scholarly journals PTF1 Is an Organ-Specific and Notch-Independent Basic Helix-Loop-Helix Complex Containing the Mammalian Suppressor of Hairless (RBP-J) or Its Paralogue, RBP-L

2006 ◽  
Vol 26 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Thomas M. Beres ◽  
Toshihiko Masui ◽  
Galvin H. Swift ◽  
Ling Shi ◽  
R. Michael Henke ◽  
...  
Keyword(s):  
Genetic Disorder ◽  
Bhlh Protein ◽  
Peptide Motifs ◽  
Basic Helix Loop Helix ◽  
Class A ◽  
Helix Loop Helix ◽  
Notch Intracellular Domain ◽  
Suppressor Of Hairless ◽  
Organ Specific ◽  
Human Genetic Disorder

ABSTRACT PTF1 is a trimeric transcription factor essential to the development of the pancreas and to the maintenance of the differentiated state of the adult exocrine pancreas. It comprises a dimer of P48/PTF1a (a pancreas and neural restricted basic helix-loop-helix [bHLH] protein) and a class A bHLH protein, together with a third protein that we show can be either the mammalian Suppressor of Hairless (RBP-J) or its paralogue, RBP-L. In mature acinar cells, PTF1 exclusively contains the RBP-L isoform and is bound to the promoters of acinar specific genes. P48 interacts with the RBP subunit primarily through two short conserved tryptophan-containing motifs, similar to the motif of the Notch intracellular domain (NotchIC) that interacts with RBP-J. The transcriptional activities of the J and L forms of PTF1 are independent of Notch signaling, because P48 occupies the NotchIC docking site on RBP-J and RBP-L does not bind the NotchIC. Mutations that delete one or both of the RBP-interacting motifs of P48 eliminate RBP-binding and are associated with a human genetic disorder characterized by pancreatic and cerebellar agenesis, which indicates that the association of P48 and RBPs is required for proper embryonic development. The presence of related peptide motifs in other transcription factors indicates a broader Notch-independent function for RBPJ/SU(H).

Human Hand1 basic helix-loop-helix (bHLH) protein: extra-embryonic expression pattern, interaction partners and identification of its transcriptional repressor domains

2002 ◽  
Vol 361 (3) ◽  
pp. 641-651 ◽  
Author(s):  
Martin KNÖFLER ◽  
Gudrun MEINHARDT ◽  
Sandra BAUER ◽  
Thomas LOREGGER ◽  
Richard VASICEK ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Transcriptional Repressor ◽  
Bhlh Protein ◽  
Bhlh Transcription Factor ◽  
Basic Helix Loop Helix ◽  
Class A ◽  
Helix Loop Helix ◽  
Bhlh Factors ◽  
E Boxes

The basic helix-loop-helix (bHLH) transcription factor, Hand1, plays an important role in the development of the murine extra-embryonic trophoblast cell lineage. In the present study, we have analysed the expression of Hand1 in human extra-embryonic cell types and determined its binding specificity and transcriptional activity upon interaction with different class A bHLH factors. Northern blotting and in situ hybridization showed that Hand1 mRNA is specifically expressed in amnion cells at different stages of gestation. Accordingly, we demonstrate that the protein is exclusively produced in the amniotic epithelium in vivo and in purified amnion cells in vitro using a novel polyclonal Hand1 antiserum. Reverse transcriptase-PCR and immunohistochemical staining of blastocysts revealed the production of Hand1 mRNA and polypeptide in the trophectodermal cell layer. In the presence of E12/E47, Hand1 stimulated the transcription of luciferase reporters harbouring degenerate E-boxes, suggesting that E-proteins are potential dimerization partners in trophoblastic tumour and amnion cells. In contrast, Hand1 diminished E12/E47-dependent transcription of reporters containing perfect E-boxes by inhibiting the interaction of Hand1/E-protein heterodimers with the palindromic cognate sequence. Furthermore, we show that Hand1 down-regulated GAL—E12-dependent reporter expression, indicating that the protein can also act directly as a transcriptional repressor. Mutational analyses of GAL-Hand1 suggested that two protein regions located within its N-terminal portion mainly confer the repressing activity. In conclusion, human Hand1 may play an important role in the differentiation of the amniotic membrane and the pre-implanting trophoblast. Furthermore, the data suggest that Hand1 can act as a repressor by two independent mechanisms; sequestration of class A bHLH factors from E-boxes and inhibition of their transcriptional activity.

A novel basic helix-loop-helix protein is expressed in muscle attachment sites of the Drosophila epidermis

1994 ◽  
Vol 14 (6) ◽  
pp. 4145-4154
Author(s):  
P Armand ◽  
A C Knapp ◽  
A J Hirsch ◽  
E F Wieschaus ◽  
M D Cole
Keyword(s):  
Distinct Pattern ◽  
Bhlh Protein ◽  
Muscle Attachment ◽  
Muscle Creatine Kinase ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Attachment Sites ◽  
Bhlh Genes ◽  
Somatic Muscles ◽  
Muscle Attachment Sites

We have found that a novel basic helix-loop-helix (bHLH) protein is expressed almost exclusively in the epidermal attachments sites for the somatic muscles of Drosophila melanogaster. A Drosophila cDNA library was screened with radioactively labeled E12 protein, which can dimerize with many HLH proteins. One clone that emerged from this screen encoded a previously unknown protein of 360 amino acids, named delilah, that contains both basic and HLH domains, similar to a group of cellular transcription factors implicated in cell type determination. Delilah protein formed heterodimers with E12 that bind to the muscle creatine kinase promoter. In situ hybridization with the delilah cDNA localized the expression of the gene to a subset of cells in the epidermis which form a distinct pattern involving both the segmental boundaries and intrasegmental clusters. This pattern was coincident with the known sites of attachment of the somatic muscles to tendon cells in the epidermis. delilah expression persists in snail mutant embryos which lack mesoderm, indicating that expression of the gene was not induced by attachment of the underlying muscles. The similarity of this gene to other bHLH genes suggests that it plays an important role in the differentiation of epidermal cells into muscle attachment sites.

scholarly journals Identification of a new family of tissue-specific basic helix-loop-helix proteins with a two-hybrid system.

1995 ◽  
Vol 15 (7) ◽  
pp. 3813-3822 ◽  
Author(s):  
S M Hollenberg ◽  
R Sternglanz ◽  
P F Cheng ◽  
H Weintraub
Keyword(s):  
Bhlh Protein ◽  
Pharyngeal Arches ◽  
Tissue Specific ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
New Family ◽  
Specific Distribution ◽  
Nih 3T3 ◽  
Two Hybrid

With modified two-hybrid technology, we have isolated a member of a new family of basic helix-loop-helix (bHLH) transcription factors. Thing1 (Th1) was identified in a screen of a mouse embryo cDNA library as a partner for the Drosophila E protein daughterless. RNA in situ hybridization and reverse transcriptase-PCR demonstrate a stage- and tissue-specific distribution for the expression of Th1. Although tissue specific, the expression pattern of Th1 is fairly complex. During development, Th1 mRNA is widely expressed in extraembryonic tissues, portions of the heart, autonomic ganglia, the gut, and pharyngeal arches. At embryonic day 7.5 (E7.5), extraembryonic derivatives show robust Th1 expression. By E8.5, expression in the embryonic heart becomes detectable. During the next 2 days of development, the signal also includes gut and pharyngeal arches. Predominant expression at E13.5 is in neural crest derivatives, especially the autonomic nervous system and adrenal medulla. Expression of Th1 persists in the adult, in which it is localized to the smooth muscle cells of the gut. In vitro, Th1 protein recognizes a set of DNA sites that are more degenerate than has been determined for other bHLH factors, indicating a reduced binding specificity. Transient transfection of NIH 3T3 cells with GAL4-Th1 fusions reveals a repression activity mediated by the Th1 bHLH domain. In combination, these properties define Th1 as a new bHLH protein with a unique set of properties.

scholarly journals Displacement of an E-box-binding repressor by basic helix-loop-helix proteins: implications for B-cell specificity of the immunoglobulin heavy-chain enhancer.

1994 ◽  
Vol 14 (9) ◽  
pp. 6153-6163 ◽  
Author(s):  
T Genetta ◽  
D Ruezinsky ◽  
T Kadesch
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Zinc Finger Protein ◽  
Immunoglobulin Heavy Chain ◽  
Bhlh Protein ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
E Box ◽  
Bhlh Proteins

The activity of the immunoglobulin heavy-chain (IgH) enhancer is restricted to B cells, although it binds both B-cell-restricted and ubiquitous transcription factors. Activation of the enhancer in non-B cells upon overexpression of the basic helix-loop-helix (bHLH) protein E2A appears to be mediated not only by the binding of E2A to its cognate E box but also by the resulting displacement of a repressor from that same site. We have identified a "two-handed" zinc finger protein, denoted ZEB, the DNA-binding specificity of which mimics that of the cellular repressor. By employing a derivative E box that binds ZEB but not E2A, we have shown that the repressor is active in B cells and the IgH enhancer is silenced in the absence of binding competition by bHLH proteins. Hence, we propose that a necessary prerequisite of enhancer activity is the B-cell-specific displacement of a ZEB-like repressor by bHLH proteins.

scholarly journals Identification and Characterization of the Basic Helix-Loop-Helix Transcription Factor Family in Pinus massoniana

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1292
Author(s):  
Yu Chen ◽  
Peihuang Zhu ◽  
Fan Wu ◽  
Xiaofeng Wang ◽  
Jinfeng Zhang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Pinus Massoniana ◽  
Pcr Analysis ◽  
Bhlh Protein ◽  
Transcription Factor Family ◽  
Masson Pine ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Bhlh Genes ◽  
Bhlh Transcription Factors

The basic helix-loop-helix (bHLH) protein transcription factor family is the most widely distributed transcription factor family in eukaryotes. Members of this family play important roles in secondary metabolic biosynthesis, signal transduction, and plant resistance. Research on the bHLH family in animals is more extensive than that in plants, and members of the family in plants are classified according to the classification criteria for those in animals. To date, no research on the bHLH gene family in Pinus massoniana (Masson pine) has been reported. In this study, we identified 88 bHLH genes from four transcriptomes of Masson pine and performed bioinformatics analysis. These genes were divided into 10 groups in total. RT-PCR analysis revealed that the expression levels of the six genes increased under abiotic stress and hormone treatments. These findings will facilitate further studies on the functions of bHLH transcription factors.

scholarly journals The Drosophila Basic Helix-Loop-Helix Protein DIMMED Directly Activates PHM, a Gene Encoding a Neuropeptide-Amidating Enzyme

2007 ◽  
Vol 28 (1) ◽  
pp. 410-421 ◽  
Author(s):  
Dongkook Park ◽  
Orie T. Shafer ◽  
Stacie P. Shepherd ◽  
Hyunsuk Suh ◽  
Jennifer S. Trigg ◽  
...  
Keyword(s):  
Cell Fate ◽  
Transcriptional Activation ◽  
Regulatory Region ◽  
Total Activity ◽  
Bhlh Protein ◽  
Hek 293 ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
E Boxes

ABSTRACT The basic helix-loop-helix (bHLH) protein DIMMED (DIMM) supports the differentiation of secretory properties in numerous peptidergic cells of Drosophila melanogaster. DIMM is coexpressed with diverse amidated neuropeptides and with the amidating enzyme peptidylglycine α-hydroxylating monooxygenase (PHM) in approximately 300 cells of the late embryo. Here we confirm that DIMM has transcription factor activity in transfected HEK 293 cells and that the PHM gene is a direct target. The mammalian DIMM orthologue MIST1 also transactivated the PHM gene. DIMM activity was dependent on the basic region of the protein and on the sequences of three E-box sites within PHM's first intron; the sites make different contributions to the total activity. These data suggest a model whereby the three E boxes interact cooperatively and independently to produce high PHM transcriptional activation. This DIMM-controlled PHM regulatory region displayed similar properties in vivo. Spatially, its expression mirrored that of the DIMM protein, and its activity was largely dependent on dimm. Further, in vivo expression was highly dependent on the sequences of the same three E boxes. This study supports the hypothesis that DIMM is a master regulator of a peptidergic cell fate in Drosophila and provides a detailed transcriptional mechanism of DIMM action on a defined target gene.

SPATULA, a gene that controls development of carpel margin tissues in Arabidopsis, encodes a bHLH protein

Development ◽  
2001 ◽  
Vol 128 (7) ◽  
pp. 1089-1098 ◽  
Author(s):  
M.G. Heisler ◽  
A. Atkinson ◽  
Y.H. Bylstra ◽  
R. Walsh ◽  
D.R. Smyth
Keyword(s):  
Apical Meristem ◽  
Peripheral Zone ◽  
Bhlh Protein ◽  
Floral Organogenesis ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Control Growth ◽  
Dehiscence Zone ◽  
Carpel Development ◽  
Additional Role

Studies involving mutants of the gene SPATULA indicate that it promotes the growth of carpel margins and of pollen tract tissues derived from them. We show that it encodes a new member of the basic-helix-loop-helix family of transcription factors. SPATULA is expressed in marginal and pollen tract tissues throughout their development confirming its role in regulating their growth. It is also expressed in many other tissues where it may act redundantly to control growth, including the peripheral zone of the shoot apical meristem, and specific tissues within leaves, petals, stamens and roots. Expression in the stomium, funiculus and valve dehiscence zone indicates an additional role in abscission. SPATULA expression does not require the function of the other carpel development genes CRABS CLAW and AGAMOUS, although its expression is repressed in first whorl organs by the A function gene APETALA2. Further, we have shown that disruptions to gynoecial pattern formation seen in ettin mutants can largely be attributed to ectopic SPATULA action. ETTIN's role seems to be to negatively regulate SPATULA expression in abaxial regions of the developing gynoecium. SPATULA is the first basic-helix-loop-helix gene in plants known to play a role in floral organogenesis.

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