Pattern Formation and Cell Differentiation: Trichomes in Arabidopsis as a Genetic Model System

Hülskamp, Martin; Schnittger, Arp; Folkers, Ulrike

doi:10.1016/s0074-7696(08)61053-0

Cited by 120 publications

(68 citation statements)

References 64 publications

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“…Moreover, similar behavior was found for fas1-1 leaves (En ecotype; data not shown). A rough correlation between trichome nuclear ploidy and branch number has also been observed (Hü lskamp et al, 1999;Castellano et al, 2004;Desvoyes et al, 2006). We observed that approximately 45% of fas1-4 trichomes developed more than four branches, in clear contrast to the wild-type situation, where approximately 3% of trichomes contain more than three branches (Supplemental Fig.…”

Section: Loss Of Caf-1 Inhibits Cell Divisionsupporting

confidence: 77%

E2F RegulatesFASCIATA1, a Chromatin Assembly Gene Whose Loss Switches on the Endocycle and Activates Gene Expression by Changing the Epigenetic Status

2007

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Maintenance of genome integrity depends on histone chaperone-mediated chromatin reorganization. DNA replicationassociated nucleosome deposition relies on chromatin assembly factor-1 (CAF-1). Depletion of CAF-1 in human cells leads to cell death, whereas in Arabidopsis (Arabidopsis thaliana), where it is involved in heterochromatin compaction and homologous recombination, plants are viable. The mechanism that makes the lack of CAF-1 activity compatible with development is not known. Here, we show that the FASCIATA1 (FAS1) gene, which encodes the CAF-1 large subunit, is a target of E2F transcription factors. Mutational studies demonstrate that one of the two E2F binding sites in its promoter has an activator role, whereas the other has a repressor function. Loss of FAS1 results in reduced type A cyclin-dependent kinase activity, inhibits mitotic progression, and promotes a precocious and systemic switch to the endocycle program. Selective up-regulation of the expression of a subset of genes, including those involved in activation of the G2 DNA damage checkpoint, also occurs upon FAS1 loss. This activation is not the result of a global change in chromatin structure, but depends on selective epigenetic changes in histone acetylation and methylation within a small region in their promoters. This suggests that correct chromatin assembly during the S-phase is required to prevent unscheduled changes in the epigenetic marks of target genes. Interestingly, activation of the endocycle switch as well as introduction of activating histone marks in the same set of G2 checkpoint genes are detected upon treatment of wild-type plants with DNA-damaging treatments. Our results are consistent with a model in which defects in chromatin assembly during the S-phase and DNA damage signaling share part of a pathway, which ultimately leads to mitotic arrest and triggers the endocycle program. Together, this might be a bypass mechanism that makes development compatible with cell division arrest induced by DNA damage stress.

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Section: Loss Of Caf-1 Inhibits Cell Divisionsupporting

confidence: 77%

E2F RegulatesFASCIATA1, a Chromatin Assembly Gene Whose Loss Switches on the Endocycle and Activates Gene Expression by Changing the Epigenetic Status

2007

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“…In addition, several Arabidopsis mutants that have altered trichomes support the correlation between cell size and nuclear size. Whereas wildtype trichomes have an DNA content of approximately 32C and develop mostly between three and four branches, mutants that have fewer endoreplication cycles have smaller trichomes with fewer branches [26]. Branch numbers and cell size are also increased in trichome mutants that have increased DNA contents [26].…”

Section: Cell Cycle and Cell Morphogenesismentioning

confidence: 99%

“…Whereas wildtype trichomes have an DNA content of approximately 32C and develop mostly between three and four branches, mutants that have fewer endoreplication cycles have smaller trichomes with fewer branches [26]. Branch numbers and cell size are also increased in trichome mutants that have increased DNA contents [26]. Misexpression of a CDK inhibitor, and thus presumed direct interference with cell-cycle progression, concurrently reduced DNA levels and the size and branch number of trichomes.…”

Section: Cell Cycle and Cell Morphogenesismentioning

confidence: 99%

Cell cycle and differentiation

Jakoby

Schnittger

2004

Current Opinion in Plant Biology

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“…Trichomes usually undergo four to five rounds of endoreplication leading to a final DNA content between 32C and 64C (23,24). The putative CDK inhibitor SIAMESE (SIM) is crucial for the endoreplication program (25,26).…”

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confidence: 99%

CULLIN 4-RING FINGER-LIGASE plays a key role in the control of endoreplication cycles in Arabidopsis trichomes

Roodbarkelari

Bramsiepe

Weinl

et al. 2010

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

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One of the predominant cell-cycle programs found in mature tissues is endoreplication, also known as endoreduplication, that leads to cellular polyploidy. A key question for the understanding of endoreplication cycles is how oscillating levels of cyclindependent kinase activity are generated that control repeated rounds of DNA replication. The APC/C performs a pivotal function in the mitotic cell cycle by promoting anaphase and paving the road for a new round of DNA replication. However, using marker lines and plants in which APC/C components are knocked down, we show here that outgrowing and endoreplicating Arabidopsis leaf hairs display no or very little APC/C activity. Instead we find that RBX1-containing Cullin-RING E3 ubiquitin-Ligases (CRLs) are of central importance for the progression through endoreplication cycles; in particular, we have identified CULLIN4 as a major regulator of endoreplication in Arabidopsis trichomes. We have incorporated our findings into a bio-mathematical simulation presenting a robust two-step model of endoreplication control with one type of cyclindependent kinase inhibitor function for entry and a CRL-dependent oscillation of cyclin-dependent kinase activity via degradation of a second type of CDK inhibitor during endoreplication cycles.cell cycle | endoreduplication | CDK inhibitor | cell differentiation | protein degradation

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Pattern Formation and Cell Differentiation: Trichomes in Arabidopsis as a Genetic Model System

Cited by 120 publications

References 64 publications

E2F RegulatesFASCIATA1, a Chromatin Assembly Gene Whose Loss Switches on the Endocycle and Activates Gene Expression by Changing the Epigenetic Status

E2F RegulatesFASCIATA1, a Chromatin Assembly Gene Whose Loss Switches on the Endocycle and Activates Gene Expression by Changing the Epigenetic Status

Cell cycle and differentiation

CULLIN 4-RING FINGER-LIGASE plays a key role in the control of endoreplication cycles in Arabidopsis trichomes

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