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Updated: Jun 12, 2025

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Germline mutations in a G protein identify signaling cross-talk in T cells
Hyoungjun Ham1,2,3, Huie Jing1,2, Ian T Lamborn1,2,4
1Human Immunological Diseases Section, Laboratory of Clinical Immunology and Microbiology, Division of Intramural Research (DIR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
Abstract:
Humans with monogenic inborn errors responsible for extreme disease phenotypes can reveal essential physiological pathways. We investigated germline mutations in GNAI2, which encodes Gαi2, a key component in heterotrimeric G protein signal transduction usually thought to regulate adenylyl cyclase-mediated cyclic adenosine monophosphate (cAMP) production. Patients with activating Gαi2 mutations had clinical presentations that included impaired immunity. Mutant Gαi2 impaired cell migration and augmented responses to T cell receptor (TCR) stimulation. We found that mutant Gαi2 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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