Characterization of RIPK3-mediated phosphorylation of the activation loop of MLKL during necroptosis

Mixed lineage kinase domain-like pseudokinase (MLKL) mediates necroptosis by translocating to the plasma membrane and inducing its rupture. The activation of MLKL occurs in a multimolecular complex (the 'necrosome'), which is comprised of MLKL, receptor-interacting serine/threonine kinase (RIPK)-3 (RIPK3) and, in some cases, RIPK1. Within this complex, RIPK3 phosphorylates the activation loop of MLKL, promoting conformational changes and allowing the formation of MLKL oligomers, which migrate to the plasma membrane. Previous studies suggested that RIPK3 could phosphorylate the murine MLKL activation loop at Ser345, Ser347 and Thr349. Moreover, substitution of the Ser345 for an aspartic acid creates a constitutively active MLKL, independent of RIPK3 function. Here we examine the role of each of these residues and found that the phosphorylation of Ser345 is critical for RIPK3-mediated necroptosis, Ser347 has a minor accessory role and Thr349 seems to be irrelevant. We generated a specific monoclonal antibody to detect phospho-Ser345 in murine cells. Using this antibody, a series of MLKL mutants and a novel RIPK3 inhibitor, we demonstrate that the phosphorylation of Ser345 is not required for the interaction between RIPK3 and MLKL in the necrosome, but is essential for MLKL translocation, accumulation in the plasma membrane, and consequent necroptosis.

FZD7 drives in vitro aggressiveness in Stem-A subtype of ovarian cancer via regulation of non-canonical Wnt/PCP pathway

Ovarian cancer (OC) can be classified into five biologically distinct molecular subgroups: epithelial-A (Epi-A), Epi-B, mesenchymal (Mes), Stem-A and Stem-B. Among them, Stem-A expresses genes relating to stemness and is correlated with poor clinical prognosis. In this study, we show that frizzled family receptor 7 (FZD7), a receptor for Wnt signalling, is overexpressed in the Stem-A subgroup. To elucidate the functional roles of FZD7, we used an RNA interference gene knockdown approach in three Stem-A cell lines: CH1, PA1 and OV-17R. Si-FZD7 OC cells showed reduced cell proliferation with an increase in the G0/G1 sub-population, with no effect on apoptosis. The cells also displayed a distinctive morphologic change by colony compaction to become more epithelial-like and polarised with smaller internuclear distances and increased z-axis height. Immunofluorescence (IF) staining patterns of pan-cadherin and β-catenin suggested an increase in cadherin-based cell–cell adhesion in si-FZD7 cells. We also observed a significant rearrangement in the actin cytoskeleton and an increase in tensile contractility in si-FZD7 OC cells, as evident by the loss of stress fibres and the redistribution of phospho-myosin light chain (pMLC) from the sites of cell–cell contacts to the periphery of cell colonies. Furthermore, there was reciprocal regulation of RhoA (Ras homolog family member A) and Rac1 (Ras-related C3 botulinum toxin substrate 1 (Rho family, small GTP-binding protein Rac1)) activities upon FZD7 knockdown, with a significant reduction in RhoA activity and a concomitant upregulation in Rac1 activity. These changes in pMLC and RhoA, as well as the increased TopFlash reporter activities in si-FZD7 cells, suggested involvement of the non-canonical Wnt/planar cell polarity (PCP) pathway. Selected PCP pathway genes (cadherin EGF LAG seven-pass G-type receptor 3 (CELSR3), prickle homolog 4 (Drosophila) (PRICKLE4), dishevelled-associated activator of morphogenesis 1 (DAAM1), profilin 2 (PFN2), protocadherin 9 (PCDH9), protocadherin α1 (PCDHA1), protocadherin β17 pseudogene (PCDHB17), protocadherin β3 (PCDHB3), sprouty homolog 1 (SPRY1) and protein tyrosine kinase 7 (PTK7)) were found to be more highly expressed in Stem-A than non Stem-A subgroup of OC. Taken together, our results suggest that FZD7 might drive aggressiveness in Stem-A OC by regulating cell proliferation, cell cycle progression, maintenance of the Mes phenotype and cell migration via casein kinase 1ɛ-mediated non-canonical Wnt/PCP pathway.

Generation and characterization of mice with null mutation of the chloride intracellular channel 1 gene

CLIC1 belongs to a family of highly conserved and widely expressed intracellular chloride ion channel proteins existing in both soluble and membrane integrated forms. To study the physiological and biological role of CLIC1 in vivo, we undertook conditional gene targeting to engineer Clic1 gene knock-out mice. This represents creation of the first gene knock-out of a vertebrate CLIC protein family member. We first generated a Clic1 Knock-in (Clic1(FN)) allele, followed by Clic1 knock-out (Clic1(-/-)) mice by crossing Clic1(FN) allele with TNAP-cre mice, resulting in germline gene deletion through Cre-mediated recombination. Mice heterozygous or homozygous for these alleles are viable and fertile and appear normal. However, Clic1(-) (/-) mice show a mild platelet dysfunction characterized by prolonged bleeding times and decreased platelet activation in response to adenosine diphosphate stimulation linked to P2Y(12) receptor signaling.

Ministry of health clinical practice guidelines: cancer screening

The Ministry of Health publishes national clinical practice guidelines to provide doctors and patients in Singapore with evidence-based guidance on managing important medical conditions. This article reproduces the introduction and executive summary (with key recommendations from the guidelines) from the Ministry of Health clinical practice guidelines on cancer screening, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website (http://www.moh.gov. sg/mohcorp/publications.aspx?id=24018). The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Timely diagnosis and management of heparin-induced thrombocytopenia in a frequent request, low incidence single centre using clinical 4T's score and particle gel immunoassay

Clinicians must promptly decide which patients suspected of having heparin-induced thrombocytopenia (HIT) warrant a change in anticoagulation. This single-centre series of 246 HIT testing referrals assessed the combination of clinical score (thrombocytopenia, timing, thrombosis, other causes of thrombocytopenia not evident; 4T's), Diamed ID-Heparin-PF4 immunoassay (PaGIA) and 14C Serotonin Release Assay (SRA) to develop a practical and safe diagnostic strategy for HIT. A total of 142/256 (58%) referrals were in patients with a low 4T's score, with 12/246 (5%) in the high scoring group. PaGIA was positive in 24/246 (9.7%) patients, whilst SRA was positive in 9/246 (3.6%). The overall positive predictive value of a positive PaGIA test alone was 37.5%, however this reached 80% for the high scoring group. Both negative PaGIA and low clinical score independently had negative predictive values of 100%. We subsequently developed an algorithm that, when applied to this cohort, would have resulted in 18/246 patients (7%) definitely requiring alternative anticoagulation, whilst a further 7/246 (2.8%) patients would have been considered on an individual basis. Ultimately (based on SRA) this would have resulted in 16/246 (6.5%) patients unnecessarily having a change in their anticoagulation, with 9/246 (3.6%) patients being 'correctly treated'. The combination of 4T's scoring and PaGIA permitted a practical and safe approach to rapid HIT diagnosis and management.

Vitamin D induces innate antibacterial responses in human trophoblasts via an intracrine pathway

The active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)(2)D), is a potent inducer of the antimicrobial protein cathelicidin, CAMP (LL37). In macrophages this response is dependent on intracrine synthesis of 1,25(OH)(2)D from precursor 25-hydroxyvitamin D (25OHD), catalyzed by the enzyme 25-hydroxyvitamin D-1alpha-hydroxylase (CYP27B1). In view of the fact that trophoblastic cells also express abundant CYP27B1, we postulated a similar intracrine pathway for induction of CAMP in the placenta. Analysis of placenta explants, primary cultures of human trophoblast, and the 3A trophoblastic cell line treated with 1,25(OH)(2)D (1-100 nM) revealed dose-dependent induction of CAMP similar to that observed with primary cultures of human macrophages. Also consistent with macrophages, induction of trophoblastic CAMP was enhanced via intracrine conversion of 25OHD to 1,25(OH)(2)D. However, in contrast to macrophages, induction of CAMP by vitamin D in trophoblasts was not enhanced by costimulation with Toll-like receptor ligands, such as lipopolysaccharide. Despite this, exposure to vitamin D metabolites significantly enhanced antibacterial responses in trophoblastic cells: 3A cells infected with Escherichia coli showed decreased numbers of bacterial colony-forming units compared with vehicle-treated controls when treated with 25OHD (49.6% +/- 10.9%) or 1,25(OH)(2)D (45.4% +/- 9.2%), both P < 0.001. Treatment with 25OHD (1-100 nM) or 1,25(OH)(2)D (0.1-10 nM) also protected 3A cells against cell death following infection with E. coli (13.6%-26.9% and 22.3%-40.2% protection, respectively). These observations indicate that 1,25(OH)(2)D can function as an intracrine regulator of CAMP in trophoblasts, and may thus provide a novel mechanism for activation of innate immune responses in the placenta.

Screening for distress in cancer patients: is the distress thermometer a valid measure in the UK and does it measure change over time? A prospective validation study

A prospective validation study was conducted in 171 consenting patients from oncology and palliative care outpatient clinics to validate the Distress Thermometer (DT) against the Hospital Anxiety and Depression Scale (HADS), General Health Questionnaire-12 (GHQ-12) and Brief Symptom Inventory-18 (BSI-18) at baseline, four weeks and eight weeks. Receiver Operating Characteristic analysis was used to examine the sensitivity and specificity of the DT scores against the clinically significant cut-off scores of the criterion measures reporting 95% confidence intervals. Standardised response means were used to compare DT scores with criterion measures over time. For a cut-off of 4 vs 5, sensitivity against HADS was 79%, specificity 81%; against GHQ-12, sensitivity was 63%, specificity 83%; and against BSI-18, sensitivity was 88%, specificity 74%. At both four and eight weeks, DT scores tended to change significantly in the same direction as the criterion measures. Ninety-five percent of patients found completing the DT acceptable. The DT is valid and acceptable for use as a rapid screening instrument for patients in the UK with cancer. Our results indicate that it can be used to monitor change in psychological distress over time, but further work is needed to confirm this.

The use of complementary therapy by men with prostate cancer in the UK

The study aims were to determine the use of complementary therapies (CT) by men with prostate cancer, and to explore factors influencing CT use and attitudes toward CT use. A cross-sectional survey design was used in which a postal questionnaire was mailed to an eligible sample of 405 patients with prostate cancer receiving outpatient treatment in a London teaching hospital. The primary outcomes were the prevalence of CT use and the relationship between CT use and mental health status. Two hundred and ninety-four patients (73%) responded, of whom 25% were using CT. The most frequently used CTs were vitamins, low-fat diets, lycopene and green tea. Multivariate analyses revealed no differences in mental health scores between CT users and non-users. CT users were younger (OR 0.93, 95% CI 0.89-0.97) and were more likely to be receiving conservative management in the form of 'active surveillance' (OR 5.23, 95% CI 1.78-15.41) compared with non-users. Over half of the participants (55%) wanted to learn more about CT. Forty-three per cent of CT users had not informed any doctor about their CT use. Clinicians need to be aware of the prevalence of CT use amongst patients with prostate cancer, considering the potential harm that could be caused by interactions with conventional treatments.

Metabolic acidosis in the critically ill: part 2. Causes and treatment

The correct identification of the cause, and ideally the individual acid, responsible for metabolic acidosis in the critically ill ensures rational management. In Part 2 of this review, we examine the elevated (corrected) anion gap acidoses (lactic, ketones, uraemic and toxin ingestion) and contrast them with nonelevated conditions (bicarbonate wasting, renal tubular acidoses and iatrogenic hyperchloraemia) using readily available base excess and anion gap techniques. The potentially erroneous interpretation of elevated lactate signifying cell ischaemia is highlighted. We provide diagnostic and therapeutic guidance when faced with a high anion gap acidosis, for example pyroglutamate, in the common clinical scenario 'I can't identify the acid--but I know it's there'. The evidence that metabolic acidosis affects outcomes and thus warrants correction is considered and we provide management guidance including extracorporeal removal and fomepizole therapy.