To develop a gentamicin-loaded wound dressing, cross-linked hydrogel films were prepared with polyvinyl alcohol (PVA) and dextran using the freezing–thawing method. Their gel properties such as gel fraction, swelling, water vapor transmission test, morphology, tensile strength, and thermal property were investigated. In vitro protein adsorption test, in vivo wound healing test, and histopathology were performed. Dextran decreased the gel fraction, maximum strength, and thermal stability of hydrogels. However, it increased the swelling ability, water vapor transmission rate, elasticity, porosity, and protein adsorption. The drug gave a little positive effect on the gel properties of hydrogels. The gentamicin-loaded wound dressing composed of 2.5% PVA, 1.13% dextran, and 0.1% drug was more swellable, flexible, and elastic than that with only PVA because of its cross-linking interaction with PVA. In particular, it could provide an adequate level of moisture and build up the exudates on the wound area. From the in vivo wound healing and histological results, this gentamicin-loaded wound dressing enhanced the healing effect more compared to conventional product because of the potential healing effect of gentamicin. Thus, this gentamicin-loaded wound dressing would be used as a potential wound dressing with excellent forming and improved healing effect in wound care.
dextran; gentamicin; histological examination; wound dressing; wound healing effect
Intracranial extraskeletal myxoid chondrosarcoma is extremely rare, with only seven patients previously reported. We present a case report of a 21-year-old woman admitted for weakness in her right extremities and symptoms of increased intracranial pressure. Magnetic resonance imaging (MRI) revealed hydrocephalus and a well-enhanced large mass around her left thalamus. A left parietal craniotomy and a cortisectomy at the superior parietal lobule were performed. Total surgical resection was also performed, and pathology results confirmed an extraskeletal myxoid chondrosarcoma. Postoperative MRI showed no residual tumor, and the patient underwent radiotherapy. After six months of radiotherapy, the patient's headache and weakness had improved to grade IV. This malignant tumor showed high rates of recurrence in previous reports. We here report another occurrence of this highly malignant and rare tumor in a patient treated using total surgical excision and adjuvant radiotherapy.
Brain neoplasms; Chondrosarcoma; Choroid plexus
Repeated administration of psychostimulants such as cocaine leads to the development of behavioral sensitization. Extracellular signal-Regulated Kinase (ERK), an enzyme important for long-term neuronal plasticity, has been implicated in such effects of these drugs. Although the nucleus accumbens (NAcc) is the site mediating the expression of behavioral sensitization by drugs of abuse, the precise role of ERK activation in this site has not been determined. In this study we demonstrate that blockade of ERK phosphorylation in the NAcc by a single bilateral microinjections of PD98059 (0.5 or 2.0µ g/side), or U0126 (0.1 or 1.0µg/side), into this site dose-dependently inhibited the expression of cocaine-induced behavioral sensitization when measured at day 7 following 6 consecutive daily cocaine injections (15 mg/kg, i.p.). Acute microinjection of either vehicle or PD98059 alone produced no different locomotor activity compared to saline control. Further, microinjection of PD98059 (2.0µ g/side) in the NAcc specifically lowered cocaine-induced increase of ERK phosphorylation levels in this site, while unaffecting p-38 protein levels. These results indicate that ERK activation in the NAcc is necessary for the expression of cocaine-induced behavioral sensitization, and further suggest that repeated cocaine evokes neuronal plasticity involving ERK pathway in this site leading to long-lasting behavioral changes.
Cocaine; Behavioral sensitization; PD98059; U0126; Nucleus accumbens
Papillary thyroid cancer with level VII (anterior superior mediastinal lymph nodes) lymph node metastasis belongs to Stage IV a according to the Americal Joint Committee on Cancer cancer staging. The aim of our study was to identify clinicopathologic factors that are related to level VII cervical lymph node metastasis and to suggest recommendations for level VII dissection.
We reviewed 195 patients with papillary thyroid carcinoma who had their initial operation containing level VII dissection from April 2006 to June 2007. Level VII dissection involved lymph nodes in the anterior superior mediastinum and tracheoesophageal grooves, extending from the suprasternal notch to the innominate artery. Clinicophathologic factors, such as gender, age and lateral neck metastasis, related to Level VII metastasis were analyzed by tumor size, multifocality of tumor, extrathyroidal extension and lymphovascular invasion.
Nine (4.6%) of 195 patients with papillary thyroid carcinoma had level VII metastasis. Clinicopathologic factors that were related to level VII metastasis included lateral neck metastasis (P < 0.01), tumor size (P < 0.01) and lymphovascular invasion (P < 0.05).
If preoperatively, the tumor size is over 1.5 cm, or there is lateral neck metastasis, level VII dissection must be considered. If there is lymphovascular invasion pathologic findings postoperatively, special attention should be paid for detection of level VII recurrence.
Level VII dissection; Papillary thyroid carcinoma
Ectopic thyroid glands generally occur in the midline as a result of abnormal median migration, and their presence lateral to the midline is rare. We present one case of an ectopic thyroid gland masquerading as a lateral neck metastasis of a papillary thyroid carcinoma (PTC). In this case of a 54-yr-old woman with left PTC, we suspected left lateral neck metastasis on preoperative neck computed tomography. The patient underwent total thyroidectomy, central compartment neck dissection, and left modified radical neck dissection (MRND). The patient was diagnosed as having an accessory thyroid gland on the lateral neck on the final pathologic report. Surgeons should be aware of the existence of an ectopic thyroid gland in unusual locations.
Ectopic Thyroid; Carcinoma, Papillary
Many cases of RET proto-oncogene mutations of hereditary medullary thyroid carcinoma (MTC) have been reported in Korea. However, MTC with V804M RET proto-oncogene germline mutations have not been reported in Korea. A 33-yr-old man was diagnosed with a 0.7-cm sized thyroid nodule. Laboratory testing revealed serum calcitonin was elevated. The patient underwent total thyroidectomy with central compartment neck dissection for the thyroid tumor. RET gene analysis was performed in both the index patient and his family. There were no V804M RET mutation and abnormal laboratory findings within his family except the index patient. Therefore, this patient was a de novo V804M RET germline mutation.
Medullary Thyroid Carcinoma; RET Proto-oncogene; V804M RET Germline Mutation
Little is known about the transcriptional regulation of tumor angiogenesis, and tumor ECs (tECs) remain poorly characterized. Here, we studied the expression pattern of the transcription factor Sox17 in the vasculature of murine and human tumors and investigated the function of Sox17 during tumor angiogenesis using Sox17 genetic mouse models. Sox17 was specifically expressed in tECs in a heterogeneous pattern; in particular, strong Sox17 expression distinguished tECs with high VEGFR2 expression. Whereas overexpression of Sox17 in tECs promoted tumor angiogenesis and vascular abnormalities, Sox17 deletion in tECs reduced tumor angiogenesis and normalized tumor vessels, inhibiting tumor growth. Tumor vessel normalization by Sox17 deletion was long lasting, improved anticancer drug delivery into tumors, and inhibited tumor metastasis. Sox17 promoted endothelial sprouting behavior and upregulated VEGFR2 expression in a cell-intrinsic manner. Moreover, Sox17 increased the percentage of tumor-associated CD11b+Gr-1+ myeloid cells within tumors. The vascular effects of Sox17 persisted throughout tumor growth. Interestingly, Sox17 expression specific to tECs was also observed in highly vascularized human glioblastoma samples. Our findings establish Sox17 as a key regulator of tumor angiogenesis and tumor progression.
Primary cardiac lymphoma (PCL) is a rare disorder, but the incidence is increasing and its clinical manifestations are various. We report a case of PCL, which mimics an acute coronary and aortic syndrome. A 51 year-old female was presented with chest pain radiating to the back. Her initial electrocardiogram revealed T wave inversion in the leads of V 5-6, II, III and aVF. Additionally, cardiac troponin-T was slightly elevated. Chest radiography showed marked mediastinal widening. Computed tomography scan showed a huge pericardial mass. The histopathologic findings of the mass were compatible with diffuse large B cell lymphoma. She died of refractory ventricular tachycardia, probably, due to an extensive infiltration of PCL to the myocardium.
Cardiac tumor; Chest pain; Acute coronary syndrome
Recently, lymph node metastasis (LNM) has been regarded as an important factor influencing loco-regional recurrence and survival rate in papillary thyroid cancer (PTC) patients. The aims of this study were to investigate the detection rate and metastasis rate of the Delphian lymph node (DLN) and clinical patterns related to regional LNM, and to examine how DLN metastasis affects PTC treatment.
We reviewed the medical records of 413 patients with pathologically confirmed PTC from among 452 patients who underwent thyroid surgery between January 2010 and October 2010 in the Department of Endocrine Surgery at Kosin University Gospel Hospital in Busan, South Korea.
Multivariate analyses revealed a significantly higher proportion of cases with lymphovascular invasion (56.6% vs. 12.5%, P <0.001), central neck node metastasis (88.6% vs. 34.5%, P <0.001) and lateral neck node metastasis (47.2% vs. 10.2%, P <0.005) among cases with DLN metastasis compared to those without. The negative predictive value (NPV) of DLN metastasis with regard to the presence of contralateral central LNM for cases with a tumor size 1 cm or smaller than 1 cm was found to be 93.3% (127/136).
When DLN metastasis is not detected in papillary thyroid microcarcinomas (PTMC), thyroid lobectomy on the affected side and ipsilateral central neck lymph node dissection should be sufficient. In addition, even in cases where lateral neck LNM is not detected on preoperative examination, if DLN metastasis is detected postoperatively, more careful attention should be paid to the lateral neck nodes during follow-up.
Delphian lymph node; Papillary thyroid cancer; Central neck lymph node
This study was performed to determine the safety and outcome of concurrent chemoradiotherapy (CCRT) and adjuvant chemotherapy with temozolomide for Korean patients with a newly diagnosed glioblastoma.
Patients were recruited from four institutions between 2004 and 2007. The patients received fractionated focal irradiation in daily fractions of 2 Gy given 5 days per week for 6 weeks and daily temozolomide, followed by 6 cycles of adjuvant temozolomide. The primary endpoint was overall survival (OS) and the secondary endpoints were progression-free survival (PFS), response, and safety.
A total of 103 patients were enrolled in this study. Ninety-six patients (93%) completed the CCRT and 54 patients (52%) received 6 cycles of adjuvant temozolomide. The response rate was 73% (53/73) and the tumor control rate was 92% (67/73). Of the 96 patients who completed the CCRT, the median OS was 18.0 months and the 1- and 2-year OS rates were 74 and 38%, respectively. The median PFS was 10.0 months and the 1- and 2-year PFS rates were 33 and 16%, respectively. The only significant prognostic factor of survival was the extent of surgical resection (p<0.05). CCRT resulted in grade 3 or 4 hematologic toxic effects in 8% of patients. No opportunistic infections were noted.
This study is the first prospective multi-institutional report of CCRT and adjuvant chemotherapy with temozolomide for patients with a newly diagnosed glioblastoma in Korea. The current protocol may prolong the survival of Korean patients with a glioblastoma and may be tolerable in terms of toxicity.
Temozolomide; Chemoradiotherapy; Glioblastoma; Korea
Neurofibromatosis type 1 is a common heritable neurocutaneous disorder. Neurofibromatosis type 1 may be associated with tumors of the central nervous system and pheochromocytoma. However, papillary thyroid carcinoma associated with neurofibromatosis type 1 is very rare. We present what is, to the best of our knowledge, the first case of papillary thyroid carcinoma to be detected incidentally by ultrasonography in a patient with neurofibromatosis type 1.
A 63-year-old South Korean man with neurofibromatosis type 1 presented to our study hospital because of thyroid nodules detected incidentally by ultrasonography. Papillary thyroid carcinoma was diagnosed by ultrasonography-guided fine-needle aspiration, and then a total thyroidectomy with central compartment neck dissection was performed. The B isoform of the RafV600E mutation was identified by multiplex real-time polymerase chain reaction assay.
Papillary thyroid carcinoma associated with neurofibromatosis type 1 is very rare. However, it is speculated that papillary thyroid carcinoma is more likely to be detected in patients with neurofibromatosis type 1 if screening by ultrasonography is performed for them.
Aberrant activation of Wnt/β-catenin signaling, resulting in the expression of Wnt regulated oncogenes, is recognized as a critical factor in the etiology of colorectal cancer. Occupancy of β-catenin at promoters of Wnt target genes drives transcription, but the mechanism of β-catenin action remains poorly understood. Here, we show that CARM1 (coactivator associated protein arginine methyltransferase 1) interacts with β-catenin and positively modulates β-catenin-mediated gene expression. In colorectal cancer cells with constitutively high Wnt/β-catenin activity, depletion of CARM1 inhibits expression of endogenous Wnt/β-catenin target genes and suppresses clonal survival and anchorage-independent growth. We also identified a colorectal cancer cell line (RKO) with a low basal level of β-catenin, which is dramatically elevated by treatment with Wnt3a. Wnt3a also increased expression of a subset of endogenous Wnt target genes, and CARM1 was required for the Wnt-induced expression of these target genes and the accompanying dimethylation of arginine 17 of histone H3. Depletion of β-catenin from RKO cells diminished the Wnt-induced occupancy of CARM1 on a Wnt target gene, indicating that CARM1 is recruited to Wnt target genes through its interaction with β-catenin and contributes to transcriptional activation by mediating events (including histone H3 methylation) which are downstream from the actions of β-catenin. Therefore, CARM1 is an important positive modulator of Wnt/β-catenin transcription and neoplastic transformation, and may thereby represent a novel target for therapeutic intervention in cancers involving aberrantly activated Wnt/β-catenin signaling.
CARM1; Wnt/β-catenin; coactivators; transcriptional regulation; colorectal cancers
Primary central nervous system lymphoma (PCNSL) rarely relapses in extracranial sites, and no specialized guidelines for follow-up evaluation have been proposed.
We analyzed 65 patients with newly diagnosed PNCSL to evaluate the pattern of relapse and prognostic factors.
Of the 65 patients analyzed, 55 had only parenchymal brain disease, and 10 had both intracranial and extracranial lesions. As a first-line treatment, 29 patients received chemotherapy only (CTx), 13 received chemotherapy followed by whole brain radiotherapy (CTx-WBRT), 18 received chemotherapy followed by autologous stem cell transplantation (CTx-ASCT), 2 received palliative WBRT, and 3 received best supportive care. The overall response rate to the initial treatment was 75.8%, with specific response rates of 62.1% to CTx, 84.6% to CTx-WBRT, and 100% to CTx-ASCT. The complete response (CR) rate was higher with CTx-ASCT than in the absence of ASCT (77.8% vs. 43.2%; P=0.025). After a median follow-up of 18.8 months, the median failure-free survival (FFS) and overall survival (OS) were 13.0 and 36.1 months, respectively. No systemic relapse without a CNS lesion was noted. Multivariate analysis showed that ASCT was predictive of better FFS but not of OS. Age and the Memorial-Sloan Kettering Cancer Center prognostic score were predictive of survival.
We observed no systemic relapse without a CNS lesion, suggesting that regular systematic evaluation of extracranial sites may not always be necessary. Age was prognostic of survival irrespective of treatment scheme. ASCT may improve CR rate and FFS.
Primary CNS lymphoma; Relapse; Prognostic factor
Amphetamine, a synthetic psychostimulant, is transported by the dopamine transporter (DAT) to the cytosol and increases the exchange of extracellular amphetamine by intracellular dopamine. Recently, we reported that the phosphorylation levels of ezrin-radixin-moesin (ERM) proteins are regulated by psychostimulant drugs in the nucleus accumbens, a brain area important for drug addiction. However, the significance of ERM proteins phosphorylation in response to drugs of abuse has not been fully investigated. In this study, using PC12 cells as an in vitro cell model, we showed that amphetamine increases ERM proteins phosphorylation and protein kinase C (PKC) β inhibitor, but not extracellular signal-regulated kinase (ERK) or phosphatidylinositol 3-kinases (PI3K) inhibitors, abolished this effect. Further, we observed that DAT inhibitor suppressed amphetamine-induced ERM proteins phosphorylation in PC12 cells. These results suggest that PKCβ-induced DAT regulation may be involved in amphetmaine-induced ERM proteins phosphorylation.
Amphetamine; ERM proteins (ezrin, radixin, moesin); PKCβ; PC12 cells; Dopamine transporter
Estrogen receptor α (ERα) plays critical roles in development and progression of breast cancer. Because ERα activity is strictly dependent upon the interaction with coregulators, coregulators are also believed to contribute to breast tumorigenesis. Cell Cycle and Apoptosis Regulator 1 (CCAR1) is an important co-activator for estrogen-induced gene expression and estrogen-dependent growth of breast cancer cells. Here, we identified Deleted in Breast Cancer 1 (DBC1) as a CCAR1 binding protein. DBC1 was recently shown to function as a negative regulator of the NAD-dependent protein deacetylase SIRT1. DBC1 associates directly with ERα and cooperates synergistically with CCAR1 to enhance ERα function. DBC1 is required for estrogen-induced expression of a subset of ERα target genes as well as breast cancer cell proliferation and for estrogen-induced recruitment of ERα to the target promoters in a gene-specific manner. The mechanism of DBC1 action involves inhibition of SIRT1 interaction with ERα and of SIRT1-mediated deacetylation of ERα. SIRT1 also represses the co-activator synergy between DBC1 and CCAR1 by binding to DBC1 and disrupting its interaction with CCAR1. Our results indicate that DBC1 and SIRT1 play reciprocal roles as major regulators of ERα activity, by regulating DNA binding by ERα and by regulating co-activator synergy.
Background and Objectives
Aspiration thrombectomy (AT) during primary percutaneous coronary intervention (PCI) is an effective adjunctive therapy for ST-segment elevation myocardial infarction (STEMI). An elevated neutrophil count in STEMI is associated with microvascular dysfunction and adverse outcomes. We evaluated whether AT can improve microvascular dysfunction in patients with STEMI and an elevated neutrophil count.
Subjects and Methods
Seventy patients with STEMI undergoing primary PCI from August 2007 to February 2009 in our institution were classified by tertiles of neutrophil count on admission (<5,300/mm3, 5,300-7,600/mm3, and >7,600/mm3). The angiographic outcome was post-procedural thrombolysis in myocardial infarction (TIMI) flow grade. Microvascular dysfunction was assessed by TIMI myocardial perfusion (TMP) grade and ST-segment resolution on electrocardiography 90 minutes after PCI. The clinical outcome was major adverse cardiac event (MACE), defined as cardiac death, re-infarction, and target lesion revascularization at 9 months.
There were no significant differences in the clinical characteristics and pre- and post-procedural TIMI flow grades between the neutrophil tertiles. As the neutrophil count increased, a lower tendency toward TMP grade 3 (83% vs. 52% vs. 54%, p=0.06) and more persistent residual ST-segment elevation (>4 mm: 13% vs. 26% vs. 58%, p=0.005) was observed. The 9-month MACE rate was similar between the groups. On subgroup analysis of AT patients (n=52) classified by neutrophil tertiles, the same tendency toward less frequent TMP grade 3 (77% vs. 56% vs. 47%, p=0.06) and persistent residual ST-segment elevation (>4 mm: 12% vs. 28% vs. 53%, p=0.05) was observed as neutrophil count increased.
A higher neutrophil count at presentation in STEMI is associated with more severe microvascular dysfunction after primary PCI, which is not improved with AT.
Myocardial infarction; Neutrophils
Primary cardiac lymphomas (PCL) are extremely rare. Clinical manifestations may be variable and are attributed to location. Here, we report on a case of PCL presenting with atrioventricular (AV) block. A 55 year-old male had experienced chest discomfort with unexplained dyspnea and night sweating. His initial electrocardiogram (ECG) revealed a first degree AV block. Along with worsening chest discomfort and dyspnea, his ECG changed to show second degree AV block (Mobitz type I). Computed tomography (CT) scan showed a cardiac mass (about 7 cm) and biopsy was performed. Pathologic finding confirmed diffuse large B-cell lymphoma. The patient was treated with multi-drug combination chemotherapy (R-CHOP: Rituximab, cyclophoshamide, anthracycline, vincristine, and prednisone). After treatment, ECG changed to show normal sinus rhythm with complete remission on follow-up CT scan.
Lymphoma, Large B-cell, Diffuse; Cardiac tumor; Atrioventricular block
Primary cardiac angiosarcoma is a very rare disease with a poor prognosis. We report a case of a patient with a primary cardiac angiosarcoma who presented with cardiac tamponade; the angiosarcoma was successfully resected surgically.
Cardiac tumor; Angiosarcoma; Hemopericardium
The non-essential VTS1 gene of Saccharomyces cerevisiae is highly conserved in eukaryotes and encodes a sequence- and structure-specific RNA-binding protein. The Vts1 protein has been implicated in post-transcriptional regulation of a specific set of mRNAs that contains its-binding site at their 3′-untranslated region. In this study, we identified VTS1 as a multi-copy suppressor of dna2-K1080E, a lethal mutant allele of DNA2 that lacks DNA helicase activity. The suppression was allele-specific, since overexpression of Vts1 did not suppress the temperature-dependent growth defects of dna2Δ405N devoid of the N-terminal 405-amino-acid residues. Purified recombinant Vts1 stimulated the endonuclease activity of wild-type Dna2, but not the endonuclease activity of Dna2Δ405N, indicating that the activation requires the N-terminal domain of Dna2. Stimulation of Dna2 endonuclease activity by Vts1 appeared to be the direct cause of suppression, since the multi-copy expression of Dna2-K1080E suppressed the lethality observed with its single-copy expression. We found that vts1Δ dna2Δ405N and vts1Δdna2-7 double mutant cells displayed synergistic growth defects, in support of a functional interaction between two genes. Our results provide both in vivo and in vitro evidence that Vts1 is involved in lagging strand synthesis by modulating the Dna2 endonuclease activity that plays an essential role in Okazaki fragment processing.
Although cabergoline is effective in the treatment of micro- and macro-prolactinoma, little is known about its efficacy in the treatment of invasive giant prolactinoma. We investigated the efficacy and safety of cabergoline in 10 male patients with invasive giant prolactinoma. Before treatment, mean serum prolactin level was 11,426 ng/mL (range, 1,450-33,200 ng/mL) and mean maximum tumor diameter was 51 mm (range, 40-77 mm). Three months after initiation of cabergoline treatment, serum prolactin concentrations decreased more than 97% in 9 patients; at last follow-up (mean treatment duration, 19 months), the mean decrease in serum prolactin concentrations was 98%, with 5 patients having normal serum prolactin levels. At first MRI follow-up (3-12 months after initiation of cabergoline), the mean reduction in tumor size was 85±4% (range, 57-98%). Cabergoline treatment for more than 12 months caused a greater reduction in tumor size compared to the treatment for less than 12 months (97±1% vs. 78±7%, P<0.05). These findings indicate that cabergoline treatment led to a significant and rapid reduction in serum prolactin concentrations and tumor size in patients with giant prolactinoma. Therefore, cabergoline represents an effective and well-tolerated treatment for invasive giant prolactinoma.
Invasive Giant Prolactinoma; Cabergoline; Male; Prolactin; Tumor Size
DNA-bound transcription factors recruit many coactivator proteins to remodel chromatin and activate transcription. The Mediator complex is believed to recruit RNA polymerase II to most protein-encoding genes. It is generally assumed that interaction of Mediator subunits with DNA-binding transcription factors is responsible for Mediator recruitment to promoters. However, we report here that Mediator recruitment by nuclear receptors (NR) requires a new coactivator protein, CCAR1 (cell cycle and apoptosis regulator 1). CCAR1 associates with components of the Mediator and p160 coactivator complexes and is recruited to endogenous NR target genes in response to the appropriate hormone. Reduction of endogenous CCAR1 levels inhibited hormone-induced expression of endogenous NR target genes, hormone-induced recruitment of Mediator components and RNA polymerase II to target gene promoters, and estrogen-dependent growth of breast cancer cells. Thus, CCAR1 regulates expression of key proliferation inducing genes. CCAR1 also functions as a p53 coactivator, suggesting a broader role in transcriptional regulation.
The Saccharomyces cerevisiae Srs2 UvrD DNA helicase controls genome integrity by preventing unscheduled recombination events. While Srs2 orthologues have been identified in prokaryotic and lower eukaryotic organisms, human orthologues of Srs2 have not been described so far. We found that the human F-box DNA helicase hFBH1 suppresses specific recombination defects of S. cerevisiae srs2 mutants, consistent with the finding that the helicase domain of hFBH1 is highly conserved with that of Srs2. Surprisingly, hFBH1 in the absence of SRS2 also suppresses the DNA damage sensitivity caused by inactivation of postreplication repair-dependent functions leading to PCNA ubiquitylation. The F-box domain of hFBH1, which is not present in Srs2, is crucial for hFBH1 functions in substituting for Srs2 and postreplication repair factors. Furthermore, our findings indicate that an intact F-box domain, acting as an SCF ubiquitin ligase, is required for the DNA damage-induced degradation of hFBH1 itself. Overall, our findings suggest that the hFBH1 helicase is a functional human orthologue of budding yeast Srs2 that also possesses self-regulation properties necessary to execute its recombination functions.
The coiled-coil coactivator (CoCoA) is involved in transcriptional activation of target genes by nuclear receptors and the xenobiotic aryl hydrocarbon receptor, as well as target genes of the Wnt signaling pathway, which is mediated by the lymphocyte enhancer factor (LEF)/T cell factor transcription factors and the coactivator β-catenin. The recruitment of CoCoA by nuclear receptors is accomplished by the interaction of the central coiled-coiled domain of CoCoA with p160 coactivators; the C-terminal activation domain (AD) of CoCoA is used for downstream signaling, while the function of the N-terminal region was undefined. Here we report that the N-terminus of CoCoA contains another AD, which is necessary and sufficient for synergistic activation of LEF1-mediated transcription by CoCoA and β-catenin. The N-terminal AD contains a p300 binding motif, which is important for synergistic cooperation of CoCoA and p300 as coactivators for LEF1 and β-catenin. p300 contributes to the function of the CoCoA N-terminal AD primarily through its histone acetyltransferase activity. Moreover, in cultured cells endogenous p300 is recruited to the promoter of an integrated reporter gene by the N-terminus of CoCoA. Thus, the coactivator function of CoCoA for nuclear receptors and LEF1/β-catenin involves differential utilization of two different CoCoA ADs.
coactivator; CoCoA; β-catenin; p300; LEF1
The aryl hydrocarbon receptor (AHR), a member of the basic helix-loop-helix/Per-Arnt-Sim (bHLH-PAS) gene family, binds a variety of polycyclic aromatic hydrocarbons and mediates their toxic effects. GAC63 has been shown to act as a coactivator in nuclear receptor (NR) mediated gene transcription. In this report, we demonstrate that GAC63 interacts with AHR through its bHLH-PAS domain. Overexpression of GAC63 greatly enhanced AHR-regulated reporter gene activity in a ligand-dependent manner in transient transfection assays. Upon ligand treatment, endogenous GAC63 was recruited to the xenobiotic response element (XRE) of the mouse CYP1A1 gene, an AHR-responsive gene. Reduction of the endogenous GAC63 level by small interfering RNA (siRNA) inhibited transcriptional activation by AHR. These findings reveal a new function of GAC63 in AHR-mediated gene transcription.
β-catenin, a pivotal component of the Wnt-signaling pathway, binds to and serves as a transcriptional coactivator for the T-Cell Factor/Lymphoid Enhancer Factor (TCF/LEF) family of transcriptional activator proteins, and also for the androgen receptor (AR), a nuclear receptor. Three components of the p160 nuclear receptor coactivator complex, including CARM1, p300/CBP, and GRIP1 (one of the p160 coactivators), bind to and cooperate with β-catenin to enhance transcriptional activation by TCF/LEF and AR. Here we report that another component of the p160 nuclear receptor coactivator complex, the coiled-coil coactivator (CoCoA), directly binds to and cooperates synergistically with β-catenin as a coactivator for AR and TCF/LEF. CoCoA uses different domains to bind GRIP1 and β-catenin, and it uses different domains to transmit the activating signal to the transcription machinery, depending on whether it is bound to GRIP1 or β-catenin. CoCoA associated specifically with the promoters of transiently transfected and endogenous target genes of TCF/LEF, and reduction of the endogenous CoCoA level decreased the ability of TCF/LEF and β-catenin to activate transcription of transient and endogenous target genes. Thus, CoCoA uses different combinations of functional domains to serve as a physiologically relevant component of the Wnt/β-catenin signaling pathway and the androgen signaling pathway.