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Intracellular trafficking of receptor proteins is essential for neurons to detect various extracellular factors during the formation and refinement of neural circuits. However, the precise mechanisms underlying the trafficking of neurotrophin receptors to synapses remain elusive. Here, we demonstrate that a brain-enriched sorting nexin, ARHGAP33, is a new type of regulator for the intracellular trafficking of TrkB, a high-affinity receptor for brain-derived neurotrophic factor. ARHGAP33 knockout (KO) mice exhibit reduced expression of synaptic TrkB, impaired spine development and neuropsychiatric disorder-related behavioural abnormalities. These deficits are rescued by specific pharmacological enhancement of TrkB signalling in ARHGAP33 KO mice. Mechanistically, ARHGAP33 interacts with SORT1 to cooperatively regulate TrkB trafficking. Human ARHGAP33 is associated with brain phenotypes and reduced SORT1 expression is found in patients with schizophrenia. We propose that ARHGAP33/SORT1-mediated TrkB trafficking is essential for synapse development and that the dysfunction of this mechanism may be a new molecular pathology of neuropsychiatric disorders.
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http://dx.doi.org/10.1038/ncomms10594 | DOI Listing |
J Control Release
September 2025
Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, Switzerland. Electronic address:
Iron-carbohydrate complexes (ICCs) are widely used nanomedicines to treat iron deficiency anemia, yet their intracellular fate and the mechanisms of action underlying their differences in treatment outcomes remain poorly understood. Here, we thus performed a comprehensive dynamic characterization of two structurally distinct ICCs - iron sucrose (IS) and ferric carboxymaltose (FCM) - in primary human macrophages, key cells to the iron metabolism. By employing innovative correlative microscopy techniques, elemental analysis, and in vitro pharmacokinetic profiling, we demonstrate that the uptake, intracellular trafficking, and biodegradation of ICCs depend on their physicochemical properties.
View Article and Find Full Text PDFMol Cells
September 2025
Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea. Electronic address:
Proper subcellular localization of Toll-like receptors (TLRs) is essential for initiating appropriate innate immune responses against pathogens while avoiding self-reactivity. UNC93B1 is known to mediate the intracellular trafficking of nucleotide-sensing TLRs such as TLR9 which undergoes rapid internalization into endolysosomes upon reaching the cell surface. We previously demonstrated that UNC93B1 also facilitates the plasma membrane localization of TLR5, a sensor for bacterial flagellin.
View Article and Find Full Text PDFCurr Biol
September 2025
Molecular Cell Biology Group, Helmholtz Centre for Infection Research (HZI), Inhoffenstraße 7, 38124 Braunschweig, Germany; Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Braunschweig, Germany; Braunschweig Integrated Centre
Dynamic actin filament remodeling is crucial for a plethora of fundamental cell biological processes, ranging from cell division and migration to cell communication, intracellular trafficking, or tissue development. Cytochalasin B (CB) and D (CD) are fungal secondary metabolites frequently used for interference with such processes. Although they are generally assumed to block actin filament polymerization at their rapidly growing barbed ends and compete with regulators at these sites, precise molecular understanding of their effects in dynamic actin structures requires further study.
View Article and Find Full Text PDFBrain Dev
September 2025
Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Japan.
Hypomyelinating leukodystrophies (HLDs) are a group of inherited disorders characterized by impaired myelin formation in the central nervous system. Among them, Pelizaeus-Merzbacher disease (PMD) is a well-defined X-linked leukodystrophy caused by mutations in the PLP1 gene, including duplications, missense variants, and null mutations. Recent studies have revealed that different types of PLP1 mutations lead to distinct pathomechanisms: while missense mutations induce endoplasmic reticulum stress and activate the unfolded protein response (UPR), PLP1 duplications cause aberrant intracellular trafficking and cholesterol accumulation without UPR activation.
View Article and Find Full Text PDFAutophagy Rep
September 2025
Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Autophagy is an evolutionarily conserved cellular process that is prominent during bacterial infections. In this review article, we discuss how direct pathogen clearance via xenophagy and regulation of inflammatory products represent dual functions of autophagy that coordinate an effective antimicrobial response. We detail the molecular mechanisms of xenophagy, including signals that indicate the presence of an intracellular pathogen and autophagy receptor-mediated cargo targeting, while highlighting pathogen counterstrategies, such as bacterial effector proteins that inhibit autophagy initiation or exploit autophagic membranes for replication.
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