As one of the first propositions for GPCRs being present in mitochondrial membranes, a recent report from Robert Friedlander and colleagues  follows on from previous work characterising synaptic and extrasynaptic mitochondria in human cortex (post-mortem samples) and their role in neuroprotection. This work, if reproduced, opens up new vistas, and has many implications for neurodegenerative diseases. Taken together, Suofu et al. show that melatonin is synthesised in mitochondria, that MT1 receptors are present in mitochondrial membranes, and that MT1 receptor stimulation reduces cytochrome c and caspase secretion caused by calcium overload. The authors propose that this is a mechanism for the neuroprotective effects of melatonin in hypoxic-ischaemic brain injury in neonatal and in models of Huntington’s disease, where there is mitochondrial impairment.
Comments by Michael Spedding, Secretary General, IUPHAR, and CEO, Spedding Research Solutions SARL, France
(1) Suofu Y et al. (2017). Dual role of mitochondria in producing melatonin and driving GPCR signaling to block cytochrome c release. Proc Natl Acad Sci U S A., pii: 201705768. doi: 10.1073/pnas.1705768114. [Epub ahead of print] [PMID:28874589]