Tribbles, a cell-cycle brake that coordinates proliferation and morphogenesis during Drosophila gastrulation.
BACKGROUND
The final shape and size of an organism is determined by both morphogenetic processes and cell proliferation and it is essential that these processes be properly coordinated. In particular, cell division is incompatible with certain types of morphogenetic cell behaviour, such as migration, adhesion and changes in cell shape. Mechanisms must therefore exist to ensure that one does not interfere with the other.


RESULTS
We address here the coordination of proliferation and morphogenesis during the development of the mesoderm in Drosophila. We show that it is essential that mitosis be blocked in the mesoderm during early gastrulation, and identify the putative serine/threonine kinase Tribbles as controlling this block. In its absence, the mitotic block is lifted, resulting in severe defects during early gastrulation. Tribbles, a homologue of a group of vertebrate proteins of unknown function, acts in concert with another, as yet unidentified, factor to counteract the activity of the protein phosphatase Cdc25/String.


CONCLUSIONS
In a finely tuned balance with Cdc25/String, Tribbles controls the timing of mitosis in the prospective mesoderm, allowing cell-shape changes to be completed. This mechanism for coordinating cell division and cell-shape changes may have helped Drosophila to evolve its mode of rapid early development.
Seher
T C
TC
Institute of Genetics, University of Cologne, Germany.
Leptin
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D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002455:Cell Division; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology*; D005775:Gastrula / Q000166:cytology* / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008648:Mesoderm / Q000166:cytology / Q000502:physiology; D008938:Mitosis; D008969:Molecular Sequence Data; D009024:Morphogenesis; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017027:Protein Tyrosine Phosphatases; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; C410505:trbl protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D010749:Phosphoprotein Phosphatases; D017027:Protein Tyrosine Phosphatases; C059217:stg protein, Drosophila