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Biol Psychiatry. 2018 Mar 1;83(5):438-446. doi: 10.1016/j.biopsych.2017.06.007. Epub 2017 Jun 15.

DOPA Decarboxylase Modulates Tau Toxicity.

Author information

1
Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle Division, Washington; Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, Washington.
2
Mental Illness Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle Division, Washington; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington.
3
Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle Division, Washington.
4
Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle Division, Washington; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington.
5
Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle Division, Washington; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington; Department of Pathology, University of Washington, Seattle, Washington; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, Washington. Electronic address: kraemerb@u.washington.edu.

Abstract

BACKGROUND:

The microtubule-associated protein tau accumulates into toxic aggregates in multiple neurodegenerative diseases. We found previously that loss of D2-family dopamine receptors ameliorated tauopathy in multiple models including a Caenorhabditis elegans model of tauopathy.

METHODS:

To better understand how loss of D2-family dopamine receptors can ameliorate tau toxicity, we screened a collection of C. elegans mutations in dopamine-related genes (n = 45) for changes in tau transgene-induced behavioral defects. These included many genes responsible for dopamine synthesis, metabolism, and signaling downstream of the D2 receptors.

RESULTS:

We identified one dopamine synthesis gene, DOPA decarboxylase (DDC), as a suppressor of tau toxicity in tau transgenic worms. Loss of the C. elegans DDC gene, bas-1, ameliorated the behavioral deficits of tau transgenic worms, reduced phosphorylated and detergent-insoluble tau accumulation, and reduced tau-mediated neuron loss. Loss of function in other genes in the dopamine and serotonin synthesis pathways did not alter tau-induced toxicity; however, their function is required for the suppression of tau toxicity by bas-1. Additional loss of D2-family dopamine receptors did not synergize with bas-1 suppression of tauopathy phenotypes.

CONCLUSIONS:

Loss of the DDC bas-1 reduced tau-induced toxicity in a C. elegans model of tauopathy, while loss of no other dopamine or serotonin synthesis genes tested had this effect. Because loss of activity upstream of DDC could reduce suppression of tau by DDC, this suggests the possibility that loss of DDC suppresses tau via the combined accumulation of dopamine precursor levodopa and serotonin precursor 5-hydroxytryptophan.

KEYWORDS:

Aromatic amino acid decarboxylase; DOPA decarboxylase; Dopamine; Neurodegeneration; Serotonin; Tau

PMID:
28751068
PMCID:
PMC5732084
[Available on 2019-03-01]
DOI:
10.1016/j.biopsych.2017.06.007
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