Activation of NR1H3 signaling pathways by psoralidin attenuates septic myocardial injury

Sepsis can cause various organ dysfunction, which heart failure may be associated with significant mortality. Psoralidin (PSO), one of the main bioactive compounds from the seeds of Psoralea corylifolia L, exhibits remarkable protective effects in diseases, including cancer, osteoporosis, and depression. Recently, NR1H3 is one of the emerging nuclear receptors targets for the various drugs. This study first reported the role of PSO in septic myocardial injury, which was mainly attributed to the NR1H3-dependent manner. NR1H3 knockout mice subjected to cecal ligation and puncture (CLP) were used to investigate the involvement of NR1H3 in PSO protection evaluate. Our results showed that PSO prominently improved cardiac function, blood routine and blood biochemistry, attenuated inflammation, inhibited oxidative stress, improved mitochondrial function, regulated ERS, suppressed apoptosis, and increased NR1H3 and p-AMPK levels. However, NR1H3 knockout reversed the positive role of PSO in septic mice. Furthermore, activation of NR1H3 by T0901317 also increased the activity of AMPK and ACC in the HL-1 cardiomyocytes, indicating the regulatory relationship between NR1H3 and AMPK signaling. This study first demonstrated the beneficial effect of PSO in septic myocardial injury through activation of NR1H3/AMPK pathway.

Low expression of NR1H3 correlates with macrophage infiltration and indicates worse survival in breast cancer

Background: Nuclear receptor NR1H3 is a key regulator of macrophage function and lipid homeostasis. Here, we aimed to visualize the prognostic value and immunological characterization of NR1H3 in breast cancer. Methods: The expression pattern and prognostic value of NR1H3 were analyzed via multiple databases, including TIMER2, GEPIA2 and Kaplan-Meier Plotter. TISIDB, TIMER2 and immunohistochemical analysis were used to investigate the correlation between NR1H3 expression and immune infiltration. GO enrichment analysis, KEGG analysis, Reactome analysis, ConsensusPathDB and GeneMANIA were used to visualize the functional enrichment of NR1H3 and signaling pathways related to NR1H3. Results: We demonstrated that the expression of NR1H3 was significantly lower in breast cancer compared with adjacent normal tissues. Kaplan-Meier survival curves showed shorter overall survival in basal breast cancer patients with low NR1H3 expression, and poorer prognosis of relapse-free survival in breast cancer patients with low NR1H3 expression. NR1H3 was mainly expressed in immune cells, and its expression was closely related with infiltrating levels of tumor-infiltrating immune cells in breast cancer. Additionally, univariate and multivariate analysis indicated that the expression of NR1H3 and the level of macrophage infiltration were independent prognostic factors for breast cancer. Gene interaction network analysis showed the function of NR1H3 involved in regulating of innate immune response and macrophage activation. Moreover, NR1H3 may function as a predictor of chemoresponsiveness in breast cancer. Conclusion: These findings suggest that NR1H3 serves as a prognostic biomarker and contributes to the regulation of macrophage activation in breast cancer.

Silibinin protects against sepsis and septic myocardial injury in an NR1H3-dependent pathway

Cardiac dysfunction resulting from sepsis causes high morbidity and mortality. Silibinin (SIL) is a secondary metabolite isolated from the seed extract of the milk thistle plant with various properties, including anti-inflammatory, anti-fibrotic, and anti-oxidative activities. This study, for the first time, examined the effects and mechanisms of SIL pretreatment, posttreatment and in combination with classical antibiotics in septic myocardial injury. The survival rate, sepsis score, anal temperature, routine blood parameters, blood biochemical parameters, cardiac function indicators, pathological indicators of myocardial injury, NR1H3 signaling pathway, and several sepsis-related signaling pathways were detected 8 h following cecal ligation and puncture (CLP). Our results showed that SIL pretreatment showed a significant protective effect on sepsis and septic myocardial injury, which was explained by the attenuation of inflammation, inhibition of oxidative stress, improvement of mitochondrial function, regulation of endoplasmic reticulum stress (ERS), and activation of the NR1H3 pathway. SIL posttreatment and the combination of SIL and azithromycin (AZI) showed a certain therapeutic effect. RNA-seq detection further clarified the myocardial protective mechanisms of SIL. Taken together, this study provides a theoretical basis for the application strategy and combination of SIL in septic myocardial injury.

Subcutaneous adipose tissue splice quantitative trait loci reveal differences in isoform usage associated with cardiometabolic traits

Alternate splicing events can create isoforms that alter gene function, and genetic variants associated with alternate gene isoforms may reveal molecular mechanisms of disease. We used subcutaneous adipose tissue of 426 Finnish men from the METSIM study and identified splice junction quantitative trait loci (sQTLs) for 6,077 splice junctions (FDR < 1%). In the same individuals, we detected expression QTLs (eQTLs) for 59,443 exons and 15,397 genes (FDR < 1%). We identified 595 genes with an sQTL and exon eQTL but no gene eQTL, which could indicate potential isoform differences. Of the significant sQTL signals, 2,114 (39.8%) included at least one proxy variant (linkage disequilibrium r2 > 0.8) located within an intron spanned by the splice junction. We identified 203 sQTLs that colocalized with 141 genome-wide association study (GWAS) signals for cardiometabolic traits, including 25 signals for lipid traits, 24 signals for body mass index (BMI), and 12 signals for waist-hip ratio adjusted for BMI. Among all 141 GWAS signals colocalized with an sQTL, we detected 26 that also colocalized with an exon eQTL for an exon skipped by the sQTL splice junction. At a GWAS signal for high-density lipoprotein cholesterol colocalized with an NR1H3 sQTL splice junction, we show that the alternative splice product encodes an NR1H3 transcription factor that lacks a DNA binding domain and fails to activate transcription. Together, these results detect splicing events and candidate mechanisms that may contribute to gene function at GWAS loci.

LXRα-mediated downregulation of EGFR suppress colorectal cancer cell proliferation

Liver X receptors (LXRs) are members of the nuclear receptor family, including the LXRα (NR1H3) and LXRβ (NR1H2) subtypes, which are related to the metabolism of glucose and cholesterol and possess anti-inflammatory functions. Mounting evidence has linked LXRs to the inhibition of cell proliferation in a variety of cancers. We revealed a differential distribution for NR1H3, but not for NR1H2, in colorectal cancer and adjacent normal tissues. We found that NR1H3 enhanced the inhibitory action of GW3965, an agonist of LXRs, on the proliferation of colorectal cancer cells. Upregulation of NR1H3 enhanced the inhibition of cell proliferation by GW3965 while silencing of NR1H3 attenuated the inhibitory effect of GW3965 on cell proliferation. Bioinformatic prediction and luciferase assays showed that NR1H3 was able to inhibit the activity of the epidermal growth factor receptor (EGFR) promoter. Moreover, we demonstrated that activation of NR1H3 inhibited the growth of transplanted tumors in an animal experiment, with the inhibition accompanied by downregulation of EGFR. Our findings suggest that NR1H3 controls cell proliferation by affecting EGFR promoter activity. The high expression of EGFR was due to the downregulation of NR1H3 which is a novel molecular mechanism in the development of colorectal cancer.

NR1H3 Expression is a Prognostic Factor of Overall Survival for Patients with Muscle-Invasive Bladder Cancer

Background: Nuclear receptors (NRs) are a class of transcription factors that regulate many cellular functions through manipulation of gene expression and also play important roles in tumorigenesis, proliferation, progression and prognosis in various kinds of cancers according to recent studies. This work aimed to determine the predictive ability of NRs in muscle-invasive bladder cancer (MIBC).

Patients and methods: A total of 308 MIBC patients with complete clinicopathological and RNASeq data from The Cancer Genome Atlas (TCGA) cohort were collected for filtration. Genes showed clear correlations with overall survival (OS) and recurrence free survival (RFS) were further validated in 123 MIBC patients recruited consecutively from 2008 to 2012 in Fudan University Shanghai Cancer Center (FUSCC) cohort. Cox proportional hazards regression model and Kaplan-Meier plot were used to assess the relative factors.

Results: In TCGA cohort, we found that high NR1H3 (HR=0.779, 95% CI: 0.634 - 0.957), NR2C1 (HR=0.673, 95% CI: 0.458 - 0.989) and NR2F6 (HR=0.750, 95% CI: 0.574 - 0.980) expressions were independent factors of favorable OS, while only low NR1H3 (log-rank test, P=0.0076) and NR2F6 (log-rank test, P=0.0395) expressions had the ability to predict poor prognosis for RFS. Further, in FUSCC validating cohort, we confirmed that low NR1H3 expression level was independent factor of poor OS (HR=1.295, 95% CI: 1.064 - 1.576) and it had the ability to predict poor RFS (log-rank test, P=0.0059).

Conclusions: Low NR1H3 expression level is an independent prognostic factor of poor OS, and can also predict worse RFS in MIBC patients. Our “TCGA filtrating and local database validating” model can help reveal more prognostic biomarkers and cast a new light in understanding certain gene function in MIBC.

The association of NR1H3 gene with lipid deposition in the pig

Background

Nuclear receptor subfamily 1, group H, member 3 (NR1H3, an alias for Liver X receptor α, LXRα) is a member of the LXR nuclear receptor super family and is an important regulator of lipid and fatty acid accumulation in the liver, adipose and skeletal muscle.

Methods

In this study, single-nucleotide polymorphisms (SNPs) from six populations of pig (Sus scrofa) were screened by PCR-sequencing and genotyped, and its association with backfat thickness was analyzed in a population of New Huai line (NHP, n = 117). In addition, quantitative real-time PCR and western blot were used to measure expression of NR1H3 in the liver tissue, backfat and longissimus dorsi muscle of DSP (n = 10), TP (n = 10) and YY (n = 10) pigs.

Results

Three SNPs (exon2-C105T, exon2-G106C, and exon5-A201C) were screened and exon5-A201C was identified; the genotype frequencies were significantly different between indigenous and introduced breeds. The CC genotype was associated with higher backfat thickness than the AA and AC genotypes in the NYP. NR1H3 mRNA and protein expression were higher in the liver and longissimus dorsi of DSP and TP than in those of YY. This increased NR1H3 expression might be associated with higher lipid deposition. NR1H3 expression in the backfat of YY was not lower than that in DSP or TP, which might because NR1H3 has an alternative regulatory function for lipid metabolism in the subcutaneous fat of pigs.

Conclusions

Our results suggest that allele A of the exon5-A201C in NR1H3 may promote a reduction in backfat thickness, and differences in NR1H3 expression may be associated with differences in lipid deposition capacity among pigs.