Identification of NAC Transcription Factors in Suaeda glauca and Their Responses to Salt Stress.

NAC (NAM/ATAF1/2/CUC2) transcription factors regulate plant growth and development and stress responses. Because NAC transcription factors are known to play important roles in the regulation of salt tolerance in many plants, we aimed to explore their roles in the halophyte Suaeda glauca. Based on transcriptome sequencing data, we identified 25 NAC transcription factor gene family members. In a phylogenetic tree analysis with Arabidopsis thaliana NAC transcription factors, the SgNACs were divided into 10 groups. The physicochemical properties and conserved domains of the putative proteins, as well as the transcript profiles of their encoding genes, were determined for the 25 SgNAC genes using bioinformatic methods. Most of the S. glauca NAC genes were upregulated to some extent after 24 h of salt stress, suggesting that they play an important role in regulating the salt tolerance of S. glauca. These findings lay the foundation for further research on the functions and mechanisms of the NAC gene family in S. glauca.

Near-Infrared Fluorescent Furin Probe for Revealing the Role of Furin in Cellular Carcinogenesis and Specific Cancer Imaging.

Furin, an important member in the family of proprotein convertases, is a participant in the activation of various precursor proteins. The expression level of furin stays in a very low range in most normal cells, but elevates with a big margin in many cancer cells. More importantly, furin is closely related to tumor formation and migration. Herein, a furin-activatable near-infrared (NIR) fluorescent probe (HD-F) was first developed that allowed for specific, sensitive detection and imaging of furin both in vitro and in vivo. HD-F consists of a classical NIR fluorophore (HD), a furin-particular polypeptide sequence RVRR, and a self-eliminating linker. Without the interaction with furin, no noticeable fluorescence enhancement was detected, even over 3 days, demonstrating the excellent stability of HD-F. Upon conversion by furin, there was a distinct signal increase around 708 nm. It has achieved assay and visualization of endogenous furin in various cells, tumor tissues, and tumor-bearing mouse models. Importantly, HD-F is well-suited for monitoring the change of furin expression level in the process of hypoxia-inducible factor-1 stabilized by CoCl2. Moreover, HD-F could visualize the divergence in the expression level of furin between normal and cancer cells, indicating its potential in specific cancer imaging. Thus, this novel probe is able to serve as a potential tackle for better understanding of the intrinsic link between a hypoxic physiological environment and cellular carcinogenesis and predicting cancer in preclinical applications.

In Situ Localization of Enzyme Activity in Live Cells by a Molecular Probe Releasing a Precipitating Fluorochrome.

Current enzyme-responsive, fluorogenic probes fail to provide in situ information because the released fluorophores tend to diffuse away from the reaction sites. The problem of diffusive signal dilution can be addressed by designing a probe that upon enzyme conversion releases a fluorophore that precipitates. An excited-state intramolecular proton transfer (ESIPT)-based solid-state fluorophore HTPQ was developed that is strictly insoluble in water and emits intense fluorescence in the solid state, with λex/em =410/550 nm, thus making it far better suited to use with a commercial confocal microscope. HTPQ was further utilized in the design of an enzyme-responsive, fluorogenic probe (HTPQA), targeting alkaline phosphatase (ALP) as a model enzyme. HTPQA makes possible diffusion-resistant in situ detection of endogenous ALP in live cells. It was also employed in the visualizing of different levels of ALP in osteosarcoma cells and tissue, thus demonstrating its interest for the diagnosis of this type of cancer.

Engineering dithiobenzoic acid lactone-decorated Si-rhodamine as a highly selective near-infrared HOCl fluorescent probe for imaging drug-induced acute nephrotoxicity.

A highly selective lysosome-targeting NIR fluorescent probe (Lyso-SiR-2S) for HOCl was constructed based on Si-rhodamine B spirodithiolactone. This probe was very effectively employed to sense HOCl produced in various living cells and to visualize fluctuations of endogenous HOCl resulting from GEN-induced acute kidney injury in vivo for the first time.

In vivo imaging of alkaline phosphatase in tumor-bearing mouse model by a promising near-infrared fluorescent probe.

Alkaline phosphatase (ALP), one of the important hydrolases, is associated with the progress of many diseases as a well-defined biomarker. Fluorescence imaging of ALP in living organisms is of great importance for biological studies. However, in vivo detection of ALP remains a great challenge because current fluorescent probes show short excitation and emission wavelength, which are not desired for in vivo fluorescence imaging. Herein we reported a near-infrared (NIR) fluorescent probe (NALP) for turn-on trapping of ALP activity in living cancer cells and tumors. NALP was composed of a NIR-emitting fluorophore as a reporter and phosphate as a triggered moiety. Phosphate group was directly tethered to the hydroxyl group of fluorophore, which prohibited the fluorescence. The probe exhibited a high selectivity and remarkable fluorescence turn-on response to ALP in aqueous solutions with a detection limit of 0.28U/L. Benefiting from NIR excitation and emission, high contrast on the imaging signal could be achieved in response to endogenous ALP activity. Impressively, not only we successfully used NALP for imaging of endogenous ALP activity in cancer cells, but also, applied it for fluorescence imaging of ALP in tumor tissues and living tumor xenograft in nude mice for the first time. The probe was expected to be promising tool for practical application in disease diagnosis on the roles of ALP in disease.

A mitochondrial-targeted prodrug for NIR imaging guided and synergetic NIR photodynamic-chemo cancer therapy.

Nontoxic prodrugs, especially activated by tumor microenvironment, are urgently required for reducing the side effects of cancer therapy. And combination of chemo-photodynamic therapy prodrugs show effectively synergetic therapeutic efficiency, however, this goal has not been achieved in a single molecule. In this work, we developed a mitochondrial-targeted prodrug PNPS for near infrared (NIR) fluorescence imaging guided and synergetic chemo-photodynamic precise cancer therapy for the first time. PNPS contains a NIR photosensitizer (NPS) and an anticancer drug 5'-deoxy-5-fluorouridine (5'-DFUR). These two parts are linked and caged through a bisboronate group, displaying no fluorescence and very low cytotoxicity. In the presence of H2O2, the bisboronate group is broken, resulting in activation of NPS for NIR photodynamic therapy and activation of 5'-DFUR for chemotherapy. The activated NPS can also provide a NIR fluorescence signal for monitoring the release of activated drug. Taking advantage of the high H2O2 concentration in cancer cells, PNPS exhibits higher cytotoxicity to cancer cells than normal cells, resulting in lower side effects. In addition, based on its mitochondrial-targeted ability, PNPS exhibits enhanced chemotherapy efficiency compare to free 5'-DFUR. It also demonstrated a remarkably improved and synergistic chemo-photodynamic therapeutic effect for cancer cells. Moreover, PNPS exhibits excellent tumor microenvironment-activated performance when intravenously injected into tumor-bearing nude mice, as demonstrated by in vivo fluorescence imaging. Thus, PNPS is a promising prodrug for cancer therapy based on its tumor microenvironment-activated drug release, synergistic therapeutic effect and "turn-on" NIR imaging guide.