Aging is the major risk factor for neurodegenerative disease, yet the mechanisms linking physiological aging to brain dysfunction remain unclear. We investigated the brains of telomere-shortened mice and observed lipofuscinosis, hypomyelination, microglial atrophy, and cognitive deficits. Single-nucleus RNA sequencing (snRNA-seq) revealed accelerated glial aging and elevated microglial senescence pathways. In a senescence model of human induced pluripotent stem cell (iPSC)-derived microglia, delta-like non-canonical Notch ligand 1 (DLK1) was identified as a novel senescence-associated ligand. Soluble DLK1 (sDLK1) was increased in the cerebrospinal fluid of telomere-shortened and naturally aged mice, and this increase was eliminated by microglial depletion. In vivo elevation of sDLK1 caused hypomyelination and blocked oligodendrocyte lineage progression, and these effects demonstrate the detrimental nature of excessive sDLK1. In human iPSC systems, sDLK1 impaired oligodendrocyte maturation and altered calcium signaling in excitatory neurons. These findings identify microglial senescence as a core consequence of telomere shortening and reveal sDLK1 as a microglia-derived senescence ligand that drives oligodendrocyte and neuronal dysfunction in aging.
Bangyan Liu, M. Mahoney, Yilin Feng et al.· Neuron· 0 citations
Truncating variants in the ALPK3 gene (encoding alpha protein kinase 3) cause severe cardiomyopathy for which no curative treatment exists1-3. Here we establish an adeno-associated virus (AAV)-mediated gene replacement therapy to deliver full-length human ALPK3. AAV-ALPK3 prevented disease in neonatal Alpk3-mutant mice and reversed established pathology in adults, with proteomic analysis demonstrating reversal of more than 95% of the molecular disease signature. Beyond ALPK3 deficiency, we explored broader therapeutic potential based on ALPK3's regulatory role in proteostasis, a pathway commonly disrupted across cardiomyopathies. ALPK3 expression is reduced in cardiomyocytes with TTN-truncating variants, the most prevalent cause of dilated cardiomyopathy, and the encoded titin protein has a protein quality control network in common with ALPK3. AAV-ALPK3 restored contractile function in human cardiac organoids with an ALPK3- or TTN-truncating variant. These findings provide proof of concept for ALPK3 gene therapy in patients with ALPK3 cardiomyopathy and reveal potential for indication expansion to cardiomyopathies associated with TTN-truncating variants, which are not amenable to gene replacement therapy due to size limitations.
James W. McNamara, Ellen B. Keen, Rebecca Sutton et al.· Nature Cardiovascular Resear...· 2 citations
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