Project description:This SuperSeries is composed of the following subset Series: GSE29800: Lack of G1 cyclin arrest cell cycle synchronization time-course microarray in Glucose GSE29892: Alpha Factor arrest cell cycle synchronization time-course microarray in Galactose GSE29893: Alpha Factor arrest cell cycle synchronization time-course microarray in Glucose Refer to individual Series
Project description:The large majority of oxidative lesions occurring in the G1 phase of the cell cycle are repaired by base excision repair (BER) rather than mismatch repair (MMR) to avoid long resections that can lead to genomic instability and cell death. However, how cells choose BER over MMR is not yet understood. Here, we show that, during G1, D-type cyclins are recruited to sites of oxidative DNA damage in a PCNA- and p21-dependent manner. In turn, in a manner that is independent on CDK4/6 activity, D-type cyclins stabilize p21, which competes through its PCNA-interacting protein (PIP) box with MMR components for their binding to PCNA. This reduces MMR activity while allowing BER. At the G1/S transition, the AMBRA1-dependent degradation of D-type cyclins renders p21 susceptible to proteolysis via SKP2 and CDT2. These timely degradation events allow the proper binding of MMR proteins to PCNA enabling the repair of DNA replication errors. Thus, the expression of D-type cyclins limit MMR in G1, whereas their degradation is necessary for proper MMR function in S. Defects in these two regulatory mechanisms promote genome instability. The mass spectrometry raw files correspond to the affinity purifications of proximity labeled (turbo-ID) PCNA and CCND1 under various conditions.
Project description:Two models have been put forward for cyclin-dependent kinase (Cdk) control of the cell cycle. In the qualitative model, cell cycle events are ordered by distinct substrate specificities associated with successive waves of G1, S and mitotic cyclins. Alternatively, the gradual quantitative rise of Cdk activity from G1 phase to mitosis could lead to ordered substrate phosphorylation at sequential thresholds. Here, we study the relative contributions of qualitative and quantitative Cdk control in the budding yeast S. cerevisiae. S-phase cyclins can be replaced by a single mitotic cyclin, albeit at the cost of reduced fitness. The single cyclin can in addition replace G1 cyclins to support ordered cell cycle progression, fulfilling key predictions of the quantitative model. However, single-cyclin cells fail to polarize or grow buds and thus cannot sustain proliferation. Our results suggest that budding yeast has become dependent on G1 cyclin specificity to couple cell cycle progression to essential morphogenetic events.
Project description:A long-term goal in cancer research has been to inhibit the cell cycle in tumour cells without causing toxicity in proliferative healthy tissues. The best evidence that this is achievable is provided by CDK4/6 inhibitors, which arrest the cell cycle in G1, are well-tolerated in patients, and are effective in treating ER+/HER2- breast cancer. CDK4/6 inhibitors are effective because they arrest tumour cells more efficiently than some healthy cell types and, in addition, they affect the tumour microenvironment to enhance anti-tumour immunity. We demonstrate here another reason to explain their efficacy. Tumour cells are specifically vulnerable to CDK4/6 inhibition because during the G1 arrest, oncogenic signals drive toxic cell overgrowth. This overgrowth causes permanent cell cycle withdrawal by either preventing progression from G1 or by inducing replication stress and genotoxic damage during the subsequent S-phase and mitosis. Inhibiting or reverting oncogenic signals that converge onto mTOR can rescue this excessive growth, DNA damage and cell cycle exit in cancer cells. Conversely, inducing oncogenic signals in non-transformed cells can drive these toxic phenotypes and sensitize cells to CDK4/6 inhibition. Together, this demonstrates how oncogenic signals that have evolved to stimulate constitutive tumour growth and proliferation driven subverted to cause toxic cell growth and irreversible cell cycle exit when proliferation is halted in G1.
Project description:Endothelial cells derived from hESCs were separated into 4 different cell cycle phases via FACS and sequenced (i.e., early G1, late G1, G1/S, S/G2/M)
Project description:This experiment measured the mono-methylation of lysine 37 of histone H3 in yeast cells at various phases of the cell cycle (G1, G1/S and S).
Project description:We report that ancestral zinc-finger-domain transcriptional regulators, previously reported to control virulence/symbiosis, implement a cell cycle (S→G1) transcriptional switch. To unravel how this G1-phase transcriptional program is reinstated during a primitive cell cycle, we first defined G1-specific promoters in the model bacterium Caulobacter crescentus by comparative ChIP-Seq analysis. We then exploited one such promoter as genetic proxy, to identify two conserved developmental regulator paralogs, MucR1/2, that constitute a quadripartite and homeostatic regulatory module directing the switch from S→G1-phase transcription. Surprisingly, MucR orthologs that regulate virulence and symbiosis gene transcription in Brucella, Agrobacterium or Sinorhizobium support the G1 transcriptional switch in Caulobacter. Pan-genomic ChIP-Seq analyses in Sinorhizobium and Caulobacter show that this module targets orthologous genes. Thus, this ancestral bacterial lineage from which eukaryotic organelles descended may coordinate virulence/symbiosis with other cell cycle functions using a primordial transcription factor fold that is now primarily found in the eukaryotic domain of life.
Project description:We report that ancestral zinc-finger-domain transcriptional regulators, previously reported to control virulence/symbiosis, implement a cell cycle (SM-bM-^FM-^RG1) transcriptional switch. To unravel how this G1-phase transcriptional program is reinstated during a primitive cell cycle, we first defined G1-specific promoters in the model bacterium Caulobacter crescentus by comparative ChIP-Seq analysis. We then exploited one such promoter as genetic proxy, to identify two conserved developmental regulator paralogs, MucR1/2, that constitute a quadripartite and homeostatic regulatory module directing the switch from SM-bM-^FM-^RG1-phase transcription. Surprisingly, MucR orthologs that regulate virulence and symbiosis gene transcription in Brucella, Agrobacterium or Sinorhizobium support the G1 transcriptional switch in Caulobacter. Pan-genomic ChIP-Seq analyses in Sinorhizobium and Caulobacter show that this module targets orthologous genes. Thus, this ancestral bacterial lineage from which eukaryotic organelles descended may coordinate virulence/symbiosis with other cell cycle functions using a primordial transcription factor fold that is now primarily found in the eukaryotic domain of life. Examination of 5 transcripton factor binding in two different species