N-terminal functional domain of Gasdermin A3 regulates mitochondrial homeostasis via mitochondrial targeting

Abstract

BackgroundThe epidermis forms a critical barrier that is maintained by orchestrated programs of proliferation, differentiation, and cell death. Gene mutations that disturb this turnover process may cause skin diseases. Human GASDERMIN A (GSDMA) is frequently silenced in gastric cancer cell lines and its overexpression has been reported to induce apoptosis. GSDMA has also been linked with airway hyperresponsiveness in genetic association studies. The function of GSDMA in the skin was deduced by dominant mutations in mouse gasdermin A3 (Gsdma3), which caused skin inflammation and hair loss. However, the mechanism for the autosomal dominance of Gsdma3 mutations and the mode of Gsdma3’s action remain unanswered.ResultsWe demonstrated a novel function of Gsdma3 in modulating mitochondrial oxidative stress. We showed that Gsdma3 is regulated by intramolecular fold-back inhibition, which is disrupted by dominant mutations in the C-terminal domain. The unmasked N-terminal domain of Gsdma3 associates with Hsp90 and is delivered to mitochondrial via mitochondrial importer receptor Tom70, where it interacts with the mitochondrial chaperone Trap1 and causes increased production of mitochondrial reactive oxygen species (ROS), dissipation of mitochondrial membrane potential, and mitochondrial permeability transition (MPT). Overexpression of the C-terminal domain of Gsdma3 as well as pharmacological interventions of mitochondrial translocation, ROS production, and MPT pore opening alleviate the cell death induced by Gsdma3 mutants.ConclusionsOur results indicate that the genetic mutations in the C-terminal domain of Gsdma3 are gain-of-function mutations which unmask the N-terminal functional domain of Gsdma3. Gsdma3 regulates mitochondrial oxidative stress through mitochondrial targeting. Since mitochondrial ROS has been shown to promote epidermal differentiation, we hypothesize that Gsdma3 regulates context-dependent response of keratinocytes to differentiation and cell death signals by impinging on mitochondria.Electronic supplementary materialThe online version of this article (doi:10.1186/s12929-015-0152-0) contains supplementary material, which is available to authorized users.

Gene polymorphism linked to increased asthma and IBD risk alters gasdermin-B structure, a sulfatide and phosphoinositide binding protein

“…Subsequent reports confirmed the binding of GSDMD_N to PtdIns(4)P, PtdIns(3,4)P 2 , phosphatidic acid, and cardiolipin, and weakly to phosphatidylserine (32). Because cardiolipin is a component of the inner leaflet of mitochondrial membrane, the binding data substantiated previous results that Gsdma3 is transported into the mitochondria to disrupt mitochondrial membranes (26,27) although mitochondrial localization was not reported for GSDMD. For GSDMD, phospholipid binding enables higher order oligomerization of the GSDMD N-terminal domain in the lipid bilayer and formation of ring structure-like pores to disrupt membrane structure.…”

“…Recent reports identified the N-terminal domain of mouse Gsdma3, expressed in HEK293 and HaCatT cells, as well as Gsdma3 mutants that cause skin and hair defects in mice, to promote cell death (26,27). Similarly, the N-terminal domains of human GSDMA, GSDMC, and GSDMD caused autophagy whereas the cells remain viable in the presence of the respective C-terminal domains (27).…”

“…Similarly, the N-terminal domains of human GSDMA, GSDMC, and GSDMD caused autophagy whereas the cells remain viable in the presence of the respective C-terminal domains (27). For Gsdam3, the autophagy is initiated when the N-terminal domain binds to heat shock protein 90 (HSP90), and the complex is delivered to the mitochondria by the HSP90/HSP70/ Hop complex via the Tom70 importer (26). Subsequent association of the Gsdma3 N-terminal domain with the mitochondrial chaperone TRAP1 promotes the production of reactive oxygen species (ROS), causing mitochondrial stress and loss of membrane integrity.…”

Active Caspase-1 Induces Plasma Membrane Pores That Precede Pyroptotic Lysis and Are Blocked by Lanthanides

“…This difference between the effects of Gsdmd knockout and lanthanide blockade of the pyroptotic pore on the rate of pyroptotic lysis indicates multiple roles for Gsdmd in integrating pyroptotic signaling downstream of inflammasome activation. Another member of the Gsdm family Gsdma3 has been shown to facilitate mitochondria-dependent cell death (76). Gain of function mutations in the C-terminus of Gsdma3 relieve its autoinhibitory interaction with the N-terminus (76).…”

“…Another member of the Gsdm family Gsdma3 has been shown to facilitate mitochondria-dependent cell death (76). Gain of function mutations in the C-terminus of Gsdma3 relieve its autoinhibitory interaction with the N-terminus (76). The N-terminal exposed Gsdma3 is recruited to mitochondria to mediate mitochondrial permeability transition (MPT) and ROS production which disrupts mitochondrial ATP production and drives cell death (76).…”