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Hyeong Cheol Park, Man Lyang Kim,
Ho Soo Kim,
Jung Hoon Park,
Mi Soon Jung,
Mingzhe Shen,
Chang Ho Kang,
Min Chul Kim,
Sang Yeol Lee,
Moo Je Cho,
Woo Sik Chung,
Dae-Jin Yun
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ABSTRACT: Zinc finger-homeodomain proteins (ZF-HDs) have been identified in many plant species. In soybean (Glycine max), GmZF-HD1 functions as a transcription factor that activates the soybean calmodulin isoform-4 (GmCaM-4) gene in response to pathogens. Recently, we reported specific binding of GmZF-HD1 to a 30-nt A/T-rich cis-element which constitutes two repeats of a conserved homeodomain binding site, ATTA, within -1207 to -1128bp of the GmCaM-4 promoter. Herein, homeodomain sequences of the GmZF-HD1 protein were compared to those of other homeodomain proteins and characterized the specificity of DNA sequences in the interaction of the GmCaM-4 promoter with GmZF-HD1 protein. Considering the conservation of homeodomains in plants, the AG sequence within a 30-nt A/T-rich cis-element is required for binding of the GmZF-HD1 protein. Approximately 25-bp of A/T-rich DNA sequences containing an AG sequence is necessary for effective binding to the GmZF-HD1 protein. Taken together, the results support the notion that the GmZF-HD1 protein specifically functions in plant stress signalling by interacting with the promoter of GmCaM-4.
Phytochemistry 11/2010; 71(16):1832-8. · 3.35 Impact Factor
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Hyeong Cheol Park, Man Lyang Kim,
Yun Hwan Kang,
Jae Cheol Jeong,
Mi Sun Cheong,
Wonkyun Choi,
Sang Yeol Lee,
Moo Je Cho,
Min Chul Kim,
Woo Sik Chung,
Dae-Jin Yun
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ABSTRACT: The transcription of soybean (Glycine max) calmodulin isoform-4 (GmCaM-4) is dramatically induced within 0.5 h of exposure to pathogen or NaCl. Core cis-acting elements that regulate the expression of the GmCaM-4 gene in response to pathogen and salt stress were previously identified, between -1,207 and -1,128 bp, and between -858 and -728 bp, in the GmCaM-4 promoter. Here, we characterized the properties of the DNA-binding complexes that form at the two core cis-acting elements of the GmCaM-4 promoter in pathogen-treated nuclear extracts. We generated GUS reporter constructs harboring various deletions of approximately 1.3-kb GmCaM-4 promoter, and analyzed GUS expression in tobacco plants transformed with these constructs. The GUS expression analysis suggested that the two previously identified core regions are involved in inducing GmCaM-4 expression in the heterologous system. Finally, a transient expression assay of Arabidopsis protoplasts showed that the GmCaM-4 promoter produced greater levels of GUS activity than did the CaMV35S promoter after pathogen or NaCl treatments, suggesting that the GmCaM-4 promoter may be useful in the production of conditional gene expression systems.
Molecules and Cells 05/2009; 27(4):475-80. · 2.18 Impact Factor
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ABSTRACT: Calmodulin (CaM) is involved in defense responses in plants. In soybean (Glycine max), transcription of calmodulin isoform 4 (GmCaM4) is rapidly induced within 30 min after pathogen stimulation, but regulation of the GmCaM4 gene in response to pathogen is poorly understood. Here, we used the yeast one-hybrid system to isolate two cDNA clones encoding proteins that bind to a 30-nt A/T-rich sequence in the GmCaM4 promoter, a region that contains two repeats of a conserved homeodomain binding site, ATTA. The two proteins, GmZF-HD1 and GmZF-HD2, belong to the zinc finger homeodomain (ZF-HD) transcription factor family. Domain deletion analysis showed that a homeodomain motif can bind to the 30-nt GmCaM4 promoter sequence, whereas the two zinc finger domains cannot. Critically, the formation of super-shifted complexes by an anti-GmZF-HD1 antibody incubated with nuclear extracts from pathogen-treated cells suggests that the interaction between GmZF-HD1 and two homeodomain binding site repeats is regulated by pathogen stimulation. Finally, a transient expression assay with Arabidopsis protoplasts confirmed that GmZF-HD1 can activate the expression of GmCaM4 by specifically interacting with the two repeats. These results suggest that the GmZF-HD1 and -2 proteins function as ZF-HD transcription factors to activate GmCaM4 gene expression in response to pathogen.
Nucleic Acids Research 02/2007; 35(11):3612-23. · 8.03 Impact Factor
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ABSTRACT: Iron uptake via endocytosis of iron-transferrin-transferrin receptor complexes is a rate-limiting step for cell growth, viability and proliferation in tumor cells as well as non-transformed cells such as activated lymphocytes. Signaling pathways that regulate transferrin uptake have not yet been identified.
We surveyed the human signaling proteome for regulators that increase or decrease transferrin uptake by screening 1,804 dicer-generated signaling small interfering RNAs using automated quantitative imaging. In addition to known transport proteins, we identified 11 signaling proteins that included a striking signature set for the phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3)-target of rapamycin (mTOR) signaling pathway. We show that the PI3K-mTOR signaling pathway is a positive regulator of transferrin uptake that increases the number of transferrin receptors per endocytic vesicle without affecting endocytosis or recycling rates.
Our study identifies the PtdIns(3,4,5)P3-mTOR signaling pathway as a new regulator of iron-transferrin uptake and serves as a proof-of-concept that targeted RNA interference screens of the signaling proteome provide a powerful and unbiased approach to discover or rank signaling pathways that regulate a particular cell function.
Genome biology 02/2007; 8(7):R142. · 6.63 Impact Factor
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ABSTRACT: Many signaling, cytoskeletal, and transport proteins have to be localized to the plasma membrane (PM) in order to carry out their function. We surveyed PM-targeting mechanisms by imaging the subcellular localization of 125 fluorescent protein-conjugated Ras, Rab, Arf, and Rho proteins. Out of 48 proteins that were PM-localized, 37 contained clusters of positively charged amino acids. To test whether these polybasic clusters bind negatively charged phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] lipids, we developed a chemical phosphatase activation method to deplete PM PI(4,5)P2. Unexpectedly, proteins with polybasic clusters dissociated from the PM only when both PI(4,5)P2 and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] were depleted, arguing that both lipid second messengers jointly regulate PM targeting.
Science 01/2007; 314(5804):1458-61. · 31.20 Impact Factor
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ABSTRACT: Ca(2+) signaling in nonexcitable cells is typically initiated by receptor-triggered production of inositol-1,4,5-trisphosphate and the release of Ca(2+) from intracellular stores. An elusive signaling process senses the Ca(2+) store depletion and triggers the opening of plasma membrane Ca(2+) channels. The resulting sustained Ca(2+) signals are required for many physiological responses, such as T cell activation and differentiation. Here, we monitored receptor-triggered Ca(2+) signals in cells transfected with siRNAs against 2,304 human signaling proteins, and we identified two proteins required for Ca(2+)-store-depletion-mediated Ca(2+) influx, STIM1 and STIM2. These proteins have a single transmembrane region with a putative Ca(2+) binding domain in the lumen of the endoplasmic reticulum. Ca(2+) store depletion led to a rapid translocation of STIM1 into puncta that accumulated near the plasma membrane. Introducing a point mutation in the STIM1 Ca(2+) binding domain resulted in prelocalization of the protein in puncta, and this mutant failed to respond to store depletion. Our study suggests that STIM proteins function as Ca(2+) store sensors in the signaling pathway connecting Ca(2+) store depletion to Ca(2+) influx.
Current Biology 08/2005; 15(13):1235-41. · 9.65 Impact Factor
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Hyeong Cheol Park, Man Lyang Kim,
Yun Hwan Kang,
Joo Mi Jeon,
Jae Hyuk Yoo,
Min Chul Kim,
Chan Young Park,
Jae Cheol Jeong,
Byeong Cheol Moon,
Ju Huck Lee,
Hae Won Yoon,
Sung-Ho Lee,
Woo Sik Chung,
Chae Oh Lim,
Sang Yeol Lee,
Jong Chan Hong,
Moo Je Cho
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ABSTRACT: The Ca(2+)-binding protein calmodulin mediates cellular Ca(2+) signals in response to a wide array of stimuli in higher eukaryotes. Plants express numerous CaM isoforms. Transcription of one soybean (Glycine max) CaM isoform, SCaM-4, is dramatically induced within 30 min of pathogen or NaCl stresses. To characterize the cis-acting element(s) of this gene, we isolated an approximately 2-kb promoter sequence of the gene. Deletion analysis of the promoter revealed that a 130-bp region located between nucleotide positions -858 and -728 is required for the stressors to induce expression of SCaM-4. A hexameric DNA sequence within this region, GAAAAA (GT-1 cis-element), was identified as a core cis-acting element for the induction of the SCaM-4 gene. The GT-1 cis-element interacts with an Arabidopsis GT-1-like transcription factor, AtGT-3b, in vitro and in a yeast selection system. Transcription of AtGT-3b is also rapidly induced within 30 min after pathogen and NaCl treatment. These results suggest that an interaction between a GT-1 cis-element and a GT-1-like transcription factor plays a role in pathogen- and salt-induced SCaM-4 gene expression in both soybean and Arabidopsis.
Plant physiology 09/2004; 135(4):2150-61. · 6.53 Impact Factor
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Cha Young Kim,
Yoon Duck Koo,
Jing Bo Jin,
Byeong Cheol Moon,
Chang Ho Kang,
Sun Tae Kim,
Byung Ouk Park,
So Young Lee, Man Lyang Kim,
Inhwan Hwang,
Kyu Young Kang,
Jeong Dong Bahk,
Sang Yeol Lee,
Moo Je Cho
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ABSTRACT: Hundreds of proteins involved in signaling pathways contain a Ca(2+)-dependent membrane-binding motif called the C2-domain. However, no small C2-domain proteins consisting of a single C2-domain have been reported in animal cells. We have isolated two cDNA clones, OsERG1a and OsERG1b, that encode two small C2-domain proteins of 156 and 159 amino acids, respectively, from a fungal elicitor-treated rice cDNA library. The clones are believed to have originated from a single gene by alternative splicing. Transcript levels of the OsERG1 gene are dramatically elevated by a fungal elicitor prepared from Magnaporthe grisea or by Ca(2+) ions. The OsERG1 protein produced in Escherichia coli binds to phospholipid vesicles in a Ca(2+)-dependent manner and is translocated to the plasma membrane of plant cells by treatment with either a fungal elicitor or a Ca(2+) ionophore. These results suggest that OsERG1 proteins containing a single C2-domain are involved in plant defense signaling systems.
Biochemistry 11/2003; 42(40):11625-33. · 3.42 Impact Factor
