ATR regulates neuronal activity by modulating presynaptic firing

Murat Kirtay,Joanna Kirkpatrick,Christian Marx,Alessandro Ori,Christian Geis,Zhao-Qi Wang,Vahid Rahmati,Paulius Grigaravicius,Holger Haselmann,Josefine Sell,Katrin Buder,Mihai Ceanga,Zhong-Wei Zhou

doi:10.1038/s41467-021-24217-2

Abstract

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.

Highlights

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
A specific knockout of ATR in the central nervous system (CNS) of mice shows a crucial function of ATR in neuroprogenitor proliferation and DDR-mediated cell death[12,13].These biological functions of ATR derived from cellular and animal models highlight the importance of ATR-CHK1-mediated DDR in highly replicative cells
To investigate the function of ATR in a specific population of postmitotic neurons, we first generated a conditional knockout mouse model, wherein ATR was deleted in Purkinje cells (PCs) of the cerebellum (ATR-PCΔ) by crossing ATRflox mice[11] with L7/pcp2-Cre transgenic mice[27]

Summary

Introduction

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. ATR and its substrates CHK1 and TopBP1 are all essential to cell survival and constitutive deletion of these proteins causes lethality in animal models, as they are required to handle stalled replication fork damage in the S-phase checkpoint by modulating a serial of DDR cascade, including damage signaling and DNA repair[6,7,8,9,10]. Due to the essentiality of the Atr gene in vivo, the role of ATR in the pathogenesis of postnatal neurological and cognitive defects remains unknown The neurological symptoms, such as microcephaly, learning deficits and intellectual disabilities of ATR-SS patients and animal models, may well reflect abnormal neuron activities[15,16,17,20] and suggest a potential role for ATR in postmitotic neurons. We discover a physiological function of ATR in neuronal excitability and presynaptic function

Methods

Results

Conclusion