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Toxicogenomic analysis suggests chemical-induced sexual dimorphism in the expression of metabolic genes in zebrafish liver.

ABSTRACT: Differential gene expression in two sexes is widespread throughout the animal kingdom, giving rise to sex-dimorphic gene activities and sex-dependent adaptability to environmental cues, diets, growth and development as well as susceptibility to diseases. Here, we present a study using a toxicogenomic approach to investigate metabolic genes that show sex-dimorphic expression in the zebrafish liver triggered by several chemicals. Our analysis revealed that, besides the known genes for xenobiotic metabolism, many functionally diverse metabolic genes, such as ELOVL fatty acid elongase, DNA-directed RNA polymerase, and hydroxysteroid dehydrogenase, were also sex-dimorphic in their response to chemical treatments. Moreover, sex-dimorphic responses were also observed at the pathway level. Pathways belonging to xenobiotic metabolism, lipid metabolism, and nucleotide metabolism were enriched with sex-dimorphically expressed genes. We also observed temporal differences of the sex-dimorphic responses, suggesting that both genes and pathways are differently correlated during different periods of chemical perturbation. The ubiquity of sex-dimorphic activities at different biological hierarchies indicate the importance and the need of considering the sex factor in many areas of biological researches, especially in toxicology and pathology.

SUBMITTER: Zhang X

PROVIDER: S-EPMC3525581 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Toxicogenomic analysis suggests chemical-induced sexual dimorphism in the expression of metabolic genes in zebrafish liver.

Zhang Xun X Ung Choong Yong CY Lam Siew Hong SH Ma Jing J Chen Yu Zong YZ Zhang Louxin L Gong Zhiyuan Z Li Baowen B

PloS one 20121218 12

Differential gene expression in two sexes is widespread throughout the animal kingdom, giving rise to sex-dimorphic gene activities and sex-dependent adaptability to environmental cues, diets, growth and development as well as susceptibility to diseases. Here, we present a study using a toxicogenomic approach to investigate metabolic genes that show sex-dimorphic expression in the zebrafish liver triggered by several chemicals. Our analysis revealed that, besides the known genes for xenobiotic m ...[more]

PMID: 23272195

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Project description:The growth hormone (GH)-activated transcription factor signal transducer and activator of transcription 5b (STAT5b) is a key regulator of sexually dimorphic gene expression in the liver. Suppression of hepatic STAT5b signaling is associated with lipid metabolic dysfunction leading to steatosis and liver cancer. In the companion publication, a STAT5b biomarker gene set was identified and used in a rank-based test to predict both increases and decreases in liver STAT5b activation status/function with high (? 97%) accuracy. Here, this computational approach was used to identify chemicals and hormones that activate (masculinize) or suppress (feminize) STAT5b function in a large, annotated mouse liver and primary hepatocyte gene expression compendium. Exposure to dihydrotestosterone and thyroid hormone caused liver masculinization, whereas glucocorticoids, fibroblast growth factor 15, and angiotensin II caused liver feminization. In mouse models of diabetes and obesity, liver feminization was consistently observed and was at least partially reversed by leptin or resveratrol exposure. Chemical-induced feminization of male mouse liver gene expression profiles was a relatively frequent phenomenon: of 156 gene expression biosets from chemically-treated male mice, 29% showed feminization of liver STAT5b function, while <1% showed masculinization. Most (93%) of the biosets that exhibited feminization of male liver were also associated with activation of one or more xenobiotic-responsive receptors, most commonly constitutive activated receptor (CAR) or peroxisome proliferator-activated receptor alpha (PPAR?). Feminization was consistently associated with increased expression of peroxisome proliferator-activated receptor gamma (Pparg) but not other lipogenic transcription factors linked to steatosis. GH-activated STAT5b signaling in mouse liver is thus commonly altered by diverse chemicals, and provides a linkage between chemical exposure and dysregulated gene expression associated with adverse effects on the liver.

Project description:The liver is one of the most sex-dimorphic organs in both oviparous and viviparous animals. In order to understand the molecular basis of the difference between male and female livers, high-throughput RNA-SAGE (serial analysis of gene expression) sequencing was performed for zebrafish livers of both sexes and their transcriptomes were compared. Both sexes had abundantly expressed genes involved in translation, coagulation and lipid metabolism, consistent with the general function of the liver. For sex-biased transcripts, from in addition to the high enrichment of vitellogenin transcripts in spawning female livers, which constituted nearly 80% of total mRNA, it is apparent that the female-biased genes were mostly involved in ribosome/translation, estrogen pathway, lipid transport, etc, while the male-biased genes were enriched for oxidation reduction, carbohydrate metabolism, coagulation, protein transport and localization, etc. Sexual dimorphism on xenobiotic metabolism and anti-oxidation was also noted and it is likely that retinol x receptor (RXR) and liver x receptor (LXR) play central roles in regulating the sexual differences of lipid and cholesterol metabolisms. Consistent with high ribosomal/translational activities in the female liver, female-biased genes were significantly regulated by two important transcription factors, Myc and Mycn. In contrast, Male livers showed activation of transcription factors Ppargc1b, Hnf4a, and Stat4, which regulate lipid and glucose metabolisms and various cellular activities. The transcriptomic responses to sex hormones, 17β-estradiol (E2) or 11-keto testosterone (KT11), were also investigated in both male and female livers and we found that female livers were relatively insensitive to sex hormone disturbance, while the male livers were readily affected. E2 feminized male liver by up-regulating female-biased transcripts and down-regulating male-biased transcripts. The information obtained in this study provides comprehensive insights into the sexual dimorphism of zebrafish liver transcriptome and will facilitate further development of the zebrafish as a human liver disease model.

Project description:Purpose: To conduct a transcriptomic study of gene oscillations in mouse liver by RNA sequencing of total RNA samples from 6 different time points across the day. Specific interest is to see whether sex is a factor in large scale gene oscillations under ad-libitum control conditions and in response to caloric restriction diet, since caloric restriction was previously reported to affect gene oscillation Methods: Total RNA was isolated from 20 mg mouse liver tissue using mini spin column QIAGEN RNeasy Mini Kit (Ref #74104, Lot#163035346, Hilden, Germany) according to the manufacturer’s protocol. Sample purity was checked on Nano Drop 2000 (Thermo Fisher Scientific, Waltham, MA, USA) with 260/280 ratio ≥ 2.0 and 260/230 ratio ≥ 2.0 for every sample. Each sample used for the analysis had RNA integrity number > 7. The RNA sequencing was performed by Novogene Corporation Inc (Sacramento, CA, USA). After sample quality control, non-directional – polyA enrichment library was prepared using NEBNext Ultra™ II RNA Library Prep Kit for Illumina, and 50M reads (150bp, paired end) per sample were generated on Illumina NovaSeq 6000 platform. RNA-seq reads were mapped to the mouse protein coding genes (Ensembl: Mus_musculus; GRCm38) using Bowtie allowing up to 2-mismatches. The gene expected read counts and Transcripts Per Million (TPM) were estimated by RSEM (v1.2.3). The TPMs were further normalized by EBSeq R package to correct potential batch effect. Results: We have performed RNA sequencing analysis of mouse livers on Ad-libitum and timed Caloric Restriction diet across 6 time points in 24h. The results of subsequent compareRhythms analysis (R package) revealed that circadian rhythms in total RNA liver transcriptome are different between sexes of mice in both the number of oscillating genes and phase under ad-libitum diet. Caloric restriction increased the number of oscillating genes in both sexes and resulted in a larger overlap of rhythmic transcriptome between sexes, but did not eliminate the difference completely. The response of transcriptome to caloric restriction in terms of gain or loss of rhythm in gene expression profiles was also different between sexes. Additionally, we have shown that the lack of data stratification by sex might result in the failure to detect rhythmic changes in expression of some genes. Conclusions: Our study represents the first systematic analysis of the effect of sex on circadian rhythms of liver transcriptome under ad libitum and caloric restriction diets. We have shown that sex based differences exist in rhythmic transcriptome, as well as in the response of rhythmic transcriptome to diet. We are providing the data useful for both circadian and metabolic researchers and point out the gene candidates which may not be identified as rhythmic, if the data is not stratified by sex. With the help of GO analysis we have concluded that sex also influences the preference towards different processes to be regulated in rhythmic manner on transcriptional level - fatty acid metabolism and protein transport in males vs nucleic acid metabolism and RNA processing in females on ad-libitum diet. On calorie-restricted diet nucleic acid metabolism and RNA processing were enriched in males vs protein transport and signal transduction in females on calorie-restricted diet. These findings highlight a complex interaction of sex and diet in their effect on circadian rhythms in liver gene expression. All of the data from sequenced RNA samples from MALE liver were previously uploaded with the GSE211975 dataset. The current dataset only contains RNA-seq samples from FEMALE liver.

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Toxicogenomic analysis suggests chemical-induced sexual dimorphism in the expression of metabolic genes in zebrafish liver.

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Toxicogenomic analysis suggests chemical-induced sexual dimorphism in the expression of metabolic genes in zebrafish liver.

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