Are there nucleic acids in the centrosome

This approximation was useful to know the centrosomal proteins interactions but it did not allow to explore the relationship between the centrosome and specific biological processes like the regulation of the cell cycle, the assembly of the mitotic spindle or its connection with other organelles or even diseases. This was our motivation for implementing a protein interactions tool in this new version of CentrosomeDB, where users can build an interactome network around this organelle and every other organelle and proteins categories that have been suspected of interacting with the centrosome.

Finally, although CentrosomeDB has compiled a large set of centrosomal genes from other databases, we have directed our efforts towards a different representation of the information, offering different perspectives to study the centrosome domains, orthology information and protein interactions.

Also, when researching a gene supported by other known sources, the user can be redirected to the original source. Looking at the increment in the number of centrosomal proteins with each new study, we believe that, although accurate, our insight of the proteomic constitution of the PCM is still very incomplete.

We can only assume that the advancing technologies will permit an increasing number of investigations on the centrosomal proteome and a consequent increase in the number of centrosomal proteins. With this in mind, our objective is to update CentrosomeDB on a regular basis, not only by our efforts, but also with the contribution of the scientific community, from whom we expect an active participation in compiling additional centrosomal genes, or modifying already existing information.

A submission form is available, being only necessary to present some sort of supportive evidence on the information to change or add. Google Scholar. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.

Sign In or Create an Account. Sign In. Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. CentrosomeDB: a new generation of the centrosomal proteins database for Human and Drosophila melanogaster.

Oxford Academic. Revision received:. Select Format Select format. Permissions Icon Permissions. Table 1. Number of genes with the strongest level of confidence Number of genes with a medium level of confidence 74 Number of genes with the lowest level of confidence 0 Number of genes supported by 1 evidence Number of genes supported by 2 evidences 30 Number of genes supported by 3 evidences 6.

Open in new tab. Figure 1. Open in new tab Download slide. Google Scholar Crossref. Search ADS. Proteomic characterization of the human centrosome by protein correlation profiling. A genome-wide RNAi screen to dissect centriole duplication and centrosome maturation in Drosophila. MiCroKit 3. New insights into subcomplex assembly and modifications of centrosomal proteins. Functional analysis of centrosomal kinase substrates in Drosophila melanogaster reveals a new function of the nuclear envelope component otefin in cell cycle progression.

ArrayExpress update—trends in database growth and links to data analysis tools. Centrosomal localization of cyclins E and A: structural similarities and functional differences.

Disconnecting the Golgi ribbon from the centrosome prevents directional cell migration and ciliogenesis. A Nupdependent NPC-anchored network tethers centrosomes to the nuclear envelope in prophase. Published by Oxford University Press. Issue Section:.

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They also point out that similarly localized non-coding RNAs are known to play a structural or catalytic role independent of translation. The first two reports described a set of RNAs that are significantly enriched in isolated centrosomes and includes confirmatory in situ hybridizations for four of these.

These four do not appear to be localized within the centrosome; rather, the centrosome appears to be localized within the RNA hybridization patch Fig. However, this is not conclusive because the resolution of light microscopic in situ hybridization may be deceiving, especially since the colored product of the phosphatase reaction can diffuse to some extent.

Also, localization of more than 20 other candidate transcripts has yet to be done. It is therefore unclear at this time whether any of these RNAs are preferentially associated with the centriole or pericentriolar matrix. Newly formed centrosomes embedded within a patch of RNA. As with the studies of Blower et al. Another unique quality of this set of RNAs is that they are exceedingly intron-poor, which stands in contrast to Tld , Eve , Dpp , Bub3 , cyclin B1 , and the others named above, all of which have an intron content comparable with the balance of their respective genomes.

Recently, a character that could shed some light on questions of centrosome content, biogenesis, and evolution has returned to the stage: the nucleolinus Alliegro et al. Still, the literature on the nucleolinus is scanty and we know little about it, other than to say it is an RNA-rich compartment closely associated with the nucleolus in a spectrum of cell types.

In some cells, such as Spisula oocytes, it is a distinct morphological entity. In other cells, it appears to be integrated within the nucleolus, and histological stains that are no longer in common use are required for its visualization Alliegro The nucleolinus is brought into this discussion because it was proposed to play a spindle-forming role in Spisula oocytes entering meiosis Allen ; and was long ago thought to be a direct precursor of centrosomes Lavdowsky Moreover, riboprobes to nucleolinar RNAs reveal an association with the centrosomes and spindle suggestive of a preexisting matrix, and experimental evidence supports the case for a role of the nucleolinus in forming the cell division apparatus Fig.

Induction of damage to the nucleolinus via laser microsurgery before centrosomes or a spindle form results in a dysmporhic meiotic spindle and failed chromatin segregation in parthenogenetically activated oocytes Alliegro et al.

Centrosomes can form, but their size and number appear to be disregulated. In oocytes fertilized with sperm after microsurgery, mitotic centrosomes and the spindle fail to form altogether. The precise role of the nucleolinus in these processes is not yet known, due in part to the complex origin of the microtuble organizing center during the first three division cycles in these zygotes. Spisula oocytes are arrested in prophase I of meiosis.

The first two meiotic divisions, which can be initiated by fertilization or parthenogenetic activation, are organized by maternally derived centrosomes. At the end of meiosis, the maternal centrosomes are suppressed and mitosis is governed by centrosomes derived, at least in part, from sperm Wu and Palazzo The mitotic centrosomes are replication-competent and carry the developing embryo through many rounds of cell division.

Regardless of the chain of events at the molecular level, it is clear that nucleolinar RNAs are closely associated with the centrosome and spindles during the early stages of meiosis and that this RNP is important for the formation of a normal, functioning cell division apparatus.

The nucleolinus may represent that domain of the nucleolus responsible for its cell cycle-related functions.

In some cell types, such as oocytes, the functional unit is gathered into a discrete morphological unit; in other cells, it is in a more integrated state. Centrosome formation in oocytes of the surf clam Spisula from the nucleolinar RNP. Unfertilized oocytes of Spisula solidissima are arrested in prophase of meiosis I. A large tetraploid nucleus, or germinal vesicle GV can be seen, with chromosomes blue attached to the nuclear envelope.

Within the GV is a prominent, nearly spherical nucleolus gray circle within the GV and nucleolinus red circle. Likewise, most centrosomal RNAs are not expressed before fertilization. However, some are present in the unactivated oocyte, in the nucleolinus. The GV and nucleolus dissipate during this time span. Shortly thereafter, the nucleolinus is no longer visible as a distinct structure, but its components can be visualized by in situ hybridization using probes to nucleolinar RNA red.

The centrosomes, chromosomes, and developing spindle come to lie in a matrix of RNA Alliegro et al. Alliegro and M. Alliegro, unpublished observations. Today, unless we choose to discount the technique of in situ RNA hybridization altogether, the evidence for specific RNAs associated with the spindle and centrosomes is overwhelming.

At least 15 distinct molecules for which the full length sequences are known have been localized to the centrosome by in situ hybridization in four laboratories Lambert and Nagy ; Alliegro et al. Others have been localized to the spindle Groisman et al. We may now return our attention to the function and origin of spindle and centrosomal RNAs. That RNAs of differentiation factors can be routed through centrosomes for delivery to select embryonic cells or that others can be directed to specific cytoplasmic domains for localized translation are, by now, unsurprising.

We have much to learn about these important processes. Yet, there are at least two other areas of inquiry regarding centrosome- and spindle-associated RNA with broader implications for cell biology: 1 the role of these nucleic acids in the assembly and organization of the microtubule-based cytoskeleton and 2 the origin and evolution of these RNAs and the structures with which they are associated.

These two questions regarding function and evolution, respectively, encompass key elements of the original paradigm that elicited so much interest.

Centriole replication has been described as generative, semiconservative, and independent of the nucleus. Based on these observations, it was posited that the duplication process could be templated by nucleic acid.

It followed that the presence of nucleic acids in the centriole or centrosome could signify an exogenous evolutionary origin, a model fueled by discoveries concerning mitochondria and chloroplasts. Recent experimental evidence Loncarek et al. However, nucleic acids do serve to scaffold macromolecular assemblages, as has been shown for RNA in the assembly and organization of the ribosome Woodson and the bacterial nucleoid Pettijohn and Hecht At the organellar level, the nucleus is ultimately scaffolded upon nucleic acids chromosomes at the conclusion of each telophase.

Examples such as these leave little doubt that nucleic acids do play a role in the assembly of the centrosome and spindle, though perhaps not by the mechanism of direct templating originally hypothesized. The second half of the paradigm, that these RNAs are remnants of an organellar genome, was mistakenly dismissed over our lack of definitive evidence for their existence from the s until recently.

Though this question remains unanswered, it should be the subject of reinvigorated inquiry as a result of recent findings. There is currently no evidence to directly support or refute this hypothesis, but there are some tantalizing observations in its favor. These include the intronless structure of at least some cnRNA genes Alliegro et al.

Findings of function, whether for trafficking or localized translation, have no bearing on the question, since identifying one function does not preclude another, much less an evolutionary history. Moreover, any organelle or molecular assemblage may be adopted for—so it may seem to us—unexpected or even disparate functions.

The hypothesis that centrosomal or spindle RNAs are descendants of an ancient endosymbiont remains as intriguing, provocative, and possible as ever. Meanwhile, our understanding of these structures as ribonucleoprotein complexes should broaden our grasp of their function and evolution as we uncover the rest of this story.

Ackerman GA Histochemistry of the centrioles and centrosomes of the leukemic cells from human myeloblastic leukemia.

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