Kinase and channel activity of TRPM6 are co-ordinated by a dimerization motif and pocket interaction

Contains fulltext : 138516.pdf (publisher's version ) (Open Access)Mutations in the gene that encodes the atypical channel-kinase TRPM6 (transient receptor potential melastatin 6) cause HSH (hypomagnesaemia with secondary hypocalcaemia), a disorder characterized by defective intestinal Mg2+ transport and impaired renal Mg2+ reabsorption. TRPM6, together with its homologue TRPM7, are unique proteins as they combine an ion channel domain with a C-terminally fused protein kinase domain. How TRPM6 channel and kinase activity are linked is unknown. Previous structural analysis revealed that TRPM7 possesses a non-catalytic dimerization motif preceding the kinase domain. This interacts with a dimerization pocket lying within the kinase domain. In the present study, we provide evidence that the dimerization motif in TRPM6 plays a critical role in regulating kinase activity as well as ion channel activity. We identify mutations within the TRPM6 dimerization motif (Leu1718 and Leu1721) or dimerization pocket (L1743A, Q1832K, A1836N, L1840A and L1919Q) that abolish dimerization and establish that these mutations inhibit protein kinase activity. We also demonstrate that kinase activity of a dimerization motif mutant can be restored by addition of a peptide encompassing the dimerization motif. Moreover, we observe that mutations that disrupt the dimerization motif and dimerization pocket interaction greatly diminish TRPM6 ion channel activity, in a manner that is independent of kinase activity. Finally, we analyse the impact on kinase activity of ten disease-causing missense mutations that lie outwith the protein kinase domain of TRPM6. This revealed that one mutation lying nearby the dimerization motif (S1754N), found previously to inhibit channel activity, abolished kinase activity. These results provide the first evidence that there is structural co-ordination between channel and kinase activity, which is mediated by the dimerization motif and pocket interaction. We discuss that modulation of this interaction could comprise a major regulatory mechanism by which TRPM6 function is controlled

The effect of two lottery-style incentives on response rates to postal questionnaires in a prospective cohort study in preschool children at high risk of asthma: A randomized trial

Background: In research with long-term follow-up and repeated measurements, quick and complete response to questionnaires helps ensure a study's validity, precision and efficiency. Evidence on the effect of non-monetary incentives on response rates in observational longitudinal research is scarce. Objectives. To study the impact of two strategies to enhance completeness and efficiency in observational cohort studies with follow-up durations of around 2 years. Method and intervention. In a factorial design, 771 children between 2 and 5 years old and their parents participating in a prospective cohort study were randomized to three intervention groups and a control group. Three types of lotteries were run: (i) daytrip tickets for the whole family to a popular amusement park if they returned all postal questionnaires, (ii) 12.50-worth gift vouchers for sending back the questionnaire on time after each questionnaire round and (iii) a combination of (i) and (ii). Main outcome measures. Primary outcome was the proportion of participants who returned all questionnaires without any reminder. Secondary outcomes were '100% returned with or without reminder', 'probability of 100% non-response', 'probability of withdrawal', 'proportion of returned questionnaires' and 'overall number of reminders sent'. Statistical analysis. After testing for interaction between the two lottery interventions, the two trials were analysed separately. We calculated risk differences (RD) and numbers needed to "treat" and their 95% confidence intervals. Results: Daytrip nor voucher intervention had an effect on the proportion of participants who returned all questionnaires (RD -0.01; 95% CI-0.07 - 0.06) and (RD 0.02; 95% CI-0.50 - 0.08), respectively. No effects were found on the secondary outcomes. Conclusion: Our findings do not support the idea that lottery-style incentives lead to more complete response to postal questionnaires in observational cohort studies with repeated data collection and follow-up durations of around 2 years

Predicting asthma in preschool children at high risk presenting in primary care: Development of a clinical asthma prediction score

Background: A setting-specific asthma prediction score for preschool children with wheezing and/or dyspnoea presenting in primary healthcare is needed since existing indices are mainly based on general populations. Aims: To find an optimally informative yet practical set of predictors for the prediction of asthma in preschool children at high risk who present in primary healthcare. Methods: A total of 771 Dutch preschool children at high risk of asthma were followed prospectively until the age of six years. Data on asthma symptoms and environmental conditions were obtained using validated questionnaires and specific IgE was measured. At the age of six years the presence of asthma was assessed based on asthma symptoms, medication, and bronchial hyper-responsiveness. A clinical asthma prediction score (CAPS) was developed using bootstrapped multivariable regression methods. Results: In all, 438 children (56.8%) completed the study; the asthma prevalence at six years was 42.7%. Five parameters optimally predicted asthma: age, family history of asthma or allergy, wheezing-induced sleep disturbances, wheezing in the absence of common colds, and specific IgE. CAPS scores range from 0 to 11 points; scores <3 signified a negative predictive value of 78.4% while scores of ≥7 signified a positive predictive value of 74.3%. Conclusions: We have developed an easy-to-use CAPS for preschool children with symptoms suggesting asthma who present in primary healthcare. After suitable validation, the CAPS may assist in guiding shared decision-making to tailor the need for medical or non-medical interventions. External validation of the CAPS is needed

Asthma beliefs among mothers and children from different ethnic origins living in Amsterdam, the Netherlands

<p>Abstract</p> <p>Background</p> <p>Doctors and patients hold varying beliefs concerning illness and treatment. Patients' and families' explanatory models (EMs) vary according to personality and sociocultural factors. In a multi-ethnic society, it is becoming increasingly significant that doctors understand the different beliefs of their patients in order to improve patient/doctor communication as well as patient adherence to treatment.</p> <p>Methods</p> <p>Twelve focus groups were formed, consisting of 40 children diagnosed with asthma, as well as 28 mothers of these children. These groups included mothers and children of different ethnicities who were living in Amsterdam, the Netherlands. In order to understand the beliefs that both mothers and children hold regarding asthma and its treatment, the explanatory models were analysed and compared.</p> <p>Results</p> <p>Study findings show that mothers and children, regardless of ethnicity and age, have their own EMs. Overall, there is a great deal of uncertainty related to the causes, consequences, problems, and symptoms of asthma and its treatment. It also seems that many concerns and feelings of discomfort are the result of lack of knowledge. For instance, the fact that asthma is not seen as a chronic disease requiring daily intake of an inhaled corticosteroid, but rather as an acute phenomenon triggered by various factors, may be very relevant for clinical practice. This particular belief might suggest an explanation for non-adherent behaviour.</p> <p>Conclusion</p> <p>A thorough understanding of the mothers' and children's beliefs regarding the illness and its treatment is an important aspect in the management of asthma. Gaining an understanding of these beliefs will provide a foundation for a solid clinician-patient/family partnership in asthma care. Although ethnic differences were observed, the similarities between the mothers' and children's beliefs in this multi-ethnic population were striking. In particular, a common belief is that asthma is considered an acute rather than a chronic condition. In addition, there is a lack of knowledge about the course and the self-management of asthma. Health care providers should be aware of these commonly held beliefs, and this information could be shared in educational programs.</p

Patterns of knee osteoarthritis management in general practice:a retrospective cohort study using electronic health records

Objective: This study determined patterns of knee osteoarthritis (OA) management by general practitioners (GPs) using routine healthcare data from Dutch general practices from 2011 to 2019. Design: A retrospective cohort study was conducted using the Integrated Primary Care Information database between 2011 and 2019. Electronic health records (EHRs) of n = 750 randomly selected knee OA patients (with either codified or narrative diagnosis) were reviewed against eligibility criteria and n = 503 patients were included. Recorded information was extracted on GPs’ management from six months before to three years after diagnosis and patterns of management were analysed.Results: An X-ray referral was the most widely recorded management modality (63.2%). The next most widely recorded management modalities were a referral to secondary care (56.1%) and medication prescription or advice (48.3%). Records of recommendation of/referral to other primary care practitioners (e.g. physiotherapists) were found in only one third of the patients. Advice to lose weight was least common (1.2%). Records of medication prescriptions or recommendation of/referral to other primary care practitioners were found more frequently in patients with an X-ray referral compared to patients without, while records of secondary care referrals were found less frequently. Records of an X-ray referral were often found in narratively diagnosed knee OA patients before GPs recorded a code for knee OA in their EHR. Conclusion: These findings emphasize the importance of better implementing non-surgical management of knee OA in general practice and on initiatives for reducing the overuse of X-rays for diagnosing knee OA in general practice.</p

Medical students’ perception of general practice:a cross-sectional survey

Background: An increase in the demand for general practitioners is expected in many countries, but only a minority of medical students consider a career in general practice. More detailed and up-to-date knowledge about medical student’s perception of general practice would be helpful for efforts to encourage medical students to consider a career in general practice. Methods: We performed a cross-sectional single center survey among Dutch medical students to evaluate their perception of general practice at three different stages in their study: Ba1: first-year bachelor students; Ba3: third-year bachelor students; Ma3: third-year master students. The impact of different factors on their attitudes and perceptions was quantified. A multivariate logistic regression was performed with ‘interest in general practice’ as the outcome variable. Results: The median age for Ba1 was 18 (IQR: 18–19) and 71.5% were female, for Ba3 the median age was 20 (IQR: 20–21) and 70.6% were female and for Ma3 the median age was 25 years (IQR: 24–26) and 73.3% were female. On average, 31.2% of the respondents had a migration background. The mean response rate for this study was 77.1%. Of the participating Ba1 students (n = 340) only 22.4% considered working as a GP after medical school; for Ba3 students (n = 231) this percentage was 33.8%, and for Ma3 students (n = 210) it was significantly higher at 70.5%; in the final multivariate model this corresponded to an odds ratio (OR) of 4.3 (95%-CI:2.6–6.9) compared to Ba1 students. The strongest predictor in the final model was the opinion that general practice provides a pleasant working environment (OR 9.5; 95%-CI: 6.2–14.5). Conclusion: This study showed that multiple factors are significantly related to medical students’ interest in general practice. Although students believed that general practice does not have a high status within the medical profession, they acknowledged the social importance and the pleasant working environment of general practice. Knowledge obtained in this study can be used when designing a medical curriculum or a general practice course.</p

Gut microbiota-derived propionate reduces cancer cell proliferation in the liver

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