Comprehensive single cell profiling of ageing glial cells reveals impaired Wnt signalling and Jun transcription factors regulating cortical astrocytes

Understanding age-related cellular dysfunction in the brain is essential for developing strategies to promote healthy ageing. Towards this aim, we took advantage of a previously established mild dissociation method to profile cells in the cerebral cortex grey matter of adult and aged mice. This revealed glial cells with largely up-regulated and other glia and neurons with largely down-regulated gene expression upon ageing. Astrocytes were involved in increased interactions with microglia and decreased interaction with neurons, high-lighting potent age-induced changes in their regulatory roles. Single cell RNA-seq and single nuclei multiome analysis of astrocytes uncovered down-regulation of Wnt-signalling with increased expression of its inhibitors and reduced RNA and protein levels of its effectors JunB/D, acting downstream of Wnt signalling in ageing. This was confirmed by RNA-scope and immunostainings, as well as in human data. Notably, injection of JunD-expressing viral vectors in astrocytes increased their proliferation and HMGB1 levels in the aged brain, indicative of a more youthful astrocyte state. Main pointsO_LITranscriptomic analysis uncovers cell type-specific impact of ageing in the cortical grey matter, including altered intercellular communication networks. C_LIO_LIMultiomic profiling identifies dysregulated Wnt signalling in ageing cortical astrocytes. C_LIO_LIAgeing astrocytes exhibit upregulation of the Wnt signalling regulators Maml2 and Daam2, accompanied by downregulation of the AP-1 transcriptional complex component JunD. C_LIO_LIOverexpression of JunD increases proliferation after mild injury in aged astrocytes. C_LI