MARCKS affects cell motility and response to BTK inhibitors in CLL.

Bruton tyrosine kinase (BTK) inhibitors are highly active drugs for the treatment of chronic lymphocytic leukemia (CLL). To understand the response to BTK inhibitors on a molecular level, we performed (phospho)proteomic analyses under ibrutinib treatment. We identified 3466 proteins and 9184 phosphopeptides (representing 2854 proteins) in CLL cells exhibiting a physiological ratio of phosphorylated serines (pS), threonines (pT), and tyrosines (pY) (pS:pT:pY). Expression of 83 proteins differed between unmutated immunoglobulin heavy-chain variable region (IGHV) CLL (UM-CLL) and mutated IGHV CLL (M-CLL). Strikingly, UM-CLL cells showed higher basal phosphorylation levels than M-CLL samples. Effects of ibrutinib on protein phosphorylation levels were stronger in UM-CLL, especially on phosphorylated tyrosines. The differentially regulated phosphopeptides and proteins clustered in pathways regulating cell migration, motility, cytoskeleton composition, and survival. One protein, myristoylated alanine-rich C-kinase substrate (MARCKS), showed striking differences in expression and phosphorylation level in UM-CLL vs M-CLL. MARCKS sequesters phosphatidylinositol-4,5-bisphosphate, thereby affecting central signaling pathways and clustering of the B-cell receptor (BCR). Genetically induced loss of MARCKS significantly increased AKT signaling and migratory capacity. CD40L stimulation increased expression of MARCKS. BCR stimulation induced phosphorylation of MARCKS, which was reduced by BTK inhibitors. In line with our in vitro findings, low MARCKS expression is associated with significantly higher treatment-induced leukocytosis and more pronounced decrease of nodal disease in patients with CLL treated with acalabrutinib.

miRs-138 and -424 control palmitoylation-dependent CD95-mediated cell death by targeting acyl protein thioesterases 1 and 2 in CLL.

Resistance toward CD95-mediated apoptosis is a hallmark of many different malignancies, as it is known from primary chronic lymphocytic leukemia (CLL) cells. Previously, we could show that miR-138 and -424 are downregulated in CLL cells. Here, we identified 2 new target genes, namely acyl protein thioesterase (APT) 1 and 2, which are under control of both miRs and thereby significantly overexpressed in CLL cells. APTs are the only enzymes known to promote depalmitoylation. Indeed, membrane proteins are significantly less palmitoylated in CLL cells compared with normal B cells. We identified APTs to directly interact with CD95 to promote depalmitoylation, thus impairing apoptosis mediated through CD95. Specific inhibition of APTs by siRNAs, treatment with miRs-138/-424, and pharmacologic approaches restore CD95-mediated apoptosis in CLL cells and other cancer cells, pointing to an important regulatory role of APTs in CD95 apoptosis. The identification of the depalmitoylation reaction of CD95 by APTs as a microRNA (miRNA) target provides a novel molecular mechanism for how malignant cells escape from CD95-mediated apoptosis. Here, we introduce palmitoylation as a novel posttranslational modification in CLL, which might impact on localization, mobility, and function of molecules, survival signaling, and migration.

Young Children and the Creation of a Digital Identity on Social Networking Sites: Scoping Review.

BACKGROUND: There is limited understanding of the concept of the digital identity of young children created through engagement on social networking sites. OBJECTIVE: The objective of this scoping review was to identify key characteristics of the concept of digital identity for children from conception to the age of 8 years on social networking sites. METHODS: This scoping review was conducted using the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines. The key databases searched were EBSCO, Web of Science, ProQuest ERIC, and Scopus. Gray literature sources (National Grey Literature Collection, ProQuest Dissertations and Theses, and Google Scholar) were also searched to identify unpublished studies. Articles were selected if they were published in English and reported data on the digital identity of children in relation to social networking sites. RESULTS: The key terms used in the literature were sharenting, followed by digital footprints and children's identities. Our study revealed 2 approaches to the creation of digital identity: social digital identity and performative digital identity. The articles in this review most commonly used the term sharenting to describe the behavior parents engage in to create digital identities for children on social networking sites. Motivations to post information about children differed among parents; however, the most common reasons were to share with friends and family and create digital archives of childhood photos, termed social digital identity. The second motivation was categorized as performative digital identity. The risk of digital kidnapping and identity theft associated with the creation of digital identities also influenced parents' behaviors. CONCLUSIONS: The creation of a digital identity for children is an emerging concept. Our review develops a deeper understanding of sharenting behaviors that can be used to better support parents and their children in creating a digital identity with children and awareness of the potential future impact. We recommend that future studies explore the perspectives of children as key stakeholders in the creation of their digital identity.

A Novel Approach to Measure Executive Functions in Students: An Evaluation of Two Child-Friendly Apps.

Interest in measurement of children's executive functions has shown a major increase over the past two decades. The present study evaluates two new apps (EYT and eFun) for measuring executive functions in children. The results of this study show that children (aged 5-8) enjoy executive function assessment in the form of games on an iPad. However, only one executive function, EYT working memory, showed significant positive correlations with several types of grades (e.g., English and maths) in primary school students. New, self-assessed, child-friendly executive function measurement tools have the potential to provide future possibilities for teachers to integrate information on cognitive ability into student learning plans.

Clonal dynamics towards the development of venetoclax resistance in chronic lymphocytic leukemia.

Deciphering the evolution of cancer cells under therapeutic pressure is a crucial step to understand the mechanisms that lead to treatment resistance. To this end, we analyzed whole-exome sequencing data of eight chronic lymphocytic leukemia (CLL) patients that developed resistance upon BCL2-inhibition by venetoclax. Here, we report recurrent mutations in BTG1 (2 patients) and homozygous deletions affecting CDKN2A/B (3 patients) that developed during treatment, as well as a mutation in BRAF and a high-level focal amplification of CD274 (PD-L1) that might pinpoint molecular aberrations offering structures for further therapeutic interventions.