Cholesterol availability is rate-limiting for myelination, and prior studies have established the importance of cholesterol synthesis by oligodendrocytes for normal CNS myelination. However, the contribution of cholesterol uptake through the endocytic pathway has not been fully explored. To address this question, we used mice with a conditional null allele of the Npc1 gene, which encodes a transmembrane protein critical for mobilizing cholesterol from the endolysosomal system. Loss of function mutations in the human NPC1 gene cause Niemann-Pick type C disease, a childhood-onset neurodegenerative disorder in which intracellular lipid accumulation, abnormally swollen axons, and neuron loss underlie the occurrence of early death. Both NPC patients and Npc1 null mice exhibit myelin defects indicative of dysmyelination, although the mechanisms underlying this defect are incompletely understood. Here we use temporal and cell-type-specific gene deletion in order to define effects on CNS myelination. Our results unexpectedly show that deletion of Npc1 in neurons alone leads to an arrest of oligodendrocyte maturation and to subsequent failure of myelin formation. This defect is associated with decreased activation of Fyn kinase, an integrator of axon-glial signals that normally promotes myelination. Furthermore, we show that deletion of Npc1 in oligodendrocytes results in delayed myelination at early postnatal days. Aged, oligodendocyte-specific null mutants also exhibit late stage loss of myelin proteins, followed by secondary Purkinje neuron degeneration. These data demonstrate that lipid uptake and intracellular transport by neurons and oligodendrocytes through an Npc1-dependent pathway is required for both the formation and maintenance of CNS myelin.
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http://dx.doi.org/10.1371/journal.pgen.1003462 | DOI Listing |
Front Pharmacol
December 2024
College of Pharmacy, Jinan University, Guangzhou, China.
Bone homeostasis encompasses two interrelated aspects: bone remodeling and cartilage metabolism. Disruption of bone homeostasis can lead to the development of metabolic bone diseases such as osteoporosis and osteoarthritis. The maintenance of bone homeostasis is a complex process that does not solely rely on the functions of the bone tissue itself.
View Article and Find Full Text PDFIn the central nervous system, apolipoprotein (APO) E-containing high-density lipoprotein (HDL)-like particles mediate the transport of glial-derived cholesterol to neurons, which is essential for neuronal membrane remodeling and maintenance of the myelin sheath. Despite this, the role of HDL-like cholesterol trafficking on Alzheimer's disease (AD) pathogenesis remains poorly understood. We aimed to examine cholesterol transport via HDL-like particles in cerebrospinal fluid (CSF) of AD patients compared to control individuals.
View Article and Find Full Text PDFBackground: The activation of brown adipose tissue (BAT) is associated with improved metabolic health in humans. We previously identified the mitochondrial protein 4-Nitrophenylphosphatase Domain and Non-Neuronal SNAP25-Like 1 (Nipsnap1) as a novel regulatory factor that integrates with lipid metabolism and is critical to sustain the long-term activation of BAT, but the precise mechanism and function of Nipsnap1 is unknown.
Objectives: Define how the regulatory factor Nipsnap1 integrates with lipid metabolism.
Tertiary lymphoid structures (TLS) are organized immune cell aggregates that arise in chronic inflammatory conditions. In cancer, TLS are associated with better prognosis and enhanced response to immunotherapy, making these structures attractive therapeutic targets. However, the mechanisms regulating TLS formation and maintenance in cancer are incompletely understood.
View Article and Find Full Text PDFInflamm Res
January 2025
Department of Pharmacy, University "G. d'Annunzio" of Chieti-Pescara, 66100, Chieti, Italy.
Objective: This study explores whether hyaluronic acid (HA) of different molecular weights and collagen, given their role in tendon extracellular matrix maintenance, have a synergistic effect on human tendon-derived cells, with the aim to improve the treatment of tendinopathy.
Material: Human monocytes (CRL-9855™) and primary Achilles tendon-derived cells.
Treatment: The collagen/HA ratio was based on the formulation of the commercial food supplement TendoGenIAL™.
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