Spatiotemporal modulation of nitric oxide and Notch signaling by hemodynamic-responsive Trpv4 is essential for ventricle regeneration.

Zebrafish have a remarkable ability to regenerate injured hearts. Altered hemodynamic forces after larval ventricle ablation activate the endocardial Klf2a-Notch signaling cascade to direct zebrafish cardiac regeneration. However, how the heart perceives blood flow changes and initiates signaling pathways promoting regeneration is not fully understood. The present study demonstrated that the mechanosensitive channel Trpv4 sensed the altered hemodynamic forces in injured hearts and its expression was regulated by blood flow. In addition to mediating the endocardial Klf2a-Notch signal cascade around the atrioventricular canal (AVC), we discovered that Trpv4 regulated nitric oxide (NO) signaling in the bulbus arteriosus (BA). Further experiments indicated that Notch signaling primarily acted at the early stage of regeneration, and the major role of NO signaling was at the late stage and through TGF-ß pathway. Overall, our findings revealed that mechanosensitive channels perceived the changes in hemodynamics after ventricle injury, and provide novel insights into the temporal and spatial coordination of multiple signaling pathways regulating heart regeneration.

Upconversion luminescence nanosensor for detection of Fe3+ and phosphate ion based on the inner-filter effect.

In this work, an upconversion luminescence (UCL) nanosensor for fast detection of ferric ion (Fe3+) and phosphate ion (Pi) is developed based on the inner-filter effect (IFE) between NaYF4:Yb/Er upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex. Fe3+-HB complex has strong absorption band (450-650 nm), which overlaps with the green emission peak of UCNPs at 545 nm. By adding Fe3+ and Pi, the UCNPs-HB system produces the red-shift change of absorption spectrum, which leads to the "on-off-on" process of IFE. So, with the specific recognition ability of HB for Fe3+ and the competitive complexation of Pi for Fe3+, the proposed nanosensor utilizes the UCL change to achieve the detection of the targets. For the detections of Fe3+, the linear range is 10-600 µM with a limit of detection (LOD) of 2.62 µM, and for Pi, the linear range is 5-100 µM with a LOD of 1.25 µM. The results for selectivity, precision, and recovery test are also satisfactory. Furthermore, the real sample detection shows that the proposed nanaosensor has a great potential in environmental and biological systems. An upconversion luminescence (UCL) nanosensor based on the inner-filter effect (IFE) between upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex for the detection of Fe3+ and phosphate ion has been proposed, which is promising to be a convenient and sensitive assay for monitoring Fe3+ and phosphate ion in different environments and biological systems.

A nanobody targeting the LIN28:let-7 interaction fragment of TUT4 blocks uridylation of let-7.

The LIN28:pre-let-7:TUTase ternary complex regulates pluripotency and oncogenesis by controlling processing of the let-7 family of microRNAs. The complex oligouridylates the 3' ends of pre-let-7 molecules, leading to their degradation via the DIS3L2 exonuclease. Previous studies suggest that components of this complex are potential therapeutic targets in malignancies that aberrantly express LIN28. In this study we developed a functional epitope selection approach to identify nanobody inhibitors of the LIN28:pre-let-7:TUT4 complex. We demonstrate that one of the identified nanobodies, Nb-S2A4, targets the 106-residue LIN28:let-7 interaction (LLI) fragment of TUT4. Nb-S2A4 can effectively inhibit oligouridylation and monouridylation of pre-let-7g in vitro. Expressing Nb-S2A4 allows maturation of the let-7 species in cells expressing LIN28, highlighting the therapeutic potential of targeting the LLI fragment.

Unlabelled LRET biosensor based on double-stranded DNA for the detection of anthraquinone anticancer drugs.

Based on upconversion nanoparticles (UCNPs) as energy donor and herring sperm DNA (hsDNA) as molecular recognition element, an unlabelled upconversion luminescence (UCL) affinity biosensor was constructed for the detection of anthraquinone (AQ) anticancer drugs in biological fluids. AQ anticancer drugs can insert into the double helix structure of hsDNA on the surface of UCNPs, thereby shortening the distance from UCNPs. Therefore, the luminescence resonance energy transfer (LRET) phenomenon is effectively triggered between UCNPs and AQ anticancer drugs. Hence, AQ anticancer drugs can be quantitatively detected according to the UCL quenching rate. The biosensor showed good sensitivity and stability for the detection of daunorubicin (DNR) and doxorubicin (ADM). For the detection of DNR, the linear range is 1-100 µg·mL-1 with a limit of detection (LOD) of 0.60 µg·mL-1, and for ADM, the linear range is 0.5-100 µg·mL-1 with a LOD of 0.38 µg·mL-1. The proposed biosensor provides a convenient method for monitoring AQ anticancer drugs in clinical biological fluids in the future.

Neutrophil side fluorescence: a new indicator for predicting the severity of patients with bronchiectasis.

BACKGROUND: Neutrophilic inflammation in the airway is a hallmark of bronchiectasis. Neutrophil extracellular traps (NETs) have been reported to play an important role in the occurrence and development of bronchiectasis. Neutrophil side fluorescence is one of the characteristics of neutrophils that can reflect the activation of neutrophils and the formation of NETs. OBJECTIVE: To explore the relationship between the values of neutrophil side fluorescence (NEUT-SFL) in the peripheral blood of bronchiectasis patients, and the severity of the disease. METHODS: 82 patients with bronchiectasis from the Department of Respiratory and Critical Medicine, at the Third Affiliated Hospital of Southern Medical University and were scored with Bronchiectasis Severity Index (BSI) (2019-2021). The clinical data such as the value of NEUT-SFL, neutrophil count, C-reactive protein, and procalcitonin levels were collected and retrospectively analyzed. NEUT-SFL values neutrophil count from 28 healthy subjects were also used to ascertain cut-off values. RESULTS: Based on the BSI scores, patients were divided into three categories as mild (32%), moderate (29%), and severe (39%). Our results showed that the values of NEUT-SFL were higher in bronchiectasis patients compared to healthy controls. The levels of NEUT-SFL positively correlated with the high BSI scores in patients (P = 0.037, r = 0.23) and negatively correlated with the lung function in these patients (r = - 0.35, P = 0.001). The area under the ROC curve was 0.813, the best cut-off was 42.145, indicating that NEUT-SFL values > 42.145 can potentially predict the severity of bronchiectasis. CONCLUSIONS: The values of NEUT-SFL in the peripheral blood can be used for predicting the severity of bronchiectasis.

Upconversion luminescence-based aptasensor for the detection of thyroid-stimulating hormone in serum.

Thyroid-stimulating hormone (TSH) plays a crucial physiological and pathological role in humans, and a timely and sensitive detection of TSH is critical for early diagnosis and prevention of thyroid-related diseases. Herein, we developed a simple wash-free biological aptasensor based on luminescence resonance energy transfer (LRET) between NaYF4:Yb,Er upconversion nanoparticles (UCNPs) and tetramethylrhodamine (TAMRA) for the detection of TSH with high sensitivity. In this LRET system, UCNPs as donors and TAMRA as receptors were modified with nucleic acid aptamers Apt-1 and Apt-2, respectively. When TSH was present, the two aptamer strands both specifically recognized TSH to form a hairpin-like structure, thereby shortening the space between UCNPs and TAMRA. The LRET occurred under radiation of 980-nm light. By detecting the change of upconversion luminescence (UCL) intensity (I545nm), the activity of TSH was quantified. The resulting detection dynamic range and the limit of detection were 0.1-5.0 mIU·L-1 and 0.065 mIU·L-1, respectively. The aptasensor using UCNPs as LRET donors was capable of effectively eliminating the background interference of a complicated biological environment, and showed good specificity because of the excellent recognition function of aptamers. Due to high sensitivity, easiness of fabrication, operational convenience, and selectivity, the UCL-based aptasensor is a promising candidate for clinical TSH determination. Based on nucleic acid aptamer and the mechanism of luminescence resonance energy transfer (LRET) between upconversion nanoparticles (UCNPs) donor and tetramethylrhodamine (TAMRA) receptor, an aptasensor was constructed for the quantitative analysis of TSH activity in serum by testing the change of I545nm.

Type I interferon response-related microglial Mef2c deregulation at the onset of Alzheimer's pathology in 5×FAD mice.

Alzheimer's disease (AD) is a chronic neurodegenerative disorder with multifactorial etiology. The role of microglia in the pathogenesis of AD has been increasingly recognized in recent years; however, the detailed mechanisms shaping microglial phenotypes in AD-relevant pathological settings remain largely unresolved. Myocyte-specific enhancer factor 2C (Mef2C) is a transcription factor with versatile functions. Recent studies have attributed aging-related microglial changes to type I interferon (IFN-I)-associated Mef2C deregulation. In view of the close relationship between brain aging and AD, it is of great interest to determine microglial Mef2C changes in AD-related conditions. In this study, we have found that suppressed Mef2C nuclear translocation was an early and prominent microglial phenotype in a mouse model of brain amyloidosis (5×FAD mice), which exacerbated with age. Echoing the early Mef2C deregulation and its association with microglial activation, transcriptional data showed elicited IFN-I response in microglia from young 5×FAD mice. Amyloid beta 42 (Aß42) in its oligomeric forms promoted Mef2C deregulation in microglia on acute organotypic brain slices with augmented microglial activation and synapse elimination via microglial phagocytosis. Importantly, these oligomeric Aß42-mediated microglial changes were substantially attenuated by blocking IFN-I signaling. The simplest interpretation of the results is that Mef2C, concurring with activated IFN-I signaling, constitutes early microglial changes in AD-related conditions. In addition to the potential contribution of Mef2C deregulation to the development of microglial phenotypes in AD, Mef2C suppression in microglia may serve as a potential mechanistic pathway linking brain aging and AD.

Thyroid-stimulating hormone decreases the risk of osteoporosis by regulating osteoblast proliferation and differentiation.

BACKGROUND: As the incidence of secretory osteoporosis has increased, bone loss, osteoporosis and their relationships with thyroid-stimulating hormone (TSH) have received increased attention. In this study, the role of TSH in bone metabolism and its possible underlying mechanisms were investigated. METHODS: We analyzed the serum levels of free triiodothyronine (FT3), free thyroxine (FT4), and TSH and the bone mineral density (BMD) levels of 114 men with normal thyroid function. In addition, osteoblasts from rat calvarial samples were treated with different doses of TSH for different lengths of time. The related gene and protein expression levels were investigated. RESULTS: A comparison of the BMD between the high-level and low-level serum TSH groups showed that the TSH serum concentration was positively correlated with BMD. TSH at concentrations of 10 mU/mL and 100 mU/mL significantly increased the mRNA levels of ALP, COI1 and Runx2 compared with those of the control (P < 0.05, P < 0.01). Bone morphogenetic protein (BMP)2 activity was enhanced with both increased TSH concentration and increased time. The protein levels of Runx2 and osterix were increased in a dose-dependent manner. CONCLUSIONS: The circulating concentrations of TSH and BMD were positively correlated with normal thyroid function in males. TSH promoted osteoblast proliferation and differentiation in rat primary osteoblasts.

HC diet inhibited testosterone synthesis by activating endoplasmic reticulum stress in testicular Leydig cells.

Emerging epidemiological studies indicate that hypercholesterolaemia is a risk factor for testosterone deficiency. However, the underlying mechanism is unclear. Testicular Leydig cells are the primary source of testosterone in males. To identify the effect and mechanism of cholesterol overload on Leydig cell function, rats were fed with a HC (HC) diet to induce hypercholesterolaemia. During the 16-week feeding period, serum testosterone levels were reduced in a time-dependent manner in rats fed the HC diet. Accordingly, these steroidogenic enzymes within the Leydig cells, including steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage cytochrome P450 (P450scc) and 3ß-hydroxysteroid dehydrogenase (3ß-HSD), were down-regulated. Notably, the HC-fed rats showed evident endoplasmic reticulum (ER) stress in the testis, including a dilated ER as an evident pathological change in the Leydig cell ultrastructure, up-regulated ER stress biomarker (binding immunoglobulin protein) levels and activation of the activating transcription factor 6 (ATF6)-related unfolded protein response pathway. Further analysis showed that when 4-phenyl butyric acid (4-PBA) was used to block ER stress in HC-fed rats for 8 weeks, the testosterone deficiency was significantly alleviated. Our findings suggested that high dietary cholesterol intake affected serum testosterone levels by down-regulating steroidogenic enzymes and that activated ER stress might serve as the underlying mechanism.

Cyclophilin D participates in the inhibitory effect of high-fat diet on the expression of steroidogenic acute regulatory protein.

OBJECTIVE: The high-fat diet (HFD)-induced obesity is responsible for the testosterone deficiency (TD). However, the mechanism remains unknown. Mitochondrial homeostasis is proved to be important for maintaining the function of steroidogenic acute regulatory protein (StAR), the first rate-limiting enzyme in testosterone synthesis. As the key regulator of mitochondrial membrane permeability, cyclophilin D (CypD) plays a crucial role in maintaining mitochondrial function. In this study, we sought to elucidate the role of CypD in the expression of StAR affected by HFD. METHODS: To analyse the influence of CypD on StAR in vivo and in vitro, mouse models of HFD, CypD overexpression and CypD knockout (Ppif-/- ) as well as Leydig cells treated with palmitic acid (PA) and CypD overexpression plasmids were examined with an array of metabolic, mitochondrial function and molecular assays. RESULTS: Compared with the normal diet mice, consistent with reduced testosterone in testes, the expressions of StAR in both mRNA and protein levels in HFD mice were down-regulated, while expressions of CypD were up-regulated. High-fat intake impaired mitochondrial function with the decrease in StAR in Leydig cells. Overexpression of CypD inhibited StAR expressions in vivo and in vitro. Compared with C57BL/6 mice with HFD, expressions of StAR were improved in Ppif-/- mice with HFD. CONCLUSIONS: Mitochondrial CypD involved in the inhibitory effect of HFD on StAR expression in testes.

Cyclophilin D deficiency attenuates mitochondrial perturbation and ameliorates hepatic steatosis.

Physiological opening of the mitochondrial permeability transition pore (mPTP) is indispensable for maintaining mitochondrial function and cell homeostasis, but the role of the mPTP and its initial factor, cyclophilin D (CypD), in hepatic steatosis is unclear. Here, we demonstrate that excess mPTP opening is mediated by an increase of CypD expression induced hepatic mitochondrial dysfunction. Notably, such mitochondrial perturbation occurred before detectable triglyceride accumulation in the liver of high-fat diet-fed mice. Moreover, either genetic knockout or pharmacological inhibition of CypD could ameliorate mitochondrial dysfunction, including excess mPTP opening and stress, and down-regulate the transcription of sterol regulatory element-binding protein-1c, a key factor of lipogenesis. In contrast, the hepatic steatosis in adenoviral overexpression of CypD-infected mice was aggravated relative to the control group. Blocking p38 mitogen-activated protein kinase or liver-specific Ire1α knockout could resist CypD-induced sterol regulatory element-binding protein-1c expression and steatosis. Importantly, CypD inhibitor applied prior to or after the onset of triglyceride deposition substantially prevented or ameliorated fatty liver. CONCLUSION: CypD stimulates mPTP excessive opening, subsequently causing endoplasmic reticulum stress through p38 mitogen-activated protein kinase activation, and results in enhanced sterol regulatory element-binding protein-1c transcription and hepatic steatosis. (Hepatology 2018;68:62-77).

The Effect of Statins on Levels of Dehydroepiandrosterone (DHEA) in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis.

BACKGROUND Currently, statins are used to treat polycystic ovary syndrome (PCOS). This systematic review and meta-analysis aimed to investigate the effect of statins on serum or plasma levels of dehydroepiandrosterone (DHEA) in women with PCOS. MATERIAL AND METHODS Databases that were searched included PubMed, Embase, and the Cochrane Library from their inception to August of 2018. Published randomized controlled trials (RCTs) were identified that evaluated the impact of statins on plasma DHEA levels in women with PCOS. The Cochrane risk of bias tool was used to assess the quality of the included RCTs. A random-effects model was used to analyze the pooled results. RESULTS Meta-analysis was performed on data from ten published studies that included 735 patients and showed that statin treatment could significantly reduce plasma DHEA levels when compared with controls (SMD, -0.43; 95% CI, -0.81-0.06; p=0.02; I²=82%). Statins were significantly more effective than placebo in reducing the levels of DHEAs. Subgroup analysis based on statin type showed that atorvastatin significantly reduced DHEA levels (SMD, -0.63; 95% CI, -1.20 - -0.05; p=0.03; I²=38%) but simvastatin did not significantly reduce DHEA levels (SMD: -0.14; 95% CI, -0.49-0.28; p=0.43; I²=77%). Subgroup analysis based on duration of treatment showed no significant difference between 12 weeks of statin treatment (SMD, -0.61; 95% CI, -1.23-0.02; p=0.06; I²=85%) and 24 weeks (SMD, -0.34; 95% CI -0.95-0.28; p=0.29; I²=83%). CONCLUSIONS Meta-analysis showed that statins significantly reduced the levels of DHEA when compared with placebo in patients with PCOS.

A prospective study of salvational intervention with ICS/LABA for reducing chronic obstructive pulmonary disease exacerbation under severe air pollution (SIRCAP) in Beijing: protocol of a multi-center randomized controlled trial.

BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) is a major cause of morbidity and mortality all over the world. Acute exacerbation of COPD (AECOPD) not only accelerates the progression of disease, but also causes hospital administration and death events. Epidemiologic studies have shown air pollution is a high risk factor of AECOPD. However, there are rare technics or treatment strategies recommended to reduce severe air pollution related AECOPD. METHODS: This is a multi-center, prospective, randomized and standard treatment parallel control clinical trial. Seven hundred sixty-four stable COPD patients in group B, C and D according to GOLD 2017 will be recruited and equally divided into two parallel groups, salvational intervention (SI group) and control group (CT group). Original treatments for participants include tiotropium (18µg once q.d), budesonide/formoterol (160µg/4.5µg once or twice b.i.d) or budesonide/formoterol (160µg/4.5µg once or twice b.i.d) with tiotropium (18µg once q.d). The savational intervention for SI group is routine treatment plus budesonide/formoterol (160µg/4.5µg once b.i.d) from the first day after severe air pollution (air quality index, AQI ≥200) to the third day after AQI < 200. CT group will maintain the original treatment. The intervention will last for 2 years. Primary outcome is the frequency of AECOPD per year and the secondary outcomes include the incidence of unplanned outpatient visits, emergency visits, hospitalization, medical cost and mortality associated with AECOPD per year. DISCUSSION: The salvational intervention is a novel strategy for COPD management under severe air pollution. Results of the present study will provide reference information to guide clinical practice in reducing the air pollution related exacerbation of COPD. TRIAL REGISTRATION: This study has been registered at www.ClinicalTrials.gov (registration identifier: NCT03083067 ) in 17 March, 2017.

The application of polypropylene mesh for testicular prosthesis in surgical castration for patients with prostate cancer.

BACKGROUND: To explore whether a polypropylene mesh is suitable for application as a new material for testicular prostheses. METHODS: The data of 65 patients with advanced prostate cancer who underwent surgical castration in hospital were collected and analyzed. Patients who preferred to undergo traditional orchidectomy (n = 16) were assigned to the control group, and patients who underwent subcapsular orchiectomy plus implantation of a polypropylene mesh testicular prosthesis (n = 49) were assigned to the experimental group. The presence of hematoma, infection, and other complications in patients in these two groups were investigated at 3 and 12 months following the surgery. The patients were also followed up using a self-designed testicular castration satisfaction questionnaire. RESULTS: A higher score indicated greater satisfaction. The mean score was 15.33 ± 2.85 in the experimental group and 4.63 ± 1.45 in the control group at 3 months after the surgery. The mean score was 14.92 ± 1.74 in the experimental group and 4.25 ± 1.61 in the control group at 12 months after the surgery. The difference between the two groups was statistically significant at the two time points (P < 0.01). CONCLUSIONS: Compared with orchidectomy alone, patients were more satisfied with subcapsular orchiectomy plus the implantation of a polypropylene mesh testicular prosthesis for the treatment of advanced prostate cancer. Furthermore, the polypropylene mesh testicular prosthesis maintained its original character over the duration of the study, with a good long-term effect. Thus, implantation of a polypropylene mesh testicular prosthesis is indicated to be safe and effective, and polypropylene mesh is potentially useful as a new material for testicular prostheses.

Follicle-stimulating hormone enhances hepatic gluconeogenesis by GRK2-mediated AMPK hyperphosphorylation at Ser485 in mice.

AIMS/HYPOTHESIS: Increased serum follicle-stimulating hormone (FSH) is correlated with fasting hyperglycaemia. However, the underlying mechanism remains unclear. Because excessive hepatic gluconeogenesis is a major cause of fasting hyperglycaemia the present study investigated whether FSH increases hepatic gluconeogenesis in mice. METHODS: Ovariectomised mice supplemented with oestradiol (E2) to maintain normal levels of serum E2 (OVX+E2 mice) were injected with low or high doses of FSH. We knocked out Crtc2, a crucial factor in gluconeogenesis, and Fshr to discern their involvement in FSH signalling. To evaluate the role of the G-protein-coupled receptor (GPCR) kinase 2 (GRK2), which could affect glucose metabolism and interact directly with non-GPCR components, a specific GRK2 inhibitor was used. The pyruvate tolerance test (PTT), quantification of PEPCK and glucose-6-phosphatase (G6Pase), key enzymes of gluconeogenesis, GRK2 and phosphorylation of AMP-activated protein kinase (AMPK) were examined to evaluate the level of gluconeogenesis in the liver. A nonphosphorylatable mutant of AMPK Ser485 (AMPK S485A) was transfected into HepG2 cells to evaluate the role of AMPK Ser485 phosphorylation. RESULTS: FSH increased fasting glucose (OVX+E2+high-dose FSH 8.18 ± 0.60 mmol/l vs OVX+E2 6.23 ± 1.33 mmol/l), the PTT results, and the transcription of Pepck (also known as Pck1; 2.0-fold increase) and G6pase (also known as G6pc; 2.5-fold increase) in OVX+E2 mice. FSH also enhanced the promoter luciferase activities of the two enzymes in HepG2 cells. FSH promoted the membrane translocation of GRK2, which is associated with increased AMPK Ser485 and decreased AMPK Thr172 phosphorylation, and enhanced the nuclear translocation of cyclic AMP-regulated transcriptional coactivator 2 (CRTC2). GRK2 could bind with AMPK and induce Ser485 hyperphosphorylation. Furthermore, either the GRK2 inhibitor or AMPK S485A blocked FSH-regulated AMPK Thr172 dephosphorylation and gluconeogenesis. Additionally, the deletion of Crtc2 or Fshr abolished the function of FSH in OVX+E2 mice. CONCLUSIONS/INTERPRETATION: The results indicate that FSH enhances CRTC2-mediated gluconeogenesis dependent on AMPK Ser485 phosphorylation via GRK2 in the liver, suggesting an essential role of FSH in the pathogenesis of fasting hyperglycaemia.

PMLIV overexpression promotes TGF-ß-associated epithelial-mesenchymal transition and migration in MCF-7 cancer cells.

The epithelial-mesenchymal transition (EMT) is a key event associated with metastasis and dissemination in breast tumor pathogenesis. Promyelocytic leukemia (PML) gene produces several isoforms due to alternative splicing; however, the biological function of each specific isoform has yet to be identified. In this study, we report a previously unknown role for PMLIV, the most intensely studied nuclear isoform, in transforming growth factor-ß (TGF-ß) signaling-associated EMT and migration in breast cancer. This study demonstrates that PMLIV overexpression promotes a more aggressive mesenchymal phenotype and increases the migration of MCF-7 cancer cells. This event is associated with activation of the TGF-ß canonical signaling pathway through the induction of Smad2/3 phosphorylation and the translocation of phospho-Smad2/3 to the nucleus. In this study, we report a previously unknown role for PMLIV in TGF-ß signaling-induced regulation of breast cancer-associated EMT and migration. Targeting this pathway may be therapeutically beneficial.

Ablation of prolactin receptor increases hepatic triglyceride accumulation.

Increasing prevalence of non-alcoholic fatty liver disease (NAFLD) worldwide has necessitated a more thorough understanding of it and expanded the scope of research in this field. Women are more resistant to NAFLD than men despite equal exposure to major risk factors, such as obesity or hyperlipidemia. Female resistance is hormone-dependent, as evidenced by the sharp increase in NAFLD incidence in post-menopausal women who do not take hormone replacement therapy. Here, we found that the estrogen-responsive pituitary hormone prolactin (PRL), through specific PRL receptor (PRLR), down-regulates hepatic triglyceride (TG) accumulation. PRL was demonstrated to significantly down-regulate hepatic TG accumulation in female mice and protect male mice from liver steatosis induced by high-fat diet. Interestingly, Ad-shPRLR injected mice, whose hepatic PRLR abundance was effectively decreased at the protein levels, exhibited significantly aggravated liver steatosis. PRL could decrease the expression of stearoyl-coenzyme A desaturase 1 (SCD1), the rate-limiting enzyme in the biosynthesis of monounsaturated fatty acids, in animal models and multiple hepatic cell lines. Following knockdown of PRLR, the changes to PRL-triggered SCD1 expression disappeared. Thus, PRL acted as a previously unrecognized master regulator of liver TG metabolism, indicating that modification of PRL via PRLR might serve as a potential therapeutic target for NAFLD.

A novel role for CRTC2 in hepatic cholesterol synthesis through SREBP-2.

Cholesterol synthesis is regulated by the transcription factor sterol regulatory element binding protein 2 (SREBP-2) and its target gene 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), which is the rate-limiting enzyme in cholesterol synthesis. Cyclic adenosine monophosphate-responsive element (CRE) binding protein-regulated transcription coactivator (CRTC) 2 is the master regulator of glucose metabolism. However, the effect of CRTC2 on cholesterol and its potential molecular mechanism remain unclear. Here, we demonstrated that CRTC2 expression and liver cholesterol content were increased in patients with high serum cholesterol levels who underwent resection of liver hemangiomas, as well as in mice fed a 4% cholesterol diet. Mice with adenovirus-mediated CRTC2 overexpression also showed elevated lipid levels in both serum and liver tissues. Intriguingly, hepatic de novo cholesterol synthesis was markedly increased under these conditions. In contrast, CRTC2 ablation in mice fed a 4% cholesterol diet (18 weeks) showed decreased lipid levels in serum and liver tissues compared with those in littermate wild-type mice. The expression of lipogenic genes (SREBP-2 and HMGCR) was consistent with hepatic CRTC2 levels. In vivo imaging showed enhanced adenovirus-mediated HMGCR-luciferase activity in adenovirus-mediated CRTC2 mouse livers; however, the activity was attenuated after mutation of CRE or sterol regulatory element sequences in the HMGCR reporter construct. The effect of CRTC2 on HMGCR in mouse livers was alleviated upon SREBP-2 knockdown. CRTC2 modulated SREBP-2 transcription by CRE binding protein, which recognizes the half-site CRE sequence in the SREBP-2 promoter. CRTC2 reduced the nuclear protein expression of forkhead box O1 and subsequently increased SREBP-2 transcription by binding insulin response element 1, rather than insulin response element 2, in the SREBP-2 promoter. CONCLUSION: CRTC2 regulates the transcription of SREBP-2 by interfering with the recognition of insulin response element 1 in the SREBP-2 promoter by forkhead box O1, thus inducing SREBP-2/HMGCR signaling and subsequently facilitating hepatic cholesterol synthesis. (Hepatology 2017;66:481-497).

Effect of Testosterone Synthesis and Conversion on Serum Testosterone Levels in Obese Men.

Obesity is associated with decreased testosterone levels in males. Testosterone is synthesized by testosterone synthetic enzymes, which are stimulated by luteinizing hormone (LH). Testosterone can also be converted to estradiol via the aromatase. The objective of this study was to examine the factors related to testosterone synthesis and conversion, and to systematically evaluate the key processes that influence testosterone levels in male obesity. Three hundred and two male subjects (aged 25-45 years old) were divided according to BMI into normal weight (18.5-23.9 kg/m2), overweight (24-27.9 kg/m2), and obese (≥28 kg/m2) groups; or divided following WHR into non-abdominal obesity and abdominal obesity groups (WHR: ≥0.9). Male C57BL/6 mice were divided into normal diet (ND) and high-fat diet (HFD)-induced obesity group. Serum sex hormones and aromatase levels were measured using ELISAs. Testosterone synthetic enzymes in the testes were measured by qRT-PCR. The testosterone levels in obese men and abdominal obesity men were lower than normal men. In abdominal obesity men serum LH levels were decreased and associated with testosterone levels after multivariate regression analysis. Serum aromatase levels were increased in abdominal obesity males. In mice, compared to the ND group, the HFD group had decreased steroidogenic acute regulatory protein (StAR). However, aromatase levels in subcutaneous adipose tissue were higher in the ND group than HFD group. In conclusion, according to this study decreased testicular synthesis function and the conversion of testosterone may explain the reduction in testosterone levels in male obesity, and the decrease of testicular synthesis may change first.

The Effect of Aromatase on the Reproductive Function of Obese Males.

Obesity has increased dramatically worldwide, which is associated with male infertility. Androgen deficiency, impaired spermatogenesis, and erectile dysfunction are characteristics of male infertility. The balance of androgens and estrogens is essential for maintaining normal reproductive function in males. Aromatase, the rate-limiting enzyme in the conversion of androgens into estrogens, is present in various tissues. The expression of aromatase is proportional to body fat mass and causes more fat accumulation, thus forming a vicious cycle. Excessive aromatase activity in adipose tissue leads to increased conversion of androgens into estrogens, eventually results in a reduction of testosterone levels and is the underlying reason for obesity-related infertility. In the male reproductive system, all testicular somatic cells and germ cells express aromatase, except for peritubular myoid cells. The results of studies regarding the effect of aromatase in testicular somatic cells and germ cells have been contradictory. The effect of estrogens in testicular somatic cells is inhibitory, leading to reduced testosterone levels and sperm production; however, it has been observed that aromatase participates in the acquisition of sperm motility. The overall effect of estrogen modulation is an inhibition of spermatogenesis. Aromatase inhibitors are an effective therapy for obesity-associated hypogonadism because they restore normal sex hormone levels and improve semen parameters. This article systematically introduces the basic knowledge of aromatase and provides information of the current advances relating to aromatase in male reproductive function. Increasing our knowledge on the role of aromatase in male obesity could help in proposing new approaches to treat infertile men.