scholarly journals Transcriptional synergy between LIM-homeodomain proteins and basic helix-loop-helix proteins: the LIM2 domain determines specificity.

1997 ◽  
Vol 17 (7) ◽  
pp. 3488-3496 ◽  
Author(s):  
J D Johnson ◽  
W Zhang ◽  
A Rudnick ◽  
W J Rutter ◽  
M S German
Keyword(s):  
Bhlh Protein ◽  
Homeodomain Protein ◽  
Cell Type ◽  
Homeodomain Proteins ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Lim Domains ◽  
Insulin Promoter ◽  
Physical Interactions ◽  
Lim Homeodomain

LIM-homeodomain proteins direct cellular differentiation by activating transcription of cell-type-specific genes, but this activation requires cooperation with other nuclear factors. The LIM-homeodomain protein Lmx1 cooperates with the basic helix-loop-helix (bHLH) protein E47/Pan-1 to activate the insulin promoter in transfected fibroblasts. In this study, we show that two proteins originally called Lmx1 are the closely related products of two distinct vertebrate genes, Lmx1.1 and Lmx1.2. We have used yeast genetic systems to delineate the functional domains of the Lmx1 proteins and to characterize the physical interactions between Lmx1 proteins and E47/Pan-1 that produce synergistic transcriptional activation. The LIM domains of the Lmx1 proteins, and particularly the second LIM domain, mediate both specific physical interactions and transcriptional synergy with E47/Pan-1. The LIM domains of the LIM-homeodomain protein Isl-1, which cannot mediate transcriptional synergy with E47/Pan-1, do not interact with E47/Pan-1. In vitro studies demonstrate that the Lmx1.1 LIM2 domain interacts specifically with the bHLH domain of E47/Pan-1. These studies provide the basis for a model of the assembly of LIM-homeodomain-containing complexes on DNA elements that direct cell-type-restricted transcription in differentiated tissues.

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 Structural Basis for Partial Redundancy in a Class of Transcription Factors, the LIM Homeodomain Proteins, in Neural Cell Type Specification

2011 ◽  
Vol 286 (50) ◽  
pp. 42971-42980 ◽  
Author(s):  
Morgan S. Gadd ◽  
Mugdha Bhati ◽  
Cy M. Jeffries ◽  
David B. Langley ◽  
Jill Trewhella ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Neural Cell ◽  
Structural Basis ◽  
Cell Type ◽  
Homeodomain Proteins ◽  
Partial Redundancy ◽  
Type Specification ◽  
Lim Homeodomain

Scleraxis: a basic helix-loop-helix protein that prefigures skeletal formation during mouse embryogenesis

Development ◽  
1995 ◽  
Vol 121 (4) ◽  
pp. 1099-1110 ◽  
Author(s):  
P. Cserjesi ◽  
D. Brown ◽  
K.L. Ligon ◽  
G.E. Lyons ◽  
N.G. Copeland ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Expression Pattern ◽  
Consensus Sequence ◽  
Cell Types ◽  
Cell Type ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
E Box ◽  
Cell Type Specific ◽  
Bhlh Proteins

Members of the basic helix-loop-helix (bHLH) family of transcription factors have been shown to regulate growth and differentiation of numerous cell types. Cell-type-specific bHLH proteins typically form heterodimers with ubiquitous bHLH proteins, such as E12, and bind a DNA consensus sequence known as an E-box. We used the yeast two-hybrid system to screen mouse embryo cDNA libraries for cDNAs encoding novel cell-type-specific bHLH proteins that dimerize with E12. One of the cDNAs isolated encoded a novel bHLH protein, called scleraxis. During mouse embryogenesis, scleraxis transcripts were first detected between day 9.5 and 10.5 post coitum (p.c.) in the sclerotome of the somites and in mesenchymal cells in the body wall and limb buds. Subsequently, scleraxis was expressed at high levels within mesenchymal precursors of the axial and appendicular skeleton and in cranial mesenchyme in advance of chondrogenesis; its expression pattern in these cell types foreshadowed the developing skeleton. Prior to formation of the embryonic cartilaginous skeleton, scleraxis expression declined to low levels. As development proceeded, high levels of scleraxis expression became restricted to regions where cartilage and connective tissue formation take place. Scleraxis bound the E-box consensus sequence as a heterodimer with E12 and activated transcription of a reporter gene linked to its DNA-binding site. The expression pattern, DNA-binding properties and transcriptional activity of scleraxis suggest that it is a regulator of gene expression within mesenchymal cell lineages that give rise to cartilage and connective tissue.

Regulation of Apterous activity inDrosophilawing development

Development ◽  
2001 ◽  
Vol 128 (22) ◽  
pp. 4615-4622 ◽  
Author(s):  
Ulrich Weihe ◽  
Marco Milán ◽  
Stephen M. Cohen
Keyword(s):  
Complex Formation ◽  
Wing Development ◽  
Homeodomain Protein ◽  
Activity Levels ◽  
Present Evidence ◽  
Drosophila Wing ◽  
Lim Domains ◽  
Regulation Of Activity ◽  
Lim Homeodomain

Apterous is a LIM-homeodomain protein that confers dorsal compartment identity in Drosophila wing development. Apterous activity requires formation of a complex with a co-factor, Chip/dLDB. Apterous activity is regulated during wing development by dLMO, which competes with Apterous for complex formation. Here, we present evidence that complex formation between Apterous, Chip and DNA stabilizes Apterous protein in vivo. We also report that a difference in the ability of Chip to bind the LIM domains of Apterous and dLMO contributes to regulation of activity levels in vivo.

scholarly journals Crystallization and diffraction of an Isl1–Ldb1 complex

2012 ◽  
Vol 68 (11) ◽  
pp. 1398-1401 ◽  
Author(s):  
Morgan S. Gadd ◽  
David A. Jacques ◽  
J. Mitchell Guss ◽  
Jacqueline M. Matthews
Keyword(s):  
Unit Cell ◽  
Homeodomain Protein ◽  
Unit Cell Parameters ◽  
Space Group ◽  
Cell Parameters ◽  
Lim Domains ◽  
Intramolecular Complex ◽  
Orthorhombic Crystals ◽  
Peptide Region ◽  
Lim Homeodomain

A stable intramolecular complex comprising the LIM domains of the LIM-homeodomain protein Isl1 tethered to a peptide region of Ldb1 has been engineered, purified and crystallized. The orthorhombic crystals belonged to space groupP2221, with unit-cell parametersa= 57.2,b= 56.7,c= 179.8 Å, and diffracted to 3.10 Å resolution.

scholarly journals Functional analysis of the nuclear LIM domain interactor NLI.

1997 ◽  
Vol 17 (10) ◽  
pp. 5688-5698 ◽  
Author(s):  
L W Jurata ◽  
G N Gill
Keyword(s):  
Transcriptional Activation ◽  
Negative Regulator ◽  
Homeodomain Protein ◽  
Lim Domain ◽  
Transcriptional Responses ◽  
Amino Terminal ◽  
High Affinity ◽  
Lim Domains ◽  
Lim Homeodomain

LIM homeodomain and LIM-only (LMO) transcription factors contain two tandemly arranged Zn2+-binding LIM domains capable of mediating protein-protein interactions. These factors have restricted patterns of expression, are found in invertebrates as well as vertebrates, and are required for cell type specification in a variety of developing tissues. A recently identified, widely expressed protein, NLI, binds with high affinity to the LIM domains of LIM homeodomain and LMO proteins in vitro and in vivo. In this study, a 38-amino-acid fragment of NLI was found to be sufficient for the association of NLI with nuclear LIM domains. In addition, NLI was shown to form high affinity homodimers through the amino-terminal 200 amino acids, but dimerization of NLI was not required for association with the LIM homeodomain protein Lmxl. Chemical cross-linking analysis revealed higher-order complexes containing multiple NLI molecules bound to Lmx1, indicating that dimerization of NLI does not interfere with LIM domain interactions. Additionally, NLI formed complexes with Lmx1 on the rat insulin I promoter and inhibited the LIM domain-dependent synergistic transcriptional activation by Lmx1 and the basic helix-loop-helix protein E47 from the rat insulin I minienhancer. These studies indicate that NLI contains at least two functionally independent domains and may serve as a negative regulator of synergistic transcriptional responses which require direct interaction via LIM domains. Thus, NLI may regulate the transcriptional activity of LIM homeodomain proteins by determining specific partner interactions.

Differential expression of a transcription regulatory factor, the LIM domain only 4 protein Lmo4, in muscle sensory neurons

Development ◽  
2002 ◽  
Vol 129 (21) ◽  
pp. 4879-4889
Author(s):  
Hsiao-Huei Chen ◽  
Joseph W. Yip ◽  
Alexandre F. R. Stewart ◽  
Eric Frank
Keyword(s):  
Differential Expression ◽  
Sensory Neurons ◽  
Molecular Mechanisms ◽  
Neuronal Development ◽  
Expression Patterns ◽  
Cdna Libraries ◽  
Homeodomain Protein ◽  
Lim Domain ◽  
Homeodomain Proteins ◽  
Lim Homeodomain

In the stretch-reflex system, proprioceptive sensory neurons make selective synaptic connections with different subsets of motoneurons, according to the peripheral muscles they supply. To examine the molecular mechanisms that may influence the selection of these synaptic targets, we constructed single-cell cDNA libraries from sensory neurons that innervate antagonist muscles. Differential screening of these libraries identified a transcription regulatory co-factor of the LIM homeodomain proteins, the LIM domain only 4 protein Lmo4, expressed in most adductor but few sartorius sensory neurons. Differential patterns of Lmo4 expression were also seen in sensory neurons supplying three other muscles. A subset of motoneurons also expresses Lmo4 but the pattern of expression is not specific for motor pools. Differential expression of Lmo4 occurs early, as neurons develop their characteristic LIM homeodomain protein expression patterns. Moreover, ablation of limb buds does not block Lmo4 expression, suggesting that an intrinsic program controls the early differential expression of Lmo4. LIM homeodomain proteins are known to regulate several aspects of sensory and motor neuronal development. Our results suggest that Lmo4 may participate in this differentiation by regulating the transcriptional activity of LIM homeodomain proteins.

scholarly journals GATA2-Induced Silencing and LIM-Homeodomain Protein-Induced Activation Are Mediated by a Bi-Functional Response Element in the Rat GnRH Receptor Gene

2013 ◽  
Vol 27 (1) ◽  
pp. 74-91 ◽  
Author(s):  
Anne-Laure Schang ◽  
Anne Granger ◽  
Bruno Quérat ◽  
Christian Bleux ◽  
Joëlle Cohen-Tannoudji ◽  
...  
Keyword(s):  
Cell Fate ◽  
Promoter Activity ◽  
Receptor Gene ◽  
Gnrh Receptor ◽  
Expression Vectors ◽  
Homeodomain Protein ◽  
Homeodomain Proteins ◽  
Enhancer Activity ◽  
Response Element ◽  
Lim Homeodomain

GATA2 transcription factor and LIM homeodomain proteins Islet1 (ISL1) and LIM homeobox 3 (LHX3) are suspected to be involved in gonadotrope cell fate and maintenance. The GnRH receptor gene (Gnrhr), crucial for gonadotrope function, is expressed in the pituitary gland from embryonic day 13.5 onward, well before LH and FSH β-subunits. This expression pattern together with the presence of WGATAR and TAAT motifs in Gnrhr promoter sequences suggests the involvement of early transcription factors in promoter activation. In this study, using a well-characterized transgenic mouse model, GATA2 was found colocalized with Gnrhr promoter activity in the pituitary. Transient transfection of Gnrhr promoter luciferase fusion constructs together with either GATA2 expression vectors or small interfering RNA in gonadotrope cell lines indicated that GATA2, which typically acts as a trans-activator, unexpectedly repressed Gnrhr promoter activity. Using DNA chromatography affinity and EMSA, we demonstrated that GATA2 operates via a response element containing a peculiar palindromic GATA motif that overlaps a critical TAAT motif involved in LHX3/ISL1 trans-activation. Indeed, despite the inhibitory action of GATA2, this element displayed a clear-cut enhancer activity in gonadotrope cells. Chromatin immunoprecipitation assays indicated that GATA2, LHX3, and ISL1 interact with a Gnrhr promoter fragment encompassing this element. The trans-repressive action of GATA2 on Gnrhr promoter activity is likely balanced or even hindered by trans-activating effects of LIM homeodomain proteins via this novel bifunctional LIM/GATA response element. Such a hierarchical interplay may contribute to finely adjust Gnrhr gene expression in gonadotrope cell lineage during pituitary development as well as in the adult animal.

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.

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