Endoreplication: The advantage to initiating DNA replication without the ORC?

Asano, Maki

doi:10.4161/fly.8087

Cited by 7 publications

(6 citation statements)

References 16 publications

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“…Another possibility is that Orc1 function in the salivary gland is provided by another of the Orc subunits. A discussion of possible Orc-independent endoreplication can be found in Asano (2009).…”

Section: Endocycle-specific Regulationmentioning

confidence: 99%

Endoreplication: polyploidy with purpose

Lee

Davidson²,

Duronio³

2009

Genes Dev.

521

507

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A great many cell types are necessary for the myriad capabilities of complex, multicellular organisms. One interesting aspect of this diversity of cell type is that many cells in diploid organisms are polyploid. This is called endopolyploidy and arises from cell cycles that are often characterized as “variant,” but in fact are widespread throughout nature. Endopolyploidy is essential for normal development and physiology in many different organisms. Here we review how both plants and animals use variations of the cell cycle, termed collectively as endoreplication, resulting in polyploid cells that support specific aspects of development. In addition, we discuss briefly how endoreplication occurs in response to certain physiological stresses, and how it may contribute to the development of cancer. Finally, we describe the molecular mechanisms that support the onset and progression of endoreplication.

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Section: Endocycle-specific Regulationmentioning

confidence: 99%

Endoreplication: polyploidy with purpose

Lee

Davidson²,

Duronio³

2009

Genes Dev.

521

507

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“…Moreover, in the endoreduplication program of leaf cells, the expression of both ORC3 and ORC4 is dispensable ( Barkla et al , 2018 ). Finally, based on the observation that cells of the salivary glands of Drosophila endoreduplicate without ORC1 ( Park and Asano, 2008 ), and that all subunits are required for the correct function of the ORC ( Chesnokov et al , 2001 ), Asano (2009) hypothesizes that the whole ORC complex might be dispensable for endoreduplication. Rather, the ORC would be replaced by another complex able to recruit CDC6, the Drosophila homolog of CDT1, and the MCM complex to assemble an alternative pre-RC complex exclusively devoted to the endoreduplication program.…”

Section: Discussionmentioning

confidence: 99%

ORIGIN OF RECOGNITION COMPLEX 3 controls the development of maternal excess endosperm in the Paspalum simplex agamic complex (Poaceae)

Bellucci

Cáceres

Paolocci

et al. 2023

Journal of Experimental Botany

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Pseudogamous apomixis in Paspalum simplex generates seeds with embryos genetically identical to the mother plant and endosperms deviating from the canonical 2(maternal):1(paternal) parental genome contribution into a maternal excess 4m:1p genome ratio. In P. simplex the gene homologous to the one coding for the subunit 3 of the ORIGIN OF RECOGNITION COMPLEX (PsORC3) exists in three isogenic forms: PsORC3a is apomixis-specific and constitutively expressed in developing endosperm whereas PsORCb and PsORCc are up regulated in sexual endosperms and silenced in apomictic ones. This raises the question of how the different arrangement and expression profiles of these three ORC3 isogenes are linked to seed development in interploidy crosses generating maternal excess endosperms. We demonstrate that the PsORC3b downregulation in sexual tetraploid plants is sufficient to restore seed fertility in interploidy 4n x 2n crosses and, in turn, its expression level at the transition from proliferating to endoreduplication endosperm developmental stages dictates the fate of these seeds. Furthermore, we show that only when being maternally inherited, PsORC3c can up-regulate PsORC3b. Our findings lay the basis for an innovative route - based on ORC3 manipulation - to introgress the apomictic trait into sexual crops and overcome the fertilization barriers in interploidy crosses.

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“…However, cell proliferation and gene amplification, assessed by loss of BrdU foci, were disrupted in these mutants. Asano (27) proposed the existence of a protein or complex X that can recruit Cdc6 and promote replication initiation. Such a factor, if it exists, also might play a role in late initiation at DAFC-34B.…”

Section: Discussionmentioning

confidence: 99%

Analysis of a Drosophila amplicon in follicle cells highlights the diversity of metazoan replication origins

Kim

Orr‐Weaver

2011

Proc. Natl. Acad. Sci. U.S.A.

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To investigate the properties of metazoan replication origins, recent studies in cell culture have adopted the strategy of identifying origins using genome-wide approaches and assessing correlations with such features as transcription and histone modifications. Drosophila amplicon in follicle cells (DAFCs), genomic regions that undergo repeated rounds of DNA replication to increase DNA copy number, serve as powerful in vivo model replicons. Because there are six DAFCs, compared with thousands of origins activated in the typical S phase, close molecular characterization of all DAFCs is possible. To determine the extent to which the six DAFCs are different or similar, we investigated the developmental and replication properties of the newly identified DAFC-34B. DAFC-34B contains two genes expressed in follicle cells, although the timing and spatial patterns of expression suggest that amplification is not a strategy to promote high expression at this locus. Like the previously characterized DAFC-62D, DAFC-34B displays origin activation at two separate stages of development. However, unlike DAFC-62D, amplification at the later stage is not transcription-dependent. We mapped the DAFC-34B amplification origin to 1 kb by nascent strand analysis and delineated cis requirements for origin activation, finding that a 6-kb region, but not the 1-kb origin alone, is sufficient for amplification. We analyzed the developmental localization of the origin recognition complex (ORC) and the minichromosome maintenance (MCM)2-7 complex, the replicative helicase. Intriguingly, the final round of origin activation at DAFC-34B occurs in the absence of detectable ORC, although MCMs are present, suggesting a new amplification initiation mechanism.gene amplification | oogenesis | chorion | developmental gene expression

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Endoreplication: The advantage to initiating DNA replication without the ORC?

Cited by 7 publications

References 16 publications

Endoreplication: polyploidy with purpose

Endoreplication: polyploidy with purpose

ORIGIN OF RECOGNITION COMPLEX 3 controls the development of maternal excess endosperm in the Paspalum simplex agamic complex (Poaceae)

Analysis of a Drosophila amplicon in follicle cells highlights the diversity of metazoan replication origins

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