Neurexin-3 in the paraventricular nucleus of the hypothalamus regulates body weight and glucose homeostasis independently of food intake.

Neurexin-3 (Nrxn3) has been genetically associated with obesity, but the underlying neural mechanisms remain poorly understood. This study aimed to investigate the role of Nrxn3 in the paraventricular nucleus of the hypothalamus (PVN) in regulating energy balance and glucose homeostasis. We found that Nrxn3 expression in the PVN was upregulated in response to metabolic stressors, including cold exposure and fasting. Using Cre-loxP technology, we selectively ablated Nrxn3 in CaMKIIα-expressing neurons of the PVN in male mice. This genetic manipulation resulted in marked weight gain attributable to increased adiposity and impaired glucose tolerance, without affecting food intake. Our findings identify PVN CaMKIIα-expressing neurons as a critical locus where Nrxn3 modulates energy balance by regulating adipogenesis and glucose metabolism, independently of appetite. These results reveal a novel neural mechanism potentially linking Nrxn3 dysfunction to obesity pathogenesis, suggesting that targeting PVN Nrxn3-dependent neural pathways may inform new therapeutic approaches for obesity prevention and treatment.

Multifunctional Nanoprobe for the Delivery of Therapeutic siRNA and Real-Time Molecular Imaging of Parkinson's Disease Biomarkers.

Parkinson's disease (PD) has been recently associated with the excessive expression of matrix metalloproteinase 3 (MMP3). One of the major challenges in treating PD is to effectively detect and inhibit the early MMP3 activities to relieve the neural stress and inflammation responses. Previously, numerous upconversion nanoparticle (UCNP)-based nanoprobes have been designed for the detection of biomarkers in neurodegenerative diseases. To further improve the performance of the conventional nanoprobes, we introduced novel reporting units and integrated the therapeutic reagents to fabricate a theragnostic platform for PD and other neurodegenerative diseases. Here, we designed a multifunctional UCNP/aggregation-induced emission luminogen (AIEgen)-based nanoprobe to effectively detect the time-lapse MMP3 activities in the inflammatory catecholaminergic SH-SY5Y cells and simultaneously deliver the MMP3-siRNA into the stressed catecholaminergic SH-SY5Y cells, inhibiting the MMP3-induced inflammatory neural responses. The unique features of our UCNP/AIEgen-based nanoprobe platform shed light on the development of a novel theragnostic probe for the early diagnosis and cure of neurodegenerative diseases.

Therapeutic effect of a histone demethylase inhibitor in Parkinson's disease.

Iron accumulation in the substantia nigra is recognized as a hallmark of Parkinson's disease (PD). Therefore, reducing accumulated iron and associated oxidative stress is considered a promising therapeutic strategy for PD. However, current iron chelators have poor membrane permeability and lack cell-type specificity. Here we identified GSK-J4, a histone demethylase inhibitor with the ability to cross blood brain barrier, as a potent iron suppressor. Only a trace amount of GSK-J4 significantly and selectively reduced intracellular labile iron in dopaminergic neurons, and suppressed H2O2 and 6-OHDA-induced cell death in vitro. The iron-suppressive effect was mainly mediated by inducing an increase in the expression of the iron exporter ferroportin-1. In parallel, GSK-J4 rescued dopaminergic neuron loss and motor defects in 6-OHDA-induced PD rats, which was accompanied by reduction of oxidative stress. Importantly, GSK-J4 rescued the abnormal changes of histone methylation, H3K4me3 and H3K27me3 during 6-OHDA treatment although the iron-suppressive and neuroprotective effects were sensitive to H3K4me3 inhibition only. Also, upregulating H3K4me3 increased ferroportin-1 expression and neuroprotection. Taken together, we demonstrate a previously unappreciated action of GSK-J4 on cell-specific iron suppression and neuroprotection via epigenetic mechanism. Compared with conventional iron chelators, this compound has a stronger therapeutic potential for PD.

Brain Hepcidin Suppresses Major Pathologies in Experimental Parkinsonism.

Despite intensive research on Parkinson disease (PD) for decades, this common neurodegenerative disease remains incurable. We hypothesize that abnormal iron accumulation is a common thread underlying the emergence of the hallmarks of PD, namely mitochondrial dysfunction and α-synuclein accumulation. We investigated the powerful action of the main iron regulator hepcidin in the brain. In both the rotenone and 6-hydroxydopamine models of PD, overexpression of hepcidin by means of a virus-based strategy prevented dopamine neuronal loss and suppressed major pathologies of Parkinsonism as well as motor deficits. Hepcidin protected rotenone-induced mitochondrial deficits by reducing cellular and mitochondrial iron accumulation. In addition, hepcidin decreased α-synuclein accumulation and promoted clearance of α-synuclein through decreasing iron content that leads to activation of autophagy. Our results not only pinpoint a critical role of iron-overload in the pathogenesis of PD but also demonstrate that targeting brain iron levels through hepcidin is a promising therapeutic direction.

A limbic circuitry involved in emotional stress-induced grooming.

Prolonged exposure to negative stressors could be harmful if a subject cannot respond appropriately. Strategies evolved to respond to stress, including repetitive displacement behaviours, are important in maintaining behavioural homoeostasis. In rodents, self-grooming is a frequently observed repetitive behaviour believed to contribute to post-stress de-arousal with adaptive value. Here we identified a rat limbic di-synaptic circuit that regulates stress-induced self-grooming with positive affective valence. This circuit links hippocampal ventral subiculum to ventral lateral septum (LSv) and then lateral hypothalamus tuberal nucleus. Optogenetic activation of this circuit triggers delayed but robust excessive grooming with patterns closely resembling those evoked by emotional stress. Consistently, the neural activity of LSv reaches a peak before emotional stress-induced grooming while inhibition of this circuit significantly suppresses grooming triggered by emotional stress. Our results uncover a previously unknown limbic circuitry involved in regulating stress-induced self-grooming and pinpoint a critical role of LSv in this ethologically important behaviour.

Subtractive proteomics and systems biology analysis revealed novel drug targets in Mycoplasma genitalium strain G37.

Mycoplasma genitalium is one of the sexually transmitted pathogens that cause significant morbidity in the host. The development of effective therapeutic procedures is urgently needed to counter the multi-drug resistant events imposed by this pathogen. In the current version of M. genitalium G37 genome, 512 open reading frames have been identified. The function of 91 proteins encoded by M. genitalium genes was found to be hypothetical and these proteins were termed hypothetical proteins (HPs). This study aims to carry out functional characterization of HPs by a systems biology approach. Functional assignments of 61 HPs were made with high confidence. They belong to different functional groups, such as DNA-binding proteins, helicases and transporters. Approximately 26% of HPs were identified as transporters, suggesting that M. genitalium is likely to rely on the exogenous nutrient supply for survival. A group of 20 proteins was predicted to be virulence factors, indicating the pathogenic characteristics of M. genitalium. Among the coding proteins, six proteins were pathogen-specific and could serve as potential drug targets by subtractive proteomics analysis. Network analysis of the HPs suggested that several critical proteins were involved in SOS response and stringent response in M. genitalium. These findings provided a better picture of M. genitalium genome and novel clues for studying the potential infection mechanism in this bacterium.

Regulating ferroportin-1 and transferrin receptor-1 expression: A novel function of hydrogen sulfide.

Hydrogen sulfide (H2 S) has a significant effect on the regulation of interleukin-6 (IL-6) and signal transducer and activator of transcription 3 (STAT3) activities, while IL-6 directly regulates hepcidin expression via STAT3. We therefore hypothesized that H 2 S has a role in body iron homeostasis by regulating the expression of iron transport proteins via the IL-6/STAT3/Hepcidin pathway. Here, we investigated the effects of two H 2 S donors sodium hydrosulfide and GYY4137 on the expression of ferroportin-1 (Fpn1), transferrin receptor-1 (TfR1), hepcidin, IL-6 and pSTAT3 in the spleen of mice in vivo and peritoneal macrophage in vitro. We also examined the effects of H 2 S on serum iron, transferrin saturation, and ferritin light chain contents in the spleen, and on nitrite content, nuclear factor erythroid 2-related factor-2 (Nrf2) and iron regulatory protein 1 (IRP1) in the macrophages. We demonstrated that H 2 S regulates the expression of TfR1 and Fpn1 in the spleen in vivo and in peritoneal macrophages in vitro predominantly via the IL-6/pSTAT3/hepcidin pathway, under the conditions of inflammation induced by lipopolysaccharides. We also provide evidence that under uninflamed conditions, the regulation of Fpn1 and TfR1 expression by H 2 S, both in vivo and in vitro, are mediated by the nitric oxide (NO)/Nrf2 and iron regulatory protein/iron responsive element pathways, respectively, which are independent of IL-6/pSTAT3/hepcidin signals. These findings show that H 2 S is a key player in iron homeostasis under not only the inflamed conditions but also uninflamed conditions.

Adenine alleviates iron overload by cAMP/PKA mediated hepatic hepcidin in mice.

Hemochromatosis is prevalent and often associated with high rates of morbidity and mortality worldwide. The safe alternative iron-reducing approaches are urgently needed in order to better control iron overload. Our unbiased vitamin screen for modulators of hepcidin, a master iron regulatory hormone, identifies adenine (vitamin B4) as a potent hepcidin agonist. Adenine significantly induced hepcidin mRNA level and promoter activity activation in human cell lines, possibly through BMP/SMAD pathway. Further studies in mice validated the effect of adenine on hepcidin upregulation. Consistently, adenine dietary supplement in mice led to an increase of hepatic hepcidin expression compared with normal diet-fed mice via BMP/SMAD pathway. Notably, adenine-rich diet significantly ameliorated iron overload accompanied by the enhanced hepcidin expression in both high iron-fed mice and in Hfe-/- mice, a murine model of hereditary hemochromatosis. To further validate this finding, we selected pharmacological inhibitors against BMP (LDN193189). We found LDN193189 strongly blocked the hepcidin induction by adenine. Moreover, we uncovered an essential role of cAMP/PKA-dependent axis in triggering adenine-induced hepcidin expression in primary hepatocytes by using 8 br cAMP, a cAMP analog, and H89, a potent inhibitor for PKA signaling. These findings suggest a potential therapeutic role of adenine for hereditary hemochromatosis.

Cystathionine ß-synthase is required for body iron homeostasis.

Cystathionine ß-synthase (CBS) catalyzes the transsulfuration pathway and contributes, among other functions, to the generation of hydrogen sulfide. In view of the exceptionally high expression of CBS in the liver and the common interleukin-6 pathway used in the regulatory systems of hydrogen sulfide and hepcidin, we speculate that CBS is involved in body iron homeostasis. We found that CBS knockout (CBS-/- ) mice exhibited anemia and a significant increase in iron content in the serum, liver, spleen, and heart, along with severe damage to the liver, displaying a hemochromatosis-like phenotype. A high level of hepatic and serum hepcidin was also found. A major cause of the systemic iron overload is the reduced iron usage due to suppressed erythropoiesis, which is consistent with an increase in interleukin-6 and reduced expression of erythropoietin. Importantly, in the liver, absence of CBS caused both a reduction in the transcriptional factor nuclear factor erythroid 2-related factor-2 and an up-regulation of hepcidin that led to a decrease in the iron export protein ferroportin 1. The resulting suppression of iron export exacerbates iron retention, causing damage to hepatocytes. Finally, administration of CBS-overexpressing adenovirus into CBS mutant mice could partially reverse the iron-related phenotype. CONCLUSION: Our findings point to a critical role of CBS in iron homeostasis of the body, and the liver in particular; it is likely that a hemochromatosis-like phenotype in patients can be induced by aberration not only in the expression of key molecules in the hepcidin pathway but also of those related to CBS. (Hepatology 2018;67:21-35).

Ghrelin is Negatively Correlated with Iron in the Serum in Human and Mice.

BACKGROUND/AIMS: The studies in the patients with iron deficiency anemia (IDA) implied the existence of the association of ghrelin with iron or hepcidin levels in the plasma under the pathophysiological conditions. We hypothesized that fasting may be able to affect iron metabolism via ghrelin under the physiological conditions. METHODS: We investigated the effects of fasting on serum ghrelin and iron contents in healthy volunteers (23-31 years) and C57BL/6 male mice (8-week-olds) under the physiological conditions. RESULTS: Fasting induced a significant elevation in both total ghrelin and acylated ghrelin and a reduction in iron levels in the serum of both human and mice. Correlation analysis demonstrated that total ghrelin or acylated ghrelin is negatively correlated with iron in the serum in human and mice. CONCLUSION: Ghrelin has a role to reduce serum iron under the conditions of fasting.

The dietary flavonoid myricetin regulates iron homeostasis by suppressing hepcidin expression.

Hepcidin, a master regulator of iron homeostasis, is a promising target in treatment of iron disorders such as hemochromatosis, anemia of inflammation and iron-deficiency anemia. We previously reported that black soybean seed coat extract could inhibit hepcidin expression. Based on this finding, we performed a screen in cultured cells in order to identify the compounds in black soybeans that inhibit hepcidin expression. We found that the dietary flavonoid myricetin significantly inhibited the expression of hepcidin both in vitro and in vivo. Treating cultured cells with myricetin decreased both HAMP mRNA levels and promoter activity by reducing SMAD1/5/8 phosphorylation. This effect was observed even in the presence of bone morphogenic protein-6 (BMP6) and interleukin-6 (IL-6), two factors that stimulate hepcidin expression. Furthermore, mice that were treated with myricetin (either orally or systemically) had reduced hepatic hepcidin expression, decreased splenic iron levels and increased serum iron levels. Notably, myricetin-treated mice increased red blood cell counts and hemoglobin levels. In addition, pretreating mice with myricetin prevented LPS-induced hypoferremia. We conclude that myricetin potently inhibits hepcidin expression both in vitro and in vivo, and this effect is mediated by altering BMP/SMAD signaling. These experiments highlight the feasibility of identifying and characterizing bioactive phytochemicals to suppress hepcidin expression. These results also suggest that myricetin may represent a novel therapy for treating iron deficiency-related diseases.

Maternal lead exposure and risk of congenital heart defects occurrence in offspring.

Maternal lead exposure may be harmful to fetal development. However, sufficient evidence was lacked about the risk on cardiac development in offspring. To explore the association between maternal lead exposure and risks of congenital heart defects (CHDs) occurrence in fetuses, a case-control study was adopted during pregnant women making antenatal examinations. The maternal hair lead levels were measured by using inductively coupled plasma mass spectrometry (ICP-MS), and logistic regression analysis was used to calculate the odds ratio (OR). Three hundred and sixteen cases and 348 controls were eligible to the study. The median level of lead in maternal hair of case (0.670ng/mg) was significantly higher (AOR 3.07, 95% CI 2.00-4.72) than that of the control (0.461ng/mg), including the CHD cases with or without extracardiac malformations (AOR 3.55, 2.94, respectively). Maternal lead exposure is associated with the risk of some subtypes of CHDs occurrence in offspring. The potential dose-response relationship is also presented.

Black soyabean seed coat extract regulates iron metabolism by inhibiting the expression of hepcidin.

Hepcidin, a key regulator of Fe homeostasis, is an ideal drug target for treating patients with Fe disorders such as haemochromatosis, anaemia of chronic inflammation and Fe-deficiency anaemia. However, whether (and how) traditional Chinese black foods (e.g., black soyabeans) target hepcidin and improve Fe-deficiency anaemia remains unclear. Herein, we report that black soyabean seed coat extract (BSSCE) can potently inhibit the in vitro and in vivo expression of hepcidin. In the present study, in cells treated with 200 µg/ml BSSCE, hepcidin expression was found to be reduced to only 6% of the control levels (P<0.01). An AIN-76A diet containing 2% BSSCE was fed to 8-week-old male C57BL/6 mice for 0, 1, 7, 15 or 30 d; importantly, compared with the day 0 group, the day 7 group exhibited nearly a 50% decrease in hepatic hepcidin expression (P<0.01), a 35% decrease in splenic Fe concentrations (P<0.05) and a 135% increase in serum Fe concentrations (P<0.05). Mechanistically, the effect of BSSCE on hepcidin expression was mediated via a reduction in the phosphorylation levels of mothers against decapentaplegic homolog proteins (Smad)1/5/8. Consequently, the mice in the day 30 group exhibited large increases in erythrocyte counts (111% v. day 0, P<0.01), Hb concentrations (109%, P<0.01) and haematocrit values (108%, P<0.01). In conclusion, these results indicate that black soyabean extract regulates Fe metabolism by inhibiting the expression of hepcidin. This finding can be used to optimise the intervention of patients with hepcidin-related diseases, including Fe-deficiency anaemia.

Associations between serum hepcidin, ferritin and Hb concentrations and type 2 diabetes risks in a Han Chinese population.

Systemic Fe overload can contribute to abnormal glucose metabolism and the onset of type 2 diabetes (T2D). Although hepcidin is the master regulator of systemic Fe homeostasis, few studies have systematically evaluated the associations of serum hepcidin concentrations with Fe metabolism parameters and risks for the development of T2D. In this regard, whether hepcidin concentrations are associated with T2D remains controversial. We measured serum hepcidin and ferritin concentrations in a case-control study of 1259 Han Chinese participants to evaluate the possible associations of serum hepcidin concentrations with Fe metabolism parameters and risks of T2D. Individuals with diabetes (n 555) and control participants (n 704) were recruited and serum hepcidin and ferritin concentrations were quantified. Additionally, selected biochemical and anthropometric variables were determined. A logistic regression analysis was performed to evaluate the association of serum hepcidin and ferritin concentrations with T2D. A linear regression analysis was used to test for associations between serum hepcidin and ferritin concentrations and a number of clinical, demographic and diabetes-associated variables. We found that serum hepcidin concentrations correlated with Hb and serum ferritin concentrations. No differences in hepcidin concentrations were found between the group with diabetes and the control group. Hepcidin concentrations were not significantly correlated with T2D risk factors. We also found that serum ferritin concentrations were elevated in individuals with diabetes and were positively correlated with both Hb concentrations and T2D risk factors. The present findings suggest that serum ferritin concentrations correlate with T2D risk factors, while serum hepcidin concentrations are positively associated with Hb and serum ferritin concentrations, but do not correlate with T2D.

TMPRSS6, but not TF, TFR2 or BMP2 variants are associated with increased risk of iron-deficiency anemia.

A variety of conditions lead to anemia, which affects one-quarter of the world's population. Previous genome-wide association studies revealed a number of genetic polymorphisms significantly associated with plasma iron status. To evaluate the association of genetic variants in genes involved in iron delivery and hepcidin regulation pathways with the risk of iron-deficiency anemia (IDA), the following single nucleotide polymorphisms were genotyped in 2139 unrelated elderly Chinese women: rs3811647 (TF), rs7385804 (TFR2), rs235756 (BMP2), and rs855791(V736A) and rs4820268 (TMPRSS6, encoding matriptase-2). We identified common variants in TMPRSS6 as being genetic risk factors for both iron deficiency (OR(rs855791) = 1.55, P = 4.96 × 10(-8)) and IDA (OR(rs855791) = 1.78, P = 8.43 × 10(-9)). TMPRSS6 polymorphisms were also associated with lower serum iron (SI) and hemoglobin levels, consistent with their associations to increased iron deficiency and anemia risk. Variants rs3811647 in TF and rs7385804 in TFR2 were associated with reduced SI, serum transferrin and transferrin saturation levels; however, these variants were not associated with iron deficiency or anemia risk. Our findings suggest that TF, TFR2 and TMPRSS6 polymorphisms are significantly associated with decreased iron status, but only variants in TMPRSS6 are genetic risk factors for iron deficiency and IDA.