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Xin Y, Tan C, Wang C, Wu Y, Huang S, Gao Y, Wang L, Wang N, Liu Z, Feng H. BrAN contributes to leafy head formation by regulating leaf width in Chinese cabbage ( Brassica rapa L. ssp. pekinensis). HORTICULTURE RESEARCH 2022; 9:uhac167. [PMID: 36204207 PMCID: PMC9531340 DOI: 10.1093/hr/uhac167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 07/18/2022] [Indexed: 06/16/2023]
Abstract
Leafy head is an important agronomic trait that determines the yield and quality of Chinese cabbage. The molecular mechanism underlying heading in Chinese cabbage has been the focus of research, and wide leaves are a prerequisite for leafy head formation. In our study, two allelic leafy heading-deficient mutants (lhd1 and lhd2) with narrow leaf phenotypes were screened in an ethyl methanesulfonate mutagenized population from a heading Chinese cabbage double haploid line 'FT'. Genetic analysis revealed that the mutant trait was controlled by a recessive nuclear gene, which was found to be BraA10g000480.3C by MutMap and Kompetitive allele-specific PCR analyses. As BraA10g000480.3C was the ortholog of ANGUSTIFOLIA in Arabidopsis, which has been found to regulate leaf width by controlling cortical microtubule arrangement and pavement cell shape, we named it BrAN. BrAN in mutant lhd1 carried an SNP (G to A) on intron 2 that co-segregated with the mutant phenotype, and disrupted the exon-intron splice junction generating intron retention and a putative truncated protein. BrAN in mutant lhd2 carried an SNP (G to A) on exon 4 leading to a premature stop codon. The ectopic overexpression of BrAN restored normal leaf phenotype due to abnormal cortical microtubule arrangement and pavement cell shape in the Arabidopsis an-t1 mutant. However, transformation of Bran did not rescue the an-t1 phenotype. These results indicate that BrAN contributes to leafy head formation of Chinese cabbage.
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Affiliation(s)
| | | | - Che Wang
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang 110866, China
| | - Yanji Wu
- Liaoning Key Laboratory of Genetics and Breeding for Cruciferous Vegetable Crops, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Shengnan Huang
- Liaoning Key Laboratory of Genetics and Breeding for Cruciferous Vegetable Crops, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Yue Gao
- Liaoning Key Laboratory of Genetics and Breeding for Cruciferous Vegetable Crops, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang 110866, China
| | - Lu Wang
- Liaoning Key Laboratory of Genetics and Breeding for Cruciferous Vegetable Crops, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Nan Wang
- Liaoning Key Laboratory of Genetics and Breeding for Cruciferous Vegetable Crops, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Zhiyong Liu
- Liaoning Key Laboratory of Genetics and Breeding for Cruciferous Vegetable Crops, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
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Takechi K, Nagase H, Furuya T, Hattori K, Sato Y, Miyajima K, Higuchi T, Matsuda R, Takio S, Tsukaya H, Takano H. Two atypical ANGUSTIFOLIA without a plant-specific C-terminus regulate gametophore and sporophyte shapes in the moss Physcomitrium (Physcomitrella) patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:1390-1399. [PMID: 33280196 DOI: 10.1111/tpj.15121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 11/06/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
ANGUSTIFOLIA (AN) is a plant-specific subfamily of the CtBP/BARS/AN family, characterized by a plant-specific C-terminal domain of approximately 200 amino acids. Previously, we revealed that double knockout (DKO) lines of Physcomitrium (Physcomitrella) patens ANGUSTIFOLIA genes (PpAN1-1 and PpAN1-2) show defects in gametophore height and the lengths of the seta and foot region of sporophytes, by reduced cell elongation. In addition to two canonical ANs, the genome of P. patens has two atypical ANs without a coding region for a plant-specific C-terminus (PpAN2-1 and PpAN2-2); these were investigated in this study. Similar to PpAN1s, both promoters of the PpAN2 genes were highly active in the stems of haploid gametophores and in the middle-to-basal region of young diploid sporophytes that develop into the seta and foot. Analyses of PpAN2-1/2-2 DKO and PpAN quadruple knockout (QKO) lines implied that these four AN genes have partially redundant functions to regulate cell elongation in their expression regions. Transgenic strains harboring P. patens α-tubulin fused to green fluorescent protein, which were generated from a QKO line, showed that the orientation of the microtubules in the gametophore tips in the PpAN QKO lines was unchanged from the wild-type and PpAN1-1/1-2 DKO plants. In addition to both PpAN2-1 and PpAN2-2, short Arabidopsis AN without the C-terminus of 200 amino acids could rescue the Arabidopsis thaliana an-1 phenotypes, implying AN activity is dependent on the N-terminal regions.
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Affiliation(s)
- Katsuaki Takechi
- Faculty of Advanced Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Hiroaki Nagase
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Tomoyuki Furuya
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Koro Hattori
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - Yoshikatsu Sato
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, 464-8601, Japan
| | - Kensuke Miyajima
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Tomofumi Higuchi
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Ryuya Matsuda
- Center for Water Cycle, Marine Environment and Disaster Management, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Susumu Takio
- Faculty of Advanced Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
- Center for Water Cycle, Marine Environment and Disaster Management, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Hirokazu Tsukaya
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - Hiroyoshi Takano
- Faculty of Advanced Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
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Hashida Y, Takechi K, Abiru T, Yabe N, Nagase H, Hattori K, Takio S, Sato Y, Hasebe M, Tsukaya H, Takano H. Two ANGUSTIFOLIA genes regulate gametophore and sporophyte development in Physcomitrella patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:1318-1330. [PMID: 31674691 DOI: 10.1111/tpj.14592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 08/06/2019] [Accepted: 10/17/2019] [Indexed: 05/08/2023]
Abstract
In Arabidopsis thaliana the ANGUSTIFOLIA (AN) gene regulates the width of leaves by controlling the diffuse growth of leaf cells in the medio-lateral direction. In the genome of the moss Physcomitrella patens, we found two normal ANs (PpAN1-1 and 1-2). Both PpAN1 genes complemented the A. thaliana an-1 mutant phenotypes. An analysis of spatiotemporal promoter activity of each PpAN1 gene, using transgenic lines that contained each PpAN1-promoter- uidA (GUS) gene, showed that both promoters are mainly active in the stems of haploid gametophores and in the middle to basal region of the young sporophyte that develops into the seta and foot. Analyses of the knockout lines for PpAN1-1 and PpAN1-2 genes suggested that these genes have partially redundant functions and regulate gametophore height by controlling diffuse cell growth in gametophore stems. In addition, the seta and foot were shorter and thicker in diploid sporophytes, suggesting that cell elongation was reduced in the longitudinal direction, whereas no defects were detected in tip-growing protonemata. These results indicate that both PpAN1 genes in P. patens function in diffuse growth of the haploid and diploid generations but not in tip growth. To visualize microtubule distribution in gametophore cells of P. patens, transformed lines expressing P. patens α-tubulin fused to sGFP were generated. Contrary to expectations, the orientation of microtubules in the tips of gametophores in the PpAN1-1/1-2 double-knockout lines was unchanged. The relationships among diffuse cell growth, cortical microtubules and AN proteins are discussed.
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Affiliation(s)
- Yoshikazu Hashida
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Katsuaki Takechi
- Faculty of Advanced Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Tomomi Abiru
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Noriyuki Yabe
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Hiroaki Nagase
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Koro Hattori
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - Susumu Takio
- Faculty of Advanced Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
- Center for Water Cycle, Marine Environment and Disaster Management, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
| | - Yoshikatsu Sato
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, 464-8601, Japan
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology and SOKENDAI (Graduate School for Advanced Studies), Okazaki, 444-8585, Japan
| | - Hirokazu Tsukaya
- Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - Hiroyoshi Takano
- Faculty of Advanced Science and Technology, Kumamoto University, Kurokami, Kumamoto, 860-8555, Japan
- Institute of Pulsed Power Science, Kumamoto University, Kumamoto, 860-8555, Japan
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Furuya T, Hattori K, Kimori Y, Ishida S, Nishihama R, Kohchi T, Tsukaya H. ANGUSTIFOLIA contributes to the regulation of three-dimensional morphogenesis in the liverwort Marchantia polymorpha. Development 2018; 145:dev.161398. [PMID: 30126903 DOI: 10.1242/dev.161398] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 08/06/2018] [Indexed: 01/04/2023]
Abstract
Arabidopsis thaliana mutants deficient in ANGUSTIFOLIA (AN) exhibit several phenotypes at the sporophyte stage, such as narrow and thicker leaves, trichomes with two branches, and twisted fruits. It is thought that these phenotypes are caused by abnormal arrangement of cortical microtubules (MTs). AN homologs are present in the genomes of diverse land plants, including the basal land plant Marchantia polymorpha, and their molecular functions have been shown to be evolutionarily conserved in terms of the ability to complement the A. thaliana an-1 mutation. However, the roles of ANs in bryophytes, the life cycle of which includes a dominant haploid gametophyte generation, remain unknown. Here, we have examined the roles of AN homologs in the model bryophyte M. polymorpha (MpAN). Mpan knockout mutants showed abnormal twisted thalli and suppressed thallus growth along the growth axis. Under weak blue light conditions, elongated thallus growth was observed in wild-type plants, whereas it was suppressed in the mutants. Moreover, disordered cortical MT orientations were observed. Our findings suggest that MpAN contributes to three-dimensional morphogenesis by regulating cortical MT arrangement in the gametophytes of bryophytes.
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Affiliation(s)
- Tomoyuki Furuya
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Koro Hattori
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Yoshitaka Kimori
- Department of Imaging Science, Center for Novel Science Initiatives, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
| | - Sakiko Ishida
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Ryuichi Nishihama
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Hirokazu Tsukaya
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan .,Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
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Bhasin H, Hülskamp M. ANGUSTIFOLIA, a Plant Homolog of CtBP/BARS Localizes to Stress Granules and Regulates Their Formation. FRONTIERS IN PLANT SCIENCE 2017; 8:1004. [PMID: 28659951 PMCID: PMC5469197 DOI: 10.3389/fpls.2017.01004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 05/26/2017] [Indexed: 05/12/2023]
Abstract
The ANGUSTIFOLIA (AN) gene in Arabidopsis is important for a plethora of morphological phenotypes. Recently, AN was also reported to be involved in responses to biotic and abiotic stresses. It encodes a homolog of the animal C-terminal binding proteins (CtBPs). In contrast to animal CtBPs, AN does not appear to function as a transcriptional co-repressor and instead functions outside nucleus where it might be involved in Golgi-associated membrane trafficking. In this study, we report a novel and unexplored role of AN as a component of stress granules (SGs). Interaction studies identified several RNA binding proteins that are associated with AN. AN co-localizes with several messenger ribonucleoprotein granule markers to SGs in a stress dependent manner. an mutants exhibit an altered SG formation. We provide evidence that the NAD(H) binding domain of AN is relevant in this context as proteins carrying mutations in this domain localize to a much higher degree to SGs and strongly reduce AN dimerization and its interaction with one interactor but not the others. Finally, we show that AN is a negative regulator of salt and osmotic stress responses in Arabidopsis suggesting a functional relevance in SGs.
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Gachomo EW, Jimenez-Lopez JC, Smith SR, Cooksey AB, Oghoghomeh OM, Johnson N, Baba-Moussa L, Kotchoni SO. The cell morphogenesis ANGUSTIFOLIA (AN) gene, a plant homolog of CtBP/BARS, is involved in abiotic and biotic stress response in higher plants. BMC PLANT BIOLOGY 2013; 13:79. [PMID: 23672620 PMCID: PMC3663690 DOI: 10.1186/1471-2229-13-79] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 05/10/2013] [Indexed: 05/03/2023]
Abstract
BACKGROUND ANGUSTIFOLIA (AN), one of the CtBP family proteins, plays a major role in microtubule-dependent cell morphogenesis. Microarray analysis of mammalian AN homologs suggests that AN might function as a transcriptional activator and regulator of a wide range of genes. Genetic characterization of AN mutants suggests that AN might be involved in multiple biological processes beyond cell morphology regulation. RESULTS Using a reverse genetic approach, we provide in this paper the genetic, biochemical, and physiological evidence for ANGUSTIFOLIA's role in other new biological functions such as abiotic and biotic stress response in higher plants. The T-DNA knockout an-t1 mutant exhibits not only all the phenotypes of previously described angustifolia null mutants, but also copes better than wild type under dehydration and pathogen attack. The stress tolerance is accompanied by a steady-state modulation of cellular H(2)O(2) content, malondialdehyde (MDA) derived from cellular lipid peroxidation, and over-expression of stress responsive genes. Our results indicate that ANGUSTIFOLIA functions beyond cell morphology control through direct or indirect functional protein interaction networks mediating other biological processes such as drought and pathogen attacks. CONCLUSIONS Our results indicate that the ANGUSTIFOLIA gene participates in several biochemical pathways controlling cell morphogenesis, abiotic, and biotic stress responses in higher plants. Our results suggest that the in vivo function of plant ANGUSTIFOLIA has been overlooked and it needs to be further studied beyond microtubule-dependent cell morphogenesis.
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Affiliation(s)
- Emma W Gachomo
- Department of Biology, Rutgers University, 315 Penn St, Camden, NJ 08102, USA
- Center for Computational and Integrative Biology, 315 Penn St, Camden, NJ 08102, USA
| | - Jose C Jimenez-Lopez
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, Granada E-18008, Spain
| | - Sarah R Smith
- Department of Biology, Rutgers University, 315 Penn St, Camden, NJ 08102, USA
| | - Anthony B Cooksey
- Department of Biology, Rutgers University, 315 Penn St, Camden, NJ 08102, USA
| | - Oteri M Oghoghomeh
- Department of Biology, Rutgers University, 315 Penn St, Camden, NJ 08102, USA
| | - Nicholas Johnson
- Department of Biology, Rutgers University, 315 Penn St, Camden, NJ 08102, USA
| | | | - Simeon O Kotchoni
- Department of Biology, Rutgers University, 315 Penn St, Camden, NJ 08102, USA
- Center for Computational and Integrative Biology, 315 Penn St, Camden, NJ 08102, USA
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Minamisawa N, Sato M, Cho KH, Ueno H, Takechi K, Kajikawa M, Yamato KT, Ohyama K, Toyooka K, Kim GT, Horiguchi G, Takano H, Ueda T, Tsukaya H. ANGUSTIFOLIA, a plant homolog of CtBP/BARS, functions outside the nucleus. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 68:788-99. [PMID: 21801251 DOI: 10.1111/j.1365-313x.2011.04731.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
CtBP/BARS is a unique protein family in having quite diversified cellular functions, intercellular localizations, and developmental roles. ANGUSTIFOLIA (AN) is the sole homolog of CtBP/BARS from Arabidopsis thaliana, although it has plant AN-specific motifs and a long C-terminus. Previous studies suggested that AN would function in the nucleus as a transcriptional co-repressor, as CtBPs function in animals; however, precise verification has been lacking. In this paper, we isolated a homologous gene (MAN) of AN from liverwort, Marchantia polymorpha. Transformation of the Arabidopsis an-1 mutant with 35S-driven MAN completely complemented the an-1 phenotype, although it lacks the putative nuclear localization signal (NLS) that exists in AN proteins isolated from other plant species. We constructed several plasmids for expressing modified ANs with amino acid substitutions in known motifs. The results clearly indicated that modified AN with mutations in the putative NLS-like domain could complement the an-1 phenotype. Therefore, we re-examined localization of AN using several techniques. Our results demonstrated that AN localizes on punctuate structures around the Golgi, partially overlapping with a trans-Golgi network resident, which highlighted an unexpected link between leaf development and membrane trafficking. We should reconsider the roles and evolutionary traits of AN based on these findings.
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Affiliation(s)
- Naoko Minamisawa
- Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
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Lin X, Minamisawa N, Takechi K, Zhang W, Sato H, Takio S, Tsukaya H, Takano H. Isolation and characterization of the Larix gmelinii ANGUSTIFOLIA (LgAN) gene. PLANTA 2008; 228:601-8. [PMID: 18560884 DOI: 10.1007/s00425-008-0762-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 05/19/2008] [Indexed: 05/03/2023]
Abstract
ANGUSTIFOLIA (AN), a plant homolog of C-terminal binding protein, controls the polar elongation of leaf cells and the trichome-branching pattern in Arabidopsis thaliana. In the present study, degenerate PCR was used to isolate an ortholog of AN, referred to as LgAN, from larch (Larix gmelinii). The LgAN cDNA is predicted to encode a protein of 646 amino acids that shows striking sequence similarity to AN proteins from other plants. The predicted amino acid sequence has a conserved NAD-dependent 2-hydroxy acid dehydrogenase (D2-HDH) motif and a plant AN-specific LxCxE/D motif at its N-terminus, as well as a plant-specific long C-terminal region. The LgAN gene is a single-copy gene that is expressed in all larch tissues. Expression of the LgAN cDNA rescued the leaf width and trichome-branching pattern defects in the angustifolia-1 (an-1) mutant of Arabidopsis, showing that the LgAN gene has effects complementary to those of AN. These results suggest that the LgAN gene has the same function as the AN gene.
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Affiliation(s)
- Xiaofei Lin
- Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto, 860-8555 Japan.
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The Caenorhabditis elegans Protein CTBP-1 Defines a New Group of THAP Domain-Containing CtBP Corepressors. J Mol Biol 2008; 375:1-11. [DOI: 10.1016/j.jmb.2007.10.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 10/09/2007] [Accepted: 10/16/2007] [Indexed: 11/20/2022]
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Structurally related Arabidopsis ANGUSTIFOLIA is functionally distinct from the transcriptional corepressor CtBP. Dev Genes Evol 2007; 217:759-69. [PMID: 17972097 DOI: 10.1007/s00427-007-0186-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 09/18/2007] [Indexed: 10/22/2022]
Abstract
ANGUSTIFOLIA (AN) controls leaf morphology in the plant Arabidopsis thaliana. Previous studies on sequence similarity demonstrated that the closest proteins to AN are members of animal C-terminal-binding proteins (CtBPs) found in nematodes, arthropods, and vertebrates. Drosophila CtBP (dCtBP) functions as a transcriptional corepressor for deoxyribonucleic acid (DNA)-binding repressors containing the short amino acid motif, PXDLS, to regulate tissue specification and segmentation during early embryogenesis. It has previously been shown that AN was thought to repress transcription similar to the function of CtBPs; however, AN lacks some of the structural features that are conserved in animal CtBPs. In this paper, we examined whether AN is functionally related to dCtBP. Firstly, we re-examined sequence similarity among AN and various CtBPs from several representative species in the plant and animal kingdoms. Secondly, yeast two-hybrid assays demonstrated that AN failed to interact with an authentic CtBP-interacting factor, adenovirus E1A oncoprotein bearing the PXDLS motif. Thirdly, AN tethered to DNA was unable to repress the expression of reporter genes in transgenic Drosophila embryos. Fourthly, overexpression assays suggested that dCtBP and AN function differently in Drosophila tissues. Finally, AN failed to rescue the zygotic lethality caused by dCtBP loss-of-function. These data, taken together, suggest that AN is functionally distinct from dCtBP. Likely, ancestral CtBPs acquired corepressor function (capability of both repression and binding to repressors containing the PXDLS motif) after the animal-plant divergence but before the protostome-deuterostome split. We therefore propose to categorize AN as a subfamily member within the CtBP/BARS/RIBEYE/AN superfamily.
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Abstract
Biodiversity of plant shape is mainly attributable to biodiversity of leaf shape and the shape of floral organs, the modified leaves. However, the exact mechanisms of leaf-shape determination remain unclear due to the complexity of flat-structure organogenesis that includes the simultaneous cell cycling and cell enlargement in primordia. Recent studies in developmental and molecular genetics have revealed several important aspects of leaf-shape control mechanisms. For example, understanding of polar control in leaf-blade expansion has advanced greatly. A curious phenomenon called "compensated cell enlargement" found in leaf organogenesis studies should also provide interesting clues regarding the mechanisms of multicellular organ development. This paper reviews recent research findings with a focus on leaf development in Arabidopsis thaliana.
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Affiliation(s)
- Hirokazu Tsukaya
- Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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