AraC interacts with p75NTR transmembrane domain to induce cell death of mature neurons

Abstract

AbstractCytosine arabinoside (AraC) is one of the main therapeutic treatments for several types of cancer, including acute myeloid leukaemia. However, after a high-dose AraC chemotherapy regime, patients develop severe neurotoxicity and cell death in the central nervous system leading to cerebellar ataxia, dysarthria, nystagmus, somnolence and drowsiness. AraC induces apoptosis in dividing cells. However, the mechanism by which it leads to neurite degeneration and cell death in mature neurons remains unclear. We hypothesise that the upregulation of the death receptor p75NTRis responsible for AraC-mediated neurodegeneration and cell death in leukaemia patients undergoing AraC treatment. To determine the role of AraC-p75NTRsignalling in the cell death of mature neurons, we used mature cerebellar granule neurons’ primary cultures from p75NTRknockout andp75NTRCys259mice. Evaluation of neurite degeneration, cell death and p75NTRsignalling was done by immunohistochemistry and immunoblotting. To assess the interaction between AraC and p75NTR, we performed cellular thermal shift and AraTM assays as well as Homo-FRET anisotropy imaging. We show that AraC induces neurite degeneration and programmed cell death of mature cerebellar granule neurons in a p75NTR-dependent manner. Mechanistically, Proline 252 and Cysteine 256 residues facilitate AraC interaction with the transmembrane domain of p75NTRresulting in uncoupling of p75NTRfrom the NFκB survival pathway. This, in turn, exacerbates the activation of the cell death/JNK pathway by recruitment of TRAF6 to p75NTR. Our findings identify p75NTRas a novel molecular target to develop treatments for counteract AraC-mediated cell death of mature neurons.