March 12th, 2010 / No Comments » / by Hughes SC, Formstecher E, Fehon RG
Sip1, the Drosophila orthologue of EBP50/NHERF1, functions with the sterile 20 family kinase Slik to regulate Moesin activity.
J Cell Sci. 2010 Mar 9;
Authors: Hughes SC, Formstecher E, Fehon RG
Organization of the plasma membrane in polarized epithelial cells is accomplished by the specific localization of transmembrane or membrane-associated proteins, which are often linked to cytoplasmic protein complexes, including the actin cytoskeleton. In this study, we identified Sip1 as a Drosophila orthologue of the ezrin-radixin-moesin (ERM binding protein 50 (EBP50; also known as the Na(+)/H(+) exchanger regulatory factor NHERF1. In mammals, EBP50/NHERF1 is a scaffold protein required for the regulation of several transmembrane receptors and downstream signal transduction activity. In Drosophila, loss of Sip1 leads to a reduction in Slik kinase protein abundance, loss of Moesin phosphorylation and changes in epithelial structure, including mislocalization of E-cadherin and F-actin. Consistent with these findings, Moesin and Sip1 act synergistically in genetic-interaction experiments, and Sip1 protein abundance is dependent on Moesin. Co-immunoprecipitation experiments indicate that Sip1 forms a complex with both Moesin and Slik. Taken together, these data suggest that Sip1 promotes Slik-dependent phosphorylation of Moesin, and suggests a mechanism for the regulation of Moesin activity within the cell to maintain epithelial integrity.
PMID: 20215404 [PubMed - as supplied by publisher]
Posted in: J Cell Sci
March 12th, 2010 / No Comments » / by pubmed
101 new pubmed citations were retrieved for your search.
Click on the search hyperlink below to display the complete search results:
autoimmune
These pubmed results were generated on 2010/03/12
PubMed, a service of the National Library of Medicine, includes over 15 million
citations for biomedical articles back to the 1950's.
These citations are from MEDLINE and additional life science journals.
PubMed includes links to many sites providing full text articles and other related resources.
Posted in: Report
March 11th, 2010 / No Comments » / by Kumar D, Viberg J, Nilsson AK, Chabes A
Highly mutagenic and severely imbalanced dNTP pools can escape detection by the S-phase checkpoint.
Nucleic Acids Res. 2010 Mar 9;
Authors: Kumar D, Viberg J, Nilsson AK, Chabes A
A balanced supply of deoxyribonucleoside triphosphates (dNTPs) is one of the key prerequisites for faithful genome duplication. Both the overall concentration and the balance among the individual dNTPs (dATP, dTTP, dGTP, and dCTP) are tightly regulated, primarily by the enzyme ribonucleotide reductase (RNR). We asked whether dNTP pool imbalances interfere with cell cycle progression and are detected by the S-phase checkpoint, a genome surveillance mechanism activated in response to DNA damage or replication blocks. By introducing single amino acid substitutions in loop 2 of the allosteric specificity site of Saccharomyces cerevisiae RNR, we obtained a collection of strains with various dNTP pool imbalances. Even mild dNTP pool imbalances were mutagenic, but the mutagenic potential of different dNTP pool imbalances did not directly correlate with their severity. The S-phase checkpoint was activated by the depletion of one or several dNTPs. In contrast, when none of the dNTPs was limiting for DNA replication, even extreme and mutagenic dNTP pool imbalances did not activate the S-phase checkpoint and did not interfere with the cell cycle progression.
PMID: 20215435 [PubMed - as supplied by publisher]
Posted in: Nucleic Acids Res
March 11th, 2010 / No Comments » / by Kavlie RG, Kernan MJ, Eberl DF
Hearing in Drosophila Requires TilB, a Conserved Protein Associated with Ciliary Motility.
Genetics. 2010 Mar 9;
Authors: Kavlie RG, Kernan MJ, Eberl DF
Cilia were present in the earliest eukaryotic ancestor and underlie many biological processes ranging from cell motility and propulsion of extracellular fluids to sensory physiology. We investigated the contribution of the touch insensitive larva B (tilB) gene to cilia function in Drosophila melanogaster. Mutants of tilB exhibit dysfunction in sperm flagella and ciliated dendrites of chordotonal organs that mediate hearing and larval touch sensitivity. Mutant sperm axonemes as well as sensory neuron dendrites of Johnston's organ, the fly's auditory organ, lack dynein arms. Through deficiency mapping and sequencing candidate genes, we identified tilB mutations in the annotated gene CG14620. A genomic CG14620 transgene rescued deafness and male sterility of tilB mutants. TilB is a 395 amino acid protein with a conserved N-terminal leucine-rich-repeat region at residues 16-164 and a coiled-coil domain at residues 171-191. A tilB-Gal4 transgene driving fluorescently tagged TilB proteins elicits cytoplasmic expression in embryonic chordotonal organs, in Johnston's organ, and in sperm flagella. TilB does not appear to affect tubulin polyglutamylation or polyglycylation. The phenotypes and expression of tilB indicate function in cilia construction or maintenance, but not in intraflagellar transport. This is also consistent with phylogenetic association of tilB homologs with presence of genes encoding axonemal dynein arm components. Further elucidation of tilB functional mechanisms will provide greater understanding of cilia function and will facilitate understanding ciliary diseases.
PMID: 20215474 [PubMed - as supplied by publisher]
Posted in: Genetics
March 11th, 2010 / No Comments » / by Ikeda T
NDP kinase 7 is a conserved microtubule-binding protein preferentially expressed in ciliated cells.
Cell Struct Funct. 2010 Mar 10;
Authors: Ikeda T
Nucleoside diphosphate (NDP) kinase is an enzyme that synthesizes the nucleoside triphosphates. In mammals, nine sequences (NDK1-NDK9) have been found with domain(s) homologous to the catalytic domain of NDP kinase, and some of their products have been shown to associate with sperm flagella. The present study examines the localization of NDK7, for which little information has been available. Database analysis showed that the NDK7 gene is present in organisms with cilia and flagella. Western blotting analyses of various mouse tissues consistently indicated that NDK7 is preferentially expressed in tissues with motile cilia as well as in sperm. Immunofluorescence microscopy revealed that this protein is localized along the entire length of the TritonX-100-insoluble fraction of sperm flagella, possibly in the axonemes. Unexpectedly, however, NDK7 in tracheal epithelia was found in the cell body but not in cilia. Finally, in vitro co-sedimentation assays using recombinant proteins showed that both mouse and Chlamydomonas NDK7 directly bind to microtubules.
PMID: 20215702 [PubMed - as supplied by publisher]
Posted in: Cell Struct Funct
March 11th, 2010 / No Comments » / by Jerka-Dziadosz M, Gogendeau D, Klotz C, Cohen J, Beisson J, Koll F
Basal body duplication in Paramecium: The key role of Bld10 in assembly and stability of the cartwheel.
Cytoskeleton. 2010 Mar;67(3):161-71
Authors: Jerka-Dziadosz M, Gogendeau D, Klotz C, Cohen J, Beisson J, Koll F
Basal bodies which nucleate cilia and flagella, and centrioles which organize centrosomes share the same architecture characterized by the ninefold symmetry of their microtubular shaft. Among the conserved proteins involved in the biogenesis of the canonical 9-triplet centriolar structures, Sas-6 and Bld10 proteins have been shown to play central roles in the early steps of assembly and in establishment/stabilization of the ninefold symmetry. Using fluorescent tagged proteins and RNAi to study the localization and function of these two proteins in Paramecium, we focused on the early effects of their depletion, the consequences of their overexpression and their functional interdependence. We find that both genes are essential and their depletion affects cartwheel assembly and hence basal body duplication. We also show that, contrary to Sas6p, Bld10p is not directly responsible for the establishment of the ninefold symmetry, but is required not only for new basal body assembly and stability but also for Sas6p maintenance at mature basal bodies. Finally, ultrastructural analysis of cells overexpressing either protein revealed two types of early assembly intermediates, hub-like structures and generative discs, suggesting a conserved scaffolding process. (c) 2010 Wiley-Liss, Inc.
PMID: 20217679 [PubMed - in process]
Posted in: Cytoskeleton
March 11th, 2010 / No Comments » / by pubmed
347 new pubmed citations were retrieved for your search.
Click on the search hyperlink below to display the complete search results:
kinase
These pubmed results were generated on 2010/03/11
PubMed, a service of the National Library of Medicine, includes over 15 million
citations for biomedical articles back to the 1950's.
These citations are from MEDLINE and additional life science journals.
PubMed includes links to many sites providing full text articles and other related resources.
Posted in: Report
March 11th, 2010 / No Comments » / by pubmed
16 new pubmed citations were retrieved for your search.
Click on the search hyperlink below to display the complete search results:
cancer and mitochondria
These pubmed results were generated on 2010/03/11
PubMed, a service of the National Library of Medicine, includes over 15 million
citations for biomedical articles back to the 1950's.
These citations are from MEDLINE and additional life science journals.
PubMed includes links to many sites providing full text articles and other related resources.
Posted in: Report
March 11th, 2010 / No Comments » / by Xia D, Holla VR, Wang D, Menter DG, Dubois RN
HEF1 is a crucial mediator of the proliferative effects of prostaglandin E(2) on colon cancer cells.
Cancer Res. 2010 Jan 15;70(2):824-31
Authors: Xia D, Holla VR, Wang D, Menter DG, DuBois RN
Prostaglandin E(2) (PGE(2)), one of the downstream products of cyclooxygenase-2 enzymatic activity, promotes colorectal carcinogenesis in part by stimulating cell division. In this study, we define a critical mechanism in this process by showing that the prometastatic adapter protein human enhancer of filamentation 1 (HEF1; NEDD9) links PGE(2) to the cell cycle machinery in colorectal cancer cells. PGE(2) rapidly induced expression of HEF1 mRNA and protein in colorectal cancer cells. HEF1 overexpression elicited the same effects as PGE(2) treatment on cell proliferation, cell cycle progression, and tumor growth. Conversely, HEF1 knockdown suppressed PGE(2)-driven cell proliferation and cell cycle progression. Cell cycle alterations involved HEF1 fragmentation as well as co-distribution of HEF1 and cell cycle kinase Aurora A along spindle asters during cell division. Moreover, Aurora A co-immunoprecipitated with HEF1 and was activated by HEF1. Consistent with a role for HEF1 in colorectal carcinogenesis, we found elevated expression of HEF1 expression in 50% of human colorectal cancers examined, relative to paired normal tissues. These findings establish that PGE(2) induces HEF1 expression, which in turn promotes cell cycle progression through its interaction with and activation of Aurora A. Further, they establish that HEF1 is a crucial downstream mediator of PGE(2) action during colorectal carcinogenesis.
PMID: 20068165 [PubMed - indexed for MEDLINE]
Posted in: Cancer Res
March 10th, 2010 / No Comments » / by McLellan J, O'Neil N, Tarailo S, Stoepel J, Bryan J, Rose A, Hieter P
Synthetic lethal genetic interactions that decrease somatic cell proliferation in Caenorhabditis elegans identify the alternative RFC CTF18 as a candidate cancer drug target.
Mol Biol Cell. 2009 Dec;20(24):5306-13
Authors: McLellan J, O'Neil N, Tarailo S, Stoepel J, Bryan J, Rose A, Hieter P
Somatic mutations causing chromosome instability (CIN) in tumors can be exploited for selective killing of cancer cells by knockdown of second-site genes causing synthetic lethality. We tested and statistically validated synthetic lethal (SL) interactions between mutations in six Saccharomyces cerevisiae CIN genes orthologous to genes mutated in colon tumors and five additional CIN genes. To identify which SL interactions are conserved in higher organisms and represent potential chemotherapeutic targets, we developed an assay system in Caenorhabditis elegans to test genetic interactions causing synthetic proliferation defects in somatic cells. We made use of postembryonic RNA interference and the vulval cell lineage of C. elegans as a readout for somatic cell proliferation defects. We identified SL interactions between members of the cohesin complex and CTF4, RAD27, and components of the alternative RFC(CTF18) complex. The genetic interactions tested are highly conserved between S. cerevisiae and C. elegans and suggest that the alternative RFC components DCC1, CTF8, and CTF18 are ideal therapeutic targets because of their mild phenotype when knocked down singly in C. elegans. Furthermore, the C. elegans assay system will contribute to our knowledge of genetic interactions in a multicellular animal and is a powerful approach to identify new cancer therapeutic targets.
PMID: 19846659 [PubMed - indexed for MEDLINE]
Posted in: Mol Biol Cell
