Opposing roles for DNA replication initiator proteins ORC1 and CDC6 in control of Cyclin E gene transcription

Hossain, Manzar; Stillman, Bruce

doi:10.7554/elife.12785

Cited by 30 publications

(42 citation statements)

References 69 publications

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“…Full-length SAMHD1 and its deleted derivatives were fused to Glutathione S transferase (GST) by cloning into the bacterial expression vector PGEX6P1 (GE Healthcare Life Sciences). The GST fusion proteins were expressed and purified using Glutathione sepharose beads according to the procedure described previously[47]. …”

Section: Methodsmentioning

confidence: 99%

The dNTP triphosphohydrolase activity of SAMHD1 persists during S-phase when the enzyme is phosphorylated at T592

et al. 2018

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SAMHD1 is the major catabolic enzyme regulating the intracellular concentrations of DNA precursors (dNTPs). The S-phase kinase CDK2-cyclinA phosphorylates SAMHD1 at Thr-592. How this modification affects SAMHD1 function is highly debated. We investigated the role of endogenous SAMHD1 phosphorylation during the cell cycle. Thr-592 phosphorylation occurs first at the G1/S border and is removed during mitotic exit parallel with Thr-phosphorylations of most CDK1 targets. Differential sensitivity to the phosphatase inhibitor okadaic acid suggested different involvement of the PP1 and PP2 families dependent upon the time of the cell cycle. SAMHD1 turn-over indicates that Thr-592 phosphorylation does not cause rapid protein degradation. Furthermore, SAMHD1 influenced the size of the four dNTP pools independently of its phosphorylation. Our findings reveal that SAMHD1 is active during the entire cell cycle and performs an important regulatory role during S-phase by contributing with ribonucleotide reductase to maintain dNTP pool balance for proper DNA replication.

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Section: Methodsmentioning

confidence: 99%

The dNTP triphosphohydrolase activity of SAMHD1 persists during S-phase when the enzyme is phosphorylated at T592

et al. 2018

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“…Human ORC binds DNA in an apparent sequence-independent manner and with CDC6 and CDT1 can assembly MCM2-7 onto DNA in vitro (Vashee et al, 2003). In addition to their canonical roles in DNA replication, human ORC1 and CDC6 are involved directly in regulation of CCNE1 gene expression in mid G1 phase to influence the decision of whether cells will proliferate or not (Hossain and Stillman, 2016).…”

Section: Introductionmentioning

confidence: 99%

Cyclin binding Cy motifs have multiple activities in the initiation of DNA replication

Hossain

Bhalla

Stillman

2019

Preprint

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The initiation of DNA replication involves the cell cycle-dependent assembly and disassembly of protein complexes, including the Origin Recognition Complex (ORC) and CDC6 AAA+ ATPases. We report that multiple short, linear protein motifs (SLiMs) within intrinsically disordered regions in ORC1 and CDC6, including Cyclin-binding (Cy) motifs, mediate Cyclin-CDK dependent and independent protein-protein interactions, conditional on cell cycle phase. The ORC1 Cy motif mediates an auto-regulatory self-interaction, and the same Cy motif prevents CDC6 binding to ORC1 in mitosis, but then facilitates the destruction of ORC1 in S phase. In contrast, in G1, the CDC6 Cy motif promotes ORC1-CDC6 interaction independent of Cyclin-CDK protein phosphorylation. CDC6 interaction with ORC also requires a basic region of ORC1 that in yeast mediates ORC-DNA interactions. We also demonstrate that protein phosphatase 1 binds directly to a SLiM in ORC1, causing de-phosphorylation upon mitotic exit. Thus, Cy-motifs have wider roles, functioning as a ligand and as a degron.

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“…This provides buffering time for daughter cells to decide whether to proliferate or exit the cell cycle. 52 In G0 and early G1, Rb1-SUV39H1 mediated H3K9 methylation is also apparent on the DHFR promoter. As the cells progress toward G1/S, Rb1-SUV39H1 dissociates from E2F1 possibly due to hyper-phosphorylation of Rb1, which is correlated with hyperacetylation at the DHFR promoter.…”

Section: Function In Cellular Proliferationmentioning

confidence: 99%

“…Inhibits proliferation by repressing E2F1 target genes. [51][52][53] Inhibits adipogenic differentiation by repressing C/EBPa expression. 69 Overexpression in ERMS leads to delay in tumor initiation.…”

Section: Fundingmentioning

confidence: 99%

A drive in SUVs: From development to disease

2017

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Progression of cells through distinct phases of the cell cycle, and transition into out-of-cycling states, such as terminal differentiation and senescence, is accompanied by specific patterns of gene expression. These cell fate decisions are mediated not only by distinct transcription factors, but also chromatin modifiers that establish heritable epigenetic patterns. Lysine methyltransferases (KMTs) that mediate methylation marks on histone and non-histone proteins are now recognized as important regulators of gene expression in cycling and non-cycling cells. Among these, the SUV39 sub-family of KMTs, which includes SUV39H1, SUV39H2, G9a, GLP, SETDB1, and SETDB2, play a prominent role. In this review, we discuss their biochemical properties, sub-cellular localization and function in cell cycle, differentiation programs, and cellular senescence. We also discuss their aberrant expression in cancers, which exhibit de-regulation of cell cycle and differentiation.

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Opposing roles for DNA replication initiator proteins ORC1 and CDC6 in control of Cyclin E gene transcription

Cited by 30 publications

References 69 publications

The dNTP triphosphohydrolase activity of SAMHD1 persists during S-phase when the enzyme is phosphorylated at T592

The dNTP triphosphohydrolase activity of SAMHD1 persists during S-phase when the enzyme is phosphorylated at T592

Cyclin binding Cy motifs have multiple activities in the initiation of DNA replication

A drive in SUVs: From development to disease

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