Dataset Information

Decreased microglial Wnt/?-catenin signalling drives microglial pro-inflammatory activation in the developing brain.

ABSTRACT: Microglia of the developing brain have unique functional properties but how their activation states are regulated is poorly understood. Inflammatory activation of microglia in the still-developing brain of preterm-born infants is associated with permanent neurological sequelae in 9 million infants every year. Investigating the regulators of microglial activation in the developing brain across models of neuroinflammation-mediated injury (mouse, zebrafish) and primary human and mouse microglia we found using analysis of genes and proteins that a reduction in Wnt/?-catenin signalling is necessary and sufficient to drive a microglial phenotype causing hypomyelination. We validated in a cohort of preterm-born infants that genomic variation in the Wnt pathway is associated with the levels of connectivity found in their brains. Using a Wnt agonist delivered by a blood-brain barrier penetrant microglia-specific targeting nanocarrier we prevented in our animal model the pro-inflammatory microglial activation, white matter injury and behavioural deficits. Collectively, these data validate that the Wnt pathway regulates microglial activation, is critical in the evolution of an important form of human brain injury and is a viable therapeutic target.

SUBMITTER: Van Steenwinckel J

PROVIDER: S-EPMC6906599 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Decreased microglial Wnt/β-catenin signalling drives microglial pro-inflammatory activation in the developing brain.

Van Steenwinckel Juliette J Schang Anne-Laure AL Krishnan Michelle L ML Degos Vincent V Delahaye-Duriez Andrée A Bokobza Cindy C Csaba Zsolt Z Verdonk Franck F Montané Amélie A Sigaut Stéphanie S Hennebert Olivier O Lebon Sophie S Schwendimann Leslie L Le Charpentier Tifenn T Hassan-Abdi Rahma R Ball Gareth G Aljabar Paul P Saxena Alka A Holloway Rebecca K RK Birchmeier Walter W Baud Olivier O Rowitch David D Miron Veronique V Chretien Fabrice F Leconte Claire C Besson Valérie C VC Petretto Enrico G EG Edwards A David AD Hagberg Henrik H Soussi-Yanicostas Nadia N Fleiss Bobbi B Gressens Pierre P

Brain : a journal of neurology 20191201 12

Microglia of the developing brain have unique functional properties but how their activation states are regulated is poorly understood. Inflammatory activation of microglia in the still-developing brain of preterm-born infants is associated with permanent neurological sequelae in 9 million infants every year. Investigating the regulators of microglial activation in the developing brain across models of neuroinflammation-mediated injury (mouse, zebrafish) and primary human and mouse microglia we ...[more]

PMID: 31665242

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Project description:Triggering Receptor Expressed on Myeloid cells 2 (TREM2), which is expressed on myeloid cells including microglia in the CNS, has recently been identified as a risk factor for Alzheimer's disease (AD). TREM2 transmits intracellular signals through its transmembrane binding partner DNAX-activating protein 12 (DAP12). Homozygous mutations inactivating TREM2 or DAP12 lead to Nasu-Hakola disease; however, how AD risk-conferring variants increase AD risk is not clear. To elucidate the signaling pathways underlying reduced TREM2 expression or loss of function in microglia, we respectively knocked down and knocked out the expression of TREM2 in in vitro and in vivo models. We found that TREM2 deficiency reduced the viability and proliferation of primary microglia, reduced microgliosis in Trem2-/- mouse brains, induced cell cycle arrest at the G1/S checkpoint, and decreased the stability of β-catenin, a key component of the canonical Wnt signaling pathway responsible for maintaining many biological processes, including cell survival. TREM2 stabilized β-catenin by inhibiting its degradation via the Akt/GSK3β signaling pathway. More importantly, treatment with Wnt3a, LiCl, or TDZD-8, which activates the β-catenin-mediated Wnt signaling pathway, rescued microglia survival and microgliosis in Trem2-/- microglia and/or in Trem2-/- mouse brain. Together, our studies demonstrate a critical role of TREM2-mediated Wnt/β-catenin pathway in microglial viability and suggest that modulating this pathway therapeutically may help to combat the impaired microglial survival and microgliosis associated with AD.SIGNIFICANCE STATEMENT Mutations in the TREM2 (Triggering Receptor Expressed on Myeloid cells 2) gene are associated with increased risk for Alzheimer's disease (AD) with effective sizes comparable to that of the apolipoprotein E (APOE) ε4 allele, making it imperative to understand the molecular pathway(s) underlying TREM2 function in microglia. Our findings shed new light on the relationship between TREM2/DNAX-activating protein 12 (DAP12) signaling and Wnt/β-catenin signaling and provide clues as to how reduced TREM2 function might impair microglial survival in AD pathogenesis. We demonstrate that TREM2 promotes microglial survival by activating the Wnt/β-catenin signaling pathway and that it is possible to restore Wnt/β-catenin signaling when TREM2 activity is disrupted or reduced. Therefore, we demonstrate the potential for manipulating the TREM2/β-catenin signaling pathway for the treatment of AD.

Dataset Information

Decreased microglial Wnt/?-catenin signalling drives microglial pro-inflammatory activation in the developing brain.

Publications

Decreased microglial Wnt/β-catenin signalling drives microglial pro-inflammatory activation in the developing brain.

Similar Datasets

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