AOYAMA, Takashi

HONMA, Takashi

KAWASHIMA, Shuichi

MURAMOTO, Takuya

OKA, Atsuhiro

SAKAI, Hiroe

YASUDA, Keiko

Kyoto University Research Information Repository

TitleNegative autoregulation of the Arabidopsis homeobox geneATHB-2 [1] / Complexes of MADS-box protein are sufficientto convert leaves into floral organs [2] / An upstream region ofthe CDC2aAt gene directs transcription during trichomedevelopment [3] (MOLECULAR BIOLOGY ANDINFORMATION - Molecular Biology)Author(s)OKA, Atsuhiro; AOYAMA, Takashi; KAWASHIMA, Shuichi;SAKAI, Hiroe; HONMA, Takashi; YASUDA, Keiko;MURAMOTO, TakuyaCitationICR annual report (2002), 8: 50-51Issue Date2002-03URL http://hdl.handle.net/2433/65307RightType ArticleTextversionpublisherKyoto UniversityICR Annual Report, Vol. 8, 200150ProfOKA, Atsuhiro(D Sc)Assoc ProfAOYAMA, Takashi(D Sc)InstrKAWASHIMA, ShuichiInstrSAKAI, Hiroe(D Sc)TechnYASUDA, KeikoPD (BRAIN)MURAMOTO, Takuya(D Sc)http://molbio.dyndns.org/Molecular Biology and Information    - Molecular Biology -StudentsLIANG, Yajie (D3, left)OHGISHI, Maki (D3, left)OHASHI, Yohei (D3)IWAKOSHI, Shintaro (M1)IMAI, Kumiko (M1)Research Activities (Year 2001)PresentationsTranscriptional networks regulated by ArabidopsisHD-Zip proteins, Aoyama T, Muramoto T, Ohgishi M,Morelli G, Ruberti I, Oka A; Target gene analysis of Ara-bidopsis ATHB-1, Muramoto T, Tukuda M, Oka A,Tabata S, Ruberti I, Morelli G, Aoyama T; Characteriza-tion of the homeobox gene, ATHB-10/GL2, Ohashi Y,Oka A, Ruberti I, Morelli G, Aoyama T, Ann Meeting ofJpn. Soc. Plant Physiol., 24-26 March (Fukuoka).Function of GL2/ATHB-10 in epidermal cellular dif-ferentiation, Ohashi Y, Oka A, Ruberti I, Morelli G,Aoyama T, 29-30 November (Tsukuba), InternationalSymposium "New era of transcription factor research inplants" organized by Takatsuji H and Aoyama T.The Arabidopsis ARR1 response regulator is a tran-scription factor for genes immediately responsive to cyto-kinins, Sakai H, Honma T, Aoyama T, Oka A;Entopically additive expression of ATHB-10/GL2 altersthe frequency and spacing of trichome initiation, OhashiY, Oka A, Ruberti I, Morelli G, Aoyama T, Ann Meetingof Mol. Biol. Soc. Jpn., 9-12 December (Yokohama).GrantsOka A, Research project for network mutually con-trolling plant responses to environmental stimuli withmorphogenesis: Hierarchy of transcriptional controls inplant signal transduction, Special Coordination Fund ofthe Ministry of Education, Culture, Sports, Science, andTechnology of Japan, 1 April 1997 - 31 March 2003Aoyama T, Functional analysis of homeodomain pro-teins controlling the flexibility of plant morphogenesis,Grant from the Bio-oriented Technology Research Ad-vancement Institution (BRAIN), 1 April 1998 - 31 March2003Aoyama T and Oka A, Molecular mechanism of adap-tive responses controlled by Arabidopsis His-Aspphosphorelay signal transduction, Grant-in-Aid for Sci-entific Research on Priority Areas (B), 1 April 2000 - 31March 2003AwardHonma T, Complexes of MADS-box proteins are suf-ficient to convert leaves into floral organs, The ICR Spe-cial Award for Young Scientists.Scope of ResearchThe major subjects are mechanisms involved in signal transduction and regulation of gene expression responsive toenvironmental stimuli, differentiation and development of plant organs, and plant-microbe interaction.  As of Decem-ber 2001, study is being concentrated on the roles of two-component response regulators and homeodomain proteins ofhigher plants in signal transduction and developmental processes.Assoc  InstrHONMA, Takashi(Deceased 14 July 2001)ICR Annual Report, Vol. 8, 2001 51Negative autoregulation of the Arabidopsishomeobox gene ATHB-2 [1]ATHB-2 is a transcription factor belonging to theArabidopsis homeodomain-leucine zipper (HD-Zip)protein family. The ATHB-2 gene is tightly regulated bylight signals, and thought to direct morphologicalchanges during shade avoidance responses. Tounderstand how ATHB-2 mediates light signals in plantmorphogenesis, we investigated its transcriptionalnetwork. We constructed a gene encoding a chimerictranscription factor (HD-Zip-2-V-G) that is expected toactivate target genes of ATHB-2 in a glucocorticoid-dependent manner. In transgenic Arabidopsis plantsexpressing HD-Zip-2-V-G, glucocorticoid treatmentactivates the ATHB-2 gene itself independently of denovo protein synthesis. An in vitro DNase I-footprintingexperiment showed that the recombinant ATHB-2protein specifically binds to an ATHB-2 promoter region.These complementary results indicate that ATHB-2recognizes its own promoter. Consistent with the fact thatATHB-2 itself has been shown to act as a repressor,expression of the endogenous ATHB-2 gene wasrepressed in transgenic plants overexpressing an ATHB-2transgene. Moreover, target-gene analyses using the HD-Zip-2-V-G suggested that ATHB-2 recognizes other HD-Zip II subfamily genes. Thus, ATHB-2 has a negativeautoregulatory loop and may be involved in acomplicated transcriptional network includingparalogous genes, like that of animal homeobox genes.1.  M. Ohgishi1, A. Oka, G. Morelli, I. Ruberti, and T. Aoyama1, PlantJ., 25, 389-398 (2001) .Complexes of MADS-box proteins are suffi-cient to convert leaves into floral organs [2]Genetic studies, using floral homeotic mutants, haveled to the ABC model of flower development. This modelproposes that the combinatorial action of three sets ofgenes, the A, B and C function genes, specify the four flo-ral organs (sepals, petals, stamens and carpels) in the con-centric floral whorls. However, attempts to convert veg-etative organs into floral organs by altering the expres-sion of ABC genes have been unsuccessful. Here weshow that the class B proteins of Arabidopsis,PISTILLATA (PI) and APETALA3 (AP3), interact withAPETALA1 (AP1, a class A protein) and SEPALLATA3(SEP3, previously AGL9), and with AGAMOUS (AG, aclass C protein) through SEP3. We also show that vegeta-tive leaves of triply transgenic plants, 35S::PI; 35S::AP3;35S::AP1 or 35S::PI; 35S::AP3; 35S::SEP3, are trans-formed into petaloid organs and that those of 35S::PI;35S::AP3; 35S::SEP3; 35S::AG are transformed intostaminoid organs. Our findings indicate that the forma-Figure 1.  Histochemical analysis of CDC2aAt promoter activity inseedlings. Transgenic Arabidopsis 5 days after germination carrying P(-1299/+677)::GUS (a), P(-591/+677)::GUS (b-d), or P(-591/+4)::GUS(e and f) were examined histochemically. Close-up pictures of apical androot meristems are shown for P(-591/+677)::GUS (c and d, respec-tively) and P(-591/+4)::GUS (f). The bars in a, b,  and e = 1 mm, and thebars in c, d and f = 0.2 mm. Quoted from ref 3.tion of ternary and quaternary complexes of ABC pro-teins may be the molecular basis of the ABC model, andthat the flower-specific expression of SEP3 restricts theaction of the ABC genes to the flower.2.  T. Honma and K. Goto, Nature, 409, 525-529 (2001).An upstream region of the CDC2aAt gene di-rects transcription during trichome develop-ment [3]Proliferation of eukaryotic cells proceeds according to acommon cell cycle program. The cell cycle is regulated attwo checkpoints at least (i.e., the G1-to-S phase transitionand entry into mitosis) through a particular class of proteinkinase activity. Since these kinases require an associatingprotein, cyclin, for their activity, they are called cyclin-de-pendent kinases (CDKs). The Arabidopsis CDC2aAt geneis thought to encode such a protein kinase, since it is ac-tively transcribed in proliferating tissues and can comple-ment defects in the Schizosaccharomyces pombe cdc2 gene.We analyzed the functional structure of the CDC2aAt pro-moter, using fusion genes between various upstream re-gions of CDC2aAt and the Escherichia coli β-glucu-ronidase (GUS) gene. A 595-base pair (bp) DNA fragmentupstream from the transcription start site conferred GUSactivity on developing trichomes, but not on proliferatingtissues. On the other hand, another upstream fragment ex-tending to the 5' non-coding transcribed region gave GUSactivity to both proliferating tissues and developing tri-chomes (Figure 1). Under the gl2 mutant background, GUSactivity directed by the 595-bp fragment was detected insingle-stalk cells, but not in giant cells without obvious po-lar extension growth. These results revealed that the 595-bpfragment lacks cis element(s) essential for proliferating-cell-specific promoter activity, but can direct transcriptionin a specific period during trichome development, whichdoesn't include cell division. These results suggests thatCDC2aAt functions during cell morphogenesis as well ascell proliferation.3.  Y. Imajuku, Y. Ohashi, T. Aoyama, K. Goto, and A. Oka, Plant Mol.Biol. 46, 205-213 (2001).

Negative autoregulation of the Arabidopsis homeobox gene ATHB-2 [1]/ Complexes of MADS-box protein are sufficient to convert leaves into floral organs [2]/ An upstream region of the CDC2aAt gene directs transcription during trichome development [3] (MOLECULAR BIOLOGY AND INFORMATION - Molecular Biology)

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Negative autoregulation of the Arabidopsis homeobox gene ATHB-2 [1] / Complexes of MADS-box protein are sufficient to convert leaves into floral organs [2] / An upstream region of the CDC2aAt gene directs transcription during trichome development [3] (MOLECULAR BIOLOGY AND INFORMATION - Molecular Biology)

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