👤 András Balla

Neuroblastoma (NB) represents a paradigmatic developmental malignancy in which lineage specification, oncogenic signalling, and epigenetic regulation converge to define tumour behaviour. Among the molecular axes shaping NB heterogeneity, neurotrophin receptors of the tropomyosin receptor kinase (Trk) family (TrkA, TrkB, and TrkC) and the p75NTR occupy a central position at the intersection between neuronal differentiation programs and malignant plasticity. While high TrkA and TrkC expression is associated with adrenergic identity, differentiation competence, and favourable clinical outcome, TrkB, frequently sustained by BDNF-driven autocrine loops, characterises mesenchymal-like, therapy-resistant states enriched in metabolic and inflammatory adaptations. Importantly, in NB, the dysregulation of neurotrophin signalling rarely arises from recurrent genetic alterations of neurotrophic tyrosine receptor kinase ( Show less

Phosphatidylinositol 4 kinase IIIα (PI4KIIIα/PI4KA) is an essential lipid kinase that plays a critical role in regulating plasma membrane identity. PI4KA is primarily recruited to the plasma membrane through the targeted recruitment by the proteins, EFR3A and EFR3B, which bind to the PI4KA accessory proteins TTC7 (TTC7A/B) and FAM126 (FAM126A/B). Here we characterised how both EFR3 isoforms interact with all possible TTC7-FAM126 combinations and developed a nanobody that specifically blocked EFR3-mediated PI4KA recruitment in TTC7B containing complexes. Most EFR3-TTC7-FAM126 combinations show similar binding affinities, with the exception of EFR3A-TTC7B-FAM126A, which binds with a ~10-fold higher affinity. Moreover, we showed that EFR3B phosphorylation markedly decreased binding to TTC7-FAM126. Using a yeast display approach, we isolated a TTC7B selective nanobody that blocked EFR3 binding. Cryo-electron microscopy and hydrogen deuterium exchange mass spectrometry showed an extended interface with both PI4KA and TTC7B that sterically blocks EFR3 binding. The nanobody caused decreased membrane recruitment both on lipid bilayers and in cells, with decreased PM production of PI4P. Collectively, these findings provide new insights into PI4KA regulation and provide a tool for manipulating PI4KA complexes, that may be valuable for therapeutic targeting. Show less

Phosphatidylinositol 4 kinase IIIα (PI4KIIIα/PI4KA) is an essential lipid kinase that plays a critical role in regulating plasma membrane (PM) identity. PI4KA is primarily recruited to the PM through the targeted recruitment by the proteins, EFR3A and EFR3B, which bind to the PI4KA accessory proteins, TTC7 (TTC7A/B) and FAM126 (FAM126A/B). Here, we characterized how both EFR3 isoforms interact with all possible TTC7-FAM126 combinations and developed a nanobody that specifically blocked EFR3-mediated PI4KA recruitment in TTC7B-containing complexes. Most EFR3-TTC7-FAM126 combinations show similar binding affinities, with the exception of EFR3A-TTC7B-FAM126A, which binds with a ∼10-fold higher affinity. Moreover, we showed that EFR3B phosphorylation markedly decreased binding to TTC7-FAM126. Using a yeast display approach, we isolated a TTC7B selective nanobody that blocked EFR3 binding. Cryo-EM and hydrogen deuterium exchange mass spectrometry showed an extended interface with both PI4KA and TTC7B that sterically blocks EFR3 binding. The nanobody caused decreased membrane recruitment both on lipid bilayers and in cells, with decreased PM production of phosphatidylinositol 4-phosphate. Collectively, these findings provide new insights into PI4KA regulation and provide a tool for manipulating PI4KA complexes, which may be valuable for therapeutic targeting. Show less

Lipoprotein(a) [Lp(a)] is a recognized risk factor for atherosclerotic cardiovascular disease. However, its potential association with the risk of recurrent atrial fibrillation (AF) after ablation remains unexplored. This study aimed to investigate whether Lp(a) serum levels are linked to the risk of recurrent AF following pulsed field ablation (PFA). A retrospective cohort analysis was conducted on patients who underwent PFA at the Cardiology Clinic of the Ferrara University Hospital from October 2023 to January 2025. Lp(a) percentile groups were established, with the first 50th percentile serving as the reference. Cox proportional hazards modeling was used to assess the relationship between Lp(a) percentile and recurrent AF after PFA. The study included 133 patients (mean age 59.6 years, 29.3% women). Over a median follow-up of 7.8 months after the blanking period (range: 6.4-9.3 months), 29 patients (21.8%) experienced confirmed recurrent AF. A continuous increase in the hazard of recurrent AF was observed with rising Lp(a) levels. Specifically, individuals in the 51st-70th, 71st-90th, and 91st-100th Lp(a) percentiles had adjusted hazard ratios of 1.13 [95% confidence interval (CI): 1.04-1.22, P < 0.001], 1.21 (95% CI: 1.11-1.31, P < 0.001), and 1.26 (95% CI: 1.13-1.39, P < 0.001), respectively. Elevated Lp(a) levels are associated with an increased risk of recurrent AF after PFA, suggesting that Lp(a)-lowering therapies may be beneficial for these patients. Show less

The lipid kinase phosphatidylinositol 4 kinase III α (PI4KIIIα/PI4KA) is a master regulator of the lipid composition and asymmetry of the plasma membrane. PI4KA exists primarily in a heterotrimeric complex with its regulatory proteins TTC7 and FAM126. Fundamental to PI4KA activity is its targeted recruitment to the plasma membrane by the lipidated proteins EFR3A and EFR3B. Here, we report a cryogenic electron microscopy structure of the C terminus of EFR3A bound to the PI4KA-TTC7B-FAM126A complex, with extensive validation using both hydrogen deuterium exchange mass spectrometry, and mutational analysis. The EFR3A C terminus undergoes a disorder-order transition upon binding to the PI4KA complex, with an unexpected direct interaction with both TTC7B and FAM126A. Complex disrupting mutations in TTC7B, FAM126A, and EFR3 decrease PI4KA recruitment to the plasma membrane. Multiple posttranslational modifications and disease linked mutations map to this site, providing insight into how PI4KA membrane recruitment can be regulated and disrupted in human disease. Show less

The lipid kinase phosphatidylinositol 4 kinase III alpha (PI4KIIIa/PI4KA) is a master regulator of the lipid composition and asymmetry of the plasma membrane. PI4KA exists primarily in a heterotrimeric complex with its regulatory proteins TTC7 and FAM126. Fundamental to PI4KA activity is its targeted recruitment to the plasma membrane by the lipidated proteins EFR3A and EFR3B. Here, we report a cryo-EM structure of the C-terminus of EFR3A bound to the PI4KA-TTC7B-FAM126A complex, with extensive validation using both hydrogen deuterium exchange mass spectrometry (HDX-MS), and mutational analysis. The EFR3A C-terminus undergoes a disorder-order transition upon binding to the PI4KA complex, with an unexpected direct interaction with both TTC7B and FAM126A. Complex disrupting mutations in TTC7B, FAM126A, and EFR3 decrease PI4KA recruitment to the plasma membrane. Multiple post-translational modifications and disease linked mutations map to this site, providing insight into how PI4KA membrane recruitment can be regulated and disrupted in human disease. Show less

Activation of the type I angiotensin receptor (AT1-R) in vascular smooth muscle cells (VSMCs) plays a crucial role in the regulation of blood pressure; however, it is also responsible for the development of pathological conditions such as vascular remodeling, hypertension and atherosclerosis. Stimulation of the VSMC by angiotensin II (AngII) promotes a broad variety of biological effects, including gene expression changes. In this paper, we have taken an integrated approach in which an analysis of AngII-induced gene expression changes has been combined with the use of small-molecule inhibitors and lentiviral-based gene silencing, to characterize the mechanism of signal transduction in response to AngII stimulation in primary rat VSMCs. We carried out Affymetrix GeneChip experiments to analyze the effects of AngII stimulation on gene expression; several genes, including Show less

The yeast Efr3p protein is a main regulator of the Stt4p phosphatidylinositol 4-kinase at contact sites between the endoplasmic reticulum and the plasma membrane. A mutation in its fly homologue Rbo, leads to diminished light responses in the eye attributed to progressively impaired PLC signaling. Here, we find that Efr3s plays a role in maintaining responsiveness to the type-I angiotensin II (AngII) receptors. siRNA-mediated depletion of EFR3A and EFR3B impaired the sustained phase of cytosolic Ca(2+) response to high concentration of AngII in HEK293 cells that express wild type but not truncated AGTR1 (AT1a receptor), missing the phosphorylation sites. Efr3 depletion had minimal effect on the recovery of plasma membrane phosphoinositides during stimulation, and AT1 receptors still underwent ligand-induced internalization. A higher level of basal receptor phosphorylation and a larger response was observed after stimulation. Moreover, Gq activation more rapidly desensitized after AngII stimulation in Efr3 downregulated cells. A similar but less pronounced effect of EFR3 depletion was observed on the desensitization of the cAMP response after stimulation with isoproterenol. These data suggest that mammalian Efr3s contribute to the control of the phosphorylation state and, hence, desensitization of AT1a receptors, and could affect responsiveness of G-protein-coupled receptors in higher eukaryotes. Show less