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On page 99 showing 1961 ~ 1980 papers out of 56,254 papers

Evaluation of functional erythropoietin receptor status in skeletal muscle in vivo: acute and prolonged studies in healthy human subjects.

  • Britt Christensen‎ et al.
  • PloS one‎
  • 2012‎

Erythropoietin receptors have been identified in human skeletal muscle tissue, but downstream signal transduction has not been investigated. We therefore studied in vivo effects of systemic erythropoietin exposure in human skeletal muscle.


Functional complexity of the axonal growth cone: a proteomic analysis.

  • Adriana Estrada-Bernal‎ et al.
  • PloS one‎
  • 2012‎

The growth cone, the tip of the emerging neurite, plays a crucial role in establishing the wiring of the developing nervous system. We performed an extensive proteomic analysis of axonal growth cones isolated from the brains of fetal Sprague-Dawley rats. Approximately 2000 proteins were identified at ≥ 99% confidence level. Using informatics, including functional annotation cluster and KEGG pathway analysis, we found great diversity of proteins involved in axonal pathfinding, cytoskeletal remodeling, vesicular traffic and carbohydrate metabolism, as expected. We also found a large and complex array of proteins involved in translation, protein folding, posttranslational processing, and proteasome/ubiquitination-dependent degradation. Immunofluorescence studies performed on hippocampal neurons in culture confirmed the presence in the axonal growth cone of proteins representative of these processes. These analyses also provide evidence for rough endoplasmic reticulum and reveal a reticular structure equipped with Golgi-like functions in the axonal growth cone. Furthermore, Western blot revealed the growth cone enrichment, relative to fetal brain homogenate, of some of the proteins involved in protein synthesis, folding and catabolism. Our study provides a resource for further research and amplifies the relatively recently developed concept that the axonal growth cone is equipped with proteins capable of performing a highly diverse range of functions.


Shear stress modulation of IL-1β-induced E-selectin expression in human endothelial cells.

  • Ryan B Huang‎ et al.
  • PloS one‎
  • 2012‎

Endothelial cells (ECs) are continuously exposed to hemodynamic forces imparted by blood flow. While it is known that endothelial behavior can be influenced by cytokine activation or fluid shear, the combined effects of these two independent agonists have yet to be fully elucidated.


Loss of proliferation and antigen presentation activity following internalization of polydispersed carbon nanotubes by primary lung epithelial cells.

  • Mandavi Kumari‎ et al.
  • PloS one‎
  • 2012‎

Interactions between poly-dispersed acid functionalized single walled carbon nanotubes (AF-SWCNTs) and primary lung epithelial (PLE) cells were studied. Peritoneal macrophages (PMs, known phagocytic cells) were used as positive controls in this study. Recovery of live cells from cultures of PLE cells and PMs was significantly reduced in the presence of AF-SWCNTs, in a time and dose dependent manner. Both PLE cells as well as PMs could take up fluorescence tagged AF-SWCNTs in a time dependent manner and this uptake was significantly blocked by cytochalasin D, an agent that blocks the activity of acto-myosin fibers and therefore the phagocytic activity of cells. Confocal microscopic studies confirmed that AF-SWCNTs were internalized by both PLE cells and PMs. Intra-trachially instilled AF-SWCNTs could also be taken up by lung epithelial cells as well as alveolar macrophages. Freshly isolated PLE cells had significant cell division activity and cell cycling studies indicated that treatment with AF-SWCNTs resulted in a marked reduction in S-phase of the cell cycle. In a previously standardized system to study BCG antigen presentation by PLE cells and PMs to sensitized T helper cells, AF-SWCNTs could significantly lower the antigen presentation ability of both cell types. These results show that mouse primary lung epithelial cells can efficiently internalize AF-SWCNTs and the uptake of nanotubes interfered with biological functions of PLE cells including their ability to present BCG antigens to sensitized T helper cells.


Functional desaturase Fads1 (Δ5) and Fads2 (Δ6) orthologues evolved before the origin of jawed vertebrates.

  • Luís Filipe Costa Castro‎ et al.
  • PloS one‎
  • 2012‎

Long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic (ARA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are essential components of biomembranes, particularly in neural tissues. Endogenous synthesis of ARA, EPA and DHA occurs from precursor dietary essential fatty acids such as linoleic and α-linolenic acid through elongation and Δ5 and Δ6 desaturations. With respect to desaturation activities some noteworthy differences have been noted in vertebrate classes. In mammals, the Δ5 activity is allocated to the Fads1 gene, while Fads2 is a Δ6 desaturase. In contrast, teleosts show distinct combinations of desaturase activities (e.g. bifunctional or separate Δ5 and Δ6 desaturases) apparently allocated to Fads2-type genes. To determine the timing of Fads1-Δ5 and Fads2-Δ6 evolution in vertebrates we used a combination of comparative and functional genomics with the analysis of key phylogenetic species. Our data show that Fads1 and Fads2 genes with Δ5 and Δ6 activities respectively, evolved before gnathostome radiation, since the catshark Scyliorhinus canicula has functional orthologues of both gene families. Consequently, the loss of Fads1 in teleosts is a secondary episode, while the existence of Δ5 activities in the same group most likely occurred through independent mutations into Fads2 type genes. Unexpectedly, we also establish that events of Fads1 gene expansion have taken place in birds and reptiles. Finally, a fourth Fads gene (Fads4) was found with an exclusive occurrence in mammalian genomes. Our findings enlighten the history of a crucially important gene family in vertebrate fatty acid metabolism and physiology and provide an explanation of how observed lineage-specific gene duplications, losses and diversifications might be linked to habitat-specific food web structures in different environments and over geological timescales.


Probing the behaviors of gold nanorods in metastatic breast cancer cells based on UV-vis-NIR absorption spectroscopy.

  • Weiqi Zhang‎ et al.
  • PloS one‎
  • 2012‎

In this work, behaviors of positively-charged AuNRs in a highly metastatic tumor cell line MDA-MB-231 are examined based on UV-vis-NIR absorption spectroscopy in combination with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and dark-field microscopic observation. It is found that characteristic surface plasmon resonance (SPR) peaks of AuNRs can be detected using spectroscopic method within living cells that have taken up AuNRs. The peak area of transverse SPR band is shown to be proportionally related to the amount of AuNRs in the cells determined with ICP-MS, which suggests a facile and real time quantification method for AuNRs in living cells. The shape of longitudinal SPR band in UV-vis-NIR spectrum reflects the aggregation state of AuNRs in the cells during the incubation period, which is proved by TEM and microscopic observations. Experimental results reveal that AuNRs are internalized by the cells rapidly; the accumulation, distribution and aggregation of AuNRs in the cells compartments are time and dose dependent. The established spectroscopic analysis method can not only monitor the behaviors of AuNRs in living cells but may also be helpful in choosing the optimum laser stimulation wavelength for anti-tumor thermotherapy.


Grape-derived polyphenols improve aging-related endothelial dysfunction in rat mesenteric artery: role of oxidative stress and the angiotensin system.

  • Noureddine Idris Khodja‎ et al.
  • PloS one‎
  • 2012‎

Aging is characterized by the development of an endothelial dysfunction, which affects both the nitric oxide (NO)- and the endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxations, associated with vascular oxidative stress and the activation of the angiotensin system. This study investigated whether red wine polyphenols (RWPs), antioxidants and potent stimulators of NO- and EDHF-mediated relaxations improve aging-related endothelial dysfunction, and, if so, examined the underlying mechanism. Mesenteric artery reactivity was determined in organ chambers, vascular oxidative stress by dihydroethidine and MitoSOX staining, and expression of target proteins by immunohistochemical staining. Control young rats (16 weeks) received solvent (ethanol, 3% v/v), and middle-aged rats (46 weeks) either solvent or RWPs (100 mg/kg/day) in the drinking water. The acetylcholine-induced endothelium-dependent NO component was slightly reduced whereas the EDHF component was markedly blunted in rings of middle-aged rats compared to young rats. The endothelial dysfunction was associated with oxidative stress, an upregulation of angiotensin II and AT1 receptors and a down-regulation of SK(Ca), IK(Ca), and angiotensin converting enzyme. Intake of RWPs for either one or two weeks improved the NO and the EDHF components of the relaxation, and normalized oxidative stress, the expression of SK(Ca), IK(Ca) and the components of the angiotensin system. The protective effect of the 2-week RWPs treatment persisted for one and two weeks following stopping intake of RWPs. Thus, intake of RWPs caused a persistent improvement of the endothelial function, particularly the EDHF component, in middle-aged rats and this effect seems to involve the normalization of the expression of SK(Ca), IK(Ca) and the angiotensin system.


Organizational heterogeneity of vertebrate genomes.

  • Svetlana Frenkel‎ et al.
  • PloS one‎
  • 2012‎

Genomes of higher eukaryotes are mosaics of segments with various structural, functional, and evolutionary properties. The availability of whole-genome sequences allows the investigation of their structure as "texts" using different statistical and computational methods. One such method, referred to as Compositional Spectra (CS) analysis, is based on scoring the occurrences of fixed-length oligonucleotides (k-mers) in the target DNA sequence. CS analysis allows generating species- or region-specific characteristics of the genome, regardless of their length and the presence of coding DNA. In this study, we consider the heterogeneity of vertebrate genomes as a joint effect of regional variation in sequence organization superimposed on the differences in nucleotide composition. We estimated compositional and organizational heterogeneity of genome and chromosome sequences separately and found that both heterogeneity types vary widely among genomes as well as among chromosomes in all investigated taxonomic groups. The high correspondence of heterogeneity scores obtained on three genome fractions, coding, repetitive, and the remaining part of the noncoding DNA (the genome dark matter--GDM) allows the assumption that CS-heterogeneity may have functional relevance to genome regulation. Of special interest for such interpretation is the fact that natural GDM sequences display the highest deviation from the corresponding reshuffled sequences.


A survey of genomic studies supports association of circadian clock genes with bipolar disorder spectrum illnesses and lithium response.

  • Michael J McCarthy‎ et al.
  • PloS one‎
  • 2012‎

Circadian rhythm abnormalities in bipolar disorder (BD) have led to a search for genetic abnormalities in circadian "clock genes" associated with BD. However, no significant clock gene findings have emerged from genome-wide association studies (GWAS). At least three factors could account for this discrepancy: complex traits are polygenic, the organization of the clock is more complex than previously recognized, and/or genetic risk for BD may be shared across multiple illnesses. To investigate these issues, we considered the clock gene network at three levels: essential "core" clock genes, upstream circadian clock modulators, and downstream clock controlled genes. Using relaxed thresholds for GWAS statistical significance, we determined the rates of clock vs. control genetic associations with BD, and four additional illnesses that share clinical features and/or genetic risk with BD (major depression, schizophrenia, attention deficit/hyperactivity). Then we compared the results to a set of lithium-responsive genes. Associations with BD-spectrum illnesses and lithium-responsiveness were both enriched among core clock genes but not among upstream clock modulators. Associations with BD-spectrum illnesses and lithium-responsiveness were also enriched among pervasively rhythmic clock-controlled genes but not among genes that were less pervasively rhythmic or non-rhythmic. Our analysis reveals previously unrecognized associations between clock genes and BD-spectrum illnesses, partly reconciling previously discordant results from past GWAS and candidate gene studies.


Arsenic trioxide exerts antimyeloma effects by inhibiting activity in the cytoplasmic substrates of histone deacetylase 6.

  • Xiaoyan Qu‎ et al.
  • PloS one‎
  • 2012‎

Arsenic trioxide (As(2)O(3)) has shown remarkable efficacy for the treatment of multiple myeloma (MM). Histone deacetylases (HDAC) play an important role in the control of gene expression, and their dysregulation has been linked to myeloma. Especially, HDAC6, a unique cytoplasmic member of class II, which mainly functions as α-tubulin deacetylase and Hsp90 deacetylase, has become a target for drug development to treat cancer due to its major contribution in oncogenic cell transformation. However, the mechanisms of action for As(2)O(3) have not yet been defined. In this study, we investigated the effect of As(2)O(3) on proliferation and apoptosis in human myeloma cell line and primary myeloma cells, and then we studied that As(2)O(3) exerts antimyeloma effects by inhibiting activity in the α-tubulin and Hsp90 through western blot analysis and immunoprecipitation. We found that As(2)O(3) acts directly on MM cells at relatively low concentrations of 0.5~2.5 µM, which effects survival and apoptosis of MM cells. However, As(2)O(3) inhibited HDAC activity at the relatively high concentration and dose-dependent manner (great than 4 µM). Subsequently, we found that As(2)O(3) treatment in a dose- and time-dependent fashion markedly increased the level of acetylated α-tubulin and acetylated Hsp90, and inhibited the chaperone association with IKKα activities and increased degradation of IKKα. Importantly, the loss of IKKα-associated Hsp90 occurred prior to any detectable loss in the levels of IKKα, indicating a novel pathway by which As(2)O(3) down-regulates HDAC6 to destabilize IKKα protein via Hsp90 chaperone function. Furthermore, we observed the effect of As(2)O(3) on TNF-α-induced NF-κB signaling pathway was to significantly reduced phosphorylation of Ser-536 on NF-κB p65. Therefore, our studies provide an important insight into the molecular mechanism of anti-myeloma activity of As(2)O(3) in HDAC6-Hsp90-IKKα-NFκB signaling axis and the rationale for As(2)O(3) can be extended readily using all the HDAC associated diseases.


NCAM180 regulates Ric8A membrane localization and potentiates β-adrenergic response.

  • Marie-Claude Amoureux‎ et al.
  • PloS one‎
  • 2012‎

Cooperation between receptors allows integrated intracellular signaling leading to appropriate physiological responses. The Neural Cell Adhesion Molecule (NCAM) has three main isoforms of 120, 140 and 180 kDa, with adhesive and signaling properties, but their respective functions remains to be fully identified. Here we show that the human NCAM180 intracellular domain is a novel interactor of the human guanosine exchange factor (GEF) Ric8A using the yeast two hybrid system and immunoprecipitation. Furthermore, NCAM, Ric8A and G(αs) form a tripartite complex. Colocalization experiments by confocal microscopy revealed that human NCAM180 specifically induces the recruitment of Ric8A to the membrane. In addition, using an in vitro recombinant system, and in vivo by comparing NCAM knock-out mouse brain to NCAM heterozygous and wild type brains, we show that NCAM expression dose dependently regulates Ric8A redistribution in detergent resistent membrane microdomains (DRM). Previous studies have demonstrated essential roles for Ric8 in G(α) protein activity at G protein coupled receptors (GPCR), during neurotransmitter release and for asymmetric cell division. We observed that inhibition of Ric8A by siRNA or its overexpression, decreases or increases respectively, cAMP production following β-adrenergic receptor stimulation. Furthermore, in human HEK293T recombinant cells, NCAM180 potentiates the G(αs) coupled β-adrenergic receptor response, in a Ric8A dependent manner, whereas NCAM120 or NCAM140 do not. Finally, in mouse hippocampal neurons expressing endogenously NCAM, NCAM is required for the agonist isoproterenol to induce cAMP production, and this requirement depends on Ric8A. These data illustrate a functional crosstalk between a GPCR and an IgCAM in the nervous system.


Effect of the citrus lycopene β-cyclase transgene on carotenoid metabolism in transgenic tomato fruits.

  • Fei Guo‎ et al.
  • PloS one‎
  • 2012‎

Lycopene β-cyclase (LYCB) is the key enzyme for the synthesis of β-carotene, a valuable component of the human diet. In this study, tomato constitutively express Lycb-1 was engineered. The β-carotene level of transformant increased 4.1 fold, and the total carotenoid content increased by 30% in the fruits. In the transgenic line, the downstream α-branch metabolic fluxes were repressed during the three developmental stages while α-carotene content increased in the ripe stage. Microarray analysis in the ripe stage revealed that the constitutive expression of Lycb-1 affected a number of pathways including the synthesis of fatty acids, flavonoids and phenylpropanoids, the degradation of limonene and pinene, starch and sucrose metabolism and photosynthesis. This study provided insight into the regulatory effect of Lycb-1 gene on plant carotenoid metabolism and fruit transcriptome.


Primitive duplicate Hox clusters in the European eel's genome.

  • Christiaan V Henkel‎ et al.
  • PloS one‎
  • 2012‎

The enigmatic life cycle and elongated body of the European eel (Anguilla anguilla L., 1758) have long motivated scientific enquiry. Recently, eel research has gained in urgency, as the population has dwindled to the point of critical endangerment. We have assembled a draft genome in order to facilitate advances in all provinces of eel biology. Here, we use the genome to investigate the eel's complement of the Hox developmental transcription factors. We show that unlike any other teleost fish, the eel retains fully populated, duplicate Hox clusters, which originated at the teleost-specific genome duplication. Using mRNA-sequencing and in situ hybridizations, we demonstrate that all copies are expressed in early embryos. Theories of vertebrate evolution predict that the retention of functional, duplicate Hox genes can give rise to additional developmental complexity, which is not immediately apparent in the adult. However, the key morphological innovation elsewhere in the eel's life history coincides with the evolutionary origin of its Hox repertoire.


Platelet-associated CD40/CD154 mediates remote tissue damage after mesenteric ischemia/reperfusion injury.

  • Peter H Lapchak‎ et al.
  • PloS one‎
  • 2012‎

Several innate and adaptive immune cell types participate in ischemia/reperfusion induced tissue injury. Amongst them, platelets have received little attention as contributors in the process of tissue damage after ischemia reperfusion (I/R) injury. It is currently unknown whether platelets participate through the immunologically important molecules including, CD40 and when activated, CD154 (CD40L), in the pathogenesis of I/R injury. We hypothesized that constitutive expression of CD40 and activation-induced expression of CD154 on platelets mediate local mesenteric and remote lung tissue damage after I/R injury. Wild type (WT; C57BL/6J), CD40 and CD154 deficient mice underwent mesenteric ischemia for 30 minutes followed by reperfusion for 3 hours. WT mice subjected to mesenteric I/R injury displayed both local intestinal and remote lung damage. In contrast, there was significantly less intestinal damage and no remote lung injury in CD40 and CD154 deficient mice when compared to WT mice. Platelet-depleted WT mice transfused with platelets from CD40 or CD154 deficient mice failed to reconstitute remote lung damage. In contrast, when CD40 or CD154 deficient mice were transfused with WT platelets lung tissue damage was re-established. Together, these findings suggest that multiple mechanisms are involved in local and remote tissue injury and also identify platelet-expressed CD40 and/or CD154 as mediators of remote tissue damage.


A possible contribution of altered cathepsin B expression to the development of skin sclerosis and vasculopathy in systemic sclerosis.

  • Shinji Noda‎ et al.
  • PloS one‎
  • 2012‎

Cathepsin B (CTSB) is a proteolytic enzyme potentially modulating angiogenic processes and extracellular matrix remodeling. While matrix metalloproteinases are shown to be implicated in tissue fibrosis and vasculopathy associated with systemic sclerosis (SSc), the role of cathepsins in this disease has not been well studied. The aim of this study is to evaluate the roles of CTSB in SSc. Serum pro-CTSB levels were determined by enzyme-linked immunosorbent assay in 55 SSc patients and 19 normal controls. Since the deficiency of transcription factor Fli1 in endothelial cells is potentially associated with the development of SSc vasculopathy, cutaneous CTSB expression was evaluated by immunostaining in Fli1(+/-) and wild type mice as well as in SSc and control subjects. The effects of Fli1 gene silencing and transforming growth factor-β (TGF-β) on CTSB expression were determined by real-time PCR in human dermal microvascular endothelial cells (HDMECs) and dermal fibroblasts, respectively. Serum pro-CTSB levels were significantly higher in limited cutaneous SSc (lcSSc) and late-stage diffuse cutaneous SSc (dcSSc) patients than in healthy controls. In dcSSc, patients with increased serum pro-CTSB levels showed a significantly higher frequency of digital ulcers than those with normal levels. CTSB expression in dermal blood vessels was increased in Fli1(+/-) mice compared with wild type mice and in SSc patients compared with healthy controls. Consistently, Fli1 gene silencing increased CTSB expression in HDMECs. In cultured dermal fibroblasts from early dcSSc, CTSB expression was decreased compared with normal fibroblasts and significantly reversed by TGF-β1 antisense oligonucleotide. In conclusion, up-regulation of endothelial CTSB due to Fli1 deficiency may contribute to the development of SSc vasculopathy, especially digital ulcers, while reduced expression of CTSB in lesional dermal fibroblasts is likely to be associated with skin sclerosis in early dcSSc.


Dectin-1 and DC-SIGN polymorphisms associated with invasive pulmonary Aspergillosis infection.

  • Juan Sainz‎ et al.
  • PloS one‎
  • 2012‎

The recognition of pathogen-derived structures by C-type lectins and the chemotactic activity mediated by the CCL2/CCR2 axis are critical steps in determining the host immune response to fungi. The present study was designed to investigate whether the presence of single nucleotide polymorphisms (SNPs) within DC-SIGN, Dectin-1, Dectin-2, CCL2 and CCR2 genes influence the risk of developing Invasive Pulmonary Aspergillosis (IPA). Twenty-seven SNPs were selected using a hybrid functional/tagging approach and genotyped in 182 haematological patients, fifty-seven of them diagnosed with proven or probable IPA according to the 2008 EORTC/MSG criteria. Association analysis revealed that carriers of the Dectin-1(rs3901533 T/T) and Dectin-1(rs7309123 G/G) genotypes and DC-SIGN(rs4804800 G), DC-SIGN(rs11465384 T), DC-SIGN(7248637 A) and DC-SIGN(7252229 C) alleles had a significantly increased risk of IPA infection (OR = 5.59 95%CI 1.37-22.77; OR = 4.91 95%CI 1.52-15.89; OR = 2.75 95%CI 1.27-5.95; OR = 2.70 95%CI 1.24-5.90; OR = 2.39 95%CI 1.09-5.22 and OR = 2.05 95%CI 1.00-4.22, respectively). There was also a significantly increased frequency of galactomannan positivity among patients carrying the Dectin-1(rs3901533_T) allele and Dectin-1(rs7309123_G/G) genotype. In addition, healthy individuals with this latter genotype showed a significantly decreased level of Dectin-1 mRNA expression compared to C-allele carriers, suggesting a role of the Dectin-1(rs7309123) polymorphism in determining the levels of Dectin-1 and, consequently, the level of susceptibility to IPA infection. SNP-SNP interaction (epistasis) analysis revealed significant interactions models including SNPs in Dectin-1, Dectin-2, CCL2 and CCR2 genes, with synergistic genetic effects. Although these results need to be further validated in larger cohorts, they suggest that Dectin-1, DC-SIGN, Dectin-2, CCL2 and CCR2 genetic variants influence the risk of IPA infection and might be useful in developing a risk-adapted prophylaxis.


Mammalian genes preferentially co-retained in radiation hybrid panels tend to avoid coexpression.

  • Ben-Yang Liao‎ et al.
  • PloS one‎
  • 2012‎

Coexpression has been frequently used to explore modules of functionally related genes in eukaryotic genomes. However, we found that genetically interacting mammalian genes identified through radiation hybrid (RH) genotypes tend not to be coexpressed across tissues. This pattern remained unchanged after controlling for potential confounding factors, including chromosomal linkage, chromosomal distance, and gene duplication. Because >99.9% of the genetically interacting genes were identified according to the higher co-retention frequencies, our observation implies that coexpression is not necessarily an indication of the need for the co-presence of two genes in the genome, which is a prerequisite for cofunctionality of their coding proteins in the cell. Therefore, coexpression information must be applied cautiously to the exploration of the functional relatedness of genes in a genome.


Analysis of the peptidoglycan hydrolase complement of Lactobacillus casei and characterization of the major γ-D-glutamyl-L-lysyl-endopeptidase.

  • Krzysztof Regulski‎ et al.
  • PloS one‎
  • 2012‎

Peptidoglycan (PG) is the major component of Gram positive bacteria cell wall and is essential for bacterial integrity and shape. Bacteria synthesize PG hydrolases (PGHs) which are able to cleave bonds in their own PG and play major roles in PG remodelling required for bacterial growth and division. Our aim was to identify the main PGHs in Lactobacillus casei BL23, a lactic acid bacterium with probiotic properties.The PGH complement was first identified in silico by amino acid sequence similarity searches of the BL23 genome sequence. Thirteen PGHs were detected with different predicted hydrolytic specificities. Transcription of the genes was confirmed by RT-PCR. A proteomic analysis combining the use of SDS-PAGE and LC-MS/MS revealed the main seven PGHs synthesized during growth of L. casei BL23. Among these PGHs, LCABL_02770 (renamed Lc-p75) was identified as the major one. This protein is the homolog of p75 (Msp1) major secreted protein of Lactobacillus rhamnosus GG, which was shown to promote survival and growth of intestinal epithelial cells. We identified its hydrolytic specificity on PG and showed that it is a γ-D-glutamyl-L-lysyl-endopeptidase. It has a marked specificity towards PG tetrapeptide chains versus tripeptide chains and for oligomers rather than monomers. Immunofluorescence experiments demonstrated that Lc-p75 localizes at cell septa in agreement with its role in daughter cell separation. It is also secreted under an active form as detected in zymogram. Comparison of the muropeptide profiles of wild type and Lc-p75-negative mutant revealed a decrease of the amount of disaccharide-dipeptide in the mutant PG in agreement with Lc-p75 activity. As a conclusion, Lc-p75 is the major L. casei BL23 PGH with endopeptidase specificity and a key role in daughter cell separation. Further studies will aim at investigating the role of Lc-p75 in the anti-inflammatory potential of L. casei BL23.


Combined chromatin and expression analysis reveals specific regulatory mechanisms within cytokine genes in the macrophage early immune response.

  • Maria Jesus Iglesias‎ et al.
  • PloS one‎
  • 2012‎

Macrophages play a critical role in innate immunity, and the expression of early response genes orchestrate much of the initial response of the immune system. Macrophages undergo extensive transcriptional reprogramming in response to inflammatory stimuli such as Lipopolysaccharide (LPS).To identify gene transcription regulation patterns involved in early innate immune responses, we used two genome-wide approaches--gene expression profiling and chromatin immunoprecipitation-sequencing (ChIP-seq) analysis. We examined the effect of 2 hrs LPS stimulation on early gene expression and its relation to chromatin remodeling (H3 acetylation; H3Ac) and promoter binding of Sp1 and RNA polymerase II phosphorylated at serine 5 (S5P RNAPII), which is a marker for transcriptional initiation. Our results indicate novel and alternative gene regulatory mechanisms for certain proinflammatory genes. We identified two groups of up-regulated inflammatory genes with respect to chromatin modification and promoter features. One group, including highly up-regulated genes such as tumor necrosis factor (TNF), was characterized by H3Ac, high CpG content and lack of TATA boxes. The second group, containing inflammatory mediators (interleukins and CCL chemokines), was up-regulated upon LPS stimulation despite lacking H3Ac in their annotated promoters, which were low in CpG content but did contain TATA boxes. Genome-wide analysis showed that few H3Ac peaks were unique to either +/-LPS condition. However, within these, an unpacking/expansion of already existing H3Ac peaks was observed upon LPS stimulation. In contrast, a significant proportion of S5P RNAPII peaks (approx 40%) was unique to either condition. Furthermore, data indicated a large portion of previously unannotated TSSs, particularly in LPS-stimulated macrophages, where only 28% of unique S5P RNAPII peaks overlap annotated promoters. The regulation of the inflammatory response appears to occur in a very specific manner at the chromatin level for specific genes and this study highlights the level of fine-tuning that occurs in the immune response.


Phenotypic plasticity influences the size, shape and dynamics of the geographic distribution of an invasive plant.

  • Jean-Baptiste Pichancourt‎ et al.
  • PloS one‎
  • 2012‎

Phenotypic plasticity has long been suspected to allow invasive species to expand their geographic range across large-scale environmental gradients. We tested this possibility in Australia using a continental scale survey of the invasive tree Parkinsonia aculeata (Fabaceae) in twenty-three sites distributed across four climate regions and three habitat types. Using tree-level responses, we detected a trade-off between seed mass and seed number across the moisture gradient. Individual trees plastically and reversibly produced many small seeds at dry sites or years, and few big seeds at wet sites and years. Bigger seeds were positively correlated with higher seed and seedling survival rates. The trade-off, the relation between seed mass, seed and seedling survival, and other fitness components of the plant life-cycle were integrated within a matrix population model. The model confirms that the plastic response resulted in average fitness benefits across the life-cycle. Plasticity resulted in average fitness being positively maintained at the wet and dry range margins where extinction risks would otherwise have been high ("Jack-of-all-Trades" strategy JT), and fitness being maximized at the species range centre where extinction risks were already low ("Master-of-Some" strategy MS). The resulting hybrid "Jack-and-Master" strategy (JM) broadened the geographic range and amplified average fitness in the range centre. Our study provides the first empirical evidence for a JM species. It also confirms mechanistically the importance of phenotypic plasticity in determining the size, the shape and the dynamic of a species distribution. The JM allows rapid and reversible phenotypic responses to new or changing moisture conditions at different scales, providing the species with definite advantages over genetic adaptation when invading diverse and variable environments. Furthermore, natural selection pressure acting on phenotypic plasticity is predicted to result in maintenance of the JT and strengthening of the MS, further enhancing the species invasiveness in its range centre.


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