Centrosomal Localization of Cyclin E-Cdk2 Is Required for Initiation of DNA Synthesis

Cyclin E1 is essential for the reentry of quiescent cells into the cell cycle. When hypomorphic mutant Myb mice (Myb Plt4 ) were examined, it was noted that Cyclin E1 (Ccne1) expression was reduced. Furthermore, the induction of Ccne1 in recovering intestinal epithelia following radiation-induced damage was ablated in Myb-mutant mice. These data prompted us to investigate whether Myb directly regulated Ccne1 and to examine whether elevated Myb in colorectal cancer is responsible for Cyclin E1-driven tumor growth. Here, it was found that Myb/ MYB and Ccne1/CCNE1 expressions were coupled in both mouse and human adenomas. In addition, the low molecular weight Cyclin E1 was the predominant form in intestinal crypts and adenomatous polyposis coli (Apc)-mutant adenomas. Chromatin immunoprecipitation (ChIP) analysis confirmed that Myb bound directly to the Ccne1 promoter and regulated its endogenous expression. In contrast, Myb Plt4 served as a dominant-negative factor that inhibited wild-type Myb and this was not apparently compensated for by the transcription factor E2F1 in intestinal epithelial cells. Myb Plt4/Plt4 mice died prematurely on an Apc Min/þ background associated with hematopoietic defects, including a myelodysplasia; nevertheless, Apc Min/þ mice were protected from intestinal tumorigenesis when crossed to Myb Plt4/þ mice. Knockdown of CCNE1 transcript in murine colorectal cancer cells stabilized chromosome ploidy and decreased tumor formation. These data suggest that Cyclin E1 expression is Myb dependent in normal and transformed intestinal epithelial cells, consistent with a cell-cycle progression and chromosome instability role in cancer.Implications: This study demonstrates that Myb regulates Cyclin E1 expression in normal gastrointestinal tract epithelial cells and is required during intestinal tumorigenesis. Mol Cancer Res; 13(8); 1185-96. Ó2015 AACR.

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“…6A-C). This finding is consistent with other reports that have shown Ccne1 levels affect karyotype stability (34,35).…”

Section: Cyclin E1 Knockdown Effects On Chromosome Stabilitysupporting

confidence: 94%

Defective Myb Function Ablates Cyclin E1 Expression and Perturbs Intestinal Carcinogenesis

Cheasley

Pereira

Sampurno

et al. 2015

Molecular Cancer Research

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“…It has been reported that the role of centrosomal cyclin E in initiation of DNA synthesis is dependent on an active CDK2-cyclin E complex [6]. However, our results show that centrosomal Plk1 facilitates DNA replication in a kinase activity-independent manner (Figures 4 and 6), suggesting a previously uncharacterized function of Plk1 during DNA replication.…”

Section: Discussioncontrasting

confidence: 56%

“…Overexpression of the centrosomal localization signal of cyclin E prevents endogenous cyclin E from localizing to centrosomes, inhibits the initiation of DNA synthesis, and reduces the loading of initiation factor Cdc45 to chromatin [6][7][8]24], indicating that a signal generated from centrosomes may be transmitted to the DNA replication complex in chromatin. Theoretically, there should be mutual communications between centrosomes and the nucleus to coordinate both centrosome and DNA events throughout the entire cell cycle.…”

Section: Discussionmentioning

confidence: 99%

“…Removal of centrosomes by microsurgery either in interphase cells or in prophase cells ultimately results in failure of these cells to enter into subsequent S-phase, as does depletion of some centrosome-associated proteins by RNA interference (RNAi) [3][4][5], implying a possible centrosomal checkpoint at the G1/S boundary. This hypothesis is further supported by the fact that either centrosomal cyclin E or A is essential for S-phase entry [6][7][8]. Some key mitotic regulators, such as cyclin-dependent kinase 1 (CDK1), Aurora A and polo-like kinase 1 (Plk1), are recruited to centrosomes at the G2/M transition, where they are fully activated, presumably through centrosome-localized phosphatase Cdc25B [2,6,9,10], suggesting an important role of centrosomes in mitotic entry.…”

Section: Introductionmentioning

confidence: 96%

“…This hypothesis is further supported by the fact that either centrosomal cyclin E or A is essential for S-phase entry [6][7][8]. Some key mitotic regulators, such as cyclin-dependent kinase 1 (CDK1), Aurora A and polo-like kinase 1 (Plk1), are recruited to centrosomes at the G2/M transition, where they are fully activated, presumably through centrosome-localized phosphatase Cdc25B [2,6,9,10], suggesting an important role of centrosomes in mitotic entry. However, little is known about the role of centrosomes during S-phase progression.…”

Section: Introductionmentioning

confidence: 96%

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Centrosomal protein FOR20 is essential for S-phase progression by recruiting Plk1 to centrosomes

et al. 2013

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Centrosomes are required for efficient cell cycle progression mainly by orchestrating microtubule dynamics and facilitating G1/S and G2/M transitions. However, the role of centrosomes in S-phase progression is largely unknown. Here, we report that depletion of FOR20 (FOP-related protein of 20 kDa), a conserved centrosomal protein, inhibits S-phase progression and prevents targeting of Plk1 (polo-like kinase 1) to centrosomes, where FOR20 interacts with Plk1. Ablation of Plk1 also significantly induces S-phase defects, which are reversed by ectopic expression of Plk1, even a kinase-dead mutant, but not a mutant that fails to localize to centrosomes. Exogenous expression of centrosome-tethered Plk1, but not wild-type Plk1, overrides FOR20 depletion-induced S-phase defects independently of its kinase activity. Thus, these data indicate that recruitment of Plk1 to centrosomes by FOR20 may act as a signal to license efficient progression of S-phase. This represents a hitherto uncharacterized role of centrosomes in cell cycle regulation.

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LRWD1 Regulates Microtubule Nucleation and Proper Cell Cycle Progression in the Human Testicular Embryonic Carcinoma Cells

Wang

Hong

Syu

et al. 2017

J of Cellular Biochemistry

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Leucine-rich repeats and WD repeat domain containing protein 1 (LRWD1) is a testis-specific protein that mainly expressed in the sperm neck where centrosome is located. By using microarray analysis, LRWD1 is identified as a putative gene that involved in spermatogenesis. However, its role in human male germ cell development has not been extensively studied. When checking in the semen of patients with asthenozoospermia, teratozoospermia, and asthenoteratozoospermia, the level of LRWD1 in the sperm neck was significantly reduced with a defective neck or tail. When checking the sub-cellular localization of LRWD1 in the cells, we found that LRWD1 resided in the centrosome and its centrosomal residency was independent of microtubule transportation in NT2/D1, the human testicular embryonic carcinoma, cell line. Depletion of LRWD1 did not induce centrosome re-duplication but inhibited microtubule nucleation. In addition, the G1 arrest were observed in LRWD1 deficient NT2/D1 cells. Upon LRWD1 depletion, the levels of cyclin E, A, and phosphorylated CDK2, were reduced. Overexpression of LRWD1 promoted cell proliferation in NT2/D1, HeLa, and 239T cell lines. In addition, we also observed that autophagy was activated in LRWD1 deficient cells and inhibition of autophagy by chloroquine or bafilomycin A1 promoted cell death when LRWD1 was depleted. Thus, we found a novel function of LRWD1 in controlling microtubule nucleation and cell cycle progression in the human testicular embryonic carcinoma cells.

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Centrosomal Localization of Cyclin E-Cdk2 Is Required for Initiation of DNA Synthesis

Cited by 53 publications

References 33 publications

Defective Myb Function Ablates Cyclin E1 Expression and Perturbs Intestinal Carcinogenesis

Defective Myb Function Ablates Cyclin E1 Expression and Perturbs Intestinal Carcinogenesis

Centrosomal protein FOR20 is essential for S-phase progression by recruiting Plk1 to centrosomes

LRWD1 Regulates Microtubule Nucleation and Proper Cell Cycle Progression in the Human Testicular Embryonic Carcinoma Cells

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