mitotic arrest requires proteasome activity and is dependent on Cdc20/Fizzy, which mediates recognition of mitotic substrates by the anaphase-promoting complex/cyclosome (APC/C) E3 ubiquitin ligase. Stabilisation of Mcl-1 during mitotic arrest by mutation of either Thr92 or a D-box destruction motif inhibits the induction of apoptosis by microtubule poisons. Thus, phosphorylation of Mcl-1 by CDK1-cyclin B1 and its APC/C(Cdc20)-mediated destruction initiates apoptosis if a cell fails to resolve mitosis. Regulation of apoptosis, therefore, is linked intrinsically to progression through mitosis and is governed by a temporal mechanism that distinguishes between normal mitosis and prolonged mitotic arrest.

Early prehabilitation in suspected locally advanced and metastatic lung cancer.

OBJECTIVES: The most common treatment for locally advanced and metastatic lung cancer is best supportive care. Patients with lung cancer are often comorbid with a high symptom burden. We wanted to assess whether early prehabilitation was feasible in patients with likely lung cancer. METHODS: Patients were offered prehabilitation if they were attending the new patient respiratory clinic, had a CT scan suggesting stage III or IV lung cancer and undergoing further investigations. Patients receiving palliative care were ineligible. All prehabilitation patients were referred to a palliative medicine physician, registered dietitian and rehabilitation physiotherapist. RESULTS: 50 patients underwent prehabilitation between June 2021 and August 2022. The median age was 72 years (range 54-89 years). 48 patients had lung cancer. 84% of patients attended all three interventions.Half of the palliative care consultations focused on pain. Half of the patients seen had a change in medication. 25% of patients' weights were stable, 32% required a food-first strategy and 33% required oral nutritional supplements. 57% of patients discussed managing breathlessness with the physiotherapist. CONCLUSIONS: Early prehabilitation is feasible alongside the investigation of locally advanced and metastatic lung cancer. Further work will aim to assess its impact on admission to the hospital, survival and treatment rates.

Early prehabilitation reduces admissions and time in hospital in patients with newly diagnosed lung cancer.

OBJECTIVES: Lung cancer is the leading cause of cancer death in the UK. Prehabilitation aims to maximise patient fitness and minimise the negative impact of anticancer treatment. What constitutes prehabilitation before non-surgical anticancer treatment is not well established. We present data from a pilot project of Early prehabilitation In lung Cancer. METHODS: All new patients with likely advanced lung cancer were offered prehabilitation at respiratory clinic, if fit for further investigation. Prehabilitation included assessment and appropriate intervention from a consultant in palliative medicine, registered dietitian and rehabilitation physiotherapist. Four objective endpoints were identified, namely admissions to hospital, time spent in the hospital, treatment rates and overall survival. Outcomes were to be compared with 178 prehab eligible historical controls diagnosed from 2019 to 2021. RESULTS: From July 2021 to June 2023, 65 patients underwent prehabilitation and 72% of patients underwent all 3 interventions. 54 patients had a stage 3 or 4 lung cancer. In the prehab group, fewer patients attended Accident and Emergency (31.5 vs 37.4 attendances per 100 patients) and fewer were admitted (51.9 vs 67.9) when compared with historical controls. Those receiving prehab spent a lot less time in the hospital (129.7 vs 543.5 days per 100 patients) with shorter admissions (2.5 vs 8 days). Systemic anticancer treatment rates increased in the short term but were broadly similar overall. Median survival was higher in the prehabilitation group (0.73 vs 0.41 years, p=0.046). CONCLUSIONS: Early prehabilitation appears to reduce time spent in the hospital. It may improve survival. Further work is required to understand its full effect on treatment rates.

Nutritional status and symptom burden in advanced non-small cell lung cancer: results of the dietetic assessment and intervention in lung cancer (DAIL) trial.

INTRODUCTION: European Society for Clinical Nutrition and Metabolism guidelines recommend that patients with cancer should be screened for malnutrition at diagnosis. The dietetic assessment and intervention in lung cancer study investigated the nutritional status of patients with non-small cell lung cancer (NSCLC) and the need for dietetic intervention. METHODS: In this observational cohort pilot study, patients with stage 3b and 4 NSCLC were assessed prior to starting first line systemic anticancer therapy (SACT) with a range of measurements and questionnaires. We report the outcomes related to the Patient Generated Subjective Global Assessment tool (PG-SGA), RESULTS: 96 patients were consented between April 2017 and August 2019. The PG-SGA identified that 78% of patients required specialist nutritional advice; with 52% patients having a critical need for dietetic input and symptom management. Results were dominated by symptom scores. As a screening test, one or more symptoms or recent weight loss history had a sensitivity of 88% (95% CI 78.44% to 94.36%) and specificity of 95.24% (95% CI 76.18% to 99.88%) for need for dietetic intervention. CONCLUSION: A large proportion of patients with NSCLC have a high symptom burden and are at risk of malnutrition prior to starting SACT and would benefit from dietetic review. It is imperative that oncologists and healthcare professionals discuss weight loss history and symptoms with lung cancer patients to correct nutritional deficiencies and resolve symptoms prior to starting treatment.

A multi-center prospective study of plant-based nutritional support in adult community-based patients at risk of disease-related malnutrition.

Introduction: There is an emerging need for plant-based, vegan options for patients requiring nutritional support. Methods: Twenty-four adults at risk of malnutrition (age: 59 years (SD 18); Sex: 18 female, 6 male; BMI: 19.0 kg/m2 (SD 3.3); multiple diagnoses) requiring plant-based nutritional support participated in a multi-center, prospective study of a (vegan suitable) multi-nutrient, ready-to-drink, oral nutritional supplement (ONS) [1.5 kcal/mL; 300 kcal, 12 g protein/200 mL bottle, mean prescription 275 mL/day (SD 115)] alongside dietary advice for 28 days. Compliance, anthropometry, malnutrition risk, dietary intake, appetite, acceptability, gastrointestinal (GI) tolerance, nutritional goal(s), and safety were assessed. Results: Patients required a plant-based ONS due to personal preference/variety (33%), religious/cultural reasons (28%), veganism/reduce animal-derived consumption (17%), environmental/sustainability reasons (17%), and health reasons (5%). Compliance was 94% (SD 16). High risk of malnutrition ('MUST' score ≥ 2) reduced from 20 to 16 patients (p = 0.046). Body weight (+0.6 kg (SD 1.2), p = 0.02), BMI (+0.2 kg/m2 (SD 0.5), p = 0.03), total mean energy (+387 kcal/day (SD 416), p < 0.0001) and protein intake (+14 g/day (SD 39), p = 0.03), and the number of micronutrients meeting the UK reference nutrient intake (RNI) (7 vs. 14, p = 0.008) significantly increased. Appetite (Simplified Nutritional Appetite Questionnaire (SNAQ) score; p = 0.13) was maintained. Most GI symptoms were stable throughout the study (p > 0.06) with no serious adverse events related. Discussion: This study highlights that plant-based nutrition support using a vegan-suitable plant-based ONS is highly complied with, improving the nutritional outcomes of patients at risk of malnutrition.

Early dietitian referral in lung cancer: use of machine learning.

OBJECTIVES: The Dietetic Assessment and Intervention in Lung Cancer (DAIL) study was an observational cohort study. It triaged the need for dietetic input in patients with lung cancer, using questionnaires with 137 responses. This substudy tested if machine learning could predict need to see a dietitian (NTSD) using 5 or 10 measures. METHODS: 76 cases from DAIL were included (Royal Surrey NHS Foundation Trust; RSH: 56, Frimley Park Hospital; FPH 20). Univariate analysis was used to find the strongest correlates with NTSD and 'critical need to see a dietitian' CNTSD. Those with a Spearman correlation above ±0.4 were selected to train a support vector machine (SVM) to predict NTSD and CNTSD. The 10 and 5 best correlates were evaluated. RESULTS: 18 and 13 measures had a correlation above ±0.4 for NTSD and CNTSD, respectively, producing SVMs with 3% and 7% misclassification error. 10 measures yielded errors of 7% (NTSD) and 9% (CNTSD). 5 measures yielded between 7% and 11% errors. SVM trained on the RSH data and tested on the FPH data resulted in errors of 20%. CONCLUSIONS: Machine learning can predict NTSD producing misclassification errors <10%. With further work, this methodology allows integrated early referral to a dietitian independently of a healthcare professional.

Inhibition of caspase-9 through phosphorylation at Thr 125 by ERK MAPK.

Many pro-apoptotic signals activate caspase-9, an initiator protease that activates caspase-3 and downstream caspases to initiate cellular destruction. However, survival signals can impinge on this pathway and suppress apoptosis. Activation of the Ras-Raf-MEK-ERK mitogen-activated protein kinase (MAPK) pathway is associated with protection of cells from apoptosis and inhibition of caspase-3 activation, although the targets are unknown. Here, we show that the ERK MAPK pathway inhibits caspase-9 activity by direct phosphorylation. In mammalian cell extracts, cytochrome c-induced activation of caspases-9 and -3 requires okadaic-acid-sensitive protein phosphatase activity. The opposing protein kinase activity is overcome by treatment with the broad-specificity kinase inhibitor staurosporine or with inhibitors of MEK1/2. Caspase-9 is phosphorylated at Thr 125, a conserved MAPK consensus site targeted by ERK2 in vitro, in a MEK-dependent manner in cells stimulated with epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA). Phosphorylation at Thr 125 is sufficient to block caspase-9 processing and subsequent caspase-3 activation. We suggest that phosphorylation and inhibition of caspase-9 by ERK promotes cell survival during development and tissue homeostasis. This mechanism may also contribute to tumorigenesis when the ERK MAPK pathway is constitutively activated.

Challenges in the diagnosis of fetal non-chromosomal abnormalities at 11-13 weeks.

OBJECTIVE: To examine the performance of the 11-13 weeks scan in detecting non-chromosomal abnormalities. METHODS: Prospective first-trimester screening study for aneuploidies, including basic examination of the fetal anatomy, in 45 191 pregnancies. Findings were compared to those at 20-23 weeks and postnatal examination. RESULTS: Aneuploidies (n = 332) were excluded from the analysis. Fetal abnormalities were observed in 488 (1.1%) of the remaining 44 859 cases; 213 (43.6%) of these were detected at 11-13 weeks. The early scan detected all cases of acrania, alobar holoprosencephaly, exomphalos, gastroschisis, megacystis and body stalk anomaly, 77% of absent hand or foot, 50% of diaphragmatic hernia, 50% of lethal skeletal dysplasias, 60% of polydactyly, 34% of major cardiac defects, 5% of facial clefts and 14% of open spina bifida, but none of agenesis of the corpus callosum, cerebellar or vermian hypoplasia, echogenic lung lesions, bowel obstruction, most renal defects or talipes. Nuchal translucency (NT) was above the 95th percentile in 34% of fetuses with major cardiac defects. CONCLUSION: At 11-13 weeks some abnormalities are always detectable, some can never be and others are potentially detectable depending on their association with increased NT, the phenotypic expression of the abnormality with gestation and the objectives set for such a scan.

Contribution of ductus venosus Doppler in first-trimester screening for major cardiac defects.

OBJECTIVE: To determine whether assessment of ductus venosus flow at 11-13 weeks' gestation improves the detection rate of cardiac defects achieved by screening with nuchal translucency (NT) thickness. METHODS: Prospective first-trimester screening for aneuploidies, including measurement of fetal NT and assessment of ductus venosus flow. The performance of different combinations of increased fetal NT and abnormal blood flow in the ductus venosus in screening for major cardiac defects was examined. RESULTS: The study population of euploid fetuses included 85 cases with major cardiac defects and 40,905 with no cardiac defects. The fetal NT was above the 95th and above the 99th centile in 30 (35.3%) and 18 (21.2%) of the fetuses with cardiac defects, respectively, and in 1,956 (4.8%) and 290 (0.7%) of those without cardiac defects, respectively. Reversed a-wave was observed in 24 (28.2%) of the fetuses with cardiac defects and in 856 (2.1%) of those with no cardiac defects. Specialist fetal echocardiography for cases with NT above the 99th centile and those with reversed a-wave, irrespective of NT, would detect 38.8% of major cardiac defects at an overall false- positive rate of 2.7%. CONCLUSIONS: Assessment of ductus venosus flow improves the performance of NT screening for cardiac defects.

Reference Ranges for Pulsed-Wave Doppler of the Fetal Cardiac Inflow and Outflow Tracts from 13 to 36 Weeks' Gestation.

BACKGROUND: Doppler assessment of ventricular filling and outflow tract velocities is an integral part of fetal echocardiography, to assess diastolic function, systolic function, and outflow tract obstruction. There is a paucity of prospective data from a large sample of normal fetuses in the published literature. The authors report reference ranges for pulsed-wave Doppler flow of the mitral valve, tricuspid valve, aortic valve, and pulmonary valve, as well as heart rate, in a large number of fetuses prospectively examined at a single tertiary fetal cardiology center. METHODS: The study population comprised 7,885 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective pulsed-wave Doppler blood flow measurements were taken of the mitral, tricuspid, aortic, and pulmonary valves. The fetal heart rate was recorded at the time of each assessment. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. RESULTS: The measurement for each cardiac Doppler measurement was expressed as a Z score (difference between observed and expected values divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac inflow and outflow tracts. CONCLUSIONS: This study establishes reference ranges for fetal cardiac Doppler measurements and heart rate between 13 to 36 weeks' gestation that may be useful in clinical practice.

Fetal cardiac scanning today.

The ability to examine the structure of the fetal heart in real-time started over 30 years ago now. The field has seen very great advances since then, both in terms of technical improvements in ultrasound equipment and in dissemination of operator skills. A great deal has been learnt about normal cardiac function in the human fetus throughout gestation and how it is affected by pathologies of pregnancy. There is increasing recognition of abnormal heart structure during routine obstetric scanning, allowing referral for specialist diagnosis and counselling. It is now possible to make accurate diagnosis of cardiac malformations as early as 12 weeks of gestation. Early diagnosis of a major cardiac malformation in the fetus can provide the parents with a comprehensive prognosis, enabling them to make the most informed choice about the management of the pregnancy.

Prevalence of increased nuchal translucency in fetuses with congenital cardiac disease and a normal karyotype.

OBJECTIVES: Our aims were to estimate the prevalence of increased nuchal translucency in fetuses with a normal karyotype that were subsequently diagnosed with congenital cardiac disease on fetal echocardiography, and to assess whether there is a link between increased nuchal translucency and specific congenital cardiac malformations. METHODS: We reviewed all patients referred to King's College Hospital and the Evelina Children's Hospital in London for fetal echocardiography between January 1998 and December 2007. We investigated the proportion of chromosomally normal fetuses with congenitally malformed hearts in which nuchal thickness was increased, both overall and with specific defects. RESULTS: We identified 2133 fetuses with congenital cardiac disease by prenatal echocardiography. Of those, 707 were excluded due to abnormal karyotype, and 690 were excluded due to unknown karyotype. The remaining 736 were eligible for inclusion. Among 481 fetuses with documented congenital cardiac disease and normal chromosomes, making up 23% of the overall cohort, 224 had increased nuchal thickness defined as equal or greater than 2.5 millimetres, this being 0.47 of the inclusive cohort, with 95% confidence intervals from 0.42 to 0.51. These proportions were significantly higher than the expected proportion of the normal population, which was 0.05 (p < 0.001). The only diagnosis for which the proportion of fetuses with nuchal translucency measurement equal or greater than 2.5 millimetres was higher than the others was atrioventricular septal defect, with 0.62 of this cohort having abnormal values, with 95% confidence intervals from 0.47 to 0.77 (p = 0.038). CONCLUSION: We found that nearly half of prenatally diagnosed fetuses with congenitally malformed hearts, when examined ultrasonically in the first or early-second trimester, had increased nuchal thickness. We recommend, therefore, referral of all fetuses with increased nuchal translucency for fetal echocardiography.

Division of labour between PP2A-B56 isoforms at the centromere and kinetochore.

PP2A-B56 is a serine/threonine phosphatase complex that regulates several major mitotic processes, including sister chromatid cohesion, kinetochore-microtubule attachment and the spindle assembly checkpoint. We show here that these key functions are divided between different B56 isoforms that localise to either the centromere or kinetochore. The centromeric isoforms rely on a specific interaction with Sgo2, whereas the kinetochore isoforms bind preferentially to BubR1 and other proteins containing an LxxIxE motif. In addition to these selective binding partners, Sgo1 helps to anchor PP2A-B56 at both locations: it collaborates with BubR1 to maintain B56 at the kinetochore and it helps to preserve the Sgo2/B56 complex at the centromere. A series of chimaeras were generated to map the critical region in B56 down to a small C-terminal loop that regulates the key interactions and defines B56 localisation. Together, this study describes how different PP2A-B56 complexes utilise isoform-specific interactions to control distinct processes during mitosis.