Christian J Malone et al. (2005) International Worm Meeting "Centrosomal attachment to the nucleus."

Yi Chen, Cheryl Keller, Zhizhen Gao, Christian J Malone, Il Minn

[International Worm Meeting, 2005]

The centrosome and nucleus are intimately associated during interphase in a variety of organisms and cell types, yet the importance and mechanism of the attachment are just beginning to be understood. Mutations in the C. elegans gene zyg-12 specifically perturb the attachment of the centrosome to the nucleus during early embryogenesis. zyg-12 encodes multiple isoforms of Hook-like proteins. Hook proteins mediate the interaction of membrane-bound organelles such as the Golgi with the microtubule cytoskeleton. ZYG-12 isoforms localize to both nuclear envelope and centrosomes if they include a transmembrane domain or just centrosomes if they do not. ZYG-12 localization to the centrosomes, but not the nuclear envelope, requires microtubules. Conversely, ZYG-12 localization to the nuclear envelope, but not the centrosome, requires sun-1, a second gene required for centrosomal attachment. SUN-1 localizes to the nuclear envelope and includes a conserved SUN domain. We are working to characterize both the mechanism of attachment and how ZYG-12 localizes to the nuclear envelope via a SUN-1 dependent mechanism.

Christian J Malone et al. (2001) International C. elegans Meeting "zyg-12 is required for the positioning of C elegans centrosomes"

Christian J Malone, John G White

[International C. elegans Meeting, 2001]

Although the centrosome is associated with the nuclear envelope during interphase in a variety of organisms and cell types, the mechanism of this association is largely unknown. The only protein known to be involved in this process, dynein, has been shown to play only a minor role in the interaction in both C. elegans and Drosophila . We report that a temperature sensitive (ts) maternal effect mutation, zyg-12(ct350), caused completely penetrant dissociation of the centrosome and the nucleus. Embryos at the 1-cell stage from homozygous mutant mothers appeared normal except for the dissociated centrosomes. To address whether zyg-12(ct350) is disrupting centrosomal positioning through a disruption of dynein activity, we looked for other dynein dependent activities. Centrosome separation, centrsosome movement away from the cortex and dynein-mediated transport are normal in zyg-12(ct350) embryos, suggesting that dynein function is also normal. Time-lapse optical sectioning of zyg-12(ct350) embryos revealed, except for dissociated centrosomes, otherwise normal embryonic development. For example, mitosis and establishment of polarity both appeared normal. This suggests that centrosomes may be able to function normally in the absence of nuclear association. To address whether centrosome function was otherwise normal, I assayed their ability to organize microtubules. I created an integrated ßtubulin::GFP transgene using micro-particle bombardment 1 . Analysis of zyg-12(ct350) in the ßtubulin::GFP background indicated that centrosomes appeared completely wild-type in their ability to organize both astral and spindle microtubules. Therefore, zyg-12 may be specifically required for the association of the centrosome and the nucleus and may help elucidate the molecular mechanism of this association. 1 Praitis et al. 2001. Genetics. 157: 1217.

Christian J Malone et al. (2003) International Worm Meeting "The C. elegans hook protein, ZYG-12, mediates the essential attachment between the centrosome and nucleus"

Julie Ahringer, Lisa Misner, Nathalie Le Bot, Christian J Malone, John G White

[International Worm Meeting, 2003]

The centrosome and nucleus are intimately associated during interphase in a variety of organisms and cell types, yet the role of the attachment in cell division and development, as well as the molecular mechanism of the attachment, are largely unknown. Loss of dynein function causes a low frequency of centrosomal attachment defects in both C. elegans and Drosophila. Mutations in the C. elegans gene zyg-12 perturb the attachment of the centrosome to the nucleus during early embryogenesis in all embryos observed. Analysis of the mutant phenotypes demonstrates for the first time that this attachment is essential for normal spindle morphology, pronuclear migration and nuclear anchoring. Loss of the attachment leads to mitotic defects and genomic instability. Molecular characterization of zyg-12 reveals that it encodes multiple isoforms of Hook-like proteins. Hook proteins mediate the interaction of membrane-bound organelles such as the Golgi with the microtubule cytoskeleton. We observe that functional GFP::ZYG-12 isoforms localize to both nuclear envelope and centrosomes if they include a transmembrane domain or just centrosomes if they do not. Disruption of microtubules by depletion of alpha-tubulin demonstrates that the localization of ZYG-12 to the centrosomes, but not the nuclear envelope, requires microtubules. We have recently identified a second gene, with phenotypes similar to zyg-12, that is required for ZYG-12 localization to the nuclear envelope but not the centrosome. A two-hybrid screen using ZYG-12 as bait identified an interaction with the DLI-1 subunit of dynein. ZYG-12 is required for dynein localization to the nuclear envelope but not other structures, while ZYG-12 localizes to the nuclear envelope independently of dynein. We propose a two-step model of centrosome attachment to the nucleus. Initially, dynein, which localizes to the nuclear envelope via its interaction with ZYG-12, moves the centrosome towards the nucleus. After proximity is established, ZYG-12 isoforms at both the nucleus and centrosome, but not dynein, are required for the anchorage of the centrosome.

Hannak E et al. (2002) J Cell Biol "The kinetically dominant assembly pathway for centrosomal asters in Caenorhabditis elegans is gamma-tubulin dependent."

Habermann B, Hannak E, Kirkham M, Gonczy P, Oegema K, Hyman AA

[J Cell Biol, 2002]

gamma-Tubulin-containing complexes are thought to nucleate and anchor centrosomal microtubules (MTs). Surprisingly, a recent study (Strome, S., J. Powers, M. Dunn, K. Reese, C.J. Malone, J. White, G. Seydoux, and W. Saxton. Mol. Biol. Cell. 12:1751-1764) showed that centrosomal asters form in Caenorhabditis elegans embryos depleted of gamma-tubulin by RNA-mediated interference (RNAi). Here, we investigate the nucleation and organization of centrosomal MT asters in C. elegans embryos severely compromised for gamma-tubulin function. We characterize embryos depleted of approximately 98% centrosomal gamma-tubulin by RNAi, embryos expressing a mutant form of gamma-tubulin, and embryos depleted of a gamma-tubulin-associated protein, CeGrip-1. In all cases, centrosomal asters fail to form during interphase but assemble as embryos enter mitosis. The formation of these mitotic asters does not require ZYG-9, a centrosomal MT-associated protein, or cytoplasmic dynein, a minus end-directed motor that contributes to self-organization of mitotic asters in other organisms. By kinetically monitoring MT regrowth from cold-treated mitotic centrosomes in vivo, we show that centrosomal nucleating activity is severely compromised by gamma-tubulin depletion. Thus, although unknown mechanisms can support partial assembly of mitotic centrosomal asters, gamma-tubulin is the kinetically dominant centrosomal MT nucleator.

McGhee JD (1987) Biochemistry "Purification and characterization of a carboxylesterase from the intestine of the nematode Caenorhabditis elegans."

McGhee JD

[Biochemistry, 1987]

The major intestinal esterase from the nematode Caenorhabditis elegans has been purified to essential homogeneity. Starting from whole worms, the overall purification is 9000-fold with a 10% recovery of activity. The esterase is a single polypeptide chain of Mr 60,000 and is stoichiometrically inhibited by organophosphates. Substrate preferences and inhibition patterns classify the enzyme as a carboxylesterase (EC 3.1.1.1), but the physiological function is unknown. The sequence of 13 amino acid residues at the esterase N- terminus has been determined. This partial sequence shows a surprisingly high degree of similarity to the N-terminal sequence of two carboxylesterases recently isolated from Drosophila mojavensis [Pen, J., van Beeumen, J., & Beintema, J. J. (1986) Biochem. J. 238, 691-699].

Murakami S et al. (1996) West Coast Worm Meeting "ARE AGE-1 AND DAF-23 ALLELIC?"

Murakami S, Johnson TE, Duhon SA, Kliminskaya M

[West Coast Worm Meeting, 1996]

Recently, Malone et al (1996) found that age-1 strains (hx542 and hx546) show a Daf-c phenotype at semi-lethal 27 oC. They also showed that age-1(hx546) fails to complement daf-23 alleles. We found that the age-1(hx546) strains contain two Daf-c mutations close to each other. One Daf-c is mapped between sqt-1 and lin-29, where daf-23 is located; the other is to the left of sqt-1, perhaps consistent with the original map position of age-1. These results are not necessarily contradictory to Malone et al, since they used recombinants from mapping Daf-c in the age-1 strains. We are testing whether either Daf-c is responsible for failure to complement daf-23 and/or for failure to complement new alleles of age-1. Current data will be presented.

Murakami S et al. (1999) Curr Biol "Life extension and stress resistance in Caenorhabditis elegans modulated by the tkr-1 gene."

Johnson TE, Murakami S

[Curr Biol, 1999]

In this Brief Communication, which appeared in the 14 September 1998 issue of Current Biology, the UV dose was reported erroneously. The dose reported was 20 J/m2 but the actual dose used was 0.4 J/cm2. Also, the gene formally referred to as tkr-1 has since been renamed old-1 (overexpression longevity determination).

Ramos CG et al. (2014) J Bacteriol "Retraction for Ramos et al., MtvR is a global small noncoding regulatory RNA in Burkholderia cenocepacia."

Feliciano JR, da Costa PJ, Ramos CG, Grilo AM, Leitao JH

[J Bacteriol, 2014]

Volume 195, no. 16, p. 35143523, 2013. A number of problems related to images published in this paper have been brought to our attention. Figure 1D contains duplicated images in lanes S and LE, and Fig. 4D and 6B contain images previously published in articles in this journal and in Microbiology and Microbial Pathogenesis, i.e., the following: C. G. Ramos, S. A. Sousa, A. M. Grilo, J. R. Feliciano, and J. H. Leitao, J. Bacteriol. 193:15151526, 2011. doi:10.1128/JB.01374-11. S. A. Sousa, C. G. Ramos, L. M. Moreira, and J. H. Leitao, Microbiology 156:896908, 2010. doi:10.1099/mic.0.035139-0. C. G. Ramos, S. A. Sousa, A. M. Grilo, L. Eberl, and J. H. Leitao, Microb. Pathog. 48:168177, 2010. doi: 10.1016/j.micpath.2010.02.006. Therefore, we retract the paper. We deeply regret this situation and apologize for any inconvenience to the editors and readers of Journal of Bacteriology, Microbial Pathogenesis, and Microbiology.

Nillegoda NB et al. (2015) Nature "Crucial HSP70 co-chaperone complex unlocks metazoan protein disaggregation."

Berynskyy M, Morimoto RI, Bukau B, Stengel F, Kirstein J, Szlachcic A, Arnsburg K, Stank A, Scior A, Nillegoda NB, Gao X, Guilbride DL, Aebersold R, Wade RC, Mayer MP

[Nature, 2015]

Protein aggregates are the hallmark of stressed and ageing cells, and characterize several pathophysiological states. Healthy metazoan cells effectively eliminate intracellular protein aggregates, indicating that efficient disaggregation and/or degradation mechanisms exist. However, metazoans lack the key heat-shock protein disaggregase HSP100 of non-metazoan HSP70-dependent protein disaggregation systems, and the human HSP70 system alone, even with the crucial HSP110 nucleotide exchange factor, has poor disaggregation activity in vitro. This unresolved conundrum is central to protein quality control biology. Here we show that synergic cooperation between complexed J-protein co-chaperones of classes A and B unleashes highly efficient protein disaggregation activity in human and nematode HSP70 systems. Metazoan mixed-class J-protein complexes are transient, involve complementary charged regions conserved in the J-domains and carboxy-terminal domains of each J-protein class, and are flexible with respect to subunit composition. Complex formation allows J-proteins to initiate transient higher order chaperone structures involving HSP70 and interacting nucleotide exchange factors. A network of cooperative class A and B J-protein interactions therefore provides the metazoan HSP70 machinery with powerful, flexible, and finely regulatable disaggregase activity and a further level of regulation crucial for cellular protein quality control.

Miller DM et al. (1992) Worm Breeder's Gazette "unc-4 LacZ Expression in A-Type Motor Neurons"

Miller DM, Niemeyer CJ

[Worm Breeder's Gazette, 1992]

unc-4 LacZ expression in A-type motor neurons David M. Miller and Charles J. Niemeyer, Dept. of Cell Biology, Duke Univ. Medical Ctr, Durham, NC 27710