The universal suppressor mutation restores membrane budding defects in the HSV-1 nuclear egress complex by stabilizing the oligomeric lattice.

Nuclear egress is an essential process in herpesvirus replication whereby nascent capsids translocate from the nucleus to the cytoplasm. This initial step of nuclear egress-budding at the inner nuclear membrane-is coordinated by the nuclear egress complex (NEC). Composed of the viral proteins UL31 and UL34, NEC deforms the membrane around the capsid as the latter buds into the perinuclear space. NEC oligomerization into a hexagonal membrane-bound lattice is essential for budding because NEC mutants designed to perturb lattice interfaces reduce its budding ability. Previously, we identified an NEC suppressor mutation capable of restoring budding to a mutant with a weakened hexagonal lattice. Using an established in-vitro budding assay and HSV-1 infected cell experiments, we show that the suppressor mutation can restore budding to a broad range of budding-deficient NEC mutants thereby acting as a universal suppressor. Cryogenic electron tomography of the suppressor NEC mutant lattice revealed a hexagonal lattice reminiscent of wild-type NEC lattice instead of an alternative lattice. Further investigation using x-ray crystallography showed that the suppressor mutation promoted the formation of new contacts between the NEC hexamers that, ostensibly, stabilized the hexagonal lattice. This stabilization strategy is powerful enough to override the otherwise deleterious effects of mutations that destabilize the NEC lattice by different mechanisms, resulting in a functional NEC hexagonal lattice and restoration of membrane budding.

Structure and RAF family kinase isoform selectivity of type II RAF inhibitors tovorafenib and naporafenib.

Upon activation by RAS, RAF family kinases initiate signaling through the MAP kinase cascade to control cell growth, proliferation, and differentiation. Among RAF isoforms (ARAF, BRAF, and CRAF), oncogenic mutations are by far most frequent in BRAF. The BRAFV600E mutation drives more than half of all malignant melanoma and is also found in many other cancers. Selective inhibitors of BRAFV600E (vemurafenib, dabrafenib, encorafenib) are used clinically for these indications, but they are not effective inhibitors in the context of oncogenic RAS, which drives dimerization and activation of RAF, nor for malignancies driven by aberrantly dimerized truncation/fusion variants of BRAF. By contrast, a number of "type II" RAF inhibitors have been developed as potent inhibitors of RAF dimers. Here, we compare potency of type II inhibitors tovorafenib (TAK-580) and naporafenib (LHX254) in biochemical assays against the three RAF isoforms and describe crystal structures of both compounds in complex with BRAF. We find that tovorafenib and naporafenib are most potent against CRAF but markedly less potent against ARAF. Crystal structures of both compounds with BRAFV600E or WT BRAF reveal the details of their molecular interactions, including the expected type II-binding mode, with full occupancy of both subunits of the BRAF dimer. Our findings have important clinical ramifications. Type II RAF inhibitors are generally regarded as pan-RAF inhibitors, but our studies of these two agents, together with recent work with type II inhibitors belvarafenib and naporafenib, indicate that relative sparing of ARAF may be a property of multiple drugs of this class.

Well Put Together-A Guide to Accessorizing with the Herpesvirus gH/gL Complexes.

Herpesviruses are enveloped, double-stranded DNA viruses that infect a variety of hosts across the animal kingdom. Nine of these establish lifelong infections in humans, for which there are no cures and few vaccine or treatment options. Like all enveloped viruses, herpesviruses enter cells by fusing their lipid envelopes with a host cell membrane. Uniquely, herpesviruses distribute the functions of receptor engagement and membrane fusion across a diverse cast of glycoproteins. Two glycoprotein complexes are conserved throughout the three herpesvirus subfamilies: the trimeric gB that functions as a membrane fusogen and the heterodimeric gH/gL, the role of which is less clearly defined. Here, we highlight the conserved and divergent functions of gH/gL across the three subfamilies of human herpesviruses by comparing its interactions with a broad range of accessory viral proteins, host cell receptors, and neutralizing or inhibitory antibodies. We propose that the intrinsic structural plasticity of gH/gL enables it to function as a signal integration machine that can accept diverse regulatory inputs and convert them into a "trigger" signal that activates the fusogenic ability of gB.

Allosteric MEK inhibitors act on BRAF/MEK complexes to block MEK activation.

The RAF/MEK/ERK pathway is central to the control of cell physiology, and its dysregulation is associated with many cancers. Accordingly, the proteins constituting this pathway, including MEK1/2 (MEK), have been subject to intense drug discovery and development efforts. Allosteric MEK inhibitors (MEKi) exert complex effects on RAF/MEK/ERK pathway signaling and are employed clinically in combination with BRAF inhibitors in malignant melanoma. Although mechanisms and structures of MEKi bound to MEK have been described for many of these compounds, recent studies suggest that RAF/MEK complexes, rather than free MEK, should be evaluated as the target of MEKi. Here, we describe structural and biochemical studies of eight structurally diverse, clinical-stage MEKi to better understand their mechanism of action on BRAF/MEK complexes. We find that all of these agents bind in the MEK allosteric site in BRAF/MEK complexes, in which they stabilize the MEK activation loop in a conformation that is resistant to BRAF-mediated dual phosphorylation required for full activation of MEK. We also show that allosteric MEK inhibitors act most potently on BRAF/MEK complexes rather than on free active MEK, further supporting the notion that a BRAF/MEK complex is the physiologically relevant pharmacologic target for this class of compounds. Our findings provide a conceptual and structural framework for rational development of RAF-selective MEK inhibitors as an avenue to more effective and better-tolerated agents targeting this pathway.

Hipertensión Arterial Secundaria ¿por dónde empezar? / Secondary Arterial Hypertension, where to start?

30 to 40% of the adult population worldwide has been diagnosed with hypertension, among these patients 5 to 10% of them could have a possibly curable condition. In order to recognize this special population, the clinician must perform a complete work up and be aware of the main underlying causes of secondary hypertension. Often this could be a goal difficult to accomplish. The purpose of this article is to discuss the most frequent causes of secondary hypertension and offer a diagnostic approach for these patients. Clinicians should never forget that drug-related hypertension is a common cause that is discovered only with the help of a good medical history.

Inhibition of the proteasome preserves Mitofusin-2 and mitochondrial integrity, protecting cardiomyocytes during ischemia-reperfusion injury.

Cardiomyocyte loss is the main cause of myocardial dysfunction following an ischemia-reperfusion (IR) injury. Mitochondrial dysfunction and altered mitochondrial network dynamics play central roles in cardiomyocyte death. Proteasome inhibition is cardioprotective in the setting of IR; however, the mechanisms underlying this protection are not well-understood. Several proteins that regulate mitochondrial dynamics and energy metabolism, including Mitofusin-2 (Mfn2), are degraded by the proteasome. The aim of this study was to evaluate whether proteasome inhibition can protect cardiomyocytes from IR damage by maintaining Mfn2 levels and preserving mitochondrial network integrity. Using ex vivo Langendorff-perfused rat hearts and in vitro neonatal rat ventricular myocytes, we showed that the proteasome inhibitor MG132 reduced IR-induced cardiomyocyte death. Moreover, MG132 preserved mitochondrial mass, prevented mitochondrial network fragmentation, and abolished IR-induced reductions in Mfn2 levels in heart tissue and cultured cardiomyocytes. Interestingly, Mfn2 overexpression also prevented cardiomyocyte death. This effect was apparently specific to Mfn2, as overexpression of Miro1, another protein implicated in mitochondrial dynamics, did not confer the same protection. Our results suggest that proteasome inhibition protects cardiomyocytes from IR damage. This effect could be partly mediated by preservation of Mfn2 and therefore mitochondrial integrity.

Nombres populares y clasificación de las drogas de abuso ilícitas en Chile / Popular names and classification of illicit drugs commonly used in Chile

Background The consumption of illicit drugs in Chile has increased over the years generating abuse and dependence problems and becoming a public health problem. Aim To build and disseminate a figure in which health personnel can quickly visualize illicit drugs and their common names, and thus be able to associate them with the effects and risks that are expected in the patient. Material and Methods A bibliographic review and compilation of information obtained from dealers and drug abusers. Results A figure and a table were developed. The former illustrates the classification and common names of drugs, while the second indicates the mechanisms of action and effects expected in the body according to each drug of abuse. Conclusions Illicit drugs have several popular names and various mechanisms of action. When confronting drug consumption this information is crucial to provide an adequate treatment and withdrawal management. However, it is important to keep in mind that this work only represents a management guide and that treatment should always focus on the condition and clinical manifestations of the patient.

Architecture of autoinhibited and active BRAF-MEK1-14-3-3 complexes.

RAF family kinases are RAS-activated switches that initiate signalling through the MAP kinase cascade to control cellular proliferation, differentiation and survival1-3. RAF activity is tightly regulated and inappropriate activation is a frequent cause of cancer4-6; however, the structural basis for RAF regulation is poorly understood at present. Here we use cryo-electron microscopy to determine autoinhibited and active-state structures of full-length BRAF in complexes with MEK1 and a 14-3-3 dimer. The reconstruction reveals an inactive BRAF-MEK1 complex restrained in a cradle formed by the 14-3-3 dimer, which binds the phosphorylated S365 and S729 sites that flank the BRAF kinase domain. The BRAF cysteine-rich domain occupies a central position that stabilizes this assembly, but the adjacent RAS-binding domain is poorly ordered and peripheral. The 14-3-3 cradle maintains autoinhibition by sequestering the membrane-binding cysteine-rich domain and blocking dimerization of the BRAF kinase domain. In the active state, these inhibitory interactions are released and a single 14-3-3 dimer rearranges to bridge the C-terminal pS729 binding sites of two BRAFs, which drives the formation of an active, back-to-back BRAF dimer. Our structural snapshots provide a foundation for understanding normal RAF regulation and its mutational disruption in cancer and developmental syndromes.

Plasmaféresis, experiencia del Hospital Regional de Talca en pacientes con indicaciones nefrológicas / Plasmapheresis, experience of the Regional Hospital of Talca, in patients with nephrological indications

INTRODUCTION: Plasmapheresis is an extracorporeal procedure that allows the plasma to be separated from the figurative elements of the blood, removing specific elements involved in pathological processes. OBJECTIVE: To show the experience of the Regional Hospital of Talca (HRT) in the use of Plasmapheresis from 2017 to March 2019. METHODS: Corresponds to a retrospective study of all patients undergoing plasmapheresis from January 2017 to March 2019 (27 months). The clinical profile of this group of patients is analyzed, emphasizing in the nephrological etiologies and showing the clinical evolution of the diseases submitted to this procedure and aspects such as number of sessions, complications and associated therapies. RESULTS: In this period 14 patients have required plasmapheresis in our center, 9 cases for renal causes (64.2%) and 5 for non-renal causes (35.7%). A deceased was recorded during the acute stage of the disease (7.14%), in the context of a negative antineutrophil cytoplasmic antibody (ANCA) in patient with pulmonary-renal syndrome. 78% of those who needed plasmapheresis for renal etiologies are on hemodialysis at the end of the work. The clinical improvement experienced in the majority of the cases studied allows us to attribute a beneficial effect of plasmapheresis.

[Popular names and classification of illicit drugs commonly used in Chile]. / Nombres populares y clasificación de las drogas de abuso ilícitas en Chile.

Background The consumption of illicit drugs in Chile has increased over the years generating abuse and dependence problems and becoming a public health problem. Aim To build and disseminate a figure in which health personnel can quickly visualize illicit drugs and their common names, and thus be able to associate them with the effects and risks that are expected in the patient. Material and Methods A bibliographic review and compilation of information obtained from dealers and drug abusers. Results A figure and a table were developed. The former illustrates the classification and common names of drugs, while the second indicates the mechanisms of action and effects expected in the body according to each drug of abuse. Conclusions Illicit drugs have several popular names and various mechanisms of action. When confronting drug consumption this information is crucial to provide an adequate treatment and withdrawal management. However, it is important to keep in mind that this work only represents a management guide and that treatment should always focus on the condition and clinical manifestations of the patient.

Domain-dependent effects of insulin and IGF-1 receptors on signalling and gene expression.

Despite a high degree of homology, insulin receptor (IR) and IGF-1 receptor (IGF1R) mediate distinct cellular and physiological functions. Here, we demonstrate how domain differences between IR and IGF1R contribute to the distinct functions of these receptors using chimeric and site-mutated receptors. Receptors with the intracellular domain of IGF1R show increased activation of Shc and Gab-1 and more potent regulation of genes involved in proliferation, corresponding to their higher mitogenic activity. Conversely, receptors with the intracellular domain of IR display higher IRS-1 phosphorylation, stronger regulation of genes in metabolic pathways and more dramatic glycolytic responses to hormonal stimulation. Strikingly, replacement of leucine973 in the juxtamembrane region of IR to phenylalanine, which is present in IGF1R, mimics many of these signalling and gene expression responses. Overall, we show that the distinct activities of the closely related IR and IGF1R are mediated by their intracellular juxtamembrane region and substrate binding to this region.

Trasplante renal en el Hospital Regional de Talca / Renal transplantation at Hospital Regional, Talca

La mejor terapia para la insuficiencia renal crónica es el transplante renal. Para los pacientes de provincia esta alternativa está limitada por factores como la ruralidad y concentración de centros de trasplantes en Santiago. El presente trabajo muestra la experiencia inicial del Hospital Regional de Talca en transplante renal. Se evalúan los primeros 10 meses del programa que reúne los primeros 17 transplantados consecutivos. Estos se hicieron en 12 pacientes masculinos y 5 femeninos, con seguimiento promedio de 6 meses y una creatinina promedio de 1,4 mg por ciento. La mayor parte de los órganos son de origen local, con un tiempo de isquemia fría de 22,75 horas e isquemia caliente de 32 min. Este programa aunque de corta evolución demuestra que los hospitales en regionespueden hacer programas que no sean absolutamente dependiente de la obtención de órganos en los centros capitalinos. Los resultados funcionales junto con el 100 por ciento de sobrevida tanto de los pacientes como de los órganos son destacables, pero éstos deberán ser revaluados con mayor tiempo de evolución y mayor número de enfermos