Gut Microbiota Regulate Lipid Metabolism via the Bile Acid Pathway: Resistance to Hypoxia in Gansu Zokor (Eospalax cansus)

Abstract

The Gansu zokor (Eospalax cansus), a subterranean rodent endemic to the Loess Plateau of China, exhibits remarkable adaptability to hypoxic environments. While gut microbiota are known to regulate lipid metabolism through bile acid (BA) pathways, this phenomenon has not been investigated in subterranean rodents exposed to hypoxia. This study employed 16SrRNA sequencing, targeted analysis of BA metabolites in colonic contents, and assessments of BA and lipid metabolites alongside molecular analyses in the liver and ileum under conditions of acute and chronic hypoxia in Gansu zokors. The results revealed that hypoxia altered the composition of gut microbiota and BA pools in Gansu zokors. Hypoxia-induced changes increased the abundance of gut microbiota associated with BA metabolism, thereby modulating lipid metabolism via farnesoid X receptor (FXR) signaling in the distal ileum and liver cells. Under acute hypoxia, FXR upregulated lipid synthesis and suppressed fatty acid β-oxidation by downregulating the carnitine palmitoyl-transferase1A (CPT1A) expression. Conversely, during chronic hypoxia, particularly under long-term exposure, FXR reduced lipid synthesis and enhanced fatty acid β-oxidation by upregulating acyl-CoA oxidase (ACOX1) expression. In both hypoxic conditions, FXR facilitated lipoprotein metabolism. In summary, this study elucidates that gut microbiota–mediated BA metabolic pathways contribute to the Gansu zokor's ability to maintain lipid metabolic homeostasis and adaptation to hypoxia.

Keywords

bile acid (BA) / Gansu zokor (Eospalax cansus) / gut microbiota / hypoxia / lipid metabolism

References

[1] Ackerman, D., and M. C. Simon. 2014. “Hypoxia, Lipids, and Cancer: Surviving the Harsh Tumor Microenvironment.” Trends in Cell Biology 24: 472-478.

[2] Ar, A., R. Arieli, and A. Shkolnik. 1977. “Blood-gas Properties and Function in the Fossorial Mole Rat Under Normal and Hypoxic-Hypercapnic Atmospheric Conditions.” Respiration Physiology 30: 201-219.

[3] Arieli, R., and E. Nevo. 1991. “Hypoxic Survival Differs Between Two Mole Rat Species (Spalax ehrenbergi) of Humid and Arid Habitats.” Comparative Biochemistry and Physiology A Comparative Physiology 100: 543-545.

[4] Bai, X., G. Liu, J. Yang, et al. 2022. “Changes in the Gut Microbiota of Rats in High-Altitude Hypoxic Environments.” Microbiology Spectrum 10: e0162622.

[5] Ben Salah, R., I. Trabelsi, K. Hamden, H. Chouayekh, and S. Bejar. 2013. “Lactobacillus plantarum TN8 Exhibits Protective Effects on Lipid, Hepatic and Renal Profiles in Obese Rat.” Anaerobe 23: 55-61.

[6] Botham, K. M., and G. S. Boyd. 1983. “The Metabolism of Chenodeoxycholic Acid to Beta-Muricholic Acid in Rat Liver.” European Journal of Biochemistry 134: 191-196.

[7] Boutilier, R. G.2001. “Mechanisms of Cell Survival in Hypoxia and Hypothermia.” The Journal of Experimental Biology 204: 3171-3181.

[8] Burgomaster, K. A., K. R. Howarth, S. M. Phillips, et al. 2008. “Similar Metabolic Adaptations During Exercise After Low Volume Sprint Interval and Traditional Endurance Training in Humans.” The Journal of Physiology 586: 151-160.

[9] Chen, M. J., C. Liu, Y. Wan, et al. 2021. “Enterohepatic Circulation of Bile Acids and Their Emerging Roles on Glucolipid Metabolism.” Steroids 165: 108757.

[10] Chevalier, C., O. Stojanović, D. J. Colin, et al. 2015. “Gut Microbiota Orchestrates Energy Homeostasis During Cold.” Cell 163: 1360-1374.

[11] Chiang, J. Y.2013. “Bile Acid Metabolism and Signaling.” Comprehensive Physiology 3: 1191-1212.

[12] Choi, K., M. Jin, C. C. Zouboulis, and Y. Lee. 2021. “Increased Lipid Accumulation Under Hypoxia in SZ95 Human Sebocytes.” Dermatology 237: 131-141.

[13] Cui, Y., C. Guo, Z. Xia, et al. 2023. “Exploring the Therapeutic Potential of a Nano Micelle Containing a Carbon Monoxide-Releasing Molecule for Metabolic-Associated Fatty Liver Disease by Modulating Hypoxia-Inducible Factor-1α.” Acta Biomaterialia 169: 500-516.

[14] Currie, E., A. Schulze, R. Zechner, T. C. Walther, and R. V. Farese . 2013. “Cellular Fatty Acid Metabolism and Cancer.” Cell Metabolism 18: 153-161.

[15] de la Rosa Rodriguez, M. A., L. Deng, A. Gemmink, et al. 2021. “Hypoxia-Inducible Lipid Droplet-Associated Induces DGAT1 and Promotes Lipid Storage in Hepatocytes.” Molecular Metabolism 47: 101168.

[16] Dong, Q., L. Shi, Y. Li, et al. 2018. “Differential Responses of Lasiopodomys mandarinus and Lasiopodomys brandtii to Chronic Hypoxia: A Cross-Species Brain Transcriptome Analysis.” BMC Genomics [Electronic Resource] 19: 901.

[17] Fang, X., I. Seim, Z. Huang, et al. 2014. “Adaptations to a Subterranean Environment and Longevity Revealed by the Analysis of Mole Rat Genomes.” Cell Reports 8: 1354-1364.

[18] Farhat, E., M. E. M. Devereaux, M. E. Pamenter, and J. M. Weber. 2020. “Naked Mole-Rats Suppress Energy Metabolism and Modulate Membrane Cholesterol in Chronic Hypoxia.” American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 319: R148-R155.

[19] Feingold, K. R.2000. Introduction to Lipids and Lipoproteins. Endotext [Internet], South Dartmouth, MA.

[20] Guppy, M., and P. Withers. 1999. “Metabolic Depression in Animals: Physiological Perspectives and Biochemical Generalizations.” Biological Reviews of the Cambridge Philosophical Society 74: 1-40.

[21] Handelman, S. K., Y. M. Puentes, A. Kuppa, et al. 2022. “Population-Based Meta-Analysis and Gene-Set Enrichment Identifies FXR/RXR Pathway as Common to Fatty Liver Disease and Serum Lipids.” Hepatology Communications 6: 3120-3131.

[22] Hao, Z., L. Xu, L. Zhao, J. He, G. Li, and J. Li. 2021. “Transcriptome Analysis of the Liver of Eospalax fontanierii Under Hypoxia.” PeerJ 9: e11166.

[23] Hernandez, G. V., V. A. Smith, M. Melnyk, et al. 2020. “Dysregulated FXR-FGF19 Signaling and Choline Metabolism Are Associated with Gut Dysbiosis and Hyperplasia in a Novel Pig Model of Pediatric NASH.” American Journal of Physiology. Gastrointestinal and Liver Physiology 318: G582-g609.

[24] Herrema, H., M. Meissner, T. H. van Dijk, et al. 2010. “Bile Salt Sequestration Induces Hepatic De Novo Lipogenesis Through Farnesoid X Receptor- and Liver X Receptor Alpha-Controlled Metabolic Pathways in Mice.” Hepatology (Baltimore, Md.) 51: 806-816.

[25] Hirokane, H., M. Nakahara, S. Tachibana, M. Shimizu, and R. Sato. 2004. “Bile Acid Reduces the Secretion of Very Low Density Lipoprotein by Repressing Microsomal Triglyceride Transfer Protein Gene Expression Mediated by Hepatocyte Nuclear Factor-4.” The Journal of Biological Chemistry 279: 45685-45692.

[26] Hochachka, P. W.1986. “Defense Strategies Against Hypoxia and Hypothermia.” Science 231: 234-241.

[27] Hochachka, P. W., L. T. Buck, C. J. Doll, and S. C. Land. 1996. “Unifying Theory of Hypoxia Tolerance: Molecular/Metabolic Defense and Rescue Mechanisms for Surviving Oxygen Lack.” Proceedings of the National Academy of Sciences of the United States of America 93: 9493-9498.

[28] Hooper, A. J., J. R. Burnett, and G. F. Watts. 2015. “Contemporary Aspects of the Biology and Therapeutic Regulation of the Microsomal Triglyceride Transfer Protein.” Circulation Research 116: 193-205.

[29] Houten, S. M., S. Violante, F. V. Ventura, and R. J. Wanders. 2016. “The Biochemistry and Physiology of Mitochondrial Fatty Acid β-Oxidation and Its Genetic Disorders.” Annual Review of Physiology 78: 23-44.

[30] Hu, B., J. Wang, Y. Li, et al. 2023. “Gut Microbiota Facilitates Adaptation of the Plateau Zokor (Myospalax baileyi) to the Plateau Living Environment.” Frontiers in Microbiology 14: 1136845.

[31] Irshad, R., S. Tabassum, and M. Husain. 2023. “Aberrant Lipid Metabolism in Cancer: Current Status and Emerging Therapeutic Perspectives.” Current Topics in Medicinal Chemistry 23: 1090-1103.

[32] Johnson, P. R.2008. “Down-Regulation of Bile Acid Synthesis and a Metabolic Co-Activator Under Hypoxic Conditions—Implications in Obstructive Sleep Apnea.” Medical Hypotheses 71: 530-536.

[33] Kanda, T., I. Niot, L. Foucaud, et al. 1996. “Effect of Bile on the Intestinal Bile-Acid Binding Protein (I-BABP) Expression. In Vitro and in Vivo Studies.” FEBS Letters 384: 131-134.

[34] Kosters, A., and S. J. Karpen. 2008. “Bile Acid Transporters in Health and Disease.” Xenobiotica; The Fate of Foreign Compounds in Biological Systems 38: 1043-1071.

[35] Lazaridis, K. N., L. Pham, P. Tietz, et al. 1997. “Rat Cholangiocytes Absorb Bile Acids at Their Apical Domain via the Ileal Sodium-Dependent Bile Acid Transporter.” The Journal of Clinical Investigation 100: 2714-2721.

[36] Lefebvre, P., B. Cariou, F. Lien, F. Kuipers, and B. Staels. 2009. “Role of Bile Acids and Bile Acid Receptors in Metabolic Regulation.” Physiological Reviews 89: 147-191.

[37] Li, F., Z. Qiao, Q. Duan, and E. Nevo. 2021. “Adaptation of Mammals to Hypoxia.” Animal Models and Experimental Medicine 4: 311-318.

[38] Li, M., Y. Peng, W. Chen, et al. 2023. “Active Nrf2 Signaling Flexibly Regulates HO-1 and NQO-1 in Hypoxic Gansu zokor (Eospalax cansus).” Comparative Biochemistry and Physiology Part B: Biochemistry & Molecular Biology 264: 110811.

[39] Li, X., and T. Wang. 1992. “Studies on the Population Age of Gansu Zokor.” Acta Theriologica Sinica 12: 193.

[40] Li, Y., J. Li, P. Cao, and Y. Liu. 2020. “Sinapine-Enriched Rapeseed Oils Reduced Fatty Liver Formation in High-Fat Diet-Fed C57BL/6J Mice.” RSC Advances 10: 21248-21258.

[41] Liang, Z., H. He, B. Zhang, Z. Kai, and L. Zong. 2024. “Hypoxia Expedites the Progression of Papillary Thyroid Carcinoma by Promoting the CPT1A-Mediated Fatty Acid Oxidative Pathway.” Drug Development Research 85: e22168.

[42] Lin, J., L. Fan, Y. Han, et al. 2021. “The mTORC1/eIF4E/HIF-1α Pathway Mediates Glycolysis to Support Brain Hypoxia Resistance in the Gansu zokor, Eospalax cansus.” Frontiers in Physiology 12: 626240.

[43] Lin, J., Q. Yang, J. Guo, et al. 2022. “Gut Microbiome Alterations and Hepatic Metabolic Flexibility in the Gansu zokor, Eospalax cansus: Adaptation to Hypoxic Niches.” Frontiers in Cardiovascular Medicine 9: 814076.

[44] Liu, D., P. Song, J. Yan, et al. 2021. “Gut Microbiome Changes in Captive Plateau Zokors (Eospalax baileyi).” Evolutionary Bioinformatics Online 17: 1176934321996353.

[45] Luo, M., T. Li, and H. Sang. 2023. “The Role of Hypoxia-Inducible Factor 1α in Hepatic Lipid Metabolism.” Journal of Molecular Medicine 101: 487-500.

[46] Madon, J., U. Eckhardt, T. Gerloff, B. Stieger, and P. J. Meier. 1997. “Functional Expression of the Rat Liver Canalicular Isoform of the Multidrug Resistance-Associated Protein.” FEBS Letters 406: 75-78.

[47] Makishima, M., A. Y. Okamoto, J. J. Repa, et al. 1999. “Identification of a Nuclear Receptor for Bile Acids.” Science 284: 1362-1365.

[48] Mesarwi, O. A., R. Loomba, and A. Malhotra. 2019. “Obstructive Sleep Apnea, Hypoxia, and Nonalcoholic Fatty Liver Disease.” American Journal of Respiratory and Critical Care Medicine 199: 830-841.

[49] Moeller, A. H., and J. G. Sanders. 2020. “Roles of the Gut Microbiota in the Adaptive Evolution of Mammalian Species.” Philosophical Transactions of the Royal Society B Biological Sciences 375: 20190597.

[50] Nevo, E.2013. “Stress, Adaptation, and Speciation in the Evolution of the Blind Mole Rat, Spalax, in Israel.” Molecular Phylogenetics and Evolution 66: 515-525.

[51] Nguyen, P., V. Leray, M. Diez, et al. 2008. “Liver Lipid Metabolism.” Journal of Animal Physiology and Animal Nutrition 92: 272-283.

[52] Out, C., J. Hageman, V. W. Bloks, et al. 2011. “Liver Receptor Homolog-1 Is Critical for Adequate Up-Regulation of Cyp7a1 Gene Transcription and Bile Salt Synthesis During Bile Salt Sequestration.” Hepatology 53: 2075-2085.

[53] Parks, D. J., S. G. Blanchard, R. K. Bledsoe, et al. 1999. “Bile Acids: Natural Ligands for an Orphan Nuclear Receptor.” Science 284: 1365-1368.

[54] Pineda Torra, I., T. Claudel, C. Duval, V. Kosykh, J. C. Fruchart, and B. Staels. 2003. “Bile Acids Induce the Expression of the Human Peroxisome Proliferator-Activated Receptor α Gene via Activation of the Farnesoid X Receptor.” Molecular Endocrinology 17: 259-272.

[55] Preidis, G. A., K. H. Kim, and D. D. Moore. 2017. “Nutrient-Sensing Nuclear Receptors PPARα and FXR Control Liver Energy Balance.” The Journal of Clinical Investigation 127: 1193-1201.

[56] Ridaura, V. K., J. J. Faith, F. E. Rey, et al. 2013. “Gut Microbiota from Twins Discordant for Obesity Modulate Metabolism in Mice.” Science 341: 1241214.

[57] Salaj, R., J. Stofilová, A. Soltesová, et al. 2013. “The Effects of Two Lactobacillus plantarum Strains on Rat Lipid Metabolism Receiving a High Fat Diet.” The Scientific World Journal 2013: 135142.

[58] Sayin, S. I., A. Wahlström, J. Felin, et al. 2013. “Gut Microbiota Regulates Bile Acid Metabolism by Reducing the Levels of Tauro-beta-muricholic Acid, a Naturally Occurring FXR Antagonist.” Cell Metabolism 17: 225-235.

[59] Schlaepfer, I. R., and M. Joshi. 2020. “CPT1A-mediated Fat Oxidation, Mechanisms, and Therapeutic Potential.” Endocrinology 161: bqz046.

[60] Schoeler, M., and R. Caesar. 2019. “Dietary Lipids, Gut Microbiota and Lipid Metabolism.” Reviews in Endocrine & Metabolic Disorders 20: 461-472.

[61] Selwyn, F. P., I. L. Csanaky, Y. Zhang, and C. D. Klaassen. 2015. “Importance of Large Intestine in Regulating Bile Acids and Glucagon-Like Peptide-1 in Germ-free Mice.” Drug Metabolism and Disposition: The Biological Fate of Chemicals 43: 1544-1556.

[62] Shams, I., A. Avivi, and E. Nevo. 2005. “Oxygen and Carbon Dioxide Fluctuations in Burrows of Subterranean Blind Mole Rats Indicate Tolerance to Hypoxic-Hypercapnic Stresses.” Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 142: 376-382.

[63] Spriet, L. L.2014. “New Insights into the Interaction of Carbohydrate and Fat Metabolism During Exercise.” Sports Medicine (Auckland, N.Z.) 44, no. Suppl 1: S87-96.

[64] Su, Q., D. H. Zhuang, Y. C. Li, et al. 2024. “Gut Microbiota Contributes to High-Altitude Hypoxia Acclimatization of Human Populations.” Genome Biology 25: 232.

[65] Sun, J., J. Fan, T. Li, X. Yan, and Y. Jiang. 2022. “Nuciferine Protects Against High-Fat Diet-Induced Hepatic Steatosis via Modulation of Gut Microbiota and Bile Acid Metabolism in Rats.” Journal of Agricultural and Food Chemistry 70: 12014-12028.

[66] Sun, W., T. Nie, K. Li, et al. 2021. “Hepatic CPT1A Facilitates Liver-Adipose Cross-Talk via Induction of FGF21 in Mice.” Diabetes 71: 31-42.

[67] Sundaram, S. S., A. Halbower, Z. Pan, et al. 2016. “Nocturnal Hypoxia-Induced Oxidative Stress Promotes Progression of Pediatric Non-Alcoholic Fatty Liver Disease.” Journal of Hepatology 65: 560-569.

[68] Wahlström, A., S. I. Sayin, H. U. Marschall, and F. Bäckhed. 2016. “Intestinal Crosstalk Between Bile Acids and Microbiota and Its Impact on Host Metabolism.” Cell Metabolism 24: 41-50.

[69] Wang, F., J. Zou, H. Xu, et al. 2022. “Effects of Chronic Intermittent Hypoxia and Chronic Sleep Fragmentation on Gut Microbiome, Serum Metabolome, Liver and Adipose Tissue Morphology.” Frontiers in Endocrinology 13: 820939.

[70] Wang, H., J. Chen, K. Hollister, L. C. Sowers, and B. M. Forman. 1999. “Endogenous Bile Acids Are Ligands for the Nuclear Receptor FXR/BAR.” Molecular Cell 3: 543-553.

[71] Wu, J. X., Q. He, Y. Zhou, et al. 2023. “Protective Effect and Mechanism of Lactoferrin Combined with Hypoxia Against High-Fat Diet Induced Obesity and Non-Alcoholic Fatty Liver Disease in Mice.” International Journal of Biological Macromolecules 227: 839-850.

[72] Wu, Y., Q. Zhang, Y. Ren, and Z. Ruan. 2017. “Effect of Probiotic Lactobacillus on Lipid Profile: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials.” PLoS ONE 12: e0178868.

[73] Xie, H., C. H. Tang, J. H. Song, et al. 2018. “IRE1α RNase-Dependent Lipid Homeostasis Promotes Survival in Myc-Transformed Cancers.” The Journal of Clinical Investigation 128: 1300-1316.

[74] Xing, J., Y. Ying, C. Mao, et al. 2018. “Hypoxia Induces Senescence of Bone Marrow Mesenchymal Stem Cells via Altered Gut Microbiota.” Nature Communications 9: 2020.

[75] Yan, T., W. Fan, and J. He. 2012. “The Effect of Hypoxia Tolerance on Cardiac Muscle Structure of Gansu Zokor (Myospalax cansus).” Journal of Shaanxi Normal University 40: 62-66.

[76] Yang, W., X. Ling, S. He, et al. 2023. “PPARα/ACOX1 as a Novel Target for Hepatic Lipid Metabolism Disorders Induced by Per- and Polyfluoroalkyl Substances: an Integrated Approach.” Environment International 178: 108138.

[77] Yoldas Celik, M., E. Canda, H. Yazici, et al. 2024. “Long-Term Clinical Outcomes and Management of Hypertriglyceridemia in Children with Apo-CII Deficiency.” Nutrition, Metabolism, and Cardiovascular Diseases: NMCD 34: 1798-1806.

[78] Zhang, S. D., G. H. Lin, J. R. Han, et al. 2022. “Digestive Tract Morphology and Gut Microbiota Jointly Determine an Efficient Digestive Strategy in Subterranean Rodents: Plateau zokor.” Animals: An Open Access Journal from MDPI 12: 2155.

[79] Zhang, T., Q. Zhao, X. Xiao, et al. 2019. “Modulation of Lipid Metabolism by Celastrol.” Journal of Proteome Research 18: 1133-1144.

[80] Zhang, Y., L. W. Castellani, C. J. Sinal, F. J. Gonzalez, and P. A. Edwards. 2004. “Peroxisome Proliferator-activated Receptor-γ Coactivator 1α (PGC-1α) Regulates Triglyceride Metabolism by Activation of the Nuclear Receptor FXR.” Genes & Development 18: 157-169.

[81] Zhu, K., D. Ge, Z. Wen, L. Xia, and Q. Yang. 2018. “Evolutionary Genetics of Hypoxia and Cold Tolerance in Mammals.” Journal of Molecular Evolution 86: 618-634.

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