99901
|
Johnson V, Ayaz P, Huddleston P, Rice LM. Design, overexpression, and purification of polymerization-blocked yeast αβ-tubulin mutants. Biochemistry 2011; 50:8636-44. [PMID: 21888381 DOI: 10.1021/bi2005174] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microtubule dynamics play essential roles in intracellular organization and cell division. They result from structural and biochemical properties of αβ-tubulin heterodimers and how these polymerizing subunits interact with themselves and with regulatory proteins. A broad understanding of the underlying mechanisms has been established, but fundamental questions remain unresolved. The lack of routine access to recombinant αβ-tubulin represents an obstacle to deeper insight into αβ-tubulin structure, biochemistry, and recognition. Indeed, the widespread reliance on animal brain αβ-tubulin means that very few in vitro studies have taken advantage of powerful and ordinarily routine techniques like site-directed mutagenesis. Here we report new methods for purifying wild-type or mutant yeast αβ-tubulin from inducibly overexpressing strains of Saccharomyces cerevisiae. Inducible overexpression is an improvement over existing approaches that rely on constitutive expression: it provides higher yields while also allowing otherwise lethal mutants to be purified. We also designed and purified polymerization-blocked αβ-tubulin mutants. These "blocked" forms of αβ-tubulin give a dominant lethal phenotype when expressed in cells; they cannot form microtubules in vitro and when present in mixtures inhibit the polymerization of wild-type αβ-tubulin. The effects of blocking mutations are very specific, because purified mutants exhibit normal hydrodynamic properties, bind GTP, and interact with a tubulin-binding domain. The ability to overexpress and purify wild-type αβ-tubulin, or mutants like the ones we report here, creates new opportunities for structural studies of αβ-tubulin and its complexes with regulatory proteins, and for biochemical and functional studies of microtubule dynamics and its regulation.
Collapse
Affiliation(s)
- Vinu Johnson
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | | | | | | |
Collapse
|
99902
|
Fogel AI, Stagi M, Perez de Arce K, Biederer T. Lateral assembly of the immunoglobulin protein SynCAM 1 controls its adhesive function and instructs synapse formation. EMBO J 2011; 30:4728-38. [PMID: 21926970 DOI: 10.1038/emboj.2011.336] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 08/18/2011] [Indexed: 11/09/2022] Open
Abstract
Synapses are specialized adhesion sites between neurons that are connected by protein complexes spanning the synaptic cleft. These trans-synaptic interactions can organize synapse formation, but their macromolecular properties and effects on synaptic morphology remain incompletely understood. Here, we demonstrate that the synaptic cell adhesion molecule SynCAM 1 self-assembles laterally via its extracellular, membrane-proximal immunoglobulin (Ig) domains 2 and 3. This cis oligomerization generates SynCAM oligomers with increased adhesive capacity and instructs the interactions of this molecule across the nascent and mature synaptic cleft. In immature neurons, cis assembly promotes the adhesive clustering of SynCAM 1 at new axo-dendritic contacts. Interfering with the lateral self-assembly of SynCAM 1 in differentiating neurons strongly impairs its synaptogenic activity. At later stages, the lateral oligomerization of SynCAM 1 restricts synaptic size, indicating that this adhesion molecule contributes to the structural organization of synapses. These results support that lateral interactions assemble SynCAM complexes within the synaptic cleft to promote synapse induction and modulate their structure. These findings provide novel insights into synapse development and the adhesive mechanisms of Ig superfamily members.
Collapse
Affiliation(s)
- Adam I Fogel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | | | | | | |
Collapse
|
99903
|
Sareddy GR, Geeviman K, Panigrahi M, Challa S, Mahadevan A, Babu PP. Increased β-catenin/Tcf signaling in pilocytic astrocytomas: a comparative study to distinguish pilocytic astrocytomas from low-grade diffuse astrocytomas. Neurochem Res 2011; 37:96-104. [PMID: 21922255 DOI: 10.1007/s11064-011-0586-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 08/29/2011] [Indexed: 01/14/2023]
Abstract
Although pilocytic and diffuse grade II astrocytomas considered as low-grade tumors, the distinction between them is still a major clinical problem. Previously we reported the activation of Wnt/β-catenin/Tcf signaling pathway in diffuse astrocytomas, however its role in pilocytic astrocytomas is not well understood. In this study, we investigated the Wnt/β-catenin/Tcf pathway in pilocytic astrocytomas and compared with diffuse astrocytomas. We observed the differential expression of β-catenin, Tcf4, Lef1 and c-Myc in astrocytomas particularly higher levels were observed in pilocytic astrocytomas and GBM while very little expression was documented in grade II tumors. Further, immunohistochemical analysis revealed the strong positivity of β-catenin, Tcf4, Lef1 and c-Myc in pilocytic astrocytomas than that of grade II tumors and also exhibited the strong positivity in vascular endothelial cells of pilocytic astrocytomas and GBM. Hence, Wnt/β-catenin/Tcf signaling pathway is differentially expressed in astrocytomas, activation of this pathway might be helpful in separating pilocytic astrocytomas from low-grade diffuse astrocytomas.
Collapse
Affiliation(s)
- Gangadhara Reddy Sareddy
- Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | | | | | | | | | | |
Collapse
|
99904
|
Yosha L, Ravid O, Ben-Califa N, Neumann D. Cytosolic lysine residues enhance anterograde transport and activation of the erythropoietin receptor. Biochem J 2011; 435:509-18. [PMID: 21291419 DOI: 10.1042/BJ20101876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Lysine residues are key residues in many cellular processes, in part due to their ability to accept a wide variety of post-translational modifications. In the present study, we identify the EPO-R [EPO (erythropoietin) receptor] cytosolic lysine residues as enhancers of receptor function. EPO-R drives survival, proliferation and differentiation of erythroid progenitor cells via binding of its ligand EPO. We mutated the five EPO-R cytosolic lysine residues to arginine residues (5KR EPO-R), eliminating putative lysine-dependent modifications. Overexpressed 5KR EPO-R displayed impaired ubiquitination and improved stability compared with wt (wild-type) EPO-R. Unexpectedly, fusion proteins consisting of VSVGtsO45 (vesicular stomatitis virus glycoprotein temperature-sensitive folding mutant) with wt or 5KR EPO-R cytosolic domains demonstrated delayed glycan maturation kinetics upon substitution of the lysine residues. Moreover, VSVG-wt EPO-R, but not VSVG-5KR EPO-R, displayed endoplasmic reticulum-associated ubiquitination. Despite similar cell-surface EPO-binding levels of both receptors and the lack of EPO-induced ubiquitination by 5KR EPO-R, the lysine-less mutant produced weaker receptor activation and signalling than the wt receptor. We thus propose that EPO-R cytosolic lysine residues enhance receptor function, most probably through ubiquitination and/or other post-translational modifications.
Collapse
|
99905
|
Abstract
Recent experiments on nucleoli suggest that their dynamic behavior is liquid-like with common fusion events and that the surrounding actin plays an active role in these dynamics.
Collapse
|
99906
|
Park SC, Park Y, Hahm KS. The role of antimicrobial peptides in preventing multidrug-resistant bacterial infections and biofilm formation. Int J Mol Sci 2011; 12:5971-92. [PMID: 22016639 DOI: 10.3390/ijms12095971] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 09/05/2011] [Accepted: 09/06/2011] [Indexed: 01/21/2023] Open
Abstract
Over the last decade, decreasing effectiveness of conventional antimicrobial-drugs has caused serious problems due to the rapid emergence of multidrug-resistant pathogens. Furthermore, biofilms, which are microbial communities that cause serious chronic infections and dental plaque, form environments that enhance antimicrobial resistance. As a result, there is a continuous search to overcome or control such problems, which has resulted in antimicrobial peptides being considered as an alternative to conventional drugs. Antimicrobial peptides are ancient host defense effector molecules in living organisms. These peptides have been identified in diverse organisms and synthetically developed by using peptidomimic techniques. This review was conducted to demonstrate the mode of action by which antimicrobial peptides combat multidrug-resistant bacteria and prevent biofilm formation and to introduce clinical uses of these compounds for chronic disease, medical devices, and oral health. In addition, combinations of antimicrobial peptides and conventional drugs were considered due to their synergetic effects and low cost for therapeutic treatment.
Collapse
|
99907
|
Heinrich EL, Walser TC, Krysan K, Liclican EL, Grant JL, Rodriguez NL, Dubinett SM. The inflammatory tumor microenvironment, epithelial mesenchymal transition and lung carcinogenesis. Cancer Microenviron 2011; 5:5-18. [PMID: 21922183 DOI: 10.1007/s12307-011-0089-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 08/30/2011] [Indexed: 12/21/2022]
Abstract
The inflammatory tumor microenvironment (TME) has many roles in tumor progression and metastasis, including creation of a hypoxic environment, increased angiogenesis and invasion, changes in expression of microRNAs (miRNAs) and an increase in a stem cell phenotype. Each of these has an impact on epithelial mesenchymal transition (EMT), particularly through the downregulation of E-cadherin. Here we review seminal work and recent findings linking the role of inflammation in the TME, EMT and lung cancer initiation, progression and metastasis. Finally, we discuss the potential of targeting aspects of inflammation and EMT in cancer prevention and treatment.
Collapse
Affiliation(s)
- Eileen L Heinrich
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, 37-131 CHS Building, Los Angeles, CA, 90095, USA
| | | | | | | | | | | | | |
Collapse
|
99908
|
Han WQ, Xia M, Zhang C, Zhang F, Xu M, Li NJ, Li PL. SNARE-mediated rapid lysosome fusion in membrane raft clustering and dysfunction of bovine coronary arterial endothelium. Am J Physiol Heart Circ Physiol 2011; 301:H2028-37. [PMID: 21926345 DOI: 10.1152/ajpheart.00581.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The present study attempted to evaluate whether soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediate lysosome fusion in response to death receptor activation and contribute to membrane raft (MR) clustering and consequent endothelial dysfunction in coronary arterial endothelial cells. By immunohistochemical analysis, vesicle-associated membrane proteins 2 (VAMP-2, vesicle-SNAREs) were found to be abundantly expressed in the endothelium of bovine coronary arteries. Direct lysosome fusion monitoring by N-(3-triethylammoniumpropyl)-4-[4-(dibutylamino)styryl]pyridinium dibromide (FM1-43) quenching demonstrated that the inhibition of VAMP-2 with tetanus toxin or specific small interfering ribonucleic acid (siRNA) almost completely blocked lysosome fusion to plasma membrane induced by Fas ligand (FasL), a well-known MR clustering stimulator. The involvement of SNAREs was further confirmed by an increased interaction of VAMP-2 with a target-SNARE protein syntaxin-4 after FasL stimulation in coimmunoprecipitation analysis. Also, the inhibition of VAMP-2 with tetanus toxin or VAMP-2 siRNA abolished FasL-induced MR clustering, its colocalization with a NADPH oxidase unit gp91(phox), and increased superoxide production. Finally, FasL-induced impairment of endothelium-dependent vasodilation was reversed by the treatment of bovine coronary arteries with tetanus toxin or VAMP-2 siRNA. VAMP-2 is critical to lysosome fusion in MR clustering, and this VAMP-2-mediated lysosome-MR signalosomes contribute to redox regulation of coronary endothelial function.
Collapse
Affiliation(s)
- Wei-Qing Han
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA
| | | | | | | | | | | | | |
Collapse
|
99909
|
Abstract
Autophagy, one of two major intracellular degradation pathways, plays a critical role in energy homeostasis and the quality control of macromolecules and intracellular organelles. Previous work has demonstrated the importance of autophagy in maintaining cellular fitness, both in healthy and stressful conditions, revealing the complex interplay between autophagy and other stress-responsive phenotypes. The complex outcomes of stress-responsive autophagy confer on it both pro- and anti-tumourigenic roles, depending on the cellular and environmental context. Furthermore, recent findings that functionally link autophagy to the tumour suppressor mechanism, cellular senescence, have revealed a new role of autophagy in cancer biology. In this review we summarise the current evidence on the relationship between autophagy and cancer, with a focus on its role in senescence.
Collapse
Affiliation(s)
- Matthew Hoare
- Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | | | | |
Collapse
|
99910
|
Abstract
Watching biological molecules provides clues to their function and regulation. Some of the most powerful methods of labeling proteins for imaging use genetically encoded fluorescent fusion tags. There are four standard genetic methods of covalently tagging a protein with a fluorescent probe for cellular imaging. These use (i) autofluorescent proteins, (ii) self-labeling enzymes, (iii) enzymes that catalyze the attachment of a probe to a target sequence, and (iv) biarsenical dyes that target tetracysteine motifs. Each of these techniques has advantages and disadvantages. In this review, we cover new developments in these methods and discuss practical considerations for their use in imaging proteins inside living cells.
Collapse
Affiliation(s)
- Georgeta Crivat
- University of Maryland, College Park, Department of Entomology and Program in Cell and Molecular Biology, College Park, MD 20742, USA
| | | |
Collapse
|
99911
|
Charalambous A, Antoniades I, Christodoulou N, Skourides PA. Split-inteins for simultaneous, site-specific conjugation of quantum dots to multiple protein targets in vivo. J Nanobiotechnology 2011; 9:37. [PMID: 21920033 PMCID: PMC3196691 DOI: 10.1186/1477-3155-9-37] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 09/15/2011] [Indexed: 02/05/2023] Open
Abstract
Background Proteins labelled with Quantum Dots (QDs) can be imaged over long periods of time with ultrahigh spatial and temporal resolution, yielding important information on the spatiotemporal dynamics of proteins within live cells or in vivo. However one of the major problems regarding the use of QDs for biological imaging is the difficulty of targeting QDs onto proteins. We have recently developed a DnaE split intein-based method to conjugate Quantum Dots (QDs) to the C-terminus of target proteins in vivo. In this study, we expand this approach to achieve site-specific conjugation of QDs to two or more proteins simultaneously with spectrally distinguishable QDs for multiparameter imaging of cellular functions. Results Using the DnaE split intein we target QDs to the C-terminus of paxillin and show that paxillin-QD conjugates become localized at focal adhesions allowing imaging of the formation and dissolution of these complexes. We go on to utilize a different split intein, namely Ssp DnaB mini-intein, to demonstrate N-terminal protein tagging with QDs. Combination of these two intein systems allowed us to simultaneously target two distinct proteins with spectrally distinguishable QDs, in vivo, without any cross talk between the two intein systems. Conclusions Multiple target labeling is a unique feature of the intein based methodology which sets it apart from existing tagging methodologies in that, given the large number of characterized split inteins, the number of individual targets that can be simultaneously tagged is only limited by the number of QDs that can be spectrally distinguished within the cell. Therefore, the intein-mediated approach for simultaneous, in vivo, site-specific (N- and C-terminus) conjugation of Quantum Dots to multiple protein targets opens up new possibilities for bioimaging applications and offers an effective system to target QDs and other nanostructures to intracellular compartments as well as specific molecular complexes.
Collapse
Affiliation(s)
- Anna Charalambous
- Department of Biological Sciences, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
| | | | | | | |
Collapse
|
99912
|
Abstract
From hormonal secretion to gene expression, multicellular dynamics are rich in oscillatory regulation. When organized in space and time, periodic cell-cell signaling can give rise to long-range coordination of gene expression and cell movement in tissues. Lack of synchrony of the oscillations on the other hand can serve as a source of initial divergence of cell fate in stem cells. How properties of individual cells can account for collective rhythmic behaviors at the tissue level remains elusive in most cases. Recently, studies in chemical reactions, synthetic gene circuits, yeast and social amoeba Dictyostelium have greatly enhanced our view of collective oscillations in cell populations. From these relatively simple systems, a unified view of how excitable and oscillatory regulations could be tuned and coupled to give rise to tissue-level oscillations is emerging. The review focuses on recent progress in cyclic adenosine monophosphate oscillations in Dictyostelium and highlights similarities and differences with other systems. We will see that the autonomy of single-cell level oscillations and different ways in which cells are coupled influence how group-level information can be encoded in collective oscillations.
Collapse
Affiliation(s)
- Keita Kamino
- Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, Japan
| | | | | |
Collapse
|
99913
|
Garner AL, Park J, Zakhari JS, Lowery CA, Struss AK, Sawada D, Kaufmann GF, Janda KD. A multivalent probe for AI-2 quorum-sensing receptors. J Am Chem Soc 2011; 133:15934-7. [PMID: 21913711 DOI: 10.1021/ja207556d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multivalency is a common principle in the recognition of cellular receptors, and multivalent agonists and antagonists have played a major role in understanding mammalian cell receptor biology. The study of bacterial cell receptors using similar approaches, however, has lagged behind. Herein we describe our efforts toward the development of a dendrimer-based multivalent probe for studying AI-2 quorum-sensing receptors. From these studies, we have discovered a chemical probe specific for Lsr-type AI-2 quorum-sensing receptors with the potential for enabling the identification of new bacterial species that utilize AI-2 as a quorum-sensing signaling molecule.
Collapse
Affiliation(s)
- Amanda L Garner
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | | | | | | | | | | | | | | |
Collapse
|
99914
|
Guilluy C, Garcia-Mata R, Burridge K. Rho protein crosstalk: another social network? Trends Cell Biol 2011; 21:718-26. [PMID: 21924908 DOI: 10.1016/j.tcb.2011.08.002] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 08/02/2011] [Accepted: 08/04/2011] [Indexed: 12/13/2022]
Abstract
Many fundamental processes in cell biology are regulated by Rho GTPases, including cell adhesion, migration and differentiation. While regulating cellular functions, members of the Rho protein family cooperate or antagonize each other. The resulting molecular network exhibits many levels of interaction dynamically regulated in time and space. In the first part of this review we describe the main mechanisms of this crosstalk, which can occur at three different levels of the pathway: (i) through regulation of activity, (ii) through regulation of protein expression and stability, and (iii) through regulation of downstream signaling pathways. In the second part we illustrate the importance of Rho protein crosstalk with two examples: integrin-based adhesion and cell migration.
Collapse
Affiliation(s)
- Christophe Guilluy
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | | | | |
Collapse
|
99915
|
Gong H, Vu GP, Bai Y, Chan E, Wu R, Yang E, Liu F, Lu S. A Salmonella small non-coding RNA facilitates bacterial invasion and intracellular replication by modulating the expression of virulence factors. PLoS Pathog 2011; 7:e1002120. [PMID: 21949647 PMCID: PMC3174252 DOI: 10.1371/journal.ppat.1002120] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 04/29/2011] [Indexed: 12/17/2022] Open
Abstract
Small non-coding RNAs (sRNAs) that act as regulators of gene expression have been identified in all kingdoms of life, including microRNA (miRNA) and small interfering RNA (siRNA) in eukaryotic cells. Numerous sRNAs identified in Salmonella are encoded by genes located at Salmonella pathogenicity islands (SPIs) that are commonly found in pathogenic strains. Whether these sRNAs are important for Salmonella pathogenesis and virulence in animals has not been reported. In this study, we provide the first direct evidence that a pathogenicity island-encoded sRNA, IsrM, is important for Salmonella invasion of epithelial cells, intracellular replication inside macrophages, and virulence and colonization in mice. IsrM RNA is expressed in vitro under conditions resembling those during infection in the gastrointestinal tract. Furthermore, IsrM is found to be differentially expressed in vivo, with higher expression in the ileum than in the spleen. IsrM targets the mRNAs coding for SopA, a SPI-1 effector, and HilE, a global regulator of the expression of SPI-1 proteins, which are major virulence factors essential for bacterial invasion. Mutations in IsrM result in disregulation of expression of HilE and SopA, as well as other SPI-1 genes whose expression is regulated by HilE. Salmonella with deletion of isrM is defective in bacteria invasion of epithelial cells and intracellular replication/survival in macrophages. Moreover, Salmonella with mutations in isrM is attenuated in killing animals and defective in growth in the ileum and spleen in mice. Our study has shown that IsrM sRNA functions as a pathogenicity island-encoded sRNA directly involved in Salmonella pathogenesis in animals. Our results also suggest that sRNAs may represent a distinct class of virulence factors that are important for bacterial infection in vivo. Regulated expression of virulence factors is essential for infection by human pathogens such as Salmonella. Small non-coding RNAs (sRNAs) that act as regulators of gene expression have been identified in all kingdoms of life, and many sRNAs in Salmonella are encoded by genes located at Salmonella pathogenicity islands commonly found in pathogenic strains. In this study, we demonstrated that a pathogenicity island-encoded sRNA directly targets the expression of both a global regulator of virulence genes as well as a specific virulence factor critical for Salmonella pathogenesis. The sRNA is important for Salmonella invasion of epithelial cells, replication inside macrophages, and virulence/colonization in mice, representing the first example of a pathogenicity island-encoded sRNA that is directly involved in Salmonella pathogenesis in vivo. Our study suggests that sRNA may function as a distinct class of virulence factors that significantly contribute to bacterial infection in vivo. Furthermore, our results raise the possibility of developing new strategies against bacterial infection by preventing the expression of regulatory sRNAs.
Collapse
MESH Headings
- 5' Untranslated Regions
- Animals
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Base Sequence
- Epithelial Cells/microbiology
- Epithelial Cells/pathology
- Female
- Gastrointestinal Tract/cytology
- Gastrointestinal Tract/microbiology
- Gene Expression Regulation, Bacterial
- Genomic Islands
- Ileum/cytology
- Macrophages/microbiology
- Mice
- Mice, Inbred BALB C
- Mice, SCID
- Promoter Regions, Genetic
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/genetics
- RNA, Small Untranslated/genetics
- RNA, Small Untranslated/metabolism
- Salmonella Infections, Animal/microbiology
- Salmonella Infections, Animal/pathology
- Salmonella typhimurium/genetics
- Salmonella typhimurium/growth & development
- Salmonella typhimurium/metabolism
- Salmonella typhimurium/pathogenicity
- Sequence Alignment
- Sequence Analysis
- Spleen/cytology
- Virulence Factors/biosynthesis
- Virulence Factors/genetics
Collapse
Affiliation(s)
- Hao Gong
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, California, United States of America
| | - Gia-Phong Vu
- Program in Comparative Biochemistry, University of California, Berkeley, California, United States of America
| | - Yong Bai
- Program in Comparative Biochemistry, University of California, Berkeley, California, United States of America
| | - Elton Chan
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, California, United States of America
| | - Ruobin Wu
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, California, United States of America
| | - Edward Yang
- Program in Comparative Biochemistry, University of California, Berkeley, California, United States of America
| | - Fenyong Liu
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, California, United States of America
- Program in Comparative Biochemistry, University of California, Berkeley, California, United States of America
- * E-mail: (FL); (SL)
| | - Sangwei Lu
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, California, United States of America
- Program in Comparative Biochemistry, University of California, Berkeley, California, United States of America
- * E-mail: (FL); (SL)
| |
Collapse
|
99916
|
Abstract
The major cause of hemodialysis vascular access failure is venous stenosis resulting from neointimal hyperplasia. Genetic factors have been shown to be associated with cardiovascular disease and peripheral vascular disease (PVD) in the general population. Genetic factors may also play an important role in vascular access stenosis and development of neointimal hyperplasia by affecting pathways that lead to inflammation, endothelial function, oxidative stress, and vascular smooth muscle proliferation. This review will discuss the role of genetics in understanding neointimal hyperplasia development in hemodialysis vascular access dysfunction and other disease processes with similar neointimal hyperplasia development such as coronary artery disease and PVD.
Collapse
Affiliation(s)
- Timmy Lee
- Department of Internal Medicine, Division of Nephrology and Hypertension, University of Cincinnati, Cincinnati, Ohio 45267-0585, USA.
| | | |
Collapse
|
99917
|
Abstract
The constitutive photomorphogenesis 9 signalosome (COP9 or CSN) is an evolutionarily conserved multiprotein complex found in plants and animals. Because of the homology between the COP9 signalosome and the 19S lid complex of the proteosome, COP9 has been postulated to play a role in regulating the degradation of polyubiquitinated proteins. Many tumor suppressor and oncogene products are regulated by ubiquitination- and proteosome-mediated protein degradation. Therefore, it is conceivable that COP9 plays a significant role in cancer, regulating processes relevant to carcinogenesis and cancer progression (e.g., cell cycle control, signal transduction and apoptosis). In mammalian cells, it consists of eight subunits (CSN1 to CSN8). The relevance and importance of some subunits of COP9 to cancer are emerging. However, the mechanistic regulation of each subunit in cancer remains unclear. Among the CSN subunits, CSN5 and CSN6 are the only two that each contain an MPN (Mpr1p and Pad1p N-terminal) domain. The deneddylation activity of an MPN domain toward cullin-RING ubiquitin ligases (CRL) may coordinate CRL-mediated ubiquitination activity. More recent evidence shows that CSN5 and CSN6 are implicated in ubiquitin-mediated proteolysis of important mediators in carcinogenesis and cancer progression. Here, we discuss the mechanisms by which some CSN subunits are involved in cancer to provide a much needed perspective regarding COP9 in cancer research, hoping that these insights will lay the groundwork for cancer intervention.
Collapse
Affiliation(s)
- Mong-Hong Lee
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| | | | | | | |
Collapse
|
99918
|
Tullai JW, Graham JR, Cooper GM. A GSK-3-mediated transcriptional network maintains repression of immediate early genes in quiescent cells. Cell Cycle 2011; 10:3072-7. [PMID: 21900749 DOI: 10.4161/cc.10.18.17321] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Glycogen synthase kinase-3 (GSK-3) plays a central role in cell survival and proliferation, in part by the regulation of transcription. Unlike most protein kinases, GSK-3 is active in quiescent cells in the absence of growth factor signaling. In a recent series of studies, we employed a systems-level approach to understanding the transcription network regulated by GSK-3 in a quiescent cell model. We identified a group of immediate early genes that were upregulated in quiescent cells solely by the inhibition of GSK-3 in the absence of growth factor stimulation. Computational analysis of the upstream sequences of these genes identified statistically over-represented binding sites for the transcription factors CREB, NFκB and AP-1, and the roles of these factors in regulating expression of GSK-3 target genes were verified by chromatin immunoprecipitation and RNA interference. In quiescent cells, GSK-3 inhibits CREB, NFκB and AP-1, thereby maintaining repression of their target genes and contributing to maintenance of cell cycle arrest.
Collapse
|
99919
|
Malladi VLA, Sobczak AJ, Meyer TM, Pei D, Wnuk SF. Inhibition of LuxS by S-ribosylhomocysteine analogues containing a [4-aza]ribose ring. Bioorg Med Chem 2011; 19:5507-19. [PMID: 21855358 PMCID: PMC3171632 DOI: 10.1016/j.bmc.2011.07.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2011] [Revised: 07/12/2011] [Accepted: 07/22/2011] [Indexed: 01/19/2023]
Abstract
LuxS (S-ribosylhomocysteinase) catalyzes the cleavage of the thioether linkage of S-ribosylhomocysteine (SRH) to produce homocysteine and 4,5-dihydroxy-2,3-pentanedione (DPD), the precursor to a small signaling molecule that mediates interspecies bacterial communication called autoinducer 2 (AI-2). Inhibitors of LuxS should interfere with bacterial interspecies communication and potentially provide a novel class of antibacterial agents. In this work, SRH analogues containing substitution of a nitrogen atom for the endocyclic oxygen as well as various deoxyriboses were synthesized and evaluated for LuxS inhibition. Two of the [4-aza]SRH analogues showed modest competitive inhibition (K(I) ∼40 μM), while most of the others were inactive. One compound that contains a hemiaminal moiety exhibited time-dependent inhibition, consistent with enzyme-catalyzed ring opening and conversion into a more potent species (K(I)(∗)=3.5 μM). The structure-activity relationship of the designed inhibitors highlights the importance of both the homocysteine and ribose moieties for high-affinity binding to LuxS active site.
Collapse
Affiliation(s)
- Venkata L. A. Malladi
- Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Adam J. Sobczak
- Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199, USA
- On a faculty leave from University of Life Sciences, Department of Chemistry, Poznan, Poland
| | - Tiffany M. Meyer
- Department of Chemistry and Ohio State Biochemistry program, The Ohio State University, 100 West 18 Avenue, Columbus, Ohio 43210, USA
| | - Dehua Pei
- Department of Chemistry and Ohio State Biochemistry program, The Ohio State University, 100 West 18 Avenue, Columbus, Ohio 43210, USA
| | - Stanislaw F. Wnuk
- Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199, USA
| |
Collapse
|
99920
|
CHIODIN MARTA, ACHATZ JOHANNESG, WANNINGER ANDREAS, MARTINEZ PEDRO. Molecular architecture of muscles in an acoel and its evolutionary implications. J Exp Zool B Mol Dev Evol 2011; 316:427-39. [PMID: 21538843 PMCID: PMC3501712 DOI: 10.1002/jez.b.21416] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 03/12/2011] [Accepted: 04/01/2011] [Indexed: 12/14/2022]
Abstract
We have characterized the homologs of an actin, a troponin I, and a tropomyosin gene in the acoel Symsagittifera roscoffensis. These genes are expressed in muscles and most likely coexpressed in at least a subset of them. In addition, and for the first time for Acoela, we have produced a species-specific muscular marker, an antibody against the tropomyosin protein. We have followed tropomyosin gene and protein expression during postembryonic development and during the posterior regeneration of amputated adults, showing that preexisting muscle fibers contribute to the wound closure. The three genes characterized in this study interact in the striated muscles of vertebrates and invertebrates, where troponin I and tropomyosin are key regulators of the contraction of the sarcomere. S. roscoffensis and all other acoels so far described have only smooth muscles, but the molecular architecture of these is the same as that of striated fibers of other bilaterians. Given the proposed basal position of acoels within the Bilateria, we suggest that sarcomeric muscles arose from a smooth muscle type, which had the molecular repertoire of striated musculature already in place. We discuss this model in a broad comparative perspective.
Collapse
Affiliation(s)
- MARTA CHIODIN
- Departament de Genètica, Universitat de Barcelona, Barcelona, Spain
| | | | - ANDREAS WANNINGER
- Department of Evolutionary Biology, Section of Morphology, University of Vienna, Vienna, Austria
| | - PEDRO MARTINEZ
- Departament de Genètica, Universitat de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys, Barcelona, Spain
| |
Collapse
|
99921
|
Yang XM, Yafai Y, Wiedemann P, Kuhrt H, Wang YS, Reichenbach A, Eichler W. Hypoxia-induced upregulation of pigment epithelium-derived factor by retinal glial (Müller) cells. J Neurosci Res 2011; 90:257-66. [DOI: 10.1002/jnr.22732] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 06/06/2011] [Accepted: 06/06/2011] [Indexed: 11/11/2022]
|
99922
|
Guo D, Reinitz F, Youssef M, Hong C, Nathanson D, Akhavan D, Kuga D, Amzajerdi AN, Soto H, Zhu S, Babic I, Tanaka K, Dang J, Iwanami A, Gini B, Dejesus J, Lisiero DD, Huang TT, Prins RM, Wen PY, Robins HI, Prados MD, Deangelis LM, Mellinghoff IK, Mehta MP, James CD, Chakravarti A, Cloughesy TF, Tontonoz P, Mischel PS. An LXR agonist promotes glioblastoma cell death through inhibition of an EGFR/AKT/SREBP-1/LDLR-dependent pathway. Cancer Discov 2011; 1:442-56. [PMID: 22059152 DOI: 10.1158/2159-8290.cd-11-0102] [Citation(s) in RCA: 305] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Glioblastoma (GBM) is the most common malignant primary brain tumor of adults and one of the most lethal of all cancers. Epidermal growth factor receptor (EGFR) mutations (EGFRvIII) and phosphoinositide 3-kinase (PI3K) hyperactivation are common in GBM, promoting tumor growth and survival, including through sterol regulatory element-binding protein 1 (SREBP-1)-dependent lipogenesis. The role of cholesterol metabolism in GBM pathogenesis, its association with EGFR/PI3K signaling, and its potential therapeutic targetability are unknown. In our investigation, studies of GBM cell lines, xenograft models, and GBM clinical samples, including those from patients treated with the EGFR tyrosine kinase inhibitor lapatinib, uncovered an EGFRvIII-activated, PI3K/SREBP-1-dependent tumor survival pathway through the low-density lipoprotein receptor (LDLR). Targeting LDLR with the liver X receptor (LXR) agonist GW3965 caused inducible degrader of LDLR (IDOL)-mediated LDLR degradation and increased expression of the ABCA1 cholesterol efflux transporter, potently promoting tumor cell death in an in vivo GBM model. These results show that EGFRvIII can promote tumor survival through PI3K/SREBP-1-dependent upregulation of LDLR and suggest a role for LXR agonists in the treatment of GBM patients.
Collapse
Affiliation(s)
- Deliang Guo
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University Medical School, Columbus, OH, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
99923
|
Abstract
Ubiquitination is a post-translational modification that generally directs proteins for degradation by the proteasome or by lysosomes. However, ubiquitination has been implicated in many other cellular processes, including transcriptional regulation, DNA repair, regulation of protein-protein interactions and association with ubiquitin-binding scaffolds. Ubiquitination is a dynamic process. Ubiquitin is added to proteins by E3 ubiquitin ligases as a covalent modification to one or multiple lysine residues as well as non-lysine amino acids. Ubiquitin itself contains seven lysines, each of which can also be ubiquitinated, leading to polyubiquitin chains that are best characterized for linkages occurring through K48 and K63. Ubiquitination can also be reversed by the action of deubiquitination enzymes (DUbs). Like E3 ligases, DUbs play diverse and critical roles in cells. ( 1) Ubiquitin is expressed as a fusion protein, as a linear repeat or as a fusion to ribosomal subunits, and DUbs are necessary to liberate free ubiquitin, making them the first enzyme of the ubiquitin cascade. Proteins destined for degradation by the proteasome or by lysosomes are deubiquitinated prior to their degradation, which allows ubiquitin to be recycled by the cell, contributing to the steady-state pool of free ubiquitin. Proteins destined for degradation by lysosomes are also acted upon by both ligases and DUbs. Deubiquitination can also act as a means to prevent protein degradation, and many proteins are thought to undergo rounds of ubiquitination and deubiquitination, ultimately resulting in either the degradation or stabilization of those proteins. Despite years of study, examining the effects of the ubiquitination of proteins remains quite challenging. This is because the methods that are currently being employed to study ubiquitination are limiting. Here, we briefly examine current strategies to study the effects of ubiquitination and describe an additional novel approach that we have developed.
Collapse
Affiliation(s)
- Daniel K Stringer
- Department of Molecular Physiology and Biophysics; University of Iowa; Iowa City, IA, USA
| | | |
Collapse
|
99924
|
Li Y, Yu Y, Zhang Y, Zhou Y, Li C, Zhu J, Yuan H, Lu H. MAFIP is a tumor suppressor in cervical cancer that inhibits activation of the nuclear factor-kappa B pathway. Cancer Sci 2011; 102:2043-50. [DOI: 10.1111/j.1349-7006.2011.02061.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
|
99925
|
Villar J, Cabrera NE, Valladares F, Casula M, Flores C, Blanch L, Quilez ME, Santana-Rodríguez N, Kacmarek RM, Slutsky AS. Activation of the Wnt/β-catenin signaling pathway by mechanical ventilation is associated with ventilator-induced pulmonary fibrosis in healthy lungs. PLoS One 2011; 6:e23914. [PMID: 21935365 PMCID: PMC3174135 DOI: 10.1371/journal.pone.0023914] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 07/27/2011] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Mechanical ventilation (MV) with high tidal volumes (V(T)) can cause or aggravate lung damage, so-called ventilator induced lung injury (VILI). The relationship between specific mechanical events in the lung and the cellular responses that result in VILI remains incomplete. Since activation of Wnt/β-catenin signaling has been suggested to be central to mechanisms of lung healing and fibrosis, we hypothesized that the Wnt/β-catenin signaling plays a role during VILI. METHODOLOGY/PRINCIPAL FINDINGS Prospective, randomized, controlled animal study using adult, healthy, male Sprague-Dawley rats. Animals (n = 6/group) were randomized to spontaneous breathing or two strategies of MV for 4 hours: low tidal volume (V(T)) (6 mL/kg) or high V(T) (20 mL/kg). Histological evaluation of lung tissue, measurements of WNT5A, total β-catenin, non-phospho (Ser33/37/Thr41) β-catenin, matrix metalloproteinase-7 (MMP-7), cyclin D1, vascular endothelial growth factor (VEGF), and axis inhibition protein 2 (AXIN2) protein levels by Western blot, and WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, and AXIN2 immunohistochemical localization in the lungs were analyzed. High-V(T) MV caused lung inflammation and perivascular edema with cellular infiltrates and collagen deposition. Protein levels of WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, cyclin D1, VEGF, and AXIN2 in the lungs were increased in all ventilated animals although high-V(T) MV was associated with significantly higher levels of WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, cyclin D1, VEGF, and AXIN2 levels. CONCLUSIONS/SIGNIFICANCE Our findings demonstrate that the Wnt/β-catenin signaling pathway is modulated very early by MV in lungs without preexistent lung disease, suggesting that activation of this pathway could play an important role in both VILI and lung repair. Modulation of this pathway might represent a therapeutic option for prevention and/or management of VILI.
Collapse
Affiliation(s)
- Jesús Villar
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
99926
|
Mammoto T, Mammoto A, Torisawa YS, Tat T, Gibbs A, Derda R, Mannix R, de Bruijn M, Yung CW, Huh D, Ingber DE. Mechanochemical control of mesenchymal condensation and embryonic tooth organ formation. Dev Cell 2011; 21:758-69. [PMID: 21924961 DOI: 10.1016/j.devcel.2011.07.006] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 05/28/2011] [Accepted: 07/11/2011] [Indexed: 12/24/2022]
Abstract
Mesenchymal condensation is critical for organogenesis, yet little is known about how this process is controlled. Here we show that Fgf8 and Sema3f, produced by early dental epithelium, respectively, attract and repulse mesenchymal cells, which cause them to pack tightly together during mouse tooth development. Resulting mechanical compaction-induced changes in cell shape induce odontogenic transcription factors (Pax9, Msx1) and a chemical cue (BMP4), and mechanical compression of mesenchyme is sufficient to induce tooth-specific cell fate switching. The inductive effects of cell compaction are mediated by suppression of the mechanical signaling molecule RhoA, and its overexpression prevents odontogenic induction. Thus, the mesenchymal condensation that drives tooth formation is induced by antagonistic epithelial morphogens that manifest their pattern-generating actions mechanically via changes in mesenchymal cell shape and altered mechanotransduction.
Collapse
Affiliation(s)
- Tadanori Mammoto
- Vascular Biology Program, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
99927
|
Bassard JE, Mutterer J, Duval F, Werck-Reichhart D. A novel method for monitoring the localization of cytochromes P450 and other endoplasmic reticulum membrane associated proteins: a tool for investigating the formation of metabolons. FEBS J 2011; 279:1576-83. [PMID: 21851555 DOI: 10.1111/j.1742-4658.2011.08312.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In plants and possibly other organisms, channelling of the reactive intermediates resulting from P450 oxygenation is thought to require the formation of supramolecular complexes associating membrane-bound and soluble enzymes. This implies a most probably loose membrane association of the soluble proteins. For the assessment of such membrane association in vivo, we propose an imaging strategy based on the accurate evaluation of fluorescent protein repartition and distance around endoplasmic reticulum (ER) tubules. It requires candidate protein fusion constructs with fluorescent reporters and transient expression in leaves of Nicotiana benthamiana. The method was tested with soluble eGFP/mRFP1, with various P450 and P450 reductase fluorescent fusions, and with anchored eGFP/mRFP1. It easily differentiated soluble and anchored proteins and detects subtle changes in ER tubules. The method was further assessed with a soluble protein previously shown to be loosely associated with the ER, the phenylalanine ammonia lyase PAL1 involved in the lignin biosynthetic pathway. This protein was found located in close vicinity to the ER. Taken together, these data indicate that the method proposed herein is suitable to monitor membrane association and relocalization of soluble proteins involved in the formation of metabolons.
Collapse
Affiliation(s)
- Jean-Etienne Bassard
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
| | | | | | | |
Collapse
|
99928
|
Rada P, Doležal P, Jedelský PL, Bursac D, Perry AJ, Šedinová M, Smíšková K, Novotný M, Beltrán NC, Hrdý I, Lithgow T, Tachezy J. The core components of organelle biogenesis and membrane transport in the hydrogenosomes of Trichomonas vaginalis. PLoS One 2011; 6:e24428. [PMID: 21935410 PMCID: PMC3174187 DOI: 10.1371/journal.pone.0024428] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 08/09/2011] [Indexed: 12/02/2022] Open
Abstract
Trichomonas vaginalis is a parasitic protist of the Excavata group. It contains an anaerobic form of mitochondria called hydrogenosomes, which produce hydrogen and ATP; the majority of mitochondrial pathways and the organellar genome were lost during the mitochondrion-to-hydrogenosome transition. Consequently, all hydrogenosomal proteins are encoded in the nucleus and imported into the organelles. However, little is known about the membrane machineries required for biogenesis of the organelle and metabolite exchange. Using a combination of mass spectrometry, immunofluorescence microscopy, in vitro import assays and reverse genetics, we characterized the membrane proteins of the hydrogenosome. We identified components of the outer membrane (TOM) and inner membrane (TIM) protein translocases include multiple paralogs of the core Tom40-type porins and Tim17/22/23 channel proteins, respectively, and uniquely modified small Tim chaperones. The inner membrane proteins TvTim17/22/23-1 and Pam18 were shown to possess conserved information for targeting to mitochondrial inner membranes, but too divergent in sequence to support the growth of yeast strains lacking Tim17, Tim22, Tim23 or Pam18. Full complementation was seen only when the J-domain of hydrogenosomal Pam18 was fused with N-terminal region and transmembrane segment of the yeast homolog. Candidates for metabolite exchange across the outer membrane were identified including multiple isoforms of the β-barrel proteins, Hmp35 and Hmp36; inner membrane MCF-type metabolite carriers were limited to five homologs of the ATP/ADP carrier, Hmp31. Lastly, hydrogenosomes possess a pathway for the assembly of C-tail-anchored proteins into their outer membrane with several new tail-anchored proteins being identified. These results show that hydrogenosomes and mitochondria share common core membrane components required for protein import and metabolite exchange; however, they also reveal remarkable differences that reflect the functional adaptation of hydrogenosomes to anaerobic conditions and the peculiar evolutionary history of the Excavata group.
Collapse
Affiliation(s)
- Petr Rada
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Pavel Doležal
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Petr L. Jedelský
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
- Laboratory of Mass Spectrometry, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Dejan Bursac
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Australia
| | - Andrew J. Perry
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Australia
| | - Miroslava Šedinová
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Kateřina Smíšková
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Marian Novotný
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Neritza Campo Beltrán
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Ivan Hrdý
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Trevor Lithgow
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Australia
| | - Jan Tachezy
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
- * E-mail:
| |
Collapse
|
99929
|
Abstract
Cells recognize external chemical gradients and translate these environmental cues into amplified intracellular signaling that results in elongated cell shape, actin polymerization toward the leading edge, and movement along the gradient. Mechanisms underlying chemotaxis are conserved evolutionarily from Dictyostelium amoeba to mammalian neutrophils. Recent studies have uncovered several parallel intracellular signaling pathways that crosstalk in chemotaxing cells. Here, we review these signaling mechanisms in Dictyostelium discoideum.
Collapse
Affiliation(s)
- Yu Wang
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | | |
Collapse
|
99930
|
Bao ZQ, Jacobsen DM, Young MA. Briefly bound to activate: transient binding of a second catalytic magnesium activates the structure and dynamics of CDK2 kinase for catalysis. Structure 2011; 19:675-90. [PMID: 21565702 DOI: 10.1016/j.str.2011.02.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 01/26/2011] [Accepted: 02/07/2011] [Indexed: 01/14/2023]
Abstract
We have determined high-resolution crystal structures of a CDK2/Cyclin A transition state complex bound to ADP, substrate peptide, and MgF(3)(-). Compared to previous structures of active CDK2, the catalytic subunit of the kinase adopts a more closed conformation around the active site and now allows observation of a second Mg(2+) ion in the active site. Coupled with a strong [Mg(2+)] effect on in vitro kinase activity, the structures suggest that the transient binding of the second Mg(2+) ion is necessary to achieve maximum rate enhancement of the chemical reaction, and Mg(2+) concentration could represent an important regulator of CDK2 activity in vivo. Molecular dynamics simulations illustrate how the simultaneous binding of substrate peptide, ATP, and two Mg(2+) ions is able to induce a more rigid and closed organization of the active site that functions to orient the phosphates, stabilize the buildup of negative charge, and shield the subsequently activated γ-phosphate from solvent.
Collapse
Affiliation(s)
- Zhao Qin Bao
- Department of Biological Chemistry and the Bioinformatics Program, The University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | | |
Collapse
|
99931
|
Serva A, Claas C, Starkuviene V. A Potential of microRNAs for High-Content Screening. J Nucleic Acids 2011; 2011:870903. [PMID: 21922044 PMCID: PMC3172976 DOI: 10.4061/2011/870903] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Revised: 05/15/2011] [Accepted: 06/03/2011] [Indexed: 12/19/2022] Open
Abstract
In the last years miRNAs have increasingly been recognised as potent posttranscriptional regulators of gene expression. Possibly, miRNAs exert their action on virtually any biological process by simultaneous regulation of numerous genes. The importance of miRNA-based regulation in health and disease has inspired research to investigate diverse aspects of miRNA origin, biogenesis, and function. Despite the recent rapid accumulation of experimental data, and the emergence of functional models, the complexity of miRNA-based regulation is still far from being well understood. In particular, we lack comprehensive knowledge as to which cellular processes are regulated by which miRNAs, and, furthermore, how temporal and spatial interactions of miRNAs to their targets occur. Results from large-scale functional analyses have immense potential to address these questions. In this review, we discuss the latest progress in application of high-content and high-throughput functional analysis for the systematic elucidation of the biological roles of miRNAs.
Collapse
Affiliation(s)
- Andrius Serva
- BioQuant, University of Heidelberg, 69120 Heidelberg, Germany
| | | | | |
Collapse
|
99932
|
Zhou J, Wang H, Cannon V, Wolcott KM, Song H, Yates C. Side population rather than CD133(+) cells distinguishes enriched tumorigenicity in hTERT-immortalized primary prostate cancer cells. Mol Cancer 2011; 10:112. [PMID: 21917149 PMCID: PMC3180433 DOI: 10.1186/1476-4598-10-112] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/14/2011] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Subpopulations of cancer cells with the capacity of generating solid tumors have been characterized. In various cancer types, including prostate cancer cells, a side population (SP) and CD133-expressing cells have been proposed as containing a population cancer cells with stem-like ability. Therefore the aim of this work was to determine, in prostate cancer cell lines, the frequency and tumorigenic potential of SP and CD133+ cells. RESULTS In vitro 2D colony-forming assay and sphere-forming assay, Flow cytometry analysis and magnetic cell sorting were utilized to sort CD133+, CD133- and Side population (SP) cells. Our findings indicate that CD44 and integrin α-6 are uniformly expressed in the hTERT cell lines; however, CD133 is expressed only in a small population (< 0.1%). FACS-sorted CD133+ and CD133- cells exhibited similar tumorigenicity in vitro and in vivo. Additionally, for the hTERT cells, SP rather than CD133 expression showed an 8-fold enhanced tumorigenic potential. The data suggest that SP cells, rather than those with CD133 marker, contain the rare population of CSC capable of producing prostate tumors. CONCLUSION Collectively, our data suggest that although CD133 is expressed only in a small population of hTERT-immortalized prostate cancer cells, it is not likely to be associated with stem cells, as CD133- and CD133+ cells exhibited similar tumorigenicity. However, SP isolated cells, appear to be enriched with tumorigenic stem-like cells capable of generating palpable tumors.
Collapse
Affiliation(s)
- Jianjun Zhou
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA
| | | | | | | | | | | |
Collapse
|
99933
|
Abstract
Peptide loading of MHC class II (MHCII) molecules is catalyzed by the nonclassical MHCII-related molecule H2-M. H2-O, another MHCII-like molecule, associates with H2-M and modulates H2-M function. The MHCII presentation pathway is tightly regulated in dendritic cells (DCs), yet how the key modulators of MHCII presentation, H2-M and H2-O, are affected in different DC subsets in response to maturation is unknown. In this study, we show that H2-O is markedly downregulated in vivo in mouse CD8α(-) DCs in response to a broad array of TLR agonists. In contrast, CD8α(+) DCs only modestly downregulated H2-O in response to TLR agonists. H2-M levels were slightly downmodulated in both CD8α(-) and CD8α(+) DCs. As a consequence, H2-M/H2-O ratios significantly increased for CD8α(-) but not for CD8α(+) DCs. The TLR-mediated downregulation was DC specific, as B cells did not show significant H2-O and H2-M downregulation. TLR4 signaling was required to mediate DC H2-O downregulation in response to LPS. Finally, our studies showed that the mechanism of H2-O downregulation was likely due to direct protein degradation of H2-O as well as downregulation of H2-O mRNA levels. The differential H2-O and H2-M modulation after DC maturation supports the proposed roles of CD8α(-) DCs in initiating CD4-restricted immune responses by optimal MHCII presentation and of CD8α(+) DCs in promoting immune tolerance via presentation of low levels of MHCII-peptide.
Collapse
Affiliation(s)
- Gavin W Porter
- Immunology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | | | | |
Collapse
|
99934
|
Abstract
Recent research on hematological malignancies has shown that malignant cells often co-opt physiological pathways to promote their growth and development. Bone marrow homeostasis requires a fine balance between cellular differentiation and self-renewal; cell survival and apoptosis; and cellular proliferation and senescence. The Ras/Raf/MEK/ERK pathway has been shown to be important in regulating these biological functions. Moreover, the Ras/Raf/MEK/ERK pathway has been estimated to be mutated in 30% of all cancers, thus making it the focus of many scientific studies which have lead to a deeper understanding of cancer development and help to elucidate potential weaknesses that can be targeted by pharmacological agents [1]. In this review, we specifically focus on the role of this pathway in physiological hematopoiesis and how augmentation of the pathway may lead to hematopoietic malignancies. We also discuss the challenges and success of targeting this pathway.
Collapse
Affiliation(s)
- Eva Chung
- Department of Immunology, Duke University Medical Center, 101 Jones Building, DUMC Box 3010, Research Drive, Durham, NC 27710, USA
| | | |
Collapse
|
99935
|
Conradi J, Huber S, Gaus K, Mertink F, Royo Gracia S, Strijowski U, Backert S, Sewald N. Cyclic RGD peptides interfere with binding of the Helicobacter pylori protein CagL to integrins αVβ3 and α5β1. Amino Acids 2011; 43:219-32. [PMID: 21915696 DOI: 10.1007/s00726-011-1066-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 08/25/2011] [Indexed: 12/14/2022]
Abstract
The human pathogen Helicobacter pylori that may cause different gastric diseases exploits integrins for infection of gastric cells. The H. pylori protein CagL present on the outer region of the type IV secretion pilus contains an RGD sequence (-Arg-Gly-Asp-) that enables binding to cells presenting integrins α5β1 and αVβ3. This interaction can be inhibited with conformationally designed cyclic RGD peptides derived from the CagL epitope -Ala-Leu-Arg-Gly-Asp-Leu-Ala-. The inhibition of the CagL-αVβ3 interaction by different RGD peptides strongly suggests the importance of the RGD motif for CagL binding. CagL point mutants (RAD, RGA) show decreased affinity to integrin αVβ3. Furthermore, structure-activity relationship studies with cyclic RGD peptides in a spatial screening approach show the distinct influence of the three-dimensional arrangement of RGD motif on the ability to interfere with this interaction. Resulting from these studies, similar structural requirements for the CagL epitope as previously suggested for other ligands of integrin αVβ3 are proposed.
Collapse
Affiliation(s)
- Jens Conradi
- Department of Chemistry, Bielefeld University, Universitätsstraße 25, PO Box 10 01 31, 33501, Bielefeld, Germany
| | | | | | | | | | | | | | | |
Collapse
|
99936
|
Affiliation(s)
- Diego Romero
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | - Matthew F. Traxler
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | | | - Roberto Kolter
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| |
Collapse
|
99937
|
Abstract
Numb regulates endocytosis in many metazoans, but the mechanism by which it functions is not completely understood. Here we report that the Caenorhabditis elegans Numb ortholog, NUM-1A, a regulator of endocytic recycling, binds the C isoform of transbilayer amphipath transporter-1 (TAT-1), a P4 family adenosine triphosphatase and putative aminophospholipid translocase that is required for proper endocytic trafficking. We demonstrate that TAT-1 is differentially spliced during development and that TAT-1C-specific splicing occurs in the intestine where NUM-1A is known to function. NUM-1A and TAT-1C colocalize in vivo. We have mapped the binding site to an NXXF motif in TAT-1C. This motif is not required for TAT-1C function but is required for NUM-1A's ability to inhibit recycling. We demonstrate that num-1A and tat-1 defects are both suppressed by the loss of the activity of PSSY-1, a phosphatidylserine (PS) synthase. PS is mislocalized in intestinal cells with defects in tat-1 or num-1A function. We propose that NUM-1A inhibits recycling by inhibiting TAT-1C's ability to translocate PS across the membranes of recycling endosomes.
Collapse
Affiliation(s)
- Lars Nilsson
- Umeå Center for Molecular Medicine, Umeå University, SE-901 87 Umeå, Sweden
| | | | | |
Collapse
|
99938
|
Abstract
Yeast cells approach a mating partner by polarizing along a gradient of mating pheromones that are secreted by cells of the opposite mating type. The Bar1 protease is secreted by a-cells and, paradoxically, degrades the α-factor pheromones which are produced by cells of the opposite mating type and trigger mating in a-cells. This degradation may assist in the recovery from pheromone signaling but has also been shown to play a positive role in mating. Previous studies suggested that widely diffusing protease can bias the pheromone gradient towards the closest secreting cell. Here, we show that restricting the Bar1 protease to the secreting cell itself, preventing its wide diffusion, facilitates discrimination between equivalent mating partners. This may be mostly relevant during spore germination, where most mating events occur in nature.
Collapse
Affiliation(s)
- Noa Rappaport
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100 Israel
| | | |
Collapse
|
99939
|
Teske BF, Wek SA, Bunpo P, Cundiff JK, McClintick JN, Anthony TG, Wek RC. The eIF2 kinase PERK and the integrated stress response facilitate activation of ATF6 during endoplasmic reticulum stress. Mol Biol Cell 2011; 22:4390-405. [PMID: 21917591 PMCID: PMC3216664 DOI: 10.1091/mbc.e11-06-0510] [Citation(s) in RCA: 271] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
This study shows that the eIF2 kinase PERK is required not only for translational control but also for activation of ATF6 and its target genes in the unfolded protein response. The PERK pathway facilitates both the synthesis of ATF6 and trafficking of ATF6 from the endoplasmic reticulum to the Golgi for intramembrane proteolysis and activation of ATF6. Disruptions of the endoplasmic reticulum (ER) that perturb protein folding cause ER stress and elicit an unfolded protein response (UPR) that involves translational and transcriptional changes in gene expression aimed at expanding the ER processing capacity and alleviating cellular injury. Three ER stress sensors (PERK, ATF6, and IRE1) implement the UPR. PERK phosphorylation of the α subunit of eIF2 during ER stress represses protein synthesis, which prevents further influx of ER client proteins. Phosphorylation of eIF2α (eIF2α∼P) also induces preferential translation of ATF4, a transcription activator of the integrated stress response. In this study we show that the PERK/eIF2α∼P/ATF4 pathway is required not only for translational control, but also for activation of ATF6 and its target genes. The PERK pathway facilitates both the synthesis of ATF6 and trafficking of ATF6 from the ER to the Golgi for intramembrane proteolysis and activation of ATF6. As a consequence, liver-specific depletion of PERK significantly reduces both the translational and transcriptional phases of the UPR, leading to reduced protein chaperone expression, disruptions of lipid metabolism, and enhanced apoptosis. These findings show that the regulatory networks of the UPR are fully integrated and help explain the diverse biological defects associated with loss of PERK.
Collapse
Affiliation(s)
- Brian F Teske
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | | | | | | | | | | |
Collapse
|
99940
|
Sillo A, Matthias J, Konertz R, Bozzaro S, Eichinger L. Salmonella typhimurium is pathogenic for Dictyostelium cells and subverts the starvation response. Cell Microbiol 2011; 13:1793-811. [PMID: 21824247 DOI: 10.1111/j.1462-5822.2011.01662.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In unicellular amoebae, such as Dictyostelium discoideum, bacterial phagocytosis is a food hunting device, while in higher organisms it is the first defence barrier against microbial infection. In both cases, pathogenic bacteria exploit phagocytosis to enter the cell and multiply intracellularly. Salmonella typhimurium, the agent of food-borne gastroenteritis, is phagocytosed by both macrophages and Dictyostelium cells. By using cell biological assays and global transcriptional analysis with DNA microarrays covering the Dictyostelium genome, we show here that S. typhimurium is pathogenic for Dictyostelium cells. Depending on the degree of virulence, which in turn depended on bacterial growth conditions, Salmonella could kill Dictyostelium cells or inhibit their growth and development. In the early phase of infection in non-nutrient buffer, the ingested bacteria escaped degradation, induced a starvation-like transcriptional response but inhibited selectively genes required for chemotaxis and aggregation. This way differentiation of the host cells into spore and stalk cells was blocked or delayed, which in turn is likely to be favourable for the establishment of a replicative niche for Salmonella. Inhibition of the aggregation competence and chemotactic streaming of aggregation-competent cells in the presence of Salmonella suggests interference with cAMP signalling.
Collapse
Affiliation(s)
- Alessio Sillo
- Department of Clinical and Biological Sciences, University of Turin, AOU S. Luigi, 10043 Orbassano (Torino), Italy
| | | | | | | | | |
Collapse
|
99941
|
Abstract
Integrin adhesion receptors are essential for the normal function of most multicellular organisms, and defective integrin activation or integrin signaling is associated with an array of pathological conditions. Integrins are regulated by conformational changes, clustering, and trafficking, and regulatory mechanisms differ strongly between individual integrins and between cell types. Whereas integrins in circulating blood cells are activated by an inside-out-induced conformational change that favors high-affinity ligand binding, β1-integrins in adherent cells can be activated by force or clustering. In addition, endocytosis and recycling play an important role in the regulation of integrin turnover and integrin redistribution in adherent cells, especially during dynamic processes such as cell migration and invasion. Integrin trafficking is strongly regulated by their cytoplasmic tails, and the mechanisms are now being identified.
Collapse
Affiliation(s)
- Coert Margadant
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | | | | | | |
Collapse
|
99942
|
Cabarcas SM, Mathews LA, Farrar WL. The cancer stem cell niche--there goes the neighborhood? Int J Cancer 2011; 129:2315-27. [PMID: 21792897 DOI: 10.1002/ijc.26312] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 03/07/2011] [Indexed: 12/11/2022]
Abstract
The niche is the environment in which stem cells reside and is responsible for the maintenance of unique stem cell properties such as self-renewal and an undifferentiated state. The heterogeneous populations which constitute a niche include both stem cells and surrounding differentiated cells. This network of heterogeneity is responsible for the control of the necessary pathways that function in determining stem cell fate. The concept that cancer stem cells, a subpopulation of cells responsible for tumor initiation and formation, reside in their own unique niche is quickly evolving and it is of importance to understand and identify the processes occurring within this environment. The necessary intrinsic pathways that are utilized by this cancer stem cell population to maintain both self-renewal and the ability to differentiate are believed to be a result of the environment where cancer stem cells reside. The ability of a specific cancer stem cell niche to provide the environment in which this population can flourish is a critical aspect of cancer biology that mandates intense investigation. This review focuses on current evidence demonstrating that homeostatic processes such as inflammation, epithelial to mesenchymal transition, hypoxia and angiogenesis contribute to the maintenance and control of cancer stem cell fate by providing the appropriate signals within the microenvironment. It is necessary to understand the key processes occurring within this highly specialized cancer stem cell niche to identify potential therapeutic targets that can serve as the basis for development of more effective anticancer treatments.
Collapse
Affiliation(s)
- Stephanie M Cabarcas
- Cancer Stem Cell Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | | | | |
Collapse
|
99943
|
Han JK, Kim HL, Jeon KH, Choi YE, Lee HS, Kwon YW, Jang JJ, Cho HJ, Kang HJ, Oh BH, Park YB, Kim HS. Peroxisome proliferator-activated receptor-δ activates endothelial progenitor cells to induce angio-myogenesis through matrix metallo-proteinase-9-mediated insulin-like growth factor-1 paracrine networks. Eur Heart J 2011; 34:1755-65. [PMID: 21920965 DOI: 10.1093/eurheartj/ehr365] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AIMS The roles of peroxisome proliferator-activated receptor (PPAR)-δ in vascular biology are mainly unknown. We investigated the effects of PPAR-δ activation on the paracrine networks between endothelial progenitor cells (EPCs) and endothelial cells (ECs)/skeletal muscle. METHODS AND RESULTS Treatment of EPCs with GW501516, a PPAR-δ agonist, induced specifically matrix metallo-proteinase (MMP)-9 by direct transcriptional activation. Subsequently, this increased-MMP-9 broke down insulin-like growth factor-binding protein (IGFBP)-3, resulting in IGF-1 receptor (IGF-1R) activation in surrounding target cells. Treatment of conditioned medium from GW501516-stimulated EPCs enhanced the number and functions of human umbilical vein ECs and C2C12 myoblasts via MMP-9-mediated IGF-1R activation. Systemic administration of GW501516 in mice increased MMP-9 expression in EPCs, and augmented IGFBP-3 degradation in serum. In a mouse hindlimb ischaemia model, systemic treatment of GW501516 or local transplantation of GW501516-treated EPCs induced IGF-1R phosphorylation in ECs and skeletal muscle in the ischaemic limbs, leading to augmented angiogenesis and skeletal muscle regeneration. It also enhanced wound healing with increased angiogenesis in a mouse skin punch wound model. These pro-angiogenic and muscle-regenerating effects were abolished by MMP-9 knock-out. CONCLUSION Our results suggest that PPAR-δ is a crucial modulator of angio-myogenesis via the paracrine effects of EPCs, and its agonist is a good candidate as a therapeutic drug for patients with peripheral vascular diseases.
Collapse
Affiliation(s)
- Jung-Kyu Han
- National Research Laboratory for Cardiovascular Stem Cell, Seoul National University College of Medicine, Seoul, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
99944
|
Poukkula M, Kremneva E, Serlachius M, Lappalainen P. Actin-depolymerizing factor homology domain: a conserved fold performing diverse roles in cytoskeletal dynamics. Cytoskeleton (Hoboken) 2011; 68:471-90. [PMID: 21850706 DOI: 10.1002/cm.20530] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 06/29/2011] [Accepted: 08/05/2011] [Indexed: 11/09/2022]
Abstract
Actin filaments form contractile and protrusive structures that play central roles in many processes such as cell migration, morphogenesis, endocytosis, and cytokinesis. During these processes, the dynamics of the actin filaments are precisely regulated by a large array of actin-binding proteins. The actin-depolymerizing factor homology (ADF-H) domain is a structurally conserved protein motif, which promotes cytoskeletal dynamics by interacting with monomeric and/or filamentous actin, and with the Arp2/3 complex. Despite their structural homology, the five classes of ADF-H domain proteins display distinct biochemical activities and cellular roles, only parts of which are currently understood. ADF/cofilin promotes disassembly of aged actin filaments, whereas twinfilin inhibits actin filament assembly via sequestering actin monomers and interacting with filament barbed ends. GMF does not interact with actin, but instead binds Arp2/3 complex and promotes dissociation of Arp2/3-mediated filament branches. Abp1 and drebrin are multidomain proteins that interact with actin filaments and regulate the activities of other proteins during various actin-dependent processes. The exact function of coactosin is currently incompletely understood. In this review article, we discuss the biochemical functions, cellular roles, and regulation of the five groups of ADF-H domain proteins.
Collapse
Affiliation(s)
- Minna Poukkula
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Finland
| | | | | | | |
Collapse
|
99945
|
Affiliation(s)
- Catherine R Paschal
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | | |
Collapse
|
99946
|
Poeck B, Strauss R, Kretzschmar D. Analysis of amyloid precursor protein function in Drosophila melanogaster. Exp Brain Res 2012; 217:413-21. [PMID: 21912928 DOI: 10.1007/s00221-011-2860-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 08/30/2011] [Indexed: 10/17/2022]
Abstract
Amyloid precursor proteins (APPs) are evolutionary conserved from nematodes to man (Jacobsen and Iverfeldt in Cell Mol Life Sci 66:2299-2318, 2009) suggesting an important physiological function of these proteins. Human APP is a key factor in the pathogenesis of Alzheimer's Disease because its proteolytic processing results in the production of the neurotoxic Aβ-peptide, which accumulates in the amyloid plaques characteristic for this disease (Selkoe in Physiol Rev 81(2):741-766, 2001). However, the processing also leads to the production of several other fragments and the role of these products, as well as the function of the full-length protein is so far not well understood. The functional analysis of APP in vertebrates has been hampered by the fact that two close relatives, APLP1 and APLP2, exist and that knock-out mice for APP only show subtle defects. In contrast, invertebrates like Caenorhabditis elegans and Drosophila express only one APP-like protein but whereas a null mutation in the C. elegans APL-1 protein is lethal, flies lacking APPL (Amyloid Precursor Protein-like) are viable but show synaptic defects and behavioral abnormalities. Together with the analyses of flies that express APP proteins ectoptically or xenotopically, these studies show that APP proteins are involved in neuronal differentiation, neuritic outgrowth, and synapse formation. In addition, they play a role in long-term memory formation and maintaining brain integrity in adult flies.
Collapse
|
99947
|
Kim KS, Lee YA, Choi HM, Yoo MC, Yang HI. Implication of MMP-9 and urokinase plasminogen activator (uPA) in the activation of pro-matrix metalloproteinase (MMP)-13. Rheumatol Int 2011; 32:3069-75. [PMID: 21913037 DOI: 10.1007/s00296-011-2095-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 08/21/2011] [Indexed: 10/17/2022]
Abstract
We examined whether the expression and activation of pro-matrix metalloproteinase (MMP)-1 varies from that of pro-MMP-13 in the joint fluid of osteoarthritis (OA) and rheumatoid arthritis (RA) patients. To do this, joint fluid was collected from 34 RA and 34 OA patients. The collagenase (pro-MMP-1 and MMP-13, total MMP-1, and MMP-13), gelatinase (total MMP-2 and MMP-9), stromelysin (total MMP-3), matrilysin (total MMP-7), uPA, and tissue inhibitor of MMP (TIMP) levels were measured by ELISA. The level of total MMP-1 in RA joint fluids was similar to that of the OA joint fluid. In contrast, the level of total MMP-13 in the RA group was significantly higher than that of the OA group. Among various MMPs (MMP-2, MMP-3, MMP-7, and MMP-9), only MMP-9 was strongly associated with total MMP-13 in both RA and OA. The level of uPA was also strongly associated with MMP-13 in RA but not OA, while the level of TIMP-1 and TIMP-2 was not significantly different between RA and OA. In conclusion, MMP-9 and uPA might be involved in the activation of pro-MMP-13 through unknown mechanisms in arthritic diseases.
Collapse
Affiliation(s)
- Kyoung Soo Kim
- East-West Bone and Joint Research Institute, Kyung Hee University Hospital at KANGDONG, 149 Sangil-dong, Gangdong-gu, Seoul 134-727, Republic of Korea.
| | | | | | | | | |
Collapse
|
99948
|
Matern O, Sauleau EA, Tschill P, Perrin-Schmitt F, Grollemund B. Left-sided predominance of hypodontia irrespective of cleft sidedness in a French population. Cleft Palate Craniofac J 2011; 49:e1-5. [PMID: 21905908 DOI: 10.1597/11-025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE Individuals with oral clefts exhibit considerably more dental anomalies than do individuals without clefts. Our aim was to evaluate the prevalence of tooth agenesis in a sample composed of 124 children (81 boys and 43 girls, mean age 12.5 years) with clefts registered with the Cleft Palate Center in Strasbourg (France). DESIGN Cleft types and dental agenesis were assessed by clinical and radiographic examination. Cleft types were divided into four groups according to the clinical extent of the cleft (cleft lip only [CL, 12.9%], cleft lip and alveolus [CLA, 4%], cleft lip and palate [CLP, 49.2%], and cleft palate only [CP, 33.9%]). RESULTS Of the subjects 63% had evidence of hypodontia: maxillary lateral incisors (54%) and upper and lower premolars (32%) were the most common missing teeth. The number of dental ageneses associated with CP (54%) and CLP (79%) was significantly higher than that with CL (33%). All these anomalies were found in proportionately higher frequencies as the severity of the cleft increased, and we found left side predominance for hypodontia (p < .01) irrespective of cleft sidedness. CONCLUSIONS Both right-sided and left-sided clefts were more frequently correlated with left-sided dental agenesis. This left-sided prevalence suggests that common signaling malfunctions might be involved, both in dental development anomalies and cleft genesis.
Collapse
Affiliation(s)
- Olivier Matern
- Pôle de médecine et Chirurgie bucco-dentaires, Unité Fonctionnelle d'Orthopédie Dento-Faciale, 1, Place de l'Hôpital - 67091 Strasbourg, France.
| | | | | | | | | |
Collapse
|
99949
|
Abstract
The MYC/MAX/MAD network is of central importance for controlling cell physiology. The network is compiled of transcriptional regulators that form different heterodimers, which can either activate or repress the expression of target genes. Thus these proteins function as a molecular switch to control gene expression. MAD1, a member of this network, acts as a transcriptional repressor. It interacts with MAX to form the OFF position of the switch, antagonizing MYC/MAX complexes that define the ON position. MAD1 regulates cell proliferation and apoptosis through a number of target genes. In addition recent evidence indicates that the expression and activity of MAD1 are regulated at multiple levels. Here the recent developments are summarized, in comparison to MYC, of our understanding how the expression of the MAD1 gene and protein are controlled and what the functional consequences and downstream effectors of MAD1 are, which relay its activity as a transcriptional regulator.
Collapse
Affiliation(s)
- Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, 52057 Aachen, Germany.
| |
Collapse
|
99950
|
Abstract
Rhabdomyosarcoma (RMS) is a morphologically and clinically heterogeneous group of malignant tumors that resemble developing skeletal muscle and is the most common soft-tissue sarcoma in children and adolescents. The most prominent sites involve head and neck structures (~40%), genito-urinary track (~25%), and extremities (~20%). Embryonal (ERMS) and alveolar (ARMS) are the two major RMS subtypes that are distinct in their morphology and genetic make-up. The prognosis for this cancer depends strongly on tumor size, location, staging, and child's age. In general, ERMS has a more favorable outcome, whereas the mortality rate remains high in patients with ARMS, because of its aggressive and metastatic nature. Over the past two decades, researchers have made concerted efforts to delineate genetic and epigenetic changes associated with RMS pathogenesis. These molecular signatures have presented golden opportunities to design targeted therapies for treating this aggressive cancer. This article highlights recent advances in understanding the molecular pathogenesis of RMS, and addresses promising research areas for further exploration.
Collapse
Affiliation(s)
- C Wang
- Department of Oral Biology and Center for Molecular Biology of Oral Diseases, University of Illinois at Chicago, 801 South Paulina Street, RM530CB, m/c 860, Chicago, IL 60612, USA.
| |
Collapse
|