ResearchIn-Press PreviewMetabolismNeuroscience
Open Access | 10.1172/jci.insight.181339
1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
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1School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
2Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States of America
Find articles by Li, X. in: JCI | PubMed | Google Scholar
Published June 18, 2024 - More info
Loss-of-function mutations of the gene encoding the trafficking protein particle complex subunit 9 (trappc9) cause autosomal recessive intellectual disability and obesity by unknown mechanisms. Genome-wide analysis links trappc9 to non-alcoholic fatty liver disease (NAFLD). Trappc9-deficient mice have been shown to appear overweight shortly after weaning. Here, we analyzed serum biochemistry and histology of adipose and liver tissues to determine the incidence of obesity and NAFLD in trappc9-deficient mice and combined transcriptomic and proteomic analyses, pharmacological studies, and biochemical and histological examinations of postmortem mouse brains to unveil mechanisms involved. We found that trappc9-deficient mice presented with systemic glucose homeostatic disturbance, obesity and NAFLD, which were relieved upon chronic treatment combining dopamine receptor D2 (DRD2) agonist quinpirole and DRD1 antagonist SCH23390. Blood glucose homeostasis in trappc9-deficient mice was restored upon administrating quinpirole alone. RNA-sequencing analysis of DRD2-containing neurons and proteomic study of brain synaptosomes revealed signs of impaired neurotransmitter secretion in trappc9-deficient mice. Biochemical and histological studies of mouse brains showed that trappc9-deficient mice synthesized dopamine normally, but their dopamine-secreting neurons had a lower abundance of structures for releasing dopamine in the striatum. Our study suggests that trappc9 loss-of-function causes obesity and NAFLD by constraining dopamine synapse formation.