Shuang-Xia Zhao

Stevioside ameliorates high-fat diet-induced insulin resistance and adipose tissue inflammation by downregulating the NF-κB pathway

Accumulating evidence suggests that adipose tissue is the main source of pro-inflammatory molecules that predispose individuals to insulin resistance. Stevioside (SVS) is a widely used sweetener with multiple beneficial effects for diabetic patients. In this study, we investigated the effect of SVS on insulin resistance and the pro-inflammatory state of adipose tissue in mice fed with a high-fat diet (HFD). Oral administration of SVS for 1month had no effect on body weight, but it significantly improved fasting glucose, basal insulin levels, glucose tolerance and whole body insulin sensitivity. Interestingly, these changes were accompanied with decreased expression levels of several inflammatory cytokines in adipose tissue, including TNF-α, IL6, IL10, IL1β, KC, MIP-1α, CD11b and CD14. Moreover, macrophage infiltration in adipose tissue was remarkably reduced by SVS. Finally, SVS significantly suppressed the nuclear factor-kappa b (NF-κB) signaling pathway in adipose tissue. Collectively, these results suggested that SVS may ameliorate insulin resistance in HFD-fed mice by attenuating adipose tissue inflammation and inhibiting the NF-κB pathway.

A splice site mutation combined with a novel missense mutation of LHCGR cause male pseudohermaphroditism.

Leydig cell hypoplasia (LCH) is a rare form of male pseudohermaphroditism caused by inactivating mutations in the luteinizing hormone receptor gene (LHCGR). The majority of LHCGR mutations are located in the coding sequence, resulting in impairment of either LH/CG binding or signal transduction. We report a Chinese family with two siblings (46, XY and 46, XX) carrying a missense mutation (c. 455 T>C, p. Ile152Thr) and a splice site mutation (c. 537‐3 C>A). Computational analysis of the missense mutation in the three‐dimensional structural model predicted it might influence the distribution of hydrogen bonds and intermolecular contacts between the hormone and receptor. Consistent with these findings, in vitro mutant analysis revealed a marked impairment of human chorionic gonadotropin binding and signal transduction. The splice‐acceptor mutation (c. 537‐3 C>A) resulted in abnormal splicing of LHCGR mRNA, skipping exon 7. This report expands the genotypic spectrum of LHCGR mutations, with relevant implications for the molecular analysis of this gene.

A refined study of FCRL genes from a genome-wide association study for Graves' disease.

To pinpoint the exact location of the etiological variant/s present at 1q21.1 harboring FCRL1-5 and CD5L genes, we carried out a refined association study in the entire FCRL region in 1,536 patients with Graves’ disease (GD) and 1,516 sex-matched controls by imputation analysis, logistic regression, and cis-eQTL analysis. Among 516 SNPs with P<0.05 in the initial GWAS scan, the strongest signals associated with GD and correlated to FCRL3 expression were located at a cluster of SNPs including rs7528684 and rs3761959. And the allele-specific effects for rs3761959 and rs7528684 on FCRL3 expression level revealed that the risk alleles A of rs3761959 and C of rs7528684 were correlated with the elevated expression level of FCRL3 whether in PBMCs or its subsets, especially in CD19+ B cells and CD8+ T subsets. Next, the combined analysis with 5,300 GD cases and 4,916 control individuals confirmed FCRL3 was a susceptibility gene of GD in Chinese Han populations, and rs3761959 and rs7528684 met the genome-wide association significance level (Pcombined = 2.27×10−12 and 7.11×10−13, respectively). Moreover, the haplotypes with the risk allele A of rs3761959 and risk allele C of rs7528684 were associated with GD risk. Finally, our epigenetic analysis suggested the disease-associated C allele of rs7528684 increased affinity for NF-KB transcription factor. Above data indicated that FCRL3 gene and its proxy SNP rs7528684 may be involved in the pathogenesis of GD by excessive inhibiting B cell receptor signaling and the impairment of suppressing function of Tregs.

Phenotypic and molecular characteristics in eleven Chinese patients with 5α-reductase Type 2 deficiency

Steroid 5α‐reductase type 2 deficiency (5α‐RD2) is a male‐limited, autosomal recessive inherited disease. Affected 46, XY individuals usually present with ambiguous genitalia at birth. An early and precise diagnosis is of great value to the long‐term prognosis of the disease.

Genetic Heterogeneity of Susceptibility Gene in Different Ethnic Populations: Refining Association Study of PTPN22 for Graves' Disease in a Chinese Han Population

In our previous studies, we presumed subtypes of Graves’ disease (GD) may be caused by different major susceptibility genes or different variants of a single susceptibility gene. However, more evidence is needed to support this hypothesis. Single-nucleotide polymorphism (SNP) rs2476601 in PTPN22 is the susceptibility loci of GD in the European population. However, this polymorphism has not been found in Asian populations. Here, we investigate whether PTPN22 is the susceptibility gene for GD in Chinese population and further determine the susceptibility variant of PTPN22 in GD. We conducted an imputation analysis based on the results of our genome-wide association study (GWAS) in 1,536 GD patients and 1,516 control subjects. Imputation revealed that 255 common SNPs on a linkage disequilibrium (LD) block containing PTPN22 were associated with GD (P<0.05). Nine tagSNPs that captured the 255 common variants were selected to be further genotyped in a large cohort including 4,368 GD patients and 4,350 matched controls. There was no significant difference between the nine tagSNPs (P>0.05) in either the genotype distribution or allelic frequencies between patients and controls in the replication study. Although the combined analysis exhibited a weak association signal (P combined = 0.003263 for rs3811021), the false positive report probability (FPRP) analysis indicated it was most likely a false positive finding. Our study did not support an association of common SNPs in PTPN22 LD block with GD in Chinese Han population. This suggests that GD in different ethnic population is probably caused by distinct susceptibility genes.

Aldosterone directly affects apelin expression and secretion in adipocytes

There is a high incidence of metabolic syndrome among patients with primary aldosteronism (PA), which has recently been associated with an unfavorable cardiometabolic profile. However, the underlying mechanisms have not been clarified in detail. Characterizing aldosterone (Ald) target genes in adipocytes will help us to elucidate the deleterious effects associated with excess Ald. Apelin, a novel adipokine, exerts beneficial effects on obesity-associated disorders and cardiovascular homeostasis. The objective of this study was to investigate the effects of high Ald levels on apelin expression and secretion and the underlying mechanisms involved in adipocytes. In vivo, a single-dose Ald injection acutely decreased apelin serum levels and adipose tissue apelin production, which demonstrates a clear inverse relationship between the levels of plasma Ald and plasma apelin. Experiments using 3T3-L1 adipocytes showed that Ald decreased apelin expression and secretion in a time- and dose-dependent manner. This effect was reversed by glucocorticoid receptor (GR) antagonists or GR (NR3C1) knockdown; furthermore, putative HREs were identified in the apelin promoter. Subsequently, we verified that both glucocorticoids and mineralocorticoids regulated apelin expression through GR activation, although no synergistic effect was observed. Additionally, detailed potential mechanisms involved a p38 MAPK signaling pathway. In conclusion, our findings strengthen the fact that there is a direct interaction between Ald and apelin in adipocytes, which has important implications for hyperaldosteronism or PA-associated cardiometabolic syndrome and hoists apelin on the list of potent therapeutic targets for PA.

Multiregion sequencing reveals the intratumor heterogeneity of driver mutations in TP53‐driven non‐small cell lung cancer

Intratumor heterogeneity (ITH) in non‐small cell lung cancer (NSCLC) may account for resistance after a period of targeted therapies because drugs destroy only a portion of tumor cells. The recognition of ITH helps identify high‐risk patients to make effective treatment decisions. However, ITH studies are confounded by interpatient heterogeneity in NSCLC and a large amount of passenger mutations. To address these issues, we recruited NSCLC patients carrying TP53 mutations and selected driver mutations within recurrently mutated genes in NSCLC. A total of 12‐paired normal‐tumor tissues were subjected to whole‐genome/whole‐exome sequencing. From these, 367 non‐silent mutations were selected as driver mutations and deeply sequenced in 61 intratumoral microdissections. We identified a universal prevalence of heterogeneity in all 12 tumors, indicating branched evolution. Although TP53 mutations were observed in single biopsy of all 12 tumors, most tumors consist of both TP53 mutated and non‐mutated cells in separate regions within the same tumor. This suggests the late molecular timing of the acquisition of TP53 mutations; therefore, the detection of TP53 mutations in a single biopsy may simply not reflect the early malignant potential. In addition, we identified regions of loss of heterozygosity surrounding TP53 and CDKN2A mutations in tumor 711, which also exhibited heterogeneity in different regional samples. Because the ITH of driver mutations likely has clinical consequences, further efforts are needed to limit the impact of ITH and to improve therapeutic efficiency, which will benefit NSCLC patients receiving targeted treatments.

Mimecan, a Hormone Abundantly Expressed in Adipose Tissue, Reduced Food Intake Independently of Leptin Signaling

Adipokines such as leptin play important roles in the regulation of energy metabolism, particularly in the control of appetite. Here, we describe a hormone, mimecan, which is abundantly expressed in adipose tissue. Mimecan was observed to inhibit food intake and reduce body weight in mice. Intraperitoneal injection of a mimecan-maltose binding protein (-MBP) complex inhibited food intake in C57BL/6J mice, which was attenuated by pretreatment with polyclonal antibody against mimecan. Notably, mimecan-MBP also induced anorexia in Ay/a and db/db mice. Furthermore, the expression of interleukin (IL)-1β and IL-6 was up-regulated in the hypothalamus by mimecan-MBP, as well as in N9 microglia cells by recombinant mouse mimecan. Taken together, the results suggest that mimecan is a satiety hormone in adipose tissue, and that mimecan inhibits food intake independently of leptin signaling by inducing IL-1β and IL-6 expression in the hypothalamus.

Identification of a locus (DSP2) for disseminated superficial porokeratosis at chromosome 12q21.2-24.21.

Porokeratosis is a rare disorder of epidermal keratinization that is characterized by the presence of a border called the cornoid lamella. Disseminated superficial porokeratosis (DSP) is a subtype of porokeratosis, which is inherited as an autosomal trait. The first locus for DSP was localized to chromosome 18p11.3, but no causative gene has yet been identified. In this study, we recruited and analysed a large six‐generation Chinese family with autosomal dominant DSP. The genome‐wide screening identified a maximum two‐point LOD score of 3.06 at θ = 0.00 with the microsatellite marker D12S78. Fine mapping and haplotype analysis defined a critical region of 38 Mb between D12S326 and D12S79 on chromosome 12q21.2–24.21, which is a probable second locus identified for DSP (DSP2). We sequenced 50 candidate genes in this region, but no causative mutation was found. This study provides a map location for isolation of a gene causing DSP.

Influence of visceral adiposity on ghrelin secretion and expression in rats during fasting.

Although circulating ghrelin levels correlate inversely with adiposity at baseline, little is known about the effect of percent visceral adipose tissue value (PVATV) on ghrelin expression and secretion in response to fasting. Our study demonstrated that ghrelin increased with 24-h fasting in rats with the lowest PVATV (less than 6%), after 3 days in rats with intermediate PVATV (6-9%) and 5 days in rats with the highest PVATV (greater than 9%). Ghrelin mRNA in the stomach was increased after 3 days in low-PVATV (5.8+/-0.9%) rats but not in high-PVATV (14+/-1.6%) rats. Therefore, both ghrelin secretion and mRNA were delayed in response to fasting in rats with increased visceral fat. In rats matched for PVATV, but with different body weights, the fasting induced similar levels of increased ghrelin while in rats with different PVATV ghrelin secretion was different in response to fasting, even when body weights were matched in two groups. These data suggested that the initial PVATV, not lean mass, was related to the pattern of plasma ghrelin in response to fasting in rats.