Individual susceptibility to alcohol-related liver disease (ALD) varies substantially despite similar alcohol consumption patterns. Emerging evidence suggests metabolism-disrupting agents (MDAs) may synergistically amplify alcohol-induced hepatotoxicity, yet population-level evidence remains limited. This study investigated associations between 40 MDAs and ALD risk using integrated analytical approaches. We analyzed 13,472 National Health and Nutrition Examination Survey participants (2005–2016). Forty MDAs spanning per- and polyfluoroalkyl substances, phenolic compounds, phthalate metabolites, polycyclic aromatic hydrocarbon metabolites, and volatile organic compound metabolites were measured using standardized protocols. Multivariable logistic regression assessed MDA-ALD associations. Restricted cubic splines characterized dose-response relationships. Subgroup analyses identified vulnerable populations by sex, age, race/ethnicity, body mass index, and hyperlipidemia status. Machine learning algorithms including LightGBM were developed with nested cross-validation (to prevent data leakage during feature selection) to identify predictive biomarkers. Network toxicology integrated computationally predicted MDA targets with ALD gene expression data (GEO GSE28619), followed by pathway enrichment analyses. Three MDAs demonstrated robust positive associations: benzylmercapturic acid (BMA; OR: 1.56, 95

The prevalence of metabolic dysfunction-associated steatohepatitis (MASH) is increasing annually, which is a global public health issue. Although clinical trials are lacking, observational studies indicate that bariatric surgery can alleviate the progression of MASH. Here, we performed sleeve gastrectomy (SG) and Sham surgery on 8-week-old mice, and then fed a AMLN diet for 24 weeks to construct a diet-inducted MASH mice model after 4-week post-surgery recovery. Applying a multi-omics approach combining metagenomics, metabolomics, and transcriptomics, we found that SG prevents the development of hepatic steatosis, inflammation, and fibrosis in MASH mice not only by significantly altering the structure of gut microbiota including s_Akkermansia muciniphila, s_Alistiples dispar, g_Helicobacter and s_uc_Oscillospiraceae, but also by modulating the levels of serum metabolites including L-arginine and taurocholic acid (TCA). These results suggest that SG and the alteration of gut microbiota and its related serum metabolites can be served as the effective therapeutic strategies for MASH.

Insulin resistance (IR) is a major pathogenic factor in the progression of MASLD. In the liver, insulin suppresses gluconeogenesis and enhances de novo lipogenesis (DNL). During IR, there is a defect in insulin-mediated suppression of gluconeogenesis, but an unrestrained increase in hepatic lipogenesis persists. The mechanism of increased hepatic steatosis in IR is unclear and remains controversial. The key discrepancy is whether insulin retains its ability to directly regulate hepatic lipogenesis. Blocking insulin/IRS/AKT signaling reduces liver lipid deposition in IR, suggesting insulin can still regulate lipid metabolism; hepatic glucose metabolism that bypasses insulin’s action may contribute to lipogenesis; and due to peripheral IR, other tissues are likely to impact liver lipid deposition. We here review the current understanding of insulin’s action in governing different aspects of hepatic lipid metabolism under normal and IR states, with the purpose of highlighting the essential issues that remain unsettled.

Under normal conditions, insulin promotes hepatic de novo lipogenesis (DNL). However, during insulin resistance (IR), when insulin signalling is blunted and accompanied by hyperinsulinaemia, the promotion of hepatic DNL continues unabated and hepatic steatosis increases. Here, we show that WD40 repeat-containing protein 6 (WDR6) promotes hepatic DNL during IR. Mechanistically, WDR6 interacts with the beta-type catalytic subunit of serine/threonine-protein phosphatase 1 (PPP1CB) to facilitate PPP1CB dephosphorylation at Thr316, which subsequently enhances fatty acid synthases transcription through DNA-dependent protein kinase and upstream stimulatory factor 1. Using molecular dynamics simulation analysis, we find a small natural compound, XLIX, that inhibits the interaction of WDR6 with PPP1CB, thus reducing DNL in IR states. Together, these results reveal WDR6 as a promising target for the treatment of hepatic steatosis.

ObjectiveSome studies have demonstrated a bidirectional association between obesity and depression, whereas others have not. This discordance might be due to the metabolic health status. We aimed to determine whether the relationship between obesity and depression is dependent on metabolic health status.MethodsIn total, 9,022,089 participants were enrolled and classified as one of four obesity phenotypes: metabolically healthy nonobesity (MHNO), metabolically unhealthy nonobesity (MUNO), metabolically healthy obesity (MHO), and metabolically unhealthy obesity (MUO). We then divided the population into eight phenotypes based on obesity and the number of metabolic risk factors. Furthermore, the associations of eight phenotypes, based on obesity and specific metabolic risk factors, with depression were assessed.ResultAmong all participants, a higher risk of depression was observed for MUNO, MHO and MUO than for MHNO. The risk was highest for MUO (OR = 1.442; 95% CI = 1.432, 1.451). However, the association between MHO and depression was different for men and women (OR = 0.941, men; OR = 1.132, women). The risk of depression increased as the number of metabolic risk factors increased. Dyslipidemia was the strongest metabolic risk factor. These relationships were consistent among patients ≥ 45 years of age.ConclusionsThe increased risk of obesity-related depression appears to partly depend on metabolic health status. The results highlight the importance of a favorable metabolic status, and even nonobese populations should be screened for metabolic disorders.

Subclinical hypothyroidism is associated with cardiovascular diseases, yet the underlying mechanism remains largely unknown. Herein, in a common population (n = 1,103), TSH level was found to be independently correlated with both carotid plaque prevalence and intima-media thickness. Consistently, TSH receptor ablation in ApoE-/- mice attenuated atherogenesis, accompanied by decreased vascular inflammation and macrophage burden in atherosclerotic plaques. These results were also observed in myeloid-specific Tshr-deficient ApoE-/- mice, which indicated macrophages to be a critical target of the proinflammatory and atherogenic effects of TSH. In vitro experiments further revealed that TSH activated MAPKs (ERK1/2, p38α, and JNK) and IκB/p65 pathways in macrophages and increased inflammatory cytokine production and their recruitment of monocytes. Thus, the present study has elucidated the new mechanisms by which TSH, as an independent risk factor of atherosclerosis, aggravates vascular inflammation and contributes to atherogenesis.

Thyroxine metabolism is an important topic of pathogenesis research and treatment schedule of subclinical hypothyroidism (SCH). L-Thyroxine replacement therapy (LRT) is usually recommended for severe SCH patients only. Our previous studies reported that disordered serum lipid of mild SCH people could also benefit from LRT. However, the benefits were different among individuals, as shown by the variations in drug dosage that required to maintain thyroid-stimulating hormone (TSH) stability. Alternative pathways, such as sulfation and glucuronidation of iodothyronine, may play a role in thyroid hormones metabolism in peripheral tissues aside from thyroid. Conjugated thyroxine can be hydrolyzed and reused in tissues including gastrointestinal tract, in which gut microbiota are one of the most attractive physiological components. On this site, the roles of gut microbiota in thyroidal metabolism should be valued. In this study, a cross-sectional study was performed by analyzing 16S rDNA of gut microbiota in mild SCH patients treated with L-thyroxine or not. Subjects were divided by serum lipid level, L-thyroxine treatment, or L-thyroxine dosage, respectively. Relationship between gut microbiome and serum profile, L-thyroxine treatment, and dose were discussed. Other metabolic disorders such as type 2 diabetes and hypertension were also taken into consideration. It turned out that microbiome varied among individuals divided by dose and the increment of L-thyroxine but not by serum lipid profile. Relative abundance of certain species that were associated with thyroxine metabolism were found varied among different L-thyroxine doses although in relatively low abundance. Moreover, serum cholesterol may perform relevance effects with L-thyroxine in shaping microbiome. Our findings suggested that the differences in L-thyroxine dosage required to maintain TSH level stability, as well as the SCH development, which was displayed by the increased L-thyroxine doses in subsequent follow-up, had relationship with gut microbial composition. The reason may due to the differences in thyroxine metabolic capacity in gut. In addition, the metabolic similarity of iodothyronines and bile acid in gut also provides possibilities for the correlation between host's thyroxine and cholesterol levels. This study was registered with ClinicalTrials.gov as number NCT01848171.

Objectives: Diet-driven obesity is increasingly widespread. Its consequences pose major challenges to human health and health care systems. There are MAP kinase-interacting kinases (MNKs) in mice, MNK1 and MNK2. Studies have demonstrated that mice lacking either MNK1 or MNK2 were partially protected against high-fat diet (HFD)-induced weight gain and insulin resistance. The aims of this study were to evaluate the phenotype of mice lacking both MNKs when given an HFD, to assess whether pharmacological inhibition of MNK function also protects against diet-induced obesity (DIO) and its consequences and to probe the mechanisms underlying such protection. Methods: Male wild-type (WT) C57Bl6 mice or mice lacking both MNK1 and MNK2 (double knockout, DKO) were fed an HFD or control diet (CD) for up to 16 weeks.In a separate study, WT mice were also given an HFD for 6 weeks, after which half were treated with the recently-developed MNK inhibitor ETC-206 daily for 10 more weeks while continuing an HFD. Metabolites and other parameters were measured, and the expression of selected mRNAs and proteins was assessed. Results: MNK-DKO mice were almost completely protected from HFD-induced obesity. Higher energy expenditure (EE) in MNK-DKO mice was observed, which probably reflects the changes in a number of genes or proteins linked to lipolysis, mitochondrial function/biogenesis, oxidative metabolism, and/or ATP consumption. The MNK inhibitor ETC-206 also prevented HFD-induced weight gain, confirming that the activity of the MNKs facilitates weight gain due to excessive caloric consumption. Conclusions: Disabling MNKs in mice, either genetically or pharmacologically, strongly prevents weight gain on a calorie-rich diet. This finding likely results from increased energy utilisation, involving greater ATP consumption, mitochondrial oxidative metabolism, and other processes.

Given the high and increasing prevalence of obesity and associated disorders, such as type-2 diabetes, it is important to understand the mechanisms that regulate lipid storage and the differentiation of fat cells, a process termed adipogenesis. Using the well-established mouse 3T3-L1 in vitro model of adipogenesis, we refine how the induction of two key adipogenic transcription factors, CCAAT/enhancer-binding proteins (C/EBPs) β and δ are regulated during early adipogenesis. We identify, in the gene promoters of Cebpb and Cebpd, the DNA response elements responsible for binding transcription factors that are activated by cAMP or glucocorticoids. We also show that mitogen-activated protein kinase (MAPK)-interacting kinase 2 (MNK2; Mknk2), which plays a distinct role in diet-induced obesity, is induced during early adipogenesis and identify the functional DNA response elements responsible for regulating its expression. Mknk2 expression is maintained in differentiated 3T3-L1 adipocytes and is expressed at high levels across a range of mouse adipose tissue depots. Together, these new insights help to clarify the transcriptional programme of early adipogenesis and identify Mknk2 as one of potentially many genes up-regulated during adipogenesis.

OBJECTIVES:Nonalcoholic fatty liver disease (NAFLD) and hyperlipidemia (HL) are common metabolic disorders due to overnutrition and obesity. NAFLD is often associated with hyperlipidemia. The aim of this study was to identify and compare the erythrocyte membrane lipids profile in NAFLD patients with or without HL. Methods. A total of 112 subjects (with similar age and body mass index) were divided into four groups: (1) normal controls, (2) NAFLD alone, (3) HL alone, and (4) NAFLD combined with HL (NAFLD + HL). Lipid was extracted from the erythrocyte membrane, and lipid profiles of subjects were analyzed by liquid chromatography mass spectrometry (LC-MS). Results. Data sets from 103 subjects were adopted for lipidomic analysis. Significant changes of lipid species were observed in patient groups, especially in the HL group and NAFLD + HL group. The HL group showed increased level of most lipid species, and decreased level of most lipid species was observed in the NAFLD + HL group. The weight percent of myristic acid, stearic acid, erucic acid, and docosahexaenoic acid also showed distinct variation between different groups. Conclusions. NAFLD, HL, and NAFLD + HL all had an impact on lipid profiling of the erythrocyte membrane. The influence of NAFLD alone is less important compared with HL. Some lipids should be highlighted because of their specific role in cell function and systemic metabolism.

Abstract Nonalcoholic fatty liver disease (NAFLD) is a chronic metabolic disease with complicated mechanisms among which disturbance of mitochondria function weighs a lot. Overexpression of CypD, the initial factor in mitochondrial permeability transition pore, led to mitochondrial stress triggered hepatic TG accumulation. tRNA fragments (tRFs) are non-coding RNAs produced by precise cleavage of tRNA and divided into subtypes including tiRNA-5, tiRNA-3, tRF-5, tRF-3 and tRF-1. It is reported that tRFs, especially tiRNA-5 associated with stress. However, whether tRFs connect with NAFLD is unclear. To solve the problem, CypD overexpression models were constructed by injecting mouse AdPPIF virus to 8-weeks male C57BL/6 mice as study group (CH, n=6). Control group (WT, n=6) was established by injecting empty vector virus (AdEGFP). Then tRFs in liver were detected by high-throughput sequencing. Proportion of tRFs in CH was 40.8% higher vs WT. A connection might exist between CypD and tRFs. To validate this speculation, CypD knockdown mice were established as study group and 8-weeks male C57BL/6 as control. Then both groups were fed with 60 kcal% fat diet for 4 weeks or 8 weeks and named as CKO4, CWT4, CKO8 or CWT8 (n=6). Sequencing showed that proportion of tRFs in CKO4 and CKO8 was 42.7% and 31.2% lower vs control respectively, consistent with the speculation. Therefore, bioinformatics analysis was used to explore further. Pie plot based on proportion of each tRFs subtype showed that over 90% tRFs were tRF-5 and tiRNA-5. tiRNA-5 was 38.5% higher in CH vs WT, 27.4% lower in CKO4 vs CWT4 and 36.0% lower in CKO8 vs CWT8, indicating a connection between tiRNA-5 and CypD. Integration of pathological sections, metabolic index and more analysis were done for futher study. PCA and Venn diagram described the difference on the whole while absolute value of Pearson correlation coefficient (CH vs WT=0.84, CKO4 vs CWT4=0.93, CKO8 vs CWT8=0.73) and Scatter plot (CH vs WT =0.69, CKO4 vs CWT4=0.85, CKO8 vs CWT8=0.66) reflected the similarity between study and control group. These data indicated a connection between tRF and the severity of NAFLD assessed by pathology and metabolism index. Finally, a cutoff of fold change ≥ 1.5 was employed to identify the differentially expressed tRFs and most of those were tiRNA-5 as speculated. qRT-PCR was conducted for validation, among which fold change of AS-tDR-000666 (GlyGCC derived tiRNA-5) was significative (CH vs WT=4.29, CKO4 vs CWT4=0.22, CKO8 vs CWT8=0.05). It might be a potential biomarker related with severity of NAFLD. Because the CypD-change-induced mitochondrial oxidative stress was the direct mechanism triggering NAFLD in mouse models above, we could conclude that mitochondrial oxidative stress in NAFLD changed the profile of tRFs and tiRNA-5 had the potential to reflect the severity of mitochondrial oxidative stress in NAFLD. This study provided a new understanding of NAFLD.

Subclinical hypothyroidism (SCH) is becoming a global health problem due to its increasing prevalence and potential adverse effects, including cardiovascular diseases and nonalcoholic fatty liver disease (NAFLD). However, the association between SCH and NAFLD remains controversial. MicroRNAs (miRNAs/miRs) have been reported to be implicated in lipid metabolism disorders; however, how miRNAs regulate hepatic lipid metabolism in SCH mice remains unknown. The present study investigated miRNA alterations and proteome profiles in an SCH mouse model, which was generated by methimazole administration in mice for 16 weeks. Next, the profiles of 17 miRNAs that are critical to hepatic lipid metabolism and the proteome were investigated using reverse transcription-quantitative polymerase chain reaction and iTRAQ labeling in the liver specimens of SCH (n=9) and control (n=7) mice. Putative target prediction of miRNAs was also conducted using TargetScan and miRanda. Compared with the control mice, SCH mice had 8 miRNAs and 36 proteins with significantly different expression in the liver tissues. Furthermore, a regulatory module containing 3 miRNAs (miR-34a-5p, miR-24-3p and miR-130a-3p) and 4 proteins (thioredoxin, selenium-binding protein 2, elongation factor 1β and prosaposin) was identified. Overall, integrated analysis of miRNAs and the proteome highlighted a regulatory module between miRNAs and proteins, which, to a certain extent, may contribute to a better understanding of hepatic lipid metabolism disorders in SCH mice.

Subclinical hypothyroidism (SCH) is becoming a global health problem because of its increasing prevalence and potential adverse effects, including cardiovascular diseases and nonalcoholic fatty liver disease. However, the association remains controversial. MicroRNAs (miRNAs) have been shown to be implicated in lipid metabolism disorders. But how miRNAs regulate hepatic lipid metabolism in SCH remains unknown. We investigated miRNA alterations and proteome profiles in a SCH mouse model, which were generated with methimazole(MMI) for 16 weeks. The profiles of 17 miRNAs which are critical to hepatic lipid metabolism and proteome were investigated using quantitative PCR and iTRAQ labeling in the livers from SCH (n=9) and control mice (CON, n=7). Putative targets prediction of miRNAs was carried out using Targetscan and miRanda. Compared with the control mice, SCH mice had significantly different expressed 8 miRNAs and 36 proteins in livers. We identified a regulatory module containing 3 miRNAs (miR-34a-5p, miR-24-3p, miR-130a-3p ) and 5 proteins (Thioredoxin (Txn), Aldehyde dehydrogenase (Aldh3a2), Selenium-binding protein 2(Selenbp2), Elongation factor 1-beta( Eef1b) and Prosaposin, isoform CRA-a (Psap)). Integrated analysis of miRNA and proteome highlighted a regulatory module between miRNAs and proteins, which, to some extent, may contribute to a better understanding of hepatic lipid metabolism disorders in SCH mice.

The diversity, structure, and stability of the gut microbiota can influence hosts’ nutrition, energy, metabolism, and immunity through intestinal nutrient-sensing mechanisms, the gut-brain axis, or changes in intestinal permeability. It was reported that gut microbiota can influence hosts’ selenium concentration and 3,5,3’-triiodothyronine (T3) conversion, therefore participating in thyroid hormone metabolism. The detailed relationship of microbiota and thyroid disorder is not clear yet. In our study, an open-level randomized clinical trail (RCT) was performed in 100 people with subclinical hypothyroidism (SCH) in July 2017. Patients were randomly divided into L-thyroxine treated group (dosage was depended on thyroid function test) or untreated group. Fecal sample were collected and microbiome were analyzed by 16S rDNA high-throughput sequencing. The discrepancy of the microbiome community structure were obvious between not only the two groups, but also individuals with different drug dose within L-thyroxine group, as calculated by principle components analysis (PCA), principle coordinate analysis (PCoA) and non-metric multi-dimensional scaling (NMDS). Moreover, the microbial profile of certain patients, who were diagnosed to need to adjust their drug dose after nine months (March, 2018), showed same tendencies in PCA and NMDS analysis, which means microbiota may have correlation with the development of SCH. The abundance of some species (eg., Bacteroides, Lactobacillus, Streptococcus) showed a positive correlation with the drug dose. Those species were reported with sulfatase or glucuronidase activities, which could participate in the hydrolysis process of thyroid hormone and secondary bile acid. These results indicated that microbiota attributed in thyroxine absorption process in gut, and cholesterol or bile acid level might have correlation with thyroid dysfunction. However, in our test, we did not observe the obvious correlation between drug dose and serum cholesterol level. Taken together, these results indicated that gut microbiota may act as an important factor in influencing the occurrence, development and prognosis of thyroid dysfunction, and may partially responsible for the high risk of SCH in patients with hypercholesterolemia. The casual relationship between gut microbiota and thyroid dysfunction need to be further discussing.

Menopause is associated with dyslipidemia and an increased risk of cardio-cerebrovascular disease. The classic view assumes that the underlying mechanism of dyslipidemia is attributed to an insufficiency of estrogen. In addition to a decrease in estrogen, circulating follicle-stimulating hormone (FSH) levels become elevated at menopause. In this study, we find that blocking FSH reduces serum cholesterol via inhibiting hepatic cholesterol biosynthesis. First, epidemiological results show that the serum FSH levels are positively correlated with the serum total cholesterol levels, even after adjustment by considering the effects of serum estrogen. In addition, the prevalence of hypercholesterolemia is significantly higher in peri-menopausal women than that in pre-menopausal women. Furthermore, we generated a mouse model of FSH elevation by intraperitoneally injecting exogenous FSH into ovariectomized (OVX) mice, in which a normal level of estrogen (E2) was maintained by exogenous supplementation. Consistently, the results indicate that FSH, independent of estrogen, increases the serum cholesterol level in this mouse model. Moreover, blocking FSH signaling by anti-FSHβ antibody or ablating the FSH receptor (FSHR) gene could effectively prevent hypercholesterolemia induced by FSH injection or high-cholesterol diet feeding. Mechanistically, FSH, via binding to hepatic FSHRs, activates the Gi2α/β-arrestin-2/Akt pathway and subsequently inhibits the binding of FoxO1 with the SREBP-2 promoter, thus preventing FoxO1 from repressing SREBP-2 gene transcription. This effect, in turn, results in the upregulation of SREBP-2, which drives HMGCR nascent transcription and de novo cholesterol biosynthesis, leading to the increase of cholesterol accumulation. This study uncovers that blocking FSH signaling might be a new strategy for treating hypercholesterolemia during menopause, particularly for women in peri-menopause characterized by FSH elevation only.

Non-alcoholic fatty liver disease (NAFLD) is a chronic and progressive liver disease with an increased risk of morbidity and mortality. However, so far no specific pharmacotherapy has been approved. Gynostemma pentaphylla (Thunb.) Makino (GP) is a traditional Chinese medicine that is widely used against hyperlipemia as well as hyperglycemia. This study aims to evaluate the effect of GP on NAFLD and explore the possible mechanism.

Physiological opening of the mitochondrial permeability transition pore (mPTP) is indispensable for maintaining mitochondrial function and cell homeostasis, but the role of the mPTP and its initial factor, cyclophilin D (CypD), in hepatic steatosis is unclear. Here, we demonstrate that excess mPTP opening is mediated by an increase of CypD expression induced hepatic mitochondrial dysfunction. Notably, such mitochondrial perturbation occurred before detectable triglyceride accumulation in the liver of high-fat diet-fed mice. Moreover, either genetic knockout or pharmacological inhibition of CypD could ameliorate mitochondrial dysfunction, including excess mPTP opening and stress, and down-regulate the transcription of sterol regulatory element-binding protein-1c, a key factor of lipogenesis. In contrast, the hepatic steatosis in adenoviral overexpression of CypD-infected mice was aggravated relative to the control group. Blocking p38 mitogen-activated protein kinase or liver-specific Ire1 knockout could resist CypD-induced sterol regulatory element-binding protein-1c expression and steatosis. Importantly, CypD inhibitor applied prior to or after the onset of triglyceride deposition substantially prevented or ameliorated fatty liver. Conclusion: CypD stimulates mPTP excessive opening, subsequently causing endoplasmic reticulum stress through p38 mitogen-activated protein kinase activation, and results in enhanced sterol regulatory element-binding protein-1c transcription and hepatic steatosis. (Hepatology 2018;68:62-77).

AIMS:To comprehensively review, identify and critically assess the performance of models predicting the incidence and progression of periodontitis.METHODS:Electronic searches of the MEDLINE via PubMed, EMBASE, DOSS, Web of Science, Scopus and ProQuest databases, and hand searching of reference lists and citations were conducted. No date or language restrictions were used. The Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies checklist was followed when extracting data and appraising the selected studies.RESULTS:Of the 2,560 records, five studies with 12 prediction models and three risk assessment studies were included. The prediction models showed great heterogeneity precluding meta-analysis. Eight criteria were identified for periodontitis incidence and progression. Four models from one study examined the incidence, while others assessed progression. Age, smoking and diabetes status were common predictors used in modelling. Only two studies reported external validation. Predictive performance of the models (discrimination and calibration) was unable to be fully assessed or compared quantitatively. Nevertheless, most models had "good" ability to discriminate between people at risk for periodontitis.CONCLUSIONS:Existing predictive modelling approaches were identified. However, no studies followed the recommended methodology, and almost all models were characterized by a generally poor level of reporting.

After activation, G protein-coupled receptors (GPCRs) are desensitized by β-arrestins (ARRBs). Moreover, ARRBs can initiate a second wave of signaling independent of G proteins. Thyroid-stimulating hormone receptor (TSHR) is one of the GPCR members. In our previous study, TSHR was identified in the liver; the major role of TSHR in cholesterol metabolism was illustrated, as TSH could regulate hepatic cholesterol metabolism via cAMP/PKA/CREB/HMGCR and SREBP2/HNF4α/CYP7A1 pathways. It has been reported that ARRB2 predominates over ARRB1 in TSHR internalization. However, the significance of ARRBs in TSH-initiated cholesterol metabolism has not been illustrated. In our study, the effects of ARRBs on TSH-regulated cholesterol metabolism are investigated. ARRB1/2 was genetically inactivated in C57BL/6 mice and HepG2 cell line, respectively. Cholesterol levels in arrestin-knockout mice and arrestin-knockdown cells were measured. Molecules participating in cholesterol metabolism were analyzed. It turned out that deficiencies in ARRB1 led to decreased cholesterol levels and decreased TSH-stimulated AKT phosphorylation. Subsequently, the inhibitory effect on CYP7A1 by SREBP2 was reduced due to lowered mature SREBP2 level. Other than the failures of TSH in ARRB-knockdown cells, the AKT activator SC79 could enhance AKT phosphorylation and mature SREBP2 level. Our results demonstrate that ARRBs, especially ARRB1, are involved in TSH-regulated cholesterol metabolism through the AKT pathway.