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FXR Receptor, (aka NR1H4) - Induced By Reishi!

Updated: Oct 30, 2023

Some interesting research on a receptor (FXR/NR1H4) that supports the liver, bile, the bile salt export pump (BSEP/ABCB11) and Glut4 (what!) yep the same GLUT4 that modulates blood sugar.


Folks with compromised NR1H4, liver congestion, blood sugar issues, may find the below research interesting related to Reishi. However, mushrooms, like other things can also cause neuro over excitation, especially those with NMDA and or AHR receptor issues.


Equally as important , is that Reishi induced CYP7A1:).


"The bile acid receptor (BAR), also known as farnesoid X receptor (FXR) or NR1H4 (nuclear receptor subfamily 1, group H, member 4), is a nuclear receptor that is encoded by the NR1H4 gene in humans.[5][6]


FXR is expressed at high levels in the liver and intestine. Chenodeoxycholic acid and other bile acids are natural ligands for FXR. Similar to other nuclear receptors, when activated, FXR translocates to the cell nucleus, forms a dimer (in this case a heterodimer with RXR) and binds to hormone response elements on DNA, which up- or down-regulates the expression of certain genes.[6]

One of the primary functions of FXR activation is the suppression of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis from cholesterol. FXR does not directly bind to the CYP7A1 promoter. Rather, FXR induces expression of small heterodimer partner (SHP), which then functions to inhibit transcription of the CYP7A1 gene. In this way, a negative feedback pathway is established in which synthesis of bile acids is inhibited when cellular levels are already high.

The absence of FXR in an FXR-/- mouse model led to increased bile acids in the liver, and the spontaneous development of liver tumors.[7] Reducing the pool of bile acids in the FXR-/- mice by feeding the bile acid sequestering resin cholestyramine reduced the number and size of the malignant lesions.

FXR has also been found to be important in regulation of hepatic triglyceride levels.[8] Specifically, FXR activation suppresses lipogenesis and promotes free fatty acid oxidation by PPARα activation.[8] Studies have also shown the FXR to regulate the expression and activity of epithelial transport proteins involved in fluid homeostasis in the intestine, such as the cystic fibrosis transmembrane conductance regulator (CFTR).[9]

Activation of FXR in diabetic mice reduces plasma glucose and improves insulin sensitivity, whereas inactivation of FXR has the opposite effect.[8]


Farnesoid X receptor has been shown to interact with:

  • Peroxisome proliferator-activated receptor gamma coactivator 1-alpha[10] and

  • Retinoid X receptor alpha.[11]

"GLUT4, the main insulin-responsive glucose transporter, plays a critical role in maintaining systemic glucose homeostasis and is subject to complicated metabolic regulation. GLUT4 expression disorder might cause insulin resistance, and over-expression of GLUT4 has been confirmed to ameliorate diabetes. Here, we reported that farnesoid X receptor (FXR) and its agonist chenodeoxycholic acid (CDCA) could induce GLUT4 transcription in 3T3-L1 and HepG2 cells. Furthermore, CDCA could increase the GLUT4 protein amount in C57BL/6J mice sex-dependently. The following progressive 5'-deletion analysis and site-mutation investigation further suggested that FXR could induce GLUT4 expression through FXR response element (FXRE) in the GLUT4 promoter. EMSA and knock-down of retinoid X receptor (RXR) indicated that FXR binds to the GLUT4-FXRE as a monomer and RXR does not participate in the FXR stimulation of GLUT4 expression. In addition, we demonstrated that FXR does not interfere with insulin-induced GLUT4 translocation to plasma membrane. All these data thereby implied that FXR is a new transcription factor of GLUT4, further elucidating the potential role for FXR in glucose metabolism."[19]


"Farnesoid X Receptor plays an important role in maintaining bile acid, cholesterol homeostasis and glucose metabolism. Here we investigated whether FXR is expressed by pancreatic β-cells and regulates insulin signaling in pancreatic β-cell line and human islets. We found that FXR activation induces positive regulatory effects on glucose-induced insulin transcription and secretion by genomic and non-genomic activities. Genomic effects of FXR activation relay on the induction of the glucose regulated transcription factor KLF11. Indeed, results from silencing experiments of KLF11 demonstrate that this transcription factor is essential for FXR activity on glucose-induced insulin gene transcription. In addition FXR regulates insulin secretion by non-genomic effects. Thus, activation of FXR in βTC6 cells increases Akt phosphorylation and translocation of the glucose transporter GLUT2 at plasma membrane, increasing the glucose uptake by these cells. In vivo experiments on Non Obese Diabetic (NOD) mice demonstrated that FXR activation delays development of signs of diabetes, hyperglycemia and glycosuria, by enhancing insulin secretion and by stimulating glucose uptake by the liver. These data established that an FXR-KLF11 regulated pathway has an essential role in the regulation of insulin transcription and secretion induced by glucose."[20]


Reishi to the Rescue:

"Background/aims: Non-alcoholic fatty liver disease (NAFLD) encompasses a series of pathologic changes ranging from steatosis to steatohepatitis, which may progress to cirrhosis and hepatocellular carcinoma. The purpose of this study was to determine whether ganoderma lucidum polysaccharide peptide (GLPP) has therapeutic effect on NAFLD.

Methods: Ob/ ob mouse model and ApoC3 transgenic mouse model were used for exploring the effect of GLPP on NAFLD. Key metabolic pathways and enzymes were identified by metabolomics combining with KEGG and PIUmet analyses and key enzymes were detected by Western blot. Hepatosteatosis models of HepG2 cells and primary hepatocytes were used to further confirm the therapeutic effect of GLPP on NAFLD.

Results: GLPP administrated for a month alleviated hepatosteatosis, dyslipidemia, liver dysfunction and liver insulin resistance. Pathways of glycerophospholipid metabolism, fatty acid metabolism and primary bile acid biosynthesis were involved in the therapeutic effect of GLPP on NAFLD. Detection of key enzymes revealed that GLPP reversed low expression of CYP7A1, CYP8B1, FXR, SHP and high expression of FGFR4 in ob/ob mice and ApoC3 mice. Besides, GLPP inhibited fatty acid synthesis by reducing the expression of SREBP1c, FAS and ACC via a FXR-SHP dependent mechanism. Additionally, GLPP reduced the accumulation of lipid droplets and the content of TG in HepG2 cells and primary hepatocytes induced by oleic acid and palmitic acid.

Conclusion: GLPP significantly improves NAFLD via regulating bile acid synthesis dependent on FXR-SHP/FGF pathway, which finally inhibits fatty acid synthesis, indicating that GLPP might be developed as a therapeutic drug for NAFLD."[21]



references

  1. GRCh38: Ensembl release 89: ENSG00000012504 - Ensembl, May 2017

  2. ^ Jump up to:a b c GRCm38: Ensembl release 89: ENSMUSG00000047638 - Ensembl, May 2017

  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

  5. ^ "Entrez Gene: NR1H4 nuclear receptor subfamily 1, group H, member 4".

  6. ^ Jump up to:a b Forman BM, Goode E, Chen J, Oro AE, Bradley DJ, Perlmann T, Noonan DJ, Burka LT, McMorris T, Lamph WW, Evans RM, Weinberger C (Jun 1995). "Identification of a nuclear receptor that is activated by farnesol metabolites". Cell. 81 (5): 687–93. doi:10.1016/0092-8674(95)90530-8. PMID 7774010.

  7. ^ Yang F, Huang X, Yi T, Yen Y, Moore DD, Huang W. Spontaneous development of liver tumors in the absence of the bile acid receptor farnesoid X receptor. Cancer Res. 2007 Feb 1;67(3):863-7. doi: 10.1158/0008-5472.CAN-06-1078. PMID: 17283114

  8. ^ Jump up to:a b c Jiao Y, Lu Y, Li XY (Jan 2015). "Farnesoid X receptor: a master regulator of hepatic triglyceride and glucose homeostasis". Acta Pharmacologica Sinica. 36 (1): 44–50. doi:10.1038/aps.2014.116. PMC 4571315. PMID 25500875.

  9. ^ Mroz MS, Keating N, Ward JB, Sarker R, Amu S, Aviello G, Donowitz M, Fallon PG, Keely SJ (May 2014). "Farnesoid X receptor agonists attenuate colonic epithelial secretory function and prevent experimental diarrhoea in vivo". Gut. 63 (5): 808–17. doi:10.1136/gutjnl-2013-305088. PMID 23916961. S2CID 15778582.

  10. ^ Zhang Y, Castellani LW, Sinal CJ, Gonzalez FJ, Edwards PA (Jan 2004). "Peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha) regulates triglyceride metabolism by activation of the nuclear receptor FXR". Genes & Development. 18 (2): 157–69. doi:10.1101/gad.1138104. PMC 324422. PMID 14729567.

  11. ^ Seol W, Choi HS, Moore DD (Jan 1995). "Isolation of proteins that interact specifically with the retinoid X receptor: two novel orphan receptors". Molecular Endocrinology. 9 (1): 72–85. doi:10.1210/mend.9.1.7760852. PMID 7760852.

  12. ^ Fiorucci S, Zampella A, Distrutti E (2012). "Development of FXR, PXR and CAR agonists and antagonists for treatment of liver disorders". Current Topics in Medicinal Chemistry. 12 (6): 605–24. doi:10.2174/156802612799436678. PMID 22242859.

  13. ^ Fiorucci S, Mencarelli A, Distrutti E, Zampella A (May 2012). "Farnesoid X receptor: from medicinal chemistry to clinical applications". Future Medicinal Chemistry. 4 (7): 877–91. doi:10.4155/fmc.12.41. PMID 22571613.

  14. ^ Vaz B, de Lera ÁR (Nov 2012). "Advances in drug design with RXR modulators". Expert Opinion on Drug Discovery. 7 (11): 1003–16. doi:10.1517/17460441.2012.722992. PMID 22954251. S2CID 36317393.

  15. ^ Ricketts ML, Boekschoten MV, Kreeft AJ, Hooiveld GJ, Moen CJ, Müller M, Frants RR, Kasanmoentalib S, Post SM, Princen HM, Porter JG, Katan MB, Hofker MH, Moore DD (Jul 2007). "The cholesterol-raising factor from coffee beans, cafestol, as an agonist ligand for the farnesoid and pregnane X receptors". Molecular Endocrinology. 21 (7): 1603–16. doi:10.1210/me.2007-0133. PMID 17456796.

  16. ^ Zhang, S.; Pan, X.; Jeong, H. (2015). "GW4064, an Agonist of Farnesoid X Receptor, Represses CYP3A4 Expression in Human Hepatocytes by Inducing Small Heterodimer Partner Expression". Drug Metabolism and Disposition. 43 (5): 743–748. doi:10.1124/dmd.114.062836. PMC 4407707. PMID 25725071.

  17. ^ Carotti A, Marinozzi M, Custodi C, Cerra B, Pellicciari R, Gioiello A, Macchiarulo A (2014). "Beyond bile acids: targeting Farnesoid X Receptor (FXR) with natural and synthetic ligands". Current Topics in Medicinal Chemistry. 14 (19): 2129–42. doi:10.2174/1568026614666141112094058. PMID 25388537. Archived from the original on 2021-10-19.

  18. ^ Jin L, Feng X, Rong H, Pan Z, Inaba Y, Qiu L, et al. (2013). "The antiparasitic drug ivermectin is a novel FXR ligand that regulates metabolism". Nature Communications. 4: 1937. Bibcode:2013NatCo...4.1937J. doi:10.1038/ncomms2924. PMID 23728580.

  19. Farnesoid X Receptor Induces GLUT4 Expression Through FXR Response Element in the GLUT4 Promoter. Hong Shen; et. al. Cellular Physiology and Biochemistry (2008) 22 (1-4): 001–014. https://doi.org/10.1159/000149779. RESEARCH ARTICLES| JULY 25 2008

  20. The bile acid sensor FXR regulates insulin transcription and secretion. Barbara Renga a, Andrea Mencarelli a, et. al. https://doi.org/10.1016/j.bbadis.2010.01.002. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease. Volume 1802, Issue 3, March 2010, Pages 363-372

  21. Ganoderma Lucidum Polysaccharide Peptide Alleviates Hepatoteatosis via Modulating Bile Acid Metabolism Dependent on FXR-SHP/FGF. Dandan Zhong 1, Zhengwei Xie, et. al. Cell Physiol Biochem. . 2018;49(3):1163-1179. doi: 10.1159/000493297. Epub 2018 Sep 7. PMID: 30196282. DOI: 10.1159/000493297

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