Hey Basic Helix-Loop-Helix Transcription Factors Are Repressors of GATA4 and GATA6 and Restrict Expression of the GATA Target Gene ANF in Fetal Hearts

ABSTRACT The Hey basic helix-loop-helix transcription factors are downstream effectors of Notch signaling in the cardiovascular system. Mice lacking Hey2 develop cardiac hypertrophy, often associated with congenital heart defects, whereas combined Hey1/Hey2 deficiency leads to severe vascular defects and embryonic lethality around embryonic day E9.5. The molecular basis of these disorders is poorly understood, however, since target genes of Hey transcription factors in the affected tissues remain elusive. To identify genes regulated by Hey factors we have generated a conditional Hey1 knockout mouse. This strain was used to generate paired Hey2- and Hey1/2-deficient embryonic stem cell lines. Comparison of these cell lines by microarray analysis identified GATA4 and GATA6 as differentially expressed genes. Loss of Hey1/2 leads to elevated GATA4/6 and ANF mRNA levels in embryoid bodies, while forced expression of Hey factors strongly represses expression of the GATA4 and GATA6 promoter in various cell lines. In addition, the promoter activity of the GATA4/6 target gene ANF was inhibited by Hey1, Hey2, and HeyL. Protein interaction and mutation analyses suggest that repression is due to direct binding of Hey proteins to GATA4 and GATA6, blocking their transcriptional activity. In Hey2-deficient fetal hearts we observed elevated mRNA levels of ANF and CARP. Expression of ANF and Hey2 is normally restricted to the trabecular and compact myocardial layer, respectively. Intriguingly, loss of Hey2 leads to ectopic ANF expression in the compact layer, suggesting a direct role for Hey2 in limiting ANF expression in this cardiac compartment.

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

International Journal of Molecular Sciences ◽

10.3390/ijms22137152 ◽

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.

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Dual role of the basic helix-loop-helix transcription factor scleraxis in mesoderm formation and chondrogenesis during mouse embryogenesis

Development ◽

10.1242/dev.126.19.4317 ◽

1999 ◽

Vol 126 (19) ◽

pp. 4317-4329 ◽

Cited By ~ 7

Author(s):

D. Brown ◽

D. Wagner ◽

X. Li ◽

J.A. Richardson ◽

E.N. Olson

Keyword(s):

Transcription Factor ◽

Target Genes ◽

Embryonic Stem ◽

Primitive Streak ◽

Axial Skeleton ◽

Bhlh Transcription Factor ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Mesoderm Formation ◽

Cell Layers

Scleraxis is a basic helix-loop-helix (bHLH) transcription factor shown previously to be expressed in developing chondrogenic cell lineages during embryogenesis. To investigate its function in embryonic development, we produced scleraxis-null mice by gene targeting. Homozygous mutant embryos developed normally until the early egg cylinder stage (embryonic day 6.0), when they became growth-arrested and failed to gastrulate. Consistent with this early embryonic phenotype, scleraxis was found to be expressed throughout the embryo at the time of gastrulation before becoming restricted to chondrogenic precursor cells at embryonic day 9.5. At the time of developmental arrest, scleraxis-null embryos consisted of ectodermal and primitive endodermal cell layers, but lacked a primitive streak or recognizable mesoderm. Analysis of molecular markers of the three embryonic germ layers confirmed that scleraxis mutant embryos were unable to form mesoderm. By generating chimeric embryos, using lacZ-marked scleraxis-null and wild-type embryonic stem cells, we examined the ability of mutant cells to contribute to regions of the embryo beyond the time of lethality of homozygous mutants. Scleraxis-null cells were specifically excluded from the sclerotomal compartment of somites, which gives rise to the axial skeleton, and from developing ribs, but were able to contribute to most other regions of the embryo, including mesoderm-derived tissues. These results reveal an essential early role for scleraxis in mesoderm formation, as well as a later role in formation of somite-derived chondrogenic lineages, and suggest that scleraxis target genes mediate these processes.

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Expression and methylation of imprinted genes during in vitro differentiation of mouse parthenogenetic and androgenetic embryonic stem cell lines

Development ◽

10.1242/dev.120.6.1651 ◽

1994 ◽

Vol 120 (6) ◽

pp. 1651-1660 ◽

Cited By ~ 6

Author(s):

P. Szabo ◽

J.R. Mann

Keyword(s):

Stem Cell ◽

Embryonic Stem Cell ◽

Cell Lines ◽

Embryonic Stem ◽

Embryoid Bodies ◽

Imprinted Genes ◽

Mrna Levels ◽

Wild Type ◽

Stem Cell Lines

Messenger RNA and methylation levels of four imprinted genes, H19, Igf2r, Igf-2 and Snrpn were examined by northern and Southern blotting in mouse parthenogenetic, androgenetic and normal or wild-type embryonic stem cell lines during their differentiation in vitro as embryoid bodies. In most instances, mRNA levels in parthenogenetic and androgenetic embryoid bodies differed from wild type as expected from previously determined patterns of monoallelic expression in midgestation embryos and at later stages of development. These findings implicate aberrant mRNA levels of these genes in the abnormal development of parthenogenetic and androgenetic embryos and chimeras. Whereas complete silence of one of the parental alleles has previously been observed in vivo, we detected some mRNA in the corresponding embryonic stem cell line. This ‘leakage’ phenomenon could be explained by partial erasure, bypass or override of imprints, or could represent the actual activity status at very early stages of development. The mRNA levels of H19, Igf2r and Igf-2 and the degree of methylation at specific associated sequences were correlated according to previous studies in embryos, and thereby are consistent with suggestions that the methylation might play a role in controlling transcription of these genes. Paternal-specific methylation of the H19 promoter region is absent in sperm, yet we observed its presence in undifferentiated androgenetic embryonic stem cells, or before the potential expression phase of this gene in embryoid bodies. As such methylation is likely to invoke a repressive effect, this finding raises the possibility that it is part of the imprinting mechanism of H19, taking the form of a secondary imprint or postfertilization epigenetic modification necessary for repression of the paternal allele.

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Domains outside of the DNA-binding domain impart target gene specificity to myogenin and MRF4

Molecular and Cellular Biology ◽

10.1128/mcb.11.12.6103-6108.1991 ◽

1991 ◽

Vol 11 (12) ◽

pp. 6103-6108

Author(s):

T Chakraborty ◽

E N Olson

Keyword(s):

Creatine Kinase ◽

Transcription Factors ◽

Dna Binding ◽

Target Gene ◽

Binding Domain ◽

Dna Binding Domain ◽

Muscle Creatine Kinase ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Muscle Creatine

Myogenin and MRF4 belong to the MyoD family of muscle-specific transcription factors, which can activate myogenesis when introduced into nonmyogenic cells. These proteins share homology within a basic-helix-loop-helix motif that mediates DNA binding and dimerization, but they are divergent in their amino and carboxyl termini. Although myogenin and MRF4 bind the same sequence within the muscle creatine kinase enhancer, only myogenin efficiently transactivates this enhancer. By creating chimeras of myogenin and MRF4, we show that the specificities of these factors for transactivation of the muscle creatine kinase enhancer can be interchanged by swapping their amino and carboxyl termini. Within these chimeras, strong cooperation between the amino and carboxyl termini was observed. These findings suggest that myogenin and MRF4 discriminate between muscle-specific enhancers and that target gene specificity is determined by domains surrounding the basic-helix-loop-helix region.

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Domains outside of the DNA-binding domain impart target gene specificity to myogenin and MRF4.

Molecular and Cellular Biology ◽

10.1128/mcb.11.12.6103 ◽

1991 ◽

Vol 11 (12) ◽

pp. 6103-6108 ◽

Cited By ~ 25

Author(s):

T Chakraborty ◽

E N Olson

Keyword(s):

Creatine Kinase ◽

Transcription Factors ◽

Dna Binding ◽

Target Gene ◽

Binding Domain ◽

Dna Binding Domain ◽

Muscle Creatine Kinase ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Muscle Creatine

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Calcium Regulation of Myogenesis by Differential Calmodulin Inhibition of Basic Helix-Loop-Helix Transcription Factors

Molecular Biology of the Cell ◽

10.1091/mbc.e07-09-0886 ◽

2008 ◽

Vol 19 (6) ◽

pp. 2509-2519 ◽

Cited By ~ 21

Author(s):

Jannek Hauser ◽

Juha Saarikettu ◽

Thomas Grundström

Keyword(s):

Transcription Factors ◽

Target Genes ◽

Myogenic Differentiation ◽

Bhlh Protein ◽

Channel Blockers ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

E Protein ◽

Bhlh Transcription Factors

The members of the MyoD family of basic helix-loop-helix (bHLH) transcription factors are critical regulators of skeletal muscle differentiation that function as heterodimers with ubiquitously expressed E-protein bHLH transcription factors. These heterodimers must compete successfully with homodimers of E12 and other E-proteins to enable myogenesis. Here, we show that E12 mutants resistant to Ca2+-loaded calmodulin (CaM) inhibit MyoD-initiated myogenic conversion of transfected fibroblasts. Ca2+ channel blockers reduce, and Ca2+ stimulation increases, transcription by coexpressed MyoD and wild-type E12 but not CaM-resistant mutant E12. Furthermore, CaM-resistant E12 gives lower MyoD binding and higher E12 binding to a MyoD-responsive promoter in vivo and cannot rescue myogenic differentiation that has been inhibited by siRNA against E12 and E47. Our data support the concept that Ca2+-loaded CaM enables myogenesis by inhibiting DNA binding of E-protein homodimers, thereby promoting occupancy of myogenic bHLH protein/E-protein heterodimers on promoters of myogenic target genes.

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Overexpression of Basic Helix-Loop-Helix Transcription Factors Enhances Neuronal Differentiation of Fetal Human Neural Progenitor Cells in Various Ways

Stem Cells and Development ◽

10.1089/scd.2011.0079 ◽

2012 ◽

Vol 21 (4) ◽

pp. 539-553 ◽

Cited By ~ 13

Author(s):

Angéline Serre ◽

Evan Y. Snyder ◽

Jacques Mallet ◽

Delphine Buchet

Keyword(s):

Transcription Factors ◽

Progenitor Cells ◽

Neuronal Differentiation ◽

Neural Progenitor Cells ◽

Neural Progenitor ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Human Neural Progenitor Cells

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A Classification of Basic Helix-Loop-Helix Transcription Factors of Soybean

International Journal of Genomics ◽

10.1155/2015/603182 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 16

Author(s):

Karen A. Hudson ◽

Matthew E. Hudson

Keyword(s):

Transcription Factors ◽

Genome Sequence ◽

Search Algorithm ◽

Soybean Genome ◽

Binding Potential ◽

Future Research ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Bhlh Genes ◽

Wide Range

The complete genome sequence of soybean allows an unprecedented opportunity for the discovery of the genes controlling important traits. In particular, the potential functions of regulatory genes are a priority for analysis. The basic helix-loop-helix (bHLH) family of transcription factors is known to be involved in controlling a wide range of systems critical for crop adaptation and quality, including photosynthesis, light signalling, pigment biosynthesis, and seed pod development. Using a hidden Markov model search algorithm, 319 genes with basic helix-loop-helix transcription factor domains were identified within the soybean genome sequence. These were classified with respect to their predicted DNA binding potential, intron/exon structure, and the phylogeny of the bHLH domain. Evidence is presented that the vast majority (281) of these 319 soybean bHLH genes are expressed at the mRNA level. Of these soybean bHLH genes, 67% were found to exist in two or more homeologous copies. This dataset provides a framework for future studies on bHLH gene function in soybean. The challenge for future research remains to define functions for the bHLH factors encoded in the soybean genome, which may allow greater flexibility for genetic selection of growth and environmental adaptation in this widely grown crop.

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