S-Nitrosylation of Divalent Metal Transporter 1 Enhances Iron Uptake to Mediate Loss of Dopaminergic Neurons and Motoric Deficit Chao Liu, Cheng-Wu Zhang, Shun Qiang Lo, Seok Ting Ang, Katherine Chee Meng Chew, Dejie Yu, Bing Han Chai, Bobby Tan, Fai Tsang, Yee Kit Tai, Bryce Wei Quan Tan, Mui Cheng Liang, Hwee Tong Tan, Jia Ying Tang, Mitchell Kim Peng Lai, John Jia En Chua, Maxey Ching Ming Chung, Sanjay Khanna, Kah-Leong Lim, Tuck Wah Soong Journal of Neuroscience 26 September 2018, 38 (39) 8364-8377; DOI: 10.1523/JNEUROSCI.3262-17.2018
Elevated iron deposition has been reported in Parkinson's disease (PD). However, the route of iron uptake leading to high deposition in the substantia nigra is unresolved. Here, we show a mechanism in enhanced Fe2+ uptake via S-nitrosylation of divalent metal transporter 1 (DMT1). While DMT1 could be S-nitrosylated by exogenous nitric oxide donors, in human PD brains, endogenously S-nitrosylated DMT1 was detected in postmortem substantia nigra. Patch-clamp electrophysiological recordings and iron uptake assays confirmed increased Mn2+ or Fe2+ uptake through S-nitrosylated DMT1. We identified two major S-nitrosylation sites, C23 and C540, by mass spectrometry, and DMT1 C23A or C540A substitutions abolished nitric oxide (NO)-mediated DMT1 current increase. To evaluate in vivo significance, lipopolysaccharide (LPS) was stereotaxically injected into the substantia nigra of female and male mice to induce inflammation and production of NO. The intranigral LPS injection resulted in corresponding increase in Fe2+ deposition, JNK activation, dopaminergic neuronal loss and deficit in motoric activity, and these were rescued by the NO synthase inhibitor l-NAME or by the DMT1-selective blocker ebselen. Lentiviral knockdown of DMT1 abolished LPS-induced dopaminergic neuron loss.
This work was supported by the National Medical Research Council (NMRC), Ministry of Health, Singapore, with Grants NMRC/CBRG12nov078 and NMRC-TCR/013-NNI/2014 (to T.W.S.); and NMRC-EDG 10nov065 and NMRC-TCR/013-NNI/2014 (to K.-L.L.). We thank Tan Fong Yong for excellent technical assistance, and Dr. Chan Yiong Huak for the helpful comments on statistics.