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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Mol. Neurosci. | doi: 10.3389/fnmol.2019.00252

NCS-1 deficiency affects mRNA-levels of genes involved in regulation of ATP-Synthesis and mitochondrial stress in highly vulnerable Substantia nigra dopaminergic neurons

 Birgit Liss1, 2*, Carsten Simons1, Julia Benkert1, Nora Deuter1, Olaf Pongs3,  Toni Schneider4 and  Johanna Duda1
  • 1Institute of Applied Physiology, Faculty of Medicine, University of Ulm, Germany
  • 2New College, University of Oxford, United Kingdom
  • 3Institute of Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Germany
  • 4Institute of Neurophysiology, Faculty of Medicine, University of Cologne, Germany

Neuronal Ca2+ sensor proteins (NCS) transduce changes in Ca2+ homeostasis into altered signaling and neuronal function. NCS-1 activity has emerged as important for neuronal viability and pathophysiology. The progressive degeneration of DA neurons, particularly within the Substantia nigra (SN), is the hallmark of Parkinson’s disease (PD), causing its motor-symptoms. The activity-related Ca2+ homeostasis of SN DA neurons, mitochondrial dysfunction, and metabolic stress promote neurodegeneration and PD. In contrast, NCS-1 in general has neuroprotective effects. The underlying mechanisms are unclear.
We analyzed transcriptional changes in SN DA neurons upon NCS-1 loss by combining laser-microdissection and RT-qPCR-approaches to compare expression-levels of a panel of PD and/or Ca2+-stress related genes from wildtype and NCS-1 KO mice. In NCS-1 KO, we detected significantly lower mRNA-levels of mitochondrially coded ND1, a subunit of the respiratory chain, and of the neuron-specific enolase ENO2, a glycolytic enzyme. We also detected lower levels of the mitochondrial uncoupling proteins UCP4 and UCP5, the PARK7 gene-product DJ-1, and the Ca2+ channel Cav2.3 in SN DA neurons from NCS-1 KO. Transcripts of other analyzed UCPs, mitochondrial Ca2+ transporters, PARK-genes, and ion channels were not altered. As Cav channels are linked to regulation of gene-expression, metabolic stress and degeneration of SN DA neurons in PD, we analyzed Cav2.3 KO mice, to address if the transcriptional changes in NCS-1 KO were also present in Cav.2.3 KO, and thus probably correlated with lower Cav2.3-transcripts. However, in SN DA neurons from Cav2.3 KO mice, ND1 mRNA- as well as genomic DNA-levels were elevated, while ENO2, UCP4, UCP5 and DJ-1 transcript-levels were not altered.
In conclusion, our data indicate a possible novel function of NCS-1 in regulating gene-transcription or stabilization of mRNAs in SN DA neurons. Although we do not provide functional data, our findings at the transcript level could point to impaired ATP-production (lower ND1 and ENO2) and elevated metabolic stress (lower UCP4, UCP5, and DJ-1 levels) in SN DA neurons from NCS-1 KO. We speculate that NCS-1 is involved in stimulating ATP-synthesis, while at the same time controlling mitochondrial metabolic stress, and in this way could protect SN DA neurons from degeneration.

Keywords: Parkinson ' s disease, ND1, ENO2, mitochondrial uncoupling proteins, Voltage-gated calcium channel (VGCC), Cav2.3, KChip3/DREAM/Calsenilin, DJ-1/Park7

Received: 20 Dec 2018; Accepted: 27 Sep 2019.

Copyright: © 2019 Liss, Simons, Benkert, Deuter, Pongs, Schneider and Duda. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Birgit Liss, Institute of Applied Physiology, Faculty of Medicine, University of Ulm, Ulm, 89081, Baden-Wurttemberg, Germany, birgit.liss@uni-ulm.de