ANKRD54 preferentially selects Bruton's Tyrosine Kinase (BTK) from a Human Src-Homology 3 (SH3) domain library

Bruton's Tyrosine Kinase (BTK) is a cytoplasmic protein tyrosine kinase with a fundamental role in B-lymphocyte development and activation. The nucleocytoplasmic shuttling of BTK is specifically modulated by the Ankyrin Repeat Domain 54 (ANKRD54) protein and the interaction is known to be exclusively SH3-dependent. To identify the spectrum of the ANKRD54 SH3-interactome, we applied phage-display screening of a library containing all the 296 human SH3 domains. The BTK-SH3 domain was the prime interactor. Quantitative western blotting analysis demonstrated the accuracy of the screening procedure. Revealing the spectrum and specificity of ANKRD54-interactome is a critical step toward functional analysis in cells and tissues.Peer reviewe

Novel Coronin7 interactions with Cdc42 and N-WASP regulate actin organization and Golgi morphology

YesThe contribution of the actin cytoskeleton to the unique architecture of the Golgi complex is manifold. An important player in this process is Coronin7 (CRN7), a Golgi-resident protein that stabilizes F-actin assembly at the trans-Golgi network (TGN) thereby facilitating anterograde trafficking. Here, we establish that CRN7-mediated association of F-actin with the Golgi apparatus is distinctly modulated via the small Rho GTPase Cdc42 and N-WASP. We identify N-WASP as a novel interaction partner of CRN7 and demonstrate that CRN7 restricts spurious F-actin reorganizations by repressing N-WASP ‘hyperactivity’ upon constitutive Cdc42 activation. Loss of CRN7 leads to increased cellular F-actin content and causes a concomitant disruption of the Golgi structure. CRN7 harbours a Cdc42- and Rac-interactive binding (CRIB) motif in its tandem β-propellers and binds selectively to GDP-bound Cdc42N17 mutant. We speculate that CRN7 can act as a cofactor for active Cdc42 generation. Mutation of CRIB motif residues that abrogate Cdc42 binding to CRN7 also fail to rescue the cellular defects in fibroblasts derived from CRN7 KO mice. Cdc42N17 overexpression partially rescued the KO phenotypes whereas N-WASP overexpression failed to do so. We conclude that CRN7 spatiotemporally influences F-actin organization and Golgi integrity in a Cdc42- and N-WASP-dependent manner.This work was supported by SFB 670 and DFG NO 113/22. K.B. was supported by a fellowship from the NRW International Graduate School “From Embryo to Old Age: the Cell Biology and Genetics of Health and Disease” (IGSDHD), Cologne

Using Slack for computer-mediated communication to support higher education students’ peer interactions during Master’s thesis seminar

Our study contributes to the research on computer-mediated communication in higher education by experimenting a modern communication tool called Slack. In particular, we consider using Slack to support students’ peer interactions during Master’s thesis work. For this purpose, we designed a case study that was executed in a Master’s thesis seminar course. During the course, all out-of-class communication was carried out by using Slack, instead of e-mails or learning management systems. After the course, we used a questionnaire to investigate how the students perceived Slack for asking for assistance, their intention to use Slack, and Slack’s ease of use. Furthermore, the questionnaire asked feedback about challenges that the students found in slack. To examine the students’ peer support in Slack, we analysed the messages in the course’s public discussion channels. We investigated opportunities and challenges of Slack from instructional perspective by conducting an auto-ethnographic data collection. Our analysis revealed that the students perceived Slack as an easy-to-use communication tool with a low threshold of asking questions. The students also expressed high intentions to use Slack in the future. However, the students were worried of information overload in Slack, frustrated with decentralisation of communication tools in higher education, and cautious of using communication tools that are not officially supported by the university. The students’ interactions were assigned to three categories: practical, technical, and thesis-related. Analysis of these categories revealed that the students were able to explicate and solve issues in Slack, but the issues were only related to practical and technical problems, instead of actual Master’s thesis writing. The teacher perceived that Slack enhanced bi-directional communication with the students, but faced issues related to file management and user authentication. The results implicate that developing an alternative for Slack from educational premises could be more useful than a product that is not originally developed for pedagogical needs. Finally, we present recommendations that help educators to use Slack in their educational practices.peerReviewe