Paclitaxel Induces the Apoptosis of Prostate Cancer Cells via ROS-Mediated HIF-1α Expression.

Prostate cancer (PCa) is the most common malignancy to endanger the health of male genitourinary system. Clinically, paclitaxel (PTX) (C47H51NO14), a diterpene alkaloid, is commonly used as an effective natural antineoplastic drug during the treatment of PCa. However, the mechanism and pathway involved in the function of PTX are poorly understood. In the current study, we employed the CCK-8 assay, revealing that PTX can inhibit the survival and induce the apoptosis of PC3M cells (a human prostate cancer cell line) in a concentration-dependent manner. Reactive oxygen species (ROS), as a metabolic intermediate produced by the mitochondrial respiratory chain, are highly accumulated under the PTX treatment, which results in a sharp decrease of the mitochondrial membrane potential in PC3M cells. Additionally, the migration and invasion of PC3M cells are weakened due to PTX treatment. Further analysis reveals that N-acetylcysteine (NAC), which functions as an antioxidant, not only rescues the decreased mitochondrial membrane potential induced by the abnormal ROS level, but also restores the migration and invasion of PC3M cells. In a subsequent exploration of the detailed mechanism, we found that hypoxia-inducible factor (HIF)-1α works as a downstream gene that can respond to the increased ROS in PC3M cells. Under PTX treatment, the expression levels of HIF-1α mRNA and protein are significantly increased, which stimulate the activation of JNK/caspase-3 signaling and promote the apoptosis of PC3M cells. In summary, we demonstrate that PTX regulates the expression of HIF-1α through increased ROS accumulation, thereby promoting the activation of JNK/caspase-3 pathway to induce the apoptosis of PCa cells. This study provides new insights into the mechanism of antineoplastic action of taxanes and unveils the clinical benefit of the ROS-HIF-1α signaling pathway, which may offer a potential therapeutic target to prevent the development of PCa.

Evolution of Subfamily I.1 Lipases in Pseudomonas aeruginosa.

The gram-negative Pseudomonas aeruginosa is an opportunistic human pathogen that contains two different types of strains: the "classical" and the "outlier". In the "classical" strain, its bacterial subfamily I.1 lipases, such as LipA and LipC in P. aeruginosa PAO1, play critical roles in its pathogenicity. However, less is known about the subfamily I.1 lipases in the "outlier" strain, nor the evolution paths of those lipases in both types of P. aeruginosa strains. Our genome-scale investigation on I.1 lipases across different bacterial strains demonstrates the presence of one LipA-like and one new type of I.1 lipase (LipC2) in those "outlier" strains. The related genomic islands analyses further suggest that the LipC counterpart gene in the "outlier" strain was lost by gene truncation. In addition, the evolutionary analyses also indicates the horizontal LipC2 gene transfer from other gammaproteobacterial species, as well as the horizontal LipA gene transfer between two different phyla, both suggesting that the gene transfer of bacterial I.1 lipases might occur in different taxonomical levels. Our results not only provide an evidence to understand the pathogenicity among different P. aeruginosa strains, but add to the knowledge of I.1 lipase evolution in bacteria.

Co-expression of Pseudomonas alcaligenes lipase and its specific foldase in Pichia pastoris by a dual expression cassette strategy.

Lipomax is a commercialized foldase-dependent Pseudomonas lipase that was previously expressed only in Pseudomonas strains. Here, using Pichia pastoris as the host, we report a new co-expression method that leads to the successful production of Lipomax. The active Lipomax is extracellularly co-expressed with its cognate foldase (LIM); and the purified enzyme mix has the optimum pH at pH 8.0 and an optimal temperature around 40 °C. N-glycosylation was observed for Pichia produced Lipomax, and its reduction was shown to increase the lipolytic activity. With different p-nitrophenyl esters as the substrates, the substrate profiling analyses further indicate that Lipomax prefers esters with middle-long chain fatty acids, showing the highest specific activity to p-nitrophenyl caprylate (C8). The extracellular co-expression of Lipomax and LIM in Pichia will not only increase our ability to investigate additional eukaryotic hosts for lipase expression, but also be of considerable value in analyzing other foldase-dependent lipases.

Activation of NF-κB signaling pathway during HCG-induced VEGF expression in luteal cells.

Vascular endothelial growth factor (VEGF) plays an essential role in luteal angiogenesis, the present study therefore utilized luteal cells cultured in vitro to further investigate the activation and contribution of nuclear factor (NF)-κB to VEGF expression induced by human chorionic gonadotrophin (HCG). The present results showed HCG induced VEGF expression as well as hypoxia-inducible factor (HIF)-1α mRNA and protein expressions, which was blocked by NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC). Further analysis found that these increases of VEGF and HIF-1α mRNA induced by HCG were also blocked by NF-κB siRNA transfection, which was consistent with PDTC treatment. However, HIF-1α siRNA treatment significantly decreased HCG induced-VEGF expression with no effect on NF-κB mRNA expression. Furthermore, combination of HIF-1α siRNA and PDTC treatment did not further decrease VEGF mRNA expression, and the result of chromatin immunoprecipitation indicated NF-κB may regulate HIF-1α transcription through binding with its promoter. Taken together, the present results clearly demonstrated that NF-κB was activated to regulate VEGF expression by increasing HIF-1α transcription in luteal cells treated with HCG. Therefore, the present study provided a new and important mechanism of luteal angiogenesis during the formation of corpus luteum in mammals.

Roles of Hypothalamic-Pituitary-Adrenal Axis and Hypothalamus-Pituitary-Ovary Axis in the Abnormal Endocrine Functions in Patients with Polycystic Ovary Syndrome.

Polycystic ovary syndrome(PCOS) is a common reproductive endocrine disease in women of childbearing age. While it can be affected by a variety of factors,its pathophysiology remains unclear. Its clinical features mainly include anovulation,hyperandrogenism,and hyperinsulinemia,which are closely related with abnormal neuroendocrine system. Hypothalamic-pituitary-gonadal axis(HPG) plays a crucial regulatory role in various life activities in mammals. In particular,hypothalamic-pituitary-adrenal(HPA) axis and hypothalamus-pituitary-ovary(HPO) axis can be abnormal in PCOS patients. The corresponding abnormalities include abnormal gonadotropin releasing hormone pulse frequency,increased luteinizing hormone/follicle-stimulating hormone ratio,and excessive excretion of adrenal and ovarian androgens. Meanwhile,insulin and leptin also play key roles in endocrine dysfunction in PCOS patients. This article systematically reviews the role of HPA axis and HPO axis in the neuroendocrine dysfunction in PCOS patients.

High fat diet triggers cell cycle arrest and excessive apoptosis of granulosa cells during the follicular development.

The regulatory mechanism of granulosa cells (GCs) proliferation during the follicular development is complicated and multifactorial, which is essential for the oocyte growth and normal ovarian functions. To investigate the role of high fat diet (HFD) on the proliferation of GCs, 4-week old female mice were fed with HFD or normal control diet (NC) for 15 weeks or 20 weeks and then detected the expression level of some regulatory molecules of cell cycle and apoptosis. The abnormal ovarian morphology was observed at 20 weeks. Further mechanistic studies indicated that HFD induced-obesity caused elevated apoptotic levels in GCs of the ovaries in a time-dependent manner. Moreover, cell cycle progress was also impacted after HFD fed. The cell cycle inhibitors, p27(Kip1) and p21(Cip1), were significantly induced in the ovaries from the mice in HFD group when compared with that in the ovaries from the mice in NC group. Subsequently, the expression levels of Cyclin D1, D3 and CDK4 were also significantly influenced in the ovaries from the mice fed with HFD in a time-dependent manner. The present results suggested that HFD induced-obesity may trigger cell cycle arrest and excessive apoptosis of GCs, causing the abnormal follicular development and ovarian function failure.

Identification of a novel small-molecule agonist for human G protein-coupled receptor 3.

G protein-coupled receptor 3 (GPR3) is an orphan G protein-coupled receptor (GPCR) predominantly expressed in mammalian brain and oocytes. GPR3 plays important roles in these two organs and is known as a Gαs-coupled receptor-activated constitutively in cells. However, the signal transduction pathway and pharmacological function of GPR3 remain unclear because of the lack of a specific ligand. By use of a human embryonic kidney 293 cell line stably expressing FLAG-GPR3-green fluorescent protein, a chemical screening for GPR3 ligands was performed using homogeneous time-resolved fluorescence cAMP assay. Diphenyleneiodonium chloride (DPI) was identified as a novel agonist of GPR3 with weak or no cross-reactivity with other GPCRs. DPI was further characterized to activate several GPR3-mediated signal transduction pathways, including Ca(2+) mobilization, cAMP accumulation, membrane recruitment of ß-arrestin2, and receptor desensitization. Parallel studies revealed that the activity of DPI is much more pronounced than sphingosine 1-phosphate, a previously reported GPR3 agonist. Our study identified a novel and specific agonist of GPR3, which provides a useful tool for further study of this orphan GPCR.

The aggregation characteristics of Aspergillus spores under various conditions and the impact on LPUV inactivation: Comparisons with chlorine-based disinfection.

Aggregation is the primary step prior to fungal biofilm development. Understanding the attributes of aggregation is of great significance to better control the emergence of waterborne fungi. In this study, the aggregation of Aspergills spores (A. flavus and A. fumigatus) under various salt, culture medium, and humic acid (HA) conditions was investigated for the first time, and the inactivation via low-pressure ultraviolet (LPUV) upon aggregated Aspergillus spores was also presented. The aggregation efficiency and size of aggregates increased over time and at low salt (NaCl and CaCl2) concentration (10 mM) while decreasing with the continuous increase of salt concentration (100 and 200 mM). Increasing the concentration of culture medium and HA promoted the aggregation of fungal spores. Spores became hydrated, swelled, and secreted more viscous substances during the growth period, which accelerated the aggregation process. Results also suggested that fungal spores aggregated more easily in actual water, posing a high risk of biohazard in real-life scenarios. Inactivation efficiency by LPUV decreased with higher aggregation degrees due to the protection from the damaged spores on the outer layer and the shielding of pigments in the cell wall. Compared to chlorine-based disinfection, the aggregation resulted in the extension of shoulder length yet neglectable change of inactivation rate constant under LPUV treatment. Further investigation of cell membrane integrity and intracellular reactive oxygen species was conducted to elucidate the difference in mechanisms between various techniques. This study provides insight into the understanding and controlling of the aggregation of fungal spores.

[Effects of phosphatidylinositol-3 kinase/protein kinase b/bone morphogenetic protein-15 pathway on the follicular development in the mammalian ovary].

In mammals, ovarian follicle is made of an oocyte with its surrounding granulosa cells and theca cells. Follicular growth and development is a highly coordinated programmable process, which guarantees the normal oocyte maturation and makes it having the fertilizing capacity. The paracrine and autocrine between oocytes and granulosa cells are essential for the follicular development to provide a suitable microenvironment. Phosphatidylinositol-3 kinase /protein kinase B is one of these important regulatory signaling pathways during this developmental process, and bone morphogenetic protein-15 an oocyte-specific secreted signal molecule, which regulates the follicular development by paracrine in the mammalian ovary. The present article overviewed the role of phosphatidylinositol-3 kinase / protein kinase B signaling during the follicular development based on our previous investigation about protein kinase B /forkhead transcription factor forkhead family of transcription factors -3a, and then focused on the regulatory effects of bone morphogenetic protein-15, as a downstream signal molecule of phosphatidylinositol-3 kinase / forkhead family of transcription factors -3a pathway, on ovarian follicular development, which helped to further understand the molecular mechanism regulating the follicular development and to treat ovarian diseases like infertility.

Therapeutic Effects and Molecular Mechanism of Chlorogenic Acid on Polycystic Ovarian Syndrome: Role of HIF-1alpha.

Chlorogenic acid (CGA) is a powerful antioxidant polyphenol molecule found in many diets and liquid beverages, playing a preventive and therapeutic role in various diseases caused by oxidative stress and inflammation. Recent research has found that CGA can not only improve clinical symptoms in PCOS patients but also improve follicular development, hormone status, and oxidative stress in PCOS rats, indicating the therapeutic effect of CGA on PCOS. Notably, our previous series of studies has demonstrated the expression changes and regulatory mechanisms of HIF-1alpha signaling in PCOS ovaries. Considering the regulatory effect of CGA on the HIF-1alpha pathway, the present article systematically elucidates the therapeutic role and molecular mechanisms of HIF-1alpha signaling during the treatment of PCOS by CGA, including follicular development, steroid synthesis, inflammatory response, oxidative stress, and insulin resistance, in order to further understand the mechanisms of CGA effects in different types of diseases and to provide a theoretical basis for further promoting CGA-rich diets and beverages simultaneously.

The physiological functions and therapeutic potential of exosomes during the development and treatment of polycystic ovary syndrome.

Polycystic ovary syndrome is a very common disease of gynecological endocrine, accompanied by irregular menstruation, hyperandrogenism, metabolic abnormalities, reproductive disorders and other clinical symptoms, which seriously endangers women's physical and mental health, but its etiology and pathogenesis are not completely clear. Recently, the contribution of exosomes to the diagnosis and treatment of various diseases in the biomedical field has attracted much attention, including PCOS. Exosomes are extracellular vesicles secreted by cells, containing various biologically active molecules such as cell-specific proteins, lipids, and nucleic acids. They are important signaling regulators in vivo and widely participate in various physiopathological processes. They are new targets for disease diagnosis and treatment. Considering the important role of non-coding RNAs during the development and treatment of PCOS, this article takes exosomal miRNAs as the breakthrough point for elucidating the physiological functions and therapeutic potential of exosomes during the development and treatment of PCOS through analyzing the effects of exosomal miRNAs on ovarian follicle development, hormone secretion, oxidative stress, inflammatory response and insulin resistance, thus providing new research directions and theoretical basis for PCOS pathogenesis, clinical diagnosis and prognosis improvement.

Natural product procyanidin B1 as an antitumor drug for effective therapy of colon cancer.

Traditional chemotherapy drugs have definite antitumor mechanisms and good therapeutic efficacy; however, their poor water solubility, serious side effects and drug resistance limit their clinical application. To the best of our knowledge, the present study reported for the first time the in vivo and in vitro anticancer effects of procyanidin B1 (PCB1), a compound that is isolated from natural sources such as grape seeds, apples, peanut skin and cranberries. Cell Counting Kit-8 assay showed that PCB1 effectively decreased the number of viable HCT-116 cells compared with cells treated with the small molecule cytotoxic drug doxorubicin. Quantitative PCR and apoptosis analysis, Cell cycle analysis, and WB analysis) of the molecular mechanism showed that PCB1 induced cell apoptosis and cell cycle arrest in S phase by increasing expression of pro-apoptosis protein caspase-3 and BAX and decreasing expression of anti-apoptosis protein Bcl-2. The efficient antitumor activity of PCB1 was demonstrated through in vivo experiments on a xenograft mouse model, demonstrating that PCB1 significantly suppressed tumor growth. The present study suggested that PCB1 represents a novel class of plant-based compounds isolated from natural sources that can be applied as an anticancer drug.

Discovery of microglia gonadotropin­releasing hormone receptor and its potential role in polycystic ovarian syndrome.

Hypothalamic inflammation is a pathophysiological basis of polycystic ovarian syndrome (PCOS), while overactivated and/or excess M1 polarized microglia are considered to be the main reason for the occurrence of hypothalamic inflammation. Therefore, in vitro and in vivo experiments were performed to assess the relationships between microglia­mediated inflammatory reactions and endocrine functions in the PCOS hypothalamus. The expression of gonadotropin­releasing hormone (GnRH) receptor (GnRHR) was demonstrated in hypothalamic microglia, and it was found that low concentration, GnRH agonist, leuprolide acetate accelerated the expression of M2 polarization marker CD206, while high concentration leuprolide acetate increased the expression of M1 polarization marker CD86 in vitro. Furthermore, aerobic exercise not only reduced the levels of serum testosterone, luteinizing hormone and GnRH and the amount of overactivated microglia, but also increased the number of M2 microglia in the hypothalamus of letrozole­induced PCOS rats. In combination, these results not only demonstrated the expression of GnRHR in hypothalamic microglia, but also demonstrated that GnRH can induce microglial polarization, while aerobic exercise may improve the microglia­mediated inflammatory reaction by reducing the expression of GnRHR in the hypothalamic microglia of PCOS rats.

Contribution of HIF-1α/BNIP3-mediated autophagy to lipid accumulation during irinotecan-induced liver injury.

Irinotecan is a topoisomerase I inhibitor which has been widely used to combat several solid tumors, whereas irinotecan therapy can induce liver injury. Liver injury generally leads to tissue hypoxia, and hypoxia-inducible factor-1α (HIF-1α), a pivotal transcription factor, mediates adaptive pathophysiological responses to lower oxygen condition. Previous studies have reported a relationship between HIF-1α and autophagy, and autophagy impairment is a common characteristic in a variety of diseases. Here, irinotecan (50 mg/kg) was employed on mice, and HepG2 and L-02 cells were cultured with irinotecan (10, 20 and 40 µM). In vivo study, we found that irinotecan treatment increased final liver index, serum aminotransferase level and hepatic lipid accumulation. Impaired autophagic flux and activation of HIF-1α/BNIP3 pathway were also demonstrated in the liver of irinotecan-treated mice. Moreover, irinotecan treatment significantly deteriorated hepatic oxidative stress, evidenced by increased MDA and ROS contents, as well as decreased GSH-Px, SOD and CAT contents. Interestingly, protein levels of NLRP3, cleaved-caspase 1 and IL-1ß were enhanced in the liver of mice injected with irinotecan. In vitro study, irinotecan-treated HepG2 and L-02 cells also showed impaired autophagic flux, while HIF-1α inhibition efficaciously removed the accumulated autophagosomes induced by irinotecan. Additionally, irinotecan treatment aggravated lipid accumulation in HepG2 and L-02 cells, and HIF-1α inhibition reversed the effect of irinotecan. Furthermore, HIF-1α inhibition weakened irinotecan-induced NLRP3 inflammasome activation in HepG2 cells. Taken together, our results suggest that irinotecan induces liver injury by orchestrating autophagy via HIF-1α/BNIP3 pathway, and HIF-1α inhibition could alleviate irinotecan-induced lipid accumulation in HepG2 and L-02 cells, which will provide a new clue and direction for the prevention of side effects of clinical chemotherapy drugs.

Diabetes-Induced Autophagy Dysregulation Engenders Testicular Impairment via Oxidative Stress.

Testes produce sperms, and gamete generation relies on a proper niche environment. The disruption of hierarchical regulatory homeostasis in Leydig or Sertoli cells may evoke a sterile phenotype in humans. In this study, we recapitulated type 2 diabetes mellitus by using a high-fat diet- (HFD-) fed mouse model to identify the phenotype and potential mechanism of diabetes-induced testicular impairment. At the end of the study, blood glucose levels, testosterone structure, testicular antioxidant capacity, and testosterone level and the expression of hypoxia-inducible factor- (HIF-) 1α, apoptosis-related protein cleaved-caspase3, and autophagy-related proteins such as LC3I/II, p62, and Beclin1 were evaluated. We found that long-term HFD treatment causes the development of diabetes mellitus, implicating increased serum glucose level, cell apoptosis, and testicular atrophy (P < 0.05 vs. Ctrl). Mechanistically, the results showed enhanced expression of HIF-1α in both Sertoli and Leydig cells (P < 0.05 vs. Ctrl). Advanced glycation end products (AGEs) were demonstrated to be a potential factor leading to HIF-1α upregulation in both cell types. In Sertoli cells, high glucose treatment had minor effects on Sertoli cell autophagy. However, AGE treatment stagnated the autophagy flux and escalated cell apoptosis (P < 0.05 vs. Ctrl+Ctrl). In Leydig cells, high glucose treatment was adequate to encumber autophagy induction and enhance oxidative stress. Similarly, AGE treatment facilitated HIF-1α expression and hampered testosterone production (P < 0.05 vs. Ctrl+Ctrl). Overall, these findings highlight the dual effects of diabetes on autophagy regulation in Sertoli and Leydig cells while imposing oxidative stress in both cell types. Furthermore, the upregulation of HIF-1α, which could be triggered by AGE treatment, may negatively affect both cell types. Together, these findings will help us further understand the molecular mechanism of diabetes-induced autophagy dysregulation and testicular impairment, enriching the content of male reproductive biology in diabetic patients.

Hybrid expression cassettes consisting of a milk protein promoter and a cytomegalovirus enhancer significantly increase mammary-specific expression of human lactoferrin in transgenic mice.

It is very important to develop an effective, specific, and robust expression cassette that ensures a high level of expression in the mammary glands. In this study, we designed and constructed a series of mammary gland-specific vectors containing a complex hybrid promoter/enhancer by utilizing promoter sequences from milk proteins (i.e., goat ß-casein, bovine αs1-casein, or goat ß-lactoglobulin) and cytomegalovirus enhancer sequences; vectors containing a single milk protein promoter served as controls. Chicken ß-globin insulator sequences were also included in some of these vectors. The expression of constructs was analyzed through the generation of transgenic mice. Enzyme-linked immunosorbent assay (ELISA) analysis revealed that the hybrid promoter/enhancer could drive the expression of recombinant human lactoferrin (rhLF) cDNA at high levels (1.17-8.10 mg/ml) in the milk of transgenic mice, whereas control promoters achieved a very low rhLF expression (7-40 ng/ml). Moreover, the expression of rhLF was not detected in the serum or saliva of any transgenic animal. This result shows that all constructs, driven by the hybrid promoter/enhancer, had high mammary gland-specific expression pattern. Together, our results suggest that the use of a hybrid promoter/enhancer is a valuable alternative approach for increasing mammary-specific expression of recombinant hLF in a transgenic mouse model.

Unprotected sex among HIV-positive treatment-seeking opioid-dependent adults in China: a cross-sectional study.

BACKGROUND: We set out to identify factors associated with unprotected sex among HIV-positive patients on methadone maintenance therapy (MMT) in China. METHODS: We conducted a cross-sectional study in 60 MMT clinics in Yunnan, Sichuan, Guizhou, Guangxi, and Xinjiang provinces, China, with a total of 2742 participants. RESULTS: The median age of participants was 35 years (range, 19-63 years), and 78.3% were male. More than half (1471/2742; 53.6%) were married, 6.4% (176/2742) had a regular sex partner, and 3.5% (95/2742) had 1 or more occasional sex partners. Among married participants, 64.6% (950/1471) had a spouse who was HIV negative or of unknown HIV status. Among them, 62.8% (597/950) reported sex in the past 30 days, and 31.0% (185/597) reported unprotected sex in the past 30 days. Multivariate logistic regression identified 3 factors associated with an increased risk of unprotected sex: receiving MMT in Guangxi (odds ratio [OR], 3.72 [2.05-6.75]; P < 0.001) or Xinjiang (OR, 2.23 [1.33-3.73]; P < 0.01), having a spouse that is a current or former drug user (OR, 1.80 [1.12-2.90]; P < 0.05), and having dropped out of MMT in the past 6 months (OR, 3.05 [1.63-5.71]; P < 0.001); it also identified 2 factors associated with a decreased risk of unprotected sex: being male (OR, 0.46 [0.26-0.79]; P < 0.01) and being aware of one's own HIV serostatus (OR, 0.16 [0.10-0.27]; P < 0.001). CONCLUSIONS: Many HIV-positive opioid-dependent individuals attending MMT continue to engage in high-risk sexual behaviors. Future efforts should focus on increasing awareness of HIV serostatus, retaining patients in MMT, and addressing the specific needs of female patients on MMT.

Regulatory effect of hypoxia-inducible factor-1α on hCG-stimulated endothelin-2 expression in granulosa cells from the PMSG-treated rat ovary.

Endothelin (ET)-2 plays a crucial role in ovarian ovulation in mammals. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1α-mediated transcriptional activation contributes to the increased expression of ET-2 gene in response to hCG in rat ovarian granulosa cells (GCs) during gonadotropin-induced superovulation. By real-time RT-PCR analysis, ET-2 mRNA expression was found to significantly increase in cultured ovarian GCs after treatment with hCG, or even N-carbobenzoxyl-L-leucinyl-L-leucinyl-L-norvalinal (MG-132), while this increased ET-2 mRNA expression could also be blocked by ferrous ammonium sulfate (FAS) under human chorionic gonadotropin (hCG) treatment. Further analysis also found that these changes of ET-2 mRNA were consistent with HIF-1α expression or HIF-1 activity, and HIF-1α inhibitor echinomycin inhibited ovulation in rats. Taken together, these results indicate that ET-2 is transcriptionally activated by hCG through HIF-1α-mediated mechanism in GCs. This HIF-1α-induced transcriptional activation may be one of the important mechanisms mediating the increase of ET-2 expression in GCs during the gonadotropin-induced mammalian ovulatory process in vivo.

Roles of HIF-1α/BNIP3 mediated mitophagy in mitochondrial dysfunction of letrozole-induced PCOS rats.

Mitochondrial dysfunction plays a crucial role in the pathological physiology of polycystic ovary syndrome (PCOS). Mitochondrial quality control system is vital to maintaining mitochondrial function, includes mitochondrial biosynthesis, dynamics and mitophagy. While mitophagy as a specific autophagy, plays an important role in the mitochondrial quality control system and is mediated by some signaling pathways to eliminate the excessive production of reactive oxygen species (ROS), such as hypoxia-inducible factor (HIF)-1α/B-cell lymphoma-2 adenovirus E1B 19 kDa interacting protein 3 (BNIP3). Our previous studies have found that excessive production of ROS and the decreased expression of HIF-1α in the ovaries of PCOS rats. Thus, we hypothesized that excessive ROS leads to mitochondrial dysfunction, attenuates HIF-1α/BNIP3-mediated mitophagy in the ovaries of PCOS rats, and further reduces the mitophagic defense. Firstly, the oxidative stress status was detected and found excessive ROS damages ovarian tissue in PCOS rats. Secondly, the marker proteins of mitochondrial biosynthesis/dynamics and amount were examined and found that their expression levels were abnormal, which showed that the abnormal mitochondrial quality control system leads to accumulate the excess or damaged mitochondria in PCOS ovaries. Finally, we detected the HIF-1α/BNIP3 pathway and found HIF-1α-mediated mitophagy is impaired in the ovaries of PCOS rats. Together, these results clearly demonstrated excessive ROS causes mitochondrial dysfunction via the abnormal mitochondrial quality control system, and attenuates HIF-1α/BNIP3-mediated mitophagic defense in the granulosa cells of PCOS rats, which will provide a new direction for further understanding the role of HIF-1α in the molecular mechanism of mitochondrial dysfunction in PCOS ovaries.

Effects of substrate stiffness on the viscoelasticity and migration of prostate cancer cells examined by atomic force microscopy.

The stiffness of the extracellular matrix of tumour cells plays a key role in tumour cell metastasis. However, it is unclear how mechanical properties regulate the cellular response to the environmental matrix. In this study, atomic force microscopy (AFM) and laser confocal imaging were used to qualitatively evaluate the relationship between substrate stiffness and migration of prostate cancer (PCa) cells. Cells cultured on stiff substrates (35 kPa) undergone several interesting phenomena compared to those on soft substrates (3 kPa). Here, the stimulation generated by the stiff substrates triggered the F-actin skeleton to bundle its filaments, increasing the polarity index of the external contour of PCa cells. Analysis of AFM force-distance curves indicated that the elasticity of the cells cultured on 35 kPa substrates increased while the viscosity decreased. Wound-healing experiments showed that PCa cells cultured on 35 kPa substrates have higher migration potential. These phenomena suggested that the mechanical properties may be correlated with the migration of PCa cells. After actin depolymerisation, the elasticity of the PCa cells decreased while the viscosity increased, and the migration ability was correspondingly decreased. In conclusion, this study clearly demonstrated the relationship between substrate stiffness and the mechanical properties of cells in prostate tumour metastasis, providing a basis for understanding the changes in the biomechanical properties at a single-cell level.