Document Detail

Cyclin A2, Rho GTPases and EMT.
Jump to Full Text
MedLine Citation:
PMID:  22735340     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Cell cycle regulators, such as cyclins, are often upregulated in many proliferative disorders, and Cyclin A2 is generally considered as a marker of aggressive cancers. Our recent work, which revealed decreased expression of Cyclin A2 upon metastasis of colorectal cancer, suggests a more complicated situation. Consistent with this, we identified a role for Cyclin A2, via RhoA, in regulation of the actin cytoskeleton and the control of cell invasion. Cyclin A2 also regulates spindle orientation which, when misoriented, could disrupt cell polarity and favor cancer cell detachment from the tumor as part of a transforming process, such as epithelial to mesenchymal transition (EMT). During EMT, cells undergo morphological and molecular changes toward a mesenchymal phenotype. Upregulation, or increased activity of some Rho GTPases, such as Cdc42, Rac1 or RhoC, increases the invasive potential of these cells. This correlates with the inverse relationship between RhoA and RhoC activities we observed in an epithelial cell type. Altogether, these observations raise the possibility that Cyclin A2 is instrumental in preventing EMT and therefore cancers of epithelial tissues.
Authors:
Nawal Bendris; Nikola Arsic; Bénédicte Lemmers; Jean Marie Blanchard
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-06-27
Journal Detail:
Title:  Small GTPases     Volume:  3     ISSN:  2154-1256     ISO Abbreviation:  Small GTPases     Publication Date:    2012 Oct-Dec
Date Detail:
Created Date:  2012-12-14     Completed Date:  2013-05-21     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  101530974     Medline TA:  Small GTPases     Country:  United States    
Other Details:
Languages:  eng     Pagination:  225-8     Citation Subset:  IM    
Affiliation:
UT Southwestern Medical Center, Dallas, TX, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Animals
Cell Transformation, Neoplastic
Cyclin A2 / metabolism*
Epithelial-Mesenchymal Transition / physiology*
Humans
Neoplasms / metabolism*
rho GTP-Binding Proteins / metabolism*
Chemical
Reg. No./Substance:
0/Cyclin A2; EC 3.6.5.2/rho GTP-Binding Proteins
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Full Text
Journal Information
Journal ID (nlm-ta): Small GTPases
Journal ID (iso-abbrev): Small GTPases
Journal ID (publisher-id): SGTP
ISSN: 2154-1248
ISSN: 2154-1256
Publisher: Landes Bioscience
Article Information
Download PDF
Copyright © 2012 Landes Bioscience
open-access:
Print publication date: Day: 01 Month: 10 Year: 2012
pmc-release publication date: Day: 01 Month: 10 Year: 2012
Volume: 3 Issue: 4
First Page: 225 Last Page: 228
PubMed Id: 22735340
ID: 3520886
Publisher Id: 2012SGTP0021
Publisher Item Identifier: 20791
DOI: 10.4161/sgtp.20791

Cyclin A2, Rho GTPases and EMT
Nawal Bendris1
Nikola Arsic2
Bénédicte Lemmers3*
Jean Marie Blanchard3*
1UT Southwestern Medical Center; Dallas, TX USA
2Centre de Recherche de Biochimie Macromoléculaire; Montpellier, France
3Institut de Génétique Moléculaire de Montpellier; CNRS; Montpellier, France
*Correspondence to: Bénédicte Lemmers, Email: benedicte.lemmers@igmm.cnrs.fr and Jean Marie Blanchard, Email: jean-marie.blanchard@igmm.cnrs.fr

Recent data pointing to a novel function of Cyclin A2 add another component to the complex regulatory network that involves cell cycle regulators and cytoskeletal structures participating in the control of cell movement.1 As already known, Cyclin A2 is a key regulator of cell division, since it controls both S phase and G2/M transition in association with CDK2 and CDK1, respectively.2 During S phase, Cyclin A2 regulates the initiation and progression of DNA synthesis, and at the G2/M transition, it plays a critical role in triggering Cyclin B1-CDK1 activation.3-5 In mice, it is essential in embryonic cells and in the hematopoietic lineage, yet dispensable in fibroblasts.6,7

Surprisingly, depletion of Cyclin A2 is sufficient to increase cell motility of fibroblasts in 2D assays and cooperates with oncogenic transformation to increase their invasiveness in 3D collagen matrixes.1 Cyclin A2-deficient cells contain a perturbed cytoskeleton, where Actin filaments are cortical and the distribution of focal adhesions is altered. Interestingly, these defects are corrected by a Cyclin A2 mutant unable to activate its cognate kinases, CDK1 and CDK2. This is associated with a downregulation of the RhoA-ROCK pathway and decreased phosphorylation of Cofilin, which is involved in the reorganization of Actin filaments, consecutively leading to an increased cell migration and invasion. Importantly, pharmacological inhibition of ROCK in control fibroblasts leads to an increase in migration velocity similar to that of Cyclin A2-depleted cells.

Cyclin D1 and the CDK inhibitors p21, p27 and p57 had also previously been shown to impinge upon the RhoA/ROCK pathway. Cyclin D1 binds directly to p27 and thereby blocks RhoA activation by inhibiting interaction with its GEF.8-11 Similarly, cytoplasmic p21 has been shown to bind and inhibit ROCK1, which promotes neurite extension by neuroblastoma cells and hippocampal neurons,12 while p57 was shown to sequester LIMK (Fig. 1).13 Within this scheme, Cyclin A2 binds directly to RhoA and facilitate its GTP loading by GEFs.1 This is consistent with the involvement of this GTPase in early mitosis, since its increased activity at that time leads to cortical retraction and cell rounding via its downstream effector ROCK.14 Moreover, formation of the contractile ring during cytokinesis has also been shown to depend upon RhoA activation in a precise zone at the cell equator.15

Knockdown of Cyclin A2 and inhibition of CDK2 prevent cells from forming stable attachments of their mitotic spindle to the cell cortex.16 This resulted in the spindles failing to locate to the central position in the cells and undergo dramatic rotation. Moreover, Cyclin A2-CDK2 specifically associated with APC in late G2 phase and phosphorylated it on Ser1360. Mutation of this serine to alanine results in identical off-centered mitotic spindles. Thus, this Cyclin A2-CDK2-dependent phosphorylation within the mutation cluster region of APC affects astral microtubule attachment to the cortical surface in mitosis.

Another potential player in this complex ballet appears to be the Golgi apparatus. Recent studies suggest the existence of functional interactions between this organelle and the centrosome, the structure responsible for the nucleation of the mitotic spindle. The Golgi and the centrosome are in a close proximity at interphase and this intimacy is transiently lost during mitosis, when the Golgi is fragmented, and the two newly duplicated centrosomes migrate. Golgi-centrosomes interactions may play a central role in cell polarization, since both structures undergo re-orientation toward the leading edge of a migrating cell (for a review see ref. 17). Proteins of the Golgi apparatus are likely to be instrumental in centrosome organization and positioning, and microtubules nucleated at the centrosome seem to play the same role for the Golgi. CyclinA2 has also been shown to localize to the centrosome in a CDK-independent manner, and through binding of MCM5 and Orc1, prevents the formation of supernumerary centrosomes.18 Since Cdc42 plays a central role in cell polarization, this raises the question of its role in the potential coupling of this process to centrosome duplication and spindle orientation. A partial answer to this question was provided recently. Bray et al. showed that Cdc42 controls spindle orientation to position the apical surface during epithelial morphogenesis, at least in vitro.19

These data highlight thus another aspect of Cyclin A2 function in the control of cytoskeleton dynamics, which places this cyclin at the crossroads of intracellular processes, such as mitosis, and extracellular cues emanating from neighboring cells or from the extracellular matrix (Fig. 2).

If we place these observations within the context of the epithelium, the orientation of the mitotic spindle with respect to the lamina is a major issue, since this has been proposed to be instrumental in the determination of the fate of the two daughter cells. Moreover, in tumors, basal extrusion of a daughter cell could initiate metastasis in some situations.20 Therefore, mutations that couple spindle misorentiation with oncogene activation could facilitate tumor progression and metastasis spreading.

Until recently, Cyclin A2 was solely considered as a proliferation marker since, consistent with its known functions during the cell cycle, it is frequently overexpressed in highly proliferative cancers.3 However, our observations indicate that Cyclin A2 protein levels are significantly lower in an invasive colon carcinoma cell line derived from lymph node metastasis relative to a less-invasive counterpart issued from the primary site. More importantly, the same is observed upon metastasis of colon adenocarcinoma.1 Studies of renal, colorectal carcinoma and prostate cancer, found that proliferative tumors with low levels of Cyclin A2 were more aggressive than those with high Cyclin A2 expression.21-23 Moreover, Wang et al. established that Cyclin A2 levels were inversely correlated with invasiveness of oral squamous cell carcinoma (OSCC) both in vitro and in vivo.24

Altogether, these data indicate that Cyclin A2 downregulation could be an important step in the acquisition of an invasive property by epithelial cells, and thereby call for more studies on the involvement of this cyclin in the morphological changes that occur during metastasis. Along these lines, the epithelial to mesenchymal transition (EMT) appears to be instrumental in pathological situations such as fibrosis, tumor development and metastasis spreading.25-27 In the context of epithelial cancer, EMT provides one mechanism for tumor cells to invade the local tissue and blood vessels, setting the stage for metastatic spread. Therefore, EMT is hypothesized to contribute to tumor progression, and clinical evidence suggests that upregulation of EMT regulators in cancer cells correlates with poor patient outcome and tumor aggressiveness.28-30 EMT is likely to be triggered by complex networks of signals emanating from the tumor stroma, along with a variety of cytokines and growth factors, such as transforming growth factor β (TGFβ),31 epidermal growth factor (EGF),32 fibroblast growth factor (FGF)33 andhepatocyte growth factor (HGF).34 Consistent with this, Ras and TGFβ have been shown to cooperate in promoting EMT.35 During this process, epithelial cells undergo morphological remodeling toward a more elongated and fibroblastic morphology. Among these changes, cells lose cell-to-cell junctions, undergo Actin cytoskeleton rearrangement and acquire enhanced invasive properties. At the molecular level, EMT is characterized by a loss of E-cadherin, and the acquisition of mesenchymal markers, such as Vimentin, Fibronectin or N-cadherin. Transcription factors, such as Snail, Slug, Twist or Zeb-1 and 2, have been implicated in this process.36 For some cell types, the acquisition of a more motile phenotype during EMT has been attributed to the increased expression and activation of Rho GTPases, such as Rac1, Cdc42 and RhoC.37-39

Accordingly, overexpression of RhoC enhances the ability of melanoma cells to exit the circulatory system and colonize the lungs. Consistent with this, loss of RhoC does not affect tumor development while it leads to a drastic inhibition of metastasis. Nevertheless, RhoC-deficient mice are viable, indicating that this GTPase is dispensable for embryonic and post-natal development.40 RhoC and RhoA share more than 95% sequence similarity, thus it is not surprising that Cyclin A2 interacts as well with both GTPases.1,41 Indeed, when Cyclin A2 is knocked down in epithelial cells, such as normal mouse mammary epithelial cells (NMuMG), they exibit a strong downregulation of RhoA activity and an increase in RhoC activity (our unpublished observation).

Several reports support a possible role for RhoC in the EMT-related invasion and in metastasis spreading. As mentioned earlier, the breeding of RhoC-deficient mice to the tumor and metastasis-prone MMTV-PyMT strain established the requirement for RhoC in metastasis to the lungs.40 Consistent with this, increased RhoC expression in adenocarcinoma of pancreas,42 along with hepatocellular,43 breast,44 ovarian,45 bladder and esophageal cancers, has been observed and correlated with progression and poor prognosis.46 Moreover, invasion by several cell types, such as breast,47 colon carcinoma,48 or prostate cancer cell lines,49 was shown to be dependent on RhoC expression and activation. With regards to EMT, recent studies have established that increased expression and/or RhoC activation promotes invasion, whereas Rac1 and Cdc42 were generally considered as major players in this process.38,48 In these studies, increased RhoC activity is correlated with an increased transcription of the gene. This transcription is induced by upregulation of Twist and miR-10b, or is dependent on the transcription factor Ets-1 in breast cancer and colon carcinoma cell lines, respectively.38,48

In conclusion, these data highlight the intricate relationship between Cyclin A2 expression and Rho GTPases activity within the context of cell adhesion and motility. While Cdc42 had previously been shown to be instrumental for anchorage-independent expression of the Cylin A2 gene in primary mouse embryonic fibroblasts,50 this cyclin appears now to feed back on the activity of other GTPases, such as RhoA and RhoC. Altogether, these observations indicate that CyclinA2 is a potential novel player in the complex regulation of EMT, moreover, they reinforce the idea that cell cycle regulators are much more than just cell cycle regulators.


Notes

Previously published online: www.landesbioscience.com/journals/smallgtpases/article/20791

Acknowledgments

We thank Robert Hipskind for his kind review of our manuscript. This work and N. Arsic were supported by grants from Agence Nationale de la Recherche (BLANC06–3_142605), the Marie Curie reintegration program (MIRG-CT-2006–044922) and Association pour la Recherche contre le Cancer. N. Bendris was supported by a fellowship from the French Ministry of Education and Research and Fondation pour la Recherche Médicale.


Notes


References
1. Arsic N,Bendris N,Peter M,Begon-Pescia C,Rebouissou C,Gadéa G,et al. A novel function for Cyclin A2: control of cell invasion via RhoA signalingJ Cell BiolYear: 20121961476210.1083/jcb.20110208522232705
2. Pagano M,Pepperkok R,Verde F,Ansorge W,Draetta G. Cyclin A is required at two points in the human cell cycleEMBO JYear: 199211961711312467
3. Yam CH,Fung TK,Poon RY. Cyclin A in cell cycle control and cancerCell Mol Life SciYear: 20025913172610.1007/s00018-002-8510-y12363035
4. Fung TK,Ma HT,Poon RY. Specialized roles of the two mitotic cyclins in somatic cells: cyclin A as an activator of M phase-promoting factorMol Biol CellYear: 20071818617310.1091/mbc.E06-12-109217344473
5. De Boer L,Oakes V,Beamish H,Giles N,Stevens F,Somodevilla-Torres M,et al. Cyclin A/cdk2 coordinates centrosomal and nuclear mitotic eventsOncogeneYear: 2008274261810.1038/onc.2008.7418372919
6. Kalaszczynska I,Geng Y,Iino T,Mizuno S,Choi Y,Kondratiuk I,et al. Cyclin A is redundant in fibroblasts but essential in hematopoietic and embryonic stem cellsCellYear: 20091383526510.1016/j.cell.2009.04.06219592082
7. Murphy M,Stinnakre MG,Senamaud-Beaufort C,Winston NJ,Sweeney C,Kubelka M,et al. Delayed early embryonic lethality following disruption of the murine cyclin A2 geneNat GenetYear: 19971583610.1038/ng0197-838988174
8. Li Z,Jiao X,Wang C,Ju X,Lu Y,Yuan L,et al. Cyclin D1 induction of cellular migration requires p27(KIP1)Cancer ResYear: 20066699869410.1158/0008-5472.CAN-06-159617047061
9. Li Z,Wang C,Prendergast GC,Pestell RG. Cyclin D1 functions in cell migrationCell CycleYear: 200652440210.4161/cc.5.21.342817106256
10. Li Z,Wang C,Jiao X,Lu Y,Fu M,Quong AA,et al. Cyclin D1 regulates cellular migration through the inhibition of thrombospondin 1 and ROCK signalingMol Cell BiolYear: 20062642405610.1128/MCB.02124-0516705174
11. Besson A,Gurian-West M,Schmidt A,Hall A,Roberts JM. p27Kip1 modulates cell migration through the regulation of RhoA activationGenes DevYear: 2004188627610.1101/gad.118550415078817
12. Tanaka H,Yamashita T,Asada M,Mizutani S,Yoshikawa H,Tohyama M. Cytoplasmic p21(Cip1/WAF1) regulates neurite remodeling by inhibiting Rho-kinase activityJ Cell BiolYear: 2002158321910.1083/jcb.20020207112119358
13. Yokoo T,Toyoshima H,Miura M,Wang Y,Iida KT,Suzuki H,et al. p57Kip2 regulates actin dynamics by binding and translocating LIM-kinase 1 to the nucleusJ Biol ChemYear: 2003278529192310.1074/jbc.M30933420014530263
14. Maddox AS,Burridge K. RhoA is required for cortical retraction and rigidity during mitotic cell roundingJ Cell BiolYear: 20031602556510.1083/jcb.20020713012538643
15. Bement WM,Benink HA,von Dassow G. A microtubule-dependent zone of active RhoA during cleavage plane specificationJ Cell BiolYear: 20051709110110.1083/jcb.20050113115998801
16. Beamish H,de Boer L,Giles N,Stevens F,Oakes V,Gabrielli B. Cyclin A/cdk2 regulates adenomatous polyposis coli-dependent mitotic spindle anchoringJ Biol ChemYear: 2009284290152310.1074/jbc.M109.04282019703905
17. Sütterlin C,Colanzi A. The Golgi and the centrosome: building a functional partnershipJ Cell BiolYear: 2010188621810.1083/jcb.20091000120212314
18. Ferguson RL,Pascreau G,Maller JL. The cyclin A centrosomal localization sequence recruits MCM5 and Orc1 to regulate centrosome reduplicationJ Cell SciYear: 20101232743910.1242/jcs.07309820663915
19. Bray K,Brakebusch C,Vargo-Gogola T. The Rho GTPase Cdc42 is required for primary mammary epithelial cell morphogenesis in vitroSmall GtpasesYear: 201122475810.4161/sgtp.2.5.1816322292127
20. Slattum G,McGee KM,Rosenblatt J. P115 RhoGEF and microtubules decide the direction apoptotic cells extrude from an epitheliumJ Cell BiolYear: 200918669370210.1083/jcb.20090307919720875
21. Migita T,Oda Y,Naito S,Tsuneyoshi M. Low expression of p27(Kip1) is associated with tumor size and poor prognosis in patients with renal cell carcinomaCancerYear: 200294973910.1002/cncr.1033811920465
22. Li JQ,Miki H,Wu F,Saoo K,Nishioka M,Ohmori M,et al. Cyclin A correlates with carcinogenesis and metastasis, and p27(kip1) correlates with lymphatic invasion, in colorectal neoplasmsHum PatholYear: 20023310061510.1053/hupa.2002.12577412395374
23. Mashal RD,Lester S,Corless C,Richie JP,Chandra R,Propert KJ,et al. Expression of cell cycle-regulated proteins in prostate cancerCancer ResYear: 1996564159638797586
24. Wang YF,Chen JY,Chang SY,Chiu JH,Li WY,Chu PY,et al. Nm23-H1 expression of metastatic tumors in the lymph nodes is a prognostic indicator of oral squamous cell carcinomaInt J CancerYear: 20081223778610.1002/ijc.2309617918157
25. Kriz W,Kaissling B,Le Hir M. Epithelial-mesenchymal transition (EMT) in kidney fibrosis: fact or fantasy?J Clin InvestYear: 20111214687410.1172/JCI4459521370523
26. Chapman HA. Epithelial-mesenchymal interactions in pulmonary fibrosisAnnu Rev PhysiolYear: 2011734133510.1146/annurev-physiol-012110-14222521054168
27. Cheung C,Luo H,Yanagawa B,Leong HS,Samarasekera D,Lai JC,et al. Matrix metalloproteinases and tissue inhibitors of metalloproteinases in coxsackievirus-induced myocarditisCardiovasc PatholYear: 200615637410.1016/j.carpath.2005.11.00816533694
28. Zhang S, Wang X, Osunkoya AO, Iqbal S, Wang Y, Chen Z, et al. EPLIN downregulation promotes epithelial-mesenchymal transition in prostate cancer cells and correlates with clinical lymph node metastasis. Oncogene.
29. Ru GQ,Wang HJ,Xu WJ,Zhao ZS. Upregulation of Twist in gastric carcinoma associated with tumor invasion and poor prognosisPathol Oncol ResYear: 201117341710.1007/s12253-010-9332-021104359
30. Yang MH,Hsu DS,Wang HW,Wang HJ,Lan HY,Yang WH,et al. Bmi1 is essential in Twist1-induced epithelial-mesenchymal transitionNat Cell BiolYear: 2010129829210.1038/ncb209920818389
31. Zavadil J,Böttinger EP. TGF-beta and epithelial-to-mesenchymal transitionsOncogeneYear: 20052457647410.1038/sj.onc.120892716123809
32. Lo HW,Hsu SC,Xia W,Cao X,Shih JY,Wei Y,et al. Epidermal growth factor receptor cooperates with signal transducer and activator of transcription 3 to induce epithelial-mesenchymal transition in cancer cells via up-regulation of TWIST gene expressionCancer ResYear: 20076790667610.1158/0008-5472.CAN-07-057517909010
33. Acevedo VD,Gangula RD,Freeman KW,Li R,Zhang Y,Wang F,et al. Inducible FGFR-1 activation leads to irreversible prostate adenocarcinoma and an epithelial-to-mesenchymal transitionCancer CellYear: 2007125597110.1016/j.ccr.2007.11.00418068632
34. Savagner P,Yamada KM,Thiery JP. The zinc-finger protein slug causes desmosome dissociation, an initial and necessary step for growth factor-induced epithelial-mesenchymal transitionJ Cell BiolYear: 199713714031910.1083/jcb.137.6.14039182671
35. Larue L,Bellacosa A. Epithelial-mesenchymal transition in development and cancer: role of phosphatidylinositol 3′ kinase/AKT pathwaysOncogeneYear: 20052474435410.1038/sj.onc.120909116288291
36. Thiery JP,Sleeman JP. Complex networks orchestrate epithelial-mesenchymal transitionsNat Rev Mol Cell BiolYear: 200671314210.1038/nrm183516493418
37. Bosco EE,Mulloy JC,Zheng Y. Rac1 GTPase: a “Rac” of all tradesCell Mol Life SciYear: 200966370410.1007/s00018-008-8552-x19151919
38. Ma L,Teruya-Feldstein J,Weinberg RA. Tumour invasion and metastasis initiated by microRNA-10b in breast cancerNatureYear: 2007449682810.1038/nature0617417898713
39. Wilkinson S,Paterson HF,Marshall CJ. Cdc42-MRCK and Rho-ROCK signalling cooperate in myosin phosphorylation and cell invasionNat Cell BiolYear: 200572556110.1038/ncb123015723050
40. Hakem A,Sanchez-Sweatman O,You-Ten A,Duncan G,Wakeham A,Khokha R,et al. RhoC is dispensable for embryogenesis and tumor initiation but essential for metastasisGenes DevYear: 2005191974910.1101/gad.131080516107613
41. Wheeler AP,Ridley AJ. Why three Rho proteins? RhoA, RhoB, RhoC, and cell motilityExp Cell ResYear: 200430143910.1016/j.yexcr.2004.08.01215501444
42. Suwa H,Ohshio G,Imamura T,Watanabe G,Arii S,Imamura M,et al. Overexpression of the rhoC gene correlates with progression of ductal adenocarcinoma of the pancreasBr J CancerYear: 1998771475210.1038/bjc.1998.239459160
43. Wang W,Yang LY,Huang GW,Lu WQ,Yang ZL,Yang JQ,et al. Genomic analysis reveals RhoC as a potential marker in hepatocellular carcinoma with poor prognosisBr J CancerYear: 20049023495515150600
44. Fritz G,Brachetti C,Bahlmann F,Schmidt M,Kaina B. Rho GTPases in human breast tumours: expression and mutation analyses and correlation with clinical parametersBr J CancerYear: 2002876354410.1038/sj.bjc.660051012237774
45. Horiuchi A,Imai T,Wang C,Ohira S,Feng Y,Nikaido T,et al. Up-regulation of small GTPases, RhoA and RhoC, is associated with tumor progression in ovarian carcinomaLab InvestYear: 2003838617012808121
46. Faried A,Faried LS,Usman N,Kato H,Kuwano H. Clinical and prognostic significance of RhoA and RhoC gene expression in esophageal squamous cell carcinomaAnn Surg OncolYear: 200714359360110.1245/s10434-007-9562-x17896152
47. Simpson KJ,Dugan AS,Mercurio AM. Functional analysis of the contribution of RhoA and RhoC GTPases to invasive breast carcinomaCancer ResYear: 200464869470110.1158/0008-5472.CAN-04-224715574779
48. Bellovin DI,Simpson KJ,Danilov T,Maynard E,Rimm DL,Oettgen P,et al. Reciprocal regulation of RhoA and RhoC characterizes the EMT and identifies RhoC as a prognostic marker of colon carcinomaOncogeneYear: 20062569596710.1038/sj.onc.120968216715134
49. Iiizumi M,Bandyopadhyay S,Pai SK,Watabe M,Hirota S,Hosobe S,et al. RhoC promotes metastasis via activation of the Pyk2 pathway in prostate cancerCancer ResYear: 20086876132010.1158/0008-5472.CAN-07-670018794150
50. Philips A,Roux P,Coulon V,Bellanger JM,Vié A,Vignais ML,et al. Differential effect of Rac and Cdc42 on p38 kinase activity and cell cycle progression of nonadherent primary mouse fibroblastsJ Biol ChemYear: 20002755911710.1074/jbc.275.8.591110681583

Figures

[Figure ID: F1]

Figure 1. Cell cycle regulators and the Rho/ROCK pathway. Whereas Cyclin D1, p27, p21, and p57 collectively define the inhibitory arm of a regulatory loop linking the cell cycle to the RhoA/ROCK pathway, Cyclin A2 appears to be the first component in its activator arm.



[Figure ID: F2]

Figure 2. Cyclin A2 is at the interface between cytoplasmic and extracellular cues. When Cyclin A2 level is high, the two daughter cells orientate their bipolar mitotic spindles according to both their mother footprint and cues emanating from the lamina. If Cyclin A2 is abnormally downregulated, cell division is non-localized, cell spreading is isotropic and cells show increased motility.



Article Categories:
  • Commentary

Keywords: Keywords: RhoA, RhoC, cell polarity, centrosome, epithelium, golgi, mitotic spindle.

Previous Document:  Competing G protein-coupled receptor kinases balance G protein and ?-arrestin signaling.
Next Document:  Compression dewatering of municipal activated sludge: Effects of salt and pH.