Neuraminidase 1 (NEU1) cleaves terminal sialic acids from sialoglycoproteins in endolysosomes and at the plasma membrane. As such, NEU1 regulates immune cells, primarily those of the monocytic lineage. Here, we examine how Neu1 influences microglia by modulating the sialylation of full-length Trem2 (Trem2-FL), a multifunctional receptor that regulates microglial survival, phagocytosis, and cytokine production. When Neu1 is deficient/downregulated, Trem2-FL remains sialylated, accumulates intracellularly, and is excessively cleaved into a C-terminal fragment (Trem2-CTF) and an extracellular soluble domain (sTrem2), enhancing their signaling capacities. Sialylated Trem2-FL (Sia-Trem2-FL) does not hinder Trem2-FL-DAP12-Syk complex assembly but impairs signal transduction through Syk, ultimately abolishing Trem2-dependent phagocytosis. Concurrently, Trem2-CTF-DAP12 complexes dampen NF-κB signaling, while sTrem2 propagates Akt-dependent cell survival and NFAT1-mediated production of TNF-α and CCL3. Because NEU1 and Trem2 are implicated in neurodegenerative/neuroinflammatory diseases, including Alzheimer disease and sialidosis, modulating NEU1 activity represents a therapeutic approach to broadly regulate microglia-mediated neuroinflammation.
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http://dx.doi.org/10.1016/j.celrep.2024.115204 | DOI Listing |
Cell Rep
January 2025
Department of Genetics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Anatomy and Neurobiology, College of Graduate Health Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA. Electronic address:
Neuraminidase 1 (NEU1) cleaves terminal sialic acids from sialoglycoproteins in endolysosomes and at the plasma membrane. As such, NEU1 regulates immune cells, primarily those of the monocytic lineage. Here, we examine how Neu1 influences microglia by modulating the sialylation of full-length Trem2 (Trem2-FL), a multifunctional receptor that regulates microglial survival, phagocytosis, and cytokine production.
View Article and Find Full Text PDFJ Pediatr Endocrinol Metab
December 2024
Department of Neurology, Ankara Etlik City Hospital, Ankara, Türkiye.
Objectives: Sialidosis type 1 is a rare autosomal recessive lysosomal storage disorder caused by pathogenic variants in the gene, which encodes the sialic acid-degrading enzyme α-neuraminidase. Sialidosis type 1 is a milder form with a late-onset phenotype, characterized by progressive myoclonic epilepsy and ataxia with cherry-red spots. Sialidosis type 2 is an early-onset and more severe form presenting with dysmorphic features, hepatosplenomegaly and cognitive delay.
View Article and Find Full Text PDFThe international consensus Sepsis-3 in 2016 defined sepsis as life-threatening organ dysfunction caused by a disruption of the host response to infection. One of the main mechanisms leading to the death of patients with sepsis is an imbalance of the immune response to pathogens. Activation of immune cells, in particular neutrophils, plays a key role in the mechanisms of sepsis.
View Article and Find Full Text PDFInflammation
November 2024
Department of Periodontology, School and Hospital of Stomatology, China Medical University, No.117 Nanjing North Street, Heping District, Shenyang, 110002, Liaoning, China.
Periodontitis is a chronic inflammatory disease strongly influenced by host's immune response. Aberrant sialylation on cell surface plays a key role in inflammation and immunity. This study aims to identify sialylation-related genes associated with periodontitis and explore their impact on periodontal immune microenvironment.
View Article and Find Full Text PDFOrphanet J Rare Dis
November 2024
Department of Endocrinology, Beijing Children's Hospital, Capital Medical University, National Centre for Children's Health, Genetics, Metabolism, Beijing, 100045, China.
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