The Bcl6-SMRT/NCoR cistrome represses inflammation to attenuate atherosclerosis

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Highlights? Bcl6 is a critical antiatherogenic regulator ? Inhibition of Bcl6-SMRT/NCoR interactions induces atherogenic gene expression ? SMRT and NCoR cistromes each exceed 30,000 sites, with a nearly 50% overlap ? Bcl6 recruits SMRT and NCoR to NF-κB-driven inflammatory and tissue remodeling genes     

Induction of superficial zone protein (SZP)/lubricin/PRG 4 in muscle-derived mesenchymal stem/progenitor cells by transforming growth factor-β1 and bone morphogenetic protein-7

Introduction

Articular cartilage (AC) is an avascular tissue with precise polarity and organization. The three distinct zones are: surface, middle and deep. The production and accumulation of the superficial zone protein (SZP), also known as lubricin, by the surface zone is a characteristic feature of AC. To date, there is a wealth of evidence showing differentiation of AC from mesenchymal stem cells. Most studies that described chondrogenic differentiation did not focus on AC with characteristic surface marker SZP/lubricin. The present investigation was initiated to determine the induction of SZP/lubricin in skeletal muscle-derived mesenchymal stem/progenitor cells (MDMSCs) by transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7).

Methods

MDMSCs were cultured as a monolayer at a density of 1 × 10⁵ cells/well in 12-well tissue culture plates. Cell cultures were treated for 3, 7 and 10 days with TGF-β1 and BMP-7. The medium was analyzed for SZP. The cells were used to isolate RNA for RT-PCR assays for SZP expression.

Results

The SZP/lubricin increased in a time-dependent manner on Days 3, 7 and 10 in the medium. As early as Day 3, there was a three-fold increase in response to 3 ng/ml of TGF-β1 and 300 ng/ml of BMP-7. This was confirmed by immunochemical localization of SZP as early as Day 3 after treatment with TGF-β1. The expression of SZP mRNA was enhanced by TGF-β1.

Conclusions

The present investigation demonstrated the efficient and reproducible induction of SZP/lubricin accumulation by TGF-β1 and BMP-7 in skeletal MDMSCs. Optimization of the experimental conditions may permit the utility of MDMSCs in generating surface zone-like cells with phenotypic markers of AC and, therefore, constitute a promising cell source for tissue engineering approaches of superficial zone cartilage.     

Cenancestor, the Last Universal Common Ancestor

Darwin suggested that all life on Earth could be phylogenetically related. Modern biology has confirmed Darwin??s extraordinary insight; the existence of a universal genetic code is just one of many evidences of our common ancestry. Based on the three domain phylogeny proposed by Woese and Fox in the early 1970s that all living beings can be classified on one of three main cellular lineages (Archaea, Bacteria, and Eukarya), it is possible to reconstruct some of the characteristics of the Last Universal Common Ancestor or cenancestor. Comparative genomics of organisms from the three domains has shown that the cenancestor was not a direct descendant of the prebiotic soup nor a primitive cellular entity where the genotype and the phenotype had an imprecise relationship (i.e., a progenote), rather it was an organism similar in complexity to extant cells. Due to the process of horizontal gene transfer and secondary gene losses, several questions regarding the nature of the cenancestor remain unsolved. However, attempts to infer its nature have led to the identification of a set of universally conserved genes. The research on the nature of the last universal common ancestor promises to shed light on fundamental aspects of living beings.     

Coenzymes, viruses and the RNA world

The results of a detailed bioinformatic search for ribonucleotidyl coenzyme biosynthetic sequences in DNA- and RNA viral genomes are presented. No RNA viral genome sequence available as of April 2011 appears to encode for sequences involved in coenzyme biosynthesis. In both single- and double-stranded DNA viruses a diverse array of coenzyme biosynthetic genes has been identified, but none of the viral genomes examined here encodes for a complete pathway. Although our conclusions may be constrained by the unexplored diversity of viral genomes and the biases in the construction of viral genome databases, our results do not support the possibility that RNA viruses are direct holdovers from an ancient RNA/protein world. Extrapolation of our results to evolutionary epochs prior to the emergence of DNA genomes suggest that during those early stages living entities may have depended on discontinuous genetic systems consisting of multiple small-size RNA sequences.     

Structural basis of specificity in tetrameric Kluyveromyces lactis β-galactosidase

β-Galactosidase or lactase is a very important enzyme in the food industry, being that from the yeast Kluyveromyces lactis the most widely used. Here we report its three-dimensional structure both in the free state and complexed with the product galactose. The monomer folds into five domains in a pattern conserved with the prokaryote enzymes of the GH2 family, although two long insertions in domains 2 and 3 are unique and related to oligomerization and specificity. The tetrameric enzyme is a dimer of dimers, with higher dissociation energy for the dimers than for its assembly. Two active centers are located at the interface within each dimer in a narrow channel. The insertion at domain 3 protrudes into this channel and makes putative links with the aglycone moiety of docked lactose. In spite of common structural features related to function, the determinants of the reaction mechanism proposed for Escherichia coli β-galactosidase are not found in the active site of the K. lactis enzyme. This is the first X-ray crystal structure for a β-galactosidase used in food processing.     

Catalytically impaired TrpA subunit of tryptophan synthase from Chlamydia trachomatis is an allosteric regulator of TrpB

Intracellular growth and pathogenesis of Chlamydia species is controlled by the availability of tryptophan, yet the complete biosynthetic pathway for l‐Trp is absent among members of the genus. Some representatives, however, preserve genes encoding tryptophan synthase, TrpAB – a bifunctional enzyme catalyzing the last two steps in l‐Trp synthesis. TrpA (subunit α) converts indole‐3‐glycerol phosphate into indole and glyceraldehyde‐3‐phosphate (α reaction). The former compound is subsequently used by TrpB (subunit β) to produce l‐Trp in the presence of l‐Ser and a pyridoxal 5′‐phosphate cofactor (β reaction). Previous studies have indicated that in Chlamydia, TrpA has lost its catalytic activity yet remains associated with TrpB to support the β reaction. Here, we provide detailed analysis of the TrpAB from C. trachomatis D/UW‐3/CX, confirming that accumulation of mutations in the active site of TrpA renders it enzymatically inactive, despite the conservation of the catalytic residues. We also show that TrpA remains a functional component of the TrpAB complex, increasing the activity of TrpB by four‐fold. The side chain of non‐conserved βArg267 functions as cation effector, potentially rendering the enzyme less susceptible to the solvent ion composition. The observed structural and functional changes detected herein were placed in a broader evolutionary and genomic context, allowing identification of these mutations in relation to their trp gene contexts in which they occur. Moreover, in agreement with the in vitro data, partial relaxation of purifying selection for TrpA, but not for TrpB, was detected, reinforcing a partial loss of TrpA functions during the course of evolution.     

Elevated levels of soluble ST2 protein in dengue virus infected patients

Levels of the soluble form of the interleukin-1 receptor-like 1 protein (IL-1RL-1/ST2) are elevated in the serum of patients with diseases characterized by an inflammatory response. The objective of this study was to determine the concentration of soluble ST2 (sST2) in dengue infected patients during the course of the disease. Twenty-four patients with confirmed dengue infection, classified as dengue fever, and 11 patients with other febrile illness (OFI) were evaluated. Levels of sST2 in serum and laboratory variables usually altered during dengue infections were measured. Dengue infected patients had higher serum sST2 levels than OFI at the end of the febrile stage and at defervescence (p=0.0088 and p=0.0004, respectively). Patients with secondary dengue infections had higher serum sST2 levels compared with patients with primary dengue infections (p=0.047 at last day of fever and p=0.030 at defervescence). Furthermore, in dengue infected patients, we found a significant negative correlation of sST2 with platelet and WBC counts, and positive correlation with thrombin time and transaminases activity. We suggest that sST2 could be a potential marker of dengue infection, could be associated with severity or could play a role in the immune response in secondary dengue virus infection.     

An unusual Xanthophyllomyces strain from leaves of Eucalyptus globulus in Chile

Xanthophyllomyces sp. was isolated as an epiphytic red yeast from leaves of Eucalyptus glo-bulus in Concepción, Chile. Sexual reproduction was by basidiospores produced from one or rarely two metabasidia arising from a yeast cell without preceding paedogamy. The main carotenoid pigment was astaxanthin. This isolate did not cluster with the X. dendrorhous complex (including Phaffia rhodozyma) in ITS and 26S rDNA-based phylogenetic analyses. The phylloplane may be a further habitat for Xanthophyllomyces, in addition to the well-known spring sap-flows of deciduous trees and the recently-characterised ascostromata of Cyttaria hariotii.     

Colocalized structural and functional changes in the cortex of patients with trigeminal neuropathic pain

Background

Recent data suggests that in chronic pain there are changes in gray matter consistent with decreased brain volume, indicating that the disease process may produce morphological changes in the brains of those affected. However, no study has evaluated cortical thickness in relation to specific functional changes in evoked pain. In this study we sought to investigate structural (gray matter thickness) and functional (blood oxygenation dependent level – BOLD) changes in cortical regions of precisely matched patients with chronic trigeminal neuropathic pain (TNP) affecting the right maxillary (V2) division of the trigeminal nerve. The model has a number of advantages including the evaluation of specific changes that can be mapped to known somatotopic anatomy.

Methodology/Principal Findings

Cortical regions were chosen based on sensory (Somatosensory cortex (SI and SII), motor (MI) and posterior insula), or emotional (DLPFC, Frontal, Anterior Insula, Cingulate) processing of pain. Both structural and functional (to brush-induced allodynia) scans were obtained and averaged from two different imaging sessions separated by 2–6 months in all patients. Age and gender-matched healthy controls were also scanned twice for cortical thickness measurement. Changes in cortical thickness of TNP patients were frequently colocalized and correlated with functional allodynic activations, and included both cortical thickening and thinning in sensorimotor regions, and predominantly thinning in emotional regions.

Conclusions

Overall, such patterns of cortical thickness suggest a dynamic functionally-driven plasticity of the brain. These structural changes, which correlated with the pain duration, age-at-onset, pain intensity and cortical activity, may be specific targets for evaluating therapeutic interventions.