Protein phosphatase 1c associated with the cardiac sodium calcium exchanger1 regulates its activity by dephosphorylating serine 68 phosphorylated phospholemman

The sodium (Na+)-calcium (Ca2+) exchanger 1 (NCX1) is an important regulator of intracellular Ca2+ homeostasis. Serine 68-phosphorylated phospholemman (pSer-68-PLM) inhibits NCX1 activity. In the context of Na+/K+-ATPase (NKA) regulation, pSer-68-PLM is dephosphorylated by protein phosphatase 1 (PP1). PP1 also associates with NCX1; however, the molecular basis of this association is unknown. In this study, we aimed to analyze the mechanisms of PP1 targeting to the NCX1-pSer-68-PLM complex and hypothesized that a direct and functional NCX1-PP1 interaction is a prerequisite for pSer-68-PLM dephosphorylation. Using a variety of molecular techniques, we show that PP1 catalytic subunit (PP1c) co-localized, co-fractionated, and co-immunoprecipitated with NCX1 in rat cardiomyocytes, left ventricle lysates, and HEK293 cells. Bioinformatic analysis, immunoprecipitations, mutagenesis, pulldown experiments, and peptide arrays constrained PP1c anchoring to the K(I/V)FF motif in the first Ca2+ binding domain (CBD) 1 in NCX1. This binding site is also partially in agreement with the extended PP1-binding motif K(V/I)FF-X5–8Φ1Φ2-X8–9-R. The cytosolic loop of NCX1, containing the K(I/V)FF motif, had no effect on PP1 activity in an in vitro assay. Dephosphorylation of pSer-68-PLM in HEK293 cells was not observed when NCX1 was absent, when the K(I/V)FF motif was mutated, or when the PLM- and PP1c-binding sites were separated (mimicking calpain cleavage of NCX1). Co-expression of PLM and NCX1 inhibited NCX1 current (both modes). Moreover, co-expression of PLM with NCX1(F407P) (mutated K(I/V)FF motif) resulted in the current being completely abolished. In conclusion, NCX1 is a substrate-specifying PP1c regulator protein, indirectly regulating NCX1 activity through pSer-68-PLM dephosphorylation

Predictors of high school dropout, anxiety, and depression in genetic generalized epilepsy

Affective disorders are overrepresented in epilepsy, and people with epilepsy may be at risk of dropping out from school. The aim of the present study was to assess factors influencing high school dropout, anxiety, and depression in genetic generalized epilepsy (GGE). One hundred and ten people with GGE aged 19‐40 years underwent a clinical interview, including the Hospital Anxiety and Depression Scale (HADS) questionnaire. Potential predictors of high school dropout were analyzed with logistic regression, and factors influencing total HADS score were analyzed with linear regression. Having felt excluded because of epilepsy was significantly associated with high school dropout (odds ratio 7.80, P = .009), as was total HADS score (odds ratio 1.22, P = .005). If a participant was currently employed or undergoing education, previous high school dropout was less likely (odds ratio 0.07, P = .005). High school dropout was associated with increased current anxiety and depression (β = 0.32, P = .005). Epilepsy severity (current drug resistance, current polytherapy, and active generalized tonic‐clonic seizures) was not associated with high school dropout, nor with total HADS score. The issue of stigma in epilepsy must be thoroughly addressed in comprehensive care and may be as important as seizure control when it comes to education and quality of life

Long-term follow-up with therapeutic drug monitoring of antiepileptic drugs in patients with juvenile myoclonic epilepsy

Background and purpose: Patients with juvenile myoclonus epilepsy (JME) may experience uncontrolled seizures and challenges regarding adherence. Implementation of therapeutic drug monitoring (TDM) may contribute to individualization of the therapy with antiepileptic drugs (AEDs). The purpose of this study was to investigate how the treatment of patientswith JMEis monitored and todemonstrate pharmacokinetic variability withinand between patients with a long-term TDM approach. Method: Retrospective data from patients with JME from the TDM-database at Drammen Hospital and the National Center for Epilepsy in Norway (2007–2018) were included. Results: Data from 80 of 90 patients with JME using AEDs with TDM measurements was included (88%, 49/31 women/men aged 14–39). One third (27, 33%) was seizure free, 19 (24%) had generalized tonic-clonic seizures, and 53 (66%) myoclonic seizures during the last year. The most common AEDs measured included lamotrigine, valproate, and levetiracetam. Long-term TDM demonstrated variability over time expressed as intra-patient median values and inter-patient ranges of 19% (7–47) for valproate, 43% (10–83) for lamotrigine and 35% (6–111) forlevetiracetam. Fifteenpecent (83/563) ofserum concentrations were below the referencerangesand clould be due to variable adherence. Comedication with valproate for lamotrigine and pregnancy contributed to variability. The applicability is illustrated in a case of 10 years’ follow-up in a young woman. Conclusion: There was extensive pharmacokinetic variability of AEDs in and between patients with JME. A longterm TDM approach may contribute to closer monitoring of patients with JME and be used as a practical tool during clinical consultations

Treatment and challenges with antiepileptic drugs in patients with juvenile myoclonic epilepsy

Background: Patients with juvenile myoclonic epilepsy (JME) may have uncontrolled seizures. The purpose of this study was to investigate the use and challenges with antiepileptic drugs (AEDs) and the patients' view of these challenges. Method: A questionnaire about the use of AEDs, adherence to therapy, and quality of life was given to patients with JME recruited from Drammen Hospital. Data regarding AEDs were confirmed from medical records at Drammen Hospital, Norway (2007–2018). Additional clinical interviews were performed, and a mixed method approach was applied. Results: Ninety patients with defined JME diagnosis, 54/36 women/men aged 14–39 (mean: 25) years, were included. Only 29 (33%) were seizure-free.Within the last year, 21% experienced generalized tonic–clonic seizures (GTCS), and 68% hadmyoclonic jerks. Seventy-six (84%) used AEDs, 78% inmonotherapy. A total of 10 AEDswere used;: most commonly valproate (n = 33), lamotrigine (n = 27), and levetiracetam (n = 21). Two-thirds of valproate users were men while all other AEDs were used more in females than in men. Valproate and levetiracetam displayed better efficacy against GTCS than lamotrigine. One-third often/sometimes forgot their medication nonintentionally while 14% had intentional poor adherence. The majority reported good quality of life (76%). No significant correlations between the use of AEDs, use of valproate, poor adherence, quality of life score, and seizure freedom were demonstrated. Half of the patients had serum concentrations measured every year, and two thirds thought this was important. Qualitative interviews elucidated treatment challenges in JME;, adverse effect burden, adherence, and activities of daily life. Conclusion: Despite the use of AEDs in the majority of patients, only one-thirdwere seizure-free. Other challenges included polypharmacy, the use of valproate in women, and variable adherence. This points to a need for closer follow-up in patients with JME