Journal of Nature and Science (JNSCI), Vol.1, No.4, e74, 2015

Biological Chemistry


Control of the cell cycle and mitosis by phosphorylated activating transcription factor 2 and its homologue 7 


Chia-Chen Ku1-3, Hitomi Hasegawa5,+, Chang-Shen Lin1-4, Ming-Ho Tsai1-3, Kenly Wuputra1-3, Richard Eckner6, Naoto Yamaguchi5,*, and Kazunari K. Yokoyama1-3,* 


1Center for Stem Cell Research, 2Center for Environmental Medicine, 3Graduate Institute of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan. 4Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan. 5Department of Molecular Cell Biology, Graduate School of Pharmacological Sciences, Chiba University, Chiba, Japan. 6Department of Biochemistry and Molecular Biology, Rutgers New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, USA

Activating transcription factors (ATFs) comprise a family of sequence-specific DNA-binding proteins that possess a basic region/leucine zipper (bZIP) and they play multiple roles in the mammalian cells. Despite their diverse physiological roles, they all share the ability to respond to environmental stresses and maintain cellular homeostasis. ATF2 and ATF7 are structurally very similar, especially in terms of their bZIP DNA-binding and dimerization domains, where they share >90% identity. In response to stress stimuli, ATFs activate a variety of targets, including cell cycle, DNA damage, antiproliferation, and apoptosis regulators, although most of these targets have been studied only G1/S phase events. Recent research demonstrates that the cycling-dependent kinase 1 specifically phosphorylates ATF2 and ATF7 in the M phases, and phosphorylated ATF2 and ATF7 are required for G2/M progression, partly by activating Aurora kinase. This review describes the phosphorylation mode of ATF2/ATF7 proteins and their potential functions in cell cycle progression and oncogene addiction. Journal of Nature and Science, 1(4):e74, 2015


ATF2 | ATF7 | DNA damage | G2/M progression | phosphorylation | oncogenesis transcription 



The activation transcription factor (ATF)/cAMP-response element- binding (CREB) family comprises 16 cellular stress-responsive transcription factors, which are divided into six subgroups, according to their sequence similarity (Figure 1) [1-4]. A common feature shared by all of these proteins is the basic zipper (bZIP) element, which allows them to dimerize and bind to specific DNA sequences [5-10]. The bZIP element comprises a leucine zipper subdomain and a basic region subdomain, which are connected by a short fork [11]. The bZIP transcription factors such as the ATF/cAMP-responsive-element (CRE) family and AP-1 (activation protein 1) family proteins homodimerize, but they can also selectively heterodimerize with each other, e.g., c-Fos, Fra2, and c-Jun [12, 13]. However, they share little similarity apart from the bZIP domain, and their binding sequences, such as binding to the ATF/CRE consensus 5ˊ-TGACGTC/AC/A-3ˊ [12, 14] or the AP-1 consensus 5ˊ-TGACTCA-3ˊ. Among the bZIP transcription factors, particularly the ATF/CREB and AP-1 families, ATF2, ATF7 and CREB5 comprise a similar subfamily based on their sequence conservation [5, 8, 12, 15, 16]. The transcriptional activation and DNA-binding domains of ATF2 and ATF7 are highly conserved and their specificity is governed mainly by posttranslational modifications and interactions with specific cofactors [17-20].

   The ATF2 gene is located on chromosome 2q32 and it is encoded by a 505-amino-acid protein, which is expressed ubiquitously, with more abundant expression in the brain [21, 22]. ATF2 exhibits diverse, tissue-dependent functions [23, 24]. For example, ATF2 has been implicated in malignant and non-malignant skin tumor development [25, 26]. ATF2 also elicits a suppressor functions in mammary tumors [27]. In addition, ATF2 has transcription-independent functions in the DNA damage response, chromatin remodeling, and mitochondrial membrane organization.

The ATF7 gene is located on chromosome 12q13 and it encodes a 483-amino-acid protein, which is also expressed ubiquitously. Depending on the cellular context, the composition of the dimeric complex determines the regulation of growth, survival, and apoptosis. ATF7 is known to share similarity with TATA-binding protein associated proteins (TAFs) such as TAF 4 [19]. ATF7 is also critical for neuron networks and social stress-related responses [28]. These multiple functions of ATF2 and ATF7 in oncogenesis and mammalian development are related mainly posttranslational regulation including phosphorylation.

   This short review summarizes our current understanding of the phosphorylation status of ATF2 and ATF7 during the cell cycle and the possible functions of phosphorylated ATF2 and ATF7.


Figure 1. Schematic representation of members of the ATF/CREB transcription factor family. ATF/CREB protein members can be categorized into six subgroups according to their sequence similarity. The red boxes indicate the bZIP domain. (GenBank Accession numbers: AAC60616, Q02930, AAC02258, P18848, AAD51372, and AAB49921). The figure is modified as reported previously (Ref. 24, Figure 2).


Complex isoforms of ATF2 and ATF7

ATF2 has several splice variants, including mouse orthologues (CRE-BP1, CRE-BP2, and CRE-BP-3) and one human isoform (ATFs-sm). The structures of CRE-BP1 and CRE-BP3 are nearly identical, except that eight hydrophobic amino acids in CRE-BP3 replace the first 15 amino acids in CRE-BP1 [29]. By contrast, CRE-BP2 has a 98-amino-acid N-terminal internal deletion. The splice variants of these three murine isoforms occur predominantly in the N- and extreme C-termini, whereas the bZIP domain is conserved, thereby suggesting that the transcription factor function of these variants is conserved, although their regulation might differ due to the loss of various regulatory elements in the N-termini [21, 29]. In agreement with this hypothesis, CRE-BP3 and CRE-BP1 exhibit only weak or no transcriptional activity in murine T cells, respectively, whereas CRE-BP2 exhibits strong transcriptional activity. The human ATF2 splice isoform ATF2-sm lacks the entire bZIP domain and it only retains the first and the last two exons of the full-length ATF2. However, despite the absence of the bZIP domain, ATF2-sm still exhibits its transcriptional activity [30]. ATF2-sm is specifically expressed in endometrial tissue and its protein levels fluctuate dynamically throughout pregnancy [30]. This distinct expression pattern suggests that ATF2 splice variants might elicit tissue- and temporal-specific functions, which may be distinct from those regulated by the full-length ATF2 [31].

In the case of ATF7, three major different transcripts are encoded in humans. i.e., ATF7-1, ATF7-2, and ATF7-4, whereas only one, ATF7-2, is encoded in the mouse [32, 33]. The ATF7-4 protein contains the common ATF7 N-terminal moiety (88 residues), which encompasses the transcriptional activation domain [34], but it lacks the entire C-terminal bZIP domain (residues 89–494), and the DNA binding/nuclear localization signal, and a dimerization domain. The ATF7-4 isoform is potentially encoded in many mammalian genomes, but not in the mouse and rat, and it is localized mainly in the cytoplasm [33]. The human ATF2 and human ATF7 genes generate 13 and six transcripts variants, respectively, including noncoding RNA. In order to prepare specific ATF2 and ATF7 short hairpin (sh) knockdown constructs, the care should be taken when selecting the corresponding sequences, as they might present splice variants or noncoding transcripts. 


Specificity of antibodies against ATF2 and ATF7

Hasegawa et al. (2014) reported a problem with reagents such as antibodies against ATF2 and ATF7 [35]. Surprisingly, most of the widely used ATF2 antibodies such as N-96 (sc-63233; Santa Cruz Biotechnology Inc.) and phopsho-ATF2 (pT71) (#922; Cell Signaling Technology) can cross-react with ATF7. Thus, most previous studies that used these antibodies also analyzed the ATF7 protein. It is possible to differentiate ATF2 and ATF7 proteins using antibodies from Sigma-Aldrich Co. ATF2 [ss-16] is specific for ATF2 (#A4086; Sigma-Aldrich) and anti-ATF7 antibodies (#SAB250013 and #HPA003384; Sigma-Aldrich) are specific for ATF7. Thus, we consider that the critical observation might lead to re-investigation of previously obtained results.


Role of ATF2 in human cancer 

Analyses of tumor samples in breast cancer and melanoma suggest that ATF2 may possess tumor suppressive and promoting functions, respectively [27, 36]. Furthermore, the enhanced presence of activated (Thr71 phosphorylated) ATF2 has been reported in common types of skin carcinoma, e.g., squamous cell carcinoma, Bowen’s disease, and basal cell carcinoma, thereby suggesting the involvement of ATF2 in this type of tumor [37]. However, activation does not preclude a functional role for ATF2 in the development of this type of tumor, and thus further experimental testing is required. Interestingly, a recent global genomic analysis identified a comprehensive array of gene mutations and the core signaling pathways instrumental in pancreatic cancer development [38]. This study confirmed that mutations in Kras and associated genes are major features of pancreatic tumors. In addition, significant numbers of gene mutations have been identified in MAPK (Jun Nh2-terminal protein kinase; JNK) components as well as in ATF2 protein in cancer specimens. This may suggest that JNK signaling and/or ATF2 are instrumental in the progression of this cancer type, but this remains to be examined experimentally. ATF2 mutations have also been identified in mammary carcinomas (see Catalogue of Somatic Mutations in Cancer at Therefore, it is still unclear whether the mutations identified in cancer cell lines have any significant effects on the function of ATF2 s well as on the tumor phenotype.


Loss of function of ATF2 and ATF7 in mouse models

Reimold et al. (1996) reported that the first Atf2 mouse knockout led to decreased postnatal viability and reduced growth in animals, as well as defects in endochondral ossification and in the central nervous system [39]. However, this knockout was subsequently shown to be hypomorphic because it retained some of the ATF2 activity due to alternative splicing in the targeted allele [40]. Another knockout of ATF2 (Atf20/0) was generated by the deletion of the DNA-binding domain, which produced, at least transcrip- tionally, a functional null mutation. All of the Atf20/0 mutant mice died shortly after birth because of severe respiratory distress [40]. Furthermore, Maekawa et al. demonstrated that a knock-in mutant mouse line where the Thr69 and Thr71 (Thr51 and Thr53 in mouse ATF2) phosphorylation sites in the transcription activation domain were mutated into alanine (Atf2AA) yielded to a similar phenotype, and to invariably led to death at birth, thereby confirming the importance of these phosphorylation sites for the activity of ATF2 [41]. Ackermann et al. (2011) demonstrated that the perinatal death caused by the loss of ATF2 functions in mouse embryos is probably caused by defects during the development of the brainstem, where ATF2 is involved in functions that prevent specific sets of facial motor neurons from undergoing neuro- degeneration and apoptosis. Previous studies of the deletion of the DNA-binding domain of ATF7 in the presence of functional ATF2 have not identified exposed any discernible developmental phenotypes in mice [41]. However, ATF7 has an important role in the adult central nervous system, specifically in the regulation of gene expression in dorsal raphe nuclei of the brainstem in response to isolation stress. By contrast, the ATF2/ATF7 double deletion (Atf2/; Atf7/) results in severe hypoplasia in the embryonic heart and liver, thereby leading to lethality between embryonic days 11.5 and 12.5 [41]. This demonstrates that these two transcription factors share essential functions during embryonic development. Interestingly, the embryonic liver defect is very similar to that caused by deletion of the JNK-activating kinase MKK4 (MAPK kinase 4) [43, 44] and it occurs around the same time, but significantly before the liver defect observed in c-Jun-knockout embryos [45, 46], which suggests that ATF2 and ATF7 are essential substrates for embryonic JNK signaling. ATF2/ATF7 mutant liver progenitor cells (hepatoblasts) undergo high rates of apoptosis in embryos as well as in culture. This high rate of apoptosis in cultured hepatoblasts can be rescued by the chemical inhibition of p38 activity, which suggests that these transcription factors may be involved in negative-feedback regulation of their upstream activating kinases. Double mutant livers express reduced levels of specific MAPK phosphatases, including Dusp1, Dusp8 and Dusp10, which are direct targets for ATF2/ATF7- mediated transcription.


Figure 2. Phosphorylation of ATF2 protein and ATF7 protein. Schematic representation of various kinases that can phosphorylate ATF2 protein. The model designated as (Cell cycle) was modified (33). Most of the phosphorylation sites are shown during the G1/S phase. Hasegawa et al. (35) reported the cdk1–cycling B complex was phosphorylated in the G2/M phase.


Posttranslational regulation of ATF2 and ATF7 

ATF-2 is phosphorylated by many upstream kinases including stress-activating kinase or protein kinase C (PKC) in the G1/S phase (Figure 2). JNK, p38, and Erk, which are activated by stress stimuli, phosphorylate ATF2 at Thr-69 and Thr-71 (Thr-69/Thr-71) and lead to its transcriptional activation [47-52]. Moreover, the phosphorylation of ATF2 at Ser-121 by several PKC isoforms (including α, βI, βII, and γ) plays a role in the c-Jun-mediated activation of transcription in response to 12-O-tetradecanoylphorbol-13-acetate [53]. It is known that ATF7 is phosphorylated by p38 at Thr-51 and Thr-53, which correspond to Thr-69 and Thr-71 in ATF2, thereby leading to its transcriptional activation [54, 55]. In contrast to its transcriptional functions, ATF2 has several functions that are independent of transcriptional activation [56]. ATF2 is phosphorylated at Thr-52 by PKCε, which negatively regulates the outer-membrane permeability of mitochondria and inhibits apoptosis during genotoxic stress [57]. During the DNA damage response, ataxia telangiectasia mutated (ATM) phosphorylates ATF2 at Ser-490 and Ser-498, to facilitate DNA repair [58]. In this context, the interaction between ATF2 and the histone acetyltransferase TIP60 comprises a positive feedback loop, which allows ATF2 to promote the activity of ATM. Genotoxic stress attenuates the interaction between TIP60 and ATF2, which stabilizes TIP60 and promotes the subsequent acetylation and activation of ATM [59]. Thus, ATF2 and ATF7 play important roles in the G1 and S phases.

Recently, Hasegawa et al. (2014) identified a new kinase that phosphorylates ATF2 and ATF7 in the G2 and M phases [35]. ATF2 (at Thr-69/Thr-71) and ATF7 (at Thr-51/Thr-53) are phosphorylated by cyclin-dependent kinase 1 (Cdk1) in the M phase. Similar to the knockdown of ATF7, the expression of mitotically nonphosphorylatable ATF7 inhibits the entry of cells into the M phase [35]. These results suggest that the phosphorylation of ATF7 at Thr-51/Thr-53 during the M phase plays an important role in G2/M progression, partly by activating Auora kinases.

ATF-2 is also acetylated on Lys-357 and Lys-374 by p300 or CREB-binding protein (CBP, also known as CREBBP), which contributes to its transcriptional activity [60]. The binding of ATF2 suppresses the acetyltransferase activity of the transcriptional coactivator p300/CBP. The cross-regulation between the acetylation and phosphorylation of ATF2 has yet to be elucidated in the context of its transcriptional activities.

The stability of ATF2 protein is regulated by ubiquitylation and SUMOylation. However, the exact model has not been elucidated in detail. N-terminal phosphorylation and heterodimerization of ATF2 reduce its transcriptional activity by promoting ubiquitylation-dependent degradation [61]. The binding of JNK to ATF2 serves to limit the availability of ATF2 by promoting its degradation, but the E3 ubiquitin ligases involved in the ubiquitylation and degradation of ATF2 have not been identified. The SUMO-conjugating enzyme Ubc9 has been shown to interact with ATF2 and to affect its stability [62], although ATF2 SUMOylation has not been demonstrated formally.  


Interplay between mitochondria and nuclear ATF2

Although the phosphorylation of ATF2 by PKCε is a key determinant of its subcellular localization and function, the precise mechanism underlying its nuclear export and localization to the mitochondria has yet to be determined. PKCε functions as an addicting signal to maintain the nuclear localization of ATF2, which prevents its pro-apoptotic function in the mitochondria. Thus, provides that the activity of PKCε activity is sustained, ATF2 will exhibit oncogenic functions within the nucleus. This interplay might be a critical regulatory effect of ATF2/ATF7 transcription factors.


ATF7 phosphorylation is linked to Aurora signaling

Hasegawa et al. (2014) showed that the mitotic phosphorylation of ATF7 is involved in Aurora signaling [35]. The Aurora family comprises three members; Aurora A, B, and C. Aurora A is an oncogene in a variety of cancers and it plays a role in centrosome maturation during the function the G2/M transition [63]. Disruption of the function of Aurora A delays mitotic entry [64, 65]. Inhibition of Aurora kinases is also known to induce apoptosis [66], so the downregulation of Aurora kinase signaling by ATF7 knockdown may explain the increased apoptosis during the sub-G1 phase after the G2/M-phase arrest following ATF7 knockdown.

Inhibition of the kinase activity of Cdk1 induces Aurora A inactivation, although Cdk1 does not directly phosphorylate Aurora A [67]. Activated Aurora B phosphorylates histone H3 at Ser-10 [68-71]. However, after Cdk1 is activated, the mitotic phosphorylation of ATF7 precedes the phosphorylation of histone H3 at Ser-10, which suggests that ATF7 is located upstream of the Aurora kinases. Thus, it is assumed that the mitotic phosphorylation of ATF7 by the Cdk1–cyclin B1 complex promotes the activation of Aurora kinases to allow mitotic entry via the stabilization of Aurora kinases (see Figure 3).


Figure 3. Possible roles of ATF2 and ATF7 phosphorylation in G2/M progression. During the late stages of the G2 and M phases, Thr-51/Thr-53 in ATF7 and Thr-69/Thr-71 in ATF2 are phosphorylated by cdk1–cyclin B1, which promotes M-phase entry by stabilizing Aurora kinase family.


Potential functions of ATF2/ATF7 function in cell division 

It is well known that the correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division [72]. The main aim of mitosis is ensuring that the replicated sister chromatids are segregated with the highest possible accuracy among the daughter cells. In principal, this is a mechanical problem related to the generation of a force that segregates the two sister chromatids of each chromosome and moves them to opposite ends of the cell division plane. The mitotic spindle provides a platform that facilitates the accurate alignment of the condensed chromosomes and it comprises a molecular machine that segregates the sister chromatids [73]. It is essential that the segregation process is only initiated when each chromosome is aligned in the center of the spindle and bi-oriented, so the sister chromatids in each network are subjected to various checkpoints to ensure the accuracy of this timing [74]. The Aurora kinases play a major role in orchestrating bipolar spindle establishment, chromosome alignment, and segregation. Aurora A is involved in the centrosome dynamics, and Aurora B coordinates kinetochore attachment and cytokinesis. Aurora C is functionally related to Aurora B and it is thought to play a role in the meiotic cell cycle, although it does not appear to be essential for cell division in somatic cells. The coordination of Aurora kinases may involve the following three mechanisms: (1) kinetic proofreading of CenpE related to microtubule (MT) attachment by Aurora kinases, (2) regulation of Kif18B/MCAK by Aurora kinases, and (3) regulation of the anaphases MT dynamics by Aurora kinases. According to the first model, the phosphorylation of CenpE by Aurora kinases results in kinetic proofreading [75]. Aurora kinases destablize destabilizes CenpE binding to MTs because the protein is more likely to re-attach to a neighboring MT in the dense kinetochore MT fiber (K-fiber) bundles than are single astral MTs. In the second model, the Kif18b/MCAK interaction is controlled by Aurora kinases [76]. The plus-ended motor Kif18b transports MCAK to the MT tip, where it depolymerizes the tubulin polymers. Aurora kinases negatively regulate this interaction jointly via an unknown mechanism. In the third model, Aurora kinases control MT depolymerization during anaphase [77]. In metaphase, the kinetochores are attached to kinetochore K-fibers, which reach to the spindle poles. Minus-end depolymerization causes a constant flux of tubulin toward the spindle poles, which is counteracted by plus-end MT polymerization at the kinetochore to achieve a constant spindle length. During anaphase, the K-fibers are rapidly depolymerized at both the plus and minus ends. This MT depolymerization releases energy, which is used to pull the kinetochores along the shrinking K-fiber. Possible targets in this pathway are proteins that regulate MT stability. In particular, the end-binding proteins have been shown to increase ploidy 1 (lgl1) substrates in yeast, and this phosphorylation is linked to spindle disassembly [77]. However, it is unclear how phosphorylated ATF2 and ATF7 might control the activity of Aurora kinase during the progression of mitosis. 

The proteasome is also known to function at the onset of mitosis [78, 79]. Thus, Hesegawa et al. (2014) examined the role of ATF7 in M-phase progression in ATF7-wt- or ATF7-TA-inducible cells using the proteasome inhibitor MG132 at the onset of mitosis, which showed that the proteosomal control of inhibitor proteins or associated proteins was induced by phosphorylated ATF2/ATF7 and the M-phase then proceeded smoothly [35]. Thus, it is hypothesized that the mitotic phosphorylation of ATF7 promotes Aurora signaling at the onset of M phase in a manner that is dependent on the activity of the proteasome. Although no physical associations have been detected between ATF7, phosphorylated Aurora kinases, and its related proteins, it is of interest to determine precisely how the mitotic phosphorylation of ATF7 is involved in Aurora signaling, specifically the stability of Aurora kinase, which allows to the active dividing machinery, such as histone H3 phosphorylation, to promote cell division. 

Future studies will reveal the roles of this novel mechanism of ATF2/ATF7 during mitosis progression in cell growth control, transformation, and cancer development.


Future perspectives

ATF2 and ATF7 are known to be important as transcription factors, DNA-damage response proteins and during G2/M progression, but they also implicated in the regulation of cellular growth and cell division control. ATF2 and ATF7 have functions in checkpoint control during the intra-S phase and probably in mitosis, as well as in transcriptional regulation via distinct upstream regulatory kinases. It is still necessary to clarify whether different pools of ATF2 and ATF7 are utilized for each of these functions, and whether their roles in the DNA repair axis affects the transcriptional activities of ATF2 and ATF7. Novel functions of ATF2 and ATF7 during G2/M progression might control Aurora signaling in cell division. Our growing understanding of the complex regulatory roles of ATF2 and ATF7 indicates that they may have the capacity to elicit oncogenes or anti-oncogenic function, as well as being involved in mitotic regulation.



We thank Drs. O Lee, K Kato, K Nagata, S Lin, YC, G Gachelin and M. Horikoshi for their advice and discussions. This study was supported by grants from the Taiwan government: NSC-101-2320-B-037-047-My3; NSC-103-2314-B-037-063; NHRI-Ex102-10109BI; NHRI-EX104-10416SI; KMU-DT103001; KMU-TP103G00, KMU-TP103G03, KMU-TP103G04, KMU-TP103G05, KMU-TP103A04.


1.      HPescini RH, HKaszubska WH, HWhelan JH, HDeLamarter JFH,& HHooft van Huijsduijnen RH. ATF-a0, a novel variant of the ATF/CREB transcription factor family, forms a dominant transcription inhibitor in ATF-a heterodimers. HJ.H Biol. Chem. 1994; 269: 1159-1165.

2.      Hai T & Hartman MG. HThe molecular biology and nomenclature of the activating transcription factor/cAMP responsive element binding family of transcription factors: activating transcription factor proteins and homeostasis.H Gene 2001; 273: 1-11.

3.      HHaze KH, HOkada TH, HYoshida HH, HYanagi HH, HYura TH, HNegishi MH, & HMori KH. Identification of the G13 (cAMP-response-element-binding protein-related protein) gene product related to activating transcription factor 6 as a transcriptional activator of the mammalian unfolded protein response. Biochem. J. 2001; 355: 19-28.

4.      HWang JH, HCao YH, & HSteiner DFH. Regulation of proglucagon transcription by activated transcription factor (ATF) 3 and a novel isoform, ATF3b, through the cAMP-response element/ATF site of the proglucagon gene promoter. J. Biol. Chem. 2003; 278: 32899-32904.

5.      HGaire MH, HChatton BH, & HKedinger CH. Isolation and characterization of two novel, closely related ATF cDNA clones from HeLa cells. HNuc. Acids Res.H 1990; 18: 3467-3473.

6.      HLiu FH, HThompson MAH, HWagner SH, HGreenberg MEH, & HGreen MRH.Activating transcription factor-1 can mediate Ca(2+)- and cAMP-inducible transcriptional activation. J. Biol. Chem.1993; 268: 6714-6720.

7.      HMasquilier DH, HFoulkes NSH, HMattei MGH, & HSassone-Corsi PH. Human CREM gene: evolutionary conservation, chromosomal localization, and inducibility of the transcript. HCell Growth DifferentiationH 1993; 4: 931-937.

8.      HNomura NH, HZu YLH, HMaekawa TH, HTabata SH, HAkiyama TH, & HIshii SH. Isolation and characterization of a novel member of the gene family encoding the cAMP response element-binding protein CRE-BP1. HJ. Biol. Chem. 1993; H268: 4259-4266.

9.      HDorsey MJH, HTae HJH, HSollenberger KGH, HMascarenhas NTH, & HJohansen LMH, B-ATF: a novel human bZIP protein that associates with members of the AP-1 transcription factor family. HOncogeneH 1995; 11: 2255-2265.

10.  HForgacs EH, HGupta SKH, HKerry JAH, & HSemmes OJH. The bZIP transcription factor ATFx binds human T-cell leukemia virus type 1 (HTLV-1) Tax and represses HTLV-1 long terminal repeat-mediated transcription. J. Virol. 2005; 79: 6932-6939.

11.  HLandschulz WHH, HJohnson PFH, & HMcKnight SLH. The leucine zipper: a hypothetical structure common to a new class of DNA binding proteins. HScienceH 1988; 240: 1759-1764.

12.  HHai TWH, HLiu FH, HCoukos WJH, & HGreen MRH. Transcription factor ATF cDNA clones: an extensive family of leucine zipper proteins able to selectively form DNA-binding heterodimers. HGenes Dev.H 1989; 12: 2083-2090.

13.  HVinson CRH, HHai TH, & HBoyd SMH. Dimerization specificity of the leucine zipper-containing bZIP motif on DNA binding: prediction and rational design. Genes DevH.H 1993; 7: 1047-1058.

14.  HLin YSH, & HGreen MRH. Interaction of a common cellular transcription factor, ATF, with regulatory elements in both E1a- and cyclic AMP-inducible promoters. HProc. Natl. Acad. Sci. USA H1988; 85: 3396-3400.

15.  HLee KAH, HFink JSH, HGoodman RHH, & HGreen MRH. Distinguishable promoter elements are involved in transcriptional activation by E1a and cyclic AMP. See comment in PubMed Commons belowHMol. Cell. Biol.H 1989: 9: 4390-4397.

16.  HMaekawa TH, HSakura HH, HKanei-Ishii CH, HSudo TH, HYoshimura TH, HFujisawa JH, HYoshida MH, & HIshii SH. Leucine zipper structure of the protein CRE-BP1 binding to the cyclic AMP response element in brain. HEMBO J.H 1989; 8: 2023-2038.

17.  HDe Graeve FH, HBahr AH, HChatton BH, & HKedinger CH. A murine ATFa-associated factor with transcriptional repressing activity. HOncogeneH 2000; 19: 1807-1819.

18.  HDuyndam MCH1, Hvan Dam HH, HSmits PHH, HVerlaan MH, Hvan der Eb AJH, & HZantema AH. The N-terminal transactivation domain of ATF2 is a target for the co-operative activation of the c-jun promoter by p300 and 12S E1A. HOncogeneH 1999; 18: 2311-2321.

19.  HHamard PJH, HDalbies-Tran RH, HHauss CH, HDavidson IH, HKedinger CH, & HChatton BH. A functional interaction between ATF7 and TAF12 that is modulated by TAF4. HOncogeneH 2005; 24: 3472-3483.

20.  HHong SH, HChoi HMH, HPark MJH, HKim YHH, HChoi YHH, HKim HHH, HChoi YHH, & HCheong JH. Activation and interaction of ATF2 with the coactivator ASC-2 are responsive for granulocytic differentiation by retinoic acid. HJ Biol. Chem.H 2004; 279: 16996-167003.

21.  HKara CJH, HLiou HCH, HIvashkiv LBH, & HGlimcher LHH. A cDNA for a human cyclic AMP response element-binding protein which is distinct from CREB and expressed preferentially in brain. HMol. Cell. Biol.H 1990; 10: 1347-1357.

22.  HTakeda JH, HMaekawa TH, HSudo TH, HSeino YH, HImura HH, HSaito NH, HTanaka CH, & HIshii SH. Expression of the CRE-BP1 transcriptional regulator binding to the cyclic AMP response element in central nervous system, regenerating liver, and human tumors. HOncogeneH 1991; 6: 1009-1014. 

23.  HBhoumik AH, HLopez-Bergami PH, HRonai ZH. ATF2 on the double-activating transcription factor and DNA damage response protein. HPigment Cell Res.H 2007; 20498-20506.

24.  HVlahopoulos SAH, HLogotheti SH, HMikas DH, HGiarika AH, HGorgoulis VH, & HZoumpourlis VH. The role of ATF-2 in oncogenesis. HBioessaysH 2008; 30: 314-327.

25.  HBhoumik AH, HGangi LH, & HRonai ZH. Inhibition of melanoma growth and metastasis by ATF2-derived peptides. HCancer Res.H 2004; 64: 8222-8230.

26.  HBhoumik AH, HFichtman BH, HDerossi CH, HBreitwieser WH, HKluger HMH, HDavis SH, HSubtil AH, HMeltzer PH, HKrajewski SH, HJones NH, & HRonai ZH. Suppressor role of activating transcription factor 2 (ATF2) in skin cancer. HProc. Natl. Acad. Sci. USAH 2008; 105: 1674-1679.

27.  HMaekawa TH, HShinagawa TH, HSano YH, HSakuma TH, HNomura SH, HNagasaki KH, HMiki YH, HSaito-Ohara FH, HInazawa JH, HKohno TH, HYokota JH, & HIshii SH. Reduced levels of ATF-2 predispose mice to mammary tumors. HMolecular Cellular BiolHogy 2007; 27:1730-1744.

28.  HMaekawa TH, HKim SH, HNakai DH, HMakino CH, HTakagi TH, HOgura HH, HYamada KH, HChatton BH, & HIshii SH. Social isolation stress induces ATF-7 phosphorylation and impairs silencing of the 5-HT 5B receptor gene. HEMBO J.H 2010; 29: 196-208.

29.  HGeorgopoulos KH, HMorgan BAH, & HMoore DDH. Functionally distinct isoforms of the CRE-BP DNA-binding protein mediate activity of a T-cell-specific enhancer. HMol. Cell. Biol.H 1992; 12:747-757.

30.  HBailey JH, HPhillips RJH, HPollard AJH, HGilmore KH, HRobson SCH, & HEurope-Finner GNH. Characterization and functional analysis of cAMP response element modulator protein and activating transcription factor 2 (ATF2) isoforms in the human myometrium during pregnancy and labor: identification of a novel ATF2 species with potent transactivation properties. See comment in PubMed Commons below HJ. Clin.Endocrinol Metab.H 2002; 87:1717-1728.

31.  Bailey J, & Europe-Finner GN. HIdentification of human myometrial target genes of the c-Jun NH2-terminal kinase (JNK) pathway: the role of activating transcription factor 2 (ATF2) and a novel spliced isoform ATF2-small.H J. Mol. Endocrinol. 2005; 34:19-35.

32.  HGoetz JH, HChatton BH, HMattei MGH, & HKedinger CH. Structure and expression of the ATFa gene. HJ. Biol. Chem.H 1996; 271: 29589-29598.

33.  HDiring JH, HCamuzeaux BH, HDonzeau MH, HVigneron MH, HRosa-Calatrava MH, HKedinger CH, & HChatton BH. A cytoplasmic negative regulator isoform of ATF7 impairs ATF7 and ATF2 phosphorylation and transcriptional activity. HPLoS One.H 2011; 6: e23351.

34.  HChatton BH, HBocco JLH, HGoetz JH, HGaire MH, HLutz YH, & HKedinger CH. Jun and Fos heterodimerize with ATFa, a member of the ATF/CREB family and modulate its transcriptional activity. See comment in PubMed Commons below HOncogene.H 1994; 9: 375-385.

35.  HHasegawa HH, HIshibashi KH, HKubota SH, HYamaguchi CH, HYuki RH, HNakajo HH, HEckner RH, HYamaguchi NH, HYokoyama KKH, & HYamaguchi NH. Cdk1-Mediated Phosphorylation of Human ATF7 at Thr-51 and Thr-53 Promotes Cell-Cycle Progression into M Phase. HPLoS One.H 2014; 9: e116048.

36.  HBerger AJH, HKluger HMH, HLi NH, HKielhorn EH, HHalaban RH, HRonai ZH, & HRimm DLH. Subcellular localization of activating transcription factor 2 in melanoma specimens predicts patient survival. HCancer Res.H 2003; 63: 8103-8107.

37.  HChen SYH, HTakeuchi SH, HUrabe KH, HHayashida SH, HKido MH, HTomoeda HH, HUchi HH, HDainichi TH, HTakahara MH, HShibata SH, HTu YTH, HFurue MH, & HMoroi YH. Overexpression of phosphorylated-ATF2 and STAT3 in cutaneous angiosarcoma and pyogenic granuloma. HJ Cutan Pathol.H 2008; 35:722-730.

38.  HJones SH, HZhang XH, HParsons DWH, HLin JCH, HLeary RJH, HAngenendt PH, HMankoo PH, HCarter HH, HKamiyama HH, HJimeno AH, HHong SMH, HFu BH, HLin MTH, HCalhoun ESH, HKamiyama MH, HWalter KH, HNikolskaya TH, HNikolsky YH, HHartigan JH, HSmith DRH, HHidalgo MH, HLeach SDH, HKlein APH, HJaffee EMH, HGoggins MH, HMaitra AH, HIacobuzio-Donahue CH, HEshleman JRH, HKern SEH, HHruban RHH, HKarchin RH, HPapadopoulos NH, HParmigiani GH, HVogelstein BH, HVelculescu VEH, & HKinzler KWH. Core signaling pathways in human pancreatic cancers revealed by global genomic analyses. HScience.H 2008; 321: 1801-1806.

39.  HReimold AMH, HGrusby MJH, HKosaras BH, HFries JWH, HMori RH, HManiwa SH, HClauss IMH, HCollins TH, HSidman RLH, HGlimcher MJH, & HGlimcher LHH. Chondrodysplasia and neurological abnormalities in ATF-2-deficient mice. Nature. 1996; 279: 262-265.

40.  HMaekawa TH, HBernier FH, HSato MH, HNomura SH, HSingh MH, HInoue YH, HTokunaga TH, HImai HH, HYokoyama MH, HReimold AH, HGlimcher LHH, & HIshii SH. Mouse ATF-2 null mutants display features of a severe type of meconium aspiration syndrome. HJ Biol Chem.H 1999; 274: 17813-9.

41.  HBreitwieser WH, HLyons SH, HFlenniken AMH, HAshton GH, HBruder GH, HWillington MH, HLacaud GH, HKouskoff VH, & HJones NH. Feedback regulation of p38 activity via ATF2 is essential for survival of embryonic liver cells. HGenes Dev.H 2007; 21: 2069-82.

42.  HAckermann JH, HAshton GH, HLyons SH, HJames DH, HHornung JPH, HJones NH, & HBreitwieser WH. Loss of ATF2 function leads to cranial motoneuron degeneration during embryonic mouse development. HPLoS OneH 2011; 6: e19090.

43.  HGaniatsas SH, HKwee LH, HFujiwara YH, HPerkins AH, HIkeda TH, HLabow MAH, & HZon LIH. SEK1 deficiency reveals mitogen-activated protein kinase cascade crossregulation and leads to abnormal hepatogenesis. HProc. Natl. Acad. Sci. U S AH 1998; 95:6881-6886.

44.  HNishina HH, HVaz CH, HBillia PH, HNghiem MH, HSasaki TH, HDe la Pompa JLH, HFurlonger KH, HPaige CH, HHui CH, HFischer KDH, HKishimoto HH, HIwatsubo TH, HKatada TH, HWoodgett JRH, & HPenninger JMH. Defective liver formation and liver cell apoptosis in mice lacking the stress signaling kinase SEK1/MKK4. HDevelopmentH 1999; 126: 505-516.

45.  HHilberg FH, HAguzzi AH, HHowells NH, & HWagner EFH. c-jun is essential for normal mouse development and hepatogenesis. HNatureH 1993; 365: 179-181.

46.  HJohnson RSH, Hvan Lingen BH, HPapaioannou VEH, & HSpiegelman BMH. A null mutation at the c-jun locus causes embryonic lethality and retarded cell growth in culture. HGenes Dev.H 1993; 7: 1309-1317.

47.  HGupta SH, HCampbell DH, HDérijard BH, & HDavis RJH. Transcription factor ATF2 regulation by the JNK signal transduction pathway. HSee comment in PubMed Commons belowHHScienceH 1995; 267: 389-393.

48.  Hvan Dam HH, HWilhelm DH, HHerr IH, HSteffen AH, HHerrlich PH, & HAngel PH. ATF-2 is preferentially activated by stress-activated protein kinases to mediate c-jun induction in response to genotoxic agents. HEMBO J.H 1995; 14: 1798-1811.

49.  HLivingstone CH, HPatel GH, & HJones NH. ATF-2 contains a phosphorylation-dependent transcriptional activation domain. HEMBO J.H 1995; 14: 1785-1797.

50.  HOuwens DMH, Hde Ruiter NDH, Hvan der Zon GCH, HCarter APH, HSchouten JH, Hvan der Burgt CH, HKooistra KH, HBos JLH, HMaassen JAH, & Hvan Dam HH. Growth factors can activate ATF2 via a two-step mechanism: phosphorylation of Thr71 through the Ras-MEK-ERK pathway and of Thr69 through RalGDS-Src-p38. HEMBO J.H 2002; 21: 3782-3793.

51.  HMorton SH, HDavis RJH, & HCohen PH. Signalling pathways involved in multisite phosphorylation of the transcription factor ATF-2. HFEBS Lett.H 2004; 572: 177-83.

52.  HLopez-Bergami PH, HLau EH, & HRonai ZH. Emerging roles of ATF2 and the dynamic AP1 network in cancer. HNat. Rev. Cancer.H 2010; 10: 65-76.

53.  HYamasaki TH, HTakahashi AH, HPan JH, HYamaguchi NH, & HYokoyama KKH. Phosphorylation of Activation Transcription Factor-2 at Serine 121 by Protein Kinase C Controls c-Jun-mediated Activation of Transcription. HJ. Biol. Chem.H 2009; 284: 8567-8581.

54.  HCamuzeaux BH, HDiring JH, HHamard PJH, HOulad-Abdelghani MH, HDonzeau MH, HVigneron MH, HKedinger CH, & HChatton BH. p38beta2-mediated phosphorylation and sumoylation of ATF7 are mutually exclusive. HJ. Mol. Biol.H 2008; 384: 980-991.

55.  HGozdecka MH, & HBreitwieser WH. The roles of ATF2 (activating transcription factor 2) in tumorigenesis. HBiochem Soc Trans.H 2012; 40: 230-234. 

56.  HLau EH, & HRonai ZAH. ATF2-at the crossroad of nuclear and cytosolic functions. HJ. Cell Sci.H 2012; 125: 2815-2824.

57.  HLau EH, HKluger HH, HVarsano TH, HLee KH, HScheffler IH, HRimm DLH, HIdeker TH, & HRonai ZAH. PKCε promotes oncogenic functions of ATF2 in the nucleus while blocking its apoptotic function at mitochondria. HCell H2012; 148: 543-555.

58.  HBhoumik AH, HLopez-Bergami PH, & HRonai ZH. ATF2 on the double-activating transcription factor and DNA damage response protein. HPigment Cell Res.H 2007; 20: 498-506.

59.  HBhoumik AH, HSingha NH, HO'Connell MJH, & HRonai ZAH. Regulation of TIP60 by ATF2 modulates ATM activation. HJ. Biol. Chem.H 2008; 283: 17605-17614.

60.  HKaranam BH, HWang LH, HWang DH, HLiu XH, HMarmorstein RH, HCotter RH, & HCole PAH. Multiple roles for acetylation in the interaction of p300 HAT with ATF-2. HBiochemistryH 2007; 46: 8207-8216.

61.  HFuchs SYH, & HRonai ZH. Ubiquitination and degradation of ATF2 are dimerization dependent. HMol. Cell. Biol.H 1999; 19: 3289-3298.

62.  HFirestein RH, & HFeuerstein NH. Association of activating transcription factor 2 (ATF2) with the ubiquitin-conjugating enzyme hUBC9. Implication of the ubiquitin/proteasome pathway in regulation of ATF2 in T cells. HJ. Biol. Chem.H 1998; 273: 5892-5902.

63.  HBarr ARH, & HGergely FH. Aurora-A: the maker and breaker of spindle poles. HJ. Cell Sci.H 2007; 120: 2987-2996.

64.  HMarumoto TH, HHonda SH, HHara TH, HNitta MH, HHirota TH, HKohmura EH, & HSaya HH. Aurora-A kinase maintains the fidelity of early and late mitotic events in HeLa cells. HJ. Biol. Chem.H 2003; 278: 51786-51795.

65.  HHirota TH, HKunitoku NH, HSasayama TH, HMarumoto TH, HZhang DH, HNitta MH, HHatakeyama KH, & HSaya HH. Aurora-A and an interacting activator, the LIM protein Ajuba, are required for mitotic commitment in human cells. HCellH 2003; 114: 585-598.

66.  HPérez de Castro IH, Hde Cárcer GH, HMontoya GH, & HMalumbres MH. Emerging cancer therapeutic opportunities by inhibiting mitotic kinases. Curr. Opin. Pharnmacol. 2008; 8: 375-383.

67.  HMarumoto TH, HHirota TH, HMorisaki TH, HKunitoku NH, HZhang DH, HIchikawa YH, HSasayama TH, HKuninaka SH, HMimori TH, HTamaki NH, HKimura MH, HOkano YH, & HSaya HH. Roles of aurora-A kinase in mitotic entry and G2 checkpoint in mammalian cells. HGenes Cells H2002; 7:1173-1182.

68.  HHsu JYH, HSun ZWH, HLi XH, HReuben MH, HTatchell KH, HBishop DKH, HGrushcow JMH, HBrame CJH, HCaldwell JAH, HHunt DFH, HLin RH, HSmith MMH, & HAllis CDH. Mitotic phosphorylation of histone H3 is governed by Ipl1/aurora kinase and Glc7/PP1 phosphatase in budding yeast and nematodes. HCellH 2000; 102: 279-291.

69.  HCrosio CH, HFimia GMH, HLoury RH, HKimura MH, HOkano YH, HZhou HH, HSen SH, HAllis CDH, & HSassone-Corsi PH. Mitotic phosphorylation of histone H3: spatio-temporal regulation by mammalian Aurora kinases. HMol. Cell. Biol.H 2002; 22: 874-885.

70.  HRuchaud SH, HCarmena MH, & HEarnshaw WCH. Chromosomal passengers: conducting cell division. HNat. Rev. Mol. Cell. Biol.H 2007; 8: 798-812.

71.  Giet R, & Glover DM. Drosophila aurora B kinase is required for histone H3 phosphorylation and condensin recruitment during chromosome condensation and to organize the central spindle during cytokinesis. J. Cell. Biol. 2001; 152: 669-682.

72.  HKops GJH, HWeaver BAH, & HCleveland DWH. On the road to cancer: aneuploidy and the mitotic checkpoint. HNat Rev Cancer.H 2005; 5: 773-785.

73.  HMaiato HH, & HLince-Faria MH. The perpetual movements of anaphase. HCell. Mol. Life Sci.H 2010; 67: 2251-2269.

74.  HSullivan MH, & HMorgan DOH. Finishing mitosis, one step at a time. HNat. Rev. Mol. Cell. Biol.H 2007; 8: 894-903.  

75.  HKapoor TMH, HLampson MAH, HHergert PH, HCameron LH, HCimini DH, HSalmon EDH, HMcEwen BFH, & HKhodjakov AH. Chromosomes can congress to the metaphase plate before biorientation. HScience.H 2006; 311: 388-391.

76.  HTanenbaum MEH, HMacurek LH, Hvan der Vaart BH, HGalli MH, HAkhmanova AH, & HMedema RHH. A complex of Kif18b and MCAK promotes microtubule depolymerization and is negatively regulated by Aurora kinases. HCurr. Biol.H 2011; 21: 1356-1365.

77.  HHégarat NH, HSmith EH, HNayak GH, HTakeda SH, HEyers PAH, & HHochegger HH. Aurora A and Aurora B jointly coordinate chromosome segregation and anaphase microtubule dynamics. HJ. Cell Biol.H 2011; 195:1103-1113.

78.  HAcquaviva CH, & HPines JH. The anaphase-promoting complex/cyclosome: APC/C. HJ. Cell Sci.H 2006; 119:2401-2404.

79.  HBassermann FH, HEichner RH, & HPagano MH. The ubiquitin proteasome system- implications for cell cycle control and the targeted treatment of cancer. HBiochim. Biophys. Acta.H 2014; 1843: 150-162.


Conflict of interest: No conflicts declared.

+Present address; Education & Research Center for Pharmaceutical Sciences, Faculty of Pharma Sciences, Teikyo University, Tokyo, Japan

*Corresponding Authors: Naoto Yamaguchi (, and Kazunari K. yokoyama (

© 2015 by the Journal of Nature and Science (JNSCI).