SATB1 Chromatin Loops Regulate Megakaryocyte/Erythroid Progenitor Expansion by Facilitating HSP70 and GATA1 Induction

Diamond Blackfan anemia (DBA) is an inherited bone marrow failure syndrome associated with severe anemia, congenital malformations, and an increased risk of developing cancer. The chromatin-binding special AT-rich sequence-binding protein-1 (SATB1) is downregulated in megakaryocyte/erythroid progenitors (MEPs) in patients and cell models of DBA, leading to a reduction in MEP expansion. Here we demonstrate that SATB1 expression is required for the upregulation of the critical erythroid factors heat shock protein 70 (HSP70) and GATA1 which accompanies MEP differentiation. SATB1 binding to specific sites surrounding the HSP70 genes promotes chromatin loops that are required for the induction of HSP70, which, in turn, promotes GATA1 induction. This demonstrates that SATB1, although gradually downregulated during myelopoiesis, maintains a biological function in early myeloid progenitors.

Cryo-EM, Protein Engineering, and Simulation Enable the Development of Peptide Therapeutics against Acute Myeloid Leukemia

Cryogenic electron microscopy (cryo-EM) has emerged as a viable structural tool for molecular therapeutics development against human diseases. However, it remains a challenge to determine structures of proteins that are flexible and smaller than 30 kDa. The 11 kDa KIX domain of CREB-binding protein (CBP), a potential therapeutic target for acute myeloid leukemia and other cancers, is a protein which has defied structure-based inhibitor design. Here, we develop an experimental approach to overcome the size limitation by engineering a protein double-shell to sandwich the KIX domain between apoferritin as the inner shell and maltose-binding protein as the outer shell. To assist homogeneous orientations of the target, disulfide bonds are introduced at the target-apoferritin interface, resulting in a cryo-EM structure at 2.6 Å resolution. We used molecular dynamics simulations to design peptides that block the interaction of the KIX domain of CBP with the intrinsically disordered pKID domain of CREB. The double-shell design allows for fluorescence polarization assays confirming the binding between the KIX domain in the double-shell and these interacting peptides. Further cryo-EM analysis reveals a helix-helix interaction between a single KIX helix and the best peptide, providing a possible strategy for developments of next-generation inhibitors.

Comparison of the Transcriptomic Signatures in Pediatric and Adult CML

Simple Summary

To investigate whether pediatric and adult chronic myeloid leukemia (CML) have unique molecular characteristics, we studied the transcriptomic signature of pediatric and adult CML cells using high-throughput RNA sequencing. We identified differentially expressed genes and pathways unique to pediatric CML cells compared to adult CML cells. The Rho pathway was significantly dysregulated in pediatric CML cells compared to adult CML cells, suggesting the potential importance in the pathogenesis of pediatric CML. Our study is the first to compare transcriptome profiles of CML across different age groups. A better understanding of the biology of CML across different ages may inform future treatment approaches.

Abstract

Children with chronic myeloid leukemia (CML) tend to present with higher white blood counts and larger spleens than adults with CML, suggesting that the biology of pediatric and adult CML may differ. To investigate whether pediatric and adult CML have unique molecular characteristics, we studied the transcriptomic signature of pediatric and adult CML CD34+ cells and healthy pediatric and adult CD34+ control cells. Using high-throughput RNA sequencing, we found 567 genes (207 up- and 360 downregulated) differentially expressed in pediatric CML CD34+ cells compared to pediatric healthy CD34+ cells. Directly comparing pediatric and adult CML CD34+ cells, 398 genes (258 up- and 140 downregulated), including many in the Rho pathway, were differentially expressed in pediatric CML CD34+ cells. Using RT-qPCR to verify differentially expressed genes, VAV2 and ARHGAP27 were significantly upregulated in adult CML CD34+ cells compared to pediatric CML CD34+ cells. NCF1, CYBB, and S100A8 were upregulated in adult CML CD34+ cells but not in pediatric CML CD34+ cells, compared to healthy controls. In contrast, DLC1 was significantly upregulated in pediatric CML CD34+ cells but not in adult CML CD34+ cells, compared to healthy controls. These results demonstrate unique molecular characteristics of pediatric CML, such as dysregulation of the Rho pathway, which may contribute to clinical differences between pediatric and adult patients.

RSK inhibitor BI-D1870 inhibits acute myeloid leukemia cell proliferation by targeting mitotic exit

The 90 kDa Ribosomal S6 Kinase (RSK) drives cell proliferation and survival in cancers, although its oncogenic mechanism has not been well characterized. Phosphorylated level of RSK (T573) was increased in acute myeloid leukemia (AML) patients and associated with poor survival. To examine the role of RSK in AML, we analyzed apoptosis and the cell cycle profile following treatment with BI-D1870, a potent inhibitor of RSK. BI-D1870 treatment increased the G2/M population and induced apoptosis in AML cell lines and patient AML cells. Characterization of mitotic phases showed that the metaphase/anaphase transition was significantly inhibited by BI-D1870. BI-D1870 treatment impeded the association of activator CDC20 with APC/C, but increased binding of inhibitor MAD2 to CDC20, preventing mitotic exit. Moreover, the inactivation of spindle assembly checkpoint or MAD2 knockdown released cells from BI-D1870-induced metaphase arrest. Therefore, we investigated whether BI-D1870 potentiates the anti-leukemic activity of vincristine by targeting mitotic exit. Combination treatment of BI-D1870 and vincristine synergistically increased mitotic arrest and apoptosis in acute leukemia cells. These data show that BI-D1870 induces apoptosis of AML cells alone and in combination with vincristine through blocking mitotic exit, providing a novel approach to overcoming vincristine resistance in AML cells.

Repurposing Drugs for Acute Myeloid Leukemia: A Worthy Cause or a Futile Pursuit?

Acute myeloid leukemia (AML) is a clinically and genetically heterogenous malignancy of myeloid progenitor cells that affects patients of all ages. Despite decades of research and improvement in overall outcomes, standard therapy remains ineffective for certain subtypes of AML. Current treatment is intensive and leads to a number of secondary effects with varying results by patient population. Due to the high cost of discovery and an unmet need for new targeted therapies that are well tolerated, alternative drug development strategies have become increasingly attractive. Repurposing existing drugs is one approach to identify new therapies with fewer financial and regulatory hurdles. In this review, we provide an overview of previously U.S. Food and Drug Administration (FDA) approved non-chemotherapy drugs under investigation for the treatment of AML.

MMP9 inhibition increases erythropoiesis in RPS14-deficient del(5q) MDS models through suppression of TGF-β pathways

The del(5q) myelodysplastic syndrome (MDS) is a distinct subtype of MDS, associated with deletion of the ribosomal protein S14 (RPS14) gene that results in macrocytic anemia. This study sought to identify novel targets for the treatment of patients with del(5q) MDS by performing an in vivo drug screen using an rps14-deficient zebrafish model. From this, we identified the secreted gelatinase matrix metalloproteinase 9 (MMP9). MMP9 inhibitors significantly improved the erythroid defect in rps14-deficient zebrafish. Similarly, treatment with MMP9 inhibitors increased the number of colony forming unit-erythroid colonies and the CD71+ erythroid population from RPS14 knockdown human BMCD34+ cells. Importantly, we found that MMP9 expression is upregulated in RPS14-deficient cells by monocyte chemoattractant protein 1. Double knockdown of MMP9 and RPS14 increased the CD71+ population compared with RPS14 single knockdown, suggesting that increased expression of MMP9 contributes to the erythroid defect observed in RPS14-deficient cells. In addition, transforming growth factor β (TGF-β) signaling is activated in RPS14 knockdown cells, and treatment with SB431542, a TGF-β inhibitor, improved the defective erythroid development of RPS14-deficient models. We found that recombinant MMP9 treatment decreases the CD71+ population through increased SMAD2/3 phosphorylation, suggesting that MMP9 directly activates TGF-β signaling in RPS14-deficient cells. Finally, we confirmed that MMP9 inhibitors reduce SMAD2/3 phosphorylation in RPS14-deficient cells to rescue the erythroid defect. In summary, these study results support a novel role for MMP9 in the pathogenesis of del(5q) MDS and the potential for the clinical use of MMP9 inhibitors in the treatment of patients with del(5q) MDS.

SAR optimization studies on modified salicylamides as a potential treatment for acute myeloid leukemia through inhibition of the CREB pathway

Disruption of cyclic adenosine monophosphate response element binding protein (CREB) provides a potential new strategy to address acute leukemia, a disease associated with poor prognosis, and for which conventional treatment options often carry a significant risk of morbidity and mortality. We describe the structure-activity relationships (SAR) for a series of XX-650-23 derived from naphthol AS-E phosphate that disrupts binding and activation of CREB by the CREB-binding protein (CBP). Through the development of this series, we identified several salicylamides that are potent inhibitors of acute leukemia cell viability through inhibition of CREB-CBP interaction. Among them, a biphenyl salicylamide, compound 71, was identified as a potent inhibitor of CREB-CBP interaction with improved physicochemical properties relative to previously described derivatives of naphthol AS-E phosphate.

CBP Modulates Sensitivity to Dasatinib in Pre-BCR+ Acute Lymphoblastic Leukemia

Dasatinib is a multi-tyrosine kinase inhibitor approved for treatment of Ph⁺ acute lymphoblastic leukemia (ALL), but its efficacy is limited by resistance. Recent preclinical studies suggest that dasatinib may be a candidate therapy in additional ALL subtypes including pre-BCR⁺ ALL. Here we utilized shRNA library screening and global transcriptomic analysis to identify several novel genes and pathways that may enhance dasatinib efficacy or mitigate potential resistance in human pre-BCR⁺ ALL. Depletion of the transcriptional coactivator CBP increased dasatinib sensitivity by downregulating transcription of the pre-BCR signaling pathway previously associated with dasatinib sensitivity. Acquired resistance was due, in part, to upregulation of alternative pathways including WNT through a mechanism, suggesting transcriptional plasticity. Small molecules that disrupt CBP interactions with the CREB KID domain or β-catenin showed promising preclinical efficacy in combination with dasatinib. These findings highlight novel modulators of sensitivity to targeted therapies in human pre-BCR⁺ ALL, which can be reversed by small-molecule inhibitors. They also identify promising therapeutic approaches to ameliorate dasatinib sensitivity and prevent resistance in ALL.Significance: These findings reveal mechanisms that modulate sensitivity to dasatinib and suggest therapeutic strategies to improve the outcome of patients with acute lymphoblastic leukemia.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/22/6497/F1.large.jpg Cancer Res; 78(22); 6497-508. ©2018 AACR.

Niclosamide suppresses acute myeloid leukemia cell proliferation through inhibition of CREB-dependent signaling pathways

CREB (cAMP Response Element Binding protein) is a transcription factor that is overexpressed in primary acute myeloid leukemia (AML) cells and associated with a decreased event-free survival and increased risk of relapse. We recently reported a small molecule inhibitor of CREB, XX-650-23, which inhibits CREB activity in AML cells. Structure-activity relationship analysis for chemical compounds with structures similar to XX-650-23 led to the identification of the anthelminthic drug niclosamide as a potent anti-leukemic agent that suppresses cell viability of AML cell lines and primary AML cells without a significant decrease in colony forming activity of normal bone marrow cells. Niclosamide significantly inhibited CREB function and CREB-mediated gene expression in cells, leading to apoptosis and G1/S cell cycle arrest with reduced phosphorylated CREB levels. CREB knockdown protected cells from niclosamide treatment-mediated cytotoxic effects. Furthermore, treatment with a combination of niclosamide and CREB inhibitor XX-650-23 showed an additive anti-proliferative effect, consistent with the hypothesis that niclosamide and XX-650-23 regulate the same targets or pathways to inhibit proliferation and survival of AML cells. Niclosamide significantly inhibited the progression of disease in AML patient-derived xenograft (PDX) mice, and prolonged survival of PDX mice. Niclosamide also showed synergistic effects with chemotherapy drugs to inhibit AML cell proliferation. While chemotherapy antagonized the cytotoxic potential of niclosamide, pretreatment with niclosamide sensitized cells to chemotherapeutic drugs, cytarabine, daunorubicin, and vincristine. Therefore, our results demonstrate niclosamide as a potential drug to treat AML by inducing apoptosis and cell cycle arrest through inhibition of CREB-dependent pathways in AML cells.

Small molecule screen for inhibitors of expression from canonical CREB response element-containing promoters

The transcription factor CREB (cAMP Response Element Binding Protein) is an important determinant in the growth of Acute Myeloid Leukemia (AML) cells. CREB overexpression increases AML cell growth by driving the expression of key regulators of apoptosis and the cell cycle. Conversely, CREB knockdown inhibits proliferation and survival of AML cells but not normal hematopoietic cells. Thus, CREB represents a promising drug target for the treatment of AML, which carries a poor prognosis. In this study, we performed a high-throughput small molecule screen to identify compounds that disrupt CREB function in AML cells. We screened ∼114,000 candidate compounds from Stanford University's small molecule library, and identified 5 molecules that inhibit CREB function at micromolar concentrations, but are non-toxic to normal hematopoietic cells. This study suggests that targeting CREB function using small molecules could provide alternative approaches to treat AML.

Simple uterovaginal anastomosis for cervicovaginal atresia diagnosed by magnetic resonance imaging: A report of two cases

This report describes the use of a simple transvaginal surgical method to connect the uterus with the lower vagina in patients with cervicovaginal atresia. We report two girls presenting with primary amenorrhea and cyclic abdominal pain. The girls had similar magnetic resonance imaging findings that revealed markedly enlarged uteri containing blood and no structures resembling a cervix or upper vagina. We performed transvaginal uterovaginal anastomosis with no perioperative or postoperative complications. After surgery, the patients had regular menstrual cycles and one started sexual activities with no complaints. The remarkable finding was the natural increase in the vaginal depth after surgery. This simplified transvaginal uterovaginal anastomosis technique, with its promising anatomical results, might be a treatment for cervicovaginal atresia. © 2016 Japan Society of Obstetrics and Gynecology.

Replication factor C3 is a CREB target gene that regulates cell cycle progression through the modulation of chromatin loading of PCNA

CREB (cyclic AMP response element-binding protein) is a transcription factor overexpressed in normal and neoplastic myelopoiesis and regulates cell cycle progression, although its oncogenic mechanism has not been well characterized. Replication factor C3 (RFC3) is required for chromatin loading of proliferating cell nuclear antigen (PCNA) which is a sliding clamp platform for recruiting numerous proteins in the DNA metabolism. CREB1 expression, which was activated by E2F, was coupled with RFC3 expression during the G1/S progression in the KG-1 acute myeloid leukemia (AML) cell line. There was also a direct correlation between the expression of RFC3 and CREB1 in human AML cell lines as well as in the AML cells from the patients. CREB interacted directly with the CRE site in RFC3 promoter region. CREB-knockdown inhibited primarily G1/S cell cycle transition by decreasing the expression of RFC3 as well as PCNA loading onto the chromatin. Exogenous expression of RFC3 was sufficient to rescue the impaired G1/S progression and PCNA chromatin loading caused by CREB knockdown. These studies suggest that RFC3 may have a role in neoplastic myelopoiesis by promoting the G1/S progression and its expression is regulated by CREB.

A unique carboxyl-terminal insert domain in the hematopoietic-specific, GTPase-deficient Rho GTPase RhoH regulates post-translational processing

RhoH is a hematopoietic-specific, GTPase-deficient member of the Rho GTPase family that was first identified as a hypermutable gene in human B lineage lymphomas. RhoH remains in a constitutively active state and thus its effects are regulated by expression levels or post-translational modifications. Similar to other small GTPases, intracellular localization of RhoH is dependent upon the conserved "CAAX" box and surrounding sequences within the carboxyl (C) terminus. However, RhoH also contains a unique C-terminal "insert" domain of yet undetermined function. RhoH serves as adaptor molecule in T cell receptor signaling and RhoH expression correlates with the unfavorable prognostic marker ZAP70 in human chronic lymphocytic leukemia. Disease progression is attenuated in a Rhoh(-/-) mouse model of chronic lymphocytic leukemia and treatment of primary human chronic lymphocytic leukemia cells with Lenalidomide results in reduced RhoH protein levels. Thus, RhoH is a potential therapeutic target in B cell malignancies. In the current studies, we demonstrate that deletion of the insert domain (LFSINE) results in significant cytoplasmic protein accumulation. Using inhibitors of degradation pathways, we show that LFSINE regulates lysosomal RhoH uptake and degradation via chaperone-mediated autophagy. Whereas the C-terminal prenylation site is critical for ZAP70 interaction, subcellular localization and rescue of the Rhoh(-/-) T cell defect in vivo, the insert domain appears dispensable for these functions. Taken together, our findings suggest that the insert domain regulates protein stability and activity without otherwise affecting RhoH function.

Epigenetic regulation of NANOG by miR-302 cluster-MBD2 completes induced pluripotent stem cell reprogramming

While most somatic cells undergoing induced pluripotent stem (iPS) cell reprogramming with Yamanaka factors accumulate at stable partially reprogrammed stages, the molecular mechanisms required to achieve full reprogramming are unknown. MicroRNAs (miRNAs) fine-tune mRNA translation and are implicated in reprogramming, but miRNA functional targets critical for complete iPS cell reprogramming remain elusive. We identified methyl-DNA binding domain protein 2 (MBD2) as an epigenetic suppressor, blocking full reprogramming of somatic to iPS cells through direct binding to NANOG promoter elements preventing transcriptional activation. When we overexpressed miR-302 cluster we observed a significant increase in conversion of partial to fully reprogrammed iPS cells by suppressing MBD2 expression, thereby increasing NANOG expression. Thus, expression of exogenous miR-302 cluster (without miR-367) is efficient in attaining a fully reprogrammed iPS state in partially reprogrammed cells by relieving MBD2-mediated inhibition of NANOG expression. Our studies provide a direct molecular mechanism involved in generating complete human iPS cell reprogramming to study disease pathogenesis, drug screening, and for potential cell-based therapies.

Identification of a novel anti-apoptotic E3 ubiquitin ligase that ubiquitinates antagonists of inhibitor of apoptosis proteins SMAC, HtrA2, and ARTS

Identification of new anti-apoptotic genes is important for understanding the molecular mechanisms underlying apoptosis and tumorigenesis. The present study identified a novel anti-apoptotic gene named AREL1, which encodes a HECT (homologous to E6-AP carboxyl terminus) family E3 ubiquitin ligase. AREL1 interacted with and ubiquitinated IAP antagonists such as SMAC, HtrA2, and ARTS. However, AREL1 was cytosolic and did not localize to nuclei or mitochondria. The interactions between AREL1 and the IAP antagonists were specific for apoptosis-stimulated cells, in which the IAP antagonists were released into the cytosol from mitochondria. Furthermore, the ubiquitination and degradation of SMAC, HtrA2, and ARTS were significantly enhanced in AREL1-expressing cells following apoptotic stimulation, indicating that AREL1 binds to and ubiquitinates cytosolic but not mitochondria-associated forms of IAP antagonists. Furthermore, the anti-apoptotic role of AREL1-mediated degradation of SMAC, HtrA2, and ARTS was shown by simultaneous knockdown of three IAP antagonists, which caused the inhibition of caspase-3 cleavage, XIAP degradation, and induction of apoptosis. Therefore, the present study suggests that AREL1-mediated ubiquitination and degradation of cytosolic forms of three IAP antagonists plays an important role in the regulation of apoptosis.

p53 and DNA-dependent protein kinase catalytic subunit independently function in regulating actin damage-induced tetraploid G1 arrest

We previously reported that the p53 tumor suppressor protein plays an essential role in the induction of tetraploid G1 arrest in response to perturbation of the actin cytoskeleton, termed actin damage. In this study, we investigated the role of p53, ataxia telangiectasia mutated protein (ATM), and catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) in tetraploid G1 arrest induced by actin damage. Treatment with actin-damaging agents including pectenotoxin-2 (PTX-2) increases phosphorylation of Ser-15 and Ser-37 residues of p53, but not Ser-20 residue. Knockdown of ATM and DNA-PKcs do not affect p53 phosphorylation induced by actin damage. However, while ATM knockdown does not affect tetraploid G1 arrest, knockdown of DNA-PKcs not only perturbs tetraploid G1 arrest, but also results in formation of polyploidy and induction of apoptosis. These results indicate that DNA-PKcs is essential for the maintenance of actin damage induced-tetraploid G1 arrest in a p53-independent manner. Furthermore, actin damage-induced p53 expression is not observed in cells synchronized at G1/S of the cell cycle, implying that p53 induction is due to actin damage-induced tetraploidy rather than perturbation of actin cytoskeleton. Therefore, these results suggest that p53 and DNA-PKcs independently function for tetraploid G1 arrest and preventing polyploidy formation.

5-Aminoimidazole-4-carboxyamide ribonucleoside induces G(1)/S arrest and Nanog downregulation via p53 and enhances erythroid differentiation

Molecular mechanisms of how energy metabolism affects embryonic stem cell (ESC) pluripotency remain unclear. AMP-activated protein kinase (AMPK), a key regulator for controlling energy metabolism, is activated in response to ATP-exhausting stress. We investigated whether cellular energy homeostasis is associated with maintenance of self-renewal and pluripotency in mouse ESCs (mESCs) by using 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR) as an activator of AMPK. We demonstrate that AICAR treatment activates the p53/p21 pathway and markedly inhibits proliferation of R1 mESCs by inducing G(1) /S-phase cell cycle arrest, without influencing apoptosis. Treatment with AICAR also significantly reduces pluripotent stem cell markers, Nanog and stage-specific embryonic antigen-1, in the presence of leukemia inhibitory factor, without affecting expression of Oct4. H9 human ESCs also responded to AICAR with induction of p53 activation and repression of Nanog expression. AICAR reduced Nanog mRNA levels in mESCs transiently, an effect not due to expression of miR-134 which can suppress Nanog expression. AICAR induced Nanog degradation, an effect inhibited by MG132, a proteasome inhibitor. Although AICAR reduced embryoid body formation from mESCs, it increased expression levels of erythroid cell lineage markers (Ter119, GATA1, Klf1, Hbb-b, and Hbb-bh1). Although erythroid differentiation was enhanced by AICAR, endothelial lineage populations were remarkably reduced in AICAR-treated cells. Our results suggest that energy metabolism regulated by AMPK activity may control the balance of self-renewal and differentiation of ESCs.

NF-Y binds to both G1- and G2-specific cyclin promoters; a possible role in linking CDK2/Cyclin A to CDK1/Cyclin B

We previously reported that CDK2/Cyclin A can phosphorylate and activate the transcription factor NF-Y. In this study, we investigated a potential regulatory role for NF-Y in the transcription of Cyclin A and other cell cycle regulatory genes. Gel-shift assays demonstrate that NF-Y binds to CCAAT sequences in the Cyclin A promoter, as well as to those in the promoters of cell cycle G2 regulators such as CDC2, Cyclin B and CDC25C. Furthermore, expression of Cyclin A increases NF-Y's affinity for CCAAT sequences in the CDC2 promoter; however, Cyclin A's induction of CDC2 transcription is antagonized by p21, an inhibitor of CDK2/Cyclin A. These results suggest a model wherein NF-Y binds to and activates transcription from the Cyclin A promoter, increasing cellular levels of Cyclin A/CDK2 and potentiating NF-Y's capacity for transcriptional transactivation, and imply a positive feedback loop between NF-Y and Cyclin A/CDK2. Our findings are additionally indicative of a role for Cyclin A in activating Cyclin B/CDK1 through promoting NF-Y dependent transcription of Cyclin B and CDC2; NF-Y mediated crosstalk may therefore help to orchestrate cell-cycle progression.

SIRT1 deficiency downregulates PTEN/JNK/FOXO1 pathway to block reactive oxygen species-induced apoptosis in mouse embryonic stem cells

Silent mating type information regulation 2 homolog 1 (SIRT1) plays a critical role in reactive oxygen species-triggered apoptosis in mouse embryonic stem (mES) cells. Here, we investigated a possible role for the PTEN/Akt/JNK pathway in the SIRT1-mediated apoptosis pathway in mES cells. Akt was activated by removal of anti-oxidant 2-mercaptoethanol in SIRT1(-/-) mES cells. Since PTEN is a negative regulator of Akt and its activity can be modulated by acetylation, we investigated if SIRT1 deacetylated PTEN to downregulate Akt to trigger apoptosis in anti-oxidant-free culture conditions. PTEN was hyperacetylated and excluded from the nucleus in SIRT1(-/-) mES cells, consistent with enhanced Akt activity. SIRT1 deficiency enhanced the acetylation/phosphorylation level of FOXO1 and subsequently inhibited the nuclear localization of FOXO1. Cellular acetylation levels were enhanced by DNA-damaging agent, not by removal of anti-oxidant. c-Jun NH2-terminal kinase (JNK) was activated by removal of anti-oxidant in SIRT1-dependent manner. Although p53 acetylation was stronger in SIRT1(-/-) mES cells, DNA-damaging stress activated phosphorylation and enhanced cellular levels of p53 irrespective of SIRT1, whereas removal of anti-oxidant slightly activated p53 only with SIRT1. Expression levels of Bim and Puma were increased in anti-oxidant-free culture conditions in an SIRT1-dependent manner and treatment with JNK inhibitor blocked induction of Bim expression. DNA-damaging agent activated caspase3 regardless of SIRT1. Our data support an important role for SIRT1 in preparing the PTEN/JNK/FOXO1 pathway to respond to cellular reactive oxygen species.

RhoH regulates subcellular localization of ZAP-70 and Lck in T cell receptor signaling

RhoH is an hematopoietic-specific, GTPase-deficient Rho GTPase that plays a role in T development. We investigated the mechanisms of RhoH function in TCR signaling. We found that the association between Lck and CD3ζ was impaired in RhoH-deficient T cells, due to defective translocation of both Lck and ZAP-70 to the immunological synapse. RhoH with Lck and ZAP-70 localizes in the detergent-soluble membrane fraction where the complex is associated with CD3ζ phosphorylation. To determine if impaired translocation of ZAP-70 was a major determinant of defective T cell development, Rhoh(-/-) bone marrow cells were transduced with a chimeric myristoylation-tagged ZAP-70. Myr-ZAP-70 transduced cells partially reversed the in vivo defects of RhoH-associated thymic development and TCR signaling. Together, our results suggest that RhoH regulates TCR signaling via recruitment of ZAP-70 and Lck to CD3ζ in the immunological synapse. Thus, we define a new function for a RhoH GTPase as an adaptor molecule in TCR signaling pathway.

Rac guanosine triphosphatases represent integrating molecular therapeutic targets for BCR-ABL-induced myeloproliferative disease

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disease (MPD) initiated by expression of the p210-BCR-ABL fusion protein. We demonstrate in a murine model of p210-BCR-ABL-induced MPD that gene targeting of Rac1 and Rac2 significantly delays or abrogates disease development. Attenuation of the disease phenotype is associated with severely diminished p210-BCR-ABL-induced downstream signaling in primary hematopoietic cells. We utilize NSC23766, a small molecule antagonist of Rac activation, to validate biochemically and functionally Rac as a molecular target in both a relevant animal model and in primary human CML cells in vitro and in a xenograft model in vivo, including in Imatinib-resistant p210-BCR-ABL disease. These data demonstrate that Rac is an additional therapeutic target in p210-BCR-ABL-mediated MPD.

RhoH GTPase recruits and activates Zap70 required for T cell receptor signaling and thymocyte development

RhoH is a hematopoietic-specific, GTPase-deficient member of the Rho GTPase family with unknown physiological function. Here we demonstrate that Rhoh-/- mice have impaired T cell receptor (TCR)-mediated thymocyte selection and maturation, resulting in T cell deficiency. RhoH deficiency resulted in defective CD3zeta phosphorylation, impaired translocation of the signaling molecule Zap70 to the immunological synapse and reduced activation of Zap70-mediated signaling in thymic and peripheral T cells. Proteomic analyses demonstrated that RhoH is a component of TCR signaling and is required for recruitment of Zap70 to the TCR through interaction with RhoH noncanonical immunoreceptor tyrosine-based activation motifs (ITAMs). In vivo reconstitution studies also demonstrated that RhoH function depends on phosphorylation of the RhoH ITAMs. These findings suggest that RhoH is a critical regulator of thymocyte development and TCR signaling by mediating recruitment and activation of Zap70.

Rhythmic serotonin N-acetyltransferase mRNA degradation is essential for the maintenance of its circadian oscillation

Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase [AANAT]) is the key enzyme in melatonin synthesis regulated by circadian rhythm. To date, our understanding of the oscillatory mechanism of melatonin has been limited to autoregulatory transcriptional and posttranslational regulations of AANAT mRNA. In this study, we identify three proteins from pineal glands that associate with cis-acting elements within species-specific AANAT 3' untranslated regions to mediate mRNA degradation. These proteins include heterogeneous nuclear ribonucleoprotein R (hnRNP R), hnRNP Q, and hnRNP L. Their RNA-destabilizing function was determined by RNA interference and overexpression approaches. Expression patterns of these factors in pineal glands display robust circadian rhythm. The enhanced levels detected after midnight correlate with an abrupt decline in AANAT mRNA level. A mathematical model for the AANAT mRNA profile and its experimental evidence with rat pinealocytes indicates that rhythmic AANAT mRNA degradation mediated by hnRNP R, hnRNP Q, and hnRNP L is a key process in the regulation of its circadian oscillation.

Oocyte-based screening of cytokinesis inhibitors and identification of pectenotoxin-2 that induces Bim/Bax-mediated apoptosis in p53-deficient tumors

In this study, we demonstrate that a loss of p53 sensitizes tumor cells to actin damage. Using a novel oocyte-based screening system, we identified natural compounds that inhibit cytokinesis. Among these, pectenotoxin-2 (PTX-2), which was first identified as a cytotoxic entity in marine sponges, which depolymerizes actin filaments, was found to be highly effective and more potent to activate an intrinsic pathway of apoptosis in p53-deficient tumor cells compared to those with functional p53 both in vitro and in vivo. Other agents that depolymerize or knot actin filaments were also found to be toxic to p53-deficient tumors. In p53-deficient cells, PTX-2 triggers apoptosis through mitochondrial dysfunction, and this is followed by the release of proapoptotic factors and caspase activation. Furthermore, we observed Bax activation and Bim induction only in p53-deficient cells after PTX-2 treatment. RNA interference of either Bim or Bax resulted in the inhibition of caspases and apoptosis induced by PTX-2. However, the small interfering RNAs (SiRNA) of Bim blocked a conformational change of Bax, but Bax SiRNA did not affect Bim expression. Therefore, these results suggest that Bim triggers apoptosis by activating Bax in p53-deficient tumors upon actin damage, and that actin inhibitors may be potent chemotherapeutic agents against p53-deficient tumors.

Protein kinase C regulates the activity and stability of serotonin N-acetyltransferase

Effects of protein kinase C on protein stability and activity of rat AANAT were investigated in vitro and in vivo. When COS-7 cells transfected with AANAT cDNA were treated with phorbol 12-myristate 13-acetate (PMA), both the activity and protein level of AANAT were increased. These effects of PMA were blocked by GF109203X, a specific inhibitor of PKC. Moreover, PMA increased the phosphorylation of AANAT and induced the formation of AANAT/14-3-3zeta complex. PMA did not affect the basal level of cAMP and did not involve the potentiation of the cAMP production by forskolin, indicating that PKC-dependent activation of adenylyl cyclase was excluded in transfected COS-7 cells. To identify which amino acids were phosphorylated by PKC, several conserved Thr and Ser residues in AANAT were targeted for site-directed mutagenesis. Mutations of Thr29 and Ser203 prevented the increase of enzymatic activity and protein level mediated by PMA. To explore the nature of AANAT phosphorylation, purified rat AANAT was subjected to in vitro PKC kinase assay. PKC directly phosphorylated the rat recombinant AANAT. The phosphopeptides identified by mass spectrometric analysis, and western blotting indicated that Thr29 was one of target sites for PKC. To confirm the effects of the physiological activation of PKC, rat pineal glands were treated with alpha(1)-adrenergic specific agonist phenylephrine. Phenylephrine caused the phosphorylation of endogenous AANAT whereas GF109203X or prazosin, an alpha(1)-adrenergic-specific antagonist, markedly inhibited it. These results suggest that AANAT was phosphorylated at Thr29 by PKC activation through the alpha(1)-adrenergic receptor in rat pineal glands, and that its phosphorylation might contribute to the stability and the activity of AANAT.

Cdk2-dependent phosphorylation of the NF-Y transcription factor is essential for the expression of the cell cycle-regulatory genes and cell cycle G1/S and G2/M transitions

We previously reported that cdk2 phosphorylates two serine residues near the DNA-binding domain of the YA subunit of NF-Y transcription factor and this phosphorylation is essential for DNA binding of NF-Y. In this study, we examined the effects of a phosphorylation-deficient mutant form of YA, YA-aa, in which the two serine residues are replaced with alanine, on the cell cycle and expression of the NF-Y target genes. Transient transfection assays show that YA-aa inhibits transcription from the NF-Y target promoters, such as cdc2, cyclin A, and cdc25C. Moreover, this inhibitory function of YA-aa can be suppressed by the expression of wild-type YA, implying that YA-aa inhibits transcription of those NF-Y target genes by inactivating wild-type YA. Since NF-Y target genes include the cell cycle-regulatory genes that ensure orderly progression of the cell cycle, we examined the effects of YA-aa in cell cycle progression. We constructed a recombinant adenovirus encoding YA-aa and found that YA-aa expression leads to repression of cell cycle-regulatory genes, such as cyclin A, RNR R2, DNA polymerase alpha, cdc2, cyclin B, and cdc25C. Consistently, YA-aa expression results in the inactivation of both cdc2 and cdk2. Furthermore, cell cycle analysis reveals that YA-aa induces cell cycle arrest at both G1 and G2/M. These results suggest that cdk2-dependent phosphorylation of NF-Y is essential for the expression of the cell cycle-regulatory genes and therefore for cell cycle progression at both G1/S and G2/M.

Bcl-xL and E1B-19K proteins inhibit p53-induced irreversible growth arrest and senescence by preventing reactive oxygen species-dependent p38 activation

In this study, we describe novel functions of the anti-apoptotic Bcl-2 family proteins. Bcl-x(L) and E1B-19K were found to inhibit p53-induced irreversible growth arrest and senescence, but not to inhibit transient growth arrest, implying that Bcl-x(L) and E1B-19K are specifically involved in senescence without participating in growth arrest. We provide several lines of evidences showing that the functions of Bcl-x(L) and E1B-19K to prevent generation of reactive oxygen species (ROS) are important to inhibit senescence induction. First, we found that that ROS are increased during p53-induced senescence. Moreover, Bcl-x(L) and E1B-19K inhibit this p53-induced ROS generation. Second, antioxidants prevent the induction of senescence and ROS by p53, but not the persistence of the senescence phenotype. Third, the anti-senescence functions of Bcl-x(L) and E1B-19K were suppressed by adding exogenous ROS. These results suggest that Bcl-x(L) and E1B-19K inhibit senescence induction by preventing ROS generation. Furthermore, p38 kinase was found to be activated during p53-induced senescence, but not in cells expressing Bcl-x(L) or E1B-19K, or in cells treated with anti-oxidants. Consistently, a chemical inhibitor of p38 kinase, SB203580, was found to inhibit p53-induced senescence, but only when treated before the cellular commitment to senescence, implying that p38 kinase is necessary for senescence induction. Therefore, Bcl-x(L) and E1B-19K inhibit p53-induced senescence by preventing ROS generation, which in turn leads to the activation of p38 kinase. These results also suggest that the oncogenic potential of Bcl-2 is due to its ability to inhibit senescence as well as apoptosis.

Cdk2-dependent phosphorylation of the NF-Y transcription factor and its involvement in the p53-p21 signaling pathway

Recent studies have suggested that the NF-Y transcription factor is involved in transcription repression of the cell cycle regulatory genes in a response to p53 induction or DNA damage. Here we demonstrate the cdk2-dependent phosphorylation of NF-Y and its involvement in transcription repression by the p53-p21 signaling pathway. Cdk2 phosphorylates two serine residues near the DNA-binding domain of the YA subunit of NF-Y. Cyclin A-cdk2 appears to associate with NF-Y both in vitro and in vivo. Furthermore, YA protein is phosphorylated in parallel with a cell cycle-dependent activation of cdk2 kinase and cyclin A expression. YA phosphorylation is unnecessary for heterotrimer formation with the YB-YC dimer. However, NF-Y containing a phosphorylation-deficient mutant form of YA, YA-aa, has its DNA binding activity impaired. Consistently, YA-aa inhibits transcription activation of a NF-Y target promoter, cdc2, by cdk2. These results facilitate the elucidation of the regulatory mechanisms of cell cycle progression involving the p21-cdk2-NF-Y signaling pathway.

Increased expression of endoglin in the eutopic endometrium of women with endometriosis

OBJECTIVE

To compare the angiogenic activities of endothelial cells in the eutopic endometrium of women with and without endometriosis.

DESIGN

Vessels with active angiogenesis were identified using the monoclonal antibody to endoglin.

SETTING

University department of obstetrics and gynecology.

PATIENT(S)

Twenty women with histologically confirmed endometriosis after laparotomy or laparoscopy. Women with carcinoma in situ of uterine cervix, but no evidence of endometriosis (n = 20), served as control subjects.

INTERVENTION(S)

Formalin-fixed, paraffin-embedded archival tissues were sectioned and stained.

MAIN OUTCOME MEASURE(S)

Number of vessels stained with monoclonal antibody to endoglin.

RESULT(S)

For all menstrual phases, the mean number of vessels with endoglin expression was significantly greater in patients with endometriosis compared with control subjects. In each menstrual phase, a significant difference was observed only during the late secretory phase. Within the group with endometriosis, the mean numbers of vessels with endoglin expression in stages I and II were not different from the numbers in stages III and IV.

CONCLUSION(S)

This study shows the expression of endoglin in the eutopic endometrium of women with endometriosis is significantly increased and the increase is observed only in the late secretory phase. It is suggested from these findings that activation of angiogenesis in the eutopic endometrium might be a key factor in the pathogenesis of endometriosis.

Potentiation of PGE(2)-mediated cAMP production during neuronal differentiation of human neuroblastoma SK-N-BE(2)C cells

The prostaglandin-evoked cAMP production was studied in human neuroblastoma SK-N-BE(2)C cells during neuronal differentiation induced by all-trans retinoic acid. The incubation with 5 microM all-trans retinoic acid for 4-6 days promoted neurite outgrowth of cells. After differentiation, prostaglandin E(2) (PGE(2))-induced cAMP production was dramatically increased, whereas forskolin- and AlF-induced cAMP productions were not changed. The increase reached maximum after 4-days of incubation with all-trans retinoic acid. The differentiation caused an increase in the maximal response and a decrease in the half-maximal effective concentration of the PGE(2)-induced cAMP production. In addition, the binding of [(3)H]PGE(2) to membrane receptors was enhanced in differentiated cells. However, the order of potency of the various prostaglandins (PGE(1) = PGE(2) > PGD(2) = PGF(2alpha) = PGI(2)) in cAMP production did not change during the differentiation, suggesting that mainly E-prostanoid (EP) receptors were involved. Butaprost, an EP(2) receptor specific agonist, increased the cAMP level in a concentration dependent manner and had a similar potentiating effect on cAMP production as PGE(2) upon differentiation. Northern blot analysis using the human cDNA probes shows that the EP(2) mRNA level was about seven times higher in differentiated cells, while the dopamine beta-hydroxylase (DBH) mRNA completely disappeared. Our results, thus, suggest that elevated gene expression of the prostanoid EP(2) receptor results in an increase in the PGE(2)-evoked cAMP production in SK-N-BE(2)C cells during neuronal differentiation.

p53 and its homologues, p63 and p73, induce a replicative senescence through inactivation of NF-Y transcription factor

Recent studies have identified two p53 homologues, p63 and p73. They activate p53-responsive promoters and induce apoptosis when overexpressed in certain human tumors. Here, we report that p63, like p53 and p73, induces replicative senescence when expressed in a tetracycline-regulated manner in EJ cells lacking a functional p53. In addition to transcription activation of p53-responsive genes, we found that p63 and p73 repress transcription of the cdk1 and cyclin B genes, both of which are irreversibly repressed in senescent human fibroblast. In transient transfection assay, p63 and p73 repress the cdk1 promoter regardless of the presence of a dominant negative mutant form of p53. Furthermore, we found that DNA binding activity of NF-Y transcription factor, which is essential for transcription of the cdk1 and cyclin B genes and inactivated in senescent fibroblast, is significantly decreased by expression of either of p53, p63, or p73. Since NF-Y binds to many promoters besides the cdk1 and cyclin B promoters, inactivation of NF-Y by p53 family genes may be a general mechanism for transcription repression in replicative senescence.

Ovarian hyperstimulation syndrome complicating a spontaneous singleton pregnancy: a case report

It has been known that most cases of ovarian hyperstimulation syndrome (OHSS) are associated with the use of exogenous gonadotropins to induce multiple ovulation. However, OHSS is infrequently associated with a spontaneous ovulatory cycle, usually in the case of multiple gestations, hypothyroidism, or polycystic ovarian syndrome. We report a case of severe OHSS in a spontaneously pregnant woman with no underlying disease.

Relationship between endometrial estrogen and progesterone receptors, and sonographic endometrial appearance in the preovulatory phase

OBJECTIVES

The purpose of the present study is to evaluate the relationship between endometrial concentrations of estrogen receptor (ER) and progesterone receptor (PR), and sonographic endometrial findings in the preovulatory phase of menstrual cycle.

STUDY DESIGN

In 45 cycles of 45 infertile women with tubal factor only, transvaginal sonographic assessments and biopsy for immunohistochemical staining of the endometrium were made in the preovulatory phase of unstimulated, normal menstrual cycle. Immunohistochemical localization of ER and PR was scored according to intensity of staining and proportion of cells specifically stained in glandular epithelium and stroma, and the results were analysed according to the sonographic endometrial thickness (< 6 mm, 6-10 mm, or > 10 mm) and patterns. Endometrial patterns were classified as A, centrally hyperechogenic triple-line pattern or non-A, not triple-line.

RESULTS

There were no significant differences in the endometrial thickness, serum estradiol level and serum progesterone level between A and non-A groups. The receptor scores of epithelial and stromal ER and epithelial PR were comparable in A and non-A groups. However, the receptor score of stromal PR was significantly higher in A group, with 4.8 +/- 1.4 compared with 2.7 +/- 1.7 in non-A group (p < 0.001). There were no differences in the receptor scores of epithelial ER, epithelial PR, stromal ER and stromal PR among the 3 groups according to the endometrial thickness.

CONCLUSIONS

This study suggests that high PR expression in endometrial stroma could be related to the sonographic triple-line or multilayered pattern of endometrium in the preovulatory period.

Constitutive activation of cyclin B1-associated cdc2 kinase overrides p53-mediated G2-M arrest

Recent studies have suggested that p53 regulates the G2 checkpoint in the cell cycle and that this function is required for the maintenance of genomic integrity. In this study, we investigated a regulatory role of p53 specifically in G2-M transition. Human bladder carcinoma cells lacking functional p53 were synchronized at G1-S, which is preceded by p53-mediated G1 arrest. p53 expression in the synchronized cells was induced by infection with a recombinant adenovirus that encodes p53. After release from the G1-S arrest, the cells progressed to S-phase and G2 but failed to enter mitosis. Biochemical analysis showed that p53 inhibits cell cycle-dependent expression of cdc2 and cyclin B1 and consequently inhibits cdc2 kinase. The role of cyclin B1-associated cdc2 kinase in p53-mediated G2-M arrest was further investigated by expression of both cyclin B1 and cdc2AF, in which inhibitory phosphorylation sites were substituted. The cells expressing both cdc2AF and cyclin B1 showed a constitutive activation of cdc2 kinase during cell cycle progression and passed through G2-M regardless of p53 expression. Therefore, inactivation of cdc2 kinase through cdc2 and cyclin B1 repression is an essential step in p53-mediated G2-M arrest.

Clinical usefulness of basal FSH as a prognostic factor in patients undergoing intracytoplasmic sperm injection

OBJECTIVE

To determine if basal serum follicle stimulating hormone (FSH) level could be a prognostic factor of the clinical outcome in intracytoplasmic sperm injection (ICSI) cycles in the couples with male factor infertility.

MATERIALS AND METHODS

From December 1995 to March 1998, total 118 patients underwent in vitro fertilization and embryo transfer (IVF-ET) with ICSI due to male factor infertility were included in this study. Patients were allocated to the low basal FSH group (< 8.5 mIU/ml) and the high basal FSH group (> or = 8.5 mIU/ml). The basal levels of FSH were measured in the 3rd day of menstrual cycle preceding ovarian stimulation cycle in total IVF cycles by immunoradiometric assay (IRMA). Statistical analysis was performed using Student's t-test, Fisher's exact test, and chi 2 test as appropriate. Statistical significance was defined as p < 0.05.

RESULTS

The total dose of exogeneous gonadotropin required in the high basal FSH group was significantly higher than that in the low basal FSH group. The numbers of retrieved oocytes and oocytes with grade I, II were significantly higher in the low basal FSH group. The clinical pregnancy rate per cycle in the low basal FSH group (16.2%) was significantly higher than that in the high basal FSH group (4.0%).

CONCLUSION

These results suggested that the basal serum FSH levels could be predictive of pregnancy outcome and the results of controlled ovarian hyperstimulation (COH) in ICSI cycles.

Rapid and simple measurement of serotonin N-acetyltransferase activity by liquid biphasic diffusion assay

We report here a rapid, simple, and accurate method to assay for serotonin N-acetyltransferase (NAT) activity. This assay relies on the selective diffusion of radiolabeled acetyltryptamine into a water-immiscible scintillation fluid. Unlike organic solvent extraction, thin-layer chromatography, or high performance liquid chromatography, the separation of acetyltryptamine from acetyl CoA and tryptamine is not required in the method. Moreover, the limit of sensitivity is less than 4 pmol of N-acetyltryptamine formed per sample. Enhancement of NAT activity upon beta-adrenergic receptor stimulation in the rat pineal gland was clearly detected with this method. In addition, the NAT activity measurements obtained with this method agreed quantitatively in the pineal gland and other brain tissues with the conventional organic solvent extraction method. The results suggest that this liquid biphasic diffusion assay is applicable to the detection of NAT activity in tissues and cells.

p53 negatively regulates cdc2 transcription via the CCAAT-binding NF-Y transcription factor

The p53 tumor suppressor protein regulates the transcription of regulatory genes involved in cell cycle arrest and apoptosis. We have reported previously that inducible expression of the p53 gene leads to the cell cycle arrest both at G(1) and G(2)/M in association with induction of p21 and reduction of mitotic cyclins (cyclin A and B) and cdc2 mRNA. In this study, we investigated the mechanism by which p53 regulates transcription of the cdc2 gene. Transient transfection analysis showed that wild type p53 represses whereas various dominant negative mutants of p53 increase cdc2 transcription. The cdc2 promoter activity is not repressed in cells transfected with a transactivation mutant, p53(22/23). An adenovirus oncoprotein, E1B-55K inhibits the p53-mediated repression of the cdc2 promoter, while E1B-19K does not. Since the cdc2 promoter does not contain a TATA sequence, we performed deletion and point mutation analyses and identified the inverted CCAAT sequence located at -76 as a cis-acting element for the p53-mediated regulation. We found that a specific DNA-protein complex is formed at the CCAAT sequence and that this complex contains the NF-Y transcription factor. Consistently, a dominant negative mutant of the NF-YA subunit, NF-YAm29, decreases the cdc2 promoter, and p53 does not further decrease the promoter activity in the presence of NF-YAm29. These results suggest that p53 negatively regulates cdc2 transcription and that the NF-Y transcription factor is required for the p53-mediated regulation.

Pyridostigmine cotreatment for controlled ovarian hyperstimulation in low responders undergoing in vitro fertilization-embryo transfer

OBJECTIVE

To investigate the effect of pyridostigmine, an acetylcholinesterase inhibitor, as cotreatment for controlled ovarian hyperstimulation (COH) in low responders.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

A reproductive medicine unit in a university hospital.

PATIENT(S)

Seventy infertile women with a history of low ovarian response to COH using a GnRH agonist as part of a long stimulation protocol in previous IVF-ET cycles.

INTERVENTION(S)

Sixty milligrams of pyridostigmine or placebo was administered orally twice daily from the first day of COH until the day of hCG injection in patients undergoing IVF-ET cycles.

MAIN OUTCOME MEASURE(S)

In vitro fertilization results, pregnancy outcome, and serum and intrafollicular concentrations of GH and insulin-like growth factor-1.

RESULT(S)

Pyridostigmine cotreatment was associated with significant decreases in the amount of gonadotropins and the duration of stimulation required. The clinical pregnancy rate was higher in the pyridostigmine group, but this difference was not statistically significant (25.7% vs. 11.4%). The serum GH level on the day of hCG injection was significantly higher in the pyridostigmine group than in the placebo group. Follicular fluid concentrations of GH and insulin-like growth factor-1 were significantly higher in the pyridostigmine group.

CONCLUSION(S)

This study suggests that pyridostigmine cotreatment for COH could affect the serum and intrafollicular GH and insulin-like growth factor-1 concentrations and, hence, improve the ovarian response to COH and the results of IVF in low responders undergoing IVF-ET.

The effect of epidermal growth factor on the preimplantation development, implantation and its receptor expression in mouse embryos

OBJECTIVE

To investigate the influence of epidermal growth factor (EGF) on preimplantation development, implantation, and expression of epidermal growth factor receptor (EGFR) itself in mouse embryos.

MATERIALS AND METHOD

Eight-cell stage mouse embryos were cultured for 48 hours with EGF at concentrations of 0.1, 1.0, 10 and 100 ng/ml. Embryos not treated with EGF were served as control. The percentages of embryos which developed to the expanded, hatched blastocyst stage and in vitro implantation at 48 hours were determined. Reverse transcription-polymerase chain reaction (RT-PCR) has been used to examine the expression of EGFR in developed hatched blastocysts. Following reverse transcription, strategically designed nested primers, optimized for specificity, were used for amplification from the cDNA equivalent of a single embryo. The products were then verified by restriction enzyme digestion and sequence analysis. Results were analyzed with chi 2 test and Student's t-test as appropriate, and statistical significance was defined as p < 0.05.

RESULTS

The percentages of fully expanded blastocysts at 48 hours in all the EGF treated group were not significantly different from the control. The percentages of hatched blastocysts were significantly higher in the EGF treatment group at 0.1 ng/ml (90.5 +/- 9.8%) compared to the control (82.1 +/- 7.2%), 1.0 ng/ml (82.2 +/- 12.7%), and 100 mg/ml (81.9 +/- 11.8%) (p < 0.05, p < 0.05, p < 0.05, respectively). The percentages of hatched blastocysts were significantly higher in the EGF treatment group at 10 ng/ml (89.4 +/- 7.5%) compared to the control, and 100 ng/ml (p < 0.05, p < 0.05, respectively). The percentages of attached blastocysts in vitro were significantly higher following incubation with EGF at concentrations of 0.1 ng/ml (37.0 +/- 17.0%), 1.0 ng/ml (32.0 +/- 14.3%), 10 ng/ml (21.3 +/- 7.2%) compared to the control (9.5 +/- 7.7%) (p < 0.05, p < 0.05, p < 0.05, respectively). The attachment rates in 0.1 ng/ml and 1.0 ng/ml EGF treatment groups were also significantly higher than those in other EGF treatment groups. Embryo development and attachment were not significantly inhibited or enhanced in cultures supplemented with 100 ng/ml EGF compared to the control. The mRNA concentration of EGFR in embryos treated with 0.1 ng/ml of EGF was significantly higher than those of the control and other EGF treatment groups.

CONCLUSION

EGF may have a stimulatory role in later stage embryonic development, implantation and expression of EGFR in hatched blastocyst itself at the specific concentration.

Characterization of high affinity neurotensin receptor NTR1 in HL-60 cells and its down regulation during granulocytic differentiation

1. We investigated responses to neurotensin in human promyelocytic leukaemia HL-60 cells. 2. Neurotensin increased the cytosolic calcium concentration ([Ca2+]i) in a concentration-dependent manner and also produced inositol 1,4,5-trisphosphate (InsP3). 3. Among the tested neurotensin analogues, neurotensin 8-13, neuromedin-N, and xenopsin also increased [Ca2+]i, whereas neurotensin 1-11 and neurotensin 1-8 did not elicit detectable responses. 4. SR48692, an antagonist of NTR1 neurotensin receptors, blocked the neurotensin-induced [Ca2+]i increase, whereas levocabastine, which is known as an NTR2 neurotensin receptor antagonist, did not attenuate the neurotensin-evoked effect. 5. The expression of NTR1 neurotensin receptors was confirmed by Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR). 6. During 1.25% dimethylsulfoxide (DMSO)-triggered granulocytic differentiation of HL-60 cells, the neurotensin-induced [Ca2+]i rise became gradually smaller and completely disappeared 4 days after treatment with DMSO. The mRNA level for neurotensin receptors was also decreased after differentiation. 7. The results show that HL-60 cells express NTR1 neurotensin receptors and suggest that granulocytic differentiation involves transcriptional regulation of the receptors resulting in down-regulation of the neurotensin-induced signalling.

Pharmacological characterization of beta2-adrenoceptor in PGT-beta mouse pineal gland tumour cells

1. The adrenoceptor in a mouse pineal gland tumour cell line (PGT-beta) was identified and characterized using pharmacological and physiological approaches. 2. Adrenaline and noradrenaline, adrenoceptor agonists, stimulated cyclic AMP generation in a concentration-dependent manner, but had no effect on inositol 1,4,5-trisphosphate production. Adrenaline was a more potent activator of cyclic AMP generation than noradrenaline, with half maximal-effective concentrations (EC50) seen at 175+/-22 nM and 18+/-2 microM for adrenaline and noradrenaline, respectively. 3. The addition of forskolin synergistically stimulated the adrenaline-mediated cyclic AMP generation in a concentration-dependent manner. 4. The pA2 value for the specific beta2-adrenoceptor antagonist ICI-118,551 (8.7+/-0.4) as an antagonist of the adrenaline-stimulated cyclic AMP generation were 3 units higher than the value for the betaI-adrenoceptor antagonist atenolol (5.6+/-0.3). 5. Treatment of the cells with adrenaline and forskolin evoked a 3 fold increase in the activity of serotonin N-acetyltransferase with the peak occurring 6 h after stimulation. 6. These results suggest the presence of beta2-adrenoceptors in mouse pineal cells and a functional relationship between the adenylyl cyclase system and the regulation of N-acetyltransferase expression.

Influence of antithyroid antibodies in euthyroid women on in vitro fertilization-embryo transfer outcome

PROBLEM

To investigate whether antithyroid antibodies (ATAs) affect the pregnancy outcome in euthyroid women undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHOD OF STUDY

Thyroid peroxidase antibody (TPOA) and thyroglobulin antibody (TGA) were measured by radioligand assay kits that were used as ATAs in 79 patients with tubal or unexplained infertility who were enrolled in an IVF-ET program. Women who were positive for antinuclear antibody, lupus anticoagulant, anticardiolipin antibody, and rheumatoid factor were excluded from our study. The study group comprised 28 (29.1%) euthyroid women who were positive for TPOAs, TGAs, or both. Fifty-one euthyroid women without ATAs served as control subjects. The results were analyzed with linear regression analysis, Student's t-test, Mann-Whitney U test, Kruskal-Wallis analysis of variance, chi 2 test, and Fisher's exact test.

RESULTS

There were no significant differences between the study group and the control group in patient characteristics such as age, infertility duration, and hormonal profile. There were also no significant differences between the two groups with respect to the number of retrieved oocytes, the fertilization rate, the number of embryos frozen, and the number of embryos transferred. There were no correlations between ATA (TPOA and TGA) titers and the fertilization rate. The clinical pregnancy rate per cycle was significantly lower in the study group, with 26.3% (10/38), compared with 39.3% (35/89) in the control group. The biochemical pregnancy rate per cycle and the miscarriage rate were significantly higher in the study group, 18.4% (7/38) and 40.0% (4/10), respectively, compared with 5.6% (5/89) and 11.4% (4/35), respectively, in the control group. In the study group, both TPOA and TGA titers were significantly higher in the biochemical pregnancy group than in the clinical pregnancy group or the nonpregnancy group. In 10 women with ATAs who achieved pregnancy after IVF-ET, both TPOA and TGA titers were significantly higher in the miscarriage group than in the ongoing pregnancy/delivery group.

CONCLUSION

ATAs in euthyroid women with tubal or unexplained infertility have an association with a poor pregnancy outcome after IVF-ET treatment.

Characterization of Mas-7-induced pore formation in SK-N-BE(2)C human neuroblastoma cells

Mastoparan, a peptide toxin from wasp venome, mimics receptors by stimulating the GTPase activity of guanine nucleotide binding proteins and the G-protein-coupled phospholipase C (PLC). By using Mas-7, the active analog of mastoparan, we showed that it makes pores in the plasma membrane. Treatment with Mas-7 but not Mas-17, the inactive analog, produced a concentration-dependent rise in intracellular Ca2+ concentration ([Ca2+]i) and facilitated the uptake of ethidium bromide (EtBr) (314 Da) to a sustained level during the stimulation. In addition, Mas-7 triggered the influx of lucifer yellow (457 Da), while it did not induce the influx of fura-2 (831 Da) and Evans blue (961 Da). However, the Mas-7-induced permeability was selectively prevented by the addition of La3+, Ni2+, and Co2+, but not Cd2+. This blocking activity was concentration-dependent. While the stimulatory effect of Mas-7 on PLC activity was dependent on extracellular Ca2+, the pore forming activity of Mas-7 was not effected by removal of extracellular Ca2+. These results, therefore, suggest that the mastoparan's action in pore formation is independent from its action in PLC stimulation and is negatively effected by inorganic cations.

Stimulation of human DBH gene expression by prostaglandin E2 in human neuroblastoma SK-N-BE(2)C cells

Prostaglandin E2 (PGE2) enhances transcription of the human dopamine beta-hydroxylase (DBH) gene in human neuroblastoma SK-N-BE(2)C cells. To identify a PGE2-responsive cis-acting element in the human DBH gene, serial deletion constructs of the human DBH 5'-upstream region fused to the chloramphenicol acetyltransferase (CAT) reporter gene were transiently transfected into SK-N-BE(2)C cells. Treatment of the transformed cells with PGE2 increased CAT expression two- to threefold in all constructs except where the promoter region was shortened beyond position -114 bp. There are several cis-regulatory elements in the region between -262 and -114 bp from the transcription initiation site that include a cyclic AMP response element (CRE) and a putative AP1 sequence. We presupposed that the CRE and AP1 might be candidates for PGE2 stimulation, and therefore, used site-directed mutagenesis to change the CRE and AP1 motives and test which of the two elements mediated the transcriptional enhancement. Only a specific mutation within the CRE sequence abolished the PGE2 effect. In addition, cotransfection with an expression vector expressing PKA inhibitor resulted in the specific blockage of the PGE2 effect on DBH gene expression. Northern blot analysis revealed that the increase in DBH gene transcription caused by PGE2 results in elevated DBH mRNA levels. Gel-retardation and competition assays confirmed that the binding of nuclear factors to the CRE site is sequence specific. Our data, therefore, indicate that PGE2 enhances the transcription of the human DBH gene. The effect is mediated by the CRE motif through activation of PKA.

A protein kinase C-activating phorbol ester enhances transcription of the human DBH gene through a cyclic AMP response element in SK-N-BE(2)C cells

Protein kinase C (PKC) activation after treatment of human neuroblastoma SK-N-BE(2)C cells with phorbol 12-myristate 13-acetate (PMA) was found to enhance transcription of the human dopamine beta-hydroxylase (DBH) in those cells. To identify which cis-acting element is responsive to the PMA treatment during DBH gene expression, we employed transient transfection assays with serially deleted constructs of the human DBH gene's 5' upstream region fused to the chloramphenicol acetyltransferase (CAT) gene. Treatment of transfected cells with PMA resulted in an approximate threefold increase in CAT expression for all deletion constructs ranging from -978 bp to -262 bp, while the enhancement did not occur with a construct shortened to -114 bp. The region between -262 and -114 bp from the initiation site of transcription contains several cis-regulatory elements including a cyclic AMP response element (CRE) and putative AP1 and YY1 sequences. Site-directed mutagenesis of those cis-acting elements were performed to identify which of the elements mediated the PMA-induced transcriptional enhancement. Substitution of bases in the putative AP1 site containing in part a putative YY1 sequence did not effect the PMA inducibility. However, specific mutations in the CRE sequence abolished the PMA-inducible effect. Changing the CRE sequence into an authentic AP1 sequence (TGACGTCC --> TGACTCA) did not affect the PMA inducibility, suggesting that AP1 factors might interact with the new AP1 site upon PKC activation. A specific PKC inhibitor, GF109203X, completely inhibited the stimulatory effect of PMA on the expression of the human DBH gene. PMA induced an increase in the DBH mRNA level as detected by Northern blot analysis. Gel retardation showed that the binding of nuclear factors to CRE, putative YY1, and AP1 was sequence specific. Our data suggest that the enhancement of the human DBH gene expression by PMA treatment is mediated by the CRE motif in the 5' upstream region of the gene, and occurs via a PKC-dependent pathway.

The immunotherapy during in vitro fertilization and embryo transfer cycles in infertile patients with endometriosis

OBJECTIVE

To investigate if the immunotherapy with corticosteroids would improve the pregnancy rate in infertile patients with endometriosis who undergo in vitro fertilization and embryo transfer (IVF-ET).

METHODS

Forty-two infertile patients with endometriosis plus tubal factor and 87 pure tubal infertility patients who underwent IVF-ET in our unit were allocated randomly to the corticosteroid treatment group and the control group.

RESULTS

The prevalence of autoantibodies (antinuclear antibody, lupus anticoagulant, anticardiolipin antibody, rheumatoid factor) was elevated significantly in patients with endometriosis plus tubal factor compared with pure tubal infertility patients (38.1% vs 2.3%). Twenty-one patients with endometriosis plus tubal factor underwent 54 cycles of IVF-ET, receiving corticosteroids. Forty-three patients with pure tubal factor underwent 81 cycles of IVF-ET, receiving corticosteroids. Twenty-one patients with endometriosis plus tubal factor who underwent 57 cycles of IVF-ET and 44 patients with pure tubal factor who underwent 84 cycles of IVF-ET served as controls, not receiving corticosteroids. In patients with endometriosis plus tubal factor, there was a significantly higher clinical pregnancy rate per cycle in the treatment group, with 42.6% (23/54) compared with 22.8% (13/57) in the control group but no differences between 2 groups in spontaneous abortion rate (21.7% vs 15.4%) and multiple pregnancy rate (17.4% vs 15.4%). In patients with pure tubal infertility, there were no significant differences between the treatment group and control group in clinical pregnancy rate (40.7% vs 34.5%), spontaneous abortion rate (12.1% vs 10.3%) or multiple pregnancy rate (18.2% vs 10.3%). In the endometriosis plus tubal infertility group with autoantibodies, the clinical pregnancy rate per cycle was significantly higher in the treatment group at 40.9% compared with 14.8% in the control group. In endometriosis plus tubal infertility group without autoantibodies, there was no significant difference between 2 groups with respect to the clinical pregnancy rate per cycle (43.8% vs 30.0%).

CONCLUSIONS

This study suggests that immunotherapy with corticosteroids could improve the clinical pregnancy rate in endometriosis patients undergoing IVF-ET and may be more effective in patients with positive autoantibodies.

Stimulation of the A2A adenosine receptor increases expression of the tyrosine hydroxylase gene

PC12 cells are known to express A2A adenosine receptors that are linked to adenylyl cyclase. We investigated the role played by A2A adenosine receptors in the expression of the rat tyrosine hydroxylase (TH) gene in PC12 cells. The A2A selective adenosine receptor agonist 2-(p-2-carboxyethyl)phenylethylamino)-5'-N-ethylcarboxyamidoade nosine (CGS21680) caused TH mRNA levels to increase to more than twice the level of the untreated control. Transient transfection analysis demonstrated that the transcription of the TH gene was markedly enhanced upon treatment with CGS21680. The adenosine receptor-mediated TH gene expression was confirmed by the inhibitory effects that adenosine receptor antagonists had on the CGS21680 response. Mutational analysis of the 5' upstream region of the TH gene revealed that the cAMP response element (CRE) at -45 to -38 bp was responsible for the CGS21680 effect. Gel mobility shift assays revealed that six CRE-specific DNA-protein complexes were formed, and the amounts of three of them were significantly increased by treatment with CGS21680. Co-transfection with an expression vector containing protein kinase A (PKA) inhibitor markedly decreased the CGS21680 effect. The results suggest that stimulation of the A2A adenosine receptor leads to an elevated expression of the TH gene by changing the binding pattern of DNA binding proteins that interact with CRE through activation of protein kinase A.