The utility of endoscopy prior to bariatric surgery: an 11-year retrospective analysis of 885 patients.

INTRODUCTION: Our aim was to evaluate the diagnostic yield of routine preoperative esophagogastroduodenoscopy (p-EGD) in patients undergoing bariatric surgery. Many medical problems that are common in patients with obesity, including gastroesophageal reflux disease (GERD) and hiatal hernias, have important implications for patients undergoing bariatric surgery. While p-EGD is considered standard of care prior to antireflux surgery, the role of p-EGD in bariatric surgery patients remains controversial. METHODS AND PROCEDURES: We performed a retrospective chart review of 885 patients who underwent primary bariatric surgery at a university hospital-based bariatric surgery program between March 2011 and February 2022. Clinical history, demographics, and preoperative EGD reports were reviewed for abnormal findings. RESULTS: Of the 885 patients evaluated in this study, one or more abnormal EGD findings were observed in 83.2% of patients. More than half of our patients (54.7%) presented with history of heartburn, reflux, or GERD. EGD findings demonstrated a hernia in 43.1% of patients [(Type I: 40.6%; Type II: 0.5%; Type III: 2.1%)]. 68.0% of patients were biopsied. Among patients who were biopsied, other findings included gastritis (32.4%), esophagitis (8.0%), eosinophilic esophagitis (4.7%), or duodenitis (2.7%). We found ulcers in 6.7% of patients. Pathology was consistent with H. pylori in 9.8% of biopsies taken and consistent with BE in 2.7%. Following routine p-EGD, 11.2% of patients were placed on PPI and 8.3% were recommended to stop NSAIDs. CONCLUSION: Gastroesophageal reflux disease and associated pathology are common in the bariatric population. Preoperative EGD in patients undergoing bariatric surgery frequently identifies clinically significant UGI pathology. This may have important implications for medical and surgical management. Given the rate of abnormal preoperative endoscopic findings in obese patients, the work-up for bariatric surgery should align with the current recommendations for foregut surgery.

Prevalence and Symptom Burden of Nasal Polyps in a Large Austrian Population.

BACKGROUND: Although chronic rhinosinusitis with nasal polyps is a common inflammatory condition with significant morbidity and financial cost, information regarding prevalence and disease burden of this condition is scarce. OBJECTIVE: In this study, we determined nasal polyp prevalence, polyp grade, concomitant disease, and symptom burden in more than 10,000 central European subjects. METHODS: In this retrospective, cross-sectional study, 10,259 patients who had undergone routine examination of their nose by nasal endoscopy during a visit at a publicly accessible ear, nose, throat outpatient facility in Vienna were included. Patient details including presenting complaint, nasal symptoms, polyp score, age, gender, treatment, asthma, and allergic status were extracted retrospectively. A detailed questionnaire including history of nasal symptoms, Sino-Nasal Outcome Test-20 German Adapted Version, and visual analog scale was available for 101 patients with nasal polyps. RESULTS: Nasal polyps were detected in 189 of the 10,259 (1.84%) patients. The calculated prevalence of polyps in Austria, adjusted for age and gender, was 1.95%. The average total polyp score (TPS) was 3.4, and 72.5% had a TPS of ≤4, with males and asthmatics having significantly larger polyps. Questionnaire analysis revealed that 67% suffered from a low symptom burden of ≤36. According to current European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS) guidelines, 6% of patients with polyps met and another 8% potentially fulfilled the eligibility criteria for biological therapy. CONCLUSION: Nasal polyp prevalence was calculated to be 1.95% of the Austrian population. Large polyps (TPS >4) were found in 25%, 33% suffered from a high nasal symptom burden, and between 6% and 14% of patients with polyps would be eligible for biological therapy according to EPOS guidelines.

Self-Pay Payer Status Predicts Long-Term Loss to Follow-Up After Bariatric Surgery.

PURPOSE: In spite of widespread recommendations for lifelong patient follow-up with a bariatric provider after bariatric surgery, attrition to follow-up is common. Over the past two decades, many programs have sought to expand access to care for patients lacking insurance coverage for bariatric surgery by offering "self-pay" packages; however, the impact of this financing on long-term follow-up is unclear. We sought to determine whether payer status impacts loss to follow-up within 1 year after bariatric surgery. MATERIALS AND METHODS: Records of 554 consecutive patients undergoing bariatric surgery who were eligible for 1-year post-surgical follow-up between 2014 and 2019 were retrospectively reviewed. Multiple logistic regression examined the relationship between demographics, psychological variables, payer status, and loss to follow-up. RESULTS: Self-pay status more than tripled the odds of loss to follow-up (OR = 3.44, p < 0.01) at 1 year following surgery. Males had more than double the odds of attrition (OR = 2.43, p < 0.01), and members of racial and ethnic minority groups (OR = 2.51, p < 0.05) were more likely to experience loss. CONCLUSIONS: Self-pay patients, males and members of racial and ethnic minority groups, may face additional barriers to long-term access to postoperative bariatric care. Further investigation is greatly needed to develop strategies to overcome barriers to and disparities in long-term post-surgical care for more frequently lost groups.

Rocaglamide breaks TRAIL-resistance in human multiple myeloma and acute T-cell leukemia in vivo in a mouse xenogtraft model.

Multiple myeloma (MM) is an incurable malignancy by the presently known therapies. TRAIL is a promising anticancer agent that virtually not shows any toxicity to normal cells. We have recently carried out clinical trials with a human circularly permuted TRAIL, CPT, against MM saw a partial response in approximate 20-30% of patients. In the current study, we investigated the cause of CPT resistance and revealed that the majority of the MM patients express elevated levels of c-FLIP. Knockdown of c-FLIP expression by siRNA alone was sufficient to increase CPT-mediated apoptosis in a CPT-resistant human MM cell line U266. To overcome CPT resistance, we investigated the combination of CPT with Rocaglamides(s) in MM which has been shown to inhibit c-FLIP expression in vitro. We show that Rocaglamide(s) overcomes CPT resistance in U266 in vitro and significant increases in anti-tumor efficacies of CPT in mice xenografted with U266. Similar results were also obtained in mice xenografted with the CPT-resistant human acute T-cell leukemia cell line Molt-4. Our study suggests that the combination of Rocaglamide(s) with CPT may provide a more efficient treatment against myeloma and leukemia.

The anticancer phytochemical rocaglamide inhibits Rho GTPase activity and cancer cell migration.

Chemotherapy is one of the pillars of anti-cancer therapy. Although chemotherapeutics cause regression of the primary tumor, many chemotherapeutics are often shown to induce or accelerate metastasis formation. Moreover, metastatic tumors are largely resistant against chemotherapy. As more than 90% of cancer patients die due to metastases and not due to primary tumor formation, novel drugs are needed to overcome these shortcomings. In this study, we identified the anticancer phytochemical Rocaglamide (Roc-A) to be an inhibitor of cancer cell migration, a crucial event in metastasis formation. We show that Roc-A inhibits cellular migration and invasion independently of its anti-proliferative and cytotoxic effects in different types of human cancer cells. Mechanistically, Roc-A treatment induces F-actin-based morphological changes in membrane protrusions. Further investigation of the molecular mechanisms revealed that Roc-A inhibits the activities of the small GTPases RhoA, Rac1 and Cdc42, the master regulators of cellular migration. Taken together, our results provide evidence that Roc-A may be a lead candidate for a new class of anticancer drugs that inhibit metastasis formation.

HTLV-1-associated adult T cell leukemia is highly susceptible to Navitoclax due to enhanced Bax expression.

Over-expression of Bcl-2, Bcl-xL and Bcl-w is frequently associated with cancer resistance to chemotherapy. Navitoclax (ABT-263), an orally bio-available small-molecule mimetic of the Bcl-2 homology domain 3, specifically inhibits Bcl-2, Bcl-xL and Bcl-w. Despite promising results obtained from the clinical trials, the use of Navitoclax in patients is dose-limited due to induction of death of platelets via inhibition of Bcl-xL and subsequent thrombocytopenia. This side effect limits the use of Navitoclax in low doses and to very sensitive tumors. In this study, we show that HTLV-1-associated adult T-cell leukemia/lymphoma (ATL) cells, which over-express Bcl-2, Bcl-xL and Bcl-w, show a 10- to 20-fold higher sensitivity (EC50 = ∼ 25-50 nM) to Navitoclax compared to non-HTLV-1-associated leukemic cells (EC50 = ∼ 1 µM). Investigation of the molecular mechanisms revealed that the HTLV-1 oncogenic protein Tax up-regulates expression of the pro-apoptotic protein Bax which enhances the therapeutic efficacy of Navitoclax. In addition, we show that agents that inhibit the transcription elongation or translation initiation such as Wogonin and Roc-A can further decrease the effective dose of Navitoclax. Our study suggests that HTLV-1 ATL may be a good candidate disease for low dose Navitoclax therapy and probably with less risk of thrombocytopenia.

Mangrove dolabrane-type of diterpenes tagalsins suppresses tumor growth via ROS-mediated apoptosis and ATM/ATR-Chk1/Chk2-regulated cell cycle arrest.

Natural compounds are an important source for drug development. With an increasing cancer rate worldwide there is an urgent quest for new anti-cancer drugs. In this study, we show that a group of dolabrane-type of diterpenes, collectively named tagalsins, isolated from the Chinese mangrove genus Ceriops has potent cytotoxicity on a panel of hematologic cancer cells. Investigation of the molecular mechanisms by which tagalsins kill malignant cells revealed that it induces a ROS-mediated damage of DNA. This event leads to apoptosis induction and blockage of cell cycle progression at S-G2 phase via activation of the ATM/ATR-Chk1/Chk2 check point pathway. We further show that tagalsins suppress growth of human T-cell leukemia xenografts in vivo. Tagalsins show only minor toxicity on healthy cells and are well tolerated by mice. Our study shows a therapeutic potential of tagalsins for the treatment of hematologic malignancies and a new source of anticancer drugs.

Molecular Basis of Transcription-Coupled Pre-mRNA Capping.

Capping is the first step in pre-mRNA processing, and the resulting 5'-RNA cap is required for mRNA splicing, export, translation, and stability. Capping is functionally coupled to transcription by RNA polymerase (Pol) II, but the coupling mechanism remains unclear. We show that efficient binding of the capping enzyme (CE) to transcribing, phosphorylated yeast Pol II (Pol IIp) requires nascent RNA with an unprocessed 5'-triphosphate end. The transcribing Pol IIp-CE complex catalyzes the first two steps of capping, and its analysis by mass spectrometry, cryo-electron microscopy, and protein crosslinking revealed the molecular basis for transcription-coupled pre-mRNA capping. CE docks to the Pol II wall and spans the end of the RNA exit tunnel to position the CE active sites for sequential binding of the exiting RNA 5' end. Thus, the RNA 5' end triggers its own capping when it emerges from Pol II, to ensure seamless RNA protection from 5'-exonucleases during early transcription.

Electronic medical record-based performance improvement project to document and reduce excessive cardiac troponin testing.

BACKGROUND: We assessed the utilization rationale behind provider ordering of cardiac troponin I (cTnI) testing for the diagnosis of myocardial infarction after implementation of a hospital-wide serial order protocol. METHODS: During 2 months in 2013, any request for additional cTnI testing within 30 days of the initial serial cTnI order prompted an electronic health record best practice alert (BPA), which included clinical decision support that could be bypassed by giving a clinical indication. cTnI orders were not limited (timing, number), and upon BPA, trigger data was collected for clinical indications and actions, patient stay (duration, location), International Classification of Diseases, Revision 9 diagnosis, cTnI orders, and timing of cTnI measurements. RESULTS: The BPA was triggered 1477 times by 423 providers who cared for 702 patients. There were a mean of 3.6 cTnI results per patient, 2.1 BPAs per patient, and 1.2 visits per patient. Providers (42% of whom were residents) acknowledged and overrode the BPA 97% of the time. In response to the BPA, 65% of providers selected a prepared rationale: 64% acute coronary syndrome/ST-elevation myocardial infarction/non-ST-elevation myocardial infarction; 30% demand ischemia; and 6% non-ACS myocardial necrosis. Of the remaining 35% of providers, 71% listed no rationale for their additional cTnI orders. Of patients with a BPA, 93% had non-ACS-related primary International Classification of Diseases, Revision 9 diagnosis, and 58% of the time, patients' cTnI results never increased during their stay. In 53% of cases, BPAs were generated by a request for an additional cTnI series when <2 results were available. CONCLUSIONS: Providers largely ignored the BPA that warned of potential overutilization of cTnI testing independent of diagnosis, including ACS.

Targeting CDK9 by wogonin and related natural flavones potentiates the anti-cancer efficacy of the Bcl-2 family inhibitor ABT-263.

Tumor initiation, progression and resistance to therapies are tightly associated with over-expression of anti-apoptotic proteins Bcl-2, Bcl-x(L), Bcl-w and Mcl-1. ABT-263 (Navitoclax), an orally bio-available small-molecule mimetic of the Bcl-2 homology domain 3, inhibits Bcl-2, Bcl-x(L), and Bcl-w and has shown anti-cancer effects mainly on lymphomas and lymphocytic leukemia. Despite promising results obtained from the clinical trials, the use of ABT-263 in patients is dose-limited due to causing thrombocytopenia via inhibition of Bcl-x(L) in platelets. ABT-199 specifically inhibits Bcl-2; however, its use is limited to tumors over-expressing only Bcl-2. Besides, many tumors resist treatment due to high levels of Mcl-1 expression or develop resistance via up-regulation of Mcl-1 during long-term exposure. These obstacles highlight the demand to improve the ABT-263-based therapy. In this study, we show that anti-cancer flavones, e.g., wogonin, baicalein, apigenin, chrysin and luteolin enhance ABT-263-induced apoptosis in different cancer cell lines and in primary AML and ALL cells by down-regulation of Mcl-1 expression. Importantly, wogonin does not enhance the toxicity of ABT-263 to proliferating normal T cells and thrombocytes. Wogonin also potentiates the lethality of ABT-263 in cancer cells which have acquired resistance to ABT-263. Furthermore, we show that combination of wogonin with ABT-263 promotes in vivo tumor regression in a human T-cell leukemia xenograft mouse model. Our study demonstrates that wogonin (and related flavones) reduce the effective dose of ABT-263 thereby possibly decreasing the risk of adverse side effects.

The Wilms' tumor suppressor WT1 enhances CD95L expression and promotes activation-induced cell death in leukemic T cells.

The role of Wilms' tumor suppressor 1 (WT1) in leukemogenesis has been investigated mostly in acute (AML) and chronic (CML) myeloid leukemias. So far, its oncogenic role has been controversially discussed because both overexpression and inactivating mutations are found. A recent study on primary samples from patients with acute T-cell leukemia (T-ALL) revealed that most of them do not express WT1 proteins although they express WT1 mRNA. In our study, we investigated WT-1 expression in ten T-ALL cell lines established from leukemia/lymphoma patients. We show that consistent with the finding in primary T-ALL cells, most of the leukemic T-cell lines tested do not overexpress WT1 proteins. We found that leukemic T-cells overexpressing WT1 protein produce higher levels of CD95L and show elevated CD95L-mediated activation-induced cell death (AICD) compared to cells lacking or expressing low levels of WT1. Ectopic expression of WT1 in the WT1-nonexpressing leukemic T-cell line increases CD95L expression and elevates activation-induced apoptosis, whereas silencing WT1 expression in the WT1-overexpressing leukemic T-cell line by siRNA confers reduced CD95L expression and reduction in AICD. Chromatin immunoprecipitation and luciferase-promoter reporter analysis demonstrate that WT1 binds to and enhances CD95L promoter activity through the Egr-binding sites. Our study provides a new role of WT1 in regulation of CD95L-mediated cell death.

The natural anticancer compound rocaglamide selectively inhibits the G1-S-phase transition in cancer cells through the ATM/ATR-mediated Chk1/2 cell cycle checkpoints.

Targeting the cancer cell cycle machinery is an important strategy for cancer treatment. Cdc25A is an essential regulator of cycle progression and checkpoint response. Over-expression of Cdc25A occurs often in human cancers. In this study, we show that Rocaglamide-A (Roc-A), a natural anticancer compound isolated from the medicinal plant Aglaia, induces a rapid phosphorylation of Cdc25A and its subsequent degradation and, thereby, blocks cell cycle progression of tumor cells at the G1-S phase. Roc-A has previously been shown to inhibit tumor proliferation by blocking protein synthesis. In this study, we demonstrate that besides the translation inhibition Roc-A can induce a rapid degradation of Cdc25A by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway. However, Roc-A has no influence on cell cycle progression in proliferating normal T lymphocytes. Investigation of the molecular basis of tumor selectivity of Roc-A by a time-resolved microarray analysis of leukemic vs. proliferating normal T lymphocytes revealed that Roc-A activates different sets of genes in tumor cells compared with normal cells. In particular, Roc-A selectively stimulates a set of genes responsive to DNA replication stress in leukemic but not in normal T lymphocytes. These findings further support the development of Rocaglamide for antitumor therapy.

Targeting the IL-4/IL-13 signaling pathway sensitizes Hodgkin lymphoma cells to chemotherapeutic drugs.

Hodgkin/Reed-Sternberg lymphoma (HL) is a clonal B-cell-related malignancy. Although many patients with HL can be cured by the current regimen of high-dose multi-agent chemotherapy, the treatment causes high risks of later pathologies including secondary malignancies. This fact highlights the demand to develop rational treatment for HL. Survival and growth of HL cells are largely dependent on their microenvironment. In this study, using the HL cell lines L1236 and KM-H2 as model systems, we investigated the role of IL-4/IL-13 signaling in regulation of drug sensitivity and resistance in HL. We show that specific blocking of IL-4 and IL-13-mediated STAT6 activation by either an IL-4-binding fusion protein APG598 or an IL-4R antagonist APG201 (R121D/Y124D) renders HL cells more prone to apoptotic killing by chemotherapeutic drugs such as Mitomycin C, 5-Fluorouracil, Etopside, Doxorubicin and Paclitaxel. This effect is due to inhibition of STAT6-mediated elevation of expression of the anti-apoptotic Bcl-2 family protein Bcl-xL. Employing ChIP analysis in combination with APG201 or STAT6-specific siRNA we identified a defined STAT6-binding site in the Bcl-xL promoter region from -1967 to -1957 of the transcription start site. Our data demonstrate that the IL-4/IL-13-STAT6-Bcl-xL axis may be an important target for HL treatment. This study also suggests that combination of classical chemotherapeutic drugs with the IL-4/IL-13 antagonists may enhance efficacy and reduce risks of toxicity from high dose of drugs in HL treatment.

The natural anticancer compounds rocaglamides inhibit the Raf-MEK-ERK pathway by targeting prohibitin 1 and 2.

Rocaglamides are potent natural anticancer products that inhibit proliferation of various cancer cells at nanomolar concentrations. We have recently shown that these compounds prevent tumor growth and sensitize resistant cancer cells to apoptosis by blocking the MEK-ERK-eIF4 pathway. However, their direct molecular target(s) remain(s) unknown. In this study, using an affinity chromatography approach we discovered that prohibitin (PHB) 1 and 2 are the direct targets of rocaglamides. Binding of rocaglamides to PHB prevents interaction between PHB and CRaf and, thereby, inhibits CRaf activation and subsequently CRaf-MEK-ERK signaling. Moreover, knockdown of PHB mimicked the effects of rocaglamides on the CRaf-MEK-ERK pathway and cell cycle progression. Thus, our finding suggests that rocaglamides are a new type of anticancer agent and that they may serve as a small-molecular tool for studying PHB-mediated cellular processes.

Curcumin suppresses T cell activation by blocking Ca2+ mobilization and nuclear factor of activated T cells (NFAT) activation.

Curcumin is the active ingredient of the spice turmeric and has been shown to have a number of pharmacologic and therapeutic activities including antioxidant, anti-microbial, anti-inflammatory, and anti-carcinogenic properties. The anti-inflammatory effects of curcumin have primarily been attributed to its inhibitory effect on NF-κB activity due to redox regulation. In this study, we show that curcumin is an immunosuppressive phytochemical that blocks T cell-activation-induced Ca(2+) mobilization with IC(50) = ∼12.5 µM and thereby prevents NFAT activation and NFAT-regulated cytokine expression. This finding provides a new mechanism for curcumin-mediated anti-inflammatory and immunosuppressive function. We also show that curcumin can synergize with CsA to enhance immunosuppressive activity because of different inhibitory mechanisms. Furthermore, because Ca(2+) is also the secondary messenger crucial for the TCR-induced NF-κB signaling pathway, our finding also provides another mechanism by which curcumin suppresses NF-κB activation.

Wogonin and related natural flavones overcome tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) protein resistance of tumors by down-regulation of c-FLIP protein and up-regulation of TRAIL receptor 2 expression.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that kills various tumor cells without damaging normal tissues. However, many cancers remain resistant to TRAIL. To overcome TRAIL resistance, combination therapies using sensitizers of the TRAIL pathway would be an efficacious approach. To investigate potential sensitizers of TRAIL-induced apoptosis, we used TRAIL-resistant human T cell leukemia virus type 1 (HTLV-1)-associated adult T cell leukemia/lymphoma (ATL) cells as a model system. So far, HTLV-1-associated ATL is incurable by presently known therapies. Here, we show that wogonin and the structurally related natural flavones apigenin and chrysin break TRAIL resistance in HTLV-1-associated ATL by transcriptional down-regulation of c-FLIP, a key inhibitor of death receptor signaling, and by up-regulation of TRAIL receptor 2 (TRAIL-R2). This effect is mediated through transcriptional inhibition of the p53 antagonist murine double minute 2 (Mdm2), leading to an increase in p53 levels and, consequently, to up-regulation of the p53 target gene TRAIL-R2. We also show that these flavones can sensitize to TNFα- and CD95-mediated cell death. Furthermore, we show that wogonin, apigenin, and chrysin also enhance TRAIL-mediated apoptosis in other human cancer cell lines including breast cancer cell line MDA-MB-231, colon cancer cell line HT-29, hepatocellular carcinoma cell line HepG2, melanoma cell line SK-MEL-37, and pancreatic carcinoma cell line Capan-1 by the same mechanism. Thus, our study suggests the potential use of these flavones as an adjuvant for TRAIL-mediated anticancer therapy.

Rocaglamide and a XIAP inhibitor cooperatively sensitize TRAIL-mediated apoptosis in Hodgkin's lymphomas.

Although most of the patients with Hodgkin's lymphoma (HL) can be cured by the current regimen of high-dose multiagent chemotherapy, the treatment causes high risks of later toxicities including secondary malignancies. Therefore, new rational strategies are needed for HL treatment. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent due to its tumor selectivity and its lack of toxicity for normal cells. Unfortunately, many cancers remain resistant to TRAIL including HL. HL is characterized by enhanced expression of cellular caspase-8 (FLICE)-inhibitory protein (c-FLIP) and X-linked inhibitor of apoptosis (XIAP), which block receptor-mediated apoptosis by inhibiting caspase-8 and caspase-3, respectively. We have recently discovered the herbal compound Rocaglamide, which breaks TRAIL-resistance in acute T cell leukemia through inhibition of c-FLIP expression. We have also shown that small molecule XIAP inhibitors can sensitize TRAIL-mediated apoptosis in several resistant tumors. However, whether targeting XIAP or c-FLIP is also a suitable strategy to prime HL cells for TRAIL-induced apoptosis has not yet been investigated. In our study, we show that Rocaglamide suppresses c-FLIP expression in HL cells in a dose- and time-dependent manner. However, downregulation of c-FLIP alone was not sufficient to sensitize TRAIL-induced apoptosis in HL cells. Similarly, treatment of HL cells with a small molecule XIAP inhibitor resulted in a moderate induction of apoptosis. However, inhibition of XIAP alone was also not sufficient to enhance TRAIL-induced cell death. Synergistic increase in TRAIL-mediated killing of HL cells was only obtained by combination of Rocaglamide and XIAP inhibitors. Our study demonstrates that targeting both c-FLIP and XIAP are necessary for an efficient treatment of HL.

Early growth response protein-1 (Egr-1) is preferentially expressed in T helper type 2 (Th2) cells and is involved in acute transcription of the Th2 cytokine interleukin-4.

The early growth response gene product Egr-1 has been shown to have great impact on growth, proliferation, and differentiation in a wide variety of cells, including T cells. In this study, we show that Egr-1 is rapidly induced upon T cell stimulation and is expressed predominantly in T helper type 2 (Th2) compared with type 1 (Th1) cells. We further investigate the role of Egr-1 in regulation of the Th2 cytokine interleukin-4 (IL-4) expression. IL-4 is a key Th2 cytokine that regulates humoral immunity and also causes allergic inflammation. Regulation of IL-4 gene transcription in Th2 cells has been shown to be controlled by multiple T cell receptor (TCR)-induced transcription factors. However, only a few transcription factors were shown to be selectively induced in differentiated Th2 cells in response to TCR stimulation. Chromatin immunoprecipitation analysis demonstrates that Egr-1 binds to the IL-4 promoter in vivo upon T cell stimulation. Ectopic expression of Egr-1 enhances endogenous IL-4 mRNA expression and elevates IL-4 promoter activity. We also show that Egr-1, nuclear factor of activated T cell, and NF-kappaB cooperatively bind to an NFAT/NF-kappaB-overlapping IL-4 enhancer element and activate the IL-4 promoter synergistically. Furthermore, we show that antisense oligonucleotides that knock down Egr-1 expression attenuate IL-4 transcription. Our study provides the first evidence that Egr-1 protein is differentially expressed in Th1 and Th2 cells and is involved in the acute phase of the IL-4 transcription in response to TCR stimulation.

YidC and Oxa1 form dimeric insertion pores on the translating ribosome.

The YidC/Oxa1/Alb3 family of membrane proteins facilitates the insertion and assembly of membrane proteins in bacteria, mitochondria, and chloroplasts. Here we present the structures of both Escherichia coli YidC and Saccharomyces cerevisiae Oxa1 bound to E. coli ribosome nascent chain complexes determined by cryo-electron microscopy. Dimers of YidC and Oxa1 are localized above the exit of the ribosomal tunnel. Crosslinking experiments show that the ribosome specifically stabilizes the dimeric state. Functionally important and conserved transmembrane helices of YidC and Oxa1 were localized at the dimer interface by cysteine crosslinking. Both Oxa1 and YidC dimers contact the ribosome at ribosomal protein L23 and conserved rRNA helices 59 and 24, similarly to what was observed for the nonhomologous SecYEG translocon. We suggest that dimers of the YidC and Oxa1 proteins form insertion pores and share a common overall architecture with the SecY monomer.