Nef-mediated enhancement of cellular activation and human immunodeficiency virus type 1 replication in primary T cells is dependent on association with p21-activated kinase 2

<p>Abstract</p> <p>Background</p> <p>The HIV-1 accessory protein Nef is an important determinant of lentiviral pathogenicity that contributes to disease progression by enhancing viral replication and other poorly understood mechanisms. Nef mediates diverse functions including downmodulation of cell surface CD4 and MHC Class I, enhancement of viral infectivity, and enhancement of T cell activation. Nef interacts with a multiprotein signaling complex that includes Src family kinases, Vav1, CDC42, and activated PAK2 (p21-activated kinase 2). Although previous studies have attempted to identify a biological role for the Nef-PAK2 signaling complex, the importance of this complex and its constituent proteins in Nef function remains unclear.</p> <p>Results</p> <p>Here, we show that Nef mutants defective for PAK2-association, but functional for CD4 and MHC Class I downmodulation and infectivity enhancement, are also defective for the ability to enhance viral replication in primary T cells that are infected and subsequently activated by sub-maximal stimuli (1 μg/ml PHA-P). In contrast, these Nef mutants had little or no effect on HIV-1 replication in T cells activated by stronger stimuli (2 μg/ml PHA-P or anti-CD3/CD28-coated beads). Viruses bearing wild-type Nefs, but not Nef mutants defective for PAK2 association, enhanced NFAT and IL2 receptor promoter activity in Jurkat cells. Moreover, expression of wild-type Nefs, but not mutant Nefs defective for PAK2 association, was sufficient to enhance responsiveness of primary CD4 and CD8 T cells to activating stimuli in Nef-expressing and bystander cells. siRNA knockdown of PAK2 in Jurkat cells reduced NFAT activation induced by anti-CD3/CD28 stimulation both in the presence and absence of Nef, and expression of a PAK2 dominant mutant inhibited Nef-mediated enhancement of CD25 expression.</p> <p>Conclusion</p> <p>Nef-mediated enhancement of cellular activation and viral replication in primary T cells is dependent on PAK2 and on the strength of the activating stimuli, and correlates with the ability of Nef to associate with PAK2. PAK2 is likely to play a role in Nef-mediated enhancement of viral replication and immune activation <it>in vivo</it>.</p

Una propuesta por competencias para el proceso de inducción y formación de equipos de alto desempeño en los Proyectos de Aplicación Profesional de ITESO. El caso del PAP Consultoría en Mype del Centro Universidad Empresa

Este documento recapitula la experiencia del rediseño del curso de inducción que se imparte a los estudiantes del Proyecto de Aplicación Profesional Consultoría a Mype coordinado por el Centro Universidad Empresa (CUE) de ITESO. Dicho proyecto (PAP) tiene como función principal el dar consultoría integral con un enfoque sistémico a varias empresas por semestre. En este documento se dan a conocer las competencias que se promueven en dicho curso, así como el método de armado de equipos de alto desempeño para el proyecto de aplicación profesional

Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation

<p>Abstract</p> <p>Background</p> <p>HIV-1 Nef protein contributes to pathogenesis via multiple functions that include enhancement of viral replication and infectivity, alteration of intracellular trafficking, and modulation of cellular signaling pathways. Nef stimulates formation of tunneling nanotubes and virological synapses, and is transferred to bystander cells via these intercellular contacts and secreted microvesicles. Nef associates with and activates Pak2, a kinase that regulates T-cell signaling and actin cytoskeleton dynamics, but how Nef promotes nanotube formation is unknown.</p> <p>Results</p> <p>To identify Nef binding partners involved in Pak2-association dependent Nef functions, we employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A75P in NL4-3). We report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6), an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation. Additionally, Pak2 kinase was associated exclusively with wild-type Nef. Association of EXOC1, EXOC2, EXOC3, and EXOC4 with wild-type, but not mutant Nef, was verified by co-immunoprecipitation assays in Jurkat cells. Furthermore, shRNA-mediated depletion of EXOC2 in Jurkat cells abrogated Nef-mediated enhancement of nanotube formation. Using bioinformatic tools, we visualized protein interaction networks that reveal functional linkages between Nef, the exocyst complex, and the cellular endocytic and exocytic trafficking machinery.</p> <p>Conclusions</p> <p>Exocyst complex proteins are likely a key effector of Nef-mediated enhancement of nanotube formation, and possibly microvesicle secretion. Linkages revealed between Nef and the exocyst complex suggest a new paradigm of exocyst involvement in polarized targeting for intercellular transfer of viral proteins and viruses.</p

Acetarsol Suppositories: Effective Treatment for Refractory Proctitis in a Cohort of Patients with Inflammatory Bowel Disease.

BACKGROUND: Management of proctitis refractory to conventional therapies presents a common clinical problem. The use of acetarsol suppositories, which are derived from organic arsenic, was first described in 1965. Data concerning clinical efficacy and tolerability are very limited. AIM: To examine the efficacy of acetarsol suppositories for the treatment of refractory proctitis. METHODS: A retrospective analysis was performed on patients with inflammatory bowel disease treated with acetarsol suppositories between 2008 and 2014 at Addenbrooke's Hospital, Cambridge, United Kingdom. Clinical response was defined as resolution of symptoms back to baseline at the time of next clinic review. RESULTS: Thirty-nine patients were prescribed acetarsol suppositories between March 2008 and July 2014 (29 patients with ulcerative colitis, nine with Crohn's disease, and one with indeterminate colitis). Thirty-eight were included for analysis. The standard dose of acetarsol was 250 mg twice daily per rectum for 4 weeks. Clinical response was observed in 26 patients (68%). Of the 11 patients who had endoscopic assessment before and after treatment, nine (82%) showed endoscopic improvement and five (45%) were in complete remission (Wilcoxon signed-rank test p = 0.006). One patient developed a macular skin rash 1 week after commencing acetarsol, which resolved within 4 weeks of drug cessation. CONCLUSION: Acetarsol was effective for two out of every three patients with refractory proctitis. This cohort had failed a broad range of topical and systemic treatments, including anti-TNFα therapy. Clinical efficacy was reflected in significant endoscopic improvement. Adverse effects of acetarsol were rare

Magnetism and magnetocaloric properties of Co1−x_{1-x}Mnx_xCr2_2O4_4

Co$_{1-x}$Mn$_x$Cr$_2$O$_4$ crystallizes as a normal spinel in the cubic $Fd \overline{3}m$ space group, and the end members have been reported to display a region of collinear ferrimagnetism as well as a low-temperature spin-spiral state with variable coherence lengths from 3 nm to 10 nm in polycrystalline samples. Here, we present the synthesis of the entire solid solution, and data showing that the ferrimagnetic ordering temperature as well as the spin-spiral lock-in temperature are tunable with the Co/Mn ratio. The peak magnetocaloric entropy change was determined to be $\Delta S_M$ = -5.63 J kg$^{-1}$ K$^{-1}$ in an applied magnetic field change of $\Delta H$ = 0 T to 5 T for the Mn end-member at the ferrimagnetic ordering temperature. Using density functional theory (DFT), we explore the shortcomings of the magnetic deformation proxy to identify trends in $\Delta S_M$ across composition in this spinel system, and explore future extensions of theory to address these discrepancies

Nucleotomía percutánea automatizada: experiencia en 425 casos

En el presente trabajo exponemos nuestra experiencia en el tratamiento de la hernia discal lumbar mediante Nucleotomía Percutánea Automatizada. El estudio comprende el periodo de Junio de 1988 a Diciembre de 1992. Se incluyen un total de 425 enfermos de edades comprendidas entre los 18 y 58 años. Los pacientes han sido evaluados a las 6 semanas, a los 3 y a los 6 meses tras la intervención. Los resultados han sido satisfactorios en el 71% de los casos. Solamente hubo una complicación de espondilodiscitis. En el 29% de los casos se obtuvieron malos resultados. Un porcentaje importante de los fracasos, se debieron a una mala selección de los pacientes desde el punto de vista de su perfil psicológico.Our experience using automated percutaneous nucleotomy for treatment for herniated disc is presented. A total of 42 5 patientes, aged between 18 and 58 years and operated from June 88 to December 1992, has been included. Patients were clinically assessed at 6 weeks, 3 months and 6 months after surgery. Satisfactory results were found in 71% of cases. As for complications, there was only a case of discitis. In 29% of patients, the outcome was poor. An important group of failures were due to bad selection of patients regadings psychological profile