GIMAP7

GIMAP7 is a GTP-hydrolyzing member of the immunity-associated protein family that uses nucleotide-dependent self-association to regulate its own and partner GTPase activity, and acts as a membrane-associated modulator of autophagy and stress signaling (PMID:23454188, PMID:35551368). Structurally, it homodimerizes through its G domains and achieves dimerization-stimulated GTP hydrolysis via a trans-acting catalytic arginine finger, a mechanism it also extends in trans to stimulate hydrolysis by GIMAP2 (PMID:23454188). Within cells it associates with membranous organelles including lipid droplets, the ER, Golgi, and lysosomes (PMID:23454188, PMID:40728050). GIMAP7 functions in a tripartite GIMAP6–GABARAPL2–GIMAP7 complex required for normal autophagy and redox control in lymphocytes (PMID:35551368), and directly binds LC3B to convert incomplete autophagy flux into complete flux, coupling autophagy to apoptosis (PMID:40728050). In epithelial contexts GIMAP7 acts upstream of hedgehog-axis signaling, suppressing SHH/SMO/Gli1 in granulosa cells and Smo/AMPK signaling in lung adenocarcinoma cells, thereby restraining oxidative stress, EMT, and glycolysis (PMID:36581994, PMID:38151913).

1. 2013 High

   Established the biochemical identity of GIMAP7 as a GTPase and defined how its catalytic activity is controlled, answering how the protein hydrolyzes GTP and acts on a family member.

   Evidence Crystal structure of GTP-bound GIMAP7 with in vitro GTPase assays and catalytic-arginine mutagenesis, plus lipid droplet fractionation

   PMID:23454188

   Open questions at the time

   • Physiological trigger for homo- versus heterodimerization in cells not defined
   • Functional consequence of lipid-droplet localization untested
   • No cellular phenotype linked to the trans-arginine mechanism
2. 2022 Medium

   Placed GIMAP7 in a defined protein complex with GIMAP6 and GABARAPL2 linking its GTPase activity to autophagy and redox regulation in immune cells.

   Evidence Co-IP, GTPase assays, Gimap6-/- mice and GIMAP6-mutant patient cells

   PMID:35551368

   Open questions at the time

   • GIMAP7's individual contribution within the complex not isolated
   • Stoichiometry and assembly order unknown
   • Direct GIMAP7-GABARAPL2 contact not resolved
3. 2022 Medium

   Connected GIMAP7 to hedgehog signaling, showing it acts upstream of SHH/SMO/Gli1 to control oxidative stress, apoptosis, and proliferation in granulosa cells.

   Evidence siRNA knockdown in KGN cells and a PCOS rat model with pharmacological cyclopamine rescue

   PMID:36581994

   Open questions at the time

   • Molecular link between GIMAP7 GTPase activity and SHH pathway unresolved
   • Whether the effect is direct or indirect unknown
   • Single tissue context
4. 2023 Medium

   Extended GIMAP7's signaling role to tumor suppression in lung adenocarcinoma by demonstrating it inhibits Smo/AMPK-driven EMT and glycolysis.

   Evidence Gain- and loss-of-function in LUAD lines with metabolic assays, xenografts, and SAG/GSK621 pharmacological rescue

   PMID:38151913

   Open questions at the time

   • Direct binding partner mediating Smo/AMPK suppression unidentified
   • Relationship to GTPase mechanism unclear
   • Single lab
5. 2023 Low

   Associated GIMAP7 induction with downregulation of Rho/ROCK1 signaling in T cells, hinting at a role upstream of inflammatory GTPase pathways.

   Evidence RNA-seq of T cells from a nasal Foralumab clinical trial with pathway analysis

   PMID:36881624

   Open questions at the time

   • Transcriptomic correlation only; no direct manipulation of GIMAP7
   • Causality between GIMAP7 and Rho/ROCK1 not established
   • Mechanism unknown
6. 2025 Medium

   Defined a direct GIMAP7-LC3B interaction at membranous organelles that completes autophagy flux and triggers apoptosis, linking GIMAP7 to antiviral autophagy.

   Evidence Co-IP, subcellular imaging, autophagy flux readouts, and pharmacological GIMAP7 activation (narirutin, periplocin) in RSV infection models

   PMID:40728050

   Open questions at the time

   • LC3B-binding region of GIMAP7 not mapped
   • Whether GTPase activity is required for LC3B binding untested
   • Generality beyond RSV/lung cells unknown

• How GIMAP7's biochemical GTPase mechanism mechanistically connects to its diverse downstream roles in autophagy, hedgehog/AMPK signaling, and redox control remains unresolved.
• No unifying mechanism linking GTP hydrolysis to signaling outputs
• No structure of GIMAP7 in complex with LC3B or signaling partners
• Tissue-specific roles not reconciled