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Chowdhury SP, Solley SC, Polishchuk E, Bacal J, Conrad JE, Gardner BM, Acosta-Alvear D, Zappa F. Baseline unfolded protein response signaling adjusts the timing of the mammalian cell cycle. Mol Biol Cell 2024; 35:br12. [PMID: 38656789 PMCID: PMC11238080 DOI: 10.1091/mbc.e23-11-0419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 04/26/2024] Open
Abstract
The endoplasmic reticulum (ER) is a single-copy organelle that cannot be generated de novo, suggesting coordination between the mechanisms overseeing ER integrity and those controlling the cell cycle to maintain organelle inheritance. The Unfolded Protein Response (UPR) is a conserved signaling network that regulates ER homeostasis. Here, we show that pharmacological and genetic inhibition of the UPR sensors IRE1, ATF6, and PERK in unstressed cells delays the cell cycle, with PERK inhibition showing the most penetrant effect, which was associated with a slowdown of the G1-to-S/G2 transition. Treatment with the small molecule ISRIB to bypass the effects of PERK-dependent phosphorylation of the translation initiation factor eIF2α had no such effect, suggesting that cell cycle timing depends on PERK's kinase activity but is independent of eIF2α phosphorylation. Using complementary light and electron microscopy and flow cytometry-based analyses, we also demonstrate that the ER enlarges before mitosis. Together, our results suggest coordination between UPR signaling and the cell cycle to maintain ER physiology during cell division.
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Affiliation(s)
- Soham P. Chowdhury
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106
| | - Sabrina C. Solley
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106
| | - Elena Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Naples, Italy
| | - Julien Bacal
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106
| | - Julia E. Conrad
- Altos Labs Bay Area Institute of Science, Altos Labs, Redwood City, CA 94065
| | - Brooke M. Gardner
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106
| | - Diego Acosta-Alvear
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106
| | - Francesca Zappa
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106
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2
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Zhang K, Zou Y, Shan M, Pan Z, Ju J, Liu J, Ji Y, Sun S. Arf1 GTPase Regulates Golgi-Dependent G2/M Transition and Spindle Organization in Oocyte Meiosis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2303009. [PMID: 38014604 PMCID: PMC10811507 DOI: 10.1002/advs.202303009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/18/2023] [Indexed: 11/29/2023]
Abstract
ADP-ribosylation factor 1 (Arf1) is a small GTPase belonging to the Arf family. As a molecular switch, Arf1 is found to regulate retrograde and intra-Golgi transport, plasma membrane signaling, and organelle function during mitosis. This study aimed to explore the noncanonical roles of Arf1 in cell cycle regulation and cytoskeleton dynamics in meiosis with a mouse oocyte model. Arf1 accumulated in microtubules during oocyte meiosis, and the depletion of Arf1 led to the failure of polar body extrusion. Unlike mitosis, it finds that Arf1 affected Myt1 activity for cyclin B1/CDK1-based G2/M transition, which disturbed oocyte meiotic resumption. Besides, Arf1 modulated GM130 for the dynamic changes in the Golgi apparatus and Rab35-based vesicle transport during meiosis. Moreover, Arf1 is associated with Ran GTPase for TPX2 expression, further regulating the Aurora A-polo-like kinase 1 pathway for meiotic spindle assembly and microtubule stability in oocytes. Further, exogenous Arf1 mRNA supplementation can significantly rescue these defects. In conclusion, results reported the noncanonical functions of Arf1 in G2/M transition and meiotic spindle organization in mouse oocytes.
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Affiliation(s)
- Kun‐Huan Zhang
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Yuan‐Jing Zou
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Meng‐Meng Shan
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Zhen‐Nan Pan
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Jia‐Qian Ju
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Jing‐Cai Liu
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Yi‐Ming Ji
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
| | - Shao‐Chen Sun
- College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing210095China
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3
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Li J, Lu J, Xu M, Yang S, Yu T, Zheng C, Huang X, Pan Y, Chen Y, Long J, Zhang C, Huang H, Dai Q, Li B, Wang W, Yao S, Pan C. ODF2L acts as a synthetic lethal partner with WEE1 inhibition in epithelial ovarian cancer models. J Clin Invest 2023; 133:161544. [PMID: 36378528 PMCID: PMC9843051 DOI: 10.1172/jci161544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
WEE1 has emerged as an attractive target in epithelial ovarian cancer (EOC), but how EOC cells may alter their sensitivity to WEE1 inhibition remains unclear. Here, through a cell cycle machinery-related gene RNAi screen, we found that targeting outer dense fiber of sperm tails 2-like (ODF2L) was a synthetic lethal partner with WEE1 kinase inhibition in EOC cells. Knockdown of ODF2L robustly sensitized cells to treatment with the WEE1 inhibitor AZD1775 in EOC cell lines in vitro as well as in xenografts in vivo. Mechanistically, the increased sensitivity to WEE1 inhibition upon ODF2L loss was accompanied by accumulated DNA damage. ODF2L licensed the recruitment of PKMYT1, a functionally redundant kinase of WEE1, to the CDK1-cyclin B complex and thus restricted the activity of CDK1 when WEE1 was inhibited. Clinically, upregulation of ODF2L correlated with CDK1 activity, DNA damage levels, and sensitivity to WEE1 inhibition in patient-derived EOC cells. Moreover, ODF2L levels predicted the response to WEE1 inhibition in an EOC patient-derived xenograft model. Combination treatment with tumor-targeted lipid nanoparticles that packaged ODF2L siRNA and AZD1775 led to the synergistic attenuation of tumor growth in the ID8 ovarian cancer syngeneic mouse model. These data suggest that WEE1 inhibition is a promising precision therapeutic strategy for EOC cells expressing low levels of ODF2L.
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Affiliation(s)
- Jie Li
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Jingyi Lu
- Department of Biochemistry and Molecular Biology, Zhongshan School of Medicine, and
| | - Manman Xu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Shiyu Yang
- Department of Biochemistry and Molecular Biology, Zhongshan School of Medicine, and
| | - Tiantian Yu
- Department of Biochemistry and Molecular Biology, Zhongshan School of Medicine, and
| | - Cuimiao Zheng
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xi Huang
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yuwen Pan
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Yangyang Chen
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Junming Long
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Chunyu Zhang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Hua Huang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Qingyuan Dai
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Bo Li
- Department of Biochemistry and Molecular Biology, Zhongshan School of Medicine, and,Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Wei Wang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Shuzhong Yao
- Department of Obstetrics and Gynecology, The First Affiliated Hospital
| | - Chaoyun Pan
- Department of Biochemistry and Molecular Biology, Zhongshan School of Medicine, and,Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
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4
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Ngoi NYL, Westin SN, Yap TA. Targeting the DNA damage response beyond poly(ADP-ribose) polymerase inhibitors: novel agents and rational combinations. Curr Opin Oncol 2022; 34:559-569. [PMID: 35787597 PMCID: PMC9371461 DOI: 10.1097/cco.0000000000000867] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Poly(ADP-ribose) polymerase (PARP) inhibitors have transformed treatment paradigms in multiple cancer types defined by homologous recombination deficiency (HRD) and have become the archetypal example of synthetic lethal targeting within the DNA damage response (DDR). Despite this success, primary and acquired resistance to PARP inhibition inevitability threaten the efficacy and durability of response to these drugs. Beyond PARP inhibitors, recent advances in large-scale functional genomic screens have led to the identification of a steadily growing list of genetic dependencies across the DDR landscape. This has led to a wide array of novel synthetic lethal targets and corresponding inhibitors, which hold promise to widen the application of DDR inhibitors beyond HRD and potentially address PARP inhibitor resistance. RECENT FINDINGS In this review, we describe key synthetic lethal interactions that have been identified across the DDR landscape, summarize the early phase clinical development of the most promising DDR inhibitors, and highlight relevant combinations of DDR inhibitors with chemotherapy and other novel cancer therapies, which are anticipated to make an impact in rationally selected patient populations. SUMMARY The DDR landscape holds multiple opportunities for synthetic lethal targeting with multiple novel DDR inhibitors being evaluated on early phase clinical trials. Key challenges remain in optimizing the therapeutic window of ATR and WEE1 inhibitors as monotherapy and in combination approaches.
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Affiliation(s)
- Natalie Y L Ngoi
- Department of Investigational Cancer Therapeutics, Division of Cancer Medicine
| | - Shannon N Westin
- Department of Gynecologic Oncology and Reproductive Medicine, Division of Surgery
| | - Timothy A Yap
- Department of Investigational Cancer Therapeutics, Division of Cancer Medicine
- The Institute for Applied Cancer Science
- Khalifa Institute for Personalized Cancer Therapy, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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5
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Proteomic profiling reveals neuronal ion channel dysregulation and cellular responses to DNA damage-induced cell cycle arrest and senescence in human neuroblastoma SH-SY5Y cells exposed to cypermethrin. Neurotoxicology 2022; 93:71-83. [PMID: 36063984 DOI: 10.1016/j.neuro.2022.08.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/27/2022] [Accepted: 08/28/2022] [Indexed: 11/20/2022]
Abstract
Cypermethrin (CYP), a synthetic pyrethroid of class II, is widely used as a pesticide worldwide. The primary target of cypermethrin is a voltage-gated sodium channel. The neurotoxicity of CYP has been extensively studied in terms of affecting neuronal development, increasing cellular oxidative stress, and apoptosis. However, little is known about how it affects the expression of channel proteins involved in synaptic transmission, as well as the effects of cypermethrin on DNA damage and cell cycle processes. We found that the ligand and voltage-gated calcium channels and proteins involved in synaptic transmission including NMDA 1 receptor subunit, alpha 1A-voltage-dependent calcium channel, synaptotagmin-17, and synaptojanin-2 were downregulated in CYP-treated cells. After 48h of CYP exposure, cell viability was reduced with flattened and enlarged morphology. The levels of 23 proteins regulating cell cycle processes were altered in CYP-treated cells, according to a proteomic study. The cell cycle analysis showed elevated G0/G1 cell cycle arrest and DNA fragmentation at the sub-G0 stage after CYP exposure. CYP treatment also increased senescence-associated β-galactosidase positive cells, DNA damage, and apoptotic markers. Taken together, the current study showed that cypermethrin exposure caused DNA damage and hastened cellular senescence and apoptosis via disrupting cell cycle regulation. In addition, despite its primary target sodium channel, CYP might cause synaptic dysfunction via the downregulation of synaptic proteins and dysregulation of synapse-associated ion channels.
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6
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Gallo D, Young JTF, Fourtounis J, Martino G, Álvarez-Quilón A, Bernier C, Duffy NM, Papp R, Roulston A, Stocco R, Szychowski J, Veloso A, Alam H, Baruah PS, Fortin AB, Bowlan J, Chaudhary N, Desjardins J, Dietrich E, Fournier S, Fugère-Desjardins C, Goullet de Rugy T, Leclaire ME, Liu B, Bhaskaran V, Mamane Y, Melo H, Nicolas O, Singhania A, Szilard RK, Tkáč J, Yin SY, Morris SJ, Zinda M, Marshall CG, Durocher D. CCNE1 amplification is synthetic lethal with PKMYT1 kinase inhibition. Nature 2022; 604:749-756. [PMID: 35444283 PMCID: PMC9046089 DOI: 10.1038/s41586-022-04638-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 03/14/2022] [Indexed: 12/13/2022]
Abstract
Amplification of the CCNE1 locus on chromosome 19q12 is prevalent in multiple tumour types, particularly in high-grade serous ovarian cancer, uterine tumours and gastro-oesophageal cancers, where high cyclin E levels are associated with genome instability, whole-genome doubling and resistance to cytotoxic and targeted therapies1-4. To uncover therapeutic targets for tumours with CCNE1 amplification, we undertook genome-scale CRISPR-Cas9-based synthetic lethality screens in cellular models of CCNE1 amplification. Here we report that increasing CCNE1 dosage engenders a vulnerability to the inhibition of the PKMYT1 kinase, a negative regulator of CDK1. To inhibit PKMYT1, we developed RP-6306, an orally bioavailable and selective inhibitor that shows single-agent activity and durable tumour regressions when combined with gemcitabine in models of CCNE1 amplification. RP-6306 treatment causes unscheduled activation of CDK1 selectively in CCNE1-overexpressing cells, promoting early mitosis in cells undergoing DNA synthesis. CCNE1 overexpression disrupts CDK1 homeostasis at least in part through an early activation of the MMB-FOXM1 mitotic transcriptional program. We conclude that PKMYT1 inhibition is a promising therapeutic strategy for CCNE1-amplified cancers.
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Affiliation(s)
- David Gallo
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | | | | | | | - Alejandro Álvarez-Quilón
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | | | - Robert Papp
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | - Rino Stocco
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | | | - Hunain Alam
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | | | | | - Natasha Chaudhary
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | | | | | | | | | - Theo Goullet de Rugy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | - Bingcan Liu
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | - Yael Mamane
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | - Henrique Melo
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | | | | | - Rachel K Szilard
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Ján Tkáč
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Shou Yun Yin
- Repare Therapeutics, Saint-Laurent, Quebec, Canada
| | | | | | | | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
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7
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Bukhari AB, Chan GK, Gamper AM. Targeting the DNA Damage Response for Cancer Therapy by Inhibiting the Kinase Wee1. Front Oncol 2022; 12:828684. [PMID: 35251998 PMCID: PMC8891215 DOI: 10.3389/fonc.2022.828684] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/21/2022] [Indexed: 12/15/2022] Open
Abstract
Cancer cells typically heavily rely on the G2/M checkpoint to survive endogenous and exogenous DNA damage, such as genotoxic stress due to genome instability or radiation and chemotherapy. The key regulator of the G2/M checkpoint, the cyclin-dependent kinase 1 (CDK1), is tightly controlled, including by its phosphorylation state. This posttranslational modification, which is determined by the opposing activities of the phosphatase cdc25 and the kinase Wee1, allows for a more rapid response to cellular stress than via the synthesis or degradation of modulatory interacting proteins, such as p21 or cyclin B. Reducing Wee1 activity results in ectopic activation of CDK1 activity and drives premature entry into mitosis with unrepaired or under-replicated DNA and causing mitotic catastrophe. Here, we review efforts to use small molecule inhibitors of Wee1 for therapeutic purposes, including strategies to combine Wee1 inhibition with genotoxic agents, such as radiation therapy or drugs inducing replication stress, or inhibitors of pathways that show synthetic lethality with Wee1. Furthermore, it become increasingly clear that Wee1 inhibition can also modulate therapeutic immune responses. We will discuss the mechanisms underlying combination treatments identifying both cell intrinsic and systemic anti-tumor activities.
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8
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Rajanala K, Klayman LM, Wedegaertner PB. Gβγ regulates mitotic Golgi fragmentation and G2/M cell cycle progression. Mol Biol Cell 2021; 32:br2. [PMID: 34260268 PMCID: PMC8684744 DOI: 10.1091/mbc.e21-04-0175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins (αβγ) function at the cytoplasmic surface of a cell’s plasma membrane to transduce extracellular signals into cellular responses. However, numerous studies indicate that G proteins also play noncanonical roles at unique intracellular locations. Previous work has established that G protein βγ subunits (Gβγ) regulate a signaling pathway on the cytoplasmic surface of Golgi membranes that controls the exit of select protein cargo. Now, we demonstrate a novel role for Gβγ in regulating mitotic Golgi fragmentation, a key checkpoint of the cell cycle that occurs in the late G2 phase. We show that small interfering RNA–mediated depletion of Gβ1 and Gβ2 in synchronized cells causes a decrease in the number of cells with fragmented Golgi in late G2 and a delay of entry into mitosis and progression through G2/M. We also demonstrate that during G2/M Gβγ acts upstream of protein kinase D and regulates the phosphorylation of the Golgi structural protein GRASP55. Expression of Golgi-targeted GRK2ct, a Gβγ-sequestering protein used to inhibit Gβγ signaling, also causes a decrease in Golgi fragmentation and a delay in mitotic progression. These results highlight a novel role for Gβγ in regulation of Golgi structure.
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Affiliation(s)
- Kalpana Rajanala
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Sidney Kimmel Medical College, Philadelphia, PA 19107
| | - Lauren M Klayman
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Sidney Kimmel Medical College, Philadelphia, PA 19107
| | - Philip B Wedegaertner
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Sidney Kimmel Medical College, Philadelphia, PA 19107
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9
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Ghelli Luserna di Rorà A, Cerchione C, Martinelli G, Simonetti G. A WEE1 family business: regulation of mitosis, cancer progression, and therapeutic target. J Hematol Oncol 2020; 13:126. [PMID: 32958072 PMCID: PMC7507691 DOI: 10.1186/s13045-020-00959-2] [Citation(s) in RCA: 115] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/02/2020] [Indexed: 01/05/2023] Open
Abstract
The inhibition of the DNA damage response (DDR) pathway in the treatment of cancer has recently gained interest, and different DDR inhibitors have been developed. Among them, the most promising ones target the WEE1 kinase family, which has a crucial role in cell cycle regulation and DNA damage identification and repair in both nonmalignant and cancer cells. This review recapitulates and discusses the most recent findings on the biological function of WEE1/PKMYT1 during the cell cycle and in the DNA damage repair, with a focus on their dual role as tumor suppressors in nonmalignant cells and pseudo-oncogenes in cancer cells. We here report the available data on the molecular and functional alterations of WEE1/PKMYT1 kinases in both hematological and solid tumors. Moreover, we summarize the preclinical information on 36 chemo/radiotherapy agents, and in particular their effect on cell cycle checkpoints and on the cellular WEE1/PKMYT1-dependent response. Finally, this review outlines the most important pre-clinical and clinical data available on the efficacy of WEE1/PKMYT1 inhibitors in monotherapy and in combination with chemo/radiotherapy agents or with other selective inhibitors currently used or under evaluation for the treatment of cancer patients.
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Affiliation(s)
- Andrea Ghelli Luserna di Rorà
- Biosciences Laboratory (Onco-hematology Unit), Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Via P. Maroncelli 40, 47014, Meldola, FC, Italy
| | - Claudio Cerchione
- Biosciences Laboratory (Onco-hematology Unit), Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Via P. Maroncelli 40, 47014, Meldola, FC, Italy
| | - Giovanni Martinelli
- Biosciences Laboratory (Onco-hematology Unit), Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Via P. Maroncelli 40, 47014, Meldola, FC, Italy
| | - Giorgia Simonetti
- Biosciences Laboratory (Onco-hematology Unit), Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Via P. Maroncelli 40, 47014, Meldola, FC, Italy.
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10
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Zhang QY, Chen XQ, Liu XC, Wu DM. PKMYT1 Promotes Gastric Cancer Cell Proliferation and Apoptosis Resistance. Onco Targets Ther 2020; 13:7747-7757. [PMID: 32801781 PMCID: PMC7414979 DOI: 10.2147/ott.s255746] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/15/2020] [Indexed: 01/10/2023] Open
Abstract
Background Abnormal expression of protein kinase membrane associated tyrosine/threonine 1 (PKMYT1) is closely associated with multiple types of cancers. In the present study, we examined the roles of PKMYT1 in gastric cancer (GC) progression. Methods We examined the expression status of PKMYT1 in GC tissues and cell lines. Meanwhile, short hairpin RNA (shRNA) was used to inhibit the endogenous expression of PKMYT1 in GC cells. Then we analyzed the effect of PKMYT1 on the malignant biological behavior of GC cells by in vitro and in vivo experiments. Results The findings showed high PKMYT1 expressions in GC tissues as well as a positive correlation between PKMYT1 expression and prognosis of patients with GC. Additional findings also revealed that PKMYT1 silencing significantly enhanced apoptosis and inhibited GC cell proliferation. In vivo, the silence of PKMYT1 inhibits tumor growth. Further analysis showed that the increase in PKMYT1 expressions led to malignant biological behavior through activation of the MAPK signaling pathway. Conclusion Our data suggested that PKMYT1 promotes cell proliferation and apoptosis resistance in GC cells by activating the MAPK signaling pathway, making it a potential therapeutic target for GC.
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Affiliation(s)
- Qi-Yong Zhang
- Department of Gastroenterology, The First People's Hospital of Lanzhou, Lanzhou City, Gansu 730050, People's Republic of China
| | - Xiao-Qin Chen
- Department of Gastroenterology, The First People's Hospital of Lanzhou, Lanzhou City, Gansu 730050, People's Republic of China
| | - Xiong-Chang Liu
- Department of Gastroenterology, The First People's Hospital of Lanzhou, Lanzhou City, Gansu 730050, People's Republic of China
| | - De-Ming Wu
- Department of Gastroenterology, The First People's Hospital of Lanzhou, Lanzhou City, Gansu 730050, People's Republic of China
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11
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Lewis CW, Bukhari AB, Xiao EJ, Choi WS, Smith JD, Homola E, Mackey JR, Campbell SD, Gamper AM, Chan GK. Upregulation of Myt1 Promotes Acquired Resistance of Cancer Cells to Wee1 Inhibition. Cancer Res 2019; 79:5971-5985. [PMID: 31594837 DOI: 10.1158/0008-5472.can-19-1961] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/04/2019] [Accepted: 10/04/2019] [Indexed: 11/16/2022]
Abstract
Adavosertib (also known as AZD1775 or MK1775) is a small-molecule inhibitor of the protein kinase Wee1, with single-agent activity in multiple solid tumors, including sarcoma, glioblastoma, and head and neck cancer. Adavosertib also shows promising results in combination with genotoxic agents such as ionizing radiation or chemotherapy. Previous studies have investigated molecular mechanisms of primary resistance to Wee1 inhibition. Here, we investigated mechanisms of acquired resistance to Wee1 inhibition, focusing on the role of the Wee1-related kinase Myt1. Myt1 and Wee1 kinases were both capable of phosphorylating and inhibiting Cdk1/cyclin B, the key enzymatic complex required for mitosis, demonstrating their functional redundancy. Ectopic activation of Cdk1 induced aberrant mitosis and cell death by mitotic catastrophe. Cancer cells with intrinsic adavosertib resistance had higher levels of Myt1 compared with sensitive cells. Furthermore, cancer cells that acquired resistance following short-term adavosertib treatment had higher levels of Myt1 compared with mock-treated cells. Downregulating Myt1 enhanced ectopic Cdk1 activity and restored sensitivity to adavosertib. These data demonstrate that upregulating Myt1 is a mechanism by which cancer cells acquire resistance to adavosertib. SIGNIFICANCE: Myt1 is a candidate predictive biomarker of acquired resistance to the Wee1 kinase inhibitor adavosertib.
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Affiliation(s)
- Cody W Lewis
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Amirali B Bukhari
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Edric J Xiao
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Won-Shik Choi
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Joanne D Smith
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Ellen Homola
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - John R Mackey
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Medical Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Shelagh D Campbell
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Armin M Gamper
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Gordon K Chan
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada. .,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
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12
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Crncec A, Hochegger H. Triggering mitosis. FEBS Lett 2019; 593:2868-2888. [PMID: 31602636 DOI: 10.1002/1873-3468.13635] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/07/2019] [Accepted: 10/07/2019] [Indexed: 12/28/2022]
Abstract
Entry into mitosis is triggered by the activation of cyclin-dependent kinase 1 (Cdk1). This simple reaction rapidly and irreversibly sets the cell up for division. Even though the core step in triggering mitosis is so simple, the regulation of this cellular switch is highly complex, involving a large number of interconnected signalling cascades. We do have a detailed knowledge of most of the components of this network, but only a poor understanding of how they work together to create a precise and robust system that ensures that mitosis is triggered at the right time and in an orderly fashion. In this review, we will give an overview of the literature that describes the Cdk1 activation network and then address questions relating to the systems biology of this switch. How is the timing of the trigger controlled? How is mitosis insulated from interphase? What determines the sequence of events, following the initial trigger of Cdk1 activation? Which elements ensure robustness in the timing and execution of the switch? How has this system been adapted to the high levels of replication stress in cancer cells?
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Affiliation(s)
- Adrijana Crncec
- Genome Damage and Stability Centre, University of Sussex, Brighton, UK
| | - Helfrid Hochegger
- Genome Damage and Stability Centre, University of Sussex, Brighton, UK
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13
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Yoshitome S, Aiba Y, Yuge M, Furuno N, Watanabe M, Nakajo N. Involvement of Myt1 kinase in the G2 phase of the first cell cycle in Xenopus laevis. Biochem Biophys Res Commun 2019; 515:139-144. [PMID: 31128913 DOI: 10.1016/j.bbrc.2019.05.104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 05/14/2019] [Indexed: 10/26/2022]
Abstract
During cleavage of Xenopus laevis, the first mitotic cell cycle immediately following fertilization is approximately 90 min and consists of S, G2, and M phases. In contrast, the subsequent eleven cell cycles are approximately 30 min and consist mostly of S and M phases. The balance between Cdc25 and Wee1A/Myt1 is thought to be crucial for Xenopus first cell cycle progression; however, the role of Myt1 in this period has not been fully investigated. In this study, we examined the roles of Myt1, Wee1A, and Cdc25A in the first cell cycle of Xenopus laevis. Inhibition of Cdc25A with antisense morpholino oligonucleotides lengthened the duration of the first cell cycle to some extent, whereas it was slightly shortened by ectopic Cdc25A expression, suggesting that the low concentration of Cdc25A during the first cell cycle does not fully account for the long duration of this cycle. Using the Wee1A antisense morpholino oligonucleotide and neutralizing antibody against Myt1, we found that Myt1 phosphorylates and inhibits Cdk1 much more effectively than Wee1A during the first cell cycle in Xenopus. Taken together, these results suggest that the activity of Myt1 is predominantly responsible for the duration of the long G2 phase in the first mitotic cell cycle in Xenopus.
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Affiliation(s)
- Satoshi Yoshitome
- Department of Biology, Graduate School of Sciences, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395, Japan; Department of Enviromental Science, International College of Arts and Sciences, Fukuoka Women's University, Kasumigaoka 1-1-1, Higashi-Ku, Fukuoka, 813-8529, Japan.
| | - Yukito Aiba
- Department of Biology, Graduate School of Sciences, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Masahiro Yuge
- Department of Enviromental Science, International College of Arts and Sciences, Fukuoka Women's University, Kasumigaoka 1-1-1, Higashi-Ku, Fukuoka, 813-8529, Japan
| | - Nobuaki Furuno
- Amphibian Research Center, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, 739-8526, Japan
| | - Minoru Watanabe
- Institute of Liberal Arts and Sciences, Tokushima University, Minamijosanjima-cho 1-1, Tokushima, 770-8502, Japan
| | - Nobushige Nakajo
- Department of Biology, Graduate School of Sciences, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395, Japan
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14
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Lafarga V, Sung HM, Haneke K, Roessig L, Pauleau AL, Bruer M, Rodriguez-Acebes S, Lopez-Contreras AJ, Gruss OJ, Erhardt S, Mendez J, Fernandez-Capetillo O, Stoecklin G. TIAR marks nuclear G2/M transition granules and restricts CDK1 activity under replication stress. EMBO Rep 2019; 20:e46224. [PMID: 30538118 PMCID: PMC6322364 DOI: 10.15252/embr.201846224] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 11/06/2018] [Accepted: 11/08/2018] [Indexed: 12/20/2022] Open
Abstract
The G2/M checkpoint coordinates DNA replication with mitosis and thereby prevents chromosome segregation in the presence of unreplicated or damaged DNA Here, we show that the RNA-binding protein TIAR is essential for the G2/M checkpoint and that TIAR accumulates in nuclear foci in late G2 and prophase in cells suffering from replication stress. These foci, which we named G2/M transition granules (GMGs), occur at low levels in normally cycling cells and are strongly induced by replication stress. In addition to replication stress response proteins, GMGs contain factors involved in RNA metabolism as well as CDK1. Depletion of TIAR accelerates mitotic entry and leads to chromosomal instability in response to replication stress, in a manner that can be alleviated by the concomitant depletion of Cdc25B or inhibition of CDK1. Since TIAR retains CDK1 in GMGs and attenuates CDK1 activity, we propose that the assembly of GMGs may represent a so far unrecognized mechanism that contributes to the activation of the G2/M checkpoint in mammalian cells.
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Affiliation(s)
- Vanesa Lafarga
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Hsu-Min Sung
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Division of Biochemistry, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Katharina Haneke
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Division of Biochemistry, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Lea Roessig
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Anne-Laure Pauleau
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Department of Cellular and Molecular Medicine, Center for Chromosome Stability and Center for Healthy Aging University of Copenhagen, Copenhagen, Denmark
| | - Marius Bruer
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Division of Biochemistry, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | | | - Andres J Lopez-Contreras
- Spanish National Cancer Research Centre (CNIO), Madrid, Spain
- CellNetworks Excellence Cluster, Heidelberg University, Heidelberg, Germany
| | - Oliver J Gruss
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Sylvia Erhardt
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Department of Cellular and Molecular Medicine, Center for Chromosome Stability and Center for Healthy Aging University of Copenhagen, Copenhagen, Denmark
| | - Juan Mendez
- Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Oscar Fernandez-Capetillo
- Spanish National Cancer Research Centre (CNIO), Madrid, Spain
- Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Georg Stoecklin
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Division of Biochemistry, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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15
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Schmidt M, Rohe A, Platzer C, Najjar A, Erdmann F, Sippl W. Regulation of G2/M Transition by Inhibition of WEE1 and PKMYT1 Kinases. Molecules 2017; 22:E2045. [PMID: 29168755 PMCID: PMC6149964 DOI: 10.3390/molecules22122045] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 11/21/2017] [Indexed: 01/04/2023] Open
Abstract
In the cell cycle, there are two checkpoint arrests that allow cells to repair damaged DNA in order to maintain genomic integrity. Many cancer cells have defective G1 checkpoint mechanisms, thus depending on the G2 checkpoint far more than normal cells. G2 checkpoint abrogation is therefore a promising concept to preferably damage cancerous cells over normal cells. The main factor influencing the decision to enter mitosis is a complex composed of Cdk1 and cyclin B. Cdk1/CycB is regulated by various feedback mechanisms, in particular inhibitory phosphorylations at Thr14 and Tyr15 of Cdk1. In fact, Cdk1/CycB activity is restricted by the balance between WEE family kinases and Cdc25 phosphatases. The WEE kinase family consists of three proteins: WEE1, PKMYT1, and the less important WEE1B. WEE1 exclusively mediates phosphorylation at Tyr15, whereas PKMYT1 is dual-specific for Tyr15 as well as Thr14. Inhibition by a small molecule inhibitor is therefore proposed to be a promising option since WEE kinases bind Cdk1, altering equilibria and thus affecting G2/M transition.
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Affiliation(s)
- Matthias Schmidt
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
| | - Alexander Rohe
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
| | - Charlott Platzer
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
| | - Abdulkarim Najjar
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
| | - Frank Erdmann
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
| | - Wolfgang Sippl
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
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16
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Zhu JY, Cuellar RA, Berndt N, Lee HE, Olesen SH, Martin MP, Jensen JT, Georg GI, Schönbrunn E. Structural Basis of Wee Kinases Functionality and Inactivation by Diverse Small Molecule Inhibitors. J Med Chem 2017; 60:7863-7875. [PMID: 28792760 PMCID: PMC6200136 DOI: 10.1021/acs.jmedchem.7b00996] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Members of the Wee family of kinases negatively regulate the cell cycle via phosphorylation of CDK1 and are considered potential drug targets. Herein, we investigated the structure-function relationship of human Wee1, Wee2, and Myt1 (PKMYT1). Purified recombinant full-length proteins and kinase domain constructs differed substantially in phosphorylation states and catalytic competency, suggesting complex mechanisms of activation. A series of crystal structures reveal unique features that distinguish Wee1 and Wee2 from Myt1 and establish the structural basis of differential inhibition by the widely used Wee1 inhibitor MK-1775. Kinome profiling and cellular studies demonstrate that, in addition to Wee1 and Wee2, MK-1775 is an equally potent inhibitor of the polo-like kinase PLK1. Several previously unrecognized inhibitors of Wee kinases were discovered and characterized. Combined, the data provide a comprehensive view on the catalytic and structural properties of Wee kinases and a framework for the rational design of novel inhibitors thereof.
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Affiliation(s)
- Jin-Yi Zhu
- Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida 33612, United States
| | - Rebecca A. Cuellar
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Norbert Berndt
- Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida 33612, United States
| | - Hee Eun Lee
- Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida 33612, United States
| | - Sanne H. Olesen
- Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida 33612, United States
| | - Mathew P. Martin
- Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida 33612, United States
| | - Jeffrey T. Jensen
- Division of Reproductive and Developmental Science, Oregon National Primate Research Center, Beaverton, Oregon 97006, United States
| | - Gunda I. Georg
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Ernst Schönbrunn
- Drug Discovery Department, Moffitt Cancer Center, Tampa, Florida 33612, United States
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17
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Ayala I, Colanzi A. Mitotic inheritance of the Golgi complex and its role in cell division. Biol Cell 2017; 109:364-374. [PMID: 28799169 DOI: 10.1111/boc.201700032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/04/2017] [Accepted: 08/04/2017] [Indexed: 12/30/2022]
Abstract
The Golgi apparatus plays essential roles in the processing and sorting of proteins and lipids, but it can also act as a signalling hub and a microtubule-nucleation centre. The Golgi complex (GC) of mammalian cells is composed of stacks connected by tubular bridges to form a continuous membranous system. In spite of this structural complexity, the GC is highly dynamic, and this feature becomes particularly evident during mitosis, when the GC undergoes a multi-step disassembly process that allows its correct partitioning and inheritance by daughter cells. Strikingly, different steps of Golgi disassembly control mitotic entry and progression, indicating that cells actively monitor Golgi integrity during cell division. Here, we summarise the basic mechanisms and the molecular players that are involved in Golgi disassembly, focussing in particular on recent studies that have revealed the fundamental signalling pathways that connect Golgi inheritance to mitotic entry and progression.
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Affiliation(s)
- Inmaculada Ayala
- Institute of Protein Biochemistry, National Research Council, Naples, 80131, Italy
| | - Antonino Colanzi
- Institute of Protein Biochemistry, National Research Council, Naples, 80131, Italy
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18
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Guerrero PA, Tchaicha JH, Chen Z, Morales JE, McCarty N, Wang Q, Sulman EP, Fuller G, Lang FF, Rao G, McCarty JH. Glioblastoma stem cells exploit the αvβ8 integrin-TGFβ1 signaling axis to drive tumor initiation and progression. Oncogene 2017; 36:6568-6580. [PMID: 28783169 DOI: 10.1038/onc.2017.248] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/16/2017] [Accepted: 06/19/2017] [Indexed: 12/13/2022]
Abstract
Glioblastoma (GBM) is a primary brain cancer that contains populations of stem-like cancer cells (GSCs) that home to specialized perivascular niches. GSC interactions with their niche influence self-renewal, differentiation and drug resistance, although the pathways underlying these events remain largely unknown. Here, we report that the integrin αvβ8 and its latent transforming growth factor β1 (TGFβ1) protein ligand have central roles in promoting niche co-option and GBM initiation. αvβ8 integrin is highly expressed in GSCs and is essential for self-renewal and lineage commitment in vitro. Fractionation of β8high cells from freshly resected human GBM samples also reveals a requirement for this integrin in tumorigenesis in vivo. Whole-transcriptome sequencing reveals that αvβ8 integrin regulates tumor development, in part, by driving TGFβ1-induced DNA replication and mitotic checkpoint progression. Collectively, these data identify the αvβ8 integrin-TGFβ1 signaling axis as crucial for exploitation of the perivascular niche and identify potential therapeutic targets for inhibiting tumor growth and progression in patients with GBM.
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Affiliation(s)
- P A Guerrero
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
| | - J H Tchaicha
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
| | - Z Chen
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
| | - J E Morales
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
| | - N McCarty
- The Brown Institute for Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Q Wang
- Department of Radiation Oncology, M. D. Anderson Cancer Center, Houston, TX, USA.,Department of Genomic Medicine, M. D. Anderson Cancer Center, Houston, TX, USA
| | - E P Sulman
- Department of Radiation Oncology, M. D. Anderson Cancer Center, Houston, TX, USA.,Department of Genomic Medicine, M. D. Anderson Cancer Center, Houston, TX, USA.,Department of Translational Molecular Pathology, M. D. Anderson Cancer Center, Houston, TX, USA
| | - G Fuller
- Departments of Pathology, M. D. Anderson Cancer Center, Houston, TX, USA
| | - F F Lang
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
| | - G Rao
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
| | - J H McCarty
- Department of Neurosurgery, M. D. Anderson Cancer Center, Houston, TX, USA
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19
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Lewis CW, Jin Z, Macdonald D, Wei W, Qian XJ, Choi WS, He R, Sun X, Chan G. Prolonged mitotic arrest induced by Wee1 inhibition sensitizes breast cancer cells to paclitaxel. Oncotarget 2017; 8:73705-73722. [PMID: 29088738 PMCID: PMC5650293 DOI: 10.18632/oncotarget.17848] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 04/27/2017] [Indexed: 11/25/2022] Open
Abstract
Wee1 kinase is a crucial negative regulator of Cdk1/cyclin B1 activity and is required for normal entry into and exit from mitosis. Wee1 activity can be chemically inhibited by the small molecule MK-1775, which is currently being tested in phase I/II clinical trials in combination with other anti-cancer drugs. MK-1775 promotes cancer cells to bypass the cell-cycle checkpoints and prematurely enter mitosis. In our study, we show premature mitotic cells that arise from MK-1775 treatment exhibited centromere fragmentation, a morphological feature of mitotic catastrophe that is characterized by centromeres and kinetochore proteins that co-cluster away from the condensed chromosomes. In addition to stimulating early mitotic entry, MK-1775 treatment also delayed mitotic exit. Specifically, cells treated with MK-1775 following release from G1/S or prometaphase arrested in mitosis. MK-1775 induced arrest occurred at metaphase and thus, cells required 12 times longer to transition into anaphase compared to controls. Consistent with an arrest in mitosis, MK-1775 treated prometaphase cells maintained high cyclin B1 and low phospho-tyrosine 15 Cdk1. Importantly, MK-1775 induced mitotic arrest resulted in cell death regardless the of cell-cycle phase prior to treatment suggesting that Wee1 inhibitors are also anti-mitotic agents. We found that paclitaxel enhances MK-1775 mediated cell killing. HeLa and different breast cancer cell lines (T-47D, MCF7, MDA-MB-468 and MDA-MB-231) treated with different concentrations of MK-1775 and low dose paclitaxel exhibited reduced cell survival compared to mono-treatments. Our data highlight a new potential strategy for enhancing MK-1775 mediated cell killing in breast cancer cells.
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Affiliation(s)
- Cody W Lewis
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada T6G 1Z2.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada T6G 2J7
| | - Zhigang Jin
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada T6G 1Z2.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada T6G 2J7
| | - Dawn Macdonald
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada T6G 1Z2.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada T6G 2J7
| | - Wenya Wei
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2
| | - Xu Jing Qian
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2
| | - Won Shik Choi
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2
| | - Ruicen He
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2
| | - Xuejun Sun
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada T6G 1Z2.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada T6G 2J7
| | - Gordon Chan
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 1Z2.,Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada T6G 1Z2.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada T6G 2J7
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20
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Sanchez-Alvarez M, Zhang Q, Finger F, Wakelam MJO, Bakal C. Cell cycle progression is an essential regulatory component of phospholipid metabolism and membrane homeostasis. Open Biol 2016; 5:150093. [PMID: 26333836 PMCID: PMC4593667 DOI: 10.1098/rsob.150093] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We show that phospholipid anabolism does not occur uniformly during the metazoan cell cycle. Transition to S-phase is required for optimal mobilization of lipid precursors, synthesis of specific phospholipid species and endoplasmic reticulum (ER) homeostasis. Average changes observed in whole-cell phospholipid composition, and total ER lipid content, upon stimulation of cell growth can be explained by the cell cycle distribution of the population. TORC1 promotes phospholipid anabolism by slowing S/G2 progression. The cell cycle stage-specific nature of lipid biogenesis is dependent on p53. We propose that coupling lipid metabolism to cell cycle progression is a means by which cells have evolved to coordinate proliferation with cell and organelle growth.
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Affiliation(s)
- Miguel Sanchez-Alvarez
- Division of Cancer Biology, Chester Beatty Laboratories, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Qifeng Zhang
- Lipidomics Facility, Babraham Institute, Cambridge CB22 3AT, UK
| | - Fabian Finger
- Division of Cancer Biology, Chester Beatty Laboratories, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | | | - Chris Bakal
- Division of Cancer Biology, Chester Beatty Laboratories, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
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21
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Varadarajan R, Ayeni J, Jin Z, Homola E, Campbell SD. Myt1 inhibition of Cyclin A/Cdk1 is essential for fusome integrity and premeiotic centriole engagement in Drosophila spermatocytes. Mol Biol Cell 2016; 27:2051-63. [PMID: 27170181 PMCID: PMC4927279 DOI: 10.1091/mbc.e16-02-0104] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/05/2016] [Indexed: 12/14/2022] Open
Abstract
Drosophila Myt1 is essential for male fertility. Loss of Myt1 activity causes defective fusomes and premature centriole disengagement during premeiotic G2 phase due to lack of Myt1 inhibition of Cyclin A/Cdk1. These functions are distinct from known roles for Myt1 inhibition of Cyclin B/Cdk1 used to regulate G2/MI timing. Regulation of cell cycle arrest in premeiotic G2 phase coordinates germ cell maturation and meiotic cell division with hormonal and developmental signals by mechanisms that control Cyclin B synthesis and inhibitory phosphorylation of the M-phase kinase, Cdk1. In this study, we investigated how inhibitory phosphorylation of Cdk1 by Myt1 kinase regulates premeiotic G2 phase of Drosophila male meiosis. Immature spermatocytes lacking Myt1 activity exhibit two distinct defects: disrupted intercellular bridges (fusomes) and premature centriole disengagement. As a result, the myt1 mutant spermatocytes enter meiosis with multipolar spindles. These myt1 defects can be suppressed by depletion of Cyclin A activity or ectopic expression of Wee1 (a partially redundant Cdk1 inhibitory kinase) and phenocopied by expression of a Cdk1F mutant defective for inhibitory phosphorylation. We therefore conclude that Myt1 inhibition of Cyclin A/Cdk1 is essential for normal fusome behavior and centriole engagement during premeiotic G2 arrest of Drosophila male meiosis. The novel meiotic functions we discovered for Myt1 kinase are spatially and temporally distinct from previously described functions of Myt1 as an inhibitor of Cyclin B/Cdk1 to regulate G2/MI timing.
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Affiliation(s)
- Ramya Varadarajan
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Joseph Ayeni
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Zhigang Jin
- Cross Cancer Institute, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Ellen Homola
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Shelagh D Campbell
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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22
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Toledo CM, Ding Y, Hoellerbauer P, Davis RJ, Basom R, Girard EJ, Lee E, Corrin P, Hart T, Bolouri H, Davison J, Zhang Q, Hardcastle J, Aronow BJ, Plaisier CL, Baliga NS, Moffat J, Lin Q, Li XN, Nam DH, Lee J, Pollard SM, Zhu J, Delrow JJ, Clurman BE, Olson JM, Paddison PJ. Genome-wide CRISPR-Cas9 Screens Reveal Loss of Redundancy between PKMYT1 and WEE1 in Glioblastoma Stem-like Cells. Cell Rep 2015; 13:2425-2439. [PMID: 26673326 PMCID: PMC4691575 DOI: 10.1016/j.celrep.2015.11.021] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/12/2015] [Accepted: 11/03/2015] [Indexed: 12/31/2022] Open
Abstract
To identify therapeutic targets for glioblastoma (GBM), we performed genome-wide CRISPR-Cas9 knockout (KO) screens in patient-derived GBM stem-like cells (GSCs) and human neural stem/progenitors (NSCs), non-neoplastic stem cell controls, for genes required for their in vitro growth. Surprisingly, the vast majority GSC-lethal hits were found outside of molecular networks commonly altered in GBM and GSCs (e.g., oncogenic drivers). In vitro and in vivo validation of GSC-specific targets revealed several strong hits, including the wee1-like kinase, PKMYT1/Myt1. Mechanistic studies demonstrated that PKMYT1 acts redundantly with WEE1 to inhibit cyclin B-CDK1 activity via CDK1-Y15 phosphorylation and to promote timely completion of mitosis in NSCs. However, in GSCs, this redundancy is lost, most likely as a result of oncogenic signaling, causing GBM-specific lethality.
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Affiliation(s)
- Chad M Toledo
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Yu Ding
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Pia Hoellerbauer
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Ryan J Davis
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA; Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Ryan Basom
- Genomics and Bioinformatics Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Emily J Girard
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Eunjee Lee
- Department of Genetics and Genomic Sciences, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Philip Corrin
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Traver Hart
- Department of Molecular Genetics, University of Toronto and Donnelly Centre, Toronto, ON M5S3E1, Canada; Canadian Institute for Advanced Research, Toronto, ON M5G1Z8, Canada
| | - Hamid Bolouri
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Jerry Davison
- Genomics and Bioinformatics Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Qing Zhang
- Genomics and Bioinformatics Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Justin Hardcastle
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Bruce J Aronow
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | | | | | - Jason Moffat
- Department of Molecular Genetics, University of Toronto and Donnelly Centre, Toronto, ON M5S3E1, Canada; Canadian Institute for Advanced Research, Toronto, ON M5G1Z8, Canada
| | - Qi Lin
- Brain Tumor Program, Texas Children's Cancer Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xiao-Nan Li
- Brain Tumor Program, Texas Children's Cancer Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Do-Hyun Nam
- Institute for Refractory Cancer Research, Samsung Medical Center, Seoul 135-710, Korea
| | - Jeongwu Lee
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44192, USA
| | - Steven M Pollard
- Edinburgh CRUK Cancer Research Centre and MRC Centre for Regenerative Medicine, The University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Jun Zhu
- Department of Genetics and Genomic Sciences, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jeffery J Delrow
- Genomics and Bioinformatics Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Bruce E Clurman
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - James M Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | - Patrick J Paddison
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA.
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23
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Valente C, Colanzi A. Mechanisms and Regulation of the Mitotic Inheritance of the Golgi Complex. Front Cell Dev Biol 2015; 3:79. [PMID: 26734607 PMCID: PMC4679863 DOI: 10.3389/fcell.2015.00079] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/27/2015] [Indexed: 11/13/2022] Open
Abstract
In mammalian cells, the Golgi complex is structured in the form of a continuous membranous system composed of stacks connected by tubular bridges: the "Golgi ribbon." At the onset of mitosis, the Golgi complex undergoes a multi-step fragmentation process that is required for its correct partition into the dividing cells. Importantly, inhibition of Golgi disassembly results in cell-cycle arrest at the G2 stage, which indicates that accurate inheritance of the Golgi complex is monitored by a "Golgi mitotic checkpoint." Moreover, mitotic Golgi disassembly correlates with the release of a set of Golgi-localized proteins that acquire specific functions during mitosis, such as mitotic spindle formation and regulation of the spindle checkpoint. Most of these events are regulated by small GTPases of the Arf and Rab families. Here, we review recent studies that are revealing the fundamental mechanisms, the molecular players, and the biological significance of mitotic inheritance of the Golgi complex in mammalian cells. We also briefly comment on how Golgi partitioning is coordinated with mitotic progression.
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Affiliation(s)
- Carmen Valente
- Institute of Protein Biochemistry, National Research Council Naples, Italy
| | - Antonino Colanzi
- Institute of Protein Biochemistry, National Research Council Naples, Italy
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24
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Bergman ZJ, Mclaurin JD, Eritano AS, Johnson BM, Sims AQ, Riggs B. Spatial reorganization of the endoplasmic reticulum during mitosis relies on mitotic kinase cyclin A in the early Drosophila embryo. PLoS One 2015; 10:e0117859. [PMID: 25689737 PMCID: PMC4331435 DOI: 10.1371/journal.pone.0117859] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 12/24/2014] [Indexed: 11/19/2022] Open
Abstract
Mitotic cyclin-dependent kinase with their cyclin partners (cyclin:Cdks) are the master regulators of cell cycle progression responsible for regulating a host of activities during mitosis. Nuclear mitotic events, including chromosome condensation and segregation have been directly linked to Cdk activity. However, the regulation and timing of cytoplasmic mitotic events by cyclin:Cdks is poorly understood. In order to examine these mitotic cytoplasmic events, we looked at the dramatic changes in the endoplasmic reticulum (ER) during mitosis in the early Drosophila embryo. The dynamic changes of the ER can be arrested in an interphase state by inhibition of either DNA or protein synthesis. Here we show that this block can be alleviated by micro-injection of Cyclin A (CycA) in which defined mitotic ER clusters gathered at the spindle poles. Conversely, micro-injection of Cyclin B (CycB) did not affect spatial reorganization of the ER, suggesting CycA possesses the ability to initiate mitotic ER events in the cytoplasm. Additionally, RNAi-mediated simultaneous inhibition of all 3 mitotic cyclins (A, B and B3) blocked spatial reorganization of the ER. Our results suggest that mitotic ER reorganization events rely on CycA and that control and timing of nuclear and cytoplasmic events during mitosis may be defined by release of CycA from the nucleus as a consequence of breakdown of the nuclear envelope.
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Affiliation(s)
- Zane J. Bergman
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, California, 94132, United States of America
| | - Justin D. Mclaurin
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, California, 94132, United States of America
| | - Anthony S. Eritano
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, California, 94132, United States of America
| | - Brittany M. Johnson
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, California, 94132, United States of America
| | - Amanda Q. Sims
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, California, 94132, United States of America
| | - Blake Riggs
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, California, 94132, United States of America
- * E-mail:
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25
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Chia J, Tham KM, Gill DJ, Bard-Chapeau EA, Bard FA. ERK8 is a negative regulator of O-GalNAc glycosylation and cell migration. eLife 2014; 3:e01828. [PMID: 24618899 PMCID: PMC3945522 DOI: 10.7554/elife.01828] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
ER O-glycosylation can be induced through relocalisation GalNAc-Transferases from the Golgi. This process markedly stimulates cell migration and is constitutively activated in more than 60% of breast carcinomas. How this activation is achieved remains unclear. Here, we screened 948 signalling genes using RNAi and imaging. We identified 12 negative regulators of O-glycosylation that all control GalNAc-T sub-cellular localisation. ERK8, an atypical MAPK with high basal kinase activity, is a strong hit and is partially localised at the Golgi. Its inhibition induces the relocation of GalNAc-Ts, but not of KDEL receptors, revealing the existence of two separate COPI-dependent pathways. ERK8 down-regulation, in turn, activates cell motility. In human breast and lung carcinomas, ERK8 expression is reduced while ER O-glycosylation initiation is hyperactivated. In sum, ERK8 appears as a constitutive brake on GalNAc-T relocalisation, and the loss of its expression could drive cancer aggressivity through increased cell motility. DOI:http://dx.doi.org/10.7554/eLife.01828.001 The likelihood of an individual being able to recover from cancer depends on: where the cancer is within the body, how quickly the disease is detected and how quickly treatment is started. Cancers that have spread from their original location to another part of the body are particular challenging to treat, and cause the vast majority of cancer deaths every year. Treatments that can recognize and eradicate cancer cells, while leaving nearby healthy cells untouched, are still needed—and so there has been a lot of research into identifying the key differences between healthy cells and cancer cells. For several decades, researchers have been aware that cancer cells have more proteins coated with modified sugars on their cell surfaces than healthy cells. This is caused by the enzymes that add these sugars to the proteins relocating from one location within the cell, the Golgi apparatus, to another, called the endoplasmic reticulum. These specific ‘sugar-coated’ proteins are known to encourage cancer cells to migrate and invade new tissues, but the mechanisms that regulate the addition of these sugar molecules to proteins remains poorly understood. Now Chia et al. have discovered 12 molecules that regulate this process, including an enzyme called ERK8 that is found at the Golgi apparatus. ERK8 is shown to prevent the relocation of the sugar-adding enzymes from the Golgi to the endoplasmic reticulum, thereby restricting the production of sugar-coated proteins that help the cancer cells to spread within the body. By identifying 12 potential targets for new therapeutics aimed at preventing the spread of cancer, the work of Chia et al. could ultimately help to improve the chances of patients recovering from certain cancers. DOI:http://dx.doi.org/10.7554/eLife.01828.002
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Affiliation(s)
- Joanne Chia
- Institute of Molecular and Cell Biology, Singapore, Singapore
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26
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Abstract
The Ras-Raf-MEK-ERK signaling cascade is capable of channeling a wide variety of extracellular signals into control of cell proliferation, differentiation, senescence, and death. Because aberrant regulation at all steps of this signaling axis is observed in cancer, it remains an area of great interest in the field of tumor biology. Here we present evidence of the intricate and delicate levels of control of this pathway as it pertains to cell cycle regulation and illustrate how this control is not simply a rheostat.
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Affiliation(s)
- Paul M Campbell
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, MS 488, Philadelphia, PA, 19102, USA,
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27
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Dual phosphorylation of cdk1 coordinates cell proliferation with key developmental processes in Drosophila. Genetics 2013; 196:197-210. [PMID: 24214341 DOI: 10.1534/genetics.113.156281] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Eukaryotic organisms use conserved checkpoint mechanisms that regulate Cdk1 by inhibitory phosphorylation to prevent mitosis from interfering with DNA replication or repair. In metazoans, this checkpoint mechanism is also used for coordinating mitosis with dynamic developmental processes. Inhibitory phosphorylation of Cdk1 is catalyzed by Wee1 kinases that phosphorylate tyrosine 15 (Y15) and dual-specificity Myt1 kinases found only in metazoans that phosphorylate Y15 and the adjacent threonine (T14) residue. Despite partially redundant roles in Cdk1 inhibitory phosphorylation, Wee1 and Myt1 serve specialized developmental functions that are not well understood. Here, we expressed wild-type and phospho-acceptor mutant Cdk1 proteins to investigate how biochemical differences in Cdk1 inhibitory phosphorylation influence Drosophila imaginal development. Phosphorylation of Cdk1 on Y15 appeared to be crucial for developmental and DNA damage-induced G2-phase checkpoint arrest, consistent with other evidence that Myt1 is the major Y15-directed Cdk1 inhibitory kinase at this stage of development. Expression of non-inhibitable Cdk1 also caused chromosome defects in larval neuroblasts that were not observed with Cdk1(Y15F) mutant proteins that were phosphorylated on T14, implicating Myt1 in a novel mechanism promoting genome stability. Collectively, these results suggest that dual inhibitory phosphorylation of Cdk1 by Myt1 serves at least two functions during development. Phosphorylation of Y15 is essential for the premitotic checkpoint mechanism, whereas T14 phosphorylation facilitates accumulation of dually inhibited Cdk1-Cyclin B complexes that can be rapidly activated once checkpoint-arrested G2-phase cells are ready for mitosis.
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28
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Ser 15 of WEE1B is a potential PKA phosphorylation target in G2/M transition in one-cell stage mouse embryos. Mol Med Rep 2013; 7:1929-37. [DOI: 10.3892/mmr.2013.1437] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 03/28/2013] [Indexed: 11/05/2022] Open
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29
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Yeong FM. Multi-step down-regulation of the secretory pathway in mitosis: a fresh perspective on protein trafficking. Bioessays 2013; 35:462-71. [PMID: 23494566 PMCID: PMC3654163 DOI: 10.1002/bies.201200144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The secretory pathway delivers proteins synthesized at the rough endoplasmic reticulum (RER) to various subcellular locations via the Golgi apparatus. Currently, efforts are focused on understanding the molecular machineries driving individual processes at the RER and Golgi that package, modify and transport proteins. However, studies are routinely performed using non-dividing cells. This obscures the critical issue of how the secretory pathway is affected by cell division. Indeed, several studies have indicated that protein trafficking is down-regulated during mitosis. Moreover, the RER and Golgi apparatus exhibit gross reorganization in mitosis. Here I provide a relatively neglected perspective of how the mitotic cyclin-dependent kinase (CDK1) could regulate various stages of the secretory pathway. I highlight several aspects of the mitotic control of protein trafficking that remain unresolved and suggest that further studies on how the mitotic CDK1 influences the secretory pathway are necessary to obtain a deeper understanding of protein transport.
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Affiliation(s)
- Foong May Yeong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
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30
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Abstract
The Golgi complex of mammalian cells is composed of interconnected stacks of flattened cisternae that form a continuous membrane system in the pericentriolar region of the cell. At the onset of mitosis, this so-called Golgi ribbon is converted into small tubular-vesicular clusters in a tightly regulated fragmentation process, which leads to a temporary loss of the physical Golgi-centrosome proximity. Mitotic Golgi breakdown is required for Golgi partitioning into the two daughter cells, cell cycle progression and may contribute to the dispersal of Golgi-associated signaling molecules. Here, we review our current understanding of the mechanisms that control mitotic Golgi reorganization, its biological significance, and assays that are used to study this process.
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31
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MEK1 inactivates Myt1 to regulate Golgi membrane fragmentation and mitotic entry in mammalian cells. EMBO J 2012; 32:72-85. [PMID: 23241949 DOI: 10.1038/emboj.2012.329] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 11/16/2012] [Indexed: 11/08/2022] Open
Abstract
The pericentriolar stacks of Golgi cisternae are separated from each other in G2 and fragmented extensively during mitosis. MEK1 is required for Golgi fragmentation in G2 and for the entry of cells into mitosis. We now report that Myt1 mediates MEK1's effects on the Golgi complex. Knockdown of Myt1 by siRNA increased the efficiency of Golgi complex fragmentation by mitotic cytosol in permeabilized and intact HeLa cells. Myt1 knockdown eliminated the requirement of MEK1 in Golgi fragmentation and alleviated the delay in mitotic entry due to MEK1 inhibition. The phosphorylation of Myt1 by MEK1 requires another kinase but is independent of RSK, Plk, and CDK1. Altogether our findings reveal that Myt1 is inactivated by MEK1 mediated phosphorylation to fragment the Golgi complex in G2 and for the entry of cells into mitosis. It is known that Myt1 inactivation is required for CDK1 activation. Myt1 therefore is an important link by which MEK1 dependent fragmentation of the Golgi complex in G2 is connected to the CDK1 mediated breakdown of Golgi into tubules and vesicles in mitosis.
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32
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Chow JPH, Poon RYC. The CDK1 inhibitory kinase MYT1 in DNA damage checkpoint recovery. Oncogene 2012; 32:4778-88. [PMID: 23146904 DOI: 10.1038/onc.2012.504] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 09/14/2012] [Accepted: 09/18/2012] [Indexed: 02/07/2023]
Abstract
Inhibition of cyclin-dependent kinase 1 (CDK1) by phosphorylation is a key regulatory mechanism for both the unperturbed cell cycle and the DNA damage checkpoint. Although both WEE1 and MYT1 can phosphorylate CDK1, little is known about the contribution of MYT1. We found that in contrast to WEE1, MYT1 was not important for the normal cell cycle or checkpoint activation. Time-lapse microscopy indicated that MYT1 did, however, have a rate-determining role during checkpoint recovery. Depletion of MYT1 induced precocious mitotic entry when the checkpoint was abrogated with inhibitors of either CHK1 or WEE1, indicating that MYT1 contributes to checkpoint recovery independently of WEE1. The acceleration of checkpoint recovery in MYT1-depleted cells was due to a lowering of threshold for CDK1 activation. The kinase activity of MYT1 was high during checkpoint activation and reduced during checkpoint recovery. Importantly, although depletion of MYT1 alone did not affect long-term cell growth, it potentiated with DNA damage to inhibit cell growth in clonogenic survival and tumor xenograft models. These results reveal the functions of MYT1 in checkpoint recovery and highlight the potential of MYT1 as a target for anti-cancer therapies.
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Affiliation(s)
- J P H Chow
- Division of Life Science and Center for Cancer Research, Hong Kong University of Science and Technology, Kowloon, Hong Kong
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33
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Yoshitome S, Furuno N, Prigent C, Hashimoto E. The subcellular localization of cyclin B2 is required for bipolar spindle formation during Xenopus oocyte maturation. Biochem Biophys Res Commun 2012; 422:770-5. [PMID: 22627133 DOI: 10.1016/j.bbrc.2012.05.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 05/13/2012] [Indexed: 11/30/2022]
Abstract
Cyclins B1 and B2 are subtypes of cyclin B, a regulatory subunit of a maturation/M-phase promoting factor, and they are also highly conserved in many vertebrate species. Cyclin B1 is essential for mitosis, whereas cyclin B2 is regarded as dispensable. However, the overexpression of the cyclin B2 N-terminus containing the cytoplasmic retention signal, but not cyclin B1, inhibits bipolar spindle formation in Xenopus oocytes and embryos. Here we show that endogenous cyclin B2 was localized in and around the germinal vesicle. The perinuclear localization of cyclin B2 was perturbed by the overexpression of its N-terminus containing the cytoplasmic retention signal, which resulted in a spindle defect. This spindle defect was rescued by the overexpression of bipolar kinesin Eg5, which is located at the perinuclear region in the proximity of endogenous cyclin B2. These results demonstrate that the proper localization of cyclin B2 is essential for bipolar spindle formation in Xenopus oocytes.
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Affiliation(s)
- Satoshi Yoshitome
- Faculty of Pharmacy, Iwaki Meisei University, Iwaki 970-8551, Japan.
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34
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Coulonval K, Kooken H, Roger PP. Coupling of T161 and T14 phosphorylations protects cyclin B-CDK1 from premature activation. Mol Biol Cell 2011; 22:3971-85. [PMID: 21900495 PMCID: PMC3204060 DOI: 10.1091/mbc.e11-02-0136] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 08/19/2011] [Accepted: 09/01/2011] [Indexed: 01/26/2023] Open
Abstract
Mitosis is triggered by the abrupt dephosphorylation of inhibitory Y15 and T14 residues of cyclin B1-bound cyclin-dependent kinase (CDK)1 that is also phosphorylated at T161 in its activation loop. The sequence of events leading to the accumulation of fully phosphorylated cyclin B1-CDK1 complexes remains unclear. Two-dimensional gel electrophoresis allowed us to determine whether T14, Y15, and T161 phosphorylations occur on same CDK1 molecules and to characterize the physiological occurrence of their seven phosphorylation combinations. Intriguingly, in cyclin B1-CDK1, the activating T161 phosphorylation never occurred without the T14 phosphorylation. This strict association could not be uncoupled by a substantial reduction of T14 phosphorylation in response to Myt1 knockdown, suggesting some causal relationship. However, T14 phosphorylation was not directly required for T161 phosphorylation, because Myt1 knockdown did uncouple these phosphorylations when leptomycin B prevented cyclin B1-CDK1 complexes from accumulating in cytoplasm. The coupling mechanism therefore depended on unperturbed cyclin B1-CDK1 traffic. The unexpected observation that the activating phosphorylation of cyclin B1-CDK1 was tightly coupled to its T14 phosphorylation, but not Y15 phosphorylation, suggests a mechanism that prevents premature activation by constitutively active CDK-activating kinase. This explained the opposite effects of reduced expression of Myt1 and Wee1, with only the latter inducing catastrophic mitoses.
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Affiliation(s)
- Katia Coulonval
- Institute of Interdisciplinary Research (IRIBHM), Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
| | - Hugues Kooken
- Institute of Interdisciplinary Research (IRIBHM), Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
| | - Pierre P. Roger
- Institute of Interdisciplinary Research (IRIBHM), Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
- WELBIO
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35
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Tran T, Kolupaeva V, Basilico C. FGF inhibits the activity of the cyclin B1/CDK1 kinase to induce a transient G₂arrest in RCS chondrocytes. Cell Cycle 2010; 9:4379-86. [PMID: 21051949 DOI: 10.4161/cc.9.21.13671] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Fibroblast growth factors (FGFs) negatively regulate long bone development by inhibiting the proliferation of chondrocytes that accumulate in the G₁ phase of the cycle following FGF treatment. Here we report that FGF also causes a striking but transient delay in mitotic entry in RCS chondrocytes by inactivating the cyclin B1-associated CDK1(CDC2) kinase. As a consequence of this inactivation, cells accumulate in the G₂ phase of the cycle for the first 4-6 hours of the treatment. Cyclin B1/CDK1 activity is then restored and cells reach a G₁ arrest. The reduced cyclin B1/CDK1 activity was accompanied by increased CDK1 inhibitory phosphorylation, likely caused by increased activity and expression of the Myt1 kinase. FGF1 also caused dephosphorylation of the CDC25C phosphatase, that however appears due the inactivation of cyclin B1/CDK1 complex in the CDK1 feedback loop, and not the activation of specific phosphatases. the inactivation of the cyclin B1/CDK1 complex is a direct effect of FGF signaling, and not a consequence of the G₂ arrest as it can be observed also in cells blocked at mitosis by Nocodazole. The Chk1 and AtM/ATR kinase are known to play essential roles in the G₂ checkpoint induced by DNA damage/genotoxic stress, but inhibition of Chk1 or ATM/ATR not only did not prevent, but rather potentiated the FGF-induced G₂ arrest. Additionally our results indicate that the transient G₂ arrest is induced by FGF in RCS cell through mechanisms that are independent of the G₁ arrest, and that the G₂ block is not strictly required for the sustained G₁ arrest but may provide a pausing mechanism that allows the FGF response to be fully established.
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Affiliation(s)
- Tri Tran
- NYU School of Medicine, New York, USA
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36
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Persico A, Cervigni RI, Barretta ML, Corda D, Colanzi A. Golgi partitioning controls mitotic entry through Aurora-A kinase. Mol Biol Cell 2010; 21:3708-21. [PMID: 20844084 PMCID: PMC2965687 DOI: 10.1091/mbc.e10-03-0243] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
At the onset of mitosis, the Golgi complex undergoes a multistep fragmentation process that is required for its correct partitioning into the daughter cells. Inhibition of this Golgi fragmentation results in cell cycle arrest at the G2 stage, suggesting that correct inheritance of the Golgi complex is monitored by a "Golgi mitotic checkpoint." However, the molecular basis of this G2 block is not known. Here, we show that the G2-specific Golgi fragmentation stage is concomitant with centrosome recruitment and activation of the mitotic kinase Aurora-A, an essential regulator for entry into mitosis. We show that a block of Golgi partitioning impairs centrosome recruitment and activation of Aurora-A, which results in the G2 block of cell cycle progression. Overexpression of Aurora-A overrides this cell cycle block, indicating that Aurora-A is a major effector of the Golgi checkpoint. Our findings provide the basis for further understanding of the signaling pathways that coordinate organelle inheritance and cell duplication.
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Affiliation(s)
- Angela Persico
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro, Chieti, Italy
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37
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Wei JH, Seemann J. Mitotic division of the mammalian Golgi apparatus. Semin Cell Dev Biol 2009; 20:810-6. [PMID: 19508856 DOI: 10.1016/j.semcdb.2009.03.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 03/16/2009] [Accepted: 03/16/2009] [Indexed: 10/21/2022]
Abstract
Successful cell reproduction requires faithful duplication and proper segregation of cellular contents, including not only the genome but also intracellular organelles. Since the Golgi apparatus is an essential organelle of the secretory pathway, its accurate inheritance is therefore of importance to sustain cellular function. Regulation of Golgi division and its coordination with cell cycle progression involves a series of sequential events that are subjected to a precise spatiotemporal control. Here, we summarize the current knowledge about the underlying mechanisms, the molecular players and the biological relevance of this process, particularly in mammalian cells, and discuss the unsolved problems and future perspectives opened by the recent studies.
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Affiliation(s)
- Jen-Hsuan Wei
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Lindqvist A, Rodríguez-Bravo V, Medema RH. The decision to enter mitosis: feedback and redundancy in the mitotic entry network. ACTA ACUST UNITED AC 2009; 185:193-202. [PMID: 19364923 PMCID: PMC2700378 DOI: 10.1083/jcb.200812045] [Citation(s) in RCA: 410] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The decision to enter mitosis is mediated by a network of proteins that regulate activation of the cyclin B–Cdk1 complex. Within this network, several positive feedback loops can amplify cyclin B–Cdk1 activation to ensure complete commitment to a mitotic state once the decision to enter mitosis has been made. However, evidence is accumulating that several components of the feedback loops are redundant for cyclin B–Cdk1 activation during normal cell division. Nonetheless, defined feedback loops become essential to promote mitotic entry when normal cell cycle progression is perturbed. Recent data has demonstrated that at least three Plk1-dependent feedback loops exist that enhance cyclin B–Cdk1 activation at different levels. In this review, we discuss the role of various feedback loops that regulate cyclin B–Cdk1 activation under different conditions, the timing of their activation, and the possible identity of the elusive trigger that controls mitotic entry in human cells.
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Affiliation(s)
- Arne Lindqvist
- Department of Medical Oncology, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands
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Potapova TA, Daum JR, Byrd KS, Gorbsky GJ. Fine tuning the cell cycle: activation of the Cdk1 inhibitory phosphorylation pathway during mitotic exit. Mol Biol Cell 2009; 20:1737-48. [PMID: 19158392 DOI: 10.1091/mbc.e08-07-0771] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inactivation of cyclin-dependent kinase (Cdk) 1 promotes exit from mitosis and establishes G1. Proteolysis of cyclin B is the major known mechanism that turns off Cdk1 during mitotic exit. Here, we show that mitotic exit also activates pathways that catalyze inhibitory phosphorylation of Cdk1, a mechanism previously known to repress Cdk1 only during S and G2 phases of the cell cycle. We present evidence that down-regulation of Cdk1 activates Wee1 and Myt1 kinases and inhibits Cdc25 phosphatase during the M to G1 transition. If cyclin B/Cdk1 complex is present in G1, the inhibitory sites on Cdk1 become phosphorylated. Exit from mitosis induced by chemical Cdk inhibition can be reversed if cyclin B is preserved. However, this reversibility decreases with time after mitotic exit despite the continued presence of the cyclin. We show that this G1 block is due to phosphorylation of Cdk1 on inhibitory residues T14 and Y15. Chemical inhibition of Wee1 and Myt1 or expression of Cdk1 phosphorylation site mutants allows reversal to M phase even from late G1. This late Cdk1 reactivation often results in caspase-dependent cell death. Thus, in G1, the Cdk inhibitory phosphorylation pathway is functional and can lock Cdk1 in the inactive state.
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Affiliation(s)
- Tamara A Potapova
- Cell Cycle and Cancer Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Drosophila myt1 is the major cdk1 inhibitory kinase for wing imaginal disc development. Genetics 2008; 180:2123-33. [PMID: 18940789 DOI: 10.1534/genetics.108.093195] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mitosis is triggered by activation of Cdk1, a cyclin-dependent kinase. Conserved checkpoint mechanisms normally inhibit Cdk1 by inhibitory phosphorylation during interphase, ensuring that DNA replication and repair is completed before cells begin mitosis. In metazoans, this regulatory mechanism is also used to coordinate cell division with critical developmental processes, such as cell invagination. Two types of Cdk1 inhibitory kinases have been found in metazoans. They differ in subcellular localization and Cdk1 target-site specificity: one (Wee1) being nuclear and the other (Myt1), membrane-associated and cytoplasmic. Drosophila has one representative of each: dMyt1 and dWee1. Although dWee1 and dMyt1 are not essential for zygotic viability, loss of both resulted in synthetic lethality, indicating that they are partially functionally redundant. Bristle defects in myt1 mutant adult flies prompted a phenotypic analysis that revealed cell-cycle defects, ectopic apoptosis, and abnormal responses to ionizing radiation in the myt1 mutant imaginal wing discs that give rise to these mechanosensory organs. Cdk1 inhibitory phosphorylation was also aberrant in these myt1 mutant imaginal wing discs, indicating that dMyt1 serves Cdk1 regulatory functions that are important both for normal cell-cycle progression and for coordinating mitosis with critical developmental processes.
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Colomina N, Ferrezuelo F, Wang H, Aldea M, Garí E. Whi3, a developmental regulator of budding yeast, binds a large set of mRNAs functionally related to the endoplasmic reticulum. J Biol Chem 2008; 283:28670-9. [PMID: 18667435 PMCID: PMC2661415 DOI: 10.1074/jbc.m804604200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 07/28/2008] [Indexed: 01/07/2023] Open
Abstract
Whi3 is an RNA-binding protein associated with the endoplasmic reticulum (ER) that binds the CLN3 mRNA and plays a key role in the efficient retention of cyclin Cln3 at the ER. In the present work, we have identified new Whi3-associated mRNAs by a genomic approach. A large and significant number of these Whi3 targets encode for membrane and exocytic proteins involved in processes such as transport and cell wall biogenesis. Consistent with the genomic data, we have observed that cell wall integrity is compromised in Whi3-deficient cells and found strong genetic interactions between WHI3 and the cell integrity pathway. Whi3-associated mRNAs are enriched in clusters of the tetranucleotide GCAU, and mutation of the GCAU clusters in the CLN3 mRNA caused a reduction in its association to Whi3, suggesting that these sequences may act as cis-determinants for binding. Our data suggest that Whi3 is involved in the regulation and/or localization of a large subset of mRNAs functionally related to the ER and, since it is important for different molecular processes such as cytoplasmic retention or exocytic traffic of proteins, we propose that Whi3 is a general modulator of protein fate in budding yeast.
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Affiliation(s)
- Neus Colomina
- Departament de Ciències Mèdiques Bàsiques, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, Montserrat Roig 2, 25008 Lleida, Catalonia, Spain
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Emerging cancer therapeutic opportunities by inhibiting mitotic kinases. Curr Opin Pharmacol 2008; 8:375-83. [PMID: 18644252 DOI: 10.1016/j.coph.2008.06.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 06/19/2008] [Accepted: 06/20/2008] [Indexed: 11/22/2022]
Abstract
Among cellular kinases, several cell cycle protein kinases play critical roles in mitotic entry and chromosome segregation. Inhibition of these proteins frequently results in dramatic mitotic arrest and subsequent apoptosis. Most drug discovery efforts have been directed against members of the cyclin-dependent kinase (CDK), Aurora and Polo-like kinase families. Inhibition of these proteins with small molecules has emerged as a powerful research tool and their clinical use is currently being tested in phase I and phase II trials for cancer therapy. New unexplored kinases or new protein domains distinct to the kinase pocket are now being evaluated for the next generation of mitotic drugs. The therapeutic value of inhibiting these kinases will improve with the availability of new specific and potent inhibitors, but it will also rely on a better knowledge of the physiological requirement for these proteins in normal and tumor cell cycles.
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Keaton MA, Szkotnicki L, Marquitz AR, Harrison J, Zyla TR, Lew DJ. Nucleocytoplasmic trafficking of G2/M regulators in yeast. Mol Biol Cell 2008; 19:4006-18. [PMID: 18562688 DOI: 10.1091/mbc.e08-03-0286] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Nucleocytoplasmic shuttling is prevalent among many cell cycle regulators controlling the G2/M transition. Shuttling of cyclin/cyclin-dependent kinase (CDK) complexes is thought to provide access to substrates stably located in either compartment. Because cyclin/CDK shuttles between cellular compartments, an upstream regulator that is fixed in one compartment could in principle affect the entire cyclin/CDK pool. Alternatively, the regulators themselves may need to shuttle to effectively regulate their moving target. Here, we identify localization motifs in the budding yeast Swe1p (Wee1) and Mih1p (Cdc25) cell cycle regulators. Replacement of endogenous Swe1p or Mih1p with mutants impaired in nuclear import or export revealed that the nuclear pools of Swe1p and Mih1p were more effective in CDK regulation than were the cytoplasmic pools. Nevertheless, shuttling of cyclin/CDK complexes was sufficiently rapid to coordinate nuclear and cytoplasmic events even when Swe1p or Mih1p were restricted to one compartment. Additionally, we found that Swe1p nuclear export was important for its degradation. Because Swe1p degradation is regulated by cytoskeletal stress, shuttling of Swe1p between nucleus and cytoplasm serves to couple cytoplasmic stress to nuclear cyclin/CDK inhibition.
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Affiliation(s)
- Mignon A Keaton
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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Leslie M. Career change for a mitotic protein. J Biophys Biochem Cytol 2008. [PMCID: PMC2287279 DOI: 10.1083/jcb.1811iti2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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