ISR activation mediates the behavioral and neurophysiological abnormalities in Down syndrome

Down syndrome (DS) is the most common genetic cause of intellectual disability and a major biomedical concern. Despite a general consensus that protein homeostasis is essential for normal brain function, little is known about its role in DS. Here, we show that the integrated stress response (ISR)—a conserved signaling network that maintains proteostasis by controlling protein synthesis—is activated in the brains of DS mice and individuals with DS, leading to reduced translation. Genetic and pharmacological suppression of the ISR, either by inhibiting the ISR-initiating double-stranded RNA-activated protein kinase (PKR) or boosting the function of the eIF2•eIF2B complex, which becomes limiting upon ISR activation, de-repressed translation, reversed enhanced inhibitory synaptic transmission, and rescued the deficits in synaptic plasticity and memory in DS mice. Our findings unveil a crucial role for the ISR in DS pathophysiology and suggest tuning of the ISR as a promising therapeutic intervention for DS. Overall design: Ribosome associated mRNA-seq of Ts65Dn, Ts65Dn-Pkr-/- and WT Mus Musculus