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At least 19 recordsLinked to original sources
PubMed2025

Role of oxysterol 4β-hydroxycholesterol and liver X receptor alleles in pre-eclampsia.

BACKGROUND: Liver X receptors (LXRs) are expressed in placenta and may be associated with pre-eclampsia (PE). Oxysterols act as agonists for LXRs. We recently proposed a new blood pressure-regulating circuit with oxysterol 4β-hydroxycholesterol (4βHC) acting as a hypotensive factor via LXRs. MATERIALS AND METHODS: This study investigated the association between maternal plasma 4βHC, blood pressure (BP) indices, placental expression of LXR target genes, and patient characteristics using data from the Finnish Genetics of Pre-Eclampsia Consortium (FINNPEC) cohort. Plasma samples of 144 women with PE and 38 healthy pregnant controls as well as 44 PE and 40 control placental samples were available. In addition, genetic data from the FinnGen project was utilized to explore the associations of LXR alleles with PE and pregnancy hypertension. RESULTS: There were no significant associations between 4βHC and BP or maternal and perinatal characteristics in FINNPEC cohort. However, plasma 4βHC was inversely correlated with the maternal body mass index. There were no associations with the genetic variants of LXRs with PE in FinnGen. LXR target genes APOD, SCARB1, TGM2, and LPCAT3 were expressed differently between PE and normal pregnancies in placental samples of FINNPEC. CONCLUSIONS: Our results demonstrate that plasma 4βHC and genetic LXR variants do not play a major role in PE and BP regulation during pregnancy. However, key LXR target genes involved in lipid metabolism were expressed differently in normal and PE pregnancies. Further research is needed to understand the complexities of oxysterols, LXRs, and their potential contributions to placental function and pregnancy outcomes.

Humans↗
PubMed2026

Machine Learning in Hyperlipidaemia Research: Screening and Experimental Insights into Lipid Metabolism Modulators.

Hyperlipidemia, characterized by elevated blood lipid levels, represents a major global health concern due to its strong association with cardiovascular disease, diabetes, and metabolic syndrome. While current therapies - such as statins, fibrates, bile acid sequestrants, and PCSK9 inhibitors - are effective in controlling hyperlipidemia, they are often associated with adverse effects, potential drug resistance, and suboptimal efficacy in certain patient populations. All of the above underscore the urgent need for safer and more effective therapeutic alternatives. Among the major molecular targets involved in the regulation of lipid metabolism are HMG-CoA reductase, PCSK9, peroxisome proliferator-activated receptors (PPARs), cholesteryl ester transfer protein (CETP), and nuclear receptors, including the liver X receptor (LXR) and farnesoid X receptor (FXR), which are also targets for future antihyperlipidemic drug development. Recent advancements in artificial intelligence (AI) and machine learning (ML) have significantly transformed and accelerated drug discovery by enabling the processing of vast amounts of genomic, proteomic, and chemical data. Furthermore, ML tools such as quantitative structure-activity relationship (QSAR) modelling, deep learning, random forest, and support vector machines (SVM) have proven predictive and effective in identifying novel lipid metabolism modulators, thereby enhancing the efficacy and accuracy of virtual screening. Meanwhile, molecular docking has become an integral part of structure-based drug design (SBDD), and software such as AutoDock, Glide, and GOLD have proven effective in generating accurate ligand-target docking models. Molecular docking, together with ML-based approaches, enables the identification of potent and selective drug candidates. Overall, the combination of ML and molecular docking offers an efficient and accurate platform for antihyperlipidemic drug discovery, helping to overcome the limitations of currently available therapeutic strategies.

HMG-CoA reductase↗
PubMed2026

The phytosterol 24(S)-saringosterol alters lipid homeostasis and inflammatory pathways in a cell-specific manner.

BACKGROUND: Neuroinflammation and disrupted cholesterol metabolism in microglia are key contributors to Alzheimer's disease (AD) pathogenesis. Liver X receptors (LXRα/β) regulate lipid metabolism and inflammation. Synthetic pan-LXR agonists, such as T0901317 and GW3965, exert neuroprotective effects by modulating lipid metabolism, making them promising therapeutic strategies for neurodegenerative disorders like Alzheimer's Disease (AD). However, their clinical use is limited by hepatic side effects, including hypertriglyceridemia and steatosis. PURPOSE: To overcome these limitations, we investigated 24(S)-saringosterol, a phytosterol from Sargassum fusiforme, and its potential dissociating effect as a LXR agonist on myeloid cells vs hepatocytes. METHOD: Using primary cultures of myeloid cells (microglia, bone marrow-derived macrophages) and hepatocytes, we performed transcriptomic and lipidomic analyses to assess the impact of 24(S)-saringosterol on lipid metabolism and inflammatory pathways. RESULTS: 24(S)-saringosterol strongly activated LXR-regulated genes, upregulating cholesterol efflux transporter Abca1 in a dose-dependent manner. In myeloid cells, it reduced the expression of interferon-β pathway genes and promoted cholesterol efflux, mirroring GW3965's anti-inflammatory effects. Notably, 24(S)-saringosterol downregulated cholesterol biosynthesis (Dhcr24) and influx (Ldlr) via Srebp2 in both cell types, contrasting with GW3965, which increased lipid synthesis genes via Srebp1. CONCLUSION: These findings suggest 24(S)-saringosterol acts as a selective LXR agonist in a cell-specific manner, retaining beneficial effects while minimizing hepatic risks. This compound represents a promising candidate for AD and other metabolic or inflammatory disorders.

Animals↗
PubMed2026

Functional perturbation reveals context-dependent contributions of nuclear receptors to drug-induced hepatic steatosis.

Drug-induced hepatic steatosis is mediated by diverse molecular mechanisms, yet several nuclear receptors have been proposed as molecular initiating events or early key events within adverse outcome pathways for hepatic steatosis. However, direct functional evidence supporting these mechanistic roles in human-relevant experimental systems remains limited. The present study evaluated the contribution of selected nuclear receptors to drug-induced hepatic steatosis using complementary human hepatic in vitro models. Stable short hairpin RNA-mediated knockdown of individual nuclear receptors was established in HepG2 and differentiated HepaRG cells, followed by exposure to representative steatogenic drugs, including valproic acid, amiodarone, tamoxifen, and rifampicin. In parallel, primary human hepatocyte spheroids were used to compare drug-induced lipid accumulation with direct pharmacological activation of individual nuclear receptor pathways. While depletion of multiple nuclear receptors markedly affected oleic acid-induced lipid accumulation, drug-induced steatogenic responses exhibited predominantly selective and compound-specific receptor dependencies. In differentiated HepaRG cells, nuclear receptor depletion influenced basal lipid homeostasis more strongly than valproic acid-induced lipid accumulation. Conversely, direct activation of liver X receptor and peroxisome proliferator-activated receptors α and γ in primary human hepatocyte spheroids induced robust lipid accumulation, whereas most steatogenic drugs produced comparatively modest responses. These findings demonstrate that the contribution of individual nuclear receptors to drug-induced hepatic steatosis is highly compound- and context-dependent and cannot be explained by a single conserved receptor pathway. This study provides functional evidence from complementary human-relevant hepatic models that supports refinement of hepatic steatosis adverse outcome pathways and highlights the value of targeted perturbation strategies for mechanistic toxicology.

Adverse outcome pathway, HepaRG↗
PubMed2025

Mitochondrial dysfunction fuels drug resistance in adult T-cell acute lymphoblastic leukemia.

BACKGROUND: T-cell acute lymphoblastic leukemia (T-ALL) is a relatively rare hematological malignancy, characterized by the uncontrolled proliferation of immature T lymphoblasts and associated with a generally unfavorable prognosis. Our previous research has demonstrated that decreased mitochondrial activity is associated with the aggressiveness of T-ALL tumors. However, the mechanisms underlying this phenomenon and its contribution to treatment resistance remain largely elusive. METHODS: We have built up the largest known T-ALL tumor bank, with a median follow-up of 32 months, including our transcriptomic data from 79 newly sequenced tumors that adds to the 54 publicly accessible samples. Computational analyses and a series of functional assays were performed to investigate the molecular links between altered mitochondrial activity and drug resistance. RESULTS: The transcriptomic analysis revealed that down-regulation of mitochondrial activity is a potent driver of ABCB1 activation, a gene strongly associated with multidrug resistance. In tumors with low mitochondrial activity, the impaired fatty acids β-oxidation leads to intracellular lipid accumulation, which is directly involved in ABCB1 activation. Indeed, our data show that lipid neo-synthesis and accumulation promotes the activation of lipogenic transcription factors, liver X receptors (LXRs), which act as drivers of ABCB1 expression. Tumor data analyses confirmed that high ABCB1 expression in tumour samples is indeed associated with reduced mitochondrial gene expression, lipid droplet enrichment, increased tumour aggressiveness, and significantly shorter patient survival. CONCLUSIONS: Our study demonstrates that reduced mitochondrial activity drives multidrug resistance in adult T-ALL via lipid-mediated activation of ABCB1. These findings enhance our understanding of the biology of aggressive T-ALL and provide insight into mechanisms of resistance to conventional chemotherapy. Consequently, we propose that targeting de novo lipogenesis and restricting dietary fats, such as caprylic acid, may help overcome treatment resistance in patients with T-ALL exhibiting low mitochondrial activity. TRIAL REGISTRATION: The clinical trial was registered under the identifiers ChiCTR-ONRC-14004968 and ChiCTR2000031553 at ClinicalTrials.gov.

Adult↗
PubMed2025

Beta-catenin/sirtuin 1/farnesoid X receptor pathway promotion of portal vein ligation and parenchymal transection-induced rapid liver regeneration.

BACKGROUND: By accelerating the regeneration of the future liver remnant, portal vein ligation and parenchymal transection allows for more extensive hepatectomy. Given that the mechanism remains poorly understood, the aim of this study was to investigate the mechanism of portal vein ligation and parenchymal transection-induced liver regeneration. METHODS: A portal vein ligation and parenchymal transection-induced liver regeneration mouse model was established, followed by RNA microarray analysis to identify candidate molecules. Genomic deletion and chemical manipulation of target molecules were used to explore their functions in portal vein ligation and parenchymal transection-induced liver regeneration. Validation was conducted using a diseased liver model and human samples. RESULTS: Portal vein ligation and parenchymal transection-induced liver regeneration was significantly accelerated compared with that in sham-operated mice (P < .05). An RNA microarray revealed that Sirtuin 1 is a crucial molecule in the proliferation of the future liver remnant. Regardless of whether Sirtuin 1 is inhibited chemically or through genetic deletion, portal vein ligation and parenchymal transection-induced liver regeneration is distinctly attenuated. Further investigation revealed that Sirtuin 1 promoted portal vein ligation and parenchymal transection-induced liver regeneration via the farnesoid X receptor. In addition, beta-catenin also was found to participate in the process of future liver remnant proliferation. Chemical inhibition of beta-catenin markedly impaired but activation of WNT/beta-catenin mildly enhanced portal vein ligation and parenchymal transection-induced liver regeneration (P < .05). Deletion of Sirtuin 1 blocked the facilitating effect of beta-catenin on portal vein ligation and parenchymal transection-induced liver regeneration. These findings were validated in diseased liver models and patient samples, confirming the correlation between the beta-catenin/Sirtuin 1/farnesoid X receptor pathway and portal vein ligation and parenchymal transection-induced liver regeneration. CONCLUSION: Activation of the beta-catenin/Sirtuin 1/farnesoid X receptor pathway offers critical mechanistic insights into accelerating portal vein ligation and parenchymal transection-induced liver regeneration. Modulation of beta-catenin/Sirtuin 1/farnesoid X receptor may therefore improve clinical outcomes in patients receiving staged hepatectomy.

Liver Regeneration↗
PubMed2026

Proteomics Analysis of Plasma for Risk of Sepsis: Findings from the Atherosclerosis Risk in Communities Study.

BACKGROUND: Sepsis is a life-threatening complication of infection with high mortality. A high-throughput analysis of circulating blood proteins may provide mechanistic insight and potent therapeutic targets for the prevention of sepsis. METHODS: We used multivariable Cox regression analysis to examine the association of 4955 plasma proteins, measured by SomaScan, with the risk of incident sepsis among 11 065 participants of the Atherosclerosis Risk in Communities (ARIC) Study (visit 3 in 1993 to 1995; mean age, 60.1 years, 54.4% female, 21.0% Black). Proteins (false discovery rate [FDR] of P < 0.05) discovered at visit 3 were replicated using data at visit 5 (n = 4869 in 2011 to 2013: mean age, 75.5 years) and in the Cardiovascular Health Study (CHS) (n = 3512 in 1992 to 1993; mean age, 74.5 years). Canonical pathways were identified by enrichment analyses. RESULTS: At ARIC visit three, 669 proteins were associated with the risk of sepsis; 175 were replicated at visit 5. Of these, 90 were validated in the CHS. The top 20 proteins ranked by P value were relevant to acute inflammatory signaling in innate immunity. Pathway analyses implicated activation of pro-inflammatory pathways (e.g., cytokine storm signaling) as well as inhibition of anti-inflammatory pathways (e.g., liver X receptor/retinoid X receptor [LXR/RXR] activation), which also play relevant roles in lipid metabolism. CONCLUSIONS: In this analysis, levels of acute inflammatory proteins measured during routine visits were associated with the subsequent incidence of sepsis. An increased risk of sepsis associated with the inhibition of anti-inflammatory pathways, such as LXR/RXR warrants further mechanistic investigation.

Humans↗
PubMed2025

Deletion of hepatic FXR leads to more severe MASH development in female mice.

BACKGROUND: The farnesoid X receptor (FXR) has been identified as a therapeutic target for metabolic dysfunction-associated steatohepatitis (MASH). FXR is the major homeostatic regulator of bile acids (BAs) with dysregulation of BAs and/or FXR implicated in the pathogenesis of MASH. Synthetic whole-body FXR agonists have been developed to treat MASH. Although beneficial for MASH treatment, these whole-body modulators contribute to unfavorable side effects such as pruritus and an elevation in low-density liporoteins, thereby highlighting the importance of tissue and cell-restricted modulation of FXR in the development of novel therapeutics for MASH to negate potential harmful off-target effects. METHODS: The objective of this study was to determine the tissue-specific role of FXR in MASH development using male and female wild-type (WT), liver FXR KO (FXRhep-/-), intestinal FXR KO (FXRint-/-), and whole body FXR KO (FXR KO) mice fed either a low-fat control diet (CTL) or a MASH "Fast Food" (FF) diet. RESULTS: The results showed, in females, hepatic, but not intestinal, deficiency of FXR was associated with severe liver injury, through increased ALT, ALP, and genes indicative of inflammation and fibrosis when comparing FXRhep-/- versus FXRint-/-. Regardless of sex, hepatic FXR deficiency triggered the activation of neuroinflammation and neurodegenerative canonical pathways. CONCLUSIONS: These data suggest that hepatic FXR is more critical in suppressing liver injury during MASH development in female mice. However, this same trend was not clear in the male cohorts, highlighting sex differences and potential roles for sexual dimorphism in MASH development.

Animals↗
PubMed2025

Changes in the FXR-cistrome and alterations in bile acid physiology in Wilson disease.

BACKGROUND: Wilson disease (WD) is an autosomal recessive disorder that results in excessive hepatic copper, causing hepatic steatosis, inflammation, fibrosis, cirrhosis, and liver failure. Previous studies have revealed dysregulation of many farnesoid X receptor (FXR) metabolic target genes in WD, including the bile salt exporter pump, the major determinant of bile flow. METHODS: We tested the hypothesis that the FXR-cistrome is decreased in Atp7b-/- mice in accord with dysregulated bile acid homeostasis. RESULTS: FXR binding within Atp7b-/- mouse livers displayed surprising complexity: FXR binding was increased in distal intergenic regions but decreased in promoter regions in Atp7b-/- versus wild-type mice. Decreased FXR occupancy in Atp7b-/- versus wild-type mice was observed in hepatocyte metabolic and bile acid homeostasis pathways, while enrichment of FXR binding was observed in pathways associated with cellular damage outside of hepatocytes. Indeed, disparate FXR occupancy was identified in parenchymal and non-parenchymal marker genes in a manner that suggests decreased FXR activity in parenchymal cells, as expected, and increased FXR activity in non-parenchymal cells. Consistent with altered FXR function, serum and liver bile acid concentrations were higher in Atp7b-/- mice than in wild-type mice. Comparison of bile acid profiles in the serum of WD patients with "liver," "neurological," or "mixed" disease versus healthy controls also revealed increases in specific bile acids in WD-liver versus healthy controls. CONCLUSIONS: We identified novel FXR-occupancy across the genome that varied in parenchymal and non-parenchymal cells, demonstrating complex FXR regulation of metabolic and hepatocellular stress pathways in Atp7b-/- mice. Dynamic changes in FXR activity support our novel finding of altered bile acid metabolism in Atp7b-/- mice and WD patients.

Animals↗
PubMed1978

Insulin receptors in AH-66 ascites hepatoma cells and liver of tumor-bearing rats.

Properties of insulin receptor on plasma membranes isolated from AH-66 ascites hepatoma cells and liver of tumor-bearing rats were studied. Specific binding (total binding minus nonspecific binding) of 125-I-labeled insulin to plasma membranes from AH-66 tumor cells and liver of normal and tumor-bearing rats were 33, 31, and 16% of a fixed amount of labeled insulin (1 x 10(5) cpm) added to each membrane preparation, respectively. Using Nisonoff plot, these membranes were found to possess at least two types of insulin receptors with a high affinity-low capacity and a low affinity-high capacity, as has been shown in normal liver. Total number of binding sites (high affinity plus low affinity sites, 8.4 x 10(-12) mol/mg protein) in hepatoma cells was more than that (7.0 x 10(-12) mol/mg protein) in normal rat liver. However, kinetic constants of binding in receptors of two types on tumor cells and tumor-bearing rat liver were similar to those of membrane receptors from normal rat liver. Insulin receptors of the hepatoma cells were considered to be highly specific for insulin from the results of competition with other peptide hormones. Inhibition of insulin binding with the tumor cell membranes by concanavalin-A, a competitive inhibitor for insulin receptor sites, did not differ very greatly from that of normal liver.

Adrenocorticotropic Hormone↗
PubMed1976

[Comparative characteristics of cytosol glucocorticoid receptors from normal liver, the liver of tumor-bearing rats and hormone unresponsive Zajdela hepatoma].

Specific dexametasone (D) and cortisol (F) receptors have been found both in liver and Zajdela hepatoma. Rat liver cytosol receptors are characterized by the association constant (Kas) = 3,8 X 10(8) M-1 for D and 0,57 X 10(8) M-1 for F as well as by a number of binding sites (NBS)=4,9 X 10(-13) moles/mg protein and 4,06 X 10(-13) moles/mg protein, respectively. The receptors show stric specificity to glucocorticoids. Cytosol glucocorticoid-receptor complexes from liver and hepatoma sediment at 6-7S, when centrifuged in the buffer of a low ionic strength, and at 3-4S in the buffer of a high ionic strength (0,4 M KCl). The properties of cytosol receptors in the course of in vivo hepatoma growth were found to be gradually altering: Kas for D dropped whereas that for F increased; the NBS is decreased 3-4 fold as compared to normal liver cytosol--which may partially be accounted for by the unresponsiveness of the tumour to the hormones.

Animals↗
PubMed1976

Specific binding of human and bovine growth hormones to hypophysectomized rat hepatocytes.

Specific binding of 125I-HGH and 125I-bGH was obtained in hypophysectomized rat liver cells. Two types of somatogenic receptors were found with apparent dissociation constants of 4.2 x 10(8) M-1 and 1.7 x 10(7) M-1. The number of sites for the higher and lower affinity receptors were: 1 x 10(4) and 6 x 10(3), respectively. Human, bovine and equine growth hormones appear to bind to liver cells with equal affinity, while ovine prolactin needs at least a two-order-magnitude greater concentration to displace 125I-bGH. A parallelism between biological activity and binding data was observed.

Animals↗
PubMed1978

Hepatic alpha-adrenergic receptors. Identification and subcellular localization using [3H]dihydroergocryptine.

Recently, several workers have shown that adrenergic control of hepatic carbohydrate metabolism has the characteristics of an alpha-receptor-mediated process. Using the rat liver membrane preparation of Neville (Neville, D. (1968) Biochim. Biophys. Acta 154, 540-552), alpha-adrenergic receptors have been identified using the ligand [3H]dihydroergocryptine. The receptors are saturable and of high affinity. Scatchard analysis yields a KD of 1.8 nM with 1.7 +/- 0.55 pmol of sites/mg of protein. Competition of dihydroergocryptine binding with various pharmacologic agents yields the typical (alpha-adrenergic potency series: (-)-epinephrine greater than (-)-norepinephrine greater than (-)-isoproterenol. (-)-Isomers are more potent than (+)-isomers. The alpha-blocker phentolamine is 3.4 orders of magnitude more potent than the beta-blocker propranolol. To determine subcellular localization of alpha-adrenergic receptors, livers were fractionated into a crude homogenate, a 1500 X g pellet, and the purified membrane preparation used previously for binding. Specific dihydroergocryptine binding, ouabain-inhibitable (Na,K)-ATPase, and F--stimulated adenylate cyclase activities, were followed in these fractions. Specific binding was enriched, relative to that in the crude homogenate, 2.88-fold in the pellet and 6.28-fold in the membranes. Similarly, (Na,K)-ATPase acticity was enriched 2.6-fold in the pellet and 7.1-fold in the membranes while adenylate cyclase activity was enriched 2.9-fold in the pellet and 3.5-fold in the membranes. It is concluded that hepatic alpha-adrenergic receptors are likely concentrated in the plasma membranes.

Adenylyl Cyclases↗
PubMed1979

The insulin receptor of embryonic chicken cartilage.

Highly purified plasma membranes have been obtained from embryonic chicken cartilage by physical means rather than enzymatic digestion. Rapid and reversible binding of [125I]iodoinsulin to these membranes is demonstrated. Similar to the insulin-binding properties of rat liver and adipocytes and human mononuclear cells, optimal specific binding of insulin to chondrocyte plasma membranes has a sharp pH optimum at 8.0, and maximal binding occurs at 2--4 C. Analysis of equilibrium binding reveals a curvilinear Scatchard plot, whose high affinity segment generates a maximum affinity of 1.0 X 10(9) M-1, and a receptor concentration of 0.4 pmol/mg membrane protein. This affinity constant is similar to those generated for insulin binding to membranes prepared from embryonic chicken liver (2.5 X 10(9) M-1), rat liver (1.4 X 10(9) M-1), and mouse liver (0.6 X 10(9) M-1), whereas the receptor concentration is less than that of embryonic chicken liver membranes (1.1 pmol/mg), which in turn was less than those of rat liver membranes (2.8 pmol/mg) and mouse liver membranes (3.5 pmol/mg). Kinetic studies show augmentation of insulin-receptor dissociation by excess insulin when initial receptor occupancy, is low, suggesting that negative cooperativity is present. There is little or no interaction of other hormones with the chondrocyte insulin receptor, with the exception of proinsulin and the insulin-like growth factors. Porcine proinsulin, bovine proinsulin, somatomedin C, and nonsuppressible insulin-like protein prevent [125I]iodoinsulin binding to chondrocyte plasma membranes with dose-response curves which are parallel to that of unlabeled porcine insulin itself, but with molar potencies relative to porcine insulin of 15%, 9%, 2.5%, and 1.4%, respectively. Porcine insulin and proinsulin both prevent binding of [125I]iodosomatomedin C to chondrocyte plasma membranes but with molar potencies less than 1% that of unlabeled somatomedin C. These observations are consistent with the presence of a specific independent insulin receptor in embryonic chicken cartilage which is similar in its characteristics to the insulin receptor in previously described tissues. Insulin has a weak interaction with the chondrocyte receptor for somatomedin C. Interaction with the somatomedin receptor may be the mechanism by which insulin exerts anabolic effects on cartilage when used in pharmacological amounts.

Animals↗
PubMed1979

Studies on the nuclear binding of steroid hormone-receptor complex; characteristics of binding of nuclei from fetal rat liver to 3H-dexamethasone-liver cytoplasmic receptor complex.

Binding of 3H-dexamethasone (Dex)-rat liver cytoplasmic receptor complex to nuclei from fetal rat livers in vitro exhibited a high-affinity and saturable nature (Kd=1.5 X 10- M, maximal binding sites=470 fmole/mg DNA), and the binding was inhibited competitively by prior injection of Dex in vivo. While binding of 3H-Dex-receptor complex to nuclei from adult rat liver was in low affinity and unsaturable, and injection of Dex prior to the sacrifice of animals did not influence the nuclear binding to 3H-Dex-receptor complex in vitro. Differential salt-extraction with KCl solution of the nuclear bound 3H-Dex receptor complex revealed the presence of salt-extractable and residual forms of bound receptors. The amount of the fraction extracted with 0.3 M KCl reached its maximum at 10 min after the start of incubation, while the 1.0 M KCl-extractable and residual fractions reached their maximum plateaus after 30 min of the incubation. Scatchard analysis revealed that the binding of the receptor complex to the 0.3M and 1.0M KCl fractions was saturable, while the residual fraction did not show any tendency of saturation under the experimental conditions employed in the present study. The results obtained in this work were compared to those which have been reported by other investigators.

Animals↗
PubMed1975

Estrogen receptor in rat liver and its dependence on prolactin.

Estrogen receptor is shown to be present in the livers of adult rats. The receptor binds estradiol-17beta with a Kd of 1 x 10(-10) M and sediments at 8 S in sucrose gradients. Other estrogens and anti-estrogens compete for estradiol binding, while nonestrogenic steroids do not. Receptor levels fall dramatically after hypophysectomy, but can be partially restored within 18 hours by a single injection of prolactin. It is known that prolactin critically regulates the level of its own receptor in the liver, and we now suggest that it also exerts a primary control over the availability of liver estrogen receptor.

Animals↗
PubMed1979

Isolation and partial characterization of a water-soluble receptor protein of insulin.

By using the chelate EDTA at low concentration to remove the bivalent cations in the plasma membranes and followed by n-butanol to extract the membrane lipids, we have obtained a water-soluble insulin receptor without detergent from the liver-cell plasma membranes. This receptor protein does not precipitate by centrifugation at 300,000 X g for 70 min, nor does it retain on 0.22 micron millipore filter. It does not retard on Sephadex G-200 gel chromatographic column either. It is thus proved that the insulin-receptor protein obtained by this method is completely soluble in water. The dissociation constant of the water-soluble receptor of insulin at 24 degrees C is calculated to be 3.6 X 10(-9) M and its isoelectric point was approximately pH 4.1. As the fluorescence hydrophobic probe 1,8-ANS does not significantly affect the binding activity between the receptor and the insulin, it seems that in addition to a hydrophobic binding mechanism, there may exist some other forces of interaction.

Animals↗
PubMed1978

Glucocorticoid receptors in the guinea pig.

In cytoplasmic fractions of liver and kidney prepared from adrenalectomized guinea pigs, tritiated dexamethasone ([3H]DM) is bound with a very low affinity (Kd 4 degrees C greater than or equal to 2 X 10(-7) M). By competition studies, the specificity of this binding was shown to be comparable with that for [3H]DM binding to glucocorticoid receptors in other species. In addition, cytoplasmic preparations from guinea pig liver and kidney appear to inhibit the binding of [3H]DM to rat glucocorticoid receptors under a variety of experimentally determined circumstances. It is proposed that such inhibitory activity may reflect a system of [3H]DM sequestration, perhaps by metabolizing enzymes with a high combining power for glucocorticoids. Both low affinity glucocorticoid receptors and avid binding to sites of metabolism may represent additive cellular bases for the apparent corticoresistance of the guinea pig.

Adrenal Cortex Hormones↗