Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rice atypical HLH protein Oryza sativa BRASSINOSTEROID UPREGULATED 1-LIKE1 (OsBUL1) is preferentially expressed in the lamina joint where it controls cell elongation and positively affects leaf angles. OsBUL1 knockout mutant (osbul1) and transgenic rice for double-stranded RNA interference (dsRNAi) of OsBUL1 produced erect leaves with smaller grains, whereas OsBUL1 overexpressors and an activation tagging line of OsBUL1 exhibited increased lamina inclination and grain size. Moreover, OsBUL1 expression was induced by brassinolide (BL) and osbul1 did not respond to BL treatment. To understand the molecular network of OsBUL1 function in rice, we isolated a novel OsBUL1-interacting protein, LO9-177, an uncharacterized protein containing a KxDL motif, and functionally studied it with respect to the lamina inclination and grain size of rice. OsBUL1 COMPLEX1 (OsBC1) is a basic helix-loop-helix (bHLH) transcriptional activator that interacts with OsBUL1 only in the presence of LO9-177 forming a possible trimeric complex for cell elongation in the lamina joint of rice. Expression of OsBC1 is also upregulated by BL and has a similar pattern to that of OsBUL1 Transgenic rice plants expressing OsBC1 under the control of OsBUL1 promoter showed increased grain size as well as leaf bending, while transgenic lines for dsRNAi and/or expressing a dominant repressor form of OsBC1 displayed reduced plant height and grain size. Together, these results demonstrated that a novel protein complex consisting of OsBUL1, LO9-177, and OsBC1 is associated with the HLH-bHLH system, providing new insight into the molecular functional network based on HLH-bHLH proteins for cell elongation.
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PMID:Rice Leaf Angle and Grain Size Are Affected by the OsBUL1 Transcriptional Activator Complex. 2787 91

Tenomodulin (Tnmd) is a type II transmembrane glycoprotein predominantly expressed in tendons and ligaments. We found that scleraxis (Scx), a member of the Twist-family of basic helix-loop-helix transcription factors, is a transcriptional activator of Tnmd expression in tenocytes. During embryonic development, Scx expression preceded that of Tnmd. Tnmd expression was nearly absent in tendons and ligaments of Scx-deficient mice generated by transcription activator-like effector nucleases-mediated gene disruption. Tnmd mRNA levels were dramatically decreased during serial passages of rat tenocytes. Scx silencing by small interfering RNA significantly suppressed endogenous Tnmd mRNA levels in tenocytes. Mouse Tnmd contains five E-box sites in the ~1-kb 5'-flanking region. A 174-base pair genomic fragment containing a TATA box drives transcription in tenocytes. Enhancer activity was increased in the upstream region (-1030 to -295) of Tnmd in tenocytes, but not in NIH3T3 and C3H10T1/2 cells. Preferential binding of both Scx and Twist1 as a heterodimer with E12 or E47 to CAGATG or CATCTG and transactivation of the 5'-flanking region were confirmed by electrophoresis mobility shift and dual luciferase assays, respectively. Scx directly transactivates Tnmd via these E-boxes to positively regulate tenocyte differentiation and maturation.
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PMID:Scleraxis is a transcriptional activator that regulates the expression of Tenomodulin, a marker of mature tenocytes and ligamentocytes. 2945 33

Jasmonates (JAs) are integral to various defense responses and induce biosynthesis of many secondary metabolites. MYC2, a basic helix-loop-helix (bHLH) transcription factor (TF), acts as a transcriptional activator of JA signaling. MYC2 is repressed by the JASMONATE ZIM-domain (JAZ) proteins in the absence of JA, but de-repressed by the protein complex SCFCOI1 on perception of JA. We previously reported that overexpression of SmMYC2 promotes the production of salvianolic acid B (Sal B) in Salvia miltiorrhiza. However, the responsible molecular mechanism is unclear. Here, we showed that SmMYC2 binds to and activates the promoters of its target genes SmTAT1, SmPAL1, and SmCYP98A14 to activate Sal B accumulations. SmbHLH37, a novel bHLH gene significantly up-regulated by constitutive expression of SmMYC2, was isolated from S. miltiorrhiza for detailed functional characterization. SmbHLH37 forms a homodimer and interacts with SmJAZ3/8. Overexpression of SmbHLH37 substantially decreased yields of Sal B. SmbHLH37 binds to the promoters of its target genes SmTAT1 and SmPAL1 and blocks their expression to suppress the pathway for Sal B biosynthesis. These results indicate that SmbHLH37 negatively regulates JA signaling and functions antagonistically with SmMYC2 in regulating Sal B biosynthesis in S. miltiorrhiza.
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PMID:SmbHLH37 Functions Antagonistically With SmMYC2 in Regulating Jasmonate-Mediated Biosynthesis of Phenolic Acids in Salvia miltiorrhiza. 3052 67

In citrus, the production of anthocyanin pigments requires the activity of the transcriptional activator Ruby. Consequently, loss-of-function mutations in Ruby result in an anthocyaninless phenotype [1]. Several citrus accessions, however, have lost the ability to produce these pigments despite the presence of wild-type Ruby alleles. These specific mutants have captivated the interest of botanists and breeders for centuries because the lack of anthocyanins in young leaves and flowers is also associated with a lack of proanthocyanidins in seeds and, most notably, with an extreme reduction in fruit acidity (involving about a three-unit change in pH). These mutants have been defined collectively as "acidless" [2-4]. We have identified Noemi, which encodes a basic helix-loop-helix (bHLH) transcription factor and which controls these apparently unrelated processes. In accessions of Citron, limetta, sweet lime, lemon, and sweet orange, acidless phenotypes are associated with large deletions or insertions of retrotransposons in the Noemi gene. In two accessions of limetta, a change in the core promoter region of Noemi is associated with reduced expression and increased pH of juice, indicating that Noemi is a major determinant of fruit acidity. The characterization of the Noemi locus in a number of varieties of Citron indicates that one specific mutation is ancient. The presence of this allele in Chinese fingered Citrons and in those used in the Sukkot Jewish ritual [5] illuminates the path of domestication of Citron, the first citrus species to be cultivated in the Mediterranean. This allele has been inherited in Citron-derived hybrids with long histories of cultivation.
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PMID:Noemi Controls Production of Flavonoid Pigments and Fruit Acidity and Illustrates the Domestication Routes of Modern Citrus Varieties. 3089 37

Iron (Fe) is a major micronutrient which influences plant growth, development, quality and yield. Although basic helix-loop-helix (bHLH) transcription factors (TFs) which respond to iron deficiency have been identified, the molecular mechanisms have not been fully elucidated. In this study, a novel bHLH TF, NtbHLH1, was found to be induced by iron deficiency. Further analysis indicated that NtbHLH1 is localized to the nucleus and functions as a transcriptional activator. Moreover, overexpression of NtbHLH1 resulted in longer roots, altered rhizosphere pH and increased ferric-chelate reductase activity in iron deficient conditions. Overall these changes resulted in increased iron uptake relative to wild type plants. NtbHLH1 mutants, on the other hand, had an opposite phenotype. In addition, transcript levels of seven genes associated with iron deficiency response were higher in the NtbHLH1 overexpression transgenic plants and lower in ntbhlh1 relative to the WT under iron deficiency treatment. Taken together, these results demonstrated that NtbHLH1 plays a key role in iron deficiency response and they provide new insights into the molecular basis of iron homeostasis in tobacco.
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PMID:A novel bHLH transcription factor, NtbHLH1, modulates iron homeostasis in tobacco (Nicotiana tabacum L.). 3175 26

Light and high temperature promote plant cell elongation. PHYTOCHROME INTERACTING FACTOR4 (PIF4, a typical basic helix-loop-helix [bHLH] transcriptional activator) and the non-DNA-binding atypical HLH inhibitors PHYTOCHROME RAPIDLY REGULATED1 (PAR1) and LONG HYPOCOTYL IN FAR-RED 1 (HFR1) competitively regulate cell elongation in response to light conditions and high temperature. However, the underlying mechanisms have not been fully clarified. Here, we show that in Arabidopsis thaliana, the bHLH transcription factor CRYPTOCHROME-INTERACTING BASIC HELIX-LOOP-HELIX 1 (CIB1) positively regulates cell elongation under the control of PIF4, PAR1, and HFR1. Furthermore, PIF4 directly regulates CIB1 expression by interacting with its promoter, and PAR1 and HFR1 interfere with PIF4 binding to the CIB1 promoter. CIB1 activates genes that function in cell elongation, and PAR1 interferes with the DNA binding activity of CIB1, thus suppressing cell elongation. Hence, two antagonistic HLH/bHLH systems, the PIF4-PAR1/HFR1 and CIB1-PAR1 systems, regulate cell elongation in response to light and high temperature. We thus demonstrate the important role of non-DNA-binding small HLH proteins in the transcriptional regulation of cell elongation in plants.
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PMID:The CIB1 Transcription Factor Regulates Light- and Heat-inducible Cell Elongation via a Two-step HLH/bHLH System. 3325 52


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