Germline mutations in a G protein identify signaling cross-talk in T cells.

Ham, Hyoungjun; Jing, Huie; Lamborn, Ian T; Kober, Megan M; Koval, Alexey; Berchiche, Yamina A; Anderson, D Eric; Druey, Kirk M et al. · Science · 2024

basic_science · Level V

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Abstract

Humans with monogenic inborn errors responsible for extreme disease phenotypes can reveal essential physiological pathways. We investigated germline mutations in <i>GNAI2</i>, which encodes G<sub>αi2</sub>, a key component in heterotrimeric G protein signal transduction usually thought to regulate adenylyl cyclase-mediated cyclic adenosine monophosphate (cAMP) production. Patients with activating G<sub>αi2</sub> mutations had clinical presentations that included impaired immunity. Mutant G<sub>αi2</sub> impaired cell migration and augmented responses to T cell receptor (TCR) stimulation. We found that mutant G<sub>αi2</sub> influenced TCR signaling by sequestering the guanosine triphosphatase (GTPase)-activating protein RASA2, thereby promoting RAS activation and increasing downstream extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)-AKT S6 signaling to drive cellular growth and proliferation.

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