Directing Cell Division During Development

O’Farrell, Patrick H.; Edgar, Bruce A.; Lakich, Delia; Lehner, Christian F.

doi:10.1126/science.2683080

Cited by 176 publications

(76 citation statements)

References 53 publications

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“…In this context, Drosophila embryos appear to have an essentially unregulated basic cell cycle oscillator during cycles 1-13. These cycles consist of a rapid progression of M and S phases, and are driven by maternally supplied products using exclusively posttranscriptional mechanisms O'Farrell et al, 1989). Following mitosis 13, this basic cycle is modified by the addition of G2 phases of variable length.…”

Section: Modes Of Embryonic Cell Cycle Regulationmentioning

confidence: 99%

“…This suggests that much of the complexity in division patterns is not absolutely required. One plausible explanation for "empty" complexity in the division pattern stems from our hypothesis that stg transcription is regulated by a battery of segmentation and homeotic ("selector") genes O'Farrell et al, 1989). These genes encode spatially regulated transcription factors that determine, in addition to cell cycle patterns (Foe and Odell, 1989), virtually all other aspects of cell fate.…”

Section: Cell Division and Developmentmentioning

confidence: 99%

“…In yeast, removing cdc25 + function causes a first cycle arrest in the G2 phase. In Drosophila, removing zygotic stg function causes G2 arrest in interphase 14, just prior to the first mitosis that requires zygotic transcription Edgar and O'Farrell, 1989;O'Farrell et al, 1989). This arrest point is correlated with the abrupt degradation of maternal stg mRNA in early interphase 14.…”

Section: Introductionmentioning

confidence: 99%

“…Although the regulation of stg has not yet been studied in detail, several observations suggest that stg expression is controlled at the transcriptional level by combinations of segmentation and homeotic gene products O'Farrell et al, 1989; A. E., unpublished data). A second major question concerns the generality of stg as a cell cycle regulator during development.…”

Section: Introductionmentioning

confidence: 99%

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The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2 by string

Edgar

O’Farrell

1990

Cell

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SummaryThe string (stg) locus of Drosophila encodes a factor that is thought to trigger mitosis by activating the p34 cdc2 protein kinase. stg is required for mitosis early in development and is transcribed in a dynamic pattern that anticipates the pattern of embryonic cell divisions. Here we show that differential cell cycle regulation during postblastoderm development (cell cycles 14-16) occurs in G2. We demonstrate that stg mRNA expressed from a heat shock promotor triggers mitosis, and an associated S phase, in G2 cells during these cycles. Hence, differential cell cycle timing at this developmental stage is controlled by stg. Finally, we use heat-induced stg expression to alter the normal pattern of embryonic mitoses. Surprisingly, the complex mitotic pattern evident during normal development is not essential for many features of pattern formation or for viability.

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Section: Modes Of Embryonic Cell Cycle Regulationmentioning

confidence: 99%

Section: Cell Division and Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2 by string

Edgar

O’Farrell

1990

Cell

Self Cite

420

326

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“…In theory, these studies could also be performed using the mutational inhibition of dynein and KLP61F. However, because severe loss-of-function mutations in the genes encoding these motors are lethal, and because maternal transcripts and proteins are loaded into early embryos (O'Farrell et al, 1989), we thought that this approach would not be appropriate for our purposes. Therefore, only Ncd, which is not essential for the survival of embryos or the formation of spindles, was inhibited genetically.…”

Section: Experimental Rationalementioning

confidence: 99%

Functional Coordination of Three Mitotic Motors inDrosophilaEmbryos

Sharp

Brown

Kwon

et al. 2000

MBoC

218

293

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It is well established that multiple microtubule-based motors contribute to the formation and function of the mitotic spindle, but how the activities of these motors interrelate remains unclear.Here we visualize spindle formation in living Drosophila embryos to show that spindle pole movements are directed by a temporally coordinated balance of forces generated by three mitotic motors, cytoplasmic dynein, KLP61F, and Ncd. Specifically, our findings suggest that dynein acts to move the poles apart throughout mitosis and that this activity is augmented by KLP61F after the fenestration of the nuclear envelope, a process analogous to nuclear envelope breakdown, which occurs at the onset of prometaphase. Conversely, we find that Ncd generates forces that pull the poles together between interphase and metaphase, antagonizing the activity of both dynein and KLP61F and serving as a brake for spindle assembly. During anaphase, however, Ncd appears to have no effect on spindle pole movements, suggesting that its activity is downregulated at this time, allowing dynein and KLP61F to drive spindle elongation during anaphase B. INTRODUCTIONThe segregation of chromosomes during mitosis depends on the action of a self-organizing, bipolar machine called the mitotic spindle. It is now established that the formation and function of the mitotic spindle requires numerous microtubule (MT)-based motor proteins (Hoyt and Geiser, 1996;Vale and Fletterick, 1997). Although the identities of many of these mitotic motors are becoming clear, their specific functional interrelationships have been extremely difficult to ascertain.Among all mitotic movements, the positioning of spindle poles during the assembly and elongation of the bipolar mitotic spindle may require the greatest degree of cooperation between different motors. This process is particularly complex because it occurs in a pathway consisting of several, temporally distinct stages, during which the organization of spindle microtubules and the general environment of the cell change dramatically (McIntosh and McDonald, 1989). The members of at least three families of MT motors are thought to play important roles in this pathway. These are the bipolar kinesins, the C-terminal kinesins, and cytoplasmic dynein.The bipolar (or BimC) kinesins (Vale and Fletterick, 1997) comprise a family of plus-end-directed motors, which have a bipolar morphology with motor domains at both ends of a central rod (Cole et al., 1994; Kashina et al., 1996a,b; Gordon and Roof, 2000). Functionally, these motors are thought to play a role in either the assembly or maintenance of spindle bipolarity, because their inhibition results in the formation of monopolar mitotic spindles (Enos and Morris, 1990;Hagan and Yanagida, 1990;Roof et al., 1991;Hoyt et al., 1992;Sawin et al., 1992;Heck et al., 1993;Blangy et al., 1995;Sharp et al., 1999b). Support for a role for bipolar kinesins in spindle maintenance but not assembly comes from the recent findings that inhibiting the Drosophila bipolar kinesin KLP61F does not pr...

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Reduction in cell size during development of the spinal cord

1999

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During development, spinal cord cells of the frog Xenopus laevis undergo a reduction in size. This phenomenon occurs during neural tube formation and continues at least until the start of metamorphosis. The number and shape of spinal cord cells also changes, but not always in synchrony with the reduction in cell size. The concomitant change in size and number of spinal cord cells during embryogenesis suggests that a cleavage type of reductive division contributes to the decrease in cell size. Blocking cell division with a combination of hydroxyurea and aphidicolin (HUA) stops the decrease in cell size during embryonic development without affecting the differentiation of a specific class of catecholaminergic neurons. HUA treatment during larval stages does not block the decrease in catecholaminergic neuron size. Thus, both mitotic and postmitotic cells decrease in size during spinal cord development. The two mechanisms are prevalent at different developmental stages with reductive division and cellular atrophy common during embryonic and larval phases, respectively. Like other regressive changes such as cell death and synapse elimination, decreases in cell size affect spinal cord morphogenesis and presumably the function of developing spinal cord cells. J. Comp. Neurol. 409:592–602, 1999. © 1999 Wiley‐Liss, Inc.

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Directing Cell Division During Development

Cited by 176 publications

References 53 publications

The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2 by string

The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2 by string

Functional Coordination of Three Mitotic Motors inDrosophilaEmbryos

Reduction in cell size during development of the spinal cord

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