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

Exposure to environmental doses of DEHP causes phenotypes of polycystic ovary syndrome

Globally, approximately 6-20% of women who are of reproductive age suffer from polycystic ovary syndrome (PCOS), with environmental factors believed to be significant contributors. Di-2-ethylhexyl phthalate (DEHP) is known to be an endocrine disruptor, and is also suspected of being associated with the occurrence of PCOS, but in vivo studies to verify this association are lacking. In this study, female SD rats were exposed to DEHP at levels of 0.1, 1.0, and 10mg/kg/d, which are comparable to daily human exposure, to explore its potential role in the development of PCOS. The findings indicated that DEHP exposure reduced ovarian and uterine coefficients, decreased accumulation of primordial follicles, increased the prevalence of atretic and cystic follicles and fibrosis in ovarian tissues, altered serum hormone levels, elevated blood glucose levels and insulin resistance, disrupted the endocrine system and resulted in significant oxidative damage in the ovarian tissues. These results imply that DEHP exposure may cause lesions resembling PCOS to develop. By analyzing the differential expression of the proteome, and using GO and KEGG enrichment analyses, we found they were mainly enriched in the metabolic pathway and in the PPAR signaling pathway. We confirmed that activation of the PPARγ signaling pathway caused by DEHP exposure, is related to the emergence of PCOS-like lesions. This research provides direct in vivo experimental evidence for the association between DEHP exposure and PCOS.

Structural insights into the calcium-coupled zinc export of human ZnT1

Cellular zinc (Zn2+) homeostasis is essential to human health and is under tight regulations. Human zinc transporter 1 (hZnT1) is a plasma membrane-localized Zn2+ exporter belonging to the ZnT family, and its functional aberration is associated with multiple diseases. Here, we show that hZnT1 works as a Zn2+/Ca2+ exchanger. We determine the structure of hZnT1 using cryo-electron microscopy (cryo-EM) single particle analysis. hZnT1 adopts a homodimeric structure, and each subunit contains a transmembrane domain consisting of six transmembrane segments, a cytosolic domain, and an extracellular domain. The transmembrane region displays an outward-facing conformation. On the basis of structural and functional analysis, we propose a model for the hZnT1-mediated Zn2+/Ca2+ exchange. Together, these results facilitate our understanding of the biological functions of hZnT1 and provide a basis for further investigations of the ZnT family transporters.

From zinc homeostasis to disease progression: Unveiling the neurodegenerative puzzle

Zinc is a crucial trace element in the human body, playing a role in various physiological processes such as oxidative stress, neurotransmission, protein synthesis, and DNA repair. The zinc transporters (ZnTs) family members are responsible for exporting intracellular zinc, while Zrt- and Irt-like proteins (ZIPs) are involved in importing extracellular zinc. These processes are essential for maintaining cellular zinc homeostasis. Imbalances in zinc metabolism have been linked to the development of neurodegenerative diseases. Disruptions in zinc levels can impact the survival and activity of neurons, thereby contributing to the progression of neurodegenerative diseases through mechanisms like cell apoptosis regulation, protein phase separation, ferroptosis, oxidative stress, and neuroinflammation. Therefore, conducting a systematic review of the regulatory network of zinc and investigating the relationship between zinc dysmetabolism and neurodegenerative diseases can enhance our understanding of the pathogenesis of these diseases. Additionally, it may offer new insights and approaches for the treatment of neurodegenerative diseases.

Absence of Slc39a14/Zip14 in mouse pancreatic beta cells results in hyperinsulinemia

Zinc is an essential component of the insulin protein complex synthesized in β cells. The intracellular compartmentalization and distribution of zinc are controlled by 24 transmembrane zinc transporters belonging to the ZnT or Zrt/Irt-like protein (ZIP) family. Downregulation of SLC39A14/ZIP14 has been reported in pancreatic islets of patients with type 2 diabetes (T2D) as well as mouse models of high-fat diet (HFD)- or db/db-induced obesity. Our previous studies observed mild hyperinsulinemia in mice with whole body knockout of Slc39a14 (Zip14 KO). Based on our current secondary data analysis from an integrative single-cell RNA-seq dataset of human whole pancreatic tissue, SLC39A14 (coding ZIP14) is the only other zinc transporter expressed abundantly in human β cells besides well-known zinc transporter SLC30A8 (coding ZnT8). In the present work, using pancreatic β cell-specific knockout of Slc39a14 (β-Zip14 KO), we investigated the role of SLC39A14/ZIP14-mediated intracellular zinc trafficking in glucose-stimulated insulin secretion and subsequent metabolic responses. Glucose-stimulated insulin secretion, zinc concentrations, and cellular localization of ZIP14 were assessed using in vivo, ex vivo, and in vitro assays using β-Zip14 KO, isolated islets, and murine cell line MIN6. Metabolic evaluations were done on both chow- and HFD-fed mice using time-domain nuclear magnetic resonance and a comprehensive laboratory animal monitoring system. ZIP14 localizes on the endoplasmic reticulum regulating intracellular zinc trafficking in β cells and serves as a negative regulator of glucose-stimulated insulin secretion. Deletion of Zip14 resulted in greater glucose-stimulated insulin secretion, increased energy expenditure, and shifted energy metabolism toward fatty acid utilization. HFD caused β-Zip14 KO mice to develop greater islet hyperplasia, compensatory hyperinsulinemia, and mild insulin resistance and hyperglycemia. This study provided new insights into the contribution of metal transporter ZIP14-mediated intracellular zinc trafficking in glucose-stimulated insulin secretion and subsequent metabolic responses.NEW & NOTEWORTHY Metal transporter SLC39A14/ZIP14 is downregulated in pancreatic islets of patients with T2D and mouse models of HFD- or db/db-induced obesity. However, the function of ZIP14-mediated intracellular zinc trafficking in β cells is unknown. Our analyses revealed that SLC39A14 is the only Zn transporter expressed abundantly in human β cells besides SLC30A8. Within the β cells, ZIP14 is localized on the endoplasmic reticulum and serves as a negative regulator of insulin secretion, providing a potential therapeutic target for T2D.

The Role of Peroxisome Proliferator-Activated Receptors in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) constitutes the most common endocrine disorder in women of reproductive age. Patients usually suffer from severe menstrual irregularities, skin conditions, and insulin resistance-associated health conditions. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor proteins that regulate gene expression. In order to investigate the role of PPARs in the pathophysiology of PCOS, we conducted a literature review using the MEDLINE and LIVIVO databases and were able to identify 74 relevant studies published between 2003 and 2023. Different study groups reached contradictory conclusions in terms of PPAR expression in PCOS. Interestingly, numerous natural agents were found to represent a novel, potent anti-PCOS treatment alternatives. In conclusion, PPARs seem to play a significant role in PCOS.

Total plasma magnesium, zinc, copper and selenium concentrations in obese patients before and after bariatric surgery

Obesity enhances the risk of type-2 diabetes, cardiovascular disease and inflammatory conditions and often leads to metal dyshomeostasis, which contributes to the negative health aspects associated with the disease. In severe cases, bariatric surgery can be recommended to achieve sustained weight loss and improvement in health. Here, magnesium, zinc, copper and selenium concentrations were examined in 24 obese patients (7 males; 17 females) before and 9 months after undergoing Roux-en-Y gastric bypass surgery. All patients lost weight over this period, with the mean BMI reducing from 51.2±7.1 kg/m2 to 37.2±5.5 kg/m2. Moreover, whole-blood glycated haemoglobin (HbA1c), as a marker of average glycaemia, was also measured and a correlative analysis of this parameter with metal concentrations performed. Significant alterations in the plasma concentrations of magnesium, zinc (both increased by 13.2% and 25.2% respectively) and copper (decreased by 7.9%) were observed over this period (plasma selenium concentration was unchanged), with BMI values correlating with plasma magnesium (p = 0.004) and zinc (p = 0.022) concentrations. At 9 months post-surgery, an increase in mean zinc/copper ratio was observed (0.86±0.29 compared to 0.63±0.14 pre-surgery). Comparison of whole-blood HbA1c concentrations pre- and post-surgery revealed a reduction from 6.50±1.28% pre-surgery to 5.51±0.49% post-surgery. Differences in plasma HbA1c and magnesium at either pre- and post-surgery correlated significantly, as did HbA1c and magnesium levels when pre- and post-surgery values were analysed together. Collectively, this work reveals that bariatric surgery, in conjunction with lifestyle/dietary changes, lead to improvements in the nutritional status of magnesium, zinc and copper. Furthermore, the observed improvements in magnesium and zinc were associated with weight loss and in the case of magnesium, to better glycaemic control.

Molecular characterization of extracellular vesicles derived from follicular fluid of women with and without PCOS: integrating analysis of differential miRNAs and proteins reveals vital molecules involving in PCOS

PURPOSE

To elucidate the characterization of extracellular vesicles (EVs) in the follicular fluid-derived extracellular vesicles (FF-EVs) and discover critical molecules and signaling pathways associating with the etiology and pathobiology of PCOS, the differentially expressed miRNAs (DEmiRNAs) and differentially expressed proteins profiles (DEPs) were initially explored and combinedly analyzed.

METHODS

First, the miRNA and protein expression profiles of FF-EVs in PCOS patients and control patients were compared by RNA-sequencing and tandem mass tagging (TMT) proteomic methods. Subsequently, Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes were used to analyze the biological function of target genes of DEmiRNAs and DEPs. Finally, to discover the functional miRNA-target gene-protein interaction pairs involved in PCOS, DEmiRs target gene datasets and DEPs datasets were used integratedly.

RESULTS

A total of 6 DEmiRNAs and 32 DEPs were identified in FF-EVs in patients with PCOS. Bioinformatics analysis revealed that DEmiRNAs target genes are mainly involved in thiamine metabolism, insulin secretion, GnRH, and Apelin signaling pathway, which are closely related to the occurrence of PCOS. DEPs also closely related to hormone metabolism processes such as steroid hormone biosynthesis. In the analysis integrating DEmiRNAs target genes and DEPs, two molecules, GRAMD1B and STPLC2, attracted our attention that are closely associated with cholesterol transport and ceramide biosynthesis, respectively.

CONCLUSION

Dysregulated miRNAs and proteins in FF-EVs, mainly involving in hormone metabolism, insulin secretion, neurotransmitters regulation, adipokine expression, and secretion, may be closely related to PCOS. The effects of GRAMD1B and STPLC2 on PCOS deserve further study.

Anti-inflammatory mechanisms of polyphenols in adipose tissue: role of gut microbiota, intestinal barrier integrity and zinc homeostasis

Obesity is associated with an imbalance of micro-and macro-nutrients, gut dysbiosis, and a "leaky" gut phenomenon. Polyphenols, such as curcumin, resveratrol, and anthocyanins may alleviate the systemic effects of obesity, potentially by improving gut microbiota, intestinal barrier integrity (IBI), and zinc homeostasis. The essential micronutrient zinc plays a crucial role in the regulation of enzymatic processes, including inflammation, maintenance of the microbial ecology, and intestinal barrier integrity. In this review, we focus on IBI- which prevents intestinal lipopolysaccharide (LPS) leakage - as a critical player in polyphenol-mediated protective effects against obesity-associated white adipose tissue (WAT) inflammation. This occurs through mechanisms that block the movement of the bacterial endotoxin LPS across the gut barrier. Available research suggests that polyphenols reduce WAT and systemic inflammation via crosstalk with inflammatory NF-κB, the mammalian target of rapamycin (mTOR) signaling and zinc homeostasis.

Zinc transporter ZIP12 maintains zinc homeostasis and protects spermatogonia from oxidative stress during spermatogenesis

BACKGROUND

Overwhelming evidences suggest oxidative stress is a major cause of sperm dysfunction and male infertility. Zinc is an important non-enzymatic antioxidant with a wide range of biological functions and plays a significant role in preserving male fertility. Notably, zinc trafficking through the cellular and intracellular membrane is mediated by specific families of zinc transporters, i.e., SLC39s/ZIPs and SLC30s/ZnTs. However, their expression and function were rarely evaluated in the male germ cells. The aim of this study is to determine and characterize the crucial zinc transporter responsible for the maintenance of spermatogenesis.

METHODS

The expression patterns of all 14 ZIP members were characterized in the mouse testis. qRT-PCR, immunoblot and immunohistochemistry analyses evaluated the ZIP12 gene and protein expression levels. The role of ZIP12 expression was evaluated in suppressing the sperm quality induced by exposure to an oxidative stress in a spermatogonia C18-4 cell line. Zip12 RNAi transfection was performed to determine if its downregulation altered cell viability and apoptosis in this cell line. An obese mouse model fed a high-fat-diet was employed to determine if there is a correlation between changes in the ZIP12 expression level and sperm quality.

RESULTS

The ZIP12 mRNA and protein expression levels were higher than those of other ZIP family members in both the mouse testis and other tissues. Importantly, the ZIP12 expression levels were very significantly higher in both mice and human spermatogonia and spermatozoa. Moreover, the testicular ZIP12 expression levels significantly decreased in obese mice, which was associated with reduced sperm zinc content, excessive sperm ROS generation, poor sperm quality and male subfertility. Similarly, exposure to an oxidative stress induced significant declines in the ZIP12 expression level in C18-4 cells. Knockdown of ZIP12 expression mediated by transfection of a ZIP12 siRNA reduced both the zinc content and viability whereas apoptotic activity increased in the C18-4 cell line.

CONCLUSIONS

The testicular zinc transporter ZIP12 expression levels especially in spermatogonia and spermatozoa are higher than in other tissues. ZIP12 may play a key role in maintaining intracellular zinc content at levels that reduce the inhibitory effects of rises in oxidative stress on spermatogonia and spermatozoa viability during spermatogenesis which help counteract declines in male fertility.

Nutrition Strategy and Life Style in Polycystic Ovary Syndrome-Narrative Review

Here we present an extensive narrative review of the broadly understood modifications to the lifestyles of women with polycystic ovary syndrome (PCOS). The PubMed database was analyzed, combining PCOS entries with causes, diseases, diet supplementation, lifestyle, physical activity, and use of herbs. The metabolic pathways leading to disturbances in lipid, carbohydrate, and hormonal metabolism in targeted patients are described. The article refers to sleep disorders, changes in mental health parameters, and causes of oxidative stress and inflammation. These conditions consistently lead to the occurrence of severe diseases in patients suffering from diabetes, the fatty degeneration of internal organs, infertility, atherosclerosis, cardiovascular diseases, dysbiosis, and cancer. The modification of lifestyles, diet patterns and proper selection of nutrients, pharmacological and natural supplementation in the form of herbs, and physical activity have been proposed. The progress and consequences of PCOS are largely modifiable and depend on the patient’s approach, although we have to take into account also the genetic determinants.

Zinc

Since the discovery of manifest Zn deficiency in 1961, the increasing number of studies demonstrated the association between altered Zn status and multiple diseases. In this chapter, we provide a review of the most recent advances on the role of Zn in health and disease (2010-20), with a special focus on the role of Zn in neurodegenerative and neurodevelopmental disorders, diabetes and obesity, male and female reproduction, as well as COVID-19. In parallel with the revealed tight association between ASD risk and severity and Zn status, the particular mechanisms linking Zn2+ and ASD pathogenesis like modulation of synaptic plasticity through ProSAP/Shank scaffold, neurotransmitter metabolism, and gut microbiota, have been elucidated. The increasing body of data indicate the potential involvement of Zn2+ metabolism in neurodegeneration. Systemic Zn levels in Alzheimer's and Parkinson's disease were found to be reduced, whereas its sequestration in brain may result in modulation of amyloid β and α-synuclein processing with subsequent toxic effects. Zn2+ was shown to possess adipotropic effects through the role of zinc transporters, zinc finger proteins, and Zn-α2-glycoprotein in adipose tissue physiology, underlying its particular role in pathogenesis of obesity and diabetes mellitus type 2. Recent findings also contribute to further understanding of the role of Zn2+ in spermatogenesis and sperm functioning, as well as oocyte development and fertilization. Finally, Zn2+ was shown to be the potential adjuvant therapy in management of novel coronavirus infection (COVID-19), underlining the perspectives of zinc in management of old and new threats.

Deciphering biomarkers of endometriosis by proteomic analysis of eutopic endometrium in infertile patients

AIM

Endometriosis is associated with infertility. The aim of this study was to examine the overall proteomic changes of eutopic endometrium in infertile women with endometriosis.

METHODS

Tandem mass tags combined with multidimensional liquid chromatography and mass spectrometry analyses were used to screen the proteomic profiles of eutopic endometrium from infertile patients with endometriosis (N = 4), compared with that from patients without endometriosis (N = 4). Quantitative proteomic analysis, functional categories and significant pathway analysis were investigated subsequently.

RESULTS

In total, 6.698 proteins were identified, among which 5,812 proteins were quantified. Compared with controls, proteomic analysis showed some differentially expressed proteins: 16 up-regulated proteins and 23 down-regulated proteins. Bioinformatics analysis indicated that differentially expressed proteins were involved in humoral immune response pathways, antimicrobial humoral response and regulation of nitric oxide biosynthetic process. Besides, our results showed that alpha-1-acid glycoprotein 2, complement factor B and zinc transporter Zip14 were important resources for investigating potential mechanism of infertility in infertile women with endometriosis.

CONCLUSIONS

This study provided a reference proteome map of eutopic endometrium from infertile women with endometriosis. The long-term benefits of using those markers to stratify clinical treatment warrant further investigation.

Association of serum levels of vascular endothelial growth factor and thrombospondin-1 to body mass index in polycystic ovary syndrome: a case-control study

Purpose

Polycystic ovary syndrome (PCOS) is a gynecological endocrine disorder that is characterized by disturbances in ovarian blood flow and angiogenesis. The aim of this study was to determine the association of vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1) serum levels with the body mass index (BMI) in patients with PCOS compared with healthy subjects.

Methods

The study was conducted with 80 subjects in 3 PCOS groups, including normal weight, overweight, and obese PCOS groups, and a control group of healthy subjects (n=20). The participants in all groups completed a questionnaire comprising sociodemographic and obstetric questions. The PCOS diagnosis in the study subjects was confirmed based on the Rotterdam criteria, BMI was determined according to the World Health Organization guidelines, and the lipid accumulation product index was calculated for all groups. Venous blood samples were collected from all participants after fasting to measure the serum levels of fasting blood glucose (FBG), lipids, insulin, VEGF, TSP-1, and leptin.

Results

Our findings showed that the serum VEGF level was significantly higher in the normal BMI PCOS group than that in the control group (P=0.03), and the TSP-1 level was significantly lower in the obese PCOS group than that in the control group (P=0.04).

Conclusions

Our study demonstrated that alterations in VEGF and TSP-1 concentrations are dependent on BMI. Because abnormal ovarian angiogenesis is considered to be the main feature of PCOS, the study of ovarian angiogenic imbalance is proposed as a new tool for PCOS diagnosis and management.