Deregulated expression of Cdc6 in the skin facilitates papilloma formation and affects the hair growth cycle.

Cdc6 encodes a key protein for DNA replication, responsible for the recruitment of the MCM helicase to replication origins during the G1 phase of the cell division cycle. The oncogenic potential of deregulated Cdc6 expression has been inferred from cellular studies, but no mouse models have been described to study its effects in mammalian tissues. Here we report the generation of K5-Cdc6, a transgenic mouse strain in which Cdc6 expression is deregulated in tissues with stratified epithelia.

A role for the DNA-damage checkpoint kinase Chk1 in the virulence program of the fungus Ustilago maydis.

During induction of the virulence program in the phytopathogenic fungus Ustilago maydis, the cell cycle is arrested on the plant surface and it is not resumed until the fungus enters the plant. The mechanism of this cell cycle arrest is unknown, but it is thought that it is necessary for the correct implementation of the virulence program. Here, we show that this arrest takes place in the G2 phase, as a result of an increase in the inhibitory phosphorylation of the catalytic subunit of the mitotic cyclin-dependent kinase Cdk1.

Pathocycles: Ustilago maydis as a model to study the relationships between cell cycle and virulence in pathogenic fungi.

Activation of virulence in pathogenic fungi often involves differentiation processes that need the reset of the cell cycle and induction of a new morphogenetic program. Therefore, the fungal capability to modify its cell cycle constitutes an important determinant in carrying out a successful infection. The dimorphic fungus Ustilago maydis is the causative agent of corn smut disease and has lately become a highly attractive model in addressing fundamental questions about development in pathogenic fungi.

The cdc25 phosphatase is essential for the G2/M phase transition in the basidiomycete yeast Ustilago maydis.

Cdc25-related phosphatases reverse the inhibitory phosphorylation of mitotic Cyclin-dependent kinases mediated by Wee1-related kinases, thereby promoting entry into mitosis. In the fission yeast, Schizosaccharomyces pombe, Cdc25 is required for entry into mitosis, while in the budding yeast Saccharomyces cerevisiae, Mih1 (the homologue of Cdc25) is not required for entry into mitosis or for viability. As these differences were linked to the different cell division and growth mechanism of these species, we sought to analyse the roles of Cdc25 in Ustilago maydis, which as S.

Inhibitory phosphorylation of a mitotic cyclin-dependent kinase regulates the morphogenesis, cell size and virulence of the smut fungus Ustilago maydis.

The regulation of cyclin-dependent kinase (CDK) activity through inhibitory phosphorylation seems to play an important role in the eukaryotic cell cycle. We have investigated the influence that inhibitory phosphorylation of the catalytic subunit of mitotic CDK has on cell growth and pathogenicity of the corn smut fungus Ustilago maydis. This model pathogen is worthy of attention since it is well suited to analyze the relationships between the cell cycle, morphogenesis and pathogenicity.