Involvement of superoxide in malaoxon-induced toxicity in primary cultures of cortical neurons.

Organophosphorus compounds (OP) represent a class of insecticides that are used most globally. The neurotoxic effects are attributed mainly to acetylcholinesterase (AChE) enzyme inhibition, which is responsible for cholinergic manifestations in individuals acutely exposed to OP. However, AChE inhibition alone cannot account for the wide range of symptoms that were reported following OP exposures. In agreement with this, evidence shows that non-cholinergic events may be mechanistically linked to OP-induced neurotoxicity. The aim of this study was to investigate the potential occurrence of oxidative stress as a critical step in the toxicity induced by the OP malaoxon(MAL) using primary cultures of mouse cortical neurons, as well as to distinguish MAL-induced oxidative stress and cell toxicity from an action on AChE blockade. Primary cultures of mouse cortical neurons were treated with MAL (0.01; 0.1; 1; 10; or 100 µM) at varying time points (1, 3, 6, 24, 48, or 144 hr) and the following biochemical parameters determined including cell viability, AChE activity, and superoxide production. MAL significantly reduced cell viability in a concentration- and time-dependent manner. Of note, 1 µM MAL significantly inhibited (approximately 75%) AChE activity after 48 hr incubation. Pralidoxime (PRAL) (600 µM), a classical AChE reactivator, significantly protected against MAL-induced AChE blockade; however, PRAL did not affect MAL-mediated fall in cellular viability, indicating that AChE inhibition is not necessarily correlated with insecticide-induced decrease in cell survival. MAL-induced diminished cell viability was preceded by a significant increase in superoxide anion production. The antioxidant agent ascorbic acid (AA) (200 µM), which significantly protected against MAL-induced superoxide anion production, did not alter MAL-induced AChE inhibition and significantly prevented insecticide-mediated fall in cell survival. Data show that increased superoxide anion production is an event that precedes MAL-induced cell toxicity in primary cultures of mouse cortical neurons. Based on the preventative effects of AA against MAL-mediated superoxide anion production and reduced cell viability, evidence indicates that oxidative stress represents an important step mediating MAL-induced toxicity in neurons and that AChE inhibition is not necessarily correlated with lowered cell survival noted in insecticide-exposed cells.

Update on traumatic acute spinal cord injury. Part 1. / Actualización en lesión medular aguda postraumática. Parte 1.

Traumatic spinal cord injury requires a multidisciplinary approach both for specialized treatment of the acute phase and for dealing with the secondary complications. A suspicion or diagnosis of spinal cord injury is the first step for a correct management. A review is made of the prehospital management and characteristics of the acute phase of spinal cord injury. Respiratory monitoring for early selective intubation, proper identification and treatment of neurogenic shock are essential for the prevention of secondary spinal cord injury. The use of corticosteroids is currently not a standard practice in neuroprotective treatment, and hemodynamic monitoring and early surgical decompression constitute the cornerstones of adequate management. Traumatic spinal cord injury usually occurs as part of multiple trauma, and this can make diagnosis difficult. Neurological examination and correct selection of radiological exams prevent delayed diagnosis of spinal cord injuries, and help to establish the prognosis.

Update on traumatic acute spinal cord injury. Part 2. / Actualización en lesión medular aguda postraumática. Parte 2.

The aim of treatment in acute traumatic spinal cord injury is to preserve residual neurologic function, avoid secondary injury, and restore spinal alignment and stability. In this second part of the review, we describe the management of spinal cord injury focusing on issues related to short-term respiratory management, where the preservation of diaphragmatic function is a priority, with prediction of the duration of mechanical ventilation and the need for tracheostomy. Surgical assessment of spinal injuries based on updated criteria is discussed, taking into account that although the type of intervention depends on the surgical team, nowadays treatment should afford early spinal decompression and stabilization. Within a comprehensive strategy in spinal cord injury, it is essential to identify and properly treat patient anxiety and pain associated to spinal cord injury, as well as to prevent and ensure the early diagnosis of complications secondary to spinal cord injury (thromboembolic disease, gastrointestinal and urinary disorders, pressure ulcers).

Endocannabinoids participate in placental apoptosis induced by hypoxia inducible factor-1.

During pregnancy, apoptosis is a physiological event critical in the remodeling and aging of the placenta. Increasing evidence has pointed towards the relevance of endocannabinoids (ECs) and hypoxia as modulators of trophoblast cell death. However, the relation between these factors is still unknown. In this report, we evaluated the participation of ECs in placental apoptosis induced by cobalt chloride (CoCl2), a hypoxia mimicking agent that stabilizes the expression of hypoxia inducible factor-1 alpha (HIF-1α). We found that HIF-1α stabilization decreased FAAH mRNA and protein levels, suggesting an increase in ECs tone. Additionally, CoCl2 incubation and Met-AEA treatment reduced cell viability and increased TUNEL-positive staining in syncytiotrophoblast layer. Immunohistochemical analysis demonstrated Bax and Bcl-2 protein expression in the cytoplasm of syncytiotrophoblast. Finally, HIF-1α stabilization produced an increase in Bax/Bcl-2 ratio, activation of caspase 3 and PARP cleavage. All these changes in apoptotic parameters were reversed with AM251, a CB1 antagonist. These results demonstrate that HIF-1α may induce apoptosis in human placenta via intrinsic pathway by a mechanism that involves activation of CB1 receptor suggesting a role of the ECs in this process.

Within-species variation in long-term trajectories of growth, fecundity and mortality in the Collembola Folsomia candida.

Senescence--the progressive deterioration of organisms with age--affects many traits of which survival and reproduction are the most commonly studied. Recent comparative studies have revealed a remarkable amount of variation in the patterns of ageing across the tree of life. This between-species diversity raises many questions about the evolution of senescence and of the shapes of the life-history age trajectories. Here, we study how the different components of the shapes of these life-history age trajectories can vary within a single species to shed light on the possible constraints involved in their evolution. To do so, we closely followed in controlled laboratory conditions, and for more than 450 days, the mortality, body length and fecundity of small cohorts of two clonal lineages of the Collembola Folsomia candida. We studied three components of the adult mortality trajectory: the baseline mortality, onset and speed of senescence. We found that they can differ between strains of a single species in such a way that, remarkably, an increased life expectancy is not synonymous with a delayed senescence: the strain that grows bigger has the longest life expectancy but suffers from a precocious senescence. We observed marked differences between the strains in the asymptotic body length and reproductive investment. More generally, our results highlight the importance of finely describing the long-term trajectories of several life-history traits in order to better understand how the patterns of senescence have been shaped by natural selection.

TNF-alpha gene polymorphisms can help to predict response to etanercept in psoriatic patients.

BACKGROUND: Genetic factors might have a role for lack of therapeutic response to anti-TNF-alpha agents, as previously suggested in patients with rheumatoid arthritis and inflammatory bowel disease. OBJECTIVES: We evaluated the role of the main TNF-alpha polymorphisms (-238G>A, -308G>A, -857C>T) in predicting the response to etanercept, an anti-TNF-alpha fusion protein. MATERIAL AND METHODS: Genomic DNA was extracted from buccal epithelial cells in a series of 97 psoriatic patients who received etanercept for at least 3 months. Patients were classified as responders, if they achieved a PASI improvement ≥ 75% after 12 weeks of etanercept treatment, and non-responders, if PASI improvement was <75%. Single-nucleotide polymorphisms (SNPs) in TNF-alpha gene (-238G>A, -308G>A, -857C>T) were genotyped by PCR restriction fragment length polymorphism (RFLP) assays. RESULTS: We found that patients heterozygous (GA) for the -238G>A polymorphism were more likely not responsive to therapy compared to the GG genotype. In fact, the GA genotype was found in 5/59 (8.5%) responders and in 14/38 (36.8%) non-responders (P = 0.001). A significant relationship with therapy was also observed for the -308G>A polymorphisms. In fact, the GG, GA and AA genotypes were detected in 48 (81.4%), 9 (15.3%) and 2 (3.4%) of the 59 responders and in 22 (57.9%), 11 (28.9%) and 5 (13.2%) of the 38 non-responder patients (P = 0.03). No association with therapy was observed for the -857C>T polymorphisms. CONCLUSION: Our study supports the role of TNF-alpha polymorphisms in predicting the response to anti-TNF-alpha agents. In particular, we found that the presence of -238G>A and -308G>A polymorphisms is associated with poor response to a 3-month therapy with etanercept. However, our data have yet to be validated in larger cohorts.

Peritoneal Submesothelial Stromal Cells Support Hematopoiesis and Differentiate into Osteogenic and Adipogenic Cell Lineages.

The peritoneum is a thin membrane that covers most of the abdominal organs, composed of a monolayer of mesothelial cells and subjacent submesothelial loose connective tissue. Cells from the peritoneal wall are correlated with peritoneal fibrosis and epithelial-to-mesenchymal transition. However, the distinct involvement of mesothelial or submesothelial cells in such phenomena is still not clear. Here, we propose a new strategy to obtain stromal cells from anterior peritoneal wall explant cultures. These cells migrated from peritoneal tissues and proliferated in vitro for 4 weeks as adherent fibroblast-like cells. Optical and electronic microscopy analyses of the fragments revealed a significant submesothelial disorganization. The obtained cells were characterized as cytokeratin- vimentin+ laminin+ α-smooth muscle actin+, suggesting a connective tissue origin. Moreover, at the third passage, these stromal cells were CD90+CD73+CD29+Flk-1+CD45-, a phenotype normally attributed to cells of mesenchymal origin. These cells were able to support hematopoiesis, expressing genes involved in myelopoiesis (SCF, G-CSF, GM-CSF, IL-7 and CXCL-12), and differentiated into osteogenic and adipogenic cell lineages. The methodology demonstrated in this work can be considered an excellent experimental model to understand the physiology of the peritoneal wall in healthy and pathological processes. Moreover, this work shows for the first time that submesothelial stromal cells have properties similar to those of mesenchymal cells from other origins.

Recurrence Rate of Early Hepatitis C Virus Infection After Renal Transplantation Following Successful Treatment of Patients on Dialysis With Direct-Acting Antiviral Agents.

OBJECTIVES: Recurrence of hepatitis C virus after organ transplant has dreadful complications. An excellent response has been shown with direct-acting antiviral agents in transplant recipients. Although a sustained virological response is considered as the virological cure, it requires patients to be on dialysis for 3 months more before undergoing renal transplant, thus increasing the risk of hepatitis C virus reinfection and associated complications. We aimed to determine hepatitis C virus recurrence in renal transplant recipients who had achieved endof-treatment response before transplant. MATERIALS AND METHODS: Per our institutional dialysis protocol, patients who do not achieve rapid virological response are treated with 6 months of direct-acting antiviral agents. All patients who achieve end-of-treatment response are then referred for renal transplant. Our study included kidney transplant recipients who were treated with directacting antiviral agents and had a hepatitis C virus polymerase chain reaction test 3 months after renal transplant. We obtained demographic and clinical data of patients and used SPSS version 20.0 for statistical analyses. RESULTS: Our study included 48 transplant recipients; most were males (81.1%) with mean age of 28.7 ± 9.4 years. All patients received sofosbuvir, daclatasvir, and ribavirin combination before transplant. Most patients (70%) received treatment for 3 months. The polymerase chain reaction test for hepatitis C virus was conducted after a mean of 8.3 ± 3.3 months posttransplant. Laboratory parameters showed total bilirubin of 3.6 ± 17.5 mg/day, alanine aminotransferase of 51.5 ± 80.2 IU/L, and gammaglutamyltransferase of 133.9 ± 220 IU/L. Two recipients (4.2%) had posttransplant recurrence of hepatitis C virus infection. CONCLUSIONS: To our knowledge, this study is the first to document excellent response of direct-acting antivirals in renal transplant recipients who had been referred early for transplant. Thus, dialysis patients can undergo transplant after achieving end-oftreatment response.

Etiologies Associated With Elevated Liver Enzymes After Renal Transplant.

OBJECTIVES: One of the most important causes of morbidity and mortality in renal transplant recipients is liver disease. Liver dysfunction is shown in 7% to 67% of kidney transplant recipients. Liver insufficiency accounts for death in up to 28% of kidney transplant recipients. We stratified various etiological factors responsible for elevated liver enzymes in kidney transplant recipients. MATERIALS AND METHODS: We enrolled all patients who fulfilled inclusion criteria. The principal investigator obtained and recorded demographic and clinical information via a standardized form. We reviewed clinical records of kidney recipients with hepatotoxicity during the course of illness, and we analyzed data with SPSS statistical software (version 22). Descriptive statistics were used for continuous and categorical variables. RESULTS: All recipients of living related renal transplants from January 2015 to December 2016 were included in the study (n = 496). We excluded 64 patients with positive serology for hepatitis B or hepatitis C before transplant. Of the remaining 432 patients, 74 (17.1%) had deranged liver enzymes. Forty-one patients (55.4%) had deranged liver enzymes 3 to 4 years after transplant, whereas 23 patients (31.1%) had deranged liver enzymes 4 years after transplant. Liver parenchymal biopsy was performed in 17 patients (23%) to evaluate the etiology. The most common cause of deranged liver enzymes was sepsis, which was seen in 21 patients (28.4%), followed by viral hepatitis, ie, cytomegalovirus hepatitis in 7 (9.5%) and hepatitis C in 6 (8.1%) patients. Other causes included antituberculosis treatment-induced liver injury, autoimmune hepatitis, sinusoidal obstruction syndrome, and nonalcoholic steatohepatitis, observed in 4 patients each (5.4%). CONCLUSION: The most common cause of deranged liver enzymes in patients who received living related renal transplants in our population was sepsis, which can have a substantial effect on graft survival.

Management of Tacrolimus-Induced Toxicity With Normal Serum Levels After Liver Transplant.

Drug-induced liver injury after liver transplant occurs in 1.7% of patients. Tacrolimus is an effective immunosuppressant that is used to treat acute rejection. Although rare, it can cause toxicity, which is demonstrated by cholestatic liver injury. Here, we present a case of a young male patient who was diagnosed with Wilson disease, had penicillaminechelating therapy, and underwent living related liver transplant. Within 1 month posttransplant, he developed deranged, predominantly cholestatic pattern liver function tests. Laboratory parameters showed total bilirubin of 1.12 mg/ dL, alanine aminotransferase of 553 IU/L, gammaglutamyltransferase of 624 IU/L, and tacrolimus level of 10.2 ng/mL. After thorough evaluation, a liver biopsy was performed. Liver biopsy showed hepatocellular necrosis with centrilobular cholestasis without any evidence of graft rejection. However, with normal level of tacrolimus, the biopsy was suggestive of drug-induced liver injury. Thus, tacrolimus dose was reduced, resulting in improved liver function tests and patient discharge from the hospital. Tacrolimus is an effective immunosuppressant after liver transplant and has the ability to treat early acute rejection. The patient's liver biopsy showed hepatocellular necrosis with centrilobular cholestasis without any evidence of graft rejection. Cholestatic liver injury after tacrolimus usually resolves after dose reduction or by switching to another agent. With demonstrated tacrolimus-induced toxicity in liver transplant recipients, despite normal serum levels, transplant physicians should keep high index of suspicion regarding toxicity in the posttransplant setting.

[A peculiar lead poisoning: a concern of team achievement]. / Un caso di intossicazione anomala da piombo: l'importanza di un'intervento multidisciplinare.

We describe a case of lead poisoning in a worker after hand and forearm trauma with fracture of radius and multiple fractures of metacarpal bones and hand phalanges and tissue infiltration of lead oxide (PbO) paste. Orthopedic surgery was immediately performed. After 20 days the patient had abdominal colic pain episodes and severe stipsis and blood lead level (BLL) was 60 mcg/mL with urinary lead level (ULL) of 238 mcg/24 h. After mobilization test with calcium disodium edetate were observed a high increase of BLL (180 mcg/dL) and UBL (17,000 mcg/24h). An initial anemia was observed and became severe (Hb 7.6 g/dL). A NMR exam and echography showed forearm subcutaneous lead paste infiltration and the patient underwent to a second surgical debridement with local low temperature (5 degrees C) irrigation of saline and CaNa2EDTA made the removal of the hardened lead paste. The day after, oral succimer (DMSA) chelation treatment was started with recovery of lead poison.

Revolution in the diagnosis and management of hepatitis C virus infection in current era.

Chronic hepatitis C virus (HCV) infection is a major global public health problem, particularly in developing part of the world. Significant advances have been made in the early diagnosis and treatment of the disease. Its management has been particularly revolutionized during the past two decades. In this review, we summarize the major advances in the diagnostic and management armamentarium for chronic HCV infection. The focus of the present review is on the newer directly acting anti-viral agents, which have revolutionized the management of chronic HCV infection. Management of uncomplicated chronic HCV infection and of specific complications and special at-risk populations of patients will be covered in detail. Despite the advent and approval of highly effective and well tolerable oral agents, still many challenges remain, particularly the affordability, the equitable distribution and access to later drugs. The World Health Organization aims to eliminate viral hepatitis including HCV by 2030 since its poses a major public health threat. There is an urgent need to ensure uniform and early access to diagnostic and therapeutic facilities throughout the world if the later goal has to be realized.

Hepatic manifestations of coronavirus disease 2019 infection: Clinical and laboratory perspective.

The novel coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2, has become a global challenge of unprecedented nature since December 2019. Although most patients with COVID-19 exhibit mild clinical manifestations and upper respiratory tract involvement, in approximately 5%-10% of patients, the disease is severe and involves multiple organs, leading to multi-organ dysfunction and failure. The liver and gastrointestinal tract are also frequently involved in COVID-19. In the context of liver involvement in patients with COVID-19, many key aspects need to be addressed in both native and transplanted organs. This review focuses on the clinical presentations and laboratory abnormalities of liver function tests in patients with COVID-19 with no prior liver disease, patients with pre-existing liver diseases and liver transplant recipients. A brief overview of the history of COVID-19 and etiopathogenesis of the liver injury will also be described as a prelude to better understanding the above aspects.

Strengthening preparedness against global health threats: A paradigm shift based on One Health approaches.

The implementation of preparedness strategies to prevent and mitigate the impact of global health threats poses several challenges. It should promptly identify cross-cutting drivers of pandemic threats, assess context-specific risks, engage multiple stakeholders, and translate complex data from multiple sources into accessible information for action. This requires a coordinated, multidisciplinary and multisectoral effort engaging systems that, most of the time, work in isolation. The One Health (OH) approach promotes the collaboration and communication among different disciplines and sectors, and could be applied across the preparedness phases at national and international level. We discuss here gaps and needs in preparedness strategies, which can benefit from the OH approach, and a set of actionable recommendations, as shared with the G20-2021 with a dedicated Policy Brief. The discussion adds to the current debate about OH operationalization and promotes a paradigm shift towards coordinated prevention and preparedness strategies for early assessment and management of global health threats.

Cell cytoskeleton and tether extraction.

We perform a detailed investigation of the force × deformation curve in tether extraction from 3T3 cells by optical tweezers. Contrary to conventional wisdom about tethers extracted from cells, we find that actin filaments are present within them, so that a revised theory of tether pulling from cells is called for. We also measure steady and maximum tether force values significantly higher than previously published ones for 3T3 cells. Possible explanations for these differences are investigated. Further experimental support of the theory of force barriers for membrane tube extension is obtained. The potential of studies on tether pulling force × deformation for retrieving information on membrane-cytoskeleton interaction is emphasized.

The bone marrow compartment is modified in the absence of galectin-3.

Galectin-3 (gal-3) is a ß-galactoside binding protein present in multivalent complexes with an extracellular matrix and with cell surface glycoconjugates. In this context, it can deliver a variety of intracellular signals to modulate cell activation, differentiation and survival. In the hematopoietic system, it was demonstrated that gal-3 is expressed in myeloid cells and surrounding stromal cells. Furthermore, exogenous and surface gal-3 drive the proliferation of myeloblasts in a granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent manner. Here, we investigated whether gal-3 regulates the formation of myeloid bone marrow compartments by studying galectin-3(-/-) mice (gal-3(-/-)) in the C57BL/6 background. The bone marrow histology of gal-3(-/-) mice was significantly modified and the myeloid compartments drastically disturbed, in comparison with wild-type (WT) animals. In the absence of gal-3, we found reduced cell density and diaphyseal disorders containing increased trabecular projections into the marrow cavity. Moreover, myeloid cells presented limited capacity to differentiate into mature myeloid cell populations in gal-3(-/-) mice and the number of hematopoietic multipotent progenitors was increased relative to WT animals. In addition, bone marrow stromal cells of these mice had reduced levels of GM-CSF gene expression. Taken together, our data suggest that gal-3 interferes with hematopoiesis, controlling both precursors and stromal cells and favors terminal differentiation of myeloid progenitors rather than proliferation.

Ultrastructural and mineral phase characterization of the bone-like matrix assembled in F-OST osteoblast cultures.

Cell cultures are often used to study bone mineralization; however, not all systems achieve a bone-like matrix formation. In this study, the mineralized matrix assembled in F-OST osteoblast cultures was analyzed, with the aim of establishing a novel model for bone mineralization. The ultrastructure of the cultures was investigated using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy (TEM). The mineral phase was characterized using conventional and high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and solid-state (31)P and (1)H nuclear magnetic resonance. F-OST osteoblast cultures presented a clear nodular mineralization pattern. The chief features of the mineralizing nodules were globular accretions ranging from about 100 nm to 1.5 µm in diameter, loaded with needle-shaped crystallites. Accretions seemed to bud from the cell membrane, increase in size, and coalesce into larger ones. Arrays of loosely packed, randomly oriented collagen fibrils were seen along with the accretions. Mineralized fibrils were often observed, sometimes in close association with accretions. The mineral phase was characterized as a poorly crystalline hydroxyapatite. The Ca/P atomic ratio was 1.49 ± 0.06. The presence of OH was evident. The lattice parameters were a = 9.435 Å and c = 6.860 Å. The average crystallite size was 20 nm long and 10 nm wide. Carbonate substitutions were seen in phosphate and OH sites. Water was also found within the apatitic core. In conclusion, F-OST osteoblast cultures produce a bone-like matrix and may provide a good model for bone mineralization studies.

TRIB3 R84 variant affects glucose homeostasis by altering the interplay between insulin sensitivity and secretion.

AIMS/HYPOTHESIS: The results of studies on the genetics of complex traits need to be replicated and to reach robust statistical significance before they can be considered as established. We here tried to replicate the previously reported association between the TRIB3 Q84R polymorphism (rs2295490) and glucose homeostasis. METHODS: Three samples of Europeans with fasting glucose <7.0 mmol/l were studied. In sample 1 (n=791), the association between TRIB3 Q84R and impaired glucose regulation (IGR; defined as impaired fasting glucose and/or impaired glucose tolerance and/or type 2 diabetes by OGTT) and insulin sensitivity (ISI), and its interplay with early-phase insulin secretion (i.e. disposition index [DI]) were analysed. Sample 2 (n=374) and sample 3 (n=394) were used to replicate the association with IGR and insulin sensitivity (by glucose clamp), respectively. Genotyping was performed by TaqMan allele discrimination. RESULTS: R84 carriers were at higher risk of IGR: OR for the additive model 1.54, p=0.004, and 1.63, p=0.027, in samples 1 and 2, respectively. In sample 1, both ISI (p=0.005) and DI (p=0.043) were progressively lower from QQ to QR and RR individuals. A 'triangulation approach' indicated that the association with IGR was mostly mediated by DI rather than by ISI changes (i.e. being the expected ORs 1.51 and 1.25, respectively). In sample 3, glucose disposal was 38.8+/-17.7, 33.8+/-14.4, and 31.6+/-13.3 micromol min(-1)kg(-1), p=0.022, in QQ, QR and RR individuals, respectively. CONCLUSIONS/INTERPRETATION: Our data confirm that the TRIB3 R84 variant affects glucose homeostasis and suggest this effect is due to an alteration of the interplay between insulin sensitivity and secretion.

Positive and negative regulation of the composite octamer motif of the interleukin 2 enhancer by AP-1, Oct-2, and retinoic acid receptor.

The differentiating agent retinoic acid (RA) has been previously reported to interfere with 12-O-tetradecanoyl-phorbol-13-acetate (TPA)/Ca2+-induced signals for the regulation of the -96 to -66-bp octamer motif found in the enhancer for the interleukin (IL)-2 gene, which encodes a major T lymphocyte growth factor. The IL-2 octamer motif is a composite cis-element which binds Oct-1 and Oct-2 as well as a TPA/Ca2+-inducible nuclear factor, previously termed octamer-associated protein (OAP40). We show here that Oct-2, despite the presence of an active transcriptional activation domain, requires TPA/Ca2+-induced signals to strongly transactivate the IL-2 octamer motif in Jurkat T cells. This Oct-2-dependent transactivation is inhibited by RA. The presence of an intact COOH-terminal domain of Oct-2 contributes to both TPA/Ca2+-induced transactivation and the RA-mediated repression. We also show that both Fos and Jun components of the AP-1 factors participate in the OAP40 complex. Furthermore, transfected c-jun, jun-B, jun-D, c-fos, or Fos-B expression vectors partially substitute for TPA and Ca2+ and cooperate with Oct-2 for the transactivation of the combined OAP/octamer cis-element. Mutations of the genuine octamer-binding site abrogate both the binding of Oct-1 and Oct-2 and the TPA/Ca2+-induced transactivation of the OAP/octamer motif. OAP confers to Oct-2 responsivity to both TPA/Ca2+ and RA, since specific mutations of the AP-1/OAP-binding site significantly reduce the transactivation by Oct-2 in response to TPA and Ca2+ and abolish the inhibition by RA. Furthermore, retinoic acid receptor (RAR) alpha is able to inhibit in vitro the formation of the complex between the nuclear AP-1/OAP and its specific binding site, resulting in the interference with Oct-2-dependent cis-regulatory function of this AP-1 element. Therefore, we propose that the TPA/calcium-activated AP-1/OAP element is the main target of positive or negative regulatory signals influencing the IL-2 octamer motif, through synergism with Oct-2 and antagonism by RAR.