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Joram D Mul

Acute or chronic exposure to stress can increase the risk to develop major depressive disorder, a severe, recurrent and common psychiatric condition. Depression places an enormous social and financial burden on modern society. Although many depressed patients are treated with antidepressants, their efficacy is only modest, underscoring the necessity to develop clinically effective pharmaceutical or behavioral treatments. Exercise training produces beneficial effects on stress-related mental disorders, indicative of clinical potential. The pro-resilient and antidepressant effects of exercise training have been documented for several decades. Nonetheless, the underlying molecular mechanisms and the brain circuitries involved remain poorly understood. Preclinical investigations using voluntary wheel running, a frequently used rodent model that mimics aspects of human exercise training, have started to shed light on the molecular adaptations, signaling pathways and brain nuclei underlying the beneficial effects of exercise training on stress-related behavior. In this review, I highlight several neurotransmitter systems that are putative mediators of the beneficial effects of exercise training on mental health, and review recent rodent studies that utilized voluntary wheel running to promote our understanding of exercise training-induced central adaptations. Advancements in our mechanistic understanding of how exercise training induces beneficial neuronal adaptations will provide a framework for the development of new strategies to treat stress-associated mental illnesses.

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Sang R Lee, Mi-Young Park, Hyun Yang, Geun-Shik Lee, Beum-Soo An, Bae-kuen Park, Eui-Bae Jeung, and Eui-Ju Hong

Androgens act in concert with vitamin D to influence reabsorption of calcium. However, it is unclear whether androgens directly regulate vitamin D homeostasis or control other cellular events that are related to vitamin D metabolism. To examine whether the expression of vitamin D-related genes in mouse kidney is driven by androgens or androgen-dependent effects, the androgen receptor and other sex steroid receptors were monitored in orchidectomized mice treated with 5α-dihydrotestosterone (DHT). Our results revealed that exposing orchidectomized mice to DHT inhibited the expression of progesterone receptor (Pgr) with or without estrogen receptor α expression, the latter was confirmed by ER-positive (MCF7 and T47D) or -negative (PCT) cells analysis. The loss of Pgr in turn decreased the expression of renal 24-hydroxylase via transcriptional regulation because Cyp24a1 gene has a progesterone receptor-binding site on promoter. When male kidneys preferentially hydroxylate 25-hydroxyvitamin D3 using 24-hydroxylase rather than 25-hydroxyvitamin D3-1-alpha hydroxylase, DHT suppressed the Pgr-mediated 24-hydroxylase expression, and it is important to note that DHT increased the blood 25-hydroxyvitamin D3 levels. These findings uncover an important link between androgens and vitamin D homeostasis and suggest that therapeutic modulation of Pgr may be used to treat vitamin D deficiency and related disorders.

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Matthew Stagl, Mary Bozsik, Christopher Karow, David Wertz, Ian Kloehn, Savin Pillai, Paul J Gasser, Marieke R Gilmartin, and Jennifer A Evans

Glucocorticoid production is gated at the molecular level by the circadian clock in the adrenal gland. Stress influences daily rhythms in behavior and physiology, but it remains unclear how stress affects the function of the adrenal clock itself. Here, we examine the influence of stress on adrenal clock function by tracking PERIOD2::LUCIFERASE (PER2::LUC) rhythms in vitro. Relative to non-stressed controls, adrenals from stressed mice displayed marked changes in PER2::LUC rhythms. Interestingly, the effect of stress on adrenal rhythms varied by sex and the type of stress experienced in vivo. To investigate the basis of sex differences in the adrenal response to stress, we next stimulated male and female adrenals in vitro with adrenocorticotropic hormone (ACTH). ACTH shifted phase and increased amplitude of adrenal PER2::LUC rhythms. Both phase and amplitude responses were larger in female adrenals than in male adrenals, an observation consistent with previously described sex differences in the physiological response to stress. Lastly, we reversed the sex difference in adrenal clock function using stress and sex hormone manipulations to test its role in driving adrenal responses to ACTH. We find that adrenal responsiveness to ACTH is inversely proportional to the amplitude of adrenal PER2::LUC rhythms. This suggests that larger ACTH responses from female adrenals may be driven by their lower amplitude molecular rhythms. Collectively, these results indicate a reciprocal relationship between stress and the adrenal clock, with stress influencing adrenal clock function and the state of the adrenal clock gating the response to stress in a sexually dimorphic manner.

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Louise Ruby Høj Illum, Stine Thorhauge Bak, Sten Lund, and Anders Lade Nielsen

The global rise in metabolic diseases can be attributed to a complex interplay between biology, behavior and environmental factors. This article reviews the current literature concerning DNA methylation-based epigenetic inheritance (intergenerational and transgenerational) of metabolic diseases through the male germ line. Included are a presentation of the basic principles for DNA methylation in developmental programming, and a description of windows of susceptibility for the inheritance of environmentally induced aberrations in DNA methylation and their associated metabolic disease phenotypes. To this end, escapees, genomic regions with the intrinsic potential to transmit acquired paternal epigenetic information across generations by escaping the extensive programmed DNA demethylation that occurs during gametogenesis and in the zygote, are described. The ongoing descriptive and functional examinations of DNA methylation in the relevant biological samples, in conjugation with analyses of non-coding RNA and histone modifications, hold promise for improved delineation of the effect size and mechanistic background for epigenetic inheritance of metabolic diseases.

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Yachao Zhang, Jieqiong Yang, Shijian Lv, Dong-Qin Zhao, Zi-Jiang Chen, Wei-Ping Li, and Cong Zhang

Preeclampsia (PE) is a pregnancy-induced disorder characterized by hypertension and proteinuria after 20 weeks of gestation, affecting 5–7% of pregnancies worldwide. So far, the etiology of PE remains poorly understood. Abnormal decidualization is thought to contribute to the development of PE. SP1 belongs to the Sp/KLF superfamily and can recruit P300 to regulate the transcription of several genes. SP1 is also very important for decidualization as it enhances the expression of tissue factor. In this study, we investigated the expression of SP1 and P300 in deciduae and their relationship with PE. A total of 42 decidua samples were collected, of which 21 were from normal pregnant (NP) and 21 from severe PE. SP1 and P300 expression in deciduae and the levels of SP1 and P300 in cultured human endometrial stromal cells (hESCs) and primary hESCs during decidualization were determined. To further investigate the role of SP1 and P300 in human decidualization, RNA interference was used to silence SP1 and P300 in hESCs and primary hESCs. The following results were obtained. We found that the expressions of SP1 and P300 were reduced in decidual tissues with PE compared to those from NP. In the in vitro model of induction of decidualization, we found an increase in both SP1 and P300 levels. Silencing of SP1 and P300 resulted in abnormal decidualization and a significant reduction of decidualization markers such as insulin-like growth factor-binding protein1 and prolactin. Furthermore, the expression of vascular endothelial growth factor was also decreased upon SP1 and P300 silencing. Similar results were observed in primary hESCs. Our results suggest that SP1 and P300 play an important role during decidualization. Dysfunction of SP1 and P300 leads to impaired decidualization and might contribute to PE.

Open access

Marc Simard, Caroline Underhill, and Geoffrey L Hammond

Corticosteroid-binding globulin (CBG) is a plasma carrier of glucocorticoids. Human and rat CBGs have six N-glycosylation sites. Glycosylation of human CBG influences its steroid-binding activity, and there are N-glycosylation sites in the reactive center loops (RCLs) of human and rat CBGs. Proteolysis of the RCL of human CBG causes a structural change that disrupts steroid binding. We now show that mutations of conserved N-glycosylation sites at N238 in human CBG and N230 in rat CBG disrupt steroid binding. Inhibiting glycosylation by tunicamycin also markedly reduced human and rat CBG steroid-binding activities. Deglycosylation of fully glycosylated human CBG or human CBG with only one N-glycan at N238 with Endo H-reduced steroid-binding affinity, while PNGase F-mediated deglycosylation does not, indicating that steroid binding is preserved by deamidation of N238 when its N-glycan is removed. When expressed in N-acetylglucosaminyltransferase-I-deficient Lec1 cells, human and rat CBGs, and a human CBG mutant with only one glycosylation site at N238, have higher (2–4 fold) steroid-binding affinities than when produced by sialylation-deficient Lec2 cells or glycosylation-competent CHO-S cells. Thus, the presence and composition of an N-glycan in this conserved position both appear to influence the steroid binding of CBG. We also demonstrate that neutrophil elastase cleaves the RCL of human CBG and reduces its steroid-binding capacity more efficiently than does chymotrypsin or the Pseudomonas aeruginosa protease LasB. Moreover, while glycosylation of N347 in the RCL limits these activities, N-glycans at other sites also appear to protect CBG from neutrophil elastase or chymotrypsin.

Free access

Heather C Denroche and C Bruce Verchere

Islet amyloid polypeptide (IAPP), the main component of islet amyloid in type 2 diabetes and islet transplants, is now recognized as a contributor to beta cell dysfunction. Increasingly, evidence warrants its investigation in type 1 diabetes owing to both its immunomodulatory and metabolic actions. Autoreactive T cells to IAPP-derived epitopes have been described in humans, suggesting that IAPP is an islet autoantigen in type 1 diabetes. In addition, although aggregates of IAPP have not been implicated in type 1 diabetes, they are potent pro-inflammatory stimuli to innate immune cells, and thus, could influence autoimmunity. IAPP aggregates also occur rapidly in transplanted islets and likely contribute to islet transplant failure in type 1 diabetes through sterile inflammation. In addition, since type 1 diabetes is a disease of both insulin and IAPP deficiency, clinical trials have examined the potential benefits of IAPP replacement in type 1 diabetes with the injectable IAPP analogue, pramlintide. Pramlintide limits postprandial hyperglycemia by delaying gastric emptying and suppressing hyperglucagonemia, underlining the possible role of IAPP in postprandial glucose metabolism. Here, we review IAPP in the context of type 1 diabetes: from its potential involvement in type 1 diabetes pathogenesis, through its role in glucose metabolism and use of IAPP analogues as therapeutics, to its potential role in clinical islet transplant failure and considerations in this regard for future beta cell replacement strategies.

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Amadeo Muñoz Garcia, Martina Kutmon, Lars Eijssen, Martin Hewison, Chris T Evelo, and Susan L Coort

Unbiased genomic screening analyses have highlighted novel immunomodulatory properties of the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D). However, clearer interpretation of the resulting gene expression data is limited by cell model specificity. The aim of the current study was to provide a broader perspective on common gene regulatory pathways associated with innate immune responses to 1,25(OH)2D, through systematic re-interrogation of existing gene expression databases from multiple related monocyte models (the THP-1 monocytic cell line (THP-1), monocyte-derived dendritic cells (DCs) and monocytes). Vitamin D receptor (VDR) expression is common to multiple immune cell types, and thus, pathway analysis of gene expression using data from multiple related models provides an inclusive perspective on the immunomodulatory impact of vitamin D. A bioinformatic workflow incorporating pathway analysis using PathVisio and WikiPathways was utilized to compare each set of gene expression data based on pathway-level context. Using this strategy, pathways related to the TCA cycle, oxidative phosphorylation and ATP synthesis and metabolism were shown to be significantly regulated by 1,25(OH)2D in each of the repository models (Z-scores 3.52–8.22). Common regulation by 1,25(OH)2D was also observed for pathways associated with apoptosis and the regulation of apoptosis (Z-scores 2.49–3.81). In contrast to the primary culture DC and monocyte models, the THP-1 myelomonocytic cell line showed strong regulation of pathways associated with cell proliferation and DNA replication (Z-scores 6.1–12.6). In short, data presented here support a fundamental role for active 1,25(OH)2D as a pivotal regulator of immunometabolism.

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Martina Holubová, Lucie Hrubá, Barbora Neprašová, Zuzana Majerčíková, Zdeňka Lacinová, Jaroslav Kuneš, Lenka Maletínská, and Blanka Železná

The situation following anti-obesity drug termination is rarely investigated, eventhough a decrease in body weight needs to be sustained. Therefore, this study examined the impact of twice-daily peripheral administration of 5 mg/kg [N-palm-γGlu-Lys11] prolactin-releasing peptide 31 (palm11-PrRP31) in mice with diet-induced obesity (DIO from consuming a high-fat diet) after 28 days of treatment (palm11-PrRP31 group) and after 14 days of peptide treatment followed by 14 days of discontinuation (palm11-PrRP31 + saline group). At the end of the treatment, cumulative food intake, body weight and subcutaneous fat weight/body weight ratio and leptin plasma level were reduced significantly in both the palm11-PrRP31 group and the palm11-PrRP31 + saline group compared to the saline control group. This reduction correlated with significantly increased FOSB, a marker of long-term neuronal potentiation, in the nucleus arcuatus and nucleus tractus solitarii, areas known to be affected by the anorexigenic effect of palm11-PrRP31. Moreover, activation of leptin-related hypothalamic signaling was registered through an increase in phosphoinositide-3-kinase, increased phosphorylation of protein kinase B (PKB, AKT) and enhanced extracellular signal-regulated kinase 1/2 phosphorylation. Besides, lowered apoptotic markers c-JUN N-terminal kinase and c-JUN phosphorylation were registered in the hypothalami of both palm11-PrRP31-treated groups. This study demonstrates that palm11-PrRP31 positively affects feeding and leptin-related hypothalamic signaling, not only after 28 days of treatment but even 14 days after the termination of a 14-day long treatment without the yo-yo effect.

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Yabing Mi, Wangsheng Wang, Jiangwen Lu, Chuyue Zhang, Yawei Wang, Hao Ying, and Kang Sun

Rupture of fetal membranes (ROM) can initiate parturition at both term and preterm. Collagen III in the compact layer of the amnion contributes to the tensile strength of fetal membranes. However, the upstream signals triggering collagen III degradation remain mostly elusive. In this study, we investigated the role of cortisol regenerated by 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) in collagen III degradation in human amnion fibroblasts with an aim to seek novel targets for the prevention of preterm premature ROM (pPROM)-elicited preterm birth. Human amnion tissue and cultured amnion tissue explants and amnion fibroblasts were used to study the regulation of collagen III, which is composed of three identical 3α 1 chains (COL3A1), by cortisol. Cortisol decreased COL3A1 protein but not mRNA abundance in a concentration-dependent manner. Cortisone also decreased COL3A1 protein, which was blocked by 11β-HSD1 inhibition. The reduction in COL3A1 protein by cortisol was not affected by a transcription inhibitor but was further enhanced by a translation inhibitor. Autophagic pathway inhibitor chloroquine or siRNA-mediated knock-down of ATG7, an essential protein for autophagy, failed to block cortisol-induced reduction in COL3A1 protein abundance, whereas proteasome pathway inhibitors MG132 and bortezomib significantly attenuated cortisol-induced reduction in COL3A1 protein abundance. Moreover, cortisol increased COL3A1 ubiquitination and the reduction of COL3A1 protein by cortisol was blocked by PYR-41, a ubiquitin-activating enzyme inhibitor. Conclusively, cortisol regenerated in amnion fibroblasts may be associated with ROM at parturition by reducing collagen III protein abundance through a ubiquitin-proteasome pathway.