RANTES (C–C chemokine, regulated on activation, normal T cell expressed and secreted) is involved in progression of endometriosis, but the precise mechanism is understood inadequately. This study is to elucidate the roles of RANTES in macrophage recruitment and tolerance in the endometriotic milieu. The expression of RANTES was analyzed by immunohistochemistry. The cell co-cultures were applied to simulate the endometriotic milieu to investigate the regulation of RANTES secretion and its receptor CCR1 expression. Transwell migration assay was used for chemotaxis of U937 cells (macrophage line) to endometrial stromal cells (ESCs) and/or human pelvic mesothelial cells. The expression of CCR1 was analyzed by RT-PCR and qPCR in transcription and by western blot in translation respectively. Concentrations of RANTES, IL10, and IL12p70 were determined by ELISA. The phenotype of U937 cells and apoptosis of ESCs were analyzed by flow cytometry. We have found that the expression of RANTES is significantly higher in the endometriotic tissue and eutopic endometrium than that of the normal endometrium without endometriosis. The combination of 17β-estradiol and dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin increases significantly RANTES secretion in the endometriosis-associated cell co-culture which can recruit more macrophages, upregulate CCR1 expression, and induce tolerant phenotype, which inhibits the apoptosis of ESC in the milieu. In conclusion, the higher levels of RANTES in the ectopic milieu facilitate the onset and progression of endometriosis by macrophage recruitment and tolerance that in turn inhibits apoptosis and enhances growth of ESC.
Xiao-Qiu Wang, Jing Yu, Xue-Zhen Luo, Ying-Li Shi, Yun Wang, Ling Wang and Da-Jin Li
Ling Wang, Yu-Dong Wang, Wen-Jun Wang, Ying Zhu and Da-Jin Li
Dehydroepiandrosterone (DHEA) may be a promising agent for postmenopausal osteoporosis (PMO), but its mechanism to modulate osteoblasts (OBs) is yet to be explained. To elucidate the effects of DHEA treatment on the ovariectomized (OVX) mice and its mechanisms, we evaluated the morphology of mice bone tissue and expression of proliferating cell nuclear antigen (PCNA) in the vertebrae-derived OB after having treated the OVX animals with DHEA. The results showed that DHEA administration increased the expression of PCNA in OB and changed the bone tissue morphometry of the PMO model. To further investigate this mechanism, the OB was isolated from neonatal mice calvariae by the enzyme-digested assay, exposed to DHEA, and then analyzed for ultrastructure, DNA content, early apoptotic cells, and phosphorylation of extracellular signal-regulated kinase 1/2. It was found that DHEA promoted proliferation and inhibited apoptosis of OB significantly, via mitogen-activated protein kinase signaling pathway independent of either androgen receptor or estrogen receptor, suggesting that it may exert roles via a DHEA-specific receptor directly, not by way of conversion to androgens or estrogens.
Leping Zhao, Yong Pan, Kesong Peng, Zhe Wang, Jieli Li, Dan Li, Chao Tong, Yi Wang and Guang Liang
11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) controls the production of active glucocorticoid (GC) and has been proposed as a new target for the treatment of type 2 diabetes. We have previously reported that a natural product, curcumin, exhibited moderate inhibition and selectivity on 11β-HSD1. By analyzing the models of protein, microsome, cells and GCs-induced mice in vitro and in vivo, this study presented a novel curcumin analog, LG13, as a potent selective 11β-HSD1 inhibitor. In vivo, Type 2 diabetic mice were treated with LG13 for 42 days to assess the pharmacological benefits of 11β-HSD1 inhibitor on hepatic glucose metabolism. In vitro studies revealed that LG13 selectively inhibited 11β-HSD1 with IC50 values at nanomolar level and high selectivity over 11β-HSD2. Targeting 11β-HSD1, LG13 could inhibit prednisone-induced adverse changes in mice, but had no effects on dexamethasone-induced ones. Further, the 11β-HSD1 inhibitors also suppressed 11β-HSD1 and GR expression, indicating a possible positive feedback system in the 11β-HSD1/GR cycle. In type 2 diabetic mice induced by high fat diet plus low-dosage STZ injection, oral administration with LG13 for 6 weeks significantly decreased fasting blood glucose, hepatic glucose metabolism, structural disorders, and lipid deposits. LG13 exhibited better pharmacological effects in vivo than insulin sensitizer pioglitazone and potential 11β-HSD1 inhibitor PF-915275. These pharmacological and mechanistic insights on LG13 also provide us novel agents, leading structures, and strategy for the development of 11β-HSD1 inhibitors treating metabolic syndromes.
Wen-Li Zhao, Chun-Yan Liu, Wen Liu, Di Wang, Jin-Xing Wang and Xiao-Fan Zhao
Insect molting and metamorphosis are regulated by two hormones: 20-hydroxyecdysone (20E) and juvenile hormone (JH). The hormone 20E regulates gene transcription via the nuclear receptor EcR to promote metamorphosis, whereas JH regulates gene transcription via its intracellular receptor methoprene-tolerant (Met) to prevent larval–pupal transition. However, the function and mechanism of Met in various insect developments are not well understood. We propose that Met1 plays a key role in maintaining larval status not only by promoting JH-responsive gene transcription but also by repressing 20E-responsive gene transcription in the Lepidopteran insect Helicoverpa armigera. Met1 protein is increased during feeding stage and decreased during molting and metamorphic stages. Met1 is upregulated by JH III and a low concentration of 20E independently, but is downregulated by a high concentration of 20E. Knockdown of Met1 in larvae causes precocious pupation, decrease in JH pathway gene expression, and increase in 20E pathway gene expression. Met1 interacts with heat shock protein 90 and binds to JH response element to regulate Krüppel homolog 1 transcription in JH III induction. Met1 interacts with ultraspiracle protein 1 (USP1) to repress 20E transcription complex EcRB1/USP1 formation and binding to ecdysone response element. These data indicate that JH via Met1 regulates JH pathway gene expression and represses 20E pathway gene expression to maintain the larval status.
Xiuli Lu, Yang Li, Jianli Liu, Xiangyu Cao, Xude Wang, Delong Wang, Hisao Seo and Bing Gao
DHCR24 encodes 3β-hydroxysteroid-Δ24 reductase, catalyzing the conversion of desmosterol to cholesterol. Our previous study demonstrated that DHCR24 exerts an anti-apoptotic function as a reactive oxygen species (ROS) scavenger, for which it needs its FAD-binding domain. The membrane topology of DHCR24 on endoplasmic reticulum (ER) and the functional significance of its FAD-binding domain are not completely understood. Based on the structure predicted by bioinformatics, we studied the membrane topology of DHCR24 in murine neuroblastoma cells (N2A), using the fluorescent protease protection (FPP) technique. We showed that full-length DHCR24 is localized to the membrane of ER, whereas the predicted transmembrane (TM) domain-deleted DHCR24 mutation is localized to the cytoplasm. The change of DHCR24 localization suggests that the N-terminal TM domain is essential for the ER membrane targeting of DHCR24. The FPP assay demonstrated the membrane topology of DHCR24 with an N-terminal luminal/C-terminal cytoplasmic orientation. Measurement of intracellular ROS using H2DCFDA revealed that the ROS levels of cells infected by plasmids driving expression of full-length DHCR24 or the TM domain-deleted DHCR24 mutation after H2O2 exposure were lower than those of control cells, suggesting that the ER membrane targeting of DHCR24 is not required for its enzymatic ROS scavenging activity. Confocal fluorescence microscopy revealed that the DHCR24-overexpressed cells were protected from apoptosis in response to oxidative stress, which was accompanied by a decrease in DHCR24 content on the ER and activation of caspase-3, suggesting that the anti-apoptotic function of DHCR24 is associated with its cleavage by caspase.
Xiaohui Wang, Yidong Li, Xiaoyan Zhu, Yan Wang, Fei Diao and Jian Lu
Glucocorticoid (GC) effectively suppresses immune and inflammatory responses and inhibits the growth of several types of cells, but the role of GC and its receptor on macrophage proliferation is unclear. In our previous work, we found RAW-GR(−) cells (murine macrophage RAW264.7 cells stably transfected with GR-siRNA expression vector by RNA interference) grew faster by about twofold. In this study, we further explored the role and mechanisms of GC/GR on the proliferation of macrophage. We found that the growth of RAW264.7 cells was inhibited by dexamethasone (Dex) in a concentration-dependent manner. The mRNA and protein levels of signal regulatory protein α1 (SIRPA) were induced by GC/GR in RAW264.7 cells and SIRPA expression was decreased remarkably in RAW-GR(−) cells. Overexpression of SIRPA negatively regulated the proliferation of RAW-GR(−) cells, and inhibition of SIRPA expression by a small from RNA interference attenuated Dex-induced proliferation inhibition in RAW264.7 cells. The proliferation inhibition of GC/GR was also found in mouse peritoneal macrophage, which was associated with the increase in SIRPA induced by GC/GR as well. In addition, elevation of the expression of CDK2, cyclinD1, and cyclinB1, but not phosphorylated ERK1/2 and p38, was found in RAW-GR(−) cells. In conclusion, we provided the novel evidences that GC/GR inhibited the growth of RAW264.7 cells and mouse peritoneal macrophage, and the antiproliferative effect of GC/GR on these cells was at least in part a result from GC/GR-induced SIRPA expression. Up-regulation of CDK2, cyclinD1, and cyclinB1 was also related to the increased proliferation of RAW-GR(−) cells.
Zhipeng Li, Zhaoshui Shangguan, Yijie Liu, Jihua Wang, Xuejun Li, Shuyu Yang and Suhuan Liu
Pancreatic β-cell loss because of apoptosis is the major cause of type 1 diabetes (T1D) and late stage T2D. Puerarin possesses anti-diabetic properties; whether it acts directly on pancreatic β-cell is not clear. This study was designed to investigate the effects of puerarin on pancreatic β-cell survival and function. Diabetes was induced in male C57BL/6 mice by a single peritoneal injection of streptozotocin (STZ). Pancreatic β-cell survival and function were assessed in diabetic mice by measuring β-cell apoptosis, β-cell mass, pancreatic insulin content, and glucose tolerance, and in cultured islets and clonial MIN6 β-cells by measuring β-cell viability and apoptosis and glucose-stimulated insulin secretion. We found that pre-treatment with puerarin decreased the incidence of STZ-induced diabetes. Puerarin increased pancreatic β-cell mass via β-cell apoptosis inhibition in diabetic mice, and increased serum insulin, whereas it decreased blood glucose levels and improved glucose tolerance. In cultured islets and MIN6 cells, puerarin protected β-cell from cobalt chloride (CoCl2)-induced apoptosis and restored the impaired capacity of glucose-stimulated insulin secretion. Puerarin protection of β-cell survival involved the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. In conclusion, puerarin protects pancreatic β-cell function and survival via direct effects on β-cells, and its protection of β-cell survival is mediated by the PI3K/Akt pathway. As a safe natural plant extraction, puerarin might serve as a preventive and/or therapeutic approach for diabetes.
Yue Wang, Xiu Long Niu, Xiao Qin Guo, Jing Yang, Ling Li, Ye Qu, Cun Xiu Hu, Li Qun Mao and Dan Wang
About 40–60% of ovarian cancer (OVCA) cases express ERα, but only a small proportion of patients respond clinically to anti-estrogen treatment with estrogen receptor (ER) antagonist tamoxifen (TAM). The mechanism of TAM resistance in the course of OVCA progression remains unclear. However, IL6 plays a critical role in the development and progression of OVCA. Our recent results indicated that IL6 secreted by OVCA cells may promote the resistance of these cells to TAM via ER isoforms and steroid hormone receptor coactivator-1. Here we demonstrate that both exogenous (a relatively short period of treatment with recombinant IL6) and endogenous IL6 (generated as a result of transfection with a plasmid encoding sense IL6) increases expression of pERα-Ser118 and pERα-Ser167 in non-IL6-expressing A2780 cells, while deleting endogenous IL6 expression in IL6-overexpressing CAOV-3 cells (by transfection with a plasmid encoding antisense IL6) reduces expression of pERα-Ser118 and pERα-Ser167, indicating that IL6-induced TAM resistance may also be associated with increased expression of pERα-Ser118 and pERα-Ser167 in OVCA cells. Results of further investigation indicate that IL6 phosphorylates ERα at Ser118 and Ser167 by triggering activation of MEK/ERK and phosphotidylinositol 3 kinase/Akt signaling, respectively, to activate the ER pathway and thereby induce OVCA cells resistance to TAM. These results indicate that IL6 secreted by OVCA cells may also contribute to the refractoriness of these cells to TAM via the crosstalk between ER and IL6-mediated intracellular signal transduction cascades. Overexpression of IL6 not only plays an important role in OVCA progression but also promotes TAM resistance. Our results indicate that TAM-IL6-targeted adjunctive therapy may lead to a more effective intervention than TAM alone.
Lai Jin, Qichun Zhang, Rui Guo, Lina Wang, Juejin Wang, Rong Wan, Rongjian Zhang, Youhua Xu and Shengnan Li
Urocortin (Ucn), a corticotropin-releasing factor (CRF)-related neuropeptide binding both CRF type 1 receptor (CRFR1) and CRFR2, has recently been found in prostate cancer. However, no report has yet been known to elucidate the roles of Ucn in prostate cancer via the two receptors. In this study, the expression of both CRFR1 and CRFR2 in the mouse prostate cancer cell line RM-1 were detected and cellular apoptosis was monitored in the presence of CRF or Ucn2, the CRFR1- and CRFR2-selective agonist respectively. CRF promoted apoptosis while Ucn2 exerted the opposite effect. CRF reduced Bcl-2 expression, induced Bax expression, and hyperpolarized the mitochondrial membrane potential to activate caspase-9. On the contrary, Ucn2 increased Bcl-2 expression and decreased Bax expression, in which phosphorylation of Akt and cyclic AMP response element-binding (CREB) was involved. Pretreatment with phosphatidylinositide 3-kinase/Akt inhibitor (LY-294002) prior to Ucn2 led to downregulation of CREB phosphorylation and hence reduced Bcl-2 expression. These effects of CRF and Ucn2 were abolished by antalarmin (Anta) and antisauvagine-30, the CRFR1- and CRFR2-selective antagonist respectively. In LNCaP cell line, similar effects on cell apoptosis by CRF and Ucn2 were observed. In summary, our results demonstrated CRFR1 and CRFR2 expression in prostate cancer and indicated the opposite apoptotic roles of the two different CRFRs. These data may contribute to uncovering the pathophysiological function of endogenous Ucn in prostate tumorigenesis and progression.
Yi Lu, Wang-sheng Wang, Yi-kai Lin, Jiang-wen Lu, Wen-jiao Li, Chu-yue Zhang and Kang Sun
Our previous studies have demonstrated that human fetal membranes are capable of de novo synthesis of serum amyloid A1 (SAA1), an acute phase protein of inflammation, wherein SAA1 may participate in parturition by inducing a number of inflammation mediators including interleukine-1β, interleukine-6 and prostaglandin E2. However, the regulation of SAA1 expression in the fetal membranes remains largely unknown. In the current study, we examined the regulation of SAA1 expression by cortisol, a crucial steroid produced locally in the fetal membranes at parturition, and the interaction between cortisol and SAA1 in the feed-forward induction of SAA1 expression in human amnion fibroblasts. Results showed that cortisol-induced SAA1 expression in a concentration-dependent manner, which was greatly enhanced by SAA1 despite modest induction of SAA1 expression by itself. Mechanism studies revealed that the induction of SAA1 expression by cortisol and SAA1 was blocked by either the transcription factor STAT3 antagonist AZD0530 or siRNA-mediated knockdown of STAT3. Furthermore, cortisol- and SAA1-induced STAT3 phosphorylation in a sequential order with the induction by SAA1 preceding the induction by cortisol. However, combination of cortisol and SAA1 failed to further intensify the phosphorylation of STAT3. Consistently, cortisol and SAA1 increased the enrichment of STAT3 at the SAA1 promoter. Taking together, this study has demonstrated that cortisol and SAA1 can reinforce each other in the induction of SAA1 expression through sequential phosphorylation of STAT3. The enhancement of cortisol-induced SAA1 expression by SAA1 may lead to excessive SAA1 accumulation resulting in parturition-associated inflammation in the fetal membranes.