Zinc finger protein 407 (ZFP407) regulates insulin-stimulated glucose uptake and glucose transporter 4 (Glut4) mRNA

Association Between Zinc Status and Insulin Resistance/Sensitivity Check Indexes in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is considered the most common metabolic disorder of the pregnancy period. It is characterized by pancreatic beta-cell dysfunction in the setting of chronic insulin resistance. Zinc is a nutrient involved in numerous metabolic processes and shows a relationship with glycometabolic disorders and GDM. The latest data have demonstrated the association of zinc with insulin sensitivity and resistance. The exact role of zinc in the connection with indexes of insulin resistance and insulin sensitivity is still not fully clarified. The aim of the study is to analyze the newly calculated indexes Glu/Zn, Ins/Zn, and HOMA-IR/Zn as surrogate markers to explore the correlation between serum zinc status and some indexes of insulin sensitivity and insulin resistance. The possible role of these indexes as markers of insulin resistance in pregnant women was analyzed too. An ROC analysis demonstrated that HOMA-IR/Zn with AUC 0.989, p < 0.001 (95% CI 0.967-1.000) and Ins/Zn with AUC 0.947, p < 0.001 (95% CI 0.889-1.000) in the GDM group, and only HOMA-IR/Zn index with AUC 0.953, p < 0.001 (95% CI 0.877-1.000) in healthy pregnant women, have good power as markers of insulin resistance in both groups. We speculate that these new ratios could be suitable for the assessment of pregnant women at high risk of insulin resistance development and, probably, for the evaluation of the specific pathophysiologic characteristics of women with GDM.

Cell-state-dependent regulation of PPARγ signaling by the transcription factor ZBTB9 in adipocytes

Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear hormone receptor that is a master regulator of adipocyte differentiation and function. ZBTB9 is a widely expressed but poorly studied transcription factor that was predicted to interact with PPARγ based on large-scale protein-protein interaction experiments. In addition, genome-wide association studies (GWAS) revealed associations between ZBTB9 and BMI, T2D risk, and HbA1c levels. Here we show that Zbtb9 deficiency in mature adipocytes decreased PPARγ activity and protein level, and thus acts as a positive regulator of PPARγ signaling. In contrast, Zbtb9 deficiency in 3T3-L1 and human preadipocytes increased PPARγ levels and enhanced adipogenesis. Transcriptomic and transcription factor binding site analyses of Zbtb9 deficient preadipocytes revealed that the E2F pathway, controlled by the E2F family of transcription factors that are classically associated with cell cycle regulation, was among the most upregulated pathways. E2F1 positively regulates adipogenesis by promoting Pparg expression, independent of its cell cycle role, via direct binding to the Pparg promoter early during adipogenesis. RB phosphorylation (pRB), which regulates E2F activity, was also upregulated in Zbtb9 deficient preadipocytes. Critically, an E2F1 inhibitor blocked the effects of Zbtb9 deficiency on adipogenesis. Collectively, these results demonstrate that Zbtb9 inhibits adipogenesis as a negative regulator of Pparg expression via pRB-E2F signaling. Our findings reveal cell-state dependent roles of ZBTB9 in adipocytes, identifying a new molecule that regulates adipocyte biology as both a positive and negative regulator of PPARγ signaling depending on the cellular context, and thus may be important in the pathogenesis of obesity and T2D.

Deciphering adipose development: Function, differentiation and regulation

The overdevelopment of adipose tissues, accompanied by excess lipid accumulation and energy storage, leads to adipose deposition and obesity. With the increasing incidence of obesity in recent years, obesity is becoming a major risk factor for human health, causing various relevant diseases (including hypertension, diabetes, osteoarthritis and cancers). Therefore, it is of significance to antagonize obesity to reduce the risk of obesity-related diseases. Excess lipid accumulation in adipose tissues is mediated by adipocyte hypertrophy (expansion of pre-existing adipocytes) or hyperplasia (increase of newly-formed adipocytes). It is necessary to prevent excessive accumulation of adipose tissues by controlling adipose development. Adipogenesis is exquisitely regulated by many factors in vivo and in vitro, including hormones, cytokines, gender and dietary components. The present review has concluded a comprehensive understanding of adipose development including its origin, classification, distribution, function, differentiation and molecular mechanisms underlying adipogenesis, which may provide potential therapeutic strategies for harnessing obesity without impairing adipose tissue function.

Molecular regulation of PPARγ/RXRα signaling by the novel cofactor ZFP407

Cofactors interacting with PPARγ can regulate adipogenesis and adipocyte metabolism by modulating the transcriptional activity and selectivity of PPARγ signaling. ZFP407 was previously demonstrated to regulate PPARγ target genes such as GLUT4, and its overexpression improved glucose homeostasis in mice. Here, using a series of molecular assays, including protein-interaction studies, mutagenesis, and ChIP-seq, ZFP407 was found to interact with the PPARγ/RXRα protein complex in the nucleus of adipocytes. Consistent with this observation, ZFP407 ChIP-seq peaks significantly overlapped with PPARγ ChIP-seq peaks, with more than half of ZFP407 peaks overlapping with PPARγ peaks. Transcription factor binding motifs enriched in these overlapping sites included CTCF, RARα/RXRγ, TP73, and ELK1, which regulate cellular development and function within adipocytes. Site-directed mutagenesis of frequent PPARγ phosphorylation or SUMOylation sites did not prevent its regulation by ZFP407, while mutagenesis of ZFP407 domains potentially necessary for RXR and PPARγ binding abrogated any impact of ZFP407 on PPARγ activity. These data suggest that ZFP407 controls the activity of PPARγ, but does so independently of post-translational modifications, likely by direct binding, establishing ZFP407 as a newly identified PPARγ cofactor. In addition, ZFP407 ChIP-seq analyses identified regions that did not overlap with PPARγ peaks. These non-overlapping peaks were significantly enriched for the transcription factor binding motifs of TBX19, PAX8, HSF4, and ZKSCAN3, which may contribute to the PPARγ-independent functions of ZFP407 in adipocytes and other cell types.

Cell-state dependent regulation of PPAR γ signaling by ZBTB9 in adipocytes

Adipocytes play a critical role in metabolic homeostasis. Peroxisome proliferator-activated receptor- γ (PPAR γ ) is a nuclear hormone receptor that is a master regulator of adipocyte differentiation and function. ZBTB9 was predicted to interact with PPAR γ based on large-scale protein interaction experiments. In addition, GWAS studies in the type 2 diabetes (T2D) Knowledge Portal revealed associations between Z btb9 and both BMI and T2D risk. Here we show that ZBTB9 positively regulates PPAR γ activity in mature adipocytes. Surprisingly Z btb9 knockdown (KD) also increased adipogenesis in 3T3-L1 cells and human preadipocytes. E2F activity was increased and E2F downstream target genes were upregulated in Zbtb9 -KD preadipocytes. Accordingly, RB phosphorylation, which regulates E2F activity, was enhanced in Zbtb9 -KD preadipocytes. Critically, an E2F1 inhibitor blocked the effects of Zbtb9 deficiency on adipogenic gene expression and lipid accumulation. Collectively, these results demonstrate that Zbtb9 inhibits adipogenesis as a negative regulator of Pparg expression via altered RB-E2F1 signaling. Our findings reveal complex cell-state dependent roles of ZBTB9 in adipocytes, identifying a new molecule that regulates adipogenesis and adipocyte biology as both a positive and negative regulator of PPAR γ signaling depending on the cellular context, and thus may be important in the pathogenesis and treatment of obesity and T2D.

Diabetic cardiomyopathy - Zinc preventive and therapeutic potentials by its anti-oxidative stress and sensitizing insulin signaling pathways

Oxidative stress and insulin resistance are two key mechanisms for the development of diabetic cardiomyopathy (DCM, cardiac remodeling and dysfunction). In this review, we discussed how zinc and metallothionein (MT) protect the heart from type 1 or type 2 diabetes (T1D or T2D) through its anti-oxidative function and insulin-mediated PI3K/Akt signaling activation. Both T1D and T2D-induced DCM, shown by cardiac structural remodeling and dysfunction, in wild-type mice, but not in cardiomyocyte-specific overexpressing MT mice. In contrast, mice with global MT gene deletion were more susceptible to the development of DCM. When we used zinc to treat mice with either T1D or T2D, cardiac remodeling and dysfunction were significantly prevented along with increased cardiac MT expression. To support the role of zinc homeostasis in insulin signaling pathways, treatment of diabetic mice with zinc showed the preservation of phosphorylation levels of insulin-mediated glucose metabolism-related Akt2 and GSK-3β and even rescued cardiac pathogenesis induced by global deletion of Akt2 gene in a MT-dependent manner. These results suggest the protection by zinc from DCM is through both the induction of MT and sensitization of insulin signaling. Combined our own and other works, this review comprehensively summarized the roles of zinc homeostasis in the development and progression of DCM and its therapeutic implications. At the end, we provided pre-clinical and clinical evidence for the preventive and therapeutic potential of zinc supplementation through its anti-oxidative stress and sensitizing insulin signaling actions. Understanding the intricate connections between zinc and DCM provides insights for the future interventional approaches.

Effects of stressful life-events on DNA methylation in panic disorder and major depressive disorder

BACKGROUND

Panic disorder (PD) is characterized by recurrent panic attacks and higher affection of women as compared to men. The lifetime prevalence of PD is about 2-3% in the general population leading to tremendous distress and disability. Etiologically, genetic and environmental factors, such as stress, contribute to the onset and relapse of PD. In the present study, we investigated epigenome-wide DNA methylation (DNAm) in respond to a cumulative, stress-weighted life events score (wLE) in patients with PD and its boundary to major depressive disorder (MDD), frequently co-occurring with symptoms of PD.

METHODS

DNAm was assessed by the Illumina HumanMethylation450 BeadChip. In a meta-analytic approach, epigenome-wide DNAm changes in association with wLE were first analyzed in two PD cohorts (with a total sample size of 183 PD patients and 85 healthy controls) and lastly in 102 patients with MDD to identify possible overlapping and opposing effects of wLE on DNAm. Additionally, analysis of differentially methylated regions (DMRs) was conducted to identify regional clusters of association.

RESULTS

Two CpG-sites presented with p-values below 1 × 10-05 in PD: cg09738429 (p = 6.40 × 10-06, located in an intergenic shore region in next proximity of PYROXD1) and cg03341655 (p = 8.14 × 10-06, located in the exonic region of GFOD2). The association of DNAm at cg03341655 and wLE could be replicated in the independent MDD case sample indicating a diagnosis independent effect. Genes mapping to the top hits were significantly upregulated in brain and top hits have been implicated in the metabolic system. Additionally, two significant DMRs were identified for PD only on chromosome 10 and 18, including CpG-sites which have been reported to be associated with anxiety and other psychiatric phenotypes.

CONCLUSION

This first DNAm analysis in PD reveals first evidence of small but significant DNAm changes in PD in association with cumulative stress-weighted life events. Most of the top associated CpG-sites are located in genes implicated in metabolic processes supporting the hypothesis that environmental stress contributes to health damaging changes by affecting a broad spectrum of systems in the body.

Hierarchical regulation of autophagy during adipocyte differentiation

We previously showed that some adipogenic transcription factors such as CEBPB and PPARG directly and indirectly regulate autophagy gene expression in adipogenesis. The order and effect of these events are undetermined. In this study, we modeled the gene expression, DNA-binding of transcriptional regulators, and histone modifications during adipocyte differentiation and evaluated the effect of the regulators on gene expression in terms of direction and magnitude. Then, we identified the overlap of the transcription factors and co-factors binding sites and targets. Finally, we built a chromatin state model based on the histone marks and studied their relation to the factors’ binding. Adipogenic factors differentially regulated autophagy genes as part of the differentiation program. Co-regulators associated with specific transcription factors and preceded them to the regulatory regions. Transcription factors differed in the binding time and location, and their effect on expression was either localized or long-lasting. Adipogenic factors disproportionately targeted genes coding for autophagy-specific transcription factors. In sum, a hierarchical arrangement between adipogenic transcription factors and co-factors drives the regulation of autophagy during adipocyte differentiation.

The metabolic signaling of the nucleoredoxin-like 2 gene supports brain function

The nucleoredoxin gene NXNL2 encodes for two products through alternative splicing, rod-derived cone viability factor-2 (RdCVF2) that mediates neuronal survival and the thioredoxin-related protein (RdCVF2L), an enzyme that regulates the phosphorylation of TAU. To investigate the link between NXNL2 and tauopathies, we studied the Nxnl2 knockout mouse (Nxnl2-/-). We established the expression pattern of the Nxnl2 gene in the brain using a Nxnl2 reporter mouse line, and characterized the behavior of the Nxnl2-/- mouse at 2 months of age. Additionally, long term potentiation and metabolomic from hippocampal specimens were collected at 2 months of age. We studied TAU oligomerization, phosphorylation and aggregation in Nxnl2-/- brain at 18 months of age. Finally, newborn Nxnl2-/- mice were treated with adeno-associated viral vectors encoding for RdCVF2, RdCVF2L or both and measured the effect of this therapy on long-term potential, glucose metabolism and late-onset tauopathy. Nxnl2-/- mice at 2 months of age showed severe behavioral deficiency in fear, pain sensitivity, coordination, learning and memory. The Nxnl2-/- also showed deficits in long-term potentiation, demonstrating that the Nxnl2 gene is involved in regulating brain functions. Dual delivery of RdCVF2 and RdCVF2L in newborn Nxnl2-/- mice fully correct long-term potentiation through their synergistic action. The expression pattern of the Nxnl2 gene in the brain shows a predominant expression in circumventricular organs, such as the area postrema. Glucose metabolism of the hippocampus of Nxnl2-/- mice at 2 months of age was reduced, and was not corrected by gene therapy. At 18-month-old Nxnl2-/- mice showed brain stigmas of tauopathy, such as oligomerization, phosphorylation and aggregation of TAU. This late-onset tauopathy can be prevented, albeit with modest efficacy, by recombinant AAVs administrated to newborn mice. The Nxnl2-/- mice have memory dysfunction at 2-months that resembles mild-cognitive impairment and at 18-months exhibit tauopathy, resembling to the progression of Alzheimer's disease. We propose the Nxnl2-/- mouse is a model to study multistage aged related neurodegenerative diseases. The NXNL2 metabolic and redox signaling is a new area of therapeutic research in neurodegenerative diseases.

A Small Fraction of Progenitors Differentiate Into Mature Adipocytes by Escaping the Constraints on the Cell Structure

Differentiating 3T3-L1 pre-adipocytes are a mixture of non-identical culture cells. It is vital to identify the cell types that respond to the induction stimulus to understand the pre-adipocyte potential and the mature adipocyte behavior. To test this hypothesis, we deconvoluted the gene expression profiles of the cell culture of MDI-induced 3T3-L1 cells. Then we estimated the fractions of the sub-populations and their changes in time. We characterized the sub-populations based on their specific expression profiles. Initial cell cultures comprised three distinct phenotypes. A small fraction of the starting cells responded to the induction and developed into mature adipocytes. Unresponsive cells were probably under structural constraints or were committed to differentiating into alternative phenotypes. Using the same population gene markers, similar proportions were found in induced human primary adipocyte cell cultures. The three sub-populations had diverse responses to treatment with various drugs and compounds. Only the response of the maturating sub-population resembled that estimated from the profiles of the mixture. We then showed that even at a low division rate, a small fraction of cells could increase its share in a dynamic two-populations model. Finally, we used a cell cycle expression index to validate that model. To sum, pre-adipocytes are a mixture of different cells of which a limited fraction become mature adipocytes.

Partial Deficiency of Zfp217 Resists High-Fat Diet-Induced Obesity by Increasing Energy Metabolism in Mice

Obesity-induced adipose tissue dysfunction and disorders of glycolipid metabolism have become a worldwide research priority. Zfp217 plays a crucial role in adipogenesis of 3T3-L1 preadipocytes, but about its functions in animal models are not yet clear. To explore the role of Zfp217 in high-fat diet (HFD)-induced obese mice, global Zfp217 heterozygous knockout (Zfp217^+/−) mice were constructed. Zfp217^+/− mice and Zfp217^+/+ mice fed a normal chow diet (NC) did not differ significantly in weight gain, percent body fat mass, glucose tolerance, or insulin sensitivity. When challenged with HFD, Zfp217^+/− mice had less weight gain than Zfp217^+/+ mice. Histological observations revealed that Zfp217^+/− mice fed a high-fat diet had much smaller white adipocytes in inguinal white adipose tissue (iWAT). Zfp217^+/− mice had improved metabolic profiles, including improved glucose tolerance, enhanced insulin sensitivity, and increased energy expenditure compared to the Zfp217^+/+ mice under HFD. We found that adipogenesis-related genes were increased and metabolic thermogenesis-related genes were decreased in the iWAT of HFD-fed Zfp217^+/+ mice compared to Zfp217^+/− mice. In addition, adipogenesis was markedly reduced in mouse embryonic fibroblasts (MEFs) from Zfp217-deleted mice. Together, these data indicate that Zfp217 is a regulator of energy metabolism and it is likely to provide novel insight into treatment for obesity.

Adipocyte-specific deletion of zinc finger protein 407 results in lipodystrophy and insulin resistance in mice

PPARγ deficiency in humans and model organisms impairs the transcriptional control of adipogenesis and mature adipocyte function resulting in lipodystrophy and insulin resistance. Zinc finger protein 407 (ZFP407) positively regulates PPARγ target gene expression and insulin-stimulated glucose uptake in cultured adipocytes. The in vivo physiological role of ZFP407 in mature adipocytes, however, remains to be elucidated. Here we generated adipocyte-specific ZFP407 knockout (AZKO) mice and discovered a partial lipodystrophic phenotype with reduced fat mass, hypertrophic adipocytes in inguinal and brown adipose tissue, and reduced adipogenic gene expression. The lipodystrophy was further exacerbated in AZKO mice fed a high-fat diet. Glucose and insulin tolerance tests revealed decreased insulin sensitivity in AZKO mice compared to control littermates. Cell-based assays demonstrated that ZFP407 is also required for adipogenesis, which may also contribute to the lipodystrophic phenotype. These results demonstrate an essential in vivo role of ZFP407 in brown and white adipose tissue formation and organismal insulin sensitivity.

Alternative Splicing and Cleavage of GLUT8

The GLUT (SLC2) family of membrane-associated transporters are described as glucose transporters. However, this family is divided into three classes and, though the regulated transporter activity of class I proteins is becoming better understood, class III protein functions continue to be obscure. We have cataloged the relative expression and splicing of SLC2 mRNA isomers in tumors and normal tissues, with a focus on breast tumors and cell lines. mRNA for the class III protein GLUT8 is the predominant SLC2 species expressed alongside GLUT1 in many tissues, but GLUT8 mRNA exists mostly as an untranslated splice form in tumors. We confirm that GLUT8 is not presented at the cell surface and does not transport glucose directly. However, we reveal a lysosome-dependent reaction that cleaves the GLUT8 protein and releases the carboxy-terminal peptide to a separate vesicle population. Given the localization of GLUT8 at a major metabolic hub (the late endosomal/lysosomal interface) and its regulated cleavage reaction, we evaluated TXNIP-mediated hexosamine homeostasis and speculate that GLUT8 may function as a sensory component of this reaction.

Biallelic ZNF407 mutations in a neurodevelopmental disorder with ID, short stature and variable microcephaly, hypotonia, ocular anomalies and facial dysmorphism

We describe five members of a consanguineous Pakistani family (Family I) plus two affected children from families of different ethnic origins presenting with neurodevelopmental disorders with overlapping features. All affected individuals from families have intellectual disability (ID), ranging from mild to profound, and reduced motor and cognitive skills plus variable features including short stature, microcephaly, developmental delay, hypotonia, dysarthria, deafness, visual problems, enuresis, encopresis, behavioural anomalies, delayed pubertal onset and facial dysmorphism. We first mapped the disease locus in the large family (Family I), and by exome sequencing identified homozygous ZNF407 c.2814_2816dup (p.Val939dup) in four affected members where DNA samples were available. By exome sequencing we detected homozygous c.2405G>T (p.Gly802Val) in the affected member of Family II and compound heterozygous variants c.2884C>G (p.Arg962Gly) and c.3642G>C (p.Lys1214Asn) in the affected member of Family III. Homozygous c.5054C>G (p.Ser1685Trp) has been reported in two brothers with an ID syndrome. Affected individuals we present did not exhibit synophrys, midface hypoplasia, kyphosis, 5th finger camptodactyly, short 4th metatarsals or limited knee mobility observed in the reported family.

The Furan Fatty Acid 9M5 Acts as a Partial Ligand to Peroxisome Proliferator-Activated Receptor gamma and Enhances Adipogenesis in 3T3-L1 Preadipocytes

A food that has been praised for its beneficial effects on overall health is fish, particularly its polyunsaturated n-3 fatty acids, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). However, it has recently been suggested that minor fatty acids such as furan fatty acids are needed in combination with DHA and EPA to exert these positive effects of fish and fish oils. Only recently have furan fatty acids become available in quantities that allow the investigation of their biofunctional properties. In this study, the uptake and effect of the furan fatty acid 9-(3-methyl-5-pentylfuran-2-yl)-nonanoic acid (9M5) as a sole component and in combination with DHA and EPA on adipogenesis were analyzed using the 3T3-L1 cell model. 9M5 is taken up and metabolized into 7M5, 5M5, and 3M5 in 3T3-L1 adipocytes during a 24-h period as shown with gas chromatography with mass spectrometry (GC/MS). Furthermore, 9M5 significantly increased lipid accumulation during the differentiation process of 3T3-L1 preadipocytes into adipocytes. In addition, the combinations of DHA + 9M5 and EPA + DHA + 9M5 also exerted a significant increase compared to control adipocytes. 3T3-L1 cells incubated with 9M5 resulted in an increased protein expression of PPARγ, C/EBPα, FABP4, and adiponectin, although not to the extent that DHA as a sole component or DHA + 9M5 did. Earlier studies have shown that DHA is a natural ligand for PPARγ, thus being a potential alternative to the antidiabetic thiazolidinediones. We show that 9M5 activates a PPARγ-responsive reporter gene and could therefore be a natural ligand for PPARγ.

Modelling the gene expression and the DNA-binding in the 3T3-L1 differentiating adipocytes

The 3T3-L1 pre-adipocyte cell line is widely used to study the fat cell differentiation in vitro. Researchers also use this cell model to study obesity and insulin resistance. We surveyed the literature, the gene expression omnibus and the sequence read archive for RNA-Seq and ChIP-Seq datasets of MDI-induced 3T3-L1 differentiating cells sampled at one or more time points. The metadata of the relevant datasets were manually curated using unified language across the original studies. The raw reads were collected and pre-processed using a reproducible state-of-the-art pipeline. The final datasets are presented as reads count in genes for the RNA-Seq and reads count in peaks for the ChIP-Seq dataset. The curated datasets are available as two Bioconductor experimental data packages curatedAdipoRNA and curatedAdipoChIP. In addition, the packages document the source code of the data collection and the pre-processing pipelines. Here, we provide a descriptive analysis of the datasets with context and technical validation.

Association Between Cortisol, Insulin Resistance and Zinc in Obesity: a Mini-Review

Adipose tissue is considered an endocrine organ and its excess compromises the immune response and the metabolism of hormones and nutrients. Furthermore, visceral fat accumulation contributes to increased cortisol synthesis, which in turn induces metallothionein and Zip14 expression, which are proteins that contribute to reducing plasma zinc levels. Zinc plays a critical role in the secretion and signaling of insulin. Changes in the biochemical parameters of zinc, as observed in individuals who are obese, contribute to the manifestation of related disorders such as insulin resistance. Thus, the purpose of this review is to provide an update on the current information on the relationship between cortisol, zinc, and insulin resistance in obesity. The data in the literature provide evidence that cortisol affects zinc metabolism, and indicate possible repercussions on insulin signaling that might contribute to the development of resistance to the actions of insulin in obesity.

Mutations in PIK3C2A cause syndromic short stature, skeletal abnormalities, and cataracts associated with ciliary dysfunction

PIK3C2A is a class II member of the phosphoinositide 3-kinase (PI3K) family that catalyzes the phosphorylation of phosphatidylinositol (PI) into PI(3)P and the phosphorylation of PI(4)P into PI(3,4)P2. At the cellular level, PIK3C2A is critical for the formation of cilia and for receptor mediated endocytosis, among other biological functions. We identified homozygous loss-of-function mutations in PIK3C2A in children from three independent consanguineous families with short stature, coarse facial features, cataracts with secondary glaucoma, multiple skeletal abnormalities, neurological manifestations, among other findings. Cellular studies of patient-derived fibroblasts found that they lacked PIK3C2A protein, had impaired cilia formation and function, and demonstrated reduced proliferative capacity. Collectively, the genetic and molecular data implicate mutations in PIK3C2A in a new Mendelian disorder of PI metabolism, thereby shedding light on the critical role of a class II PI3K in growth, vision, skeletal formation and neurological development. In particular, the considerable phenotypic overlap, yet distinct features, between this syndrome and Lowe’s syndrome, which is caused by mutations in the PI-5-phosphatase OCRL, highlight the key role of PI metabolizing enzymes in specific developmental processes and demonstrate the unique non-redundant functions of each enzyme. This discovery expands what is known about disorders of PI metabolism and helps unravel the role of PIK3C2A and class II PI3Ks in health and disease.

Identifying the genetic basis of rare disorders can provide insight into gene function, susceptibility to disease, guide the development of new therapeutics, improve opportunities for genetic counseling, and help clinicians evaluate and potentially treat complicated clinical presentations. However, it is estimated that the genetic basis of approximately one-half of all rare genetic disorders remains unknown. We describe one such rare disorder based on genetic and clinical evaluations of individuals from 3 unrelated consanguineous families with a similar constellation of features including short stature, coarse facial features, cataracts with secondary glaucoma, multiple skeletal abnormalities, neurological manifestations including stroke, among other findings. We discovered that these features were due to deficiency of the PIK3C2A enzyme. PIK3C2A is a class II member of the phosphoinositide 3-kinase (PI3K) family that catalyzes the phosphorylation of the lipids phosphatidylinositol (PI) into PI(3)P and the phosphorylation of PI(4)P into PI(3,4)P2 that are essential for a variety of cellular processes including cilia formation and vesicle trafficking. This syndrome is the first monogenic disorder caused by mutations in a class II PI3K family member and thus sheds new light on their role in human development.

Zinc and Insulin Resistance: Biochemical and Molecular Aspects

Studies have shown the participation of minerals in mechanisms involved in the pathogenesis of insulin resistance. Zinc, in particular, seems to play an important role in the secretion and action of this hormone. Therefore, the aim of this review is to understand the role of zinc in increasing insulin sensitivity. We conducted a search of articles published in the PubMed and ScienceDirect database selected from March 2016 to February 2018, using the keywords "zinc," "insulin," "insulin resistance," "insulin sensitivity," and "supplementation." Following the eligibility criteria were selected 53 articles. The scientific evidences presented in this review show the importance of zinc and their carrier proteins in the synthesis and secretion of insulin, as well as in the signaling pathway of action of this hormone. Zinc deficiency is associated with glucose intolerance and insulin resistance; however, the effectiveness of the intervention with the zinc supplementation is still inconclusive.

ZNF185-derived peptide induces fertility suppression in mice

Zinc finger protein 185 (ZNF185) belongs to the ZNF family and is involved in male reproduction. However, it is unclear whether ZNF185 may be a target candidate for contraceptive vaccines. In this study, antigenic peptides derived from ZNF185 were prepared, and their immune contraceptive effects were investigated using mice. Results from enzyme-linked immunosorbent assay (ELISAs) showed that peptide immunization induced an antibody titre increase that reached a peak in week 12. Peptide-3 and peptide-4 were then chosen for subsequent experiments. The results of the fertility assays showed that peptide immunization inhibited the mating and fertility rates of the mice, whereas there were no obvious changes in the number of pups per litter. Subsequently, epididymal sperm was analysed. The results demonstrated that the sperm count and sperm motility were significantly decreased in the peptide group, while the amount of abnormal sperm was significantly increased in the peptide-3 group. The male reproductive organs were also evaluated. There were no obvious differences in testis or epididymal weights, in the diameters of the seminiferous tubules, or in the thicknesses of the seminiferous epithelium between the peptide group and the phosphate buffer saline (PBS) group. In addition, histological analysis indicated that there were no obvious pathologic changes in testis and epididymal histology in the peptide group; however, the number of spermatozoa present in the epididymal lumen of the peptide group was significantly decreased when compared with the PBS group. Our study demonstrates for the first time that peptides derived from ZNF185 may induce fertility suppression in mice without damaging reproductive organs. These peptides have the potential to be used as a male contraceptive vaccine.

Connecting homocysteine and obesity through pyroptosis, gut microbiome, epigenetics, peroxisome proliferator-activated receptor γ, and zinc finger protein 407

Although homocysteine (Hcy), a part of the epigenome, contributes to cell death by pyroptosis and decreases peroxisome proliferator-activated receptor γ (PPARγ) levels, the mechanisms are unclear. Hcy is found in high concentrations in the sera of obese individuals, which can elicit an immune response as well by hypermethylating CpG islands of specific gene promoters, a marker of epigenetics. Hcy has also been established to chelate divalent metal ions like Cu²⁺ and Zn²⁺, but this role of Hcy has not been established in relationship with obesity. It has been known for a while that PPARγ dysregulation results in various metabolic disorders including glucose and lipid metabolism. Recently, zinc finger protein 407 (Zfp407) is reported to regulate PPARγ target gene expression without affecting PPARγ transcript and protein levels by synergistically working with PPARγ. However, the mechanism(s) of this synergy, as well as other factors contributing to or inhibiting this synergism, have not been proven. This review suggests that Hcy contributes to pyroptosis, changes gut microbiome, and alters PPARγ-dependent mechanism(s) via Zfp407-mediated upregulated adipogenesis and misbalanced fatty acid metabolism, which can predispose to obesity and, consequently, obesity-related metabolic disorders.

Argirein alleviates vascular endothelial insulin resistance through suppressing the activation of Nox4-dependent O2- production in diabetic rats

BACKGROUND

Insulin resistance in endothelial cells contributes to the development of cardiovascular disease in type 2 diabetes mellitus (T2DM). Therefore, there are great potential clinical implications in developing pharmacological interventions targeting endothelial insulin resistance. Our previous studies indicated that argirein which was developed by combining rhein with L-arginine by a hydrogen bond, could substantially relieved stress related exacerbation of cardiac failure and alleviated cardiac dysfunction in T2DM, which was associated with suppressing NADPH oxidase activity. However, it is unclear whether argirein treatment attenuates the vascular lesion and dysfunction in T2DM and its underlying mechanisms.

METHODS AND RESULTS

The rat aortic endothelial cells (RAECs) were used to treat with palmitic acid (PA), a most common saturated free fatty acid, which could induce insulin resistance. It was showed that argirein increased glucose uptake and glucose transporter-4 (Glut4) expression and reversed the phosphorylation of IRS-1-ser307 and AKT-ser473, consequently resulting in the increase of the production of eNOS and NO in PA-induced RAECs. We further found that argirein blocked the Nox4-dependent superoxide (O₂^-.) generation, which regulated glucose metabolism in RAECs during PA stimulation. In vitro, argirein increased the release of endothelial NO to relieve the vasodilatory response to acetylcholine and insulin, and restored the expression of Nox4 and pIRS-1-ser307 in the aorta endothelium of high-fat diet (HFD)-fed rats following an injection of streptozocin (STZ).

CONCLUSION

These results suggested that argirein could improve endothelial insulin resistance which was attributed to inhibiting Nox4-dependent redox signaling in RAECs. These studies thus revealed the novel effect of argirein to prevent the vascular complication in T2DM.

Trace element status in type 2 diabetes: A meta-analysis

Introduction

Type 2 diabetes is a chronic metabolic disorder that has been associated with alterations in the status of trace elements, including zinc, copper, iron and manganese. However, clinical studies reporting statuses of these trace elements in type 2 diabetes patients compared to controls have shown conflicting results.

Objective

This meta-analysis aimed to summarize the existing literature on the statuses of zinc, copper, iron, and manganese in Type 2 diabetes mellitus patients.

Methods

A literature search of Embase, PubMed, EBSCOHost, ScienceDirect, Scopus, Cochrane library and Web of Science electronic databases was conducted to find studies published from 1970 to November 2016 that compared the trace elements of interest between type 2 diabetic patients and healthy controls. Keywords used were type 2 diabetes, diabetes, hyperglycemia, insulin, glucose, HbA1c, trace elements, micronutrients, zinc, manganese, copper, ceruloplasmin, iron and ferritin. The bias corrected Hedges' g, was utilized as the effect sizes. Due to the biological interaction between trace elements, it is important to collectively evaluate the statuses of these minerals in type 2 diabetes. Thus, the robust variance estimation method was chosen to handle dependency between multiple outcomes.

Results

A total of 52 studies met the inclusion criteria, amounting to 98 effect sizes. Diabetic patients (n=20183) had significantly lower zinc status when compared to controls (effect size = -1.73, p<0.01); whereas copper (effect size = 1.10, p<0.05) and ferritin levels (effect size = 1.05, p<0.01) were significantly higher. Although not significant, ceruloplasmin (effect size = 1.85, p=0.06) and iron (effect size = 1.42, p=0.06) levels were higher, and manganese (effect size = 0.27, p=0.34) was lower in patients.

Conclusion

Results from this meta-analysis indicate lower zinc status accompanied by increased copper and ferritin levels in patients with type 2 diabetes when compared to controls.

Perinatal exposure to low dose 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) alters sperm DNA methylation in adult rats

Polybrominated diphenyl ethers (PBDEs) are a group of ubiquitous reproductive toxins. Given that spermatogenesis requires extensive epigenetic changes, we hypothesize that PBDEs impact sperm DNA methylation. Pregnant Wistar rats were exposed perinatally to 0.2mg/kg 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and caudal epididymal sperm were collected from offspring on postnatal days (PNDs) 65 and 120. Libraries were prepared from sperm DNA and sequenced with an average of 18.0 million unique reads per sample. Differential methylated regions (DMRs) were identified via MethPipe package. BDE-47 exposure increased DNA methylation of epididymal sperm on PND 65 in genes, promoters and intergenic regions; however, on PND120 methylation decreased in these genomic elements. We identified 21 and 9 exposure-related DMRs in sperm collected on PND65 and PND120, respectively. Two DMRs overlapped between the two time-points. This is the first study to demonstrate that environmentally-relevant perinatal exposure to PBDE results in long-lasting changes in sperm DNA methylation.

Zinc finger protein 407 overexpression upregulates PPAR target gene expression and improves glucose homeostasis in mice

The peroxisome proliferator-activated receptor (PPAR) family of nuclear receptors is central to the pathophysiology and treatment of metabolic disease through the receptors' ability to regulate the expression of genes involved in glucose homeostasis, adipogenesis, and lipid metabolism. However, the mechanism by which PPAR is regulated remains incompletely understood. We generated a transgenic mouse strain (ZFP-TG) that overexpressed Zfp407 primarily in muscle and heart. Transcriptome analysis by RNA-Seq identified 1,300 differentially expressed genes in the muscle of ZFP-TG mice, among which PPAR target genes were significantly enriched. Among the physiologically important PPARγ target genes, Glucose transporter (Glut)-4 mRNA and protein levels were increased in heart and muscle. The increase in Glut4 and other transcriptional effects of Zfp407 overexpression together decreased body weight and lowered plasma glucose, insulin, and HOMA-IR scores relative to control littermates. When placed on high-fat diet, ZFP-TG mice remained more glucose tolerant than their wild-type counterparts. Cell-based assays demonstrated that Zfp407 synergistically increased the transcriptional activity of all PPAR subtypes, PPARα, PPARγ, and PPARδ. The increased PPAR activity was not associated with increased PPAR mRNA or protein levels, suggesting that Zfp407 posttranslationally regulates PPAR activity. Collectively, these results demonstrate that Zfp407 overexpression improved glucose homeostasis. Thus, Zfp407 represents a new drug target for treating metabolic disease.

Antidiabetic activity of perylenequinonoid-rich extract from Shiraia bambusicola in KK-Ay mice with spontaneous type 2 diabetes mellitus

ETHNOPHARMACOLOGICAL RELEVANCE

Bitter and cold traditional Chinese medicines (TCMs) have been long used to treat diabetes mellitus (DM) based on unique medical theory system since ancient China. As one of bitter and cold TCMs, the stromatas of Shiraia bambusicola have been used for the treatment of DM and exerted clinical effects to a certain extent. However, the corresponding active principles and antidiabetic mechanism of the TCM still remain unknown. Therefore, the aim of the present investigation was to evaluate the potential antidiabetic effect of the active Shiraia bambusicola EtOAc extract (SB-EtOAc) in vitro and in vivo, and elucidate its probable antidiabetic mechanism.

MATERIALS AND METHODS

A LC-PDA-ESIMS protocol was developed to determine the chemical principles of the active EtOAc extract rapidly and unambiguously. The effect of SB-EtOAc on the glucose transporter type 4 (GLUT4) translocation and glucose uptake in L6 cells was examined. SB-EtOAc was orally administration at the dose of 30, 60 and 120mg/kg/d in KK-Ay mice, for 21 days. Body weight, plasma glucose, oral glucose tolerance test, fasted blood glucose levels, oral glucose tolerance test and insulin tolerance test, serum insulin and blood-lipid indexes were measured. GLUT4 on L6 cells membrane and phosphorylation of the AMP-activated protein kinase (p-AMPK) expression in L6 cells were measured. The GLUT4 and p-AMPK expression in KK-Ay mice skeletal muscle were measured. Phosphorylation of the acetyl-CoA carboxylase (p-ACC) and p-AMPK were measured.

RESULTS

In vitro, SB-EtOAc exhibited a strong effect of stimulation on GLUT4 translocation by 3.2 fold in L6 cells compared with basal group, however, the selective AMPK inhibitor compound C can completely inhibit the AMPK pathway and prevent the GLUT4 translocation caused by SB-EtOAc. The further western blotting experiments showed that SB-EtOAc can stimulate AMPK phosphorylation in L6 cells and improve the expression of GLUT4. In vivo, SB-EtOAc can improve the KK-Ay mice insulin resistant and oral glucose tolerance to a certain extent. And the body weight, blood glucose levels and the serum TC, TG, FFA, AST, ALT and LDL-C were significantly reduced and HDL-C were increased after 3 weeks treatment. Mechanistically, phosphorylation of the AMPK and ACC had been improved obviously and the levels of AMPK phosphorylation and GLUT4 had been also enhanced.

CONCLUSION

In vitro, SB-EtOAc exhibited a strong effect of stimulation on GLUT4 translocation and improved significantly the glucose uptake. In vivo, SB-EtOAc significantly improved oral glucose tolerance and the insulin resistant as well as glucolipid metabolism. In this study, SB-EtOAc displayed promising positive antidiabetic activity in vitro and in vivo, partly by modulating AMPK-GLUT4 and AMPK-ACC signaling pathways.

Signaling pathways involved in cardiac energy metabolism

Various signaling pathways coordinate energy metabolism and contractile function in the heart. Myocardial uptake of long-chain fatty acids largely occurs by facilitated diffusion, involving the membrane-associated protein, CD36. Glucose uptake, the rate-limiting step in glucose utilization, is mediated predominantly by the glucose transporter protein, GLUT4. Insulin and contraction-mediated AMPK signaling each are implicated in tightly regulating these myocardial 'gate-keepers' of energy balance, that is, CD36 and GLUT4. The insulin and AMPK signaling cascades are complex and their cross-talk is only beginning to be understood. Moreover, transcriptional regulation of the CD36 and GLUT4 is significantly understudied. This review focuses on recent advances on the role of these signaling pathways and transcription factors involved in the regulation of CD36 and GLUT4.

Reduction of sitting time has a positive effect on the decrease of insulin resistance in patients with non-alcoholic fatty liver disease

Introduction

Non-alcoholic fatty liver disease (NAFLD) affects a large part of the human population. One of the major environmental factors associated with the risk of NAFLD is the lack of physical activity.

Aim

To compare the level of physical activity and the insulin resistance in NAFLD patients.

Material and methods

Thirty patients with NAFLD underwent a six-month dietary intervention based on the principles of classical dietetics. Data about diet and physical activity was based on 72-hour nutrition diaries and International Physical Activity Questionnaire (IPAQ). Standard blood biochemical analyses were carried out before and after diet at the University Hospital Laboratory.

Results

The study showed that total physical activity and physical activity in leisure time are negatively correlated with insulin resistance (HOMA-IR) (p < 0.05). Insulin (p < 0.05), body weight (p < 0.05), and waist-hip ratio (WHR) (p < 0.05) were also negatively correlated with physical activity in free time. In addition, we noticed a positive correlation between sitting time and the risk of insulin resistance, in the case of HOMA-IR and insulin concentration (p < 0.05).

Conclusions

Dietary intervention and a physical activity plan are important factors in the treatment of non-alcoholic fatty liver disease. Taking regular exercise increases insulin sensitivity and prevents further development of the disease. It seems that diet and physical activity are not the only one risk factors of NAFLD. Our study reveals that the reduction of sitting time has a positive effect on the level of insulin and it reduces insulin resistance in patients with NAFLD.

HIF-1α and PPARγ during physiological cardiac hypertrophy induced by pregnancy: Transcriptional activities and effects on target genes

Hypoxia inducible factor 1-α (HIF-1α) and peroxisome proliferator-activated receptor γ (PPARγ) are transcription factors that activate genes involved in cellular metabolism. Physiological cardiac hypertrophy induced by pregnancy initiates compensatory changes in metabolism. However, the contributions of HIF-1α and PPARγ to this physiological status and to its reversible, metabolic process (postpartum) in the heart are not well-defined. Therefore, the aim of the present study was to evaluate the transcriptional activities of HIF-1α and PPARγ in the left ventricle of rats before, during, and after pregnancy. Furthermore, the effects of pregnancy on target genes of glycolysis and glycerol-lipid biosynthesis, key regulatory enzymes, and metabolic intermediates were evaluated. The activities of HIF-1α and PPARγ increased 1.2- and 1.6-fold, respectively, during pregnancy, and decreased to basal levels during postpartum. Expressions of mRNA for glucose transport 1 (GLUT1), enzymes of glycolysis (HK2, PFKM, and GAPDH) and glycerol-lipid biosynthesis (GPAT and GPD1) increased 1.6- to 14-fold during pregnancy and returned to basal levels postpartum. The increase in GPD1 expression translated to an increase in its activity, but such was not the case for GAPDH suggesting that post-translational regulation of these proteins is differential during pregnancy. Glycolytic (glucose, lactate, and DHAP) and glycerol-lipid biosynthesis (G3P and FFA) intermediates increased with pregnancy and were maintained postpartum. The results demonstrate that pregnancy-induced, physiological cardiac hypertrophy activates the expression of genes involved in glycolytic and glycerol-lipid biosynthesis suggesting that the shift in cardiac metabolism is mediated by the activation of HIF-1α and PPARγ.

Zinc and diabetes mellitus: understanding molecular mechanisms and clinical implications

Background

Diabetes mellitus is a leading cause of morbidity and mortality worldwide. Studies have shown that Zinc has numerous beneficial effects in both type-1 and type-2 diabetes. We aim to evaluate the literature on the mechanisms and molecular level effects of Zinc on glycaemic control, β-cell function, pathogenesis of diabetes and its complications.

Methods

A review of published studies reporting mechanisms of action of Zinc in diabetes was undertaken in PubMed and SciVerse Scopus medical databases using the following search terms in article title, abstract or keywords; (“Zinc” or “Zn”) and (“mechanism” or “mechanism of action” or “action” or “effect” or “pathogenesis” or “pathology” or “physiology” or “metabolism”) and (“diabetes” or “prediabetes” or “sugar” or “glucose” or “insulin”).

Results

The literature search identified the following number of articles in the two databases; PubMed (n = 1799) and SciVerse Scopus (n = 1879). After removing duplicates the total number of articles included in the present review is 111. Our results show that Zinc plays an important role in β-cell function, insulin action, glucose homeostasis and the pathogenesis of diabetes and its complications.

Conclusion

Numerous in-vitro and in-vivo studies have shown that Zinc has beneficial effects in both type-1 and type-2 diabetes. However further randomized double-blinded placebo-controlled clinical trials conducted for an adequate duration, are required to establish therapeutic safety in humans.

Electronic supplementary material

The online version of this article (doi:10.1186/s40199-015-0127-4) contains supplementary material, which is available to authorized users.