ATR regulates neuronal activity by modulating presynaptic firing

Ataxia Telangiectasia and Rad3-related (ATR) is a key regulator of replication stress response; yet, mutations within the ATR gene cause human ATR-Seckel Syndrome associated with microcephaly and intellectual disability. Here, the authors show neuron-specific ATR deletion increases intrinsic neuronal and epileptiform activity, revealing a function of ATR beyond its role in DNA damage response. Ataxia Telangiectasia and Rad3-related (ATR) protein, as a key DNA damage response (DDR) regulator, plays an essential function in response to replication stress and controls cell viability. Hypomorphic mutations of ATR cause the human ATR-Seckel syndrome, characterized by microcephaly and intellectual disability, which however suggests a yet unknown role for ATR in non-dividing cells. Here we show that ATR deletion in postmitotic neurons does not compromise brain development and formation; rather it enhances intrinsic neuronal activity resulting in aberrant firing and an increased epileptiform activity, which increases the susceptibility of ataxia and epilepsy in mice. ATR deleted neurons exhibit hyper-excitability, associated with changes in action potential conformation and presynaptic vesicle accumulation, independent of DDR signaling. Mechanistically, ATR interacts with synaptotagmin 2 (SYT2) and, without ATR, SYT2 is highly upregulated and aberrantly translocated to excitatory neurons in the hippocampus, thereby conferring a hyper-excitability. This study identifies a physiological function of ATR, beyond its DDR role, in regulating neuronal activity.

Automated summary

ATR, a key regulator of DNA damage response and replication stress, also plays a role in regulating neuronal activity beyond its known functions. Deletion of ATR in neurons leads to increased intrinsic activity, aberrant firing, and heightened epileptiform activity, potentially increasing susceptibility to ataxia and epilepsy.