• Molecules and Cells
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• 제28권5호
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• pp.455-461
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• 2009

Calcineurin is a $Ca^{2+}$/Calmodulin activated Ser/Thr phosphatase that is well conserved from yeast to human. It is composed of catalytic subunit A (CnA) and regulatory subunit B (CnB). C. elegans homolog of CnA and CnB has been annotated to tax-6 and cnb-1, respectively and in vivo function of both genes has been intensively studied. In C. elegans, calcineurin play roles in various signaling pathways such as fertility, movement, body size regulation and serotonin-mediated egg laying. In order to understand additional signaling pathway(s) in which calcineurin functions, we screened for binding proteins of TAX-6 and found a novel binding protein, HLH-11. The HLH-11, a member of basic helix-loop-helix (bHLH) proteins, is a putative counterpart of human AP4 transcription factor. Previously bHLH transcription factors have been implicated to regulate many developmental processes such as cell proliferation and differentiation, sex determination and myogenesis. However, the in vivo function of hlh-11 is largely unknown. Here, we show that hlh-11 is expressed in pharynx, intestine, nerve cords, anal depressor and vuvla muscles where calcineurin is also expressed. Mutant analyses reveal that hlh-11 may have role(s) in regulating body size and reproduction. More interestingly, genetic epistasis suggests that hlh-11 may function to regulate serotoninmediated egg laying at the downstream of tax-6.

• Molecules and Cells
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• 제19권3호
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• pp.334-341
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• 2005

Plants are sessile and rely on a wide variety of growth hormones to adjust growth and development in response to internal and external stimuli. We have identified a gene, designated NAN, encoding a basic helix-loop-helix (bHLH) transcription factor that regulates cell elongation and seed germination in plants. NAN has an HLH motif in its C-terminal region but does not have any other discernible homologies to bHLH proteins. A bipartite nuclear localization signal is located close to the HLH motif. An Arabidopsis mutant, nan-1D, in which NAN is activated by the insertion of the 35S enhancer, exhibits growth retardation with short hypocotyls and curled leaves. It is also characterized by reduced seed germination and apical hook formation, symptomatic of GA deficiency or disrupted GA signaling. The phenotypic effects of nan-1D were increased by treatment with paclobutrazol (PAC), an inhibitor of gibberellic acid (GA) biosynthesis. NAN is constitutively expressed throughout the life cycle. Our observations indicate that NAN has a housekeeping role in plant growth and development, particularly in seed germination and cell elongation, and that it may modulate GA signaling.

• BMB Reports
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• 제32권1호
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• pp.45-50
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• 1999

We previously found three transcription factor-binding motifs in the rat p53 promoter. They are two recognition motifs of NF1-like protein (NF1-like element 1: -296 ~ -312, NF1-like element 2: -195 ~ -219) and a bHLH protein binding element (-142 ~ -146). In this study, we investigated the DNA-protein complex formation of the three elements with nuclear extracts from both normal and regenerating liver to find the element involved in the induced transcription of p53. The level of each DNA-protein complex on NF1-like and bHLH motifs was not changed. Instead, a new element located at -264 ~ -284 was detected in the DNase I footprinting assay with regenerating nuclear extract. This element has partial homology to the AP1 consensus motif. However, the competition studies with diverse oligonucleotides suggest that the binding protein is not AP1. An in vitro transcription assay shows that this element is important for the transcriptional activation of the rat p53 promoter. Therefore, for the induced transcription of the rat p53 promoter, the-264 ~ -284 region is required in addition to two NF1-like and one bHLH motif.

• Molecules and Cells
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• 제40권6호
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• pp.426-433
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• 2017

Ephrin-A5 has been implicated in the regulation of brain morphogenesis and axon pathfinding. In this study, we used bacterial homologous recombination to express a LacZ reporter in various ephrin-A5 BAC clones to identify elements that regulate ephrin-A5 gene expression during mesencephalon development. We found that there is mesencephalon-specific enhancer activity localized to a specific +25.0 kb to +30.5 kb genomic region in the first intron of ephrin-A5. Further comparative genomic analysis indicated that two evolutionary conserved regions, ECR1 and ECR2, were present within this 5.5 kb region. Deletion of ECR1 from the enhancer resulted in disrupted mesencephalon-specific enhancer activity in transgenic embryos. We also found a consensus binding site for basic helix-loop-helix (bHLH) transcription factors (TFs) in a highly conserved region at the 3'-end of ECR1. We further demonstrated that specific deletion of the bHLH TF binding site abrogated the mesencephalon-specific enhancer activity in transgenic embryos. Finally, both electrophoretic mobility shift assay and luciferase-based transactivation assay revealed that the transcription factor Ascl1 bound the bHLH consensus binding site in the mesencephalon-specific ephrin-A5 enhancer in vitro. Together, these results suggest that the bHLH TF binding site in ECR1 is involved in the positive regulation of ephrin-A5 gene expression during the development of the mesencephalon.

• BMB Reports
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• 제30권3호
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• pp.205-210
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• 1997

p53 tumor suppressor plays an important role in the regulation of cellular proliferation. To identify proteins regulating the expression of p53 in rat liver, we analyzed p53 promoter by electrophoretic mobility shift assay (EMSA) and DNase I footprinting assay. We found that a protein binds the sequence CACGTG, bHLH consensus sequence in rat p53 promoter. Southwestern blotting analysis with oligonucleotides containing this sequence shows that the molecular weight of the protein is 100 kDa. This size is not compatible with the bHLH family such as USF or c-Myc/Max which is known to regulate the expression of the human and mouse p53 gene. Therefore this 100 kDa protein may be a new protein regulating basal transcription of rat p53. We purified this 100 kDa protein through sequence-specific DNA affinity chromatogaphy.

• Molecules and Cells
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• 제44권5호
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• pp.342-355
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• 2021

The microphthalmia-associated transcription factor family (MiT family) proteins are evolutionarily conserved transcription factors that perform many essential biological functions. In mammals, the MiT family consists of MITF (microphthalmia-associated transcription factor or melanocyte-inducing transcription factor), TFEB (transcription factor EB), TFE3 (transcription factor E3), and TFEC (transcription factor EC). These transcriptional factors belong to the basic helix-loop-helix-leucine zipper (bHLH-LZ) transcription factor family and bind the E-box DNA motifs in the promoter regions of target genes to enhance transcription. The best studied functions of MiT proteins include lysosome biogenesis and autophagy induction. In addition, they modulate cellular metabolism, mitochondria dynamics, and various stress responses. The control of nuclear localization via phosphorylation and dephosphorylation serves as the primary regulatory mechanism for MiT family proteins, and several kinases and phosphatases have been identified to directly determine the transcriptional activities of MiT proteins. In different immune cell types, each MiT family member is shown to play distinct or redundant roles and we expect that there is far more to learn about their functions and regulatory mechanisms in host defense and inflammatory responses.

• 한국작물학회지
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• 제59권3호
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• pp.263-281
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• 2014

전사인자는 식물에서 유전자 발현을 조절하기 위해 필수적이며, 유전자의 promoter나 enhancer 부위에 결합하며, 기본 전사 조절, 전사의 향상, 발달, 세포내 신호전달, 환경에 반응, 세포 주기의 조절 등의 역할을 수행한다. 옥수수 게놈의 염기서열 분석은 전사인자의 유전자 발현 조절의 기작을 이해하는데 도움을 줄 것으로 기대된다. 과거 옥수수의 전체 게놈의 중복으로 옥수수에서 4,000개 이상의 전사인자가 코딩 될 것으로 예상된다. 본 논문에서는 옥수수의 ABI3/VP1, AP2/EREBP, ARF, ARID, AS2, AUX/IAA, BES1, bHLH, bZIP, C2C2-CO-like, C2C2-Dof, C2C2-GATA, C2C2-YABBY, C2H2, E2F/DP, FHA, GARP-ARR-B, GeBP, GRAS, HMG, HSF, MADS, MYB, MYB-related, NAC, PHD, WRKY 전사인자의 특징을 간략히 서술하고, 전사인자의 염기서열을 분석하여 sequence logo를 통하여 각각의 도메인을 표시하였다. 이러한 전사인자 및 관련된 유전자의 분자생물학적 연구는 옥수수에서 중요한 기능을 하는 유전자의 발굴 및 육종을 위한 목표 유전자의 선발에 도움을 줄 것으로 기대된다.

• Journal of Applied Biological Chemistry
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• 제55권1호
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• pp.67-70
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• 2012

Plant MYB transcription factors regulate secondary metabolism, cellular morphogenesis, and plant hormone signaling pathway. MYB proteins in plants consist of two repeats of 50 amino acid residues, which are referred to as R2R3 and they interact with WD40 or basic helix loop helix (bHLH) proteins. Yeast two hybrid assay was determined whether rice MYB protein interacts with either OsTTG1, which contains a WD40 domain, or with OsGL3, which contains a bHLH domain. Among 30 OsMYB proteins, three interacted with OsTTG1 and five interacted with OsGL3. A series of MYB mutants were created to determine the MYB domain important for the interaction with OsTTG1 or OsGL3. By using the yeast two hybrid assay, we found that the R3 motif of OsMYB10 and the R2 motif of OsMYB16 were required for interaction with OsTTG1 and OsGL3 proteins, respectively.

• Molecules and Cells
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• 제39권8호
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• pp.587-593
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• 2016

As sessile organisms, plants must be able to adapt to the environment. Plants respond to the environment by adjusting their growth and development, which is mediated by sophisticated signaling networks that integrate multiple environmental and endogenous signals. Recently, increasing evidence has shown that a bHLH transcription factor PIF4 plays a major role in the multiple signal integration for plant growth regulation. PIF4 is a positive regulator in cell elongation and its activity is regulated by various environmental signals, including light and temperature, and hormonal signals, including auxin, gibberellic acid and brassinosteroid, both transcriptionally and post-translationally. Moreover, recent studies have shown that the circadian clock and metabolic status regulate endogenous PIF4 level. The PIF4 transcription factor cooperatively regulates the target genes involved in cell elongation with hormone-regulated transcription factors. Therefore, PIF4 is a key integrator of multiple signaling pathways, which optimizes growth in the environment. This review will discuss our current understanding of the PIF4-mediated signaling networks that control plant growth.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2005년도 추계학술대회 및 한일 식물생명공학 심포지엄
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• pp.275-275
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• 2005