Reduced plasma glucose by asparagine synthetase knockdown in the mouse liver

Modifications of the GH Axis Reveal Unique Sexually Dimorphic Liver Signatures for Lcn13, Asns, Hamp2, Hao2, and Pgc1a

Growth hormone (GH) modifies liver gene transcription in a sexually dimorphic manner to meet liver metabolic demands related to sex; thus, GH dysregulation leads to sex-biased hepatic disease. We dissected the steps of the GH regulatory cascade modifying GH-dependent genes involved in metabolism, focusing on the male-predominant genes Lcn13, Asns, and Cyp7b1, and the female-predominant genes Hao2, Pgc1a, Hamp2, Cyp2a4, and Cyp2b9. We explored mRNA expression in 2 settings: (i) intact liver GH receptor (GHR) but altered GH and insulin-like growth factor 1 (IGF1) levels (NeuroDrd2KO, HiGH, aHepIGF1kd, and STAT5bCA mouse lines); and (ii) liver loss of GHR, with or without STAT5b reconstitution (aHepGHRkd, and aHepGHRkd + STAT5bCA). Lcn13 was downregulated in males in most models, while Asns and Cyp7b1 were decreased in males by low GH levels or action, or constant GH levels, but unexpectedly upregulated in both sexes by the loss of liver Igf1 or constitutive Stat5b expression. Hao, Cyp2a4, and Cyp2b9 were generally decreased in female mice with low GH levels or action (NeuroDrd2KO and/or aHepGHRkd mice) and increased in HiGH females, while in contrast, Pgc1a was increased in female NeuroDrd2KO but decreased in STAT5bCA and aHepIGF1kd females. Bioinformatic analysis of RNAseq from aHepGHRkd livers stressed the greater impact of GHR loss on wide gene expression in males and highlighted that GH modifies almost completely different gene signatures in each sex. Concordantly, we show that altering different steps of the GH cascade in the liver modified liver expression of Lcn13, Asns, Cyp7b1, Hao2, Hamp2, Pgc1a, Cyp2a4, and Cyp2b9 in a sex- and gene-specific manner.

Perturbation of serum metabolome in relation to type 2 diabetes mellitus and urinary levels of phthalate metabolites and bisphenols

BACKGROUND

Emerging evidence has proved the associations between exposure to phthalates (PAEs) and bisphenols and type 2 diabetes mellitus (T2DM), but the underlying mechanisms for these associations are poorly understood. Metabolomics is a powerful tool to identify differential metabolites and metabolic pathways related to diseases and chemical exposure, which may reveal underlying mechanisms. However, little is known about the roles of metabolism in the associations for PAE and bisphenol exposure with T2DM.

OBJECTIVES

The purpose of the study was to investigate the roles of metabolism in the associations for exposure to PAEs and bisphenols with T2DM.

METHODS

In this study, 60 T2DM cases and 60 controls, who were matched in age, sex, and body mass index (BMI), were selected from the total study population in our previous studies. Fasting blood and spot urine samples of the volunteers were used for non-targeted metabolomics analysis and determination of phthalate metabolites (mPAEs) and bisphenols, respectively. The associations of urinary mPAEs and bisphenols with screened metabolic biomarkers in metabolomics analysis were analyzed using multiple linear regression models.

RESULTS

Based on non-targeted metabolomics, 19 serum metabolic biomarkers were screened between T2DM cases and controls, mostly related to galactose metabolism, amino acid metabolism, and pyrimidine metabolism. More than half of mPAEs were mostly positively associated with up-regulated metabolic biomarkers and negatively associated with down-regulated biomarkers. Different from PAEs, no evident results suggested the roles of metabolism in the associations between bisphenol exposure and T2DM.

CONCLUSIONS

Combined with the positive associations between most urinary mPAEs and T2DM in our previous study, our findings indicated that PAE exposure may contribute to T2DM risk through disturbing galactose metabolism, amino acid metabolism (especially arginine biosynthesis and alanine, aspartate and glutamate metabolism), and pyrimidine metabolism.

Interactive effects of asparagine and aspartate homeostasis with sex and age for the risk of type 2 diabetes risk

BACKGROUND

Asparagine and aspartate homeostasis are linked with type 2 diabetes (T2D). This study aimed to explore whether asparagine and aspartate metabolism interacted with sex and age to increase the risk of T2D.

METHODS

From 27 May 2015 to 3 August 2016, we consecutively retrieved 1032 T2D patients and 1522 subjects without T2D from a tertiary care hospital in Liaoning, China. Restricted cubic spline nested in the logistic regression was used to draw odds ratio curves of plasma asparagine to aspartate ratio for T2D by sex and age. Cut-off point was selected where curves went apart, indicating possible interaction. Addictive interactions of asparagine to aspartate ratio with sex or age and secondary interaction with copresence of unfavorable sex and age were further estimated using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (S).

RESULTS

Ratio of asparagine to aspartate > 1.5 was associated with elevated risk of T2D (OR 7.99, 95%CI 5.50 to 11.6), which was enhanced by female gender to 13.6, (95%CI 8.10-22.9) and by > 50 years of age to 28.7 (14.6-56.3), with significant additive interactions. There was a significant secondary-interaction of copresence of female sex and > 50 years of age with high asparagine to aspartate ratio for increased T2D risk with the OR being further increased to 34.4 (20.5-57.5).

CONCLUSIONS

High asparagine to aspartate ratio was associated with markedly increased risk of T2D, which was further amplified by either female gender or > 50 years of age, and especially both.