Expression Patterns and Correlations with Metabolic Markers of Zinc Transporters <i>ZIP14</i> and <i>ZNT1</i> in Obesity and Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is associated with infertility, increased androgen levels, and insulin resistance. In adipose tissue, zinc facilitates insulin signaling. Circulating zinc levels are altered in obesity, diabetes, and PCOS; and zinc supplementation can ameliorate metabolic disturbances in PCOS. In adipose tissue, expression of zinc influx transporter ZIP14 varies with body mass index (BMI), clinical markers of metabolic syndrome, and peroxisome proliferator-activated receptor gamma (PPARG). In this study, we investigated expression levels of ZIP14 and PPARG in subcutaneous adipose tissue of 36 PCOS women (17 lean and 19 obese women) compared with 23 healthy controls (7 lean and 16 obese women). Further, expression levels of zinc transporter ZIP9, a recently identified androgen receptor, and zinc efflux transporter ZNT1 were investigated, alongside lipid profile and markers of glucose metabolism [insulin degrading enzyme, retinol-binding protein 4 (RBP4), and glucose transporter 4 (GLUT4)]. We find that ZIP14 expression is reduced in obesity and positively correlates with PPARG expression, which is downregulated with increasing BMI. ZNT1 is upregulated in obesity, and both ZIP14 and ZNT1 expression significantly correlates with clinical markers of altered glucose metabolism. In addition, RBP4 and GLUT4 associate with obesity, but an association with PCOS as such was present only for PPARG and RBP4. ZIP14 and ZNT1 does not relate to clinical androgen status and ZIP9 is unaffected by all parameters investigated. In conclusion, our findings support the existence of a zinc dyshomeostasis in adipose tissue in metabolic disturbances including PCOS-related obesity

X chromosome dosage and the genetic impact across human tissues

Abstract Background Sex chromosome aneuploidies (SCAs) give rise to a broad range of phenotypic traits and diseases. Previous studies based on peripheral blood samples have suggested the presence of ripple effects, caused by altered X chromosome number, affecting the methylome and transcriptome. Whether these alterations can be connected to disease-specific tissues, and thereby having clinical implication for the phenotype, remains to be elucidated. Methods We performed a comprehensive analysis of X chromosome number on the transcriptome and methylome in blood, fat, and muscle tissue from individuals with 45,X, 46,XX, 46,XY, and 47,XXY. Results X chromosome number affected the transcriptome and methylome globally across all chromosomes in a tissue-specific manner. Furthermore, 45,X and 47,XXY demonstrated a divergent pattern of gene expression and methylation, with overall gene downregulation and hypomethylation in 45,X and gene upregulation and hypermethylation in 47,XXY. In fat and muscle, a pronounced effect of sex was observed. We identified X chromosomal genes with an expression pattern different from what would be expected based on the number of X and Y chromosomes. Our data also indicate a regulatory function of Y chromosomal genes on X chromosomal genes. Fourteen X chromosomal genes were downregulated in 45,X and upregulated in 47,XXY, respectively, in all three tissues (AKAP17A, CD99, DHRSX, EIF2S3, GTPBP6, JPX, KDM6A, PP2R3B, PUDP, SLC25A6, TSIX, XIST, ZBED1, ZFX). These genes may be central in the epigenetic and genomic regulation of sex chromosome aneuploidies. Conclusion We highlight a tissue-specific and complex effect of X chromosome number on the transcriptome and methylome, elucidating both shared and non-shared gene-regulatory mechanism between SCAs

Regulation of Lipolysis and Adipose Tissue Signaling during Acute Endotoxin-Induced Inflammation: A Human Randomized Crossover Trial

<div><p>Background</p><p>Lipolysis is accelerated during the acute phase of inflammation, a process being regulated by pro-inflammatory cytokines (e.g. TNF-α), stress-hormones, and insulin. The intracellular mechanisms remain elusive and we therefore measured pro- and anti-lipolytic signaling pathways in adipocytes after <i>in vivo</i> endotoxin exposure.</p><p>Methods</p><p>Eight healthy, lean, male subjects were investigated using a randomized cross over trial with two interventions: i) bolus injection of saline (Placebo) and ii) bolus injection of lipopolysaccharide endotoxin (LPS). A ³H-palmitate tracer was used to measure palmitate rate of appearance (<i>Ra</i>_palmitate) and indirect calorimetry was performed to measure energy expenditures and lipid oxidation rates. A subcutaneous abdominal fat biopsy was obtained during both interventions and subjected to western blotting and qPCR quantifications.</p><p>Results</p><p>LPS caused a mean increase in serum free fatty acids (FFA) concentrations of 90% (CI-95%: 37–142, p = 0.005), a median increase in <i>Ra</i>_palmitate of 117% (CI-95%: 77–166, p<0.001), a mean increase in lipid oxidation of 49% (CI-95%: 1–96, p = 0.047), and a median increase in energy expenditure of 28% (CI-95%: 16–42, p = 0.001) compared with Placebo. These effects were associated with increased phosphorylation of hormone sensitive lipase (pHSL) at ser⁶⁵⁰ in adipose tissue (p = 0.03), a trend towards elevated pHSL at ser⁵⁵² (p = 0.09) and cAMP-dependent protein kinase A (PKA) phosphorylation of perilipin 1 (PLIN1) (p = 0.09). Phosphatase and tensin homolog (PTEN) also tended to increase (p = 0.08) while phosphorylation of Akt at Thr³⁰⁸ tended to decrease (p = 0.09) during LPS compared with Placebo. There was no difference between protein or mRNA expression of ATGL, G0S2, and CGI-58.</p><p>Conclusion</p><p>LPS stimulated lipolysis in adipose tissue and is associated with increased pHSL and signs of increased PLIN1 phosphorylation combined with a trend toward decreased insulin signaling. The combination of these mechanisms appear to be the driving forces behind the increased lipolysis observed in the early stages of acute inflammation and sepsis.</p><p>Trial Registration</p><p>ClinicalTrials.gov <a href="https://clinicaltrials.gov/ct2/show/NCT01705782" target="_blank">NCT01705782</a></p></div

Western blot analyses of subcutaneous abdominal fat tissue biopsies.

<p>Representative western blots in abdominal adipose tissue during control conditions (Placebo) and during lipopolysaccharide (LPS) induced endotoxemia (n = 7). Data are presented as the ratio change compared to the median value for the Placebo condition. The black horizontal bars indicate the median value for each group (= 1 for Placebo in all graphs). Paired sample t-test was used to compare groups. <b>A.</b> <i>G0S2 = G0/G1 switch protein 2</i>, <b>B.</b> <i>ATGL = adipose triglyceride lipase</i>, <b>C.</b> <i>CGI-58 = comparative gene identification-58</i>, <b>D.,E.,</b> and <b>F.</b> <i>HSL = hormone sensitive lipase</i>, <i>and</i> <b>G.</b> <i>p-PKA Substrate = Phospho-PKA (protein kinase A) Substrate</i>.</p

qPCR measurements of subcutaneous abdominal fat biopsies.

<p>Quantitative PCR measurements (n = 6) of mRNA are shown for control conditions (Placebo) and during lipopolysaccharide (LPS): <b>A.</b> <i>G0S2 = G0/G1 switch protein 2</i>, <b>B.</b> <i>ATGL = adipose triglyceride lipase</i>, <i>and</i> <b>C.</b> <i>CGI-58 = comparative gene identification-58</i>.</p

Metabolic measures.

<p>Data are shown as dot-plots for each subject during the control conditions with saline administration (Placebo) and the day with lipopolysaccharide administration (LPS). A black horizontal bar indicates the median value for each group. A<b>.</b> Ra_palmitate (n = 8), <b>B.</b> lipid oxidation rates from indirect calorimetry measurements (n = 7), and <b>C.</b> energy expenditure from indirect calorimtry measurements (n = 7). Paired sample t-<i>tests</i> were used to compare groups. <i>Ra</i>_{<i>palmitate</i>} <i>= rate of appearance of palmitate</i>, <i>FFA = free fatty acids</i>.</p

Western blot analyses of subcutaneous abdominal fat tissue biopsies.

<p>Representative western blots in abdominal adipose tissue during control conditions (Placebo) and during lipopolysaccharide (LPS) induced endotoxemia (n = 7). Data are presented as the ratio change compared to the median value for the Placebo condition. The black horizontal bars indicate the median value for each group (= 1 for Placebo in all graphs). Paired sample t-test was used to compare groups. <b>A.</b> <i>PTEN =</i> p<i>hosphatase and tensin homolog</i>, <b>B.</b> and <b>C.</b> <i>Akt</i>, <i>and</i> <b>D.</b> <i>AS160 = Akt substrate of 160 kDa</i>.</p

CONSORT flowchart for the trial.

<p>CONSORT flowchart for the trial.</p

Flowchart showing the time course for the trial days.

<p>At <i>time = 0 min</i> a bolus of isotonic saline (Placebo) or a bolus lipopolysaccharide (LPS) was given.</p