Naphthalimide Fluorescent Skeleton for Facile and Accurate Quantification of Glutathione.

Glutathione (GSH), the most prevalent nonprotein thiol in biological systems, acts as both an antioxidant to manipulate intracellular redox homeostasis and a nucleophile to detoxify xenobiotics. The fluctuation of GSH is closely related to the pathogenesis of diverse diseases. This work reports the construction of a nucleophilic aromatic substitution-type probe library based on the naphthalimide skeleton. After an initial evaluation, the compound R13 was identified as a highly efficient GSH fluorescent probe. Further studies demonstrate that R13 could readily quantify GSH in cells and tissues via a straightforward fluorometric assay with a comparable accuracy to the results from the HPLC. We then used R13 to quantify the content of GSH in mouse livers after X-ray irradiation, revealing that irradiation-induced oxidative stress leads to the increase of oxidized GSH (GSSG) and depletion of GSH. In addition, probe R13 was also applied to investigate the alteration of the GSH level in the Parkinson's mouse brains, showing a decrease of GSH and an increase of GSSG in Parkinson's mouse brains. The convenience of the probe in quantifying GSH in biological samples facilitates further understanding of the fluctuation of the GSH/GSSG ratio in diseases.

Three-dimensional Culture of Human Airway Epithelium in Matrigel for Evaluation of Human Rhinovirus C and Bocavirus Infections.

OBJECTIVE: Newly identified human rhinovirus C (HRV-C) and human bocavirus (HBoV) cannot propagate in vitro in traditional cell culture models; thus obtaining knowledge about these viruses and developing related vaccines are difficult. Therefore, it is necessary to develop a novel platform for the propagation of these types of viruses. METHODS: A platform for culturing human airway epithelia in a three-dimensional (3D) pattern using Matrigel as scaffold was developed. The features of 3D culture were identified by immunochemical staining and transmission electron microscopy. Nucleic acid levels of HRV-C and HBoV in 3D cells at designated time points were quantitated by real-time polymerase chain reaction (PCR). Levels of cytokines, whose secretion was induced by the viruses, were measured by ELISA. RESULTS: Properties of bronchial-like tissues, such as the expression of biomarkers CK5, ZO-1, and PCK, and the development of cilium-like protuberances indicative of the human respiration tract, were observed in 3D-cultured human airway epithelial (HAE) cultures, but not in monolayer-cultured cells. Nucleic acid levels of HRV-C and HBoV and levels of virus-induced cytokines were also measured using the 3D culture system. CONCLUSION: Our data provide a preliminary indication that the 3D culture model of primary epithelia using a Matrigel scaffold in vitro can be used to propagate HRV-C and HBoV.

Irradiation Response of Adipose-derived Stem Cells under Three-dimensional Culture Condition.

OBJECTIVE: Adipose tissue distributes widely in human body. The irradiation response of the adipose cells in vivo remains to be investigated. In this study we investigated irradiation response of adipose-derived stem cells (ASCs) under three-dimensional culture condition. METHODS: ASCs were isolated and cultured in low attachment dishes to form three-dimensional (3D) spheres in vitro. The neuronal differentiation potential and stem-liked characteristics was monitored by using immunofluoresence staining and flow cytometry in monolayer and 3D culture. To investigate the irradiation sensitivity of 3D sphere culture, the fraction of colony survival and micronucleus were detected in monolayer and 3D culture. Soft agar assays were performed for measuring malignant transformation for the irradiated monolayer and 3D culture. RESULTS: The 3D cultured ASCs had higher differentiation potential and an higher stem-like cell percentage. The 3D cultures were more radioresistant after either high linear energy transfer (LET) carbon ion beam or low LET X-ray irradiation compared with the monolayer cell. The ASCs' potential of cellular transformation was lower after irradiation by soft agar assay. CONCLUSION: These findings suggest that adipose tissue cell are relatively genomic stable and resistant to genotoxic stress.

Cardiac glycosides from Digitalis lanata and their cytotoxic activities.

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities. In this study, fifteen CGs including three new ones (1-3) were isolated from Digitalis lanata Ehrh. Their structures were elucidated by HRESIMS, NMR spectroscopic methods, including homonuclear and heteronuclear coupling constant analysis, and acid-catalyzed hydrolysis and derivatization analysis of the sugar chain. The cytotoxic activities of these CGs were evaluated against three human cancer cell lines (A549, HeLa and MCF-7 cell lines), and all of them showed strong activities at nanomolar scale. The flow cytometric analysis indicated that compound 1 induced cell cycle arrest in the G2/M phase. Transcriptome analysis revealed a panel of possible targets for compound 1. RT-PCR and western blot experiments showed that 1 significantly inhibited the expression of vasohibin-2 (VASH2). Moreover, compound 1 restrained angiogenesis in a concentration-dependent manner in the chick embryo chorioallantoic membrane (CAM) model.

Menin regulates the function of hematopoietic stem cells and lymphoid progenitors.

Men1 is a tumor suppressor gene mutated in endocrine neoplasms. Besides its endocrine role, the Men1 gene product menin interacts with the mixed lineage leukemia (MLL) protein, a histone H3 lysine 4 methyltransferase. Although menin and MLL fusion proteins cooperate to activate Homeobox (Hox) gene expression during transformation, little is known about the normal hematopoietic functions of menin. Here, we studied hematopoiesis after Men1 ablation. Menin loss modestly impaired blood neutrophil, lymphocyte, and platelet counts. Without hematopoietic stress, multilineage and myelo-erythroid bone marrow progenitor numbers were preserved, while B lymphoid progenitors were decreased. In contrast, competitive transplantation revealed a marked functional defect of long-term hematopoietic stem cells (HSC) in the absence of menin, despite normal initial homing of progenitors to the bone marrow. HoxA9 gene expression was only modestly decreased in menin-deficient HSCs. These observations reveal a novel and essential role for menin in HSC homeostasis that was most apparent during situations of hematopoietic recovery, suggesting that menin regulates molecular pathways that are essential during the adaptive HSC response to stress.

Meso-scale Discovery Assay Detects the Changes of Plasma Cytokine Levels in Mice after Low or High LET Ionizing Irradiation.

OBJECTIVE: To obtain precise data on the changes in the levels of 29 cytokines in mice after high or low linear energy transfer (LET) irradiation and to develop an accurate model of radiation exposure based on the cytokine levels after irradiation. METHODS: Plasma samples harvested from mice at different time points after carbon-ion or X-ray irradiation were analyzed using meso-scale discovery (MSD), a high-throughput and sensitive electrochemiluminescence measurement technique. Dose estimation equations were set up using multiple linear regression analysis. RESULTS: The relative levels of IL-6 at 1 h, IL-5 and IL-6 at 24 h, and IL-5, IL-6 and IL-15 at 7 d after irradiation with two intensities increased dose-dependently. The minimum measured levels of IL-5, IL-6 and IL-15 were up to 4.0076 pg/mL, 16.4538 pg/mL and 0.4150 pg/mL, respectively. In addition, dose estimation models were established and verified. CONCLUSIONS: The MSD assay can provide more accurate data regarding the changes in the levels of the cytokines IL-5, IL-6 and IL-15. These cytokines could meet the essential criteria for radiosensitive biomarkers and can be used as radiation indicators. Our prediction models can conveniently and accurately estimate the exposure dose in irradiated organism.

Mutation of tumor suppressor gene Men1 acutely enhances proliferation of pancreatic islet cells.

Multiple endocrine neoplasia type 1 (MEN1), an inherited tumor syndrome affecting endocrine organs including pancreatic islets, results from mutation of the tumor suppressor gene Men1 that encodes protein menin. Although menin is known to be involved in regulating cell proliferation in vitro, it is not clear how menin regulates cell cycle and whether mutation of Men1 acutely promotes pancreatic islet cell proliferation in vivo. Here we show that excision of the floxed Men1 in mouse embryonic fibroblasts (MEF) accelerates G(0)/G(1) to S phase entry. This accelerated S-phase entry is accompanied by increased cyclin-dependent kinase 2 (CDK2) activity as well as decreased expression of CDK inhibitors p18(Ink4c) and p27(Kip1). Moreover, Men1 excision results in decreased expression of p18(Ink4c) and p27(Kip1) in the pancreas. Furthermore, complementation of menin-null cells with wild-type menin represses S-phase entry. To extend the role of menin in repressing cell cycle in cultured cells to in vivo pancreatic islets, we generated a system in which floxed Men1 alleles can be excised in a temporally controllable manner. As early as 7 days following Men1 excision, pancreatic islet cells display increased proliferation, leading to detectable enlargement of pancreatic islets 14 days after Men1 excision. These observations are consistent with the notion that an acute effect of Men1 mutation is accelerated S-phase entry and enhanced cell proliferation in pancreatic islets. Together, these results suggest a molecular mechanism whereby menin suppresses MEN1 tumorigenesis at least partly through repression of G(0)/G(1) to S transition.

Targeted gene expression in the chicken eye by in ovo electroporation.

PURPOSE: The chicken embryo lens is a classical model system for developmental and cell biology studies. To understand the molecular mechanisms that underlie the morphological changes that occur during lens development, it is important to develop an effective gene transfer method that permits the analysis of gene functions in vivo. In ovo electroporation has been successfully used for introducing DNA into neural and mesenchymal tissues of chicken embryos. In this study, we explored the possibility of using this technique to manipulate gene expression in lens epithelial and fiber cells, as well as in other cells of the chicken eye. METHODS: Two DNA constructs were used in this study. pCAX contains a chicken beta-actin promoter fused to the CMV IE enhancer to drive enhanced green fluorescent protein (EGFP) expression. pMES-cNf2 uses the same chimeric promoter to drive the expression of the chicken neurofibromatosis 2 (cNf2) and EGFP proteins in the same cell. Plasmid DNA was injected into the lumen of the lens vesicle in chicken embryos at stage 15. For corneal epithelial and retinal cell electroporation, DNA was placed near the surface ectoderm in the eye region or injected into the vitreous cavity, respectively. Electroporation was performed with one electrode above the eye and the other underneath the head of the embryo. Chicken embryos were harvested at different time points for EGFP expression analysis by immunohistochemistry. 5-bromo-2'-deoxyuridine (BrdU) incorporation assays were used to evaluate the effects of cNf2 on lens epithelial cell proliferation. RESULTS: A strong EGFP signal can be detected in lens cells 4 h after electroporation. The transfected cells maintain high levels of EGFP expression for at least 5 days. Overexpressing cNf2 in lens epithelial cells significantly inhibits cell proliferation. Ectopic expression of EGFP in corneal epithelial and retinal cells was also achieved by in ovo electroporation. CONCLUSIONS: We have demonstrated that exogenous DNA can be effectively introduced into lens, corneal and retinal cells in the living embryo by in ovo electroporation. In comparison to viral infection and transgenic mouse approaches, in ovo electroporation offers an easier and quicker way to manipulate gene expression during embryonic development. This technique will be a useful tool for exploring the molecular mechanisms of lens and eye development.

Synthesis and structure-activity relationships of N-methyl-5,6,7-trimethoxylindoles as novel antimitotic and vascular disrupting agents.

Several new series of 5,6,7-trimethoxyindole derivatives were synthesized and their structure-activity relationships (SARs) were studied. Some of these compounds exhibited strong antiproliferative activities in the submicromolar range. N-Methyl-5,6,7-trimethoxylindoles 21 and 31 displayed the highest antiproliferative activities, with IC50 values ranging from 22 to 125 nM in four human cancer cell lines and activated human umbilical vein endothelial cells (HUVECs). In addition to vascular disrupting activity verified by in vitro assays, compounds 21 and 31 displayed much higher selectivity for activated HUVECs versus quiescent HUVECs than those of colchicine and combretastatinA-4. The polymerization of cancer cell tubulin was inhibited and the cell cycle was arrested in the G2/M phase after treatment with 21 and 31. It was showed that 21 disrupted tumor vasculature by use of in vivo assay. Our results suggest that these two new compounds we synthesized may become the promising leads for the development of vascular disrupting agents.

Using in ovo electroporation to transfect cells in avian somites.

INTRODUCTIONIn ovo electroporation is an efficient approach for manipulating gene expression in multiple tissues of the chicken embryo, which greatly facilitates functional analysis of the role of specific genes during development. A successful protocol to deliver plasmid DNA into a specific tissue has to meet three basic criteria: high efficiency of transfection, low mortality of embryos, and localization of transfected cells. In this protocol, we describe an in ovo electroporation procedure for targeting muscle precursor cells in the lateral dermomyotome and axial skeletal precursor cells in the sclerotome of the somites of stage 15 chicken embryos. At this stage, the microinjection of DNA solution into individual somites is relatively easy, and the orientation of the electrodes directs the negatively charged DNA into the target tissues. The range of electrical current used is adjusted to maximize the transfection but minimize the mortality of the embryos.

Cdx4 and menin co-regulate Hoxa9 expression in hematopoietic cells.

BACKGROUND: Transcription factor Cdx4 and transcriptional coregulator menin are essential for Hoxa9 expression and normal hematopoiesis. However, the precise mechanism underlying Hoxa9 regulation is not clear. METHODS AND FINDINGS: Here, we show that the expression level of Hoxa9 is correlated with the location of increased trimethylated histone 3 lysine 4 (H3K4M3). The active and repressive histone modifications co-exist along the Hoxa9 regulatory region. We further demonstrate that both Cdx4 and menin bind to the same regulatory region at the Hoxa9 locus in vivo, and co-activate the reporter gene driven by the Hoxa9 cis-elements that contain Cdx4 binding sites. Ablation of menin abrogates Cdx4 access to the chromatin target and significantly reduces both active and repressive histone H3 modifications in the Hoxa9 locus. CONCLUSION: These results suggest a functional link among Cdx4, menin and histone modifications in Hoxa9 regulation in hematopoietic cells.

The tumor suppressor menin regulates hematopoiesis and myeloid transformation by influencing Hox gene expression.

Menin is the product of the tumor suppressor gene Men1 that is mutated in the inherited tumor syndrome multiple endocrine neoplasia type 1 (MEN1). Menin has been shown to interact with SET-1 domain-containing histone 3 lysine 4 (H3K4) methyltransferases including mixed lineage leukemia proteins to regulate homeobox (Hox) gene expression in vitro. Using conditional Men1 knockout mice, we have investigated the requirement for menin in hematopoiesis and myeloid transformation. Men1 excision causes reduction of Hoxa9 expression, colony formation by hematopoietic progenitors, and the peripheral white blood cell count. Menin directly activates Hoxa9 expression, at least in part, by binding to the Hoxa9 locus, facilitating methylation of H3K4, and recruiting the methylated H3K4 binding protein chd1 to the locus. Consistent with signaling downstream of menin, ectopic expression of both Hoxa9 and Meis1 rescues colony formation defects in Men1-excised bone marrow. Moreover, Men1 excision also suppresses proliferation of leukemogenic mixed lineage leukemia-AF9 fusion-protein-transformed myeloid cells and Hoxa9 expression. These studies uncover an important role for menin in both normal hematopoiesis and myeloid transformation and provide a mechanistic understanding of menin's function in these processes that may be used for therapy.

Developmental expression and function of Bmp4 in spermatogenesis and in maintaining epididymal integrity.

Bone morphogenetic proteins (BMPs) play essential roles in many aspects of developmental biology. We have previously shown that Bmp7, Bmp8a, and Bmp8b of the 60A class of Bmp genes have additive effects in spermatogenesis and in maintaining the epididymal integrity of the caput and caudal regions. Here we report that Bmp4 of the Dpp class has a unique expression pattern in the developing testis and epididymis. Bmp4 heterozygous males on a largely C57BL/6 background show compromised fertility due to degeneration of germ cells, reduced sperm counts, and decreased sperm motility. More interestingly, some of these males show extensive degeneration of the epididymal epithelium in the corpus region, rather than in the caput and cauda regions as for Bmp7 and Bmp8 mutants. Thus, these genetic data reveal a region-specific requirement of different classes of BMPs for epididymal epithelium to survive and have significant implications on male reproductive health and perhaps birth control.