OBJECTIVEA novel bHLH-like gene, designated SmbHLH1, was isolated from Salvia miltiorrhiza, in order to identify a bHLH gene in related to danshinone biosysnthesis.

METHODSmbHLH1 was isolated by RT-PCR,and Semi-quantitative RT-PCR was used to detect the gene expression level.

RESULTThe full length of SmbHLH1 cDNA has an open reading frame of 999 bp. The deduced amino acid sequence of SmbHLH1 has 332 amino acid residues which forms a 36 kDa polypeptide with a calculated pI of 5.4. SmbHLH1 gene was expressed at high level in root, but low level in stem, leaf and flower of S. miltiorrhiza. The transcripts of SmbHLH1 was suppressed when the plants were treated with exogenous MeJA, Yeast + Ag+. The transcripts of SmbHLH1 constitutively accumulated in response to exogenous ABA and low concentration of salicylic acid.

CONCLUSIONSmbHLH is a new member of the S. miltiorrhiza bHLH family, and its possible roles in brassinosteriods signaling responses.

Basic Helix-Loop-Helix Transcription Factors ; genetics ; physiology ; Cloning, Molecular ; Plant Proteins ; genetics ; physiology ; Salvia miltiorrhiza ; genetics

Iron is one of the essential mineral micronutrients for plants. Low concentrations of effective iron in soil can easily increase risk of plant iron deficiency. Several members of bHLH transcription factors family participate in the response to iron deficiency and play an important role in iron regulation of plants. In order to better understand the mechanism of iron deficiency response, an overview of the structure, classification, function and regulatory mechanism of bHLH transcription factors was given in this review as well as signaling pathway triggered by iron deficiency. It will provide theoretical basis and design strategies for cultivating iron deficiency tolerant or iron-rich crops using bHLH transcription factors.
Arabidopsis ; genetics ; metabolism ; Basic Helix-Loop-Helix Transcription Factors ; genetics ; metabolism ; Gene Expression Regulation, Plant ; Iron ; deficiency ; Signal Transduction ; physiology

Atoh1 gene encodes a helix-loop-helix transcription factor which is involved in the generation and differentiation of mammalian auditory hair cells and supporting cells, and regulation of the proliferation of cochlear cells, therefore plays an important role in the pathogenesis and recovery of sensorineural deafness. This study reviews the progress of the Atoh1 gene in hair cell regeneration, with the aim of providing a reference for the study of hair cell regeneration gene therapy for sensorineural deafness.
Animals ; Humans ; Basic Helix-Loop-Helix Transcription Factors/genetics* ; Hair Cells, Auditory/physiology* ; Transcription Factors ; Hearing Loss, Sensorineural ; Cell Differentiation ; Deafness ; Regeneration/genetics* ; Mammals

BACKGROUNDFolic acid is very important for embryonic development and dihydrofolate reductase is one of the key enzymes in the process of folic acid performing its biological function. Therefore, the dysfunction of dihydrofolate reductase can inhibit the function of folic acid and finally cause the developmental malformations. In this study, we observed the abnormal cardiac phenotypes in dihydrofolate reductase (DHFR) gene knock-down zebrafish embryos, investigated the effect of DHFR on the expression of heart and neural crest derivatives expressed transcript 2 (HAND2) and explored the possible mechanism of DHFR knock-down inducing zebrafish cardiac malformations.

METHODSMorpholino oligonucleotides were microinjected into fertilized eggs to knock down the functions of DHFR or HAND2. Full length of HAND2 mRNA which was transcribed in vitro was microinjected into fertilized eggs to overexpress HAND2. The cardiac morphologies, the heart rates and the ventricular shortening fraction were observed and recorded under the microscope at 48 hours post fertilization. Whole-mount in situ hybridization and real-time PCR were performed to detect HAND2 expression.

RESULTSDHFR or HAND2 knock-down caused the cardiac malformation in zebrafish. The expression of HAND2 was obviously reduced in DHFR knock-down embryos (P < 0.05). Microinjecting HAND2 mRNA into fertilized eggs can induce HAND2 overexpression. HAND2 overexpression rescued the cardiac malformation phenotypes of DHFR knock-down embryos.

CONCLUSIONSDHFR plays a crucial role in cardiac development. The down-regulation of HAND2 caused by DHFR knock-down is the possible mechanism of DHFR knock-down inducing the cardiac malformation.

Animals ; Basic Helix-Loop-Helix Transcription Factors ; genetics ; physiology ; Female ; Heart ; embryology ; Heart Defects, Congenital ; etiology ; Tetrahydrofolate Dehydrogenase ; genetics ; physiology ; Zebrafish ; Zebrafish Proteins ; genetics ; physiology

The protein encoded by gene Nhlh2 (nescient helix-loop-helix 2, also known as HEN2 or NSCL2) is a new member of basic helix-loop-helix (bHLH) transcription factor family and is specifically expressed in nervous system, especially in neuroendocrine tissue. The homologous genes of Nhlh2 have been found in many eukaryotic organisms such as chicken, mouse, rat, cattle, and human. The functional researches of Nhlh2 are mainly focused on neuroendocrine system, retina development, and tumors. Some preliminary results have been obtained in the investigation of molecular regulation mechanism. This article summarizes the recent research advances in Nhlh2.
Animals ; Basic Helix-Loop-Helix Transcription Factors ; biosynthesis ; physiology ; Humans ; Neoplasms ; metabolism ; Nervous System ; metabolism ; Neurosecretory Systems ; metabolism ; Retina ; growth & development ; metabolism ; Species Specificity

More than 80% of all cases of deafness are related to the death or degeneration of cochlear hair cells and the associated spiral ganglion neurons, and a lack of regeneration of these cells leads to permanent hearing loss. Therefore, the regeneration of lost hair cells is an important goal for the treatment of deafness. Atoh1 is a basic helix-loop-helix (bHLH) transcription factor that is critical in both the development and regeneration of cochlear hair cells. Atoh1 is transcriptionally regulated by several signaling pathways, including Notch and Wnt signalings. At the post-translational level, it is regulated through the ubiquitin-proteasome pathway. In vitro and in vivo studies have revealed that manipulation of these signaling pathways not only controls development, but also leads to the regeneration of cochlear hair cells after damage. Recent progress toward understanding the signaling networks involved in hair cell development and regeneration has led to the development of new strategies to replace lost hair cells. This review focuses on our current understanding of the signaling pathways that regulate Atoh1 in the cochlea.
Basic Helix-Loop-Helix Transcription Factors/physiology* ; Cell Differentiation ; Cochlea/physiology* ; Hair Cells, Auditory/physiology* ; Hearing Loss/etiology* ; Humans ; Proteasome Endopeptidase Complex/physiology* ; Signal Transduction/physiology* ; Transcription Factors/physiology* ; Ubiquitin/metabolism* ; Wnt Signaling Pathway ; beta Catenin/physiology*

The sleep-wake cycle displays a characteristic 24-hour periodicity, providing an opportunity to dissect the endogenous circadian clock through the study of aberrant behaviour. This article surveys the properties of circadian clocks, with emphasis on mammals. Information was obtained from searches of peer-reviewed literature in the PUBMED database. Features that are highlighted include the known molecular components of clocks, their entrainment by external time cues and the output pathways used by clocks to regulate metabolism and behaviour. A review of human circadian rhythm sleep disorders follows, including recent discoveries of their genetic basis. The article concludes with a discussion of future approaches to the study of human circadian biology and sleep-wake behaviour.
ARNTL Transcription Factors ; Animals ; Basic Helix-Loop-Helix Transcription Factors ; physiology ; CLOCK Proteins ; Circadian Rhythm ; genetics ; physiology ; Humans ; Neurons, Afferent ; physiology ; Neurons, Efferent ; physiology ; Polymorphism, Single Nucleotide ; Sleep Disorders, Circadian Rhythm ; genetics ; physiopathology ; Suprachiasmatic Nucleus ; cytology ; physiology ; Trans-Activators ; physiology

OBJECTIVETo study the changes of Hes-1, the target gene of Notch signaling pathway, and its relationship with airway inflammation and remodeling in a rat model of asthma.

METHODSForty-eight rats were randomly divided into an asthma group and a control group. The rats in the asthma group were sensitized and challenged by ovalbumin (OVA), and normal saline was used in the control group. Two groups were further divided into 3 subgroups according to time points after challenging, i.e. 4 weeks, 8 weeks and 12 weeks (n=8 rats each). Pathological changes of lungs were observed by light microscopy and the thickness of bronchial smooth muscle layer (Wam) was measured. The levels of IL-4 and INF-γ in rat serum and bronchoalveolar lavage fluids (BALF) were measured using ELISA. Expression levels of Hes-1 protein and mRNA were determined by immunohistochemistry and quantitative real-time PCR respectively.

RESULTSTogether with the extension of challenging, the Wam of rats in the asthma group increased, a decrease of INF-γ level and an increase of IL-4 level in serum and BALF were also observed, and the differences were statistically significant compared with those in the corresponding control group (P<0.05). Hes-1 protein and mRNA levels also increased gradually after OVA challenging and were higher than those in the control group (P<0.05). The levels of Hes-1 protein and mRNA were positively correlated with Wam and IL-4 in serum and BALF, but were inversely correlated with INF-γ in serum and BALF (P<0.05).

CONCLUSIONSLevels of Hes-1 protein and mRNA increased, which were closely related with the levels of airway inflammatory factors and remodeling of airway smooth muscle. Hes-1 may play an important role in the pathogenesis of asthma.

Airway Remodeling ; Animals ; Asthma ; etiology ; Basic Helix-Loop-Helix Transcription Factors ; analysis ; genetics ; physiology ; Disease Models, Animal ; Homeodomain Proteins ; analysis ; genetics ; physiology ; Interferon-gamma ; analysis ; Interleukin-4 ; analysis ; Male ; Rats ; Rats, Sprague-Dawley ; Transcription Factor HES-1

Animals ; Basic Helix-Loop-Helix Transcription Factors ; physiology ; Chronic Disease ; Humans ; Hypoxia ; complications ; Hypoxia-Inducible Factor 1 ; physiology ; Kidney ; metabolism ; Kidney Diseases ; etiology ; Oxidative Stress ; Procollagen-Proline Dioxygenase ; physiology

Low density lipoprotein receptor (LDLR) plays an important role in the cholesterol homeostasis. We examined the possible circadian regulation of LDLR and mechanism(s) underlying it. In mice, blood glucose and plasma triglyceride, total and high density lipoprotein cholesterol varied distinctively throughout a day. In addition, LDLR mRNA oscillated in the liver in a functional clock-dependent manner. Accordingly, analysis of human LDLR promoter sequence revealed three putative E-boxes, raising the possible regulation of LDLR expression by E-box-binding transcription factors. To test this possibility, human LDLR promoter reporter constructs were transfected into HepG2 cells and the effects of CLOCK/BMAL1, Hes1, and Hes6 expression were analyzed. It was found that positive circadian transcription factor complex CLOCK/BMAL1 upregulated human LDLR promoter activity in a serum-independent manner, while Hes family members Hes1 and Hes6 downregulated it only under serum-depleted conditions. Both effects were mapped to proximal promoter region of human LDLR, where mutation or deletion of well-known sterol regulatory element (SRE) abolished only the repressive effect of Hes1. Interestingly, hes6 and hes1 mRNA oscillated in an anti-phasic manner in the wild-type but not in the per1-/-per2-/- mouse. Comparative analysis of mouse, rat and human hes6 genes revealed that three E-boxes are conserved among three species. Transfection and site-directed mutagenesis studies with hes6 reporter constructs confirmed that the third E-box in the exon IV is functionally induced by CLOCK/BMAL1. Taken together, these results suggest that LDLR expression is under circadian control involving CLOCK/BMAL1 and Hes family members Hes1 and Hes6.
ARNTL Transcription Factors/physiology ; Animals ; Base Sequence ; Basic Helix-Loop-Helix Transcription Factors/*genetics/metabolism/physiology ; CLOCK Proteins/physiology ; Cholesterol/blood ; *Circadian Rhythm ; E-Box Elements ; Exons ; *Gene Expression Regulation ; Hep G2 Cells ; Homeodomain Proteins/*genetics/metabolism/physiology ; Homeostasis ; Humans ; Liver/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; *Promoter Regions, Genetic ; Receptors, LDL/*genetics/metabolism ; Repressor Proteins/*genetics/metabolism/physiology ; Transcription, Genetic