Interactions Between Nuclear Receptor SHP and FOXA1 Maintain Oscillatory Homocysteine Homeostasis in Mice

Abstract

BACKGROUND & AIMS Hyperhomocysteinemia is often associated with liver and metabolic diseases. We studied nuclear receptors that mediate oscillatory control of homocysteine homeostasis in mice. METHODS We studied mice with disruptions in Nr0b2 (called SHP-null mice) Bhmt, or both genes (BHMT-null/SHP-null mice), along with mice with wild-type copies of these genes (controls). Hyperhomocysteinemia was induced by feeding mice alcohol (the NIAAA binge model) or chow diets along with water containing 0.18% DL-homocysteine. Some mice were placed on diets containing cholic acid (1%) or cholestyramine (2%), or high-fat diets (60%). Serum and livers were collected over a 24 hr light–dark cycle and analyzed by RNA-seq, metabolomic, and quantitative PCR, immunoblot, and chromatin immunoprecipitation assays. RESULTS SHP-null mice had altered timing in expression of genes that regulate homocysteine metabolism, compared with control mice. Oscillatory production of S-adenosylmethionine, betaine, choline, phosphocholine, glyceophosphocholine, cystathionine, cysteine, hydrogen sulfide, glutathione disulfide, and glutathione, differed between SHP-null mice and control mice. SHP inhibited transcriptional activation of Bhmt and Cth by FOXA1. Expression of Bhmt and Cth was decreased when mice were fed cholic acid but increased when they were placed on diets containing cholestyramine or high-fat content. Diets containing ethanol or homocysteine induced hyperhomocysteinemia and glucose intolerance in control but not SHP-null mice. In BHMT-null and BHMT-null/SHP-null mice fed a control liquid, lipid vacuoles were observed in livers. Ethanol feeding induced accumulation of macrovesicular lipid vacuoles to the greatest extent in BHMT-null and BHMT-null/SHP-null mice. CONCLUSIONS Disruption of Shp in mice alters timing of expression of genes that regulate homocysteine metabolism and the liver responses to ethanol and homocysteine. SHP inhibits the transcriptional activation of Bhmt and Cth by FOXA1.

Pyruvate Dehydrogenase Kinase 4 Deficiency Results in Expedited Cellular Proliferation through E2F1-Mediated Increase of Cyclins

“…Western blotting and quantitative polymerase chain reaction (qPCR) methods were well established in our laboratory, as described previously (Yang et al, 2013b;Tsuchiya et al, 2015). All antibodies used for Western blotting were as follows: cyclin D1 (Cell Signaling Technology), cyclin E1 (Cell Signaling Technology), cyclin A2 (Cell Signaling Technology), cyclin D3 (Cell Signaling Technology), cyclin H (Cell Signaling Technology), cyclin E2 (Cell Signaling Technology), CDK2 (Santa Cruz Biotechnology, Dallas, TX), CDK4 (Santa Cruz Biotechnology), b-actin (Cell Signaling Technology), glyceraldehyde 3-phosphate dehydrogenase (Cell Signaling Technology), p21 (Santa Cruz Biotechnology), Rb (Santa Cruz Biotechnology), pRB (Cell Signaling Technology), MyB (Millipore, Billerica, MA), glycogen synthase kinase-3b (Abcam, Cambridge, UK), SMAD4 (Thermo Fisher Scientific, Waltham, MA), and E2F1 (Thermo Fisher Scientific).…”

Nuclear receptors and liver disease: Summary of the 2017 basic research symposium

“…SHP has been shown to be involved in BA synthesis, lipid and cholesterol metabolism, glucose homeostasis, apoptosis, and cell invasion 36, 37, 38, 39, 40, 41, 42, 43. SHP has also been identified as a mediating factor in the metabolic circadian clock 44, 45, 46, 47, 48. In addition, SHP acts as a transcriptional repressor of microRNA expression and function through interaction with other nuclear receptors 49, 50, 51, 52.…”

Nuclear Receptors as Therapeutic Targets in Liver Disease: Are We There Yet?

“…However, SHP-null were resistant to HFD-induced fatty liver and obesity (15, 20, 38), which is mediated by the liver Clock and Npas2 genes (39, 40). Interestingly, alcohol-induced macrovesicular lipid vacuoles were diminished in SHP-null mice that were associated with the decreased hyperhomocysteinemia (41). Finally, human fibroblast growth factor 19 (FGF19) is an enterohepatic hormone that is involved in the regulation of hepatic metabolism of BAs, lipids, and glucose.…”