The C-terminus of the prototypical M2 muscarinic receptor localizes to the mitochondria and regulates cell respiration under stress conditions
Abstract
Muscarinic acetylcholine receptors are prototypical G protein-coupled receptors (GPCRs), members of a large family of 7 transmembrane receptors mediating a wide variety of extracellular signals. We show here, in cultured cells and in a murine model, that the carboxyl terminal fragment of the muscarinic M2 receptor, comprising the transmembrane regions 6 and 7 (M2tail), is expressed by virtue of an internal ribosome entry site localized in the third intracellular loop. Single-cell imaging and import in isolated yeast mitochondria reveals that M2tail, whose expression is up-regulated in cells undergoing integrated stress response, does not follow the normal route to the plasma membrane, but is almost exclusively sorted to the mitochondria inner membrane: here, it controls oxygen consumption, cell proliferation, and the formation of reactive oxygen species (ROS) by reducing oxidative phosphorylation. Crispr/Cas9 editing of the key methionine where cap-independent translation begins in human-induced pluripotent stem cells (hiPSCs), reveals the physiological role of this process in influencing cell proliferation and oxygen consumption at the endogenous level. The expression of the C-terminal domain of a GPCR, capable of regulating mitochondrial function, constitutes a hitherto unknown mechanism notably unrelated to its canonical signaling function as a GPCR at the plasma membrane. This work thus highlights a potential novel mechanism that cells may use for controlling their metabolism under variable environmental conditions, notably as a negative regulator of cell respiration.
Citation
Fasciani , I , Petragnano , F , Wang , Z , Edwards , R , Telugu , N , Pietrantoni , I , Zabel , U , Zauber , H , Grieben , M , Terzenidou , M E , Di Gregorio , J , Pellegrini , C , Santini , S , Taddei , A R , Pohl , B , Aringhieri , S , Carli , M , Aloisi , G , Marampon , F , Charlesworth , E , Roman , A , Diecke , S , Flati , V , Giorgi , F , Amicarelli , F , Tobin , A B , Scarselli , M , Tokatlidis , K , Rossi , M , Lohse , M J , Annibale , P & Maggio , R 2024 , ' The C-terminus of the prototypical M2 muscarinic receptor localizes to the mitochondria and regulates cell respiration under stress conditions ' , PLoS Biology , vol. 22 , no. 4 , e3002582 . https://doi.org/10.1371/journal.pbio.3002582
Publication
PLoS Biology
Status
Peer reviewed
ISSN
1544-9173Type
Journal article
Description
Funding: This study was further supported by European Union’s Horizon2020 Marie Skłodowska-Curie Actions (MSCA) Program under Grant Agreements 641833 and 860229 (ONCORNET and ONCORNET2.0 to MJL (https://oncornet.eu). PA would like to gratefully acknowledge support from the Leverhulme Trust (RL-2022-015) (www.leverhulme.ac.uk). Work in the KT lab was supported by grants UK Research and Innovation-Biotechnology and Biological Sciences Research Council (UKRI-BBSRC) BB/T003804/1, BB/R009031/1, BB/X511948/1 and UKRI-Medical Research Council (UKRI-MRC) MC_PC_19039 (https://www.ukri.org).Collections
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