Activator Protein-2α Research Articles

MiR-25-3p, Positively Regulated by Transcription Factor AP-2α, Regulates the Metabolism of C2C12 Cells by Targeting Akt1.

miR-25, a member of the miR-106b-25 cluster, has been reported as playing an important role in many biological processes by numerous studies, while the role of miR-25 in metabolism and its transcriptional regulation mechanism remain unclear. In this study, gain-of-function and loss-of-function assays demonstrated that miR-25-3p positively regulated the metabolism of C2C12 cells by attenuating phosphoinositide 3-kinase (PI3K) gene expression and triglyceride (TG) content, and enhancing the content of adenosine triphosphate (ATP) and reactive oxygen species (ROS). Furthermore, the results from bioinformatics analysis, dual luciferase assay, site-directed mutagenesis, qRT-PCR, and Western blotting demonstrated that miR-25-3p directly targeted the AKT serine/threonine kinase 1 (Akt1) 3′ untranslated region (3′UTR). The core promoter of miR-25-3p was identified, and the transcription factor activator protein-2α (AP-2α) significantly increased the expression of mature miR-25-3p by binding to its core promoter in vivo, as indicated by the chromatin immunoprecipitation (ChIP) assay, and AP-2α binding also downregulated the expression of Akt1. Taken together, our findings suggest that miR-25-3p, positively regulated by the transcription factor AP-2α, enhances C2C12 cell metabolism by targeting the Akt1 gene.

AP-2α reverses vincristine-induced multidrug resistance of SGC7901 gastric cancer cells by inhibiting the Notch pathway.

Multidrug resistance (MDR) remains a major clinical obstacle in the treatment of gastric cancer (GC) since it causes tumor recurrence and metastasis. The transcription factor activator protein-2α (AP-2α) has been implicated in drug-resistance in breast cancer; however, its effects on MDR of gastric cancer are far from understood. In this study, we aimed to explore the effects of AP-2α on the MDR in gastric cancer cells selected by vincristine (VCR). Decreased AP-2α levels were markedly detected by RT-PCR and Western blot in gastric cancer cell lines (BGC-823, SGC-7901, AGS, MKN-45) compared with that in the gastric epithelial cell line (GES-1). Furthermore, we found that the expression of AP-2α in SGC7901/VCR or SGC7901/adriamycin (ADR) cells was lower than in SGC7901 cells. Thus, a vector overexpressing AP-2α was constructed and used to perform AP-2α gain-of-function studies in SGC7901/VCR cells. The decreased IC50 values of the anti-cancer drugs in sensitive and resistant cells after transfect with pcDNA3.1/AP-2α were determined in SGC7901/VCR cells by MTT assay. Moreover, flow cytometry analysis indicated that overexpressed AP-2α induced cell cycle arrest in the G0/G1 phase and promoted cell apoptosis of VCR-selected SGC7901/VCR cells. RT-PCR and Western blot demonstrated that overexpressed AP-2α can significantly induce the down-regulation of Notch1, Hes-1, P-gp and MRP1 in SGC7901/VCR cells. Similar effects can be observed when Numb (Notch inhibitor) was introduced. In addition, the intracellular ADR accumulation was markedly detected in AP-2α overexpressed or Numb cells. In conclusion, our results indicate that AP-2α can reverse the MDR of gastric cancer cells, which may be realized by inhibiting the Notch signaling pathway.

Functions of the AP-2α gene in activating apoptosis and inhibiting proliferation of gastric cancer cells both in vitro and in vivo.

IntroductionThis study was designed to investigate the potential function of the activating protein 2α (AP-2α) gene in controlling the proliferation and apoptosis of gastric cancer.Material and methodsGastric cancer cell line MCG-803 cells and normal cell line GES-1 cells were selected to transfect pcDNA3.1(+)-AP-2α and pcDNA3.1(+) plasmids, respectively. Both mRNA and protein levels of AP-2α in each group transfected with the pcDNA3.1(+)-AP-2α plasmids were up-regulated after 48 h by real-time PCR and Western blotting analysis, leading to marked proliferation inhibition and significant cell cycle arrest.ResultspcDNA3.1(+)-AP-2α reduced tumor tissue growth in a subcutaneous tumor gastric carcinoma nude mouse model. Protein over-expression of AP-2α in the nude mouse model was accompanied by down-regulation of Blc-2 and ErbB2, resulting in the up-regulation of caspase-3, -8, and -9, ERα and p21WAF1/CIP1.ConclusionsThe reintroduction of the AP-2α gene by pcDNA3.1 could inhibit gastric tumor growth in vitro and in vivo, which may be an alternative future therapeutic molecular target for human gastric cancer.

Epigenetic programming of Dnmt3a mediated by AP2α is required for granting preadipocyte the ability to differentiate.

Adipogenesis has an important role in regulating energy homeostasis in mammals. 3T3-L1 preadipocytes have been widely used as an in vitro model for analyzing the molecular mechanism of adipogenesis. Previous reports indicated that the stage of contact inhibition (CI), through which the proliferating cells exit from the cell cycle, was required for granting preadipocyte the ability to differentiate. While this kind of the granting mechanism remains elusive. In the present study, we showed that DNA (cytosine-5) methyltransferase 3a (Dnmt3a) was upregulated at both the mRNA and protein level during the CI stage, and resulted in increasing promoter methylation of adipogenic genes. We further identified that the expression of Activator protein 2α (AP2α), a member of the transcription factor activator protein 2 (AP2) family, was highly correlated with the expression of Dnmt3a during the CI stage. In addition, we showed that AP2α transcriptionally upregulated Dnmt3a by directly binding to its proximal promoter region. Importantly, treatment of 3T3-L1 preadipocytes with AP2α-specific siRNAs inhibited the preadipocyte differentiation in a stage-dependent manner, supporting the conclusion that AP2α has an important role during the CI stage. Furthermore, overexpression of Dnmt3a partially rescued the impairment of adipogenesis induced by AP2α knockdown. Collectively, our findings reveal that AP2α is an essential regulator for granting preadipocyte the ability to differentiate through the upregulation of Dnmt3a expression during the CI stage.

Activation of activator protein 2 alpha by aspirin alleviates atherosclerotic plaque growth and instabilityin vivo

AimsAspirin has been used for the secondary prevention and treatment of cardiovascular disease for several decades. We investigated the roles of transcriptional factor activator protein 2α (AP-2α) in the beneficial effects of aspirin in the growth and vulnerability of atherosclerotic plaque.Methods and ResultsIn mice deficient of apolipoprotein E (Apoe-/-), aspirin (20, 50 mg/kg/day) suppressed the progression of atherosclerosis in aortic roots and increased the plaque stability in carotid atherosclerotic plaques induced by collar-placement. In vivo lentivirus-mediated RNA interference of AP-2α reversed the inhibitory effects of aspirin on atherosclerosis in Apoe-/- mice. Mechanically, aspirin increased AP-2α phosphorylation and its activity, upregulated IkBα mRNA and protein levels, and reduced oxidative stress in cultured vascular smooth muscle cells. Furthermore, deficiency of AP-2α completely abolished aspirin-induced upregulation of IkBα levels and inhibition of oxidative stress in Apoe-/- mice. Clinically, conventional doses of aspirin increased AP-2α phosphorylation and IkBα protein expression in humans subjects.ConclusionAspirin activates AP-2α to upregulate IkBα gene expression, resulting in attenuations of plaque development and instability in atherosclerosis.

Down-regulation of EPHX2 gene transcription by Sp1 under high-glucose conditions.

sEH (soluble epoxide hydrolase), which is encoded by the EPHX2 gene, regulates the actions of bioactive lipids, EETs (epoxyeicosatrienoic acids). Previously, we found that high-glucose-induced oxidative stress suppressed sEH levels in a hepatocarcinoma cell line (Hep3B) and sEH was decreased in streptozotocin-induced diabetic mice invivo. In the present study, we investigated the regulatory mechanisms underlying EPHX2 transcriptional suppression under high-glucose conditions. The decrease in sEH was prevented by an Sp1 (specificity protein 1) inhibitor, mithramycin A, and overexpression or knockdown of Sp1 revealed that Sp1 suppressively regulated sEH expression, in contrast with the general role of Sp1 on transcriptional activation. In addition, we found that AP2α (activating protein 2α) promoted EPHX2 transcription. The nuclear transport of Sp1, but not that of AP2α, was increased under high glucose concomitantly with the decrease in sEH. Within the EPHX2 promoter -56/+32, five Sp1-binding sites were identified, and the mutation of each of these sites showed that the first one (SP1_1) was important in both suppression by Sp1 and activation by AP2α. Furthermore, overexpression of Sp1 diminished the binding of AP2α by DNA-affinity precipitation assay and ChIP, suggesting competition between Sp1 and AP2α on the EPHX2 promoter. These findings provide novel insights into the role of Sp1in transcriptional suppression, which may be applicable to the transcriptional regulation of other genes.

Long non-coding RNA CCAL regulates colorectal cancer progression by activating Wnt/β-catenin signalling pathway via suppression of activator protein 2α

ObjectiveLong non-coding RNAs (lncRNAs) are emerging as key molecules in cancers, yet their potential molecular mechanisms are not well understood. The objective of this study is to examine the expression...

ETS1 induces human trophoblast differentiation.

A possible role for the transcription factor v-ets avian erythroblastosis virus E26 oncogene homolog 1 (ETS1) in human trophoblast cell differentiation was examined using a highly enriched fraction of human mononuclear cytotrophoblast cells (CTBs) that differentiate spontaneously in vitro to a multinucleated syncytiotrophoblast cell (STB) phenotype. ETS1 mRNA and protein levels were abundant in freshly isolated CTBs and decreased as the cells differentiated. Silencing of ETS1 expression in freshly prepared CTBs markedly attenuated syncytialization, as demonstrated by desmoplakin staining, and blocked the induction of syncytin, the transcription factor activator protein-2α, placental lactogen, and other STB-specific genes. Conversely, overexpression of ETS1 in primary trophoblast cells induced STB marker gene mRNAs and transactivated each of the gene proximal promoters. Taken together, these findings strongly suggest a critical role for ETS1 in the induction of human villus CTB differentiation. The effect of ETS1 on syncytialization likely results, at least in part, from inhibition of syncytin expression, whereas the induction of STB marker genes likely results in part from transactivation by activator protein-2α.

Suv39h1 mediates AP-2α-dependent inhibition of C/EBPα expression during adipogenesis.

Previous studies have shown that CCAAT/enhancer-binding protein α (C/EBPα) plays a very important role during adipocyte terminal differentiation and that AP-2α (activator protein 2α) acts as a repressor to delay the expression of C/EBPα. However, the mechanisms by which AP-2α prevents the expression of C/EBPα are not fully understood. Here, we present evidence that Suv39h1, a histone H3 lysine 9 (H3K9)-specific trimethyltransferase, and G9a, a euchromatic methyltransferase, both interact with AP-2α and enhance AP-2α-mediated transcriptional repression of C/EBPα. Interestingly, we discovered that G9a mediates dimethylation of H3K9, thus providing the substrate, which is methylated by Suv39h1, to H3K9me3 on the C/EBPα promoter. The expression level of AP-2α was consistent with enrichment of H3K9me2 and H3K9me3 on the C/EBPα promoter in 3T3-L1 preadipocytes. Knockdown of Suv39h markedly increased C/EBPα expression and promoted adipogenesis. Conversely, ectopic expression of Suv39h1 delayed C/EBPα expression and impaired the accumulation of triglyceride, while simultaneous knockdown of AP-2α or G9a partially rescued this process. These findings indicate that Suv39h1 enhances AP-2α-mediated transcriptional repression of C/EBPα in an epigenetic manner and further inhibits adipocyte differentiation.

Prepubertal exposure to elevated manganese results in estradiol regulated mammary gland ductal differentiation and hyperplasia in female rats.

Evidence suggests that environmental substances regulating estrogenic pathways during puberty may be detrimental to the developing mammary gland (MG). Manganese (Mn) is a trace mineral required for normal physiological processes. Prepubertal exposure to Mn induces precocious puberty in rats, an event associated with early elevations in puberty-related hormones, including estradiol (E2). However, until now the effect of Mn-induced precocious MG development has not been determined. Therefore, we assessed the ability of prepubertal Mn exposure to advance normal MG development and alter E2 driven pathways involved in tumorigenesis. Sprague Dawley female rats were gavaged daily with either 10 mg/kg manganese chloride (MnCl2) or saline (control) from postnatal day (PND) 12 through PND 30. Blood and MGs were collected on PNDs 30 and 120. Compared to controls, serum E2 levels on PND 30 were elevated (p < 0.05) in the Mn-treated group. Mn exposure significantly increased differentiated MG terminal ductal structures and the percentage of MG epithelial cells that stained positive for the proliferative marker, Ki67, at PND 30 (p < 0.001) and PND 120 (p < 0.001). Levels of Mn (ppm) were not elevated in these MGs. Mn-treated animals (40%) exhibited reactive stroma and intra-luminal focal hyperplasia in hemotoxylin and eosin stained MGs at PND 120. Furthermore, Mn exposure resulted in elevated protein expression levels of estrogen receptor α, activator protein 2α, phosphorylated (p)-Akt, and p53 in MGs on PND 120, but not on PND 30. Collectively, these data show that exposure to a supplemental dose of Mn causes accelerated pubertal MG growth which can progress to adult hyperplasia; thus, providing evidence that early life Mn exposure may increase susceptibility to breast cancer.

RNF20 promotes the polyubiquitination and proteasome-dependent degradation of AP-2&amp;alpha; protein

Transcription factor activator protein 2α (AP-2α) is a negative regulator of adipogenesis by repressing the transcription of CCAAT/enhancer binding protein (C/EBPα) gene. During adipogenesis, AP-2α is degraded, leading to transcriptional up-regulation of C/EBPα. However, the mechanism for AP-2α degradation is not clear. Here, using immunoprecipitation assay and mass spectrometry, we identified ring finger protein 20 (RNF20) as an AP-2α-interacting protein in 3T3-L1 preadipocytes. RNF20 has been proved to be an E3 ubiquitin ligase for both histone H2B and tumor suppressor ErbB3-binding protein 1 (Ebp1). In this study, we demonstrated that RNF20 co-localized and interacted with AP-2α, and promoted its polyubiquitination and proteasome-dependent degradation. Over-expression of RNF20 inhibited the activity of AP-2α and rescued the C/EBPα expression which was inhibited by AP-2α. These results suggested that RNF20 may play roles in adipocyte differentiation by stimulating ubiquitin-proteasome-dependent degradation of AP-2α.

AP2α transcriptional activity is essential for retinoid-induced neuronal differentiation of mesenchymal stem cells

Pre-activation of the retinoid signaling pathway by all-trans retinoic acid facilitates neuronal differentiation of mesenchymal stem cells. Using protein/DNA based screening assays, we identified activator protein 2α as an important downstream target of all-trans retinoic acid. Although all-trans retinoic acid treatment significantly increased activator protein 2α transcriptional activity, it did not affect its expression. Inhibition of activator protein 2α with dominant-negative mutants reduced ATRA-induced differentiation of mesenchymal stem cells into neurons and reversed its associated functional recovery of memory impairment in the cell-based treatment of a hypoxic-ischemic brain damage rat model. Dominant-negative mutants of activator protein 2α inhibited the expression of neuronal markers which were induced by retinoic acid receptor β activation. All-trans retinoic acid treatment increased phosphorylation of activator protein 2α and resulted in its nuclear translocation. This was blocked by siRNA-mediated knockdown of retinoic acid receptor β. Furthermore, we found that retinoic acid receptor β directly interacted with activator protein 2α. In summary, the regulation of all-trans retinoic acid on activator protein 2α transcriptional activity was mediated by activation of retinoic acid receptor β and subsequent phosphorylation and nuclear translocation of activator protein 2α. Our results strongly suggest that activator protein 2α transcriptional activity is essential for all-trans retinoic acid-induced neuronal differentiation of mesenchymal stem cells.

CAPN 7 promotes the migration and invasion of human endometrial stromal cell by regulating matrix metalloproteinase 2 activity

BackgroundMatrix metalloproteinase 2 (MMP-2) has been reported to be an important regulator of cell migration and invasion through degradation of the extracellular matrix (ECM) in many diseases, such as cancer and endometriosis. Here, we found calcium-activated neutral protease 7 (CAPN 7) expression was markedly upregulated in the eutopic endometrium and endometrial stromal cells of women diagnosed with endometriosis. Our studies were carried out to detect the effects of CAPN 7 on human endometrial stromal cell (hESC) migration and invasion.MethodsWestern blotting and quantitative real-time PCR were used to detect the expression of CAPN 7 in endometriosis patients and normal fertile women. Scratch-wound-healing and invasion chamber assay were used to investigate the role of CAPN 7 in hESC migration and invasion. Western blotting, quantitative real-time PCR and zymography were carried out to detect the effect of CAPN 7 on the expressions and activity of MMP-2.ResultsCAPN 7 was markedly up-regulated in endometriosis, thereby promoting the migration and invasion of hESC. CAPN 7 overexpression led to increased expression of MMP-2 and tissue inhibitor of metalloproteinases 2 (TIMP-2); CAPN 7 knockdown reversed these changes. CAPN 7 increased MMP-2 activity by increasing the ratio of MMP-2 to TIMP-2. We also found that OA-Hy (an MMP-2 inhibitor) decreased the effects of CAPN 7 overexpression on hESC migration and invasion by approximately 50% and 55%, respectively. Additionally, a coimmunoprecipitation assay demonstrated that CAPN 7 interacted with activator protein 2α (AP-2α): an important transcription factor of MMP-2.ConclusionsCAPN 7 promotes hESC migration and invasion by increasing the activity of MMP-2 via an increased ratio of MMP-2 to TIMP-2.

AP-2α suppresses invasion in BeWo cells by repression of matrix metalloproteinase-2 and -9 and up-regulation of E-cadherin

Preeclampsia complicates 5-10% of pregnancies and is a leading cause of maternal/fetal morbidity and mortality. Although the cause is unknown, the reduced migration/invasion of extravillous trophoblasts is generally regarded as a key feature of preeclampsia genesis. The present study examined the expression of activator protein-2α (AP-2α), tissue inhibitor of metalloproteinase 2 (TIMP-2), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and E-cadherin in severe preeclamptic placentas and normal placentas using real-time PCR and immunohistochemistry. The expression levels of AP-2α, TIMP-2, and E-cadherin were elevated, while MMP-2 and MMP-9 levels were decreased in severe preeclamptic placentas when compared with normal placentas. To explore the underlying molecular mechanisms, BeWo cells were transfected with an AP-2α-expression construct as well as a siRNA against AP-2α. The over-expression of AP-2α decreased the invasive abilities of BeWo cells. AP-2α induction was followed by the induction of TIMP-2 and E-cadherin and a significant reduction of MMP-2 and MMP-9. Whereas in AP-2α-silencing BeWo cells, we observed the decreased expression of TIMP-2 and E-cadherin and the increased expression of MMP-2 and MMP-9. We presume that AP-2α may suppress trophoblast invasion by repression of MMP-2 and MMP-9 and up-regulation of E-cadherin, thus leading to shallow placentation in severe preeclampsia.

Activator Protein-2α Mediates Carbon Monoxide–Induced Stromal Cell–Derived Factor-1α Expression and Vascularization in Ischemic Heart

Increased cardiac stromal cell-derived factor-1α (SDF-1α) expression promotes neovascularization and myocardial repair after ischemic injury through recruiting stem cells and reducing cardiomyocyte death. Previous studies have shown that heme oxygenase-1 and its reaction byproduct, carbon monoxide (CO), induce SDF-1α expression in ischemic heart. However, the mechanism underlying heme oxygenase-1/CO-induced cardiac SDF-1α expression remains elusive. This study aims to investigate the signaling pathway and the transcriptional factor that mediate CO-induced SDF-1α gene expression and cardioprotection. CO gas and a CO-releasing compound, tricarbonyldichlororuthenium (II) dimer, dose-dependently induced SDF-1α expression in primary neonatal cardiomyocytes and H9C2 cardiomyoblasts. Promoter luciferase-reporter assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation demonstrated that the activator protein 2α (AP-2α) mediated tricarbonyldichlororuthenium (II) dimer-induced SDF-1α gene transcription. Tricarbonyldichlororuthenium (II) dimer induced AP-2α expression via protein kinase B (AKT)-dependent signaling. AKT inhibition or AP-2α knockdown reduced tricarbonyldichlororuthenium (II) dimer-induced SDF-1α expression. Coronary ligation induced transient increases of cardiac AP-2α and SDF-1α expression, which were declined at 1 week postinfarction in mice. Periodic exposure of coronary-ligated mice to CO (250 ppm for 1 hour/day, 6 days) resumed the induction of AP-2α and SDF-1α gene expression in infarcted hearts. Immunohistochemistry and echocardiography performed at 4 weeks after coronary ligation revealed that CO treatment enhanced neovascularization in the myocardium of peri-infarct region and improved cardiac function. CO-mediated SDF-1α expression and cardioprotection was ablated by intramyocardial injection of lentivirus bearing specific short hairpin RNA targeting AP-2α. Our data demonstrate that AKT-dependent upregulation of AP-2α is essential for CO-induced SDF-1α expression and myocardial repair after ischemic injury.

A fluorescence-based demonstration of intestinal villi and epithelial cell in chickens fed dietary silicic acid powder including bamboo vinegar compound liquid.

This study investigates the combined effect of silicic acid and bamboo vinegar compound liquid (SPV) on the growth and intestinal histological alterations in poultry. Forty-eight 7-day-old male Sanuki Cochin chickens were fed a commercial mash diet supplemented with SPV at 0, 0.1, 0.2, and 0.3% level ad libitum for 112 days. Body weight gain tended to improve with increased concentrations of dietary SPV, although these results were not statistically significant (P<0.1). Tissue observation by light microscopy revealed that the jejunal villus height (P<0.01) and duodenal and jejunal villus area (P<0.05) increased in the 0.2 and 0.3% SPV groups, respectively, compared with the control. Cell mitosis within the duodenum and jejunum also increased in the 0.2 and 0.3% SPV groups. Scanning electron microscopy revealed a prominent increase in the number of protuberant cells on the villus apical surface of the duodenum and jejunum for the 0.2 and 0.3% SPV groups compared with the control. Poultry in the 0.3% SPV group had the highest body weight gain and hypertrophied histological alterations of intestinal villi. Fluorescent microscopic images of cell mitosis and protuberant cells in the duodenal crypt clearly confirmed positive reactions for the activator protein 2α (AP-2α) and proliferating cell nuclear antigen (PCNA), compared with the control. The present results indicate that dietary SPV stimulates adsorption by the epithelial cells, which activate cell proliferation and self-renewal and regulate the expression of cell cycle regulators AP-2α and PCNA, resulting in higher body weight gain. Thus, we can conclude that a concentration of 0.3% dietary SPV is ideal for promoting growth in poultry.

Expression of AP-2α, AP-2γ and ESDN in primary melanomas: Correlation with histopathological features and potential prognostic value

Melanoma is characterized by increasing trends of incidence and high metastatic potential [1]. The transition from non-invasive to invasive and metastatic stage is characterized by a multi-step process by which tumour cells acquire the ability to detach and invade adjacent tissues. Loss of the transcription factor activator protein-2α (AP-2α) is an important molecular event in melanoma progression resulting in deregulation of AP-2 target genes involved in tumour growth and metastasis and associated with short Disease-Free-Survival (DFS) [2,3].

Abnormal expression of transcription factor activator protein-2α in pathologic placentas

Recent studies from our laboratory have indicated that the transcription factor activator protein-2α plays a critical role in the differentiation of human villous cytotrophoblast cells to syncytiotrophoblast cells. However, little is known about the expression of activator protein-2α in placentas from pathologic pregnancies. This study compares the expression of activator protein-2α in placentas from high-risk pregnancies to gestational age-matched controls. Paracentral sections from grossly unremarkable areas of 10 placentas from each group of pregnancies complicated by mild preeclampsia, severe preeclampsia, diabetes mellitus, chronic hypertension, and fetal growth restriction and 10 control cases of placentas from normal pregnancies matched for gestational age were double immunostained for activator protein-2α and E-cadherin. The total numbers of cytotrophoblast cells and syncytiotrophoblast nuclei and the numbers of activator protein-2α-positive and activator protein-2α-negative nuclei in both of these cell types were counted by 2 pathologists blinded to disease status, in 10 representative×40 high-power fields for each placenta. Abnormal placental maturation in most of pathologic pregnancies was evidenced by a 1.5- to 1.7-fold lower expression ratio of syncytiotrophoblast cell to cytotrophoblast cell. Activator protein-2α in syncytiotrophoblast cells was lower in mild preeclampsia, diabetes mellitus, hypertension, and fetal growth restriction (P<.0001 in each instance) and was higher by 2-fold in severe preeclampsia, although this increase was not statistically significant (P=.3). Because activator protein-2α has been shown to be critical for villous cytotrophoblast cell differentiation, our findings suggest that abnormalities in the activator protein-2α cascade of transcription factors and/or signaling molecules may contribute to the pathogenesis of the abnormal maturation in placentas in certain types of high-risk pregnancies. The different pattern of activator protein-2α expression in mild and severe preeclampsia clearly suggests that these conditions may have 2 independent pathogenic mechanisms.

Activation of AMP-activated protein kinase α2 by nicotine instigates formation of abdominal aortic aneurysms in mice in vivo

Smoking is the only modifiable risk factor that is associated with the development, expansion and rupture of abdominal aortic aneurysm (AAA). However, the causative link between cigarette smoke and AAA is unknown. Here we report a causative link between smoking and AAA in vivo. Acute infusion of angiotensin II (AngII) or nicotine, a major component of cigarette smoke, markedly increased the incidence of AAA in apolipoprotein E (apoE) knockout (Apoe(-/-)) mice and in mice deficient in both apoE and the AMP-activated kinase α1 subunit (AMPK-α1) (Apoe(-/-); Prkaa1(-/-) mice). In contrast, genetic deletion of AMPK-α2 (Apoe(-/-); Prkaa2(-/-) mice) ablated nicotine- or AngII-triggered AAA in vivo. Mechanistically, we found that both nicotine and AngII activated AMPK-α2 in cultured vascular smooth muscle cells (VSMCs), resulting in the phosphorylation of activator protein 2α (AP-2α) and consequent matrix metallopeptidase 2 (MMP2) gene expression. We conclude that smoking (through nicotine) instigates AAA through AMPK-α2–mediated AP-2α–dependent MMP2 expression in VSMCs.

Delivery of AP-2α siRNA into cultured bovine trophoblast cells by electroporation repressed key placenta-specific gene expression

Binucleate trophoblast giant cells (BNC) characteristically appear early in gestation in the bovine placenta. They secret pivotal hormones and cytokines for feto-maternal communication, for example, expression of placental lactogens (CSH1), prolactin-related protein 1 (PRP1) and pregnancy-associated glycoprotein 1 (PAG1) are necessary for pregnancy establishment in bovine. These genes transcription are regulated in a temporal and spatial manner, however, molecular mechanisms by which these gene transcriptions are regulated in this manner have not been firmly elucidated. In this study, a cell culture model for bovine trophoblast cells was initially established, small interfering RNA duplexes against Activator Protein-2α (TFAP2A) was transfected into the cells by electroporation, and transcripts of CSH1, PRP1 and PAG1 were measured by qPCR. The results showed that trophoblast giant cells were confluent for 90% after cultured for 10days, and BNC constituted of a population of more than 45% of the total cells. Using a fluorescein-labeled non-silencing siRNA duplex, an electroporation protocol yielding routinely >93% positive cells could be established, and siRNA duplex transfection demonstrated an efficient knockdown of cellular AP-2α mRNA level by 72.30±3.28% in electroporated cells. Finally, CSH1, PRP1 and PAG1 genes expression were effectively down-regulated by 65.45±6.38% (P<0.01), 40.73±11.72% (P<0.01) and 11.59±1.88% (P<0.05), respectively. It was therefore suggested that electroporating siRNA into bovine trophoblast cells could be an efficient method to manipulate BNC function and to study the regulation mechanism of specific gene transcription without the use of chemical transfection reagents. It was suggested that AP-2α could be at least involved in the regulation of expression CSH1 and PRP1 transcripts.