Stogsdill, J. A. | Search bioRxiv

bioRxiv2026

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

neuroscience↗

bioRxiv2024

Pyramidal neurons proportionately alter the identity and survival of specific cortical interneuron subtypes

The mammalian cerebral cortex comprises a complex neuronal network that maintains a precise balance between excitatory pyramidal neurons and inhibitory interneurons. Accumulating evidence indicates that specific interneuron subtypes form stereotyped microcircuits with distinct pyramidal neuron classes. Here we show that pyramidal neurons play an active role in this process by promoting the survival and terminal differentiation of their associated interneuron subtypes. In wild-type cortex, interneuron subtype abundance mirrors the prevalence of their pyramidal neuron partners. In Fezf2 mutants, which lack layer 5b pyramidal neurons and are expanded in layer 6 intratelencephalic neurons, corresponding subtype-specific shifts occur through two distinct mechanisms: somatostatin interneurons adjust their programmed cell death, whereas parvalbumin interneurons switch their subtype identity. Silencing neuronal activity or blocking vesicular release in L5b pyramidal neurons revealed that their communication with interneurons does not require voltage-gated synaptic activity and engages both tetanus toxin-sensitive and -insensitive pathways. Moreover, a targeted bioinformatic screen for ligand-receptor pairs displaying subtype-specific expression and reduced expression of pyramidal neuron-derived ligand in Fezf2 mutants identified candidate secreted factors and adhesion molecules. These findings reveal distinct, pyramidal neuron-driven mechanisms for sculpting interneuron diversity and integrating them into local cortical circuits.

neuroscience↗