Astrocytic chordin-like 1 (Chrdl1) is re-engaged early after ischemic stroke to regulate region-dependent GluA2 levels and neuronal vulnerability

Abstract

Neuronal vulnerability to ischemic stroke varies markedly across brain regions, yet the mechanisms underlying this selective susceptibility remain poorly understood. Here, we show that the developmental astrocytic protein Chordin-like 1 (Chrdl1) is repurposed after ischemic injury to regulate neuronal vulnerability. Chrdl1 expression stabilizes GluA2-containing AMPA receptors, limits delayed apoptotic neuronal death, and preserves hippocampal function early after focal ischemic stroke, whereas sustained Chrdl1 expression does not improve long-term recovery. These findings identify an unexpected neuroprotective role for Chrdl1 during acute ischemia that contrasts with its previously described function as a limiter of synaptic plasticity during recovery. Our work reveals that developmental astrocyte-derived signaling can be redeployed after brain injury, with distinct functions depending on the stage of stroke and region-dependent endogenous expression that together determine whether a conserved neuroprotective mechanism is engaged after ischemic stroke.