time-lapse-microscopy-of-early-embryogenesis-in-caenorhabditis-elegans

Time-lapse Microscopy of Early Embryogenesis in <em>Caenorhabditis elegans</em>

Caenorhabditis elegans has often been used as a model system in studies of early developmental processes.  The transparency of the 
embryos, the genetic ...

Protein aggregation is a hallmark of several neurodegenerative diseases including Huntington's disease and Parkinson's disease. Proteins containing long, homopolymeric stretches of glutamine are especially prone to form aggregates. It has long been known that the small protein modifier, ubiquitin, localizes to these aggregates. In this report, nematode and cell culture models for polyglutamine aggregation are used to investigate the role of the ubiquitin pathway in protein aggregation.

Ubiquitin conjugating enzymes participate in polyglutamine protein aggregation.

Proteinanh&auml;ufung ist ein Markenzeichen der mehrere Neurodegenerative Krankheiten einschlie&szlig;lich der Huntington-Krankheit und Morbus Parkinson. Proteine mit langen, sind Homopolymeric erstreckt sich von Glutamin besonders anf&auml;llig f&uuml;r Formular-Aggregate. Es ist seit langem bekannt, dass der kleine Protein-Modifizierer, Ubiquitin, um diese Aggregate lokalisiert. In diesem Bericht sind Fadenw&uuml;rmer und Zell-Kultur-Modelle f&uuml;r bei Polyglutamin-Aggregation verwendet, um die Rolle des Ubiquitin-Signalweges in Proteinanh&auml;ufung untersuchen.

Ubiquitin konjugierenenzym Enzyme bei Polyglutamin Proteinanh&auml;ufung teilnehmen.

In sexual reproduction of most animals, the spermatozoon provides DNA and centrioles, together with some cytoplasm and organelles, to the oocyte that is being fertilized. Paternal mitochondria and their genomes are generally eliminated in the embryo by an unknown degradation mechanism. We show that, upon fertilization, a Caenorhabditis elegans spermatozoon triggers the recruitment of autophagosomes within minutes and subsequent paternal mitochondria degradation. Whereas the nematode-specific sperm membranous organelles are ubiquitinated before autophagosome formation, the mitochondria are not. The degradation of both paternal structures and mitochondrial DNA requires an LC3-dependent autophagy. Analysis of fertilized mouse embryos shows the localization of autophagy markers, which suggests that this autophagy event is evolutionarily conserved to prevent both the transmission of paternal mitochondrial DNA to the offspring and the establishment of heteroplasmy.

Postfertilization autophagy of sperm organelles prevents paternal mitochondrial DNA transmission.

Sexuelle Reproduktion von den meisten Tieren bietet das Spermium DNA und Centrioles, zusammen mit einigen Zytoplasma und Organellen, zu der Eizelle, die befruchtet wird, ist. V&auml;terliche Mitochondrien und ihre Genome werden im Allgemeinen durch einen unbekannten Abbau-Mechanismus im Embryo eliminiert. Wir zeigen, dass bei der Befruchtung, l&ouml;st ein Caenorhabditis Elegans Spermium die Rekrutierung von Autophagosomes innerhalb von Minuten und die Verschlechterung der nachfolgenden v&auml;terliche Mitochondrien. W&auml;hrend die Fadenw&uuml;rmer-spezifische Sperma membran&ouml;se Organellen Ubiquitinated vor Autophagosomen Entstehung, sind die Mitochondrien nicht. Der Abbau der v&auml;terlichen Strukturen und mitochondriale DNA erfordert ein LC3-abh&auml;ngige Autophagy in Verbindung. Analyse der befruchteten Maus Embryonen zeigt die Lokalisierung Autophagy Marker, was darauf hindeutet, dass dieses Ereignis Autophagy evolution&auml;r konserviert wird, um die &Uuml;bermittlung der v&auml;terlichen mitochondrialen DNA an die Nachkommen und die Einrichtung der Heteroplasmie zu verhindern.

Postfertilization Autophagy von Spermien Organellen verhindert v&auml;terlicherseits mitochondriale DNA-&Uuml;bertragung.

The RING finger motif exists in E3 ligases of the ubiquitination pathway. These ubiquitin ligases bind to target proteins, leading to their modification by covalent addition of ubiquitin peptides. Current databases contain hundreds of proteins with RING finger motifs. This study investigates the role of RING finger genes in embryogenesis of the nematode, Caenorhabditis elegans. We expand the previous list of RING finger-containing genes and show that there are 103 RING finger-containing genes in the C. elegans genome. DNA microarrays of these 103 genes were probed with various RNA samples to identify 16 RING finger genes whose expression is enriched in the germline. RNA interference (RNAi) analysis was then used to determine the developmental role of these genes. One RING finger gene, C32D5.10, showed a dramatic larval arrest upon RNAi. Three RING finger genes exhibited embryonic lethality after RNAi. These three genes include par-2, and two small RING finger proteins: F35G12.9 (an ortholog of APC11) and ZK287.5 (an ortholog of rbx1). Embryos from RNAi of the APC11 and rbx1 orthologs were arrested in the cell cycle, confirming the role of these particular RING finger proteins in regulation of the cell cycle. genesis 38:1-12, 2004.

Analysis of RING finger genes required for embryogenesis in C. elegans.

Die Analyse der RING-Finger-Gene f&#xFC;r Embryogenese in C. elegans erforderlich.

The anaphase-promoting complex or cyclosome (APC/C) is a multi-subunit ubiquitin ligase that regulates the eukaryotic cell cycle. APC/C belongs to the RING finger class of ubiquitin ligases that function by interacting with a ubiquitin-conjugating enzyme (Ubc), thus inciting the Ubc to transfer ubiquitin onto a target protein. Extensive studies with APC/C in other organisms have identified several possible Ubcs that might function as partners for APC/C. This report presents phenotypic and biochemical evidence showing that, in Caenorhabditis elegans, UBC-2 interacts specifically with the APC/C. This conclusion is based on three lines of evidence: first, the RNAi phenotype of ubc-2 is indistinguishable from RNAi phenotypes of APC/C subunits; second, RNAi of ubc-2 but not other Ubcs enhances the phenotype of hypomorphic APC/C mutants; third, purified UBC-2 and APC-11, the RING finger subunit of the APC/C, show robust ubiquitination activity in in vitro assays. APC-11 interaction is specific for UBC-2 as ubiquitination is not seen when APC-11 is combined other C. elegans Ubcs. As expected from the Ubc that functions with the APC/C, ubc-2(RNAi) produces metaphase blocks in both mitotic germ cells and in meiotic divisions of post-fertilization oocytes. In addition, ubc-2(RNAi) results in two germline phenotypes that appear to be unrelated to the APC/C: an expanded transition zone indicative of a pre-pachytene meiotic arrest and endo-reduplicated oocytes indicative of a problem in ovulation or oocyte-soma interactions.

Caenorhabditis elegans UBC-2 functions with the anaphase-promoting complex but also has other activities.

Caenorhabditis elegans UBC-2-Funktionen mit der Anaphase-Promoting Complex hat aber auch andere Aktivit&#xE4;ten.

Exo-pi-Bindung an eine ortho-Carboran hypercarbon Atom: systematische ikosaedrischen K&#xE4;fig Verzerrungen in den Strukturen der Fluor-, Hydroxy-und Amino-Carborane, 1-X-2-PH-1 ,2-C2B10H10 wider (X = F , OH oder NH 2) und verwandte Anionen.

The structures of derivatives of phenyl-ortho-carborane bearing on the second cage hypercarbon atom a pi-donor substituent (F, OH, O-, NH2, NH- and CH2-) were investigated by NMR, X-ray crystallography and computational studies. The molecular structures of these compounds, notably their cage C1-C2 distances and the orientations of their pi-donor substituents (OH, NH2, NH- and CH2-) show remarkable and systematic variations with the degree of exo pi-bonding, which varies as expected with the pi-donor characteristics of the substituent.

Exo-pi-bonding to an ortho-carborane hypercarbon atom: systematic icosahedral cage distortions reflected in the structures of the fluoro-, hydroxy- and amino-carboranes, 1-X-2-Ph-1,2-C2B10H10 (X=F, OH or NH2) and related anions.

The ubiquitin system is a well-conserved and pervasive process for post-synthetic modification of proteins. Three key components of the pathway are required for ubiquitination to occur: the E1 ubiquitin activating enzyme, the E2 ubiquitin conjugating enzyme, and the E3 ubiquitin ligase. There are several different E2 ubiquitin conjugating enzymes and an even greater number of E3 ubiquitin ligases. Interactions between these two groups are critical for substrate ubiquitination. This study reports a two-hybrid analysis of interactions within the ubiquitin system of Caenorhabditis elegans. Forty-three RING finger proteins (presumed E3 ubiquitin ligases) and 14 predicted E2 ubiquitin conjugating enzymes were included in the screen. A total of 31 E2-E3 interactions were uncovered. In addition, the UBC-13 conjugating enzyme was observed to interact with two different E2s, UEV-1 and UBC-1. The interaction of UBC-1 and UBC-13 was confirmed with in vitro ubiquitination reactions. Using NHL-1 as the E3 in the assays, ubiquitination was observed when both UBC-1 and UBC-13 were present but not with either alone. These data imply that some E2s require dimerization in order to function.

Interactions within the ubiquitin pathway of Caenorhabditis elegans.

Wechselwirkungen innerhalb des Ubiquitin-Weg von Caenorhabditis elegans.

Asymmetric localization of PAR proteins is a hallmark of polarized cells, but the mechanisms that create PAR asymmetry are not well understood. In the C. elegans zygote, PAR asymmetry is initiated by a transient actomyosin contraction, which sweeps the PAR-3/PAR-6/PKC-3 complex toward the anterior pole of the egg. The RING finger protein PAR-2 accumulates in a complementary pattern in the posterior cortex. Here we present evidence that PAR-2 participates in a feedback loop to stabilize polarity. PAR-2 is a target of the PKC-3 kinase and is excluded from the anterior cortex by PKC-3-dependent phosphorylation. The RING domain of PAR-2 is required to overcome inhibition by PKC-3 and stabilize PAR-2 on the posterior cortex. Cortical PAR-2 in turn prevents PAR-3/PAR-6/PKC-3 from returning to the posterior, in a PAR-1- and PAR-5-dependent manner. Our findings suggest that reciprocal inhibitory interactions among PAR proteins stabilize polarity by reinforcing an initial asymmetry in PKC-3.

Stabilization of cell polarity by the C. elegans RING protein PAR-2.

Asymmetrische Lokalisation der PAR-Proteine ist ein Markenzeichen der polarisierten Zellen, aber die Mechanismen, die PAR-Asymmetrie zu erstellen sind nicht gut verstanden. In der Zygote C. Elegans PAR Asymmetrie wird eingeleitet durch eine transiente Actomyosin Kontraktion, die fegt die PAR-3/PAR-6/PKC-3 Komplex in Richtung der vorderen Pol des Eies. Der Ringfinger-Protein sammelt PAR-2 in einem erg&auml;nzenden Muster im hinteren Kortex. Hier stellen wir Hinweise, dass eine Feedback-Schleife, Polarit&auml;t stabilisieren PAR-2 beteiligt. PAR-2 ist ein Ziel von der PKC-3-Kinase und ist von der anterioren Kortex von PKC-3-abh&auml;ngige Phosphorylierung ausgeschlossen. Die RING-Dom&auml;ne des PAR-2 wird ben&ouml;tigt, um zu &uuml;berwinden, Hemmung von PKC-3 und PAR-2 auf der hinteren Kortex zu stabilisieren. Kortikale PAR-2 verhindert wiederum, dass PAR-3/PAR-6/PKC-3 wieder auf die Posterior, PAR-1 und PAR-5-abh&auml;ngigen Weise. Unsere Ergebnisse weisen, dass wechselseitige hemmende Interaktionen zwischen PAR Proteine Polarit&auml;t stabilisieren durch Verst&auml;rkung einer anf&auml;nglichen Asymmetrie PKC-3.

Article	Year
Ubiquitin conjugating enzymes participate in polyglutamine protein aggregation. BMC cell biology\| PubMed ID: 17663792	2007
Postfertilization autophagy of sperm organelles prevents paternal mitochondrial DNA transmission. Science (New York, N.Y.)\| PubMed ID: 22033522	2011
Analysis of RING finger genes required for embryogenesis in C. elegans. Genesis (New York, N.Y. : 2000)\| PubMed ID: 14755799	2004
Caenorhabditis elegans UBC-2 functions with the anaphase-promoting complex but also has other activities. Journal of cell science\| PubMed ID: 15466891	2004
Exo-pi-bonding to an ortho-carborane hypercarbon atom: systematic icosahedral cage distortions reflected in the structures of the fluoro-, hydroxy- and amino-carboranes, 1-X-2-Ph-1,2-C2B10H1... Dalton transactions (Cambridge, England : 2003)\| PubMed ID: 15514767	2004
Interactions within the ubiquitin pathway of Caenorhabditis elegans. Biochemical and biophysical research communications\| PubMed ID: 15530417	2004
Stabilization of cell polarity by the C. elegans RING protein PAR-2. Developmental cell\| PubMed ID: 16459299	2006

Lynn Boyd

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