Astrocytic water channel aquaporin-4 modulates brain plasticity in both mice and humans: a potential gliogenetic mechanism underlying language-associated learning.

The role of astrocytes in brain plasticity has not been extensively studied compared with that of neurons. Here we adopted integrative translational and reverse-translational approaches to explore the role of an astrocyte-specific major water channel in the brain, aquaporin-4 (AQP4), in brain plasticity and learning. We initially identified the most prevalent genetic variant of AQP4 (single nucleotide polymorphism of rs162008 with C or T variation, which has a minor allele frequency of 0.21) from a human database (n=60 706) and examined its functionality in modulating the expression level of AQP4 in an in vitro luciferase reporter assay. In the following experiments, AQP4 knock-down in mice not only impaired hippocampal volumetric plasticity after exposure to enriched environment but also caused loss of long-term potentiation after theta-burst stimulation. In humans, there was a cross-sectional association of rs162008 with gray matter (GM) volume variation in cortices, including the vicinity of the Perisylvian heteromodal language area (Sample 1, n=650). GM volume variation in these brain regions was positively associated with the semantic verbal fluency. In a prospective follow-up study (Sample 2, n=45), the effects of an intensive 5-week foreign language (English) learning experience on regional GM volume increase were modulated by this AQP4 variant, which was also associated with verbal learning capacity change. We then delineated in mice mechanisms that included AQP4-dependent transient astrocytic volume changes and astrocytic structural elaboration. We believe our study provides the first integrative evidence for a gliogenetic basis that involves AQP4, underlying language-associated brain plasticity.

Identifying the potential long-term survivors among breast cancer patients with distant metastasis.

BACKGROUND: We aimed to develop a prediction model to identify long-term survivors after developing distant metastasis from breast cancer. PATIENTS AND METHODS: From the institution's database, we collected data of 547 patients who developed distant metastasis during their follow-ups. We developed a model that predicts the post-metastasis overall survival (PMOS) based on the clinicopathologic factors of the primary tumors and the characteristics of the distant metastasis. For validation, the survival data of 254 patients from four independent institutions were used. RESULTS: The median duration of the PMOS was 31.0 months. The characteristics of the initial primary tumor, such as tumor stage, hormone receptor status, and Ki-67 expression level, and the characteristics of the distant metastasis presentation including the duration of disease-free interval, the site of metastasis, and the presence of metastasis-related symptoms were independent prognostic factors determining the PMOS. The association between tumor stage and the PMOS was only seen in tumors with early relapses. The PMOS score, which was developed based on the above six factors, successfully identified patients with superior survival after metastasis. The median PMOS for patients with a PMOS score of <2 and for patients with a PMOS score of >5 were 71.0 and 12 months, respectively. The clinical significance of the PMOS score was further validated using independent multicenter datasets. CONCLUSIONS: We have developed a novel prediction model that can classify breast cancer patients with distant metastasis according to their survival after metastasis. Our model can be a valuable tool to identify long-term survivors who can be potential candidates for more intensive multidisciplinary approaches. Furthermore, our model can provide a more reliable survival information for both physicians and patients during their informed decision-making process.

Steroid plus antiviral treatment for Bell's palsy.

OBJECTIVES: The effectiveness of antiviral agents for the treatment of Bell's palsy is uncertain. We evaluated whether a steroid with an antiviral agent (S + A group) provided better recovery outcomes than a steroid alone (S group) in patients with Bell's palsy. SUBJECTS AND DESIGN: A total of 1342 patients diagnosed with Bell's palsy who visited the Kyung Hee Medical Center in Seoul, Korea, from 2002 to 2012 were included in this study. Patients in the S + A group were treated with prednisolone and antiviral agents (n = 569) and those in the S group with prednisolone alone (n = 773). Outcomes were measured using the House-Brackmann (HB) scale according to age, initial disease severity, electroneurography (ENoG) findings and underlying comorbidities. RESULTS: The rate of recovery (HB grades I and II) with initially severe Bell's palsy (HB grades V and VI) was higher in the S + A than in the S group (P = 0.001). However, the rates of recovery were similar with initially moderate palsy (HB grades II-IV) (P = 0.502). In patients classified according to age and ENoG-determined severity of palsy, the overall recovery rate was higher in the S + A than in the S group, but the differences were not statistically significant (P > 0.05 for both). The recovery rate without diabetes mellitus (DM) and hypertension (HTN) was higher in the S + A group than in the S group (P = 0.031). But in the patients with HTN and DM, the difference in recovery rates between the S + A and S groups was not statistically significant (P = 0.805). CONCLUSIONS: Treatment with a steroid plus antiviral agent resulted in significantly higher recovery rates than steroid therapy alone in patients with initially severe Bell's palsy and without either HTN or DM, and a nonsignificant trend towards higher recovery rates in all patients with Bell's palsy in this study. Antiviral agents may therefore help in the treatment of Bell's palsy.

Comparison of steroid administration methods in patients with idiopathic sudden sensorineural hearing loss: a retrospective observational study.

OBJECTIVES: To compare the recovery rates of patients with idiopathic sudden sensorineural hearing loss (ISSHL) treated with oral systemic steroids (PO) or intratympanic steroid injection (IT) or both. DESIGN: A retrospective observational study. SETTING: Tertiary referral centre. PARTICIPANTS: Eight hundred and forty-four patients diagnosed with ISSHL within 14 days of the onset of symptoms. The patients were divided into three groups by treatment modality. MAIN OUTCOME MEASURES: Threshold of pure-tone tests, age, accompanying symptoms and underlying diseases were compared. The level of final hearing recovery was evaluated by the application of the results of the pure-tone test that was performed at least 3 months after the completion of each treatment. RESULTS: Final hearing recovery rate differed significantly by the type of treatment (P = 0.031). Recovery rates in the PO and combined groups were significantly higher in patients with mild (85.1% and 88.6%, respectively) than with profound (52.8% and 69.0%, respectively) hearing loss (P < 0.05). In contrast, severity and recovery rate were not significantly correlated in the IT group (P > 0.05). Combined treatment yielded significantly higher recovery rates than other treatment modalities in patients without hypertension (HTN) and diabetes mellitus (DM) (P = 0.021). CONCLUSION: In the group treated with combined therapy, better hearing improvement was obtained than in the groups treated with systemic steroid only or with intratympanic steroid injection only without complications. These findings suggest that the combination of systemic administration and intratympanic injection may improve patient prognosis.

Polyethylene glycol bowel preparation does not eliminate the risk of acute renal failure: a population-based case-crossover study.

BACKGROUND AND STUDY AIMS: Polyethylene glycol (PEG) bowel preparations are regarded as effective and safe for colonoscopy; however, recent reports have indicated a risk of acute renal failure (ARF). This population-based case-crossover study evaluated the association between PEG and ARF in screening colonoscopy patients aged ≥ 50 years. PATIENTS AND METHODS: Korean Health Insurance Review and Assessment Service (HIRA) claims data from 1 January 2005 to 31 December 2009 were used in the study. The study population consisted of patients aged ≥ 50 years who were first hospitalized for ARF following colonoscopy involving PEG bowel preparation. For each patient, PEG use in a 1-, 2-, or 4-week period prior to the first hospital admission date for ARF (hazard period) was compared with PEG use in four earlier 1-, 2-, or 4-week control periods. Conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs), adjusting for concomitant medications that could induce ARF. RESULTS: The total number of study patients was 1064 (59 % were male). A greater proportion of patients used PEG during the hazard period than during the control periods (for 4-week time window: 8.8 % vs. 3.2 %). The adjusted ORs for ARF incidence when applying the 1-, 2-, and 4-week periods were 3.1 (95 %CI 2.06 - 4.73), 2.5 (95 %CI 1.76 - 3.53), and 2.1 (95 %CI 1.61 - 4.85), respectively. CONCLUSIONS: The use of PEG was associated with the risk of ARF. Adequate hydration and renal function monitoring should be assured before and after colonoscopy, regardless of the bowel preparation regimen used.

Mutation spectrum and inhibitor risk in 100 Korean patients with severe haemophilia A.

Haemophilia A (HA) is an X-linked recessive bleeding disorder caused by defects in the F8 gene encoding the coagulation factor VIII. Mutation analysis in HA is important to confirm the diagnosis, genotype-phenotype correlations and for genetic counselling and family study. The aim of this study was to detect causative mutations of F8 in severe HA patients in Korea and to correlate the mutation type with the risk of inhibitor development. A total of 100 unrelated Korean patients with severe HA were enrolled for this study. The Nijeman modification of the Bethesda assay was used to determine the presence of inhibitor. Molecular analysis of F8 was performed using a combination of molecular techniques, including long-distance polymerase chain reaction, direct sequencing and multiplex ligation-dependent probe amplification (MLPA). We identified causative mutations in 98% of severe HA patients (98/100). Inv22 and Inv1 mutations were detected in 30 patients and one patient, respectively. A total of 59 unique mutations were identified in 69 non-inversion patients, including 24 novel mutations. The overall prevalence of inhibitor was 26%. Inhibitor risk was highest in patients with large deletion mutations identified using MLPA (100%). Among those with point mutations, the prevalence of inhibitor was highest when the mutation occurred in the A3 and C2 domains (60% and 50%, respectively). The molecular diagnostic strategy involving multiplex PCR, sequencing and dosage analyses identified causative mutations in most cases of severe HA. The high inhibitor risk was associated with large deletion mutations and point mutations in A3 and C2 domains.

Long-term clinical outcomes and risk factors for the occurrence of post-operative complications after cardiovascular surgery in patients with Behçet's disease.

OBJECTIVES: Cardiovascular surgery in patients with Behçet's disease (BD) frequently leads to postoperative complications such as anastomotic leakage, occlusion or pseudoaneurysm. We evaluated the clinical outcomes and related risk factors of postoperative complications in BD patients undergoing cardiovascular surgeries, as well as the long-term efficiency of postoperative immunosuppressive treatment. METHODS: Forty-one patients with BD who had undergone cardiovascular surgery between 1990 and 2009 were studied. We evaluated the patients' clinical data, postoperative complications, and survival rate. Risk factors related to the occurrence of postoperative complications were identified by univariate analysis using the Kaplan-Meier method with the log-rank test and multivariate analysis using the Cox proportional hazards regression model. RESULTS: Fifty-nine operations were performed in 41 patients. During the mean follow-up period of 65.3±48.1 months, complications such as paravalvular leakage, dehiscence, fistula, graft occlusion, or pseudoaneurysm occurred in 29 operations (49.2%). The cumulative occurrence rate of postoperative complication was 10.2% at three months, 32.8% at 12 months, and 43.8% at 24 months. Upon univariate analysis, young age, high Creactive protein levels, lack of postoperative immunosuppression, and short disease duration were identified as significant factors responsible for the occurrence of postoperative complications. In multivariate analysis, postoperative immunosuppression was found to independently lower the risk of complications. The 5-year survival rate was significantly higher in patients with postoperative immunosup immunosuppression than in those without (84.5% vs. 45.0%, p=0.011). CONCLUSIONS: The present study suggests that postoperative immunosuppressive therapy after cardiovascular surgeries in BD patients is important for reducing the development of serious postoperative complications.

Effects of immunization with the rNfa1 protein on experimental Naegleria fowleri-PAM mice.

Free-living Naegleria fowleri causes primary amoebic meningoencephalitis (PAM) in humans and animals. To examine the effect of immunization with Nfa1 protein on experimental murine PAM because of N. fowleri, BALB/c mice were intra-peritoneally or intra-nasally immunized with a recombinant Nfa1 protein. We analysed Nfa1-specific antibody and cytokine induction, and the mean survival time of infected mice. Mice immunized intra-peritoneally or intra-nasally with rNfa1 protein developed specific IgG, IgA and IgE antibodies; the IgG response was dominated by IgG1, followed by IgG2b, IgG2a and IgG3. High levels of the Th1 cytokine, IFN-γ, and the regulatory cytokine, IL-10, were also induced. The mean survival time of mice immunized intra-peritoneally with rNfa1 protein was prolonged compared with controls, (25.0 and 15.5 days, respectively). Similarly, the mean survival time of mice immunized intra-nasally with rNfa1 protein was 24.7 days, compared with 15.0 days for controls.

Lactobacillus intestinalis YT2 restores the gut microbiota and improves menopausal symptoms in ovariectomized rats.

There are many studies focusing on the alleviation of menopausal symptoms; however, little is known about the role of gut microorganisms in menopausal symptoms. Ovariectomized (OVX) rats were administered a novel strain (YT2) of Lactobacillus intestinalis (a species with significantly reduced abundance in OVX rats) and the potential probiotic effect on the improvement of menopausal symptoms was evaluated. Of note, the gut microbial composition completely shifted after ovariectomy in rats. Treatment with L. intestinalis YT2 significantly alleviated menopausal symptoms, such as increased fat mass, decreased bone mineral density, increased pain sensitivity, depression-like behaviour, and cognitive impairment. Additionally, the administration of L. intestinalis YT2 restored the intestinal microbial composition, including an increased Firmicutes/Bacteroides ratio. L. intestinalis YT2 also promoted gut barrier integrity by increasing the mRNA levels of tight junction-related markers. In conclusion, L. intestinalis YT2 treatment alleviated menopausal symptoms via the modulation of the gut microbiota. Importantly, these results suggest that L. intestinalis YT2 should be considered as a therapeutic probiotic agent for menopausal women.

Neuropsychological adverse drug reactions of Remdesivir: analysis using VigiBase, the WHO global database of individual case safety reports.

OBJECTIVE: Although remdesivir (GS-5734) has recently demonstrated clinical benefits against the pandemic outbreak of coronavirus disease 2019 (COVID-19), neuropsychological adverse reactions (ADRs) remain to be examined in real-world settings. Therefore, we aimed to identify and characterize the neuropsychological ADRs associated with remdesivir use. MATERIALS AND METHODS: We obtained data for this international pharmacovigilance cohort study from individual case safety reports (ICSRs) in a World Health Organization database (VigiBase) from the first report on remdesivir on February 17, 2020, until August 30, 2020 (n=1,403,532). ADRs reported to be relevant to remdesivir were compared with the full database by using a Bayesian neural network method to calculate the information component (IC). RESULTS: A total of 2,107 reported cases of neuropsychological ADRs suspected to be associated with remdesivir were identified from among all ICSRs in the database during the observation period. Although 108 neuropsychological ADRs (64 neurologic events and 44 psychologic events) were reported in association with the medication, no statistically significant pharmacovigilance signal could be detected; the IC025 value was negative for all of the neuropsychological dysfunctions (anxiety [n=13, 0.62%], seizures [n=12, 0.57%], lethargy [n=6, 0.28%], agitation [n=5, 0.25%], cerebral infarction [n=3, 0.14%], ischemic stroke [n=3, 0.14%], and hemiparesis [n=3, 0.14%]). CONCLUSIONS: Our study demonstrates that remdesivir, a novel drug applied to the treatment of COVID-19, does not have a significant association with adverse neurologic or psychiatric reactions in the real-world setting.

E/E' ratio is more sensitive than E/A ratio for detection of left ventricular diastolic dysfunction in patients with systemic sclerosis.

OBJECTIVES: To investigate the efficiency of early filling (E) and early diastolic mitral annular velocity (E') ratio (E/E' ratio) assessed by tissue Doppler imaging (TDI) on early detection of diastolic left ventricular (LV) dysfunction in systemic sclerosis (SSc) patients without congestive heart failure (CHF) symptoms. METHODS: Thirty-five Korean SSc patients without CHF symptoms and 35 healthy, age-sex matched controls were studied. Two-dimensional and M-mode echocardiography including conventional and tissue Doppler imaging was performed and pulmonary function test with diffusing capacity of lung for carbon monoxide was assessed. RESULTS: Mean E and late filling (A) ratio (E/A ratio) showed no significant difference between the two groups, while TDI showed that SSc patients had significantly elevated E/E' ratio (10.6+/-4.2 vs. 8.8+/-2.2, p=0.032), in comparison with controls. SSc patients who had taken angiotensin converting enzyme inhibitor or angiotensin II receptor blocker had significantly lower E/E' than those who had not (8.0+/-2.4 vs. 11.9+/-4.3, p=0.01). CONCLUSIONS: E/E' ratio is more sensitive than E/A ratio for identifying LV diastolic dysfunction in SSc patients without CHF symptoms. Furthermore, SSc patients who had received ACEI or ARB treatment showed significantly better preservation of LV diastolic function than those who had not received these medications.

Tipping the immunostimulatory and inhibitory DAMP balance to harness immunogenic cell death.

Induction of tumor cell death is the therapeutic goal for most anticancer drugs. Yet, a mode of drug-induced cell death, known as immunogenic cell death (ICD), can propagate antitumoral immunity to augment therapeutic efficacy. Currently, the molecular hallmark of ICD features the release of damage-associated molecular patterns (DAMPs) by dying cancer cells. Here, we show that gemcitabine, a standard chemotherapy for various solid tumors, triggers hallmark immunostimualtory DAMP release (e.g., calreticulin, HSP70, and HMGB1); however, is unable to induce ICD. Mechanistic studies reveal gemcitabine concurrently triggers prostaglandin E2 release as an inhibitory DAMP to counterpoise the adjuvanticity of immunostimulatory DAMPs. Pharmacological blockade of prostaglandin E2 biosythesis favors CD103+ dendritic cell activation that primes a Tc1-polarized CD8+ T cell response to bolster tumor rejection. Herein, we postulate that an intricate balance between immunostimulatory and inhibitory DAMPs could determine the outcome of drug-induced ICD and pose COX-2/prostaglandin E2 blockade as a strategy to harness ICD.

Anatomical analysis to establish the optimal positioning of an osteotomy for genioglossal advancement: a trial in cadavers.

Genioglossal advancement, which is one of the treatments for obstructive sleep apnoea, can be effective only if it contains enough genial tubercle for an osteotomy. The aim of this study was to establish the position of the genial tubercle and of the optimal osteotomy during genioglossal advancement. Twenty-four adult cadavers with intact bony mandibular structures were included. Five variables were measured: the width and height of the genial tubercle (GTW); the distance from its inferior border to the inferior border of the mandible (IGT-IBM); the distance from the superior border of the genial tubercle to the inferior border of the mandible (SGT-IBM); and the width of the intermental foramen (IMFW). The following mean (SD) (range) measurements were obtained: GTW 7.38 (1.43) (4.5-10.0); GTH 7.94 (1.45) (5.0-10.0); IGT-IBM 7.96 (2.29) (4.0-12.0); SGT-IBM 15.90 (2.29) (12.0-20.0); and IMFW 56.65 (6.44) (43.0-67.0) mm. Of the 24 cadavers, 22 showed evidence of optimal positioning when the osteotomy was placed 2mm higher than the SGT-IBM measured on the inner table. This suggests that an optimal osteotomy, which includes the genial tubercle, may be possible in most patients when the osteotomy is positioned 2mm higher at the SGT-IBM.

Impaired development and dysfunction of endothelial progenitor cells in type 2 diabetic mice.

AIM: Dysfunction of circulating endothelial progenitor cells (EPCs) has been shown to affect the development of microvascular diseases in diabetes patients. The aim of this study was to elucidate the development and mechanical dysfunction of EPCs in type 2 diabetes (T2D). METHODS: The colony-forming capacity of EPCs and differentiation potential of bone marrow (BM) c-Kit(+)/Sca-I(+) lineage-negative mononuclear cells (KSL) were examined in T2D mice, db/db mice and KKAy mice, using EPC colony-forming assay (EPC-CFA). RESULTS: T2D mice had fewer BM stem/progenitor cells, and proliferation of KSL was lowest in the BM of db/db mice. In T2D mice, the frequency of large colony-forming units (CFUs) derived from BM-KSL was highly reduced, indicating dysfunction of differentiation into mature EPCs. Only a small number of BM-derived progenitors [CD34(+) KSL cells], which contribute to the supply of EPCs for postnatal neovascularization, was also found. Furthermore, in terms of their plasticity to transdifferentiate into various cell types, BM-KSL exhibited a greater potential to differentiate into granulocyte macrophages (GMs) than into other cell types. CONCLUSION: T2D affected EPC colony formation and differentiation of stem cells to mature EPCs or haematopoietic cells. These data suggest opposing regulatory mechanisms for differentiation into mature EPCs and GMs in T2D mice.

Anti-endothelial cell antibodies and antiphospholipid antibodies in Takayasu's arteritis: correlations of their titers and isotype distributions with disease activity.

OBJECTIVE: To investigate the prevalence of anti-endothelial cell antibodies (AECA) and antiphospholipid antibodies, and the correlations of their isotype distributions and titers with disease activity in patients with Takayasu's arteritis (TA). METHODS: Forty-seven patients with TA and 30 age- and sex-matched controls were studied. Blood samples were obtained from all patients and they were divided into either active or stable disease groups. Paired samples were available in 18 patients at both active and stable stage, respectively. AECA against human umbilical vein endothelial cells and antiphospholipid antibodies were measured. RESULTS: Forty-two (89.4%) TA patients had AECA, and positivity rates of IgM and IgG AECA were 83.0% and 68.1%, respectively, while those for controls were both 3.3%. The titers of IgM and IgG AECA in patients were significantly higher than those in controls. IgM AECA titers of the active group were significantly higher than those of the stable group, but IgG AECA titers were not. In 18 patients with paired samples, IgM AECA titers at active stage were significantly higher than those at stable stage, but IgG AECA titers were not different between stages. The changes of IgM AECA titers correlated well with those of ESR levels between stages. Antiphospholipid antibodies were detected in only 4 patients with TA, but not in controls. CONCLUSION: IgM AECA and IgG AECA were more prevalent and their titers were higher in patients with TA than in controls, and IgM AECA titers correlated well with the disease activity of TA. Antiphospholipid antibodies were not found significant.

Effects of Na+-Ca2+ exchanger activity on the alpha-amino-3-hydroxy-5-methyl-4-isoxazolone-propionate-induced Ca2+ influx in cerebellar Purkinje neurons.

Variations in intracellular calcium activity ([Ca2+]i) play crucial roles in information processing in Purkinje neurons such as synaptic plasticity. Although Na+-Ca2+ exchanger (NCX) has been shown to participate in the regulation of homeostasis and secretion in neuronal cells, the physiological role of NCX in Purkinje neurons, such as a role in cerebellar synaptic plasticity, is not well understood. NCX in acutely dissociated rat Purkinje neurons was identified by double staining with anti-calbindin D-28k antibody and anti-NCX antibody. The physiological activity of NCX was examined by measuring transient intracellular Ca2+ changes resulting from the Ca2+ influx via reverse mode of NCX (with 0 mM Na+/2.5 mM Ca2+ solutions) and the efflux via the forward mode of NCX (with 140 mM Na+/0 mM Ca2+ solutions). This transient increase in Ca2+ concentration was not elicited in the cells pretreated with NCX antisense oligodeoxynucleotides. And the Ca2+ influx resulting from the reverse mode of NCX was significantly reduced by 2-[2-[4-(4-nitrobenyloxy) phenyl] ethyl] isothiourea methanesulfonate, while the Ca2+ efflux via forward mode was inhibited by bepridil. The physiological role of NCX in synaptic function was studied by measuring Ca2+ transients induced by alpha-amino-3-hydroxy-5-methyl-4-isoxazolone-propionate (AMPA) receptor activation. This AMPA-evoked response was decreased with the inhibition of NCX forward mode and also, to less degree, with the inhibition of reverse mode. In antisense oligodeoxynucleotides pretreated cells, the AMPA-evoked response was also reduced, as was the case in NCX-inhibitor treated cells. The inhibition of NCX activity had depressant effects on Ca2+ transients induced by AMPA receptor activation. These results suggest that NCX plays a physiological role in modulating the activity of cerebellar Purkinje neurons, such as synaptic plasticity, via interaction with AMPA receptors in Purkinje neurons.

Activating protein-1, nuclear factor-kappaB, and serum response factor as novel target molecules of the cancer-amplified transcription coactivator ASC-2.

ASC-2 was recently discovered as a cancer-amplified transcription coactivator molecule of nuclear receptors, which interacts with multifunctional transcription integrators steroid receptor coactivator-1 (SRC-1) and CREB-binding protein (CBP)/p300. Herein, we report the identification of three mitogenic transcription factors as novel target molecules of ASC-2. First, the C-terminal transactivation domain of serum response factor (SRF) was identified among a series of ASC-2-interacting proteins from the yeast two-hybrid screening. Second, ASC-2 specifically interacted with the activating protein-1 (AP-1) components c-Jun and c-Fos as well as the nuclear factor-kappaB (NFkappaB) components p50 and p65, as demonstrated by the glutathione S-transferase pull-down assays as well as the yeast two-hybrid tests. In cotransfection of mammalian cells, ASC-2 potentiated transactivations by SRF, AP-1, and NFkappaB in a dose-dependent manner, either alone or in conjunction with SRC-1 and p300. In addition, ASC-2 efficiently relieved the previously described transrepression between nuclear receptors and either AP-1 or NFkappaB. Overall, these results suggest that the nuclear receptor coactivator ASC-2 also mediates transactivations by SRF, AP-1, and NFkappaB, which may contribute to the putative, ASC-2-mediated tumorigenesis.

Two distinct nuclear receptor-interaction domains and CREB-binding protein-dependent transactivation function of activating signal cointegrator-2.

ASC-2 is a recently isolated transcriptional cointegrator molecule, which is amplified in human cancers and stimulates transactivation by nuclear receptors, AP-1, nuclear factor kappaB (NFkappaB), serum response factor (SRF), and numerous other transcription factors. ASC-2 contained two nuclear receptor-interaction domains, both of which are dependent on the integrity of their core LXXLL sequences. Surprisingly, the C-terminal LXXLL motif specifically interacted with oxysterol receptor LXRss, whereas the N-terminal motif bound a broad range of nuclear receptors. These interactions appeared to be essential because a specific subregion of ASC-2 including the N- or C-terminal LXXLL motif acted as a potent dominant negative mutant with transactivation by appropriate nuclear receptors. In addition, the autonomous transactivation domain (AD) of ASC-2 was found to consist of three separable subregions; i.e. AD1, AD2, and AD3. In particular, AD2 and AD3 were binding sites for CREB binding protein (CBP), and CBP-neutralizing E1A repressed the autonomous transactivation function of ASC-2. Furthermore, the receptor transactivation was not enhanced by ASC-2 in the presence of E1A and significantly impaired by overexpressed AD2. From these results, we concluded that ASC-2 directly binds to nuclear receptors and recruits CBP to mediate the nuclear receptor transactivation in vivo.