scholarly journals Arabidopsis ASYMMETRIC LEAVES2 (AS2): roles in plant morphogenesis, cell division, and pathogenesis

2021 ◽  
Author(s):  
Yasunori Machida ◽  
Takanori Suzuki ◽  
Michiko Sasabe ◽  
Hidekazu Iwakawa ◽  
Shoko Kojima ◽  
...  
Keyword(s):  
Cell Division ◽  
Leucine Zipper ◽  
Leaf Primordia ◽  
Transcriptional Gene Silencing ◽  
Virus Infectivity ◽  
Dna Repeats ◽  
Specific Sequence ◽  
Positive Role ◽  
Cooperative Action ◽  
Amino Terminal

AbstractThe ASYMMETRIC LEAVES2 (AS2) gene in Arabidopsis thaliana is responsible for the development of flat, symmetric, and extended leaf laminae and their vein systems. AS2 protein is a member of the plant-specific AS2/LOB protein family, which includes 42 members comprising the conserved amino-terminal domain referred to as the AS2/LOB domain, and the variable carboxyl-terminal region. Among the members, AS2 has been most intensively investigated on both genetic and molecular levels. AS2 forms a complex with the myb protein AS1, and is involved in epigenetic repression of the abaxial genes ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3), ARF4, and class 1 KNOX homeobox genes. The repressed expression of these genes by AS2 is markedly enhanced by the cooperative action of various modifier genes, some of which encode nucleolar proteins. Further downstream, progression of the cell division cycle in the developing organs is stimulated; meristematic states are suppressed in determinate leaf primordia; and the extension of leaf primordia is induced. AS2 binds the specific sequence in exon 1 of ETT/ARF3 and maintains methylated CpGs in several exons of ETT/ARF3. AS2 forms bodies (designated as AS2 bodies) at nucleolar peripheries. AS2 bodies partially overlap chromocenters, including inactive 45S ribosomal DNA repeats, suggesting the presence of molecular and functional links among AS2, the 45S rDNAs, and the nucleolus to exert the repressive regulation of ETT/ARF3. The AS2/LOB domain is characterized by three subdomains, the zinc finger (ZF) motif, the internally conserved-glycine containing (ICG) region, and the leucine-zipper-like (LZL) region. Each of these subdomains is essential for the formation of AS2 bodies. ICG to LZL are required for nuclear localization, but ZF is not. LZL intrinsically has the potential to be exported to the cytoplasm. In addition to its nuclear function, it has been reported that AS2 plays a positive role in geminivirus infection: its protein BV1 stimulates the expression of AS2 and recruits AS2 to the cytoplasm, which enhances virus infectivity by suppression of cytoplasmic post transcriptional gene silencing.

Cap ‘n’ collar B cooperates with a small Maf subunit to specify pharyngeal development and suppress deformed homeotic function in the Drosophila head

Development ◽  
2000 ◽  
Vol 127 (18) ◽  
pp. 4023-4037 ◽  
Author(s):  
A. Veraksa ◽  
N. McGinnis ◽  
X. Li ◽  
J. Mohler ◽  
W. McGinnis
Keyword(s):  
Transcriptional Activation ◽  
Protein Function ◽  
Leucine Zipper ◽  
Suppressive Effect ◽  
Basic Leucine Zipper ◽  
Transcriptional Activation Domain ◽  
Amino Terminal ◽  
Culture Cells ◽  
Mandibular Segment ◽  
Direct Binding

The basic-leucine zipper protein Cap ‘n’ collar B (CncB) suppresses the segmental identity function of the Hox gene Deformed (Dfd) in the mandibular segment of Drosophila embryos. CncB is also required for proper development of intercalary, labral and mandibular structures. In this study, we provide evidence that the CncB-mediated suppression of Dfd requires the Drosophila homolog of the mammalian small Maf proteins, Maf-S, and that the suppression occurs even in the presence of high amounts of Dfd protein. Interestingly, the CncB/Maf-S suppressive effect can be partially reversed by overexpression of Homothorax (Hth), suggesting that Hth and Extradenticle proteins antagonize the effects of CncB/Maf-S on Dfd function in the mandibular segment. In embryos, multimers of simple CncB/Maf-S heterodimer sites are transcriptionally activated in response to CncB, and in tissue culture cells the amino-terminal domain of CncB acts as a strong transcriptional activation domain. There are no good matches to CncB/Maf binding consensus sites in the known elements that are activated in response to Dfd and repressed in a CncB-dependent fashion. This suggests that some of the suppressive effect of CncB/Maf-S proteins on Dfd protein function might be exerted indirectly, while some may be exerted by direct binding to as yet uncharacterized Dfd response elements. We also show that ectopic CncB is sufficient to transform ventral epidermis in the trunk into repetitive arrays of ventral pharynx. We compare the functions of CncB to those of its vertebrate and invertebrate homologs, p45 NF-E2, Nrf and Skn-1 proteins, and suggest that the pharynx selector function of CncB is highly conserved on some branches of the evolutionary tree.

Role of inverted DNA repeats in transcriptional and post-transcriptional gene silencing

2000 ◽  
pp. 123-140 ◽  
Author(s):  
Mariëlle W. M. Muskens ◽  
Adriënne P. A. Vissers ◽  
Joseph N. M. Mol ◽  
Jan M. Kooter
Keyword(s):  
Gene Silencing ◽  
Transcriptional Gene Silencing ◽  
Dna Repeats ◽  
Post Transcriptional Gene Silencing

Anatomy of Wild Garlic Bulbs During and Subsequent to After-Ripening

Weed Science ◽  
1972 ◽  
Vol 20 (3) ◽  
pp. 233-237 ◽  
Author(s):  
J. F. Stritzke ◽  
E. J. Peters
Keyword(s):  
Cell Division ◽  
Microscopic Examination ◽  
Cell Elongation ◽  
Leaf Primordia ◽  
Root Primordia ◽  
Ripening Period ◽  
Shoot Primordia ◽  
Division Cell ◽  
Wild Garlic

Microscopic examination of central and soft offset bulbs of wild garlic(Allium vinealeL.) at senescence of the parent plants in May and June revealed embryonic plants with numerous root primordia and four or five shoot primordia. Hardshell bulbs and aerial bulblets contained only one or two root primordia and three leaf primordia. The embryonic plants of central, soft offset, and hardshell bulbs elongated slowly during the after-ripening period. Rapid cell division, cell elongation, and initiation of new leaves took place after termination of the after-ripening period in all but the dormant hardshell bulbs. In November, new hardshell bulbs could be seen at the base of plants developed from central and soft offset bulbs.

scholarly journals The proto-oncogene HLF and the related basic leucine zipper protein TEF display highly similar DNA-binding and transcriptional regulatory properties

Blood ◽  
1996 ◽  
Vol 87 (11) ◽  
pp. 4607-4617 ◽  
Author(s):  
SP Hunger ◽  
S Li ◽  
MZ Fall ◽  
L Naumovski ◽  
ML Cleary
Keyword(s):  
Amino Acid ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Lymphoblastic Leukemia ◽  
Consensus Sequence ◽  
Basic Leucine Zipper ◽  
Amino Terminal ◽  
Transcriptional Regulatory ◽  
Regulatory Properties

Genes encoding transcription factors are frequently altered by chromosomal translocations in acute lymphoblastic leukemia (ALL), suggesting that aberrant transcriptional regulation plays a prominent role in leukemogenesis. E2A-hepatic leukemia factor (HLF), a chimeric transcription factor created by the t(17;19), consists of the amino terminal portion of E2A proteins, including two experimentally defined transcriptional activation domains (TADs), fused to the HLF DNA binding and protein dimerization basic leucine zipper (bZIP) domain. To understand the mechanisms by which E2A-HLF induces leukemia and the crucial functions contributed by each constituent of the chimera, it is essential to define the normal transcriptional regulatory properties of HLF and related bZIP proteins. To address these questions, we cloned the human homologue of TEF/VBP, a bZIP protein closely related to HLF. Using a binding site selection assay, we found that TEF bound preferentially to the consensus sequence 5′-GTTACGTAAT-3′, which is identical to the previously determined HLF recognition site. TEF and HLF activated transcription of consensus site-containing reporter genes in several different cell types with similar potencies. Using GAL4 chimeric proteins, a TAD was mapped to a discrete approximate 40 amino acid region of TEF and HLF within which they share 72% amino acid identity and 85% similarity. The TEF/HLF activation domain (THAD) has a predicted helical secondary structure, but shares no sequence homology with previously reported TADs. The THAD contained most, if not all, of the transcriptional activation properties present in both TEF and HLF and its deletion completely abrogated transcriptional activity of TEF and HLF in both mammalian cells and yeast. Thus, TEF and HLF share indistinguishable DNA-binding and transcriptional regulatory properties, whose alteration in leukemia may be pathogenetically important.

Heteroblastic seedlings of green ash. III. Cell division activity and marginal meristems

1986 ◽  
Vol 64 (11) ◽  
pp. 2662-2668 ◽  
Author(s):  
E. K. Merrill
Keyword(s):  
Cell Division ◽  
Leaf Blade ◽  
Developmental Stages ◽  
Leaf Primordia ◽  
Leaf Margin ◽  
Green Ash ◽  
Histological Differentiation ◽  
Cell Counts ◽  
Histological Criteria ◽  
Early Developmental

The early developmental stages of simple and compound leaves of green ash (50–400 μm long) were used to relate cell division activity (mitotic index) to developing leaf form and histological differentiation. Densely cytoplasmic cells within cross-sectioned leaf primordia have higher mitotic indices than protodermal cells and other internal cells that are more vacuolate. Among densely cytoplasmic cells mitotic indices decrease from the primordial leaf margin toward the procambium. Ground meristem cells within three to five cell widths of the primordial margin had the highest mitotic indices. Actual cell counts indicate that densely cytoplasmic cells increase in number in areas of leaf blade or leaflet initiation more than do vacuolate cells or protodermal cells. It is proposed that marginal meristems defined by spatial and histological criteria are important in producing new cells that are the basis for the generation of simple and compound leaf forms.

scholarly journals Domain swapping reveals the modular nature of Fos, Jun, and CREB proteins.

1990 ◽  
Vol 10 (9) ◽  
pp. 4565-4573 ◽  
Author(s):  
L J Ransone ◽  
P Wamsley ◽  
K L Morley ◽  
I M Verma
Keyword(s):  
Dna Binding ◽  
Protein Interactions ◽  
Leucine Zipper ◽  
Chimeric Protein ◽  
Domain Swapping ◽  
Amino Terminus ◽  
Protein Protein Interactions ◽  
Amino Terminal ◽  
Nih 3T3 ◽  
Basic Region

The products of the Jun and Fos proto-oncogenes form a heterodimer that binds to and activates transcription from 12-O-tetradecanoylphorbol-13-acetate-responsive promoter elements (TGACTCA) and AP-1-binding sites (TGACATCA). These two proteins belong to a family of related transcription factors which contain similar domains required for protein dimerization and DNA binding but display different protein and DNA binding specificities. The basic region, required for DNA binding, is followed by a leucine zipper structure, a domain that mediates protein-protein interactions. To assess the role of these two domains in three related proteins, Fos, Jun, and CREB, we carried out extensive domain-swapping analysis. We found that (i) dimers formed by two Jun leucine zipper-containing proteins were unable to bind DNA as efficiently as a Fos-Jun combination, regardless of the source of the basic region; (ii) the Fos leucine zipper was unable to form either homo- or heterodimers with a chimeric protein containing a Fos leucine zipper; (iii) the Fos basic region was capable of binding to an AP-1 site; (iv) replacement of the Jun amino terminus with that of CREB had little effect on dimerization, whereas replacement with the amino terminus of Fos disrupted both protein-protein and protein-DNA interactions; (v) changes in relative affinities of the Fos and Jun basic regions for the AP-1 element were dependent on the secondary contributions of amino-terminal residues; and (vi) the Fos-Jun chimeric constructs cooperated in transcriptional transactivation of the Jun promoter in NIH 3T3 cells.

Domain swapping reveals the modular nature of Fos, Jun, and CREB proteins

1990 ◽  
Vol 10 (9) ◽  
pp. 4565-4573
Author(s):  
L J Ransone ◽  
P Wamsley ◽  
K L Morley ◽  
I M Verma
Keyword(s):  
Dna Binding ◽  
Protein Interactions ◽  
Leucine Zipper ◽  
Chimeric Protein ◽  
Domain Swapping ◽  
Amino Terminus ◽  
Protein Protein Interactions ◽  
Amino Terminal ◽  
Nih 3T3 ◽  
Basic Region

The products of the Jun and Fos proto-oncogenes form a heterodimer that binds to and activates transcription from 12-O-tetradecanoylphorbol-13-acetate-responsive promoter elements (TGACTCA) and AP-1-binding sites (TGACATCA). These two proteins belong to a family of related transcription factors which contain similar domains required for protein dimerization and DNA binding but display different protein and DNA binding specificities. The basic region, required for DNA binding, is followed by a leucine zipper structure, a domain that mediates protein-protein interactions. To assess the role of these two domains in three related proteins, Fos, Jun, and CREB, we carried out extensive domain-swapping analysis. We found that (i) dimers formed by two Jun leucine zipper-containing proteins were unable to bind DNA as efficiently as a Fos-Jun combination, regardless of the source of the basic region; (ii) the Fos leucine zipper was unable to form either homo- or heterodimers with a chimeric protein containing a Fos leucine zipper; (iii) the Fos basic region was capable of binding to an AP-1 site; (iv) replacement of the Jun amino terminus with that of CREB had little effect on dimerization, whereas replacement with the amino terminus of Fos disrupted both protein-protein and protein-DNA interactions; (v) changes in relative affinities of the Fos and Jun basic regions for the AP-1 element were dependent on the secondary contributions of amino-terminal residues; and (vi) the Fos-Jun chimeric constructs cooperated in transcriptional transactivation of the Jun promoter in NIH 3T3 cells.

CEBPA Mutations in 4708 Patients with Acute Myeloid Leukemia - Differential Impact of bZIP and TAD Mutations on Outcome

Blood ◽  
2021 ◽  
Author(s):  
Franziska Taube ◽  
Julia Annabell Georgi ◽  
Michael Kramer ◽  
Sebastian Stasik ◽  
Jan Moritz Middeke ◽  
...  
Keyword(s):  
Leucine Zipper ◽  
Prognostic Impact ◽  
Basic Leucine Zipper ◽  
Amino Terminal ◽  
Transactivation Domains ◽  
Molecular Features ◽  
Cebpa Mutations ◽  
Biallelic Mutations ◽  
Carboxy Terminal

Biallelic mutations of the CEBPA gene (CEBPAbi) define a distinct entity associated with favorable prognosis, however the role of monoallelic mutations (CEBPAsm) is poorly understood. We retrospectively analyzed 4708 adult AML patients recruited into Study Alliance Leukemia trials to investigate the prognostic impact of CEBPAsm. CEBPA mutations were identified in 240 patients (5.1%), 131 CEBPAbi and 109 CEBPAsm (60 affecting the amino-terminal transactivation domains (CEBPAsmTAD) and 49 the carboxy-terminal DNA-binding or basic leucine zipper region (CEBPAsmbZIP)). Interestingly, CEBPAbi and CEBPAsmbZIP patients shared several clinical factors, i.e. were significantly younger (median 46 years and 50 years) and had higher WBC counts at diagnosis (median 23.7 and 35.7 109/l) compared to CEBPAsmTAD patients (median age 63 yrs., median WBC 13.1 109/l; p<.001). Co-mutations were also similar in both groups, e.g. GATA2 mutations (35.1% CEBPAbi; 36.7% CEBPAsmbZIP vs. 6.7% CEBPAsmTAD; p<.001) or NPM1 mutations (3.1% CEBPAbi; 8.2% CEBPAsmbZIP vs. 38.3% CEBPAsmTAD; p<.001). CEBPAbi and CEBPAsmbZIP, but not CEBPAsmTAD were associated with significantly improved overall (median OS: 103 and 63 vs. 13 months) and event-free survival (median EFS: 20.7 and 17.1 vs. 5.7 months), in univariate and multivariable analyses. More detailed analysis revealed that the clinical and molecular features as well as the favorable survival were confined to patients showing in-frame mutations in bZIP (CEBPAbZIP-inf). When grouping patients into CEBPAbZIP-inf and CEBPAother (including CEBPAsmTAD and other non-CEBPAbZIP-inf patients), only CEBPAbZIP-inf patients showed superior CR rates and the longest median OS and EFS, arguing for a previously undefined prognostic role of this type of mutations.

scholarly journals Tat-Binding Protein-1 (TBP-1), an ATPase of 19S Regulatory Particles of the 26S Proteasome, Enhances Androgen Receptor Function in Cooperation with TBP-1-Interacting Protein/Hop2

Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 3283-3290 ◽  
Author(s):  
Tetsurou Satoh ◽  
Takahiro Ishizuka ◽  
Takuya Tomaru ◽  
Satoshi Yoshino ◽  
Yasuyo Nakajima ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Binding Protein ◽  
26S Proteasome ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Lncap Cells ◽  
Interacting Protein ◽  
Amino Terminal

The 26S proteasome, which degrades ubiquitinated proteins, appears to contribute to the cyclical loading of androgen receptor (AR) to androgen response elements of target gene promoters; however, the mechanism whereby the 26S proteasome modulates AR recruitment remains unknown. Using yeast two-hybrid screening, we previously identified Tat-binding protein-1 (TBP-1), an adenosine triphosphatase of 19S regulatory particles of the 26S proteasome, as a transcriptional coactivator of thyroid hormone receptor. Independently, TBP-1-interacting protein (TBPIP) was also identified as a coactivator of several nuclear receptors, including AR. Here, we investigated whether TBP-1 could interact with and modulate transcriptional activation by AR cooperatively with TBPIP. TBP-1 mRNA was ubiquitously expressed in human tissues, including the testis and prostate, as well as in LNCaP cells. TBP-1 directly bound TBPIP through the amino-terminal domain possessing the leucine zipper structure. AR is physically associated with TBP-1 and TBPIP in vitro and in LNCaP cells. TBP-1 similarly and additively augmented AR-mediated transcription upon coexpression with TBPIP, and the ATPase domain, as well as leucine zipper structure in TBP-1, was essential for transcriptional enhancement. Overexpression of TBP-1 did not alter AR protein and mRNA levels. In the chromatin immunoprecipitation assay, TBP-1 was transiently recruited to the proximal androgen response element of the prostate-specific antigen gene promoter in a ligand-dependent manner in LNCaP cells. These findings suggest that a component of 19S regulatory particles directly binds AR and might participate in AR-mediated transcriptional activation in cooperation with TBPIP.

Sign in / Sign up

Export Citation Format

Share Document