Highly Efficient Photoelectrochemical Detection of Cystatin C Based on a Core-Shell MOF Nanocomposite with Biomimetic-Catalysis Amplification.

Cystatin C (CysC) has been proven to be used to diagnose acute kidney injury (AKI) rapidly and sensitively early. Therefore, it is urgent to develop a sensitive, novel, and rapid method for detecting CysC. In this work, a novel photoelectrochemical (PEC) biosensor was designed for ultrasensitive CysC detection. Ti-MOF@DM-LZU1@Au as a photosensitive material was first modified on the ITO electrode surface. Then, Ab1 and CysC were assembled on the electrode via the specific immunoresponse of an antigen and antibody. Lastly, the conjugate Ab2/l-Cys bilayer/l-Cys-hemin/G-quadruplex with self-catalytic enzyme performance, as a signal amplification approach, could further react with CysC and Ab1, which resulted in a stronger photocurrent. As expected, the constructed PEC sensor realized the ultrasensitive detection of CysC, with a detection range of 10 pg/mL to 16 µg/mL and a lower limit of 8.023 pg/mL. The biosensor had excellent repeatability, selectivity, and stability. Moreover, it can provide a new method for the sensitive and rapid detection of other protein molecules in clinical practice.

Photoelectrochemical sensor based on AuNPs@WO3@TpPa-1-COF for quantification of DNA methylation levels.

A "signal-off" photoelectrochemical (PEC) sensing platform has been designed for the ultrasensitive detection of DNA methylation levels and multiple methylated sites. The platform employs tungsten trioxide and TpPa-1-COF loaded by gold nanoparticle (AuNPs@WO3@TpPa-1-COF) composite material as the photoactive component and p-type reduced graphene (rGO) as an efficient quencher. The PEC signal of AuNPs@WO3@TpPa-1-COF composite is effectively quenched in the presence of p-type rGO, because p-type rGO can compete with AuNPs@WO3@TpPa-1-COF to deplete light energy and electron donors. In addition, a hybrid strand reaction (HCR) amplification strategy fixes more target DNA and then combines with rGO-modified anti-5-methylcytosine antibody to facilitate ultrasensitive DNA methylation detection. Under optimal conditions, DNA methylation can be measured within a linear concentration range of 10-14 to 10-8 M, with an exceptionally low detection limit of 0.19 fM (S/N = 3). At the same time, the platform can conduct quantitative determination of multi-site methylation, with the linear equation △I = 44.19LogA + 61.43, and the maximum number of methylation sites is 5. The sensor demonstrates high sensitivity, excellent selectivity, and satisfactory stability. Furthermore, the proposed signal-off PEC strategy was successfully employed to detect DNA methylation in spiked human serum samples, with recoveries ranging from 93.17 to 107.28% and relative standard deviation (RSD) ranging from 1.15 to 5.49%.

A novel photoelectrochemical strategy for sequence-spot bispecific analysis of N6-methyladenosine modification based on proximity ligation-triggered cascade amplification.

N6-methyladenosine (m6A) modification as the most prevalent mammalian RNA internal modification has been considered as the invasive biomarkers in clinical diagnosis and biological mechanism researches. It is still challenged to explore m6A functions due to technical limitations on base- and location-resolved m6A modification. Herein, we firstly proposed a sequence-spot bispecific photoelectrochemical (PEC) strategy based on in situ hybridization mediated proximity ligation assay for m6A RNA characterization with high sensitivity and accuracy. Firstly, the target m6A methylated RNA could be transferred to the exposed cohesive terminus of H1 based on the special self-designed auxiliary proximity ligation assay (PLA) with sequence-spot bispecific recognition. The exposed cohesive terminus of H1 could furtherly trigger the next catalytic hairpin assembly (CHA) amplification and in situ exponential nonlinear hyperbranched hybridization chain reaction for highly sensitive monitoring of m6A methylated RNA. Compared with conventional technologies, the proposed sequence-spot bispecific PEC strategy for m6A methylation of special RNA based on proximity ligation-triggered in situ nHCR performed improved sensitivity and selectivity with a detection limit of 53 fM, providing new insights into highly sensitive monitoring m6A methylation of RNA in bioassay, disease diagnosis and RNA mechanism.

Ultrasensitive photoelectrochemical biosensor for DNA 5-methylcytosine analysis based on co-sensitization strategy combined with bridged DNA nanoprobe.

Altered DNA methylation in the form of 5-methylcytosine (5-mC) patterns is correlated with disease diagnosis, prognosis, and treatment response. Therefore, accurate analysis of 5-mC is of great significance for the diagnosis of diseases. Here, an efficient enhanced photoelectrochemical (PEC) biosensor was designed for the quantitative analysis of DNA 5-mC based on a cascaded energy level aligned co-sensitization strategy coupling with the bridged DNA nanoprobe (BDN). Firstly, Au nanoparticle/graphite phase carbon nitride/titanium dioxide (AuNPs/g-C3N4@TiO2) nanocomposite was synthesized through in situ growth of AuNPs on g-C3N4@TiO2 surface as a matrix to provide a stable background signal. Next, BDN with a high mass transfer rate synthesized from a pair of DNA tetrahedral as nanomechanical handles was used as a capture probe to bind to the target sequence. The polydopamine nanosphere was applied to load with CdTe QDs (PDANS-CdTe QDs) as a photocurrent label of 5-mC antibodies. When the 5-mC existed, a large number of PDANS-Ab-CdTe QDs were introduced to the electrode surface, the formed CdTe QDs/AuNPs/g-C3N4@TiO2 co-sensitive structure could effectively enhance the electron transfer capability and photocurrent response rate due to the effective cascade energy level arrangement, leading to a significantly enhanced photocurrent signal. The proposed PEC biosensor manifested a wide range from 10-17 M to 10-7 M and a detection limit of 2.2 aM. Meanwhile, the excellent performance indicated the practicability of the designed strategy, thus being capable of the clinical diagnosis of 5-mC.

DNA methylation detection and site analysis by using an electrochemical biosensor constructed based on toehold-mediated strand displacement reaction.

DNA methylation has become a novel target for early diagnosis and prognosis of cancer as well as other related diseases. The accurate detection of the methylation sites of specific genes proved to be of great significance. However, the complex biological nature of clinical samples and the detection of low-abundance targets led to higher requirements for the testing technology. It has been found that by virtue of high sensitivity, rapid response, low cost, facile operation and applicability to microanalysis, electrochemical sensors have greatly contributed to the process of clinical diagnosis. In this study, a facile, rapid and highly sensitive electrochemical biosensor based on the peak current change was developed on the basis of high selectivity of toehold and greater efficiency of PNA strand displacement and used for the detection and site analysis of DNA methylation. Moreover, compared with non-methylated DNA sequences, methylated DNA sequences could be readily invaded by PNA probes, thereby resulting in the strand displacement and significant electrical signals. Therefore, methylation of cytosine sites was primarily analyzed based on electrical signals. Strand displacement by the target DNA sequences with different methylated sites can lead to substantial changes of strand displacement efficiency. As a result, the methylation sites can be analyzed on the basis of corresponding peak current response relation. This method has a detection limit of 0.075 pM and does not involve various complicated steps such as bisulfite treatment, enzyme digestion and PCR amplification. Indeed, one detection cycle can be completed in 60 min. The proposed technology might exhibit great potential in early clinical diagnosis and risk assessment of cancers and related diseases.

Calreticulin enhances gastric cancer metastasis by dimethylating H3K9 in the E-cadherin promoter region mediating by G9a.

The latest study shows that gastric cancer (GC) ranked the fifth most common cancer (5.6%) with over 1 million estimated new cases annually and the fourth most common cause of cancer death (7.7%) globally in 2020. Metastasis is the leading cause of GC treatment failure. Therefore, clarifying the regulatory mechanisms for GC metastatic process is necessary. In the current study, we discovered that calreticulin (CALR) was highly expressed in GC tissues and related to lymph node metastasis and patient's terrible prognosis. The introduction of CALR dramatically promoted GC cell migration in vitro and in vivo, while the repression of CALR got the opposite effects. Cell migration is a functional consequence of the epithelial-mesenchymal transition (EMT) and is related to adhesion of cells. Additionally, we observed that CALR inhibition or overexpression regulated the expression of EMT markers (E-cadherin, ZO-1, Snail, N-cadherin, and ZEB1) and cellular adhesive moleculars (Fibronectin, integrin ß1and MMP2). Mechanistically, our data indicated that CALR could mediate DNA methylation of E-cadherin promoter by interacting with G9a, a major euchromatin methyltransferase responsible for methylation of histone H3 on lysine 9(H3K9me2) and recruiting G9a to the E-cadherin promoter. Knockdown of G9a in CALR overexpressing models restored E-cadherin expression and blocked the stimulatory effects of CALR on GC cell migration. Taken together, these findings not only reveal critical roles of CALR medicated GC metastasis but also provide novel treatment strategies for GC.

3D matrixed DNA self-nanocatalyzer as electrochemical sensitizers for ultrasensitive investigation of DNA 5-methylcytosine.

DNA methylation plays an important role in a variety of human diseases. Thus, accurately analyze 5-methylcytosine in different DNA segments is of great significance. Herein, we proposed a novel 3D matrixed DNA self-nanocatalyzer via gold nanoparticles (AuNPs) supporting DNA self-hybridization with hemin as biomimetic enzyme and methylene blue (MB) as electrochemical mediator, which was employed as an efficient electrochemical sensitizer for the ultrasensitive bioassay of DNA 5-methylcytosine. Meanwhile, the AuNPs, graphitic carbon nitride (g-C3N4) and reduced graphene oxide (rGO) was prepared as AuNPs/g-C3N4@rGO nanocomposites to coat on the electrode surface to immobilize the capture hairpin DNA (CH). In the presence of target DNA with 5-methylcytosine, the target DNA could hybridize with CH via the hyperstable triple-helix formation. Based on the specific biorecognition between biotin and streptavidin and immune recognition between anti-5-methylcytosine antibodies and 5-methylcytosine sites on the target DNA, the 3D matrixed DNA self-nanocatalyzer could be captured onto the electrode surface to generate an amplified electrochemical signal related to the concentration of 5-methylcytosine. Under the optimal conditions, the proposed strategy performed a linear range from 10-17 M to 10-8 M with a detection limit of 8.6 aM. Remarkably, this strategy could be expanded easily to various biomarkers, including protein, DNA, phosphorylation and glycosylation, providing a promising strategy for clinical diagnosis and mechanism investigation of various diseases.

A sensitive electrochemical strategy via multiple amplification reactions for the detection of E. coli O157: H7.

The sensitive and efficient strategy remains a central challenge for early diagnosis of pathogenic bacteria. Herein, an ultrasensitive electrochemical biosensor was proposed based on the multiple amplification strategy via the 3D DNA walker, rolling circle amplification (RCA) and hybridization chain reaction (HCR) for the accurate detection of Escherichiacoli O157:H7 (E. coli O157:H7). Firstly, the target sequence extracted from E. coli O157:H7 was transformed and amplified by the DNA walker firstly. Subsequently, a large number of transformed nucleic acid sequences were amplified by the RCA reaction. And then, the progress of HCR was triggered by every fragment in RCA products to form a long double-stranded DNA sequence to immobilize electrochemical indicators, generating a significantly enhanced electrochemical signal. As expected, a high sensitivity with a detection limit of 7 CFU/mL was achieved based on the proposed multiple amplification strategy, which is superior to most current methods for E. coli O157: H7 assay. The multiple amplification strategy could be readily expanded for the detection of various pathogenic bacteria, providing a new approach for early diagnosis of pathogenic microorganisms or other diseases.

Electrochemical and Optical Biosensing Strategies for DNA Methylation Analysis.

DNA methylation is considered as a crucial part of epigenetic modifications and a popular research topic in recent decades. It usually occurs with a methyl group adding to the fifth carbon atom of cytosine while the base sequence of DNA remains unchanged. DNA methylation has significant influences on maintaining cell functions, genetic imprinting, embryonic development and tumorigenesis procedures and hence the analysis of DNA methylation is of great medical significance. With the development of analytical techniques and further research on DNA methylation, numerous DNA methylation detection strategies based on biosensing technology have been developed to fulfill various study requirements. This article reviewed the development of electrochemistry and optical biosensing analysis of DNA methylation in recent years; in addition, we also reviewed some recent advances in the detection of DNA methylation using new techniques, such as nanopore biosensors, and highlighted the key technical and biological challenges involved in these methods. We hope this paper will provide useful information for the selection and establishment of analysis of DNA methylation.

A novel fluorescent biosensor based on dendritic DNA nanostructure in combination with ligase reaction for ultrasensitive detection of DNA methylation.

BACKGROUND: DNA methylation detection is indispensable for the diagnosis and prognosis of various diseases including malignancies. Hence, it is crucial to develop a simple, sensitive, and specific detection strategy. METHODS: A novel fluorescent biosensor was developed based on a simple dual signal amplification strategy using functional dendritic DNA nanostructure and signal-enriching polystyrene microbeads in combination with ligase detection reaction (LDR). Dendritic DNA self-assembled from Y-DNA and X-DNA through enzyme-free DNA catalysis of a hairpin structure, which was prevented from unwinding at high temperature by adding psoralen. Then dendritic DNA polymer labeled with fluorescent dye Cy5 was ligated with reporter probe into a conjugate. Avidin-labeled polystyrene microbeads were specifically bound to biotin-labeled capture probe, and hybridized with target sequence and dendritic DNA. LDR was triggered by adding Taq ligase. When methylated cytosine existed, the capture probe and reporter probe labeled with fluorescent dye perfectly matched the target sequence, forming a stable duplex to generate a fluorescence signal. However, after bisulfite treatment, unmethylated cytosine was converted into uracil, resulting in a single base mismatch. No fluorescence signal was detected due to the absence of duplex. RESULTS: The obtained dendritic DNA polymer had a large volume. This method was time-saving and low-cost. Under the optimal experimental conditions using avidin-labeled polystyrene microbeads, the fluorescence signal was amplified more obviously, and DNA methylation was quantified ultrasensitively and selectively. The detection range of this sensor was 10-15 to 10-7 M, and the limit of detection reached as low as 0.4 fM. The constructed biosensor was also successfully used to analyze actual samples. CONCLUSION: This strategy has ultrasensitivity and high specificity for DNA methylation quantification, without requiring complex processes such as PCR and enzymatic digestion, which is thus of great value in tumor diagnosis and biomedical research.

Recent Progress in Microfluidic Models of the Blood-Brain Barrier.

The blood-brain barrier (BBB) is a critical physical and chemical barrier that maintains brain homeostasis. Researchers in academia and industry are highly motivated to develop experimental models that can accurately mimic the physiological characteristics of the BBB. Microfluidic systems, which manipulate fluids at the micrometer scale, are ideal tools for simulating the BBB microenvironment. In this review, we summarized the progress in the design and evaluation of microfluidic in vitro BBB models, including advances in chip materials, porous membranes, the use of endothelial cells, the importance of shear stress, the detection specific markers to monitor tight junction formation and integrity, measurements of TEER and permeability. We also pointed out several shortcomings of the current microfluidic models. The purpose of this paper is to let the readers understand the characteristics of different types of model design, and select appropriate design parameters according to the research needs, so as to obtain the best experimental results. We believe that the microfluidics BBB models will play an important role in neuroscience and pharmaceutical research.

An electrochemical DNA biosensor analytic technique for identifying DNA methylation specific sites and quantify DNA methylation level.

We herein developed a novel electrochemical biosensor to detect DNA methylation level, and to quantitatively analyze multiple methylated sites. Graphene oxide was modified with anti-5-methylcytosine antibody to specifically bind CpG methylation sites, and horseradish peroxidase (HRP)-labeled IgG secondary antibody was bound to the former antibody. In buffer containing H2O2 and hydroquinone, HRP-IgG catalyzed the oxidation of hydroquinone into benzoquinone over H2O2, thereby generating electrochemical reduction signals. The number of 5-methylcytosine was directly proportional to current signal, thereby allowing accurate quantification of methylation level. We also analyzed monomethylated target sequences with different sites. After different methylated sites were captured by the probe, the steric hindrance differences between -CH3 hydrophobic sphere and the electrode surface were induced. The peak current decreased with reducing distance from the electrode surface, so DNA methylation sites were identified by measuring corresponding peak current responses. With a low detection limit (1 fM), this DNA biosensor was suitable for ultrasensitive DNA methylation detection. The linear detection range was 10-15 M to 10-8 M. Meanwhile, this method had high specificity, stability and repeatability, thus being widely applicable to the clinical detection of DNA methylation.

Electrochemical Biosensor for DNA Methylation Detection through Hybridization Chain-Amplified Reaction Coupled with a Tetrahedral DNA Nanostructure.

DNA methylation is a key factor in the pathogenesis of gene expression diseases or malignancies. Thus, it has become a significant biomarker for the diagnosis and prognosis of these diseases. In this paper, we designed an ultrasensitive and specific electrochemical biosensor for DNA methylation detection. The platform consisted of stem-loop-tetrahedron composite DNA probes anchoring at a Au nanoparticle-coated gold electrode, a restriction enzyme digestion of HpaII, and signal amplification procedures including electrodeposition of Au nanoparticles, hybridization chain reaction, and horseradish peroxidase enzymatic catalysis. Under optimal conditions, the design showed a broad dynamic range from 1 aM to 1 pM and a detection limit of about 0.93 aM. The approach also showed ideal specificity, repeatability, and stability. The recovery test demonstrated that the design is a promising platform for DNA methylation detection under clinical circumstances and could meet the need for cancer diagnosis.

An electrochemical strategy with tetrahedron rolling circle amplification for ultrasensitive detection of DNA methylation.

Sensitive and specific detection of DNA methylation in genomic DNA is imperative for rapid epigenetic evaluations. Here, a novel sensitive electrochemical strategy was developed for ultrasensitive detection of DNA methylation in genomic DNA via padlock probe primer generating rolling circle amplification (RCA). Typically, after bisulfite treatment of methylated DNA, the methylation-specific linear padlock is only circularized in the presence of methylated DNA and subsequently serves as a template containing a DNA tetrahedron for RCA. The DNA tetrahedron is utilized as a nanocarrier that can be immobilized on a gold electrode to generate RCA product to load hemin, an iron-containing porphyrin with chlorine, forming the G-quadruplex as a horseradish peroxidase like DNAzyme, which reduces methylene blue (MB) in the presence of H2O2 to yield a distinct current signal. Using the developed DNAzyme with the RCA signal amplification strategy, the DNA biosensor can achieve a detection limit as low as 0.1 fM for the ultrasensitive electrochemical detection of methylated DNA sequence with a detection range from 10-15 M to 10-9 M. At the same time, the satisfactory specificity, reproducibility, stability and recovery performances indicated its satisfied potentials for clinical diagnosis. Most importantly, this method can be further applied to analyse other genomic DNA also.

A Highly Sensitive Detection System based on Proximity-dependent Hybridization with Computer-aided Affinity Maturation of a scFv Antibody.

The hepatitis B virus (HBV) infection is a critical health problem worldwide, and HBV preS1 is an important biomarker for monitoring HBV infection. Previously, we found that a murine monoclonal antibody, mAb-D8, targets the preS1 (aa91-107) fragment of HBV. To improve its performance, we prepared the single-chain variable region of mAb-D8 (scFvD8) and constructed the three-dimensional structure of the scFvD8-preS1 (aa91-107) complex by computer modelling. The affinity of scFvD8 was markedly increased by the introduction of mutations L96Tyr to Ser and H98Asp to Ser. Furthermore, a highly sensitive immunosensor was designed based on a proximity-dependent hybridization strategy in which the preS1 antigen competitively reacts with an antibody labelled with DNA, resulting in decreased proximity-dependent hybridization and increased electrochemical signal from the Fc fragment, which can be used for the quantisation of preS1. The results showed a wide detection range from 1 pM to 50 pM with a detection limit of 0.1 pM. The sensitivity and specificity of this immunosensor in clinical serum samples were 100% and 96%, respectively. This study provides a novel system based on proximity-dependent hybridization and the scFv antibody fragment for the rapid quantisation of antigens of interest with a high sensitivity.

An Electrochemical Strategy using Multifunctional Nanoconjugates for Efficient Simultaneous Detection of Escherichia coli O157: H7 and Vibrio cholerae O1.

The rapid and accurate quantification of the pathogenic bacteria is extremely critical to decrease the bacterial infections in all areas related to health and safety. We have developed an electrochemical strategy for simultaneous ultrasensitive detection of E. coli O157:H7 and Vibrio cholerae O1. This approach was based on the specific immune recognition of different pathogenic bacteria by multifunctional nanoconjugates and subsequent signal amplification. By employing the proposed biosensor, the concentrations of these pathogenic bacteria could be established on a single interface in a single run with improved sensitivity and accuracy. The successful approach of the simultaneous detection and quantification of two bacteria by an electrochemical biosensor demonstrated here could be readily expanded for the estimation of a variety of other pathogenic bacteria, proteins, and nucleotides. Because of their high sensitivity, electrochemical biosensors may represent a new avenue for early diagnosis of diseases.

Transcription factor ICBP90 regulates the MIF promoter and immune susceptibility locus.

The immunoregulatory cytokine macrophage migration inhibitory factor (MIF) is encoded in a functionally polymorphic locus that is linked to the susceptibility of autoimmune and infectious diseases. The MIF promoter contains a 4-nucleotide microsatellite polymorphism (-794 CATT) that repeats 5 to 8 times in the locus, with greater numbers of repeats associated with higher mRNA levels. Because there is no information about the transcriptional regulation of these common alleles, we used oligonucleotide affinity chromatography and liquid chromatography-mass spectrometry to identify nuclear proteins that interact with the -794 CATT5-8 site. An analysis of monocyte nuclear lysates revealed that the transcription factor ICBP90 (also known as UHRF1) is the major protein interacting with the MIF microsatellite. We found that ICBP90 is essential for MIF transcription from monocytes/macrophages, B and T lymphocytes, and synovial fibroblasts, and TLR-induced MIF transcription is regulated in an ICBP90- and -794 CATT5-8 length-dependent manner. Whole-genome transcription analysis of ICBP90 shRNA-treated rheumatoid synoviocytes uncovered a subset of proinflammatory and immune response genes that overlapped with those regulated by MIF shRNA. In addition, the expression levels of ICBP90 and MIF were correlated in joint synovia from patients with rheumatoid arthritis. These findings identify ICBP90 as a key regulator of MIF transcription and provide functional insight into the regulation of the polymorphic MIF locus.

Real-time monitoring of mycobacterium genomic DNA with target-primed rolling circle amplification by a Au nanoparticle-embedded SPR biosensor.

In this study, we developed a surface plasmon resonance (SPR) DNA biosensor array based on target-primed rolling circle amplification (RCA) for isothermal and rapid detection of two pathogenic mycobacteria, Mycobacterium tuberculosis complex (MTBC) and Mycobacterium avium complex (MAC).The species-specific padlock probe (PLP) was designed to target the sequence in 16S-23S rRNA gene internal transcribed spacer (ITS). After ligation, the circularized PLP could be primed by the target sequence to initial RCA. The RCA performed simultaneously with the cleavage reaction to produce small fragments of single strand DNA which immediately hybridized with the probe immobilized on the sensor chip without denaturation. This process caused SPR angle changes on the chip surface, which made the detection for analysis from the solution achievable, and dynamic real-time RCA monitoring of mycobacterium possible. Besides, Au nanoparticles (AuNPs) were directly assembled onto the surface of the sensor chip via hexanedithiol (HDT) for the enhancement of sensitivity as a label-free detection system. Experimental results show that the signal enhancement by the target-primed RCA together with AuNPs-embedded surface caused at least10-fold increased sensitivity as compared with conventional RCA on bare SPR chip method. Within 40min amplification duration as low as 20amol of synthetic targets and 10(4)CFUmL(-1) of genomic DNA from clinical samples can be detected. The proposed method not only provides a simple design idea for liquid-phase amplification monitoring, but also apply it in clinical pathogen detection, which holds great promise in ultrasensitive bioassay in the future.

A novel electrochemical DNA biosensor based on HRP-mimicking hemin/G-quadruplex wrapped GOx nanocomposites as tag for detection of Escherichia coli O157:H7.

A novel sensitive electrochemical DNA biosensor was developed for amperometric detection of Escherichia coli O157:H7 (E. coli O157:H7). The graphene oxide (GOx) was utilized as nanocarrier to immobilize thionine (Thi) and the Au nanoparticles coated SiO2 nanocomposites (Au-SiO2) by electrostatic adsorption and the adsorption among nanomaterials. Then a large amounts of signal DNA (S2) and G-quadruplex were immobilized on the GOx-Thi-Au@SiO2 nanocomposites. Finally, hemin was intercalated into the G-quadruplex to obtain the hemin/G-quadruplex structure as HRP-mimicking DNAzyme. On the basis of the signal amplification strategy of GOx-Thi-Au@SiO2 nanocomposites and DNAzyme, the developed DNA biosensor could respond to 0.01 nM (S/N=3) with a linear calibration range from 0.02 to 50.0 nM E. coli O157:H7, which could be well accepted for early clinical detection. The studied system provides new opportunities, and might speed up disease diagnosis, treatment and prevention with pathogen.

Mixed lineage leukaemia histone methylases 1 collaborate with ERα to regulate HOXA10 expression in AML.

HOXA10, a homeobox-containing gene involved in definitive haematopoiesis, which implicated in the pathogenesis of AML (acute myeloid leukaemia), has been studied extensively. But the regulatory mechanism that drives HOXA10 expression is still unclear. In the present paper, HOXA10 regulated by MLL1 (mixed lineage leukaemia histone methylase 1) with an epigenetic way has been demonstrated. The HOXA10 promoter contains several EREs (oestrogen response elements), including ERE1 and ERE2, which are close to the transcription start site, and are associated with E2-mediated activation of HOXA10. It has been shown that knockdown of the ERα (oestrogen receptor α) suppresses E2-mediated activation of HOXA10. Similarly, knockdown of MLL1 suppresses activation of HOXA10 and is bound to the ERE of HOXA10 promoter in an E2-dependent manner by forming complex with ERα. Knockdown of ERα affects the E2-dependent binding of MLL1 into HOXA10 EREs, suggesting critical roles of ERα in recruiting MLL on the HOXA10 promoter. More interestingly, the methylation status of histone protein H3K4 (H3 at lysine 4) with E2 is much higher than without E2 treatment in leukaemia cell. On the contrary, the methylation status of HOXA10 promoter with E2 treatment is much lower, which elevate the HOXA10 expression. Moreover, with ERα knockdown, the H3K4 methylation level is also decrease in myeloid cell. Overall, it has been clearly demonstrated that HOXA10 is transcriptionally regulated by MLL1, which, in coordination with ERα, plays a critical role in this process with epigenetic way and suggests a potential anti-E2 treatment of AML.