Year: 2026
Type: dissertation
Abstract: Centronuclear myopathies (CNM) are a group of currently incurable muscle disorders, characterized by abnormal localization of the nuclei. The symptoms vary from mild to very severe depending on the genetic subtype, one of which is caused by mutations in Bin1 gene (Bridging Integrator 1). The encoded BIN1 protein is a crescent shaped BAR protein, capable of sensing membrane curvature and binding to the plasma membrane of skeletal muscle cells, forming a complex tubular network. This tubular network consists of transverse tubules (T-tubules), which are necessary for muscle contraction to occur. Besides BIN1 being linked to CNM, it is of great medical relevance as it is also associated with more common syndromes and diseases, such as heart failure, cancer progression and late-onset Alzheimer’s disease. The challenge in treatment development, is that the underlying mechanisms are unknown. In this study, five mutations associated with CNM in BIN1 BAR domain, were investigated with in vitro nanotube reconstitution to assess the biophysical mechanisms by which muscle specific isoform 8 of BIN1 disrupts T-tubule network formation. The capacity to induce membrane curvature was studied with tubulation assays, and the impact on membrane properties with FCS Airyscan. The selected mutations, ΔK21, R24C, K35N, D151N and R154Q were successfully introduced to the engineered construct via site-directed mutagenesis, as well as expressed in E. coli strain and subsequently purified. This thesis demonstrates that CNM-linked BIN1 mutations have a variable effect on membrane remodeling, with some mutations causing more severe phenotypes than others. This thesis provides novel empirical evidence to the previously missing in vitro studies with mutations ΔK21 and R24C, as well as preliminary results on utilizing FCS Airyscan to assess the impact on membrane properties with BIN1 wild type.
Source: Aaltodoc (Aalto University)
Author: Dahl, Hanna
Institution: University of Helsinki
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7204619063