Micranthin B alleviates metabolic dysfunction-associated steatohepatitis by targeting G3BP1 to improve stress granule-mediated endoplasmic reticulum stress

Abstract

Ras-GTPase activating protein SH3 domain-binding protein 1 (G3BP1), a core component of stress granules (SGs), is highly expressed in several liver diseases. SG assembly has also been observed in metabolic disorders, suggesting that this process may be a promising therapeutic target. Using a high-content drug screening approach based on G3BP1 expression, we identified Micranthin B (MB), a diterpenoid from Isodon lophanthoides (Buch.-Ham. ex D. Don) Hara, as a compound that alleviates metabolic dysfunction-associated steatohepatitis (MASH) by targeting G3BP1 and inhibiting SG formation. MB administration significantly alleviated MASH progression in both high-fat, high-cholesterol (HFHC) diet-induced mouse model and palmitic acid (PA)-stimulated hepatocytes. Mechanistically, MB inhibited histone deacetylase 6 (HDAC6)-mediated deacetylation of G3BP1, thereby suppressing SG formation. This prevented SG-mediated recruitment of the N-glycosylation-related proteins SEC61 translocon subunit beta (SEC61B) and calnexin (CANX), reduced the accumulation of misfolded or unfolded proteins, and alleviated endoplasmic reticulum (ER) stress. These findings suggest that MB has therapeutic potential in the treatment of MASH.

Keywords

MASH / Micranthin B / G3BP1 / Stress granule / Endoplasmic reticulum homeostasis

Declaration of Competing Interests

These authors have no conflict of interest to declare.

References

[1] Ha S, Wong VWS, Zhang X, et al. Interplay between gut microbiome, host genetic and epigenetic modifications in MASLD and MASLD—related hepatocellular carcinoma. Gut. 2025; 74(1):141-152. https://doi.org/10.1136/gutjnl—2024—332398.

[2] Do A, Zahrawi F, Mehal WZ. Therapeutic landscape of metabolic dysfunction—associated steatohepatitis (MASH). Nat Rev Drug Discov. 2025; 24(3):171-189. https://doi.org/10.1038/s41573—024—01084—2.

[3] Younossi ZM, Stepanova M, Ong J, et al. Nonalcoholic steatohepatitis is the most rapidly increasing indication for liver transplantation in the United States. Clin Gastroenterol Hepatol. 2021; 19(3):580-589. https://doi.org/10.1016/j.cgh.2020.05.064.

[4] Gutiérrez—Cuevas J, Santos A, Armendariz—Borunda J. Pathophysiological molecular mechanisms of obesity: a link between MAFLD and NASH with cardiovascular diseases. Int J Mol Sci. 2021; 22(21):11629. https://doi.org/10.3390/ijms222111629.

[5] Quek J, Chan KE, Wong ZY, et al. Global prevalence of non—alcoholic fatty liver disease and non—alcoholic steatohepatitis in the overweight and obese population: a systematic review and meta—analysis. Lancet Gastroenterol Hepatol. 2023; 8(1):20-30. https://doi.org/10.1016/S2468—1253(22)00317—X.

[6] Lebeaupin C, Vallée D, Hazari Y, et al. Endoplasmic reticulum stress signalling and the pathogenesis of non—alcoholic fatty liver disease. J Hepatol. 2018; 69(4):927-947. https://doi.org/10.1016/j.jhep.2018.06.008.

[7] Baiceanu A, Mesdom P, Lagouge M, et al. Endoplasmic reticulum proteostasis in hepatic steatosis. Nat Rev Endocrinol. 2016;12(12):710-722. https://doi.org/10.1038/nrendo.2016.124.

[8] Ajoolabady A, Kaplowitz N, Lebeaupin C, et al. Endoplasmic reticulum stress in liver diseases. Hepatology. 2023; 77(2):619-639. https://doi.org/10.1002/hep.32562.

[9] Harada Y, Ohkawa Y, Maeda K, et al. Glycan quality control in and out of the endoplasmic reticulum of mammalian cells. FEBS J. 2022; 289(22):7147-7162. https://doi.org/10.1111/febs.16185.

[10] Clarke JD, Novak P, Lake AD, et al. Impaired N—linked glycosylation of uptake and efflux transporters in human non—alcoholic fatty liver disease. Liver Int. 2017; 37(7):1074-1081. https://doi.org/10.1111/liv.13362.

[11] Chung CY, Majewska NI, Wang Q, et al. SnapShot: N—glycosylation processing pathways across kingdoms. Cell. 2017; 171(1):258-258.e1. https://doi.org/10.1016/j.cell.2017.09.014.

[12] Ramírez AS, Kowal J, Locher KP. Cryo—electron microscopy structures of human oligosaccharyltransferase complexes OST—A and OST—B. Science. 2019; 366(6471):1372-1375. https://doi.org/10.1126/science.aaz3505.

[13] Ruiz—Canada C, Kelleher DJ, Gilmore R. Cotranslational and posttranslational N—glycosylation of polypeptides by distinct mammalian OST isoforms. Cell. 2009; 136(2):272-283. https://doi.org/10.1016/j.cell.2008.11.047.

[14] Cavalcanti GV, de Oliveira FR, Bannitz RF, et al. Endoplasmic reticulum stress in the salivary glands of patients with primary and associated Sjögren’s disease, and non—Sjögren’s sicca syndrome: a comparative analysis and the influence of chloroquine. Adv Rheumatol. 2025; 65(2):1-11. https://doi.org/10.1186/s42358—024—00430—7.

[15] Chang J, Yang Q, Liu X, et al. Dihydroartemisinin inhibits ATP6 activity, reduces energy metabolism of hepatocellular carcinoma cells, promotes apoptosis and inhibits metastasis via CANX. Oncol Lett. 2024; 28(4):474. https://doi.org/10.3892/ol.2024.14607.

[16] Walter P, Ron D. The unfolded protein response: from stress pathway to homeostatic regulation. Science. 2011; 334(6059):1081-1086. https://doi.org/10.1126/science.1209038.

[17] Wang C, Cui Q, Du R, et al. Expression of G3BP1 in benign and malignant human prostate tissues. Transl Androl Urol. 2021; 10(4):1665-1675. https://doi.org/10.21037/tau—20—1450.

[18] Ge Y, Jin J, Li J, et al. The roles of G3BP1 in human diseases. Gene. 2022; 821:146294. https://doi.org/10.1016/j.gene.2022.146294.

[19] Aulas A, Caron G, Gkogkas CG, et al. G3BP1 promotes stress—induced RNA granule interactions to preserve polyadenylated mRNA. J Cell Biol. 2015; 209(1):73-84. https://doi.org/10.1083/jcb.201408092.

[20] Yang P, Mathieu C, Kolaitis RM, et al. G3BP1 is a tunable switch that triggers phase separation to assemble stress granules. Cell. 2020; 181(2):325-345. https://doi.org/10.1016/j.cell.2020.03.046.

[21] Zhang M, Yang C, Zhu M, et al. Saturated fatty acids entrap PDX1 in stress granules and impede islet beta cell function. Diabetologia. 2021; 64(5):1144-1157. https://doi.org/10.1007/s00125—021—05389—4.

[22] Amen T, Kaganovich D. Stress granules inhibit fatty acid oxidation by modulating mitochondrial permeability. Cell Rep. 2021; 35(11):109237. https://doi.org/10.1016/j.celrep.2021.109237.

[23] Lin L, Dong Y, Yang B, et al. Chemical constituents and biological activity of Chinese medicinal herb ‘Xihuangcao’. Comb Chem High Throughput Screen. 2011; 14(8):720-729. https://doi.org/10.2174/138620711796504352.

[24] Li S, Liang F, Huang D, et al. Diterpenoids from the aerial parts of Isodon serra with selective cytotoxic activity. Molecules. 2024; 29(12):2733. https://doi.org/10.3390/molecules29122733.

[25] Liu X, Bian Z, Tian Y, et al. Six new diterpenoids with anti—inflammatory and cytotoxic activity from Isodon serra. Fitoterapia. 2024; 176:106019. https://doi.org/10.1016/j.fitote.2024.106019.

[26] Zhang J, Yan J, Dong H, et al. Dimeric sesquiterpenoids with anti—inflammatory activities from Inula britannica. Chin J Nat Med. 2025; 23(8):961-971. https://doi.org/10.1016/S1875—5364(25)60931—9.

[27] Zhou H, Han M, Nan M, et al. Isodons AH, seco—abietane and abietane—type diterpenoids from Isodon lophanthoides: isolation, structural elucidation, and anticholestatic activity. Chin J Nat Med. 2025; 23(9):1133-1142. https://doi.org/10.1016/S1875—5364(25)60977—0.

[28] Lin CZ, Zhao W, Feng XL, et al. Cytotoxic diterpenoids from Rabdosia lophanthoides var. gerardianus. Fitoterapia. 2016; 109:14-19. https://doi.org/10.1016/j.fitote.2015.11.015.

[29] Feng F, Zhang W, Cao Y, et al. Combining label—free quantitative proteomics and 2D—DIGE to identify the potential targets of Sini decoction acting on myocardial infarction. Chin J Nat Med. 2025; 23(8):1016-1024. https://doi.org/10.1016/S1875—5364(25)60937—X.

[30] Li S, Xu F, Yu L, et al. Stigmasterol protects human brain microvessel endothelial cells against ischemia—reperfusion injury through suppressing EPHA2 phosphorylation. Chin J Nat Med. 2023; 21(2):127-135. https://doi.org/10.1016/S1875—5364(23)60390—5.

[31] Dolicka D, Foti M, Sobolewski C. The emerging role of stress granules in hepatocellular carcinoma. Int J Mol Sci. 2021; 22(17):9428. https://doi.org/10.3390/ijms22179428.

[32] Guay KP, Ke H, Canniff NP, et al. ER chaperones use a protein folding and quality control glyco—code. Mol Cell. 2023; 83(24):4524-4537.e5. https://doi.org/10.1016/j.molcel.2023.11.006.

[33] Fang MY, Markmiller S, Vu AQ, et al. Small—molecule modulation of TDP—43 recruitment to stress granules prevents persistent TDP—43 accumulation in ALS/FTD. Neuron. 2019; 103(5):802-819. https://doi.org/10.1016/j.neuron.2019.05.048.

[34] Cui Q, Bi H, Lv Z, et al. Diverse CMT2 neuropathies are linked to aberrant G3BP interactions in stress granules. Cell. 2023; 186(4):803-820. https://doi.org/10.1016/j.cell.2022.12.046.

[35] Markmiller S, Soltanieh S, Server KL, et al. Context—dependent and disease—specific diversity in protein interactions within stress granules. Cell. 2018; 172(3):590-604. https://doi.org/10.1016/j.cell.2017.12.032.

[36] Shrimal S, Cherepanova NA, Gilmore R. DC2 and KCP2 mediate the interaction between the oligosaccharyltransferase and the ER translocon. J Cell Biol. 2017; 216(11):3625-3638. https://doi.org/10.1083/jcb.201702159.

[37] Zhang J, Wang B, Gao X, et al. RNF185 regulates proteostasis in Ebolavirus infection by crosstalk between the calnexin cycle, ERAD, and reticulophagy. Nat Commun. 2022; 13(1):6007. https://doi.org/10.1038/s41467—022—33805—9.

[38] Xie Z, Zhao S, Tu Y, et al. Proteasome resides in and dismantles plant heat stress granules constitutively. Mol Cell. 2024; 84(17):3320-3335. https://doi.org/10.1016/j.molcel.2024.07.033.

[39] Anderson P, Kedersha N. RNA granules: post—transcriptional and epigenetic modulators of gene expression. Nat Rev Mol Cell Biol. 2009; 10(6):430-436. https://doi.org/10.1038/nrm2694.

[40] Gal J, Chen J, Na DY, et al. The acetylation of lysine—376 of G3BP1 regulates RNA binding and stress granule dynamics. Mol Cell Biol. 2019; 39(22):e00052-19. https://doi.org/10.1128/MCB.00052—19.

[41] Luo Z, Yin F, Wang X, et al. Progress in approved drugs from natural product resources. Chin J Nat Med. 2024; 22(3):195-211. https://doi.org/10.1016/S1875—5364(24)60582—0.

[42] Liu L, Liu Y, Zhang S, et al. Celastrol promotes apoptosis of breast cancer MDA—MB—231 cells by targeting HSDL2. Acupunct Herb Med. 2024; 4(1):92-101. https://doi.org/10.1097/HM9.0000000000000102.

[43] Sun CP, Zhou JJ, Yu ZL, et al. Kurarinone alleviated Parkinson’s disease via stabilization of epoxyeicosatrienoic acids in animal model. Proc Natl Acad Sci USA. 2022; 119(9):e2118818119. https://doi.org/10.1073/pnas.2118818119.

[44] Zhang J, Luan ZL, Huo XK, et al. Direct targeting of sEH with alisol B alleviated the apoptosis, inflammation, and oxidative stress in cisplatin—induced acute kidney injury. Int J Biol Sci. 2023; 19(1):294-310. https://doi.org/10.7150/ijbs.78097.

[45] Feng YL, Xu XR, Zhu QM, et al. Aucklandiae radix targeted PKM2 to alleviate ulcerative colitis: insights from the photocrosslinking target fishing technique. Phytomedicine. 2024; 134:155973. https://doi.org/10.1016/j.phymed.2024.155973.

[46] Zhang CH, Wang JX, Cai ML, et al. The roles and mechanisms of G3BP1 in tumour promotion. J Drug Target. 2019; 27(3):300-305. https://doi.org/10.1080/1061186X.2018.1523415.

[47] Omer A, Barrera MC, Moran JL, et al. G3BP1 controls the senescence—associated secretome and its impact on cancer progression. Nat Commun. 2020; 11(1):4979. https://doi.org/10.1038/s41467—020—18734—9.

[48] Wang Y, Fu D, Chen Y, et al. G3BP1 promotes tumor progression and metastasis through IL—6/G3BP1/STAT3 signaling axis in renal cell carcinomas. Cell Death Dis. 2018; 9(5):501. https://doi.org/10.1038/s41419—018—0504—2.

[49] Cherepanova N, Shrimal S, Gilmore R. N—linked glycosylation and homeostasis of the endoplasmic reticulum. Curr Opin Cell Biol. 2016; 41:57-65. https://doi.org/10.1016/j.ceb.2016.03.021.

[50] Ochoa—Rios S, O’Connor IP, Kent LN, et al. Imaging mass spectrometry reveals alterations in N—linked glycosylation that are associated with histopathological changes in nonalcoholic steatohepatitis in mouse and human. Mol Cell Proteomics. 2022; 21(5):100225. https://doi.org/10.1016/j.mcpro.2022.100225.

[51] Prentzell MT, Rehbein U, Sandoval MC, et al. G3BPs tether the TSC complex to lysosomes and suppress mTORC1 signaling. Cell. 2021; 184(3):655-674.e27. https://doi.org/10.1016/j.cell.2020.12.024.

[52] Ortega ÁD, Willers IM, Sala S, et al. Human G3BP1 interacts with β—F1—ATPase mRNA and inhibits its translation. J Cell Sci. 2010; 123(16):2685-2696. https://doi.org/10.1242/jcs.065920.

[53] Liu S, Zhang X, Yao X, et al. Mammalian IRE1α dynamically and functionally coalesces with stress granules. Nat Cell Biol. 2024; 26(6):917-931. https://doi.org/10.1038/s41556—024—01418—7.