Homogeneous detection of viral nucleic acid via selective recognition proximity ligation and signal amplification with T7 transcription and CRISPR/Cas12a system.

The synthetic biology has employed the synthetic gene networks through engineering to construct various functions in biological systems. However, the use of gene circuits to create sensors for detecting low-abundance targets has been limited due to the lack of signal amplification strategies beyond direct output of detection signals. To address this issue, we introduce a novel method utilizing Selective Recognition Proximity Ligation and signal amplification with T7 Transcription and CRISPR/Cas12a system (SRPL-TraCs), which permits the incorporation of cell-free gene circuits with signal amplification and enables the construction of high-order cascade signal amplification strategy to detect biomarkers in homogeneous systems. Specifically, the SRPL-TraCs utilizes selective recognition proximity ligation with high-fidelity T4 DNA ligase and generates a unique crRNA via T7 transcription, along with target-activated Cas12a/crRNA system to achieve excellent specificity for HIV-1 DNA. With this straightforward synthetic biology-based method, the proposed SRPL-TraCs has the potential to detect numerous other interesting targets beyond the nucleic acids.

PTEN inhibitor bisperoxovanadium protects against noise-induced hearing loss.

Studies have shown that phosphatase and tensin homolog deleted on chromosome ten (PTEN) participates in the regulation of cochlear hair cell survival. Bisperoxovanadium protects against neurodegeneration by inhibiting PTEN expression. However, whether bisperoxovanadium can protect against noise-induced hearing loss and the underlying mechanism remains unclear. In this study, we established a mouse model of noise-induced hearing loss by exposure to 105 dB sound for 2 hours. We found that PTEN expression was increased in the organ of Corti, including outer hair cells, inner hair cells, and lateral wall tissues. Intraperitoneal administration of bisperoxovanadium decreased the auditory threshold and the loss of cochlear hair cells and inner hair cell ribbons. In addition, noise exposure decreased p-PI3K and p-Akt levels. Bisperoxovanadium preconditioning or PTEN knockdown upregulated the activity of PI3K-Akt. Bisperoxovanadium also prevented H2O2-induced hair cell death by reducing mitochondrial reactive oxygen species generation in cochlear explants. These findings suggest that bisperoxovanadium reduces noise-induced hearing injury and reduces cochlear hair cell loss.

Beyond the fluorescence labelling of novel nitrogen-doped silicon quantum dots: the reducing agent and stabilizer for preparing hybrid nanoparticles and antibacterial applications.

Silicon quantum dots (SiQDs) have fully demonstrated their applicability in light of their fluorescence. The extension of their applications to other fields, especially considering their excellent biocompatibility, would be more appealing. Herein, a kind of versatile nitrogen-doped silicon quantum dot (N-SiQD) was facilely synthesized via a one-pot hydrothermal method with 3-aminopropyltrimethoxysilane and tetraethylpentylamine as sources. The N-SiQDs were used as a probe for bacterial imaging owing to their good fluorescence properties, stability and biocompatibility. Besides, owing to N doping rendering the N-SiQDs stronger reducibility and Au affinity, the N-SiQDs displayed unique reduction capability, and were attempted as a reducing agent and stabilizer for the synthesis of the nanocomposite, i.e. N-SiQDs stabilized Au nanoparticles (N-SiQDs-AuNPs), under mild conditions. The N-SiQDs-AuNPs showed superior catalytic performance to citric-AuNPs due to the synergistical catalytic effect. In addition, the N-SiQDs exhibited good antibacterial properties against Gram-positive (S. aureus) and Gram-negative bacteria (E. coli) without obvious negative influence on the cells, particularly avoiding the use of any other external stimulation. This study may open a new avenue to use SiQDs for the synthesis of nanocomposites and other biomedicine applications beyond as a fluorescent probe.

Au3+ -Functionalized UiO-67 Metal-Organic Framework Nanoparticles: O2•- and •OH Generating Nanozymes and Their Antibacterial Functions.

The synthesis and characterization of Au3+ -modified UiO-67 metal-organic framework nanoparticles, Au3+ -NMOFs, are described. The Au3+ -NMOFs reveal dual oxidase-like and peroxidase-like activities and act as an active catalyst for the catalyzed generation of O2•- under aerobic conditions or •OH in the presence of H2 O2 . The two reactive oxygen species (ROS) agents O2•- and •OH are cooperatively formed by Au3+ -NMOFs under aerobic conditions, and in the presence of H2 O2. The Au3+ -NMOFs are applied as an effective catalyst for the generation ROS agents for antibacterial and wound healing applications. Effective antibacterial cell death and inhibition of cell proliferation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial colonies are demonstrated in the presence of the Au3+ -NMOFs. In addition, in vivo experiments demonstrate effective wound healing of mice wounds infected by S. aureus, treated by the Au3+ -NMOFs.

Global Transcriptional Analyses of the Wnt-Induced Development of Neural Stem Cells from Human Pluripotent Stem Cells.

The differentiation of human pluripotent stem cells (hPSCs) to neural stem cells (NSCs) is the key initial event in neurogenesis and is thought to be dependent on the family of Wnt growth factors, their receptors and signaling proteins. The delineation of the transcriptional pathways that mediate Wnt-induced hPSCs to NSCs differentiation is vital for understanding the global genomic mechanisms of the development of NSCs and, potentially, the creation of new protocols in regenerative medicine. To understand the genomic mechanism of Wnt signaling during NSCs development, we treated hPSCs with Wnt activator (CHIR-99021) and leukemia inhibitory factor (LIF) in a chemically defined medium (N2B27) to induce NSCs, referred to as CLNSCs. The CLNSCs were subcultured for more than 40 passages in vitro; were positive for AP staining; expressed neural progenitor markers such as NESTIN, PAX6, SOX2, and SOX1; and were able to differentiate into three neural lineage cells: neurons, astrocytes, and oligodendrocytes in vitro. Our transcriptome analyses revealed that the Wnt and Hedgehog signaling pathways regulate hPSCs cell fate decisions for neural lineages and maintain the self-renewal of CLNSCs. One interesting network could be the deregulation of the Wnt/ß-catenin signaling pathway in CLNSCs via the downregulation of c-MYC, which may promote exit from pluripotency and neural differentiation. The Wnt-induced spinal markers HOXA1-4, HOXA7, HOXB1-4, and HOXC4 were increased, however, the brain markers FOXG1 and OTX2, were absent in the CLNSCs, indicating that CLNSCs have partial spinal cord properties. Finally, a CLNSC simple culture condition, when applied to hPSCs, supports the generation of NSCs, and provides a new and efficient cell model with which to untangle the mechanisms during neurogenesis.

Long Noncoding RNA H19 Participates in the Regulation of Adipose-Derived Stem Cells Cartilage Differentiation.

Adipose-derived stem cells (ADSCs) are multipotent and have received increasing attention for their applications in medicine. Cell-based therapies are optimal for diseases with loss or damage to tissues or organs. ADSCs and bone marrow mesenchymal stem cells (BMSCs) can differentiate into many cell lineages. Because of their advantages in accessibility and volume, ADSCs are regarded as a desirable alternative to BMSCs. In this study, we focused on the chondrocytic differentiation potential of ADSCs and the underlying mechanism. We found that the long noncoding RNA H19 plays an important role in this process. Overexpression of H19 in ADSCs induced differentiation towards chondrocytes. H19 is abundantly expressed during embryonic development and downregulated after birth, implying its regulatory role in determining cell fate. However, in our experiments, H19 exerted its regulatory function during cartilage differentiation of ADSCs through competing miRNA regulation of STAT2.

Decreased expression of TERT correlated with postnatal cochlear development and proliferation reduction of cochlear progenitor cells.

Cochlear progenitor cells are considered as one of the best candidates for hair cell regeneration, thus, the regulation of cochlear progenitor cell proliferation has become a focus in this field. Several genes expressed in the inner ear during postnatal development have been demonstrated to be involved in maintaining the proliferative potential of progenitor cells, but the mechanism for regulating the proliferation and differentiation of cochlear progenitor cells remains poorly understood. Telomerase reverse transcriptase (TERT) has rate limiting telomerase activity and the overexpression of TERT has been shown to promote cell proliferation in series of cell lines. The aim of the present study was to evaluate the expression of TERT in the postnatal development of the cochlea and progenitor cells. The results demonstrated that TERT was expressed in the basilar membranes during the first postnatal week. In vitro, TERT expression in progenitor cells reached a maximum at day 4 after culture and decreased as the culture time prolonged or the cell passage number increased. These results led us to hypothesize that TERT may be involved in the development of the cochlea and in maintaining the proliferation ability of progenitor cells.

Minocycline attenuates noise-induced hearing loss in rats.

Noise-induced hearing loss (NIHL) is a serious health concern and prevention of hair cell death or therapeutic intervention at the early stage of NIHL is critical to preserve hearing. Minocycline is a semi-synthetic derivative of tetracycline and has been shown to have otoprotective effects in ototoxic drug-induced hearing impairment, however, whether minocycline can protect against NIHL has not been investigated. The present study demonstrated elevated ABR (auditory brainstem response) thresholds and outer hair cell loss following traumatic noise exposure, which was mitigated by intraperitoneal administration of minocycline (45mg/kg/d) for 5 consecutive days. In conclusion, the present study demonstrated that minocycline, a clinically approved drug with a good safety profile, can attenuate NIHL in rats and may potentially be used for treatment of hearing loss in clinic.

Combinatorial enzymatic digestion with thermolysin and collagenase type I improved the isolation and culture effects of hair cell progenitors from rat cochleae.

The high incidence of hearing loss in human combined with the lack of hair cell regeneration in mammalian cochleae had got the attention to manipulate stem/progenitor cells to participate in hair cell regeneration for years. Cochlear progenitor cells are considered as the best candidate for hair cell regeneration. However, there is not any effective and feasible way to separate hair cell progenitors from rat cochleae, yet. In this study, we tried to isolate single epithelial cells from rat basilar membrane by combinatorial enzymatic digestion with thermolysin and collagenase type I. The results showed that the harvested single cells gave rise to otospheres with features of stem cells and could be induced to differentiate into hair cells. Significantly, more otospheres of epithelial origin were obtained by digesting with thermolysin and collagenase type I. The combinatorial enzymatic digestion would be a potential method for hair cell progenitor isolation and culture with broad applications.

Apoptosis-inducing factor and calpain upregulation in glutamate-induced injury of rat spiral ganglion neurons.

Spiral ganglion neuron (SGN) damage and apoptosis can lead to noise-induced hearing loss, age-associated hearing loss and, in certain cases, auditory neuropathy. The apoptosis-inducing factor (AIF)-associated pathway may be important in this process. The present study aimed to investigate the expression levels of AIF and calpain in damaged SGNs. Glutamate (Glu) perfusion and cell culture in different concentrations of Glu were performed to damage the SGNs of Sprague-Dawley (SD) rats, with saline water used as a control Different concentrations (5, 10, 20 and 40 mM) of Glu were injected into the cochlear tympanic canal of 18 SD rats, and 10, 20 and 40 mM Glu were added to SGN cultures. Auditory brainstem responses (ABR) were measured prior to and 2 days following the injection of Glu. Immunofluorescent staining was used to detect the SGN damage and the expression levels of AIF and calpain in vivo and in in vitro. Transmission electron microscopy (TEM) was used to measure cell apoptosis and reverse transcription-quantitative polymerase chain reaction was used to analyse the gene expression levels of AIF and calpain in the damaged SGNs. The TEM identified mitochondrial vacuolisation, swelling of the SGN and heterochromatin formation. Injection of Glu reduced the number of SGNs and induced apoptosis. AIF was observed to translocate into the nuclei of the SGNs in the 20 and 40 mM Glu groups, and the expression levels of AIF and calpain were markedly upregulated in the modiolus of the Glu-damaged SGNs. The upregulation of AIF and calpain may be important in the process of SGN damage and apoptosis.

Calpain inhibitor PD150606 attenuates glutamate induced spiral ganglion neuron apoptosis through apoptosis inducing factor pathway in vitro.

OBJECTIVE: This research aimed to investigate whether glutamate induced spiral ganglion neurons (SGNs) apoptosis through apoptosis inducing factor (AIF) pathway. And verify whether PD150606, a calpain inhibitor could prevent apoptosis by inhibiting cleaving and releasing AIF in mitochondrion. METHODS: SGNs of postnatal days 0-3 were harvested and cultured in dishes. 20 mM Glu, the caspase inhibitor Z-VAD-FMK and calpain inhibitor PD150606 were added into cultured dishes separately. We used optical microscope and immunofluoresence staining to observe cell morphology and AIF distribution, RT-PCR and Westernblot to analyse AIF and calpain expression in SGNs. TUNEL assay was used to test cell apoptosis. RESULTS: Cell morphology and nuclear translocation of AIF were altered in SGNs by 20 mM Glu treated in vitro. The axon of SGN shortened, more apoptosis SGN were observed and the expression of AIF and calpain were up-regulated in Glu-treated group than the normal one (P<0.05). The same experiments were conducted in 20 mM+PD150606 treated group and 20 mM+Z-VAD-FMK group. Obviously AIF were located from cytoplasm to the nuclear and the expressions of AIF and calpain were down-regulated by PD150606 (P<0.05). Positive cells in TUNEL staining decreased after PD150606 treating. However, Z-VAD-FMK had no influence on AIF, calpain expression or cell apoptosis. CONCLUSION: The AIF-related apoptosis pathway is involved in the process of Glu-induced SGN injury. Furthermore, the inhibition of calpain can prevent AIF from releasing the nuclear or inducing SGN apoptosis.