Genotoxic Stress Targets Human Chk1 for Degradation by the Ubiquitin-Proteasome Pathway

Zhang, You Wei; Otterness, Diane M.; Chiang, Gary G.; Xie, Weilin; Liu, Yun‐Cai; Mercurio, Frank; Abraham, Robert T.

doi:10.1016/j.molcel.2005.07.019

Cited by 255 publications

(343 citation statements)

References 30 publications

Supporting

Mentioning

302

Contrasting

Order By: Relevance

“…46,47 Similar expression pattern of Chek1/p-Chek1 was seen in in vitro carcinogenesis model of mouse embryonic fibroblasts. In the later passage of the cells with malignant phenotype, reduced Chek1/p-Chek1 expression was seen.…”

Section: Cancer Geneticssupporting

confidence: 58%

Inactivation of CHEK1 and EI24 is associated with the development of invasive cervical carcinoma: Clinical and prognostic implications

Mazumder

Mitra

Singh

et al. 2011

Intl Journal of Cancer

View full text Add to dashboard Cite

To understand the importance of frequent deletion of chromosomal 11q23.3-24.3 region in cervical carcinogenesis, alterations (deletion/methylation/mutation/expression) of the candidate genes LOH11CR2A, EI24 and CHEK1 located in the region were analyzed in 29 cervical intraepithelial neoplasia (CIN), 112 cervical carcinoma (CACX) samples and two CACX cell lines. The deletion frequency of these genes was low in CIN than in CACX [CIN: CHEK1: 28%, EI24: 21%, LOH11CR2A: 15% and CACX: CHEK1: 51%, EI24: 41%, LOH11CR2A: 36%]. Similar trend was seen in promoter methylation of these genes [CIN: CHEK1: 10%, EI24: 3%, LOH11CR2A: 3% and CACX: CHEK1: 55%, EI24: 31%, LOH11CR2A: 14%]. Mutations of the genes are a rare event. Overall alterations (deletion and methylation) of CHEK1 and EI24 were associated with progression of CACX. Quantitative mRNA expression analysis showed reduced expression of the three genes in concordance to their molecular alterations. A shorter isoform of CHEK1 lacking exon 8, hence impaired in substrate binding capacity, was found in two samples. Immunohistochemical analysis showed nuclear expression of Chek1, p-Chek1 and Ei24 in tumor tissues, whereas the cell lines exhibited both nuclear and cytoplasmic expression of Chek1 and Ei24, as is also evident from Western blot analysis suggesting differential localization of the proteins. Alterations of CHEK1 and EI24 coupled with tumor stage and early sexual debut ( 19 years) predicted worst prognosis. Thus, our data suggest that inactivation of EI24 and CHEK1 through two independent mechanisms contributes to the development of CACX.Worldwide, cervical cancer (CACX) is one of the most deadly cancers among women and occupies second position among females in eastern India (Kolkata). 1 Infection by highrisk human papillomavirus (HPV) is a major cause of CACX 2 along with other etiological factors, such as use of oral contraceptives, precocious marriage, multiparity and smoking. 1,3 As HPV infections in most cases do not lead to cancer, and even a long latency period for the cancerous outcome in infected women suggests involvement of additional genetic alterations like functional inactivation of tumor suppressor genes (TSGs) or activation of oncogenes. 4 Investigations showing frequent chromosomal deletion in 11q23-q24 (20.4 Mb) in cervix, 5-7 breast, 8,9 lung, 10 colon 11 and ovarian 12 cancer and functional chromosome-transfer

show abstract

Section: Cancer Geneticssupporting

confidence: 58%

Inactivation of CHEK1 and EI24 is associated with the development of invasive cervical carcinoma: Clinical and prognostic implications

Mazumder

Mitra

Singh

et al. 2011

Intl Journal of Cancer

View full text Add to dashboard Cite

show abstract

“…7b). It has been previously shown that Chk1 is subjected to proteasome-dependent degradation following replication stress 42 . Timecourse analyses revealed that the overall rate of Chk1-protein degradation between 0 and 8 h after hydroxyurea treatment was increased 2.8 ± 0.6-fold (P = 0.002; calculated from three independent experiments) in HCLK2-depleted cells relative to control cells.…”

Section: Chk1 Instability Compromises Claspin Phosphorylation and Cdcmentioning

confidence: 99%

HCLK2 is essential for the mammalian S-phase checkpoint and impacts on Chk1 stability

et al. 2007

View full text Add to dashboard Cite

Here, we show that the human homologue of the Caenorhabditis elegans biological clock protein CLK-2 (HCLK2) associates with the S-phase checkpoint components ATR, ATRIP, claspin and Chk1. Consistent with a critical role in the S-phase checkpoint, HCLK2-depleted cells accumulate spontaneous DNA damage in S-phase, exhibit radio-resistant DNA synthesis, are impaired for damage-induced monoubiquitination of FANCD2 and fail to recruit FANCD2 and Rad51 (critical components of the Fanconi anaemia and homologous recombination pathways, respectively) to sites of replication stress. Although Thr 68 phosphorylation of the checkpoint effector kinase Chk2 remains intact in the absence of HCLK2, claspin phosphorylation and degradation of the checkpoint phosphatase Cdc25A are compromised following replication stress as a result of accelerated Chk1 degradation. ATR phosphorylation is known to both activate Chk1 and target it for proteolytic degradation, and depleting ATR or mutation of Chk1 at Ser 345 restored Chk1 protein levels in HCLK2-depleted cells. We conclude that HCLK2 promotes activation of the S-phase checkpoint and downstream repair responses by preventing unscheduled Chk1 degradation by the proteasome.The DNA damage response (DDR) is a complex process involving the orchestration of highly specialized cell-cycle checkpoints that need to be rapidly activated following the detection of damaged DNA. Each of these signalling cascades involves several unique and overlapping factors -classified as sensors, mediators, transducers and effectors -that ultimately lead to the spatio-temporal assembly of multi-protein complexes at the site of damage 1,2 . The functional importance of checkpoints in maintaining genome stability is highlighted by their conservation throughout eukaryotes. As such, defective checkpoint pathways in human cells leads to the accumulation of aberrant DNA and an increased risk of cancer progression, evident from the many human disease syndromes that result from defects in checkpoint factors 3,4 . Therefore, it is important to understand these complex mechanisms at the molecular level to further our knowledge of cancer progression and treatment.Checkpoints operate at the G1-S, S and G2-M boundaries of the cell cycle and are controlled by the ATM-Chk2 and ATR-Chk1 pathways. The S-phase checkpoint, which is under the control of the ATR-Chk1 pathway, has an essential role in maintaining replication-fork integrity during normal S-phase by preventing the collapse of stalled replication forks. The S-phase checkpoint also coordinates cell-cycle arrest and subsequent DNA-repair events when the replication fork encounters DNA damage 5,3,6 . Activation and recruitment of the Fanconi anaemia and homologous recombination-repair pathways to sites of replication stress requires an intact S-phase checkpoint 7 .Recent work in mouse models has highlighted a surprising, yet highly important link between biological clock proteins and the DDR 8,9 . It has been shown that two clock proteins, Per1 and Prd4, have integral roles...

show abstract

“…4A). Ubiquitin-dependent degradation may be a cause for a decrease in total Chk1 protein 6 to 9 h after checkpoint dysregulation (41). Cleavage of poly(ADP-ribose) polymerase confirmed increases in apoptosis (Fig.…”

Section: H2ax Phosphorylation Is Associated With the S-phase Checkpointmentioning

confidence: 82%

H2AX phosphorylation marks gemcitabine-induced stalled replication forks and their collapse upon S-phase checkpoint abrogation

Ewald

Sampath

Plunkett

2007

Molecular Cancer Therapeutics

182

172

View full text Add to dashboard Cite

Gemcitabine is a nucleoside analogue that is incorporated into replicating DNA, resulting in partial chain termination and stalling of replication forks. The histone variant H2AX is phosphorylated on Ser 139 (;-H2AX) and forms nuclear foci at sites of DNA damage. Here, we characterize the concentration-and time-dependent phosphorylation of H2AX in response to gemcitabine-induced stalled replication forks. The number of ;-H2AX foci increased with time up to 2 to 6 h after exposure to gemcitabine, whereas longer exposures did not cause greater phosphorylation or increase cell death. The percentage of ;-H2AX -positive cells increased with concentrations of gemcitabine up to 0.1 Mmol/L, and ;-H2AX was most evident in the S-phase fraction. Phosphorylation of ataxia-telangiectasia mutated (ATM) on Ser 1981 was also associated with S-phase cells and colocalized in the nucleus with phosphorylated H2AX foci after gemcitabine exposure.

show abstract

Genotoxic Stress Targets Human Chk1 for Degradation by the Ubiquitin-Proteasome Pathway

Cited by 255 publications

References 30 publications

Inactivation of CHEK1 and EI24 is associated with the development of invasive cervical carcinoma: Clinical and prognostic implications

Inactivation of CHEK1 and EI24 is associated with the development of invasive cervical carcinoma: Clinical and prognostic implications

HCLK2 is essential for the mammalian S-phase checkpoint and impacts on Chk1 stability

H2AX phosphorylation marks gemcitabine-induced stalled replication forks and their collapse upon S-phase checkpoint abrogation

Contact Info

Product

Resources

About