Publication Date:
2017-09-05
Description:
G protein-coupled receptors (GPCRs) are classically characterized as cell-surface receptors transmitting extracellular signals into cells. Here we show that central components of a GPCR signaling system comprised of the melatonin type 1 receptor (MT1), its associated G protein, and β-arrestins are on and within neuronal mitochondria. We discovered that the ligand melatonin is exclusively synthesized in the mitochondrial matrix and released by the organelle activating the mitochondrial MT1signal-transduction pathway inhibiting stress-mediated cytochromecrelease and caspase activation. These findings coupled with our observation that mitochondrial MT1overexpression reduces ischemic brain injury in mice delineate a mitochondrial GPCR mechanism contributing to the neuroprotective action of melatonin. We propose a new term, “automitocrine,” analogous to “autocrine” when a similar phenomenon occurs at the cellular level, to describe this unexpected intracellular organelle ligand–receptor pathway that opens a new research avenue investigating mitochondrial GPCR biology.
Print ISSN:
0027-8424
Electronic ISSN:
1091-6490
Topics:
Biology
,
Medicine
,
Natural Sciences in General
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