1
|
Sosnovski KE, Braun T, Amir A, BenShoshan M, Abbas-Egbariya H, Ben-Yishay R, Anafi L, Avivi C, Barshack I, Denson LA, Haberman Y. Reduced LHFPL3-AS2 lncRNA expression is linked to altered epithelial polarity and proliferation, and to ileal ulceration in Crohn disease. Sci Rep 2023; 13:20513. [PMID: 37993670 PMCID: PMC10665440 DOI: 10.1038/s41598-023-47997-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/21/2023] [Indexed: 11/24/2023] Open
Abstract
Disruption of intestinal epithelial functions is linked to Crohn disease (CD) pathogenesis. We identified a widespread reduction in the expression of long non-coding RNAs (lncRNAs) including LHFPL3-AS2 in the treatment-naïve CD ileum of the RISK pediatric cohort. We validated the reduction of LHFPL3-AS2 in adult CD and noted a further reduction in patients with more severe CD from the RISK cohort. LHFPL3-AS2 knockdown in Caco-2 cells robustly affected epithelial monolayer morphogenesis with markedly reduced confluency and spreading, showing atypical rounding, and clumping. mRNA-seq analysis of LHFPL3-AS2 knockdown cells highlighted the reduction of genes and pathways linked with apical polarity, actin bundles, morphogenesis, and the b-catenin-TCF4 complex. LHFPL3-AS2 knockdown significantly reduced the ability of cells to form an internal lumen within the 3-dimensional (3D) cyst model, with mislocalization of actin and adherent and tight junction proteins, affecting epithelial polarity. LHFPL3-AS2 knockdown also resulted in defective mitotic spindle formation and consequent reduction in epithelial proliferation. Altogether, we show that LHFPL3-AS2 reduction affects epithelial morphogenesis, polarity, mitotic spindle formation, and proliferation, which are key processes in maintaining epithelial homeostasis in CD. Reduced expression of LHFPL3-AS2 in CD patients and its further reduction with ileal ulceration outcome, emphasizes its significance in this context.
Collapse
Affiliation(s)
- Katya E Sosnovski
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Tzipi Braun
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
| | - Amnon Amir
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
| | - Marina BenShoshan
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Haya Abbas-Egbariya
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rakefet Ben-Yishay
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
| | - Liat Anafi
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
| | - Camilla Avivi
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
| | - Iris Barshack
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lee A Denson
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Yael Haberman
- Sheba Medical Center, Tel-Hashomer, Affiliated with the Tel Aviv University, Tel Aviv, Israel.
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| |
Collapse
|
2
|
Weier AK, Homrich M, Ebbinghaus S, Juda P, Miková E, Hauschild R, Zhang L, Quast T, Mass E, Schlitzer A, Kolanus W, Burgdorf S, Gruß OJ, Hons M, Wieser S, Kiermaier E. Multiple centrosomes enhance migration and immune cell effector functions of mature dendritic cells. J Cell Biol 2022; 221:213533. [PMID: 36214847 PMCID: PMC9555069 DOI: 10.1083/jcb.202107134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 03/01/2022] [Accepted: 09/12/2022] [Indexed: 12/13/2022] Open
Abstract
Centrosomes play a crucial role during immune cell interactions and initiation of the immune response. In proliferating cells, centrosome numbers are tightly controlled and generally limited to one in G1 and two prior to mitosis. Defects in regulating centrosome numbers have been associated with cell transformation and tumorigenesis. Here, we report the emergence of extra centrosomes in leukocytes during immune activation. Upon antigen encounter, dendritic cells pass through incomplete mitosis and arrest in the subsequent G1 phase leading to tetraploid cells with accumulated centrosomes. In addition, cell stimulation increases expression of polo-like kinase 2, resulting in diploid cells with two centrosomes in G1-arrested cells. During cell migration, centrosomes tightly cluster and act as functional microtubule-organizing centers allowing for increased persistent locomotion along gradients of chemotactic cues. Moreover, dendritic cells with extra centrosomes display enhanced secretion of inflammatory cytokines and optimized T cell responses. Together, these results demonstrate a previously unappreciated role of extra centrosomes for regular cell and tissue homeostasis.
Collapse
Affiliation(s)
- Ann-Kathrin Weier
- Life and Medical Sciences Institute, Immune and Tumor Biology, University of Bonn, Bonn, Germany
| | - Mirka Homrich
- Life and Medical Sciences Institute, Immune and Tumor Biology, University of Bonn, Bonn, Germany
| | - Stephanie Ebbinghaus
- Life and Medical Sciences Institute, Immune and Tumor Biology, University of Bonn, Bonn, Germany
| | - Pavel Juda
- BIOCEV, First Faculty of Medicine, Charles University, Vestec, Czech Republic
| | - Eliška Miková
- BIOCEV, First Faculty of Medicine, Charles University, Vestec, Czech Republic
| | - Robert Hauschild
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Lili Zhang
- Life and Medical Sciences Institute, Quantitative Systems Biology, University of Bonn, Bonn, Germany
| | - Thomas Quast
- Life and Medical Sciences Institute, Molecular Immunology and Cell Biology, University of Bonn, Bonn, Germany
| | - Elvira Mass
- Life and Medical Sciences Institute, Developmental Biology of the Immune System, University of Bonn, Bonn, Germany
| | - Andreas Schlitzer
- Life and Medical Sciences Institute, Quantitative Systems Biology, University of Bonn, Bonn, Germany
| | - Waldemar Kolanus
- Life and Medical Sciences Institute, Molecular Immunology and Cell Biology, University of Bonn, Bonn, Germany
| | - Sven Burgdorf
- Life and Medical Sciences Institute, Cellular Immunology, University of Bonn, Bonn, Germany
| | - Oliver J. Gruß
- Institute of Genetics, University of Bonn, Bonn, Germany
| | - Miroslav Hons
- BIOCEV, First Faculty of Medicine, Charles University, Vestec, Czech Republic
| | - Stefan Wieser
- Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Eva Kiermaier
- Life and Medical Sciences Institute, Immune and Tumor Biology, University of Bonn, Bonn, Germany,Correspondence to Eva Kiermaier:
| |
Collapse
|
3
|
Zhang RK, Wang P, Lu YC, Lang L, Wang L, Lee SC. Cadmium induces cell centrosome amplification via reactive oxygen species as well as endoplasmic reticulum stress pathway. J Cell Physiol 2019; 234:18230-18248. [DOI: 10.1002/jcp.28455] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 02/06/2019] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Rui Kai Zhang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Pu Wang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Yu Cheng Lu
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Lang Lang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Lan Wang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Shao Chin Lee
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
- Department of Biology, School of Life Sciences Jiangsu Normal University Xuzhou Jiangsu People's Republic of China
| |
Collapse
|
4
|
Graciotti M, Fang Z, Johnsson K, Gönczy P. Chemical Genetic Screen Identifies Natural Products that Modulate Centriole Number. Chembiochem 2016; 17:2063-2074. [DOI: 10.1002/cbic.201600327] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Michele Graciotti
- Institute of Chemical Sciences and Engineering; Swiss Federal Institute of Technology Lausanne (EPFL); 1015 Lausanne Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology; 1015 Lausanne Switzerland
| | - Zhou Fang
- Swiss Institute for Experimental Cancer Research (ISREC); Swiss Federal Institute of Technology Lausanne (EPFL); 1015 Lausanne Switzerland
| | - Kai Johnsson
- Institute of Chemical Sciences and Engineering; Swiss Federal Institute of Technology Lausanne (EPFL); 1015 Lausanne Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology; 1015 Lausanne Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC); Swiss Federal Institute of Technology Lausanne (EPFL); 1015 Lausanne Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology; 1015 Lausanne Switzerland
| |
Collapse
|
5
|
Kubota S, Fukumoto Y, Ishibashi K, Soeda S, Kubota S, Yuki R, Nakayama Y, Aoyama K, Yamaguchi N, Yamaguchi N. Activation of the prereplication complex is blocked by mimosine through reactive oxygen species-activated ataxia telangiectasia mutated (ATM) protein without DNA damage. J Biol Chem 2014; 289:5730-46. [PMID: 24421316 DOI: 10.1074/jbc.m113.546655] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mimosine is an effective cell synchronization reagent used for arresting cells in late G1 phase. However, the mechanism underlying mimosine-induced G1 cell cycle arrest remains unclear. Using highly synchronous cell populations, we show here that mimosine blocks S phase entry through ATM activation. HeLa S3 cells are exposed to thymidine for 15 h, released for 9 h by washing out the thymidine, and subsequently treated with 1 mM mimosine for a further 15 h (thymidine → mimosine). In contrast to thymidine-induced S phase arrest, mimosine treatment synchronizes >90% of cells at the G1-S phase boundary by inhibiting the transition of the prereplication complex to the preinitiation complex. Mimosine treatment activates ataxia telangiectasia mutated (ATM)/ataxia telangiectasia and Rad3-related (ATR)-mediated checkpoint signaling without inducing DNA damage. Inhibition of ATM activity is found to induce mimosine-arrested cells to enter S phase. In addition, ATM activation by mimosine treatment is mediated by reactive oxygen species (ROS). These results suggest that, upon mimosine treatment, ATM blocks S phase entry in response to ROS, which prevents replication fork stalling-induced DNA damage.
Collapse
Affiliation(s)
- Shoichi Kubota
- From the Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Centrosomes and the Art of Mitotic Spindle Maintenance. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 313:179-217. [DOI: 10.1016/b978-0-12-800177-6.00006-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
7
|
Kaczanowski A, Kiersnowska M. Inactivation of a macronuclear intra-S-phase checkpoint in Tetrahymena thermophila with caffeine affects the integrity of the micronuclear genome. Protist 2011; 162:616-36. [PMID: 21601521 DOI: 10.1016/j.protis.2011.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 01/23/2011] [Indexed: 01/16/2023]
Abstract
Aphidicolin (APH), an inhibitor of DNA polymerase α, arrested cell divisions in Tetrahymena thermophila. Surprisingly, low concentrations of APH induced an increase of macronuclear DNA content and cell size in non-dividing cells. In spite of the cell size increase, most proliferation of basal bodies, ciliogenesis and development of new oral primordia were prevented by the APH treatment. The division arrest induced by APH was partly overridden by caffeine (CAF) treatment, which caused the fragmentation ("pulverization") of the chromosomes in G2 micronuclei. Somatic progeny of dividers with pulverized micronuclei (APH+CAF strains) contained aneuploid and amicronucleate cells. The amicronucleate cells, after losing their oral structures and most of their cilia, and undergoing progressive disorganization of cortical structures, assumed an irregular shape ("crinkled") and were nonviable. "Crinkled" cells were not formed after APH + CAF treatment of the amicronuclear BI3840 strain, which contains some mic-specific sequences in its macronucleus. Most of the APH +CAF strains had a typical "*"- like conjugation phenotype: they did not produce pronuclei, but received them unilaterally from their mates and retained old macronuclei. However, 4 among 100 APH+CAF clones induced arrest at meiotic metaphase I in their wt mates. It is likely that the origin of such clones was enhanced by chromosome pulverization.
Collapse
|
8
|
Lai PY, Wang CY, Chen WY, Kao YH, Tsai HM, Tachibana T, Chang WC, Chung BC. Steroidogenic Factor 1 (NR5A1) resides in centrosomes and maintains genomic stability by controlling centrosome homeostasis. Cell Death Differ 2011; 18:1836-44. [PMID: 21566663 DOI: 10.1038/cdd.2011.54] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
SF-1 (Steroidogenic Factor 1, NR5A1) is a tissue-specific transcription factor critical for the growth, development and differentiation of steroidogenic and a few other endocrine tissues. But how SF-1 regulates cell growth is not entirely clear. Here we found that SF-1 was localized to the centrosome in addition to the nucleus, and SF-1 depletion by shRNA caused centrosome over-duplication, aberrant mitosis and genomic instability, leading to a reduction of cell number. Centrosome amplification defect was rescued by both wild-type SF-1 and transcription-defective SF-1-G35E, suggesting a non-genomic activity of SF-1 involved in centrosome homeostasis. In addition, we identified in SF-1 a centrosome localization signal, whose overexpression led to reduced localization of both SF-1 and γ-tubulin to the centrosome. Our results uncover a novel role of SF-1 in the control of centrosome homeostasis and genomic stability.
Collapse
Affiliation(s)
- P-Y Lai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Rafelski SM, Keller LC, Alberts JB, Marshall WF. Apparent diffusive motion of centrin foci in living cells: implications for diffusion-based motion in centriole duplication. Phys Biol 2011; 8:026010. [PMID: 21378439 DOI: 10.1088/1478-3975/8/2/026010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The degree to which diffusion contributes to positioning cellular structures is an open question. Here we investigate the question of whether diffusive motion of centrin granules would allow them to interact with the mother centriole. The role of centrin granules in centriole duplication remains unclear, but some proposed functions of these granules, for example, in providing pre-assembled centriole subunits, or by acting as unstable 'pre-centrioles' that need to be captured by the mother centriole (La Terra et al 2005 J. Cell Biol. 168 713-22), require the centrin foci to reach the mother. To test whether diffusive motion could permit such interactions in the necessary time scale, we measured the motion of centrin-containing foci in living human U2OS cells. We found that these centrin foci display apparently diffusive undirected motion. Using the apparent diffusion constant obtained from these measurements, we calculated the time scale required for diffusion to capture by the mother centrioles and found that it would greatly exceed the time available in the cell cycle. We conclude that mechanisms invoking centrin foci capture by the mother, whether as a pre-centriole or as a source of components to support later assembly, would require a form of directed motility of centrin foci that has not yet been observed.
Collapse
Affiliation(s)
- Susanne M Rafelski
- UCSF Department of Biochemistry and Biophysics, GH-N372F Genentech Hall, 600 16th St, San Francisco, CA 94158, USA
| | | | | | | |
Collapse
|
10
|
Harrison MK, Adon AM, Saavedra HI. The G1 phase Cdks regulate the centrosome cycle and mediate oncogene-dependent centrosome amplification. Cell Div 2011; 6:2. [PMID: 21272329 PMCID: PMC3038874 DOI: 10.1186/1747-1028-6-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 01/27/2011] [Indexed: 11/10/2022] Open
Abstract
Because centrosome amplification generates aneuploidy and since centrosome amplification is ubiquitous in human tumors, a strong case is made for centrosome amplification being a major force in tumor biogenesis. Various evidence showing that oncogenes and altered tumor suppressors lead to centrosome amplification and aneuploidy suggests that oncogenes and altered tumor suppressors are a major source of genomic instability in tumors, and that they generate those abnormal processes to initiate and sustain tumorigenesis. We discuss how altered tumor suppressors and oncogenes utilize the cell cycle regulatory machinery to signal centrosome amplification and aneuploidy.
Collapse
Affiliation(s)
- Mary K Harrison
- Emory University, Department of Radiation Oncology, Winship Cancer Institute, 1701 Uppergate Drive, Atlanta, Georgia, 30322, USA.
| | | | | |
Collapse
|
11
|
Collins ES, Hornick JE, Durcan TM, Collins NS, Archer W, Karanjeet KB, Vaughan KT, Hinchcliffe EH. Centrosome biogenesis continues in the absence of microtubules during prolonged S-phase arrest. J Cell Physiol 2010; 225:454-65. [PMID: 20458743 DOI: 10.1002/jcp.22222] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
When CHO cells are arrested in S-phase, they undergo repeated rounds of centrosome duplication without cell-cycle progression. While the increase is slow and asynchronous, the number of centrosomes in these cells does rise with time. To investigate mechanisms controlling this duplication, we have arrested CHO cells in S-phase for up to 72 h, and coordinately inhibited new centriole formation by treatment with the microtubule poison colcemid. We find that in such cells, the pre-existing centrosomes remain, and a variable number of foci--containing alpha/gamma-tubulin and centrin 2--assemble at the nuclear periphery. When the colcemid is washed out, the nuclear-associated foci disappear, and cells assemble new centriole-containing centrosomes, which accumulate the centriole scaffold protein SAS-6, nucleate microtubule asters, and form functional mitotic spindle poles. The number of centrosomes that assemble following colcemid washout increases with duration of S-phase arrest, even though the number of nuclear-associated foci or pre-existing centrosomes does not increase. This suggests that during S-phase, a cryptic generative event occurs repeatedly, even in the absence of new triplet microtubule assembly. When triplet microtubule assembly is restored, these cryptic generative events become realized, and multiple centriole-containing centrosomes assemble.
Collapse
Affiliation(s)
- Elizabeth S Collins
- Cellular Dynamics Section, The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Oikonomou C, Cross FR. Frequency control of cell cycle oscillators. Curr Opin Genet Dev 2010; 20:605-12. [PMID: 20851595 DOI: 10.1016/j.gde.2010.08.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 08/02/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
Abstract
The cell cycle oscillator, based on a core negative feedback loop and modified extensively by positive feedback, cycles with a frequency that is regulated by environmental and developmental programs to encompass a wide range of cell cycle times. We discuss how positive feedback allows frequency tuning, how size and morphogenetic checkpoints regulate oscillator frequency, and how extrinsic oscillators such as the circadian clock gate cell cycle frequency. The master cell cycle regulatory oscillator in turn controls the frequency of peripheral oscillators controlling essential events. A recently proposed phase-locking model accounts for this coupling.
Collapse
|
13
|
Frisa PS, Jacobberger JW. Cytometry of chromatin bound Mcm6 and PCNA identifies two states in G1 that are separated functionally by the G1 restriction point. BMC Cell Biol 2010; 11:26. [PMID: 20398392 PMCID: PMC2882901 DOI: 10.1186/1471-2121-11-26] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 04/16/2010] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Cytometric measurements of DNA content and chromatin-bound Mcm2 have demonstrated bimodal patterns of expression in G1. These patterns, the replication licensing function of Mcm proteins, and a correlation between Mcm loading and cell cycle commitment for cells re-entering the cell cycle, led us to test the idea that cells expressing a defined high level of chromatin-bound Mcm6 in G1 are committed--i.e., past the G1 restriction point. We developed a cell-based assay for tightly-bound PCNA (PCNA*) and Mcm6 (Mcm6*), DNA content, and a mitotic marker to clearly define G1, S, G2, and M phases of the cell cycle. hTERT-BJ1, hTERT-RPE-1, and Molt4 cells were extracted with Triton X-100 followed by methanol fixation, stained with antibodies and DAPI, then measured by cytometry. RESULTS Bivariate analysis of cytometric data demonstrated complex patterns with distinct clustering for all combinations of the 4 variables. In G1, cells clustered in two groups characterized by low and high Mcm6* expression. Serum starvation and release experiments showed that residence in the high group was in late G1, just prior to S phase. Kinetic experiments, employing serum withdrawal, and stathmokinetic analysis with aphidicolin, mimosine or nocodazole demonstrated that cells with high levels of Mcm6* cycled with the committed phases of the cell cycle (S, G2, and M). CONCLUSIONS A multivariate assay for Mcm6*, PCNA*, DNA content, and a mitotic marker provides analysis capable of estimating the fraction of pre and post-restriction point G1 cells and supports the idea that there are at least two states in G1 defined by levels of chromatin bound Mcm proteins.
Collapse
Affiliation(s)
- Phyllis S Frisa
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | | |
Collapse
|
14
|
Riparbelli MG, Colozza G, Callaini G. Procentriole elongation and recruitment of pericentriolar material are downregulated in cyst cells as they enter quiescence. J Cell Sci 2009; 122:3613-8. [PMID: 19755490 DOI: 10.1242/jcs.049957] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The apical region of the Drosophila testis contains a niche with two stem cell populations: germline stem cells (GSCs) and cyst progenitor cells (CPCs). Asymmetrical division of these stem cells leads to gonioblast daughters (which undergo further mitoses) and cyst cell daughters (which withdraw from the cell cycle and become quiescent). Although a considerable body of evidence indicates important roles for centrosomes in spindle orientation and asymmetrical division of GSCs, the behaviour and function of the centrioles in CPCs and their daughters remain unknown. Here, we show that quiescent cyst cells lose centrosome components after two divisions of the spermatogonia they envelop, but keep the centriolar component SAS-6. Cyst cells do have centriole pairs, but they are formed by a mother and a very short daughter that does not elongate or mature. The presence of procentrioles in quiescent cyst cells suggests that the centriole duplication cycle is uncoupled from the G1-S transition and that it might begin even earlier, in mitosis. Failure to enter the cell cycle might result in the improper recruitment of centriolar components at the mother centriole, thus hampering the full elongation of its daughter. Procentriole maturation defects could thus lead to the inability to maintain centrosomal components during development.
Collapse
|
15
|
Strnad P, Gönczy P. Mechanisms of procentriole formation. Trends Cell Biol 2008; 18:389-96. [PMID: 18620859 DOI: 10.1016/j.tcb.2008.06.004] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 06/03/2008] [Accepted: 06/11/2008] [Indexed: 01/05/2023]
Abstract
The centrosome comprises a pair of centrioles and associated pericentriolar material, and it is the principal microtubule-organizing centre of most animal cells. Like the genetic material, the centrosome is duplicated once and only once during the cell cycle. Despite the fact that both doubling events are crucial for genome integrity, the understanding of the mechanisms governing centrosome duplication has lagged behind the fuller knowledge of DNA replication. Here, we review recent findings that provide important mechanistic insights into how a single procentriole forms next to each centriole once per cell cycle, thus ensuring that one centrosome becomes two.
Collapse
Affiliation(s)
- Petr Strnad
- Swiss Institute for Experimental Cancer Research (ISREC), Swiss Federal Institute of Technology (EPFL), School of Life Sciences, Lausanne, Switzerland
| | | |
Collapse
|
16
|
Durcan TM, Halpin ES, Rao T, Collins NS, Tribble EK, Hornick JE, Hinchcliffe EH. Tektin 2 is required for central spindle microtubule organization and the completion of cytokinesis. ACTA ACUST UNITED AC 2008; 181:595-603. [PMID: 18474621 PMCID: PMC2386100 DOI: 10.1083/jcb.200711160] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
During anaphase, the nonkinetochore microtubules in the spindle midzone become compacted into the central spindle, a structure which is required to both initiate and complete cytokinesis. We show that Tektin 2 (Tek2) associates with the spindle poles throughout mitosis, organizes the spindle midzone microtubules during anaphase, and assembles into the midbody matrix surrounding the compacted midzone microtubules during cytokinesis. Tek2 small interfering RNA (siRNA) disrupts central spindle organization and proper localization of MKLP1, PRC1, and Aurora B to the midzone and prevents the formation of a midbody matrix. Video microscopy revealed that loss of Tek2 results in binucleate cell formation by aberrant fusion of daughter cells after cytokinesis. Although a myosin II inhibitor, blebbistatin, prevents actin-myosin contractility, the microtubules of the central spindle are compacted. Strikingly, Tek2 siRNA abolishes this actin-myosin-independent midzone microtubule compaction. Thus, Tek2-dependent organization of the central spindle during anaphase is essential for proper midbody formation and the segregation of daughter cells after cytokinesis.
Collapse
Affiliation(s)
- Thomas M Durcan
- Department of Biological Sciences and Notre Dame Integrated Imaging Facility, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | | | | | | | | | | |
Collapse
|