scholarly journals Grasses use an alternatively wired bHLH transcription factor network to establish stomatal identity

2016 ◽  
Vol 113 (29) ◽  
pp. 8326-8331 ◽  
Author(s):  
Michael T. Raissig ◽  
Emily Abrash ◽  
Akhila Bettadapur ◽  
John P. Vogel ◽  
Dominique C. Bergmann
Keyword(s):  
Transcription Factor ◽  
Cell Fate ◽  
Brachypodium Distachyon ◽  
Bhlh Transcription Factor ◽  
Stomatal Development ◽  
Helix Loop Helix ◽  
Factor Module ◽  
Forward Genetic Screens ◽  
Conserved Genes ◽  
And Behavior

Stomata, epidermal valves facilitating plant–atmosphere gas exchange, represent a powerful model for understanding cell fate and pattern in plants. Core basic helix–loop–helix (bHLH) transcription factors regulating stomatal development were identified in Arabidopsis, but this dicot’s developmental pattern and stomatal morphology represent only one of many possibilities in nature. Here, using unbiased forward genetic screens, followed by analysis of reporters and engineered mutants, we show that stomatal initiation in the grass Brachypodium distachyon uses orthologs of stomatal regulators known from Arabidopsis but that the function and behavior of individual genes, the relationships among genes, and the regulation of their protein products have diverged. Our results highlight ways in which a kernel of conserved genes may be alternatively wired to produce diversity in patterning and morphology and suggest that the stomatal transcription factor module is a prime target for breeding or genome modification to improve plant productivity.

scholarly journals bHLH Transcription Factor Math6 Antagonizes TGF-β Signalling in Reprogramming, Pluripotency and Early Cell Fate Decisions

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 529 ◽  
Author(s):  
Satya Srirama Karthik Divvela ◽  
Patrick Nell ◽  
Markus Napirei ◽  
Holm Zaehres ◽  
Jiayu Chen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Transcription Factor ◽  
Cell Fate ◽  
Pluripotent Stem Cells ◽  
Cellular Reprogramming ◽  
Bhlh Transcription Factor ◽  
Tgf Beta ◽  
Cell Fate Decisions ◽  
Helix Loop Helix ◽  
Induced Pluripotent

The basic helix-loop-helix (bHLH) transcription factor Math6 (Atonal homolog 8; Atoh8) plays a crucial role in a number of cellular processes during embryonic development, iron metabolism and tumorigenesis. We report here on its involvement in cellular reprogramming from fibroblasts to induced pluripotent stem cells, in the maintenance of pluripotency and in early fate decisions during murine development. Loss of Math6 disrupts mesenchymal-to-epithelial transition during reprogramming and primes pluripotent stem cells towards the mesendodermal fate. Math6 can thus be considered a regulator of reprogramming and pluripotent stem cell fate. Additionally, our results demonstrate the involvement of Math6 in SMAD-dependent TGF beta signalling. We furthermore monitor the presence of the Math6 protein during these developmental processes using a newly generated Math6Flag-tag mouse. Taken together, our results suggest that Math6 counteracts TGF beta signalling and, by this, affects the initiating step of cellular reprogramming, as well as the maintenance of pluripotency and early differentiation.

Hxt encodes a basic helix-loop-helix transcription factor that regulates trophoblast cell development

Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2513-2523 ◽  
Author(s):  
J.C. Cross ◽  
M.L. Flannery ◽  
M.A. Blanar ◽  
E. Steingrimsson ◽  
N.A. Jenkins ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Gene Promoter ◽  
Giant Cells ◽  
Placental Lactogen ◽  
Specific Gene ◽  
Bhlh Transcription Factor ◽  
Trophoblast Cells ◽  
Positive Role ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix

Trophoblast cells are the first lineage to form in the mammalian conceptus and mediate the process of implantation. We report the cloning of a basic helix-loop-helix (bHLH) transcription factor gene, Hxt, that is expressed in early trophoblast and in differentiated giant cells. A separate gene, Hed, encodes a related protein that is expressed in maternal deciduum surrounding the implantation site. Overexpression of Hxt in mouse blastomeres directed their development into trophoblast cells in blastocysts. In addition, overexpression of Hxt induced the differentiation of rat trophoblast (Rcho-1) stem cells as assayed by changes in cell adhesion and by activation of the placental lactogen-I gene promoter, a trophoblast giant cell-specific gene. In contrast, the negative HLH regulator, Id-1, inhibited Rcho-1 differentiation and placental lactogen-I transcription. These data demonstrate a role for HLH factors in regulating trophoblast development and indicate a positive role for Hxt in promoting the formation of trophoblast giant cells.

scholarly journals FIT, a regulatory hub for iron deficiency and stress signaling in roots, and FIT-dependent and -independent gene signatures

2020 ◽  
Vol 71 (5) ◽  
pp. 1694-1705 ◽  
Author(s):  
Birte Schwarz ◽  
Petra Bauer
Keyword(s):  
Transcription Factor ◽  
Protein Interactions ◽  
Fe Deficiency ◽  
Bhlh Transcription Factor ◽  
Root Cells ◽  
Gene Signatures ◽  
Helix Loop Helix ◽  
Independent Gene ◽  
Fe Uptake ◽  
Fe Acquisition

Abstract Iron (Fe) is vital for plant growth. Plants balance the beneficial and toxic effects of this micronutrient, and tightly control Fe uptake and allocation. Here, we review the role of the basic helix–loop–helix (bHLH) transcription factor FIT (FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR) in Fe acquisition. FIT is not only essential, it is also a central regulatory hub in root cells to steer and adjust the rate of Fe uptake by the root in a changing environment. FIT regulates a subset of root Fe deficiency (–Fe) response genes. Based on a combination of co-expression network and FIT-dependent transcriptome analyses, we defined a set of FIT-dependent and FIT-independent gene expression signatures and co-expression clusters that encode specific functions in Fe regulation and Fe homeostasis. These gene signatures serve as markers to integrate novel regulatory factors and signals into the –Fe response cascade. FIT forms a complex with bHLH subgroup Ib transcription factors. Furthermore, it interacts with key regulators from different signaling pathways that either activate or inhibit FIT function to adjust Fe acquisition to growth and environmental constraints. Co-expression clusters and FIT protein interactions suggest a connection of –Fe with ABA responses and root cell elongation processes that can be explored in future studies.

scholarly journals Tomato bHLH132 Transcription Factor Controls Growth and Defense and Is Activated by Xanthomonas euvesicatoria Effector XopD During Pathogenesis

2019 ◽  
Vol 32 (12) ◽  
pp. 1614-1622 ◽  
Author(s):  
Jung-Gun Kim ◽  
Mary Beth Mudgett
Keyword(s):  
Transcription Factor ◽  
Protease Activity ◽  
Transcriptional Profiling ◽  
Bhlh Transcription Factor ◽  
Transcription Activator ◽  
Tal Effectors ◽  
Sumo Protease ◽  
Tal Effector ◽  
Helix Loop Helix ◽  
Xanthomonas Euvesicatoria

Effector-dependent manipulation of host transcription is a key virulence mechanism used by Xanthomonas species causing bacterial spot disease in tomato and pepper. Transcription activator-like (TAL) effectors employ novel DNA-binding domains to directly activate host transcription, whereas the non-TAL effector XopD uses a small ubiquitin-like modifier (SUMO) protease activity to represses host transcription. The targets of TAL and non-TAL effectors provide insight to the genes governing susceptibility and resistance during Xanthomonas infection. In this study, we investigated the extent to which the X. euvesicatoria non-TAL effector strain Xe85-10 activates tomato transcription to gain new insight to the transcriptional circuits and virulence mechanisms associated with Xanthomonas euvesicatoria pathogenesis. Using transcriptional profiling, we identified a putative basic helix-loop-helix (bHLH) transcription factor, bHLH132, as a pathogen-responsive gene that is moderately induced by microbe-associated molecular patterns and defense hormones and is highly induced by XopD during X. euvesicatoria infection. We also found that activation of bHLH132 transcription requires the XopD SUMO protease activity. Silencing bHLH132 mRNA expression results in stunted tomato plants with enhanced susceptibility to X. euvesicatoria infection. Our work suggests that bHLH132 is required for normal vegetative growth and development as well as resistance to X. euvesicatoria. It also suggests new transcription-based models describing XopD virulence and recognition in tomato.

scholarly journals The Basic-Region Helix-Loop-Helix Transcription Factor DevR Significantly Affects Polysaccharide Metabolism inAspergillus oryzae

2019 ◽  
Vol 85 (8) ◽  
Author(s):  
Miao Zhuang ◽  
Zhi-Min Zhang ◽  
Long Jin ◽  
Bao-Teng Wang ◽  
Yasuji Koyama ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Aspergillus Oryzae ◽  
Bhlh Transcription Factor ◽  
Regulation Mechanism ◽  
Starch Metabolism ◽  
Poor Growth ◽  
Content Type ◽  
Helix Loop Helix ◽  
Amylase Production ◽  
Basic Region

ABSTRACTBasic-region helix-loop-helix (bHLH) proteins are a superfamily of transcription factors that are often involved in the control of growth and differentiation. Recently, it was reported that the bHLH transcription factor DevR is involved in both asexual and sexual development inAspergillus nidulansand regulates the conidial melanin production inAspergillus fumigatus. In this study, we identified and characterized anAspergillus oryzaegene that showed high similarity withdevRofA. nidulansandA. fumigatus(AodevR). In the AodevR-disrupted strain, growth was delayed and the number of conidia was decreased on Czapek-Dox (CD) minimal agar plates, but the conidiation was partially recovered by adding 0.6 M KCl. Simultaneously, the overexpression of AodevRwas induced and resulted in extremely poor growth when the carbon source changed from glucose to polysaccharide (dextrin) in the CD agar plate. Scanning electron microscopy (SEM) indicated that the overexpression of AodevRresulted in extremely thin aberrant hyphal morphology. Conversely, the deletion of AodevRresulted in thicker hyphae and in more resistance to Congo red relative to the control strain. Quantitative reverse transcriptase PCR (RT-PCR) further indicated that AoDevR significantly affects chitin and starch metabolism, and importantly, the overexpression of AodevRinhibited the expression of genes related to starch degradation. A yeast one-hybrid assay suggested that the DevR protein possibly interacted with the promoter ofamyR, which encodes a transcription factor involved in amylase production. Importantly, AoDevR is involved in polysaccharide metabolism and affects the growth of theA. oryzaestrain.IMPORTANCEAspergillus oryzaeis an industrially important filamentous fungus; therefore, a clear understanding of its polysaccharide metabolism and utilization is very important for its industrial utilization. In this study, we revealed that the basic-region helix-loop-helix (bHLH) transcription factor AoDevR is importantly involved in chitin and starch metabolism inA. oryzae. The overexpression of AodevRstrongly suppressed the expression of amylase-related genes. The results of a yeast one-hybrid assay suggested that the DevR protein potentially interacts with the promoter ofamyR, which encodes a transcription factor involved in amylase production and starch utilization. This study provides new insight for further revealing the regulation mechanism of amylase production inA. oryzae.

The basic helix-loop-helix transcription factor bHLH95 affects fruit ripening and multiple metabolisms in tomato

2020 ◽  
Vol 71 (20) ◽  
pp. 6311-6327
Author(s):  
Lincheng Zhang ◽  
Jing Kang ◽  
Qiaoli Xie ◽  
Jun Gong ◽  
Hui Shen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Fruit Ripening ◽  
Tomato Fruit ◽  
Soluble Sugar ◽  
Glutathione Metabolism ◽  
Bhlh Transcription Factor ◽  
Total Carotenoids ◽  
Helix Loop Helix ◽  
Tomato Fruit Ripening

Abstract Ethylene signaling pathways regulate several physiological alterations that occur during tomato fruit ripening, such as changes in colour and flavour. The mechanisms underlying the transcriptional regulation of genes in these pathways remain unclear, although the role of the MADS-box transcription factor RIN has been widely reported. Here, we describe a bHLH transcription factor, SlbHLH95, whose transcripts accumulated abundantly in breaker+4 and breaker+7 fruits compared with rin (ripening inhibitor) and Nr (never ripe) mutants. Moreover, the promoter activity of SlbHLH95 was regulated by RIN in vivo. Suppression of SlbHLH95 resulted in reduced sensitivity to ethylene, decreased accumulation of total carotenoids, and lowered glutathione content, and inhibited the expression of fruit ripening- and glutathione metabolism-related genes. Conversely, up-regulation of SlbHLH95 in wild-type tomato resulted in higher sensitivity to ethylene, increased accumulation of total carotenoids, slightly premature ripening, and elevated accumulation of glutathione, soluble sugar, and starch. Notably, overexpression of SlbHLH95 in rin led to the up-regulated expression of fruit ripening-related genes (FUL1, FUL2, SAUR69, ERF4, and CNR) and multiple glutathione metabolism-related genes (GSH1, GSH2, GSTF1, and GSTF5). These results clarified that SlbHLH95 participates in the regulation of fruit ripening and affects ethylene sensitivity and multiple metabolisms targeted by RIN in tomato.

scholarly journals Basic Helix-Loop-Helix (bHLH) Transcription Factors Regulate a Wide Range of Functions in Arabidopsis

2021 ◽  
Vol 22 (13) ◽  
pp. 7152
Author(s):  
Yaqi Hao ◽  
Xiumei Zong ◽  
Pan Ren ◽  
Yuqi Qian ◽  
Aigen Fu
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Target Genes ◽  
Gene Families ◽  
Bhlh Transcription Factor ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Wide Range ◽  
Range Of Functions ◽  
Eukaryotic Organisms

The basic helix-loop-helix (bHLH) transcription factor family is one of the largest transcription factor gene families in Arabidopsis thaliana, and contains a bHLH motif that is highly conserved throughout eukaryotic organisms. Members of this family have two conserved motifs, a basic DNA binding region and a helix-loop-helix (HLH) region. These proteins containing bHLH domain usually act as homo- or heterodimers to regulate the expression of their target genes, which are involved in many physiological processes and have a broad range of functions in biosynthesis, metabolism and transduction of plant hormones. Although there are a number of articles on different aspects to provide detailed information on this family in plants, an overall summary is not available. In this review, we summarize various aspects of related studies that provide an overview of insights into the pleiotropic regulatory roles of these transcription factors in plant growth and development, stress response, biochemical functions and the web of signaling networks. We then provide an overview of the functional profile of the bHLH family and the regulatory mechanisms of other proteins.

scholarly journals A bHLH transcription factor (VfTT8) underlies zt2, the locus determining zero tannin content in faba bean (Vicia faba L.)

2020 ◽  
Author(s):  
Natalia Gutierrez ◽  
Carmen M. Avila ◽  
Ana M. Torres
Keyword(s):  
Transcription Factor ◽  
Vicia Faba ◽  
Faba Bean ◽  
Regulatory Gene ◽  
Value Added ◽  
Flower Colour ◽  
Genomic Region ◽  
Candidate Gene Approach ◽  
Bhlh Transcription Factor ◽  
Helix Loop Helix

AbstractFaba bean (Vicia faba L.) is an important protein-rich fodder crop widely cultivated in temperate areas. However, antinutritional compounds such as condensed tannins, limit the use of this protein source in monogastric feed formulations. Previous studies demonstrated that two recessive and complementary genes, zt1 and zt2, control the absence of tannin and the white flower colour in faba bean. An ortholog of the Medicago WD40 transcription factor, (TTG1) was reported to encode the zt1 phenotypes but the responsible gene for zt2 is still unknown. A candidate gene approach combined with linkage mapping, comparative genomics and gene expression has been used in this study to fine map the zt2 genomic region and to identify the regulatory gene controlling both traits. Seventy-two genes, including 23 regulatory genes (MYB and bHLH) predicted to be associated with anthocyanin expression together with WRKY proteins were screened and genotyped in three mapping populations. The linkage groups constructed identified the regulatory gene, TRANSPARENT TESTA8 (TT8), encoding a basic helix-loop-helix transcription factor (bHLH), as the best candidate for zt2. This finding was supported by qPCR analyses and further validated in different genetic backgrounds. Accordingly, VfTT8 was down-regulated in white flowered types, in contrast to the levels of expression in wild genotypes. Our results provide new insights on the regulatory mechanisms for tannin biosynthesis in faba bean and will favour the development of an ultimate zt2 diagnostic marker for the fast generation of new value-added cultivars free of tannins and improved nutritional value.

scholarly journals Hand2 inhibits kidney specification while promoting vein formation within the posterior mesoderm

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Elliot A Perens ◽  
Zayra V Garavito-Aguilar ◽  
Gina P Guio-Vega ◽  
Karen T Peña ◽  
Yocheved L Schindler ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Fate ◽  
Zinc Finger ◽  
Kidney Development ◽  
Bhlh Transcription Factor ◽  
Lateral Boundary ◽  
Zinc Finger Transcription Factor ◽  
Cell Fate Decisions ◽  
Intermediate Mesoderm ◽  
Vein Formation

Proper organogenesis depends upon defining the precise dimensions of organ progenitor territories. Kidney progenitors originate within the intermediate mesoderm (IM), but the pathways that set the boundaries of the IM are poorly understood. Here, we show that the bHLH transcription factor Hand2 limits the size of the embryonic kidney by restricting IM dimensions. The IM is expanded in zebrafish hand2 mutants and is diminished when hand2 is overexpressed. Within the posterior mesoderm, hand2 is expressed laterally adjacent to the IM. Venous progenitors arise between these two territories, and hand2 promotes venous development while inhibiting IM formation at this interface. Furthermore, hand2 and the co-expressed zinc-finger transcription factor osr1 have functionally antagonistic influences on kidney development. Together, our data suggest that hand2 functions in opposition to osr1 to balance the formation of kidney and vein progenitors by regulating cell fate decisions at the lateral boundary of the IM.

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