The mammalian brain is complex, with multiple cell types performing a variety of diverse functions, but exactly how each cell type is affected with aging remains largely unknown. Here, we performed a single-cell transcriptomic analysis of young and old mouse brains. We provide comprehensive datasets of aging-related genes, pathways and ligand-receptor interactions in nearly all brain cell types. Our analysis identified gene signatures that vary in a coordinated manner across cell types and gene sets that are regulated in a cell-type specific manner, even at times in opposite directions. These data reveal that aging, rather than inducing a universal program, drives a distinct transcriptional course in each cell population, and highlight key molecular processes, including ribosome biogenesis, underlying brain aging. Overall, these largescale datasets provide an important resource for the neuroscience community (accessible online at https://portals.broadinstitute.org/single_cell/study/aging-mouse-brain) that will facilitate additional discoveries directed towards understanding and modifying the aging process.

Aging is the biggest risk factor for several neurodegenerative diseases. Parabiosis experiments have established that old mouse brains are improved by exposure to young mouse blood. Previously, our lab showed that delivery of Growth Differentiation Factor 11 (GDF11) to the bloodstream increases the number of neural stem cells and positively affects vasculature in the subventricular zone of old mice. Our new study demonstrates that GDF11 enhances hippocampal neurogenesis, improves vasculature and increases markers of neuronal activity and plasticity in the hippocampus and cortex of old mice. Our experiments also demonstrate that systemically delivered GDF11, rather than crossing the blood brain barrier, exerts at least some of its effects by acting on brain endothelial cells. Thus, by targeting the cerebral vasculature, GDF11 has a very different mechanism from that of previously studied circulating factors acting to improve central nervous system (CNS) function without entering the CNS.

Background:The tropomyosin receptor kinase B (TrkB) is a potential novel substrate of protein-tyrosine phosphatase 1B (PTP1B). Results: PTP1B associates with and plays a modulatory role in BDNF-induced TrkB signaling. Conclusion: PTP1B is a novel negative regulator of central BDNF/TrkB signaling. Significance: This is the first evidence that PTP1B deficiency enhances central TrkB signaling and alters BDNF-induced thermogenesis in vivo.

The mammalian brain is complex, with multiple cell types performing a variety of diverse functions, but exactly how the brain is affected with aging remains largely unknown. Here we performed a single-cell transcriptomic analysis of young and old mouse brains. We provide a comprehensive dataset of aging-related genes, pathways and ligand-receptor interactions in nearly all brain cell types. Our analysis identified gene signatures that vary in a coordinated manner across cell types and gene sets that are regulated in a cell type specific manner, even at times in opposite directions. Thus, our data reveals that aging, rather than inducing a universal program drives a distinct transcriptional course in each cell population. These data provide an important resource for the aging community and highlight key molecular processes, including ribosomal biogenesis, underlying aging. We believe that this large-scale dataset, which is publicly accessible online (aging-mouse-brain), will facilitate additional discoveries directed towards understanding and modifying the aging process.