Quantitative Analysis of Factors Regulating Angiogenesis for Stem Cell Therapy.

(1) Background: The control of angiogenesis is essential in disease treatment. We investigated angiogenesis-promoting or -suppressing factors and their molecular mechanisms. (2) Methods: Angiogenesis from HUVECs was quantitatively analyzed using the Angiogenesis Analysis Kit (Kurabo, Osaka, Japan). Human rAng-1-producing 107-35 CHO cells or mouse DFAT-D1 cells were co-cultured with HUVEC. Antioxidant polyphenols were added to the culture. Gene expression was analyzed by RT-PCR. (3) Results: The addition of rAng-1-producing cells, their culture supernatant, or commercially available rAng-1 showed a promoting effect on angiogenesis. The co-culture of DFAT-D1 cells promoted angiogenesis. Polyphenols showed a dose-dependent inhibitory effect on angiogenesis. Luteolin and quercetin showed remarkable anti-angiogenic effects. The expression of vWF, Flk1, and PECAM-1 was increased by adding rAng-1-producing cell culture supernatant. Polyphenols suppressed these genes. Apigenin and luteolin markedly suppressed α-SMA and Flk1. Resveratrol and quercetin enhanced the expression of PPARγ, and luteolin suppressed the expression of COX-1. The expression of endothelial nitric oxide synthase (eNOS), an oxidative stress-related gene, was slightly increased by luteolin. These results suggest that polyphenols induce ROS reduction. (4) Conclusions: We showed the promoting effect of Ang-1 or DFAT and the suppressing effect of polyphenols on angiogenesis and studied their molecular mechanisms. These results help control angiogenesis in regenerative therapy.

Sec14l3 is specifically expressed in mouse airway ciliated cells.

Airway epithelium is a key component for airway integrity. Previously, we found that expression of the Sec14l3 gene that encodes a 45-kDa secretory protein is inversely associated with the progression of experimentally induced airway inflammation and degeneration/necrosis of alveolar epithelium. In this report, using in situ hybridization we demonstrated that the ciliated cells in mouse lung selectively express Sec14l3 mRNA. In a three-dimensional culture of mouse tracheal epithelial cells, levels of the Sec14l3 mRNA correlated with the differentiation of ciliated cells. Intranasal infection of adult mice with influenza virus resulted in a 20-fold, progressive decrease in Sec14l3 mRNA expression over 10 days post infection. These results enhance the potential value of Sec14l3 as a ciliated epithelial cell-specific biomarker for the progression of airway inflammations such as airway viral infection and asthma.

A cell-based screening method for specifically detecting kinase activity.

No universal approach has been reported for specific monitoring of the catalytic activity of a wide range of kinases in cells. The present study describes an original platform for detecting the autonomous activity of serine/threonine kinases in cells through the introduction of expression vectors encoding modified substrate kinase fusion proteins. The surrogate substrate used consists of the p53 tumor suppressor protein fused with individual kinase domains (Chk1, DYRK3, and Cdk5) at its carboxy-terminal through four tandem Gly-Gly-Gly-Gly-Ser repeats. After transfection into cells, phosphorylation of the p53 moiety could be specifically induced by the catalytic activity of kinases contained in the fusion protein. Moreover, p53 phosphorylation was significantly blocked when a kinase-inactive mutant was used as the fusion partner instead of the active kinase. Using this system, the cell-based evaluation of several Cdk5 inhibitors was demonstrated. Thus, this approach provides a novel platform for the specific, cell-based screening of inhibitors of a wide prospective range of protein kinases and is of tremendous potential for drug discovery efforts.

A robust, target-driven, cell-based assay for checkpoint kinase 1 inhibitors.

Checkpoint kinase 1 (Chk1), a serine/threonine kinase, plays an important role in DNA damage checkpoint control and is an attractive target for cancer treatment. To develop a Chk1-specific cell-based assay, stable clones were established in which Chk1 kinase domain fused at its N-terminus with p53 through 4 tandem repeats of Gly-Gly-Gly-Gly-Ser was expressed in an inducible manner. Chk1 kinase specificity of the phosphorylation of fused p53 was confirmed by the experiments with a kinase-inactive Chk1. Only in the presence of an inducer molecule was phosphorylation of p53 at Ser-15 in the stable clones induced. Furthermore, its assay performance proved acceptable for high-throughput screening applications, judging from the Z' factor values (> 0.77). Finally, the cell-based assay thus established yielded structure-activity relationship data for a small set of test inhibitors of Chk1 within cells. Collectively, these results demonstrate that the established cell-based assay provides a novel and highly sensitive cellular platform for Chk1 inhibitor discovery.

A selective cellular screening assay for B-Raf and c-Raf kinases.

The Ras/Raf signaling pathway has been recognized as an important process in cancer biology. Recently, activating mutations in the BRAF gene were reported to be present in approximately 66% of malignant melanomas as well as other malignancies such as colon cancer. Here, the authors report the development of a B-Raf-specific cellular assay to profile cell-active B-Raf inhibitors. Expression of the active B-Raf mutant (V600E) and the kinase-inactive form of its substrate, MEK1, was regulated by mifepristone, and the catalytic activity of B-Raf was monitored by following MEK1 phosphorylation. Target specificity was ensured because the phosphorylation of MEK1 was significantly inhibited when kinase-inactive B-Raf was used in place of the active kinase. A cellular c-Raf assay was similarly established to monitor the selectivity between B-Raf and c-Raf. Z' factor values were consistently above 0.50 with either kinase, indicating that assay performance was sufficiently robust for use as cellular profiling assays. The authors used this system to demonstrate that the selectivity profile of compounds targeted against B-Raf and c-Raf kinases could be quantitatively determined. This platform provides a quantitative cellular readout for a spectrum of specific inhibitors of B-Raf and c-Raf kinases that is particularly suitable for use in drug discovery.

In vitro biological activity of a novel small-molecule inhibitor of polo-like kinase 1.

Polo-like kinase 1 (PLK1) plays key roles in the regulation of mitotic progression, including mitotic entry, spindle formation, chromosome segregation, and cytokinesis. PLK1 expression and activity are strongly linked to proliferating cells. Many studies have shown that PLK1 expression is elevated in a variety of tumors, and high expression often correlates with poor prognosis. Using a variety of methods, including small-molecule inhibition of PLK1 function and/or activity, apoptosis in cancer cell lines, cell cycle arrest in normal cell lines, and antitumor activity in vivo have been observed. In the present study, we have examined the in vitro biological activity of a novel and selective thiophene benzimidazole ATP-competitive inhibitor of PLK1 and PLK3 (5-(5,6-dimethoxy-1H-benzimidazol-1-yl)-3-{[2-(trifluoromethyl)-benzyl]oxy}thiophene-2-carboxamide, called compound 1). Compound 1 has low nanomolar activity against the PLK1 and PLK3 enzymes and potently inhibits the proliferation of a wide variety of tumor cell lines. In the lung adenocarcinoma cell line NCI-H460, compound 1 induces a transient G(2)-M arrest, mitotic spindle defects, and a multinucleate phenotype resulting in apoptosis, whereas normal human diploid fibroblasts arrest in G(2)-M and show little apoptosis. We also describe a cellular mechanistic assay that was developed to identify potent intracellular inhibitors of PLK1. In addition to its potential as a therapeutic agent for treating cancer, compound 1 is also a useful tool molecule for further investigation of the biological functions of PLK1 and PLK3.

Kinetic properties of tetrodotoxin-sensitive and tetrodotoxin-resistant sodium channel currents in neonatal rat trigeminal ganglion neurons.

The kinetic properties of tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na' channels in acutely dissociated neonatal rat trigeminal ganglion neurons were studied using whole-cell and cell-attached patch-clamp recordings. The time course of TTX-R currents was slower than that of TTX-S currents. Compared with TTX-S currents, TTX-R currents had more positive half-activation and half-inactivation voltages. TTX-R currents recovered from inactivation much faster than TTX-S currents. Cell-attached patch recordings showed that the slope conductance of single TTX-S and TTX-R channels was 14.6 pS and 7.8 pS, respectively. TTX-R channels had longer open-times and more dispersed latent-times than TTX-S channels. The convolution of the first latency distribution with the open-time distribution revealed that the slower time course of TTX-R currents is due to longer open-times and more dispersed latent-times of the TTX-R channels compared with those of the TTX-S channels. These findings suggest that TTX-R Na+ channels in trigeminal ganglion neurons have similar kinetic property to brain TTX-S Na+ channels, but not to structurally homologous cardiac Na+ channels.

Molecular cloning of XTP, a tau-like microtubule-associated protein from Xenopus laevis tadpoles.

The microtubules of the mammalian nervous system are stabilised by several microtubule-associated proteins (MAPs), including the tau and MAP-2 protein families. The most prominent feature of mammalian tau and MAP-2 proteins is a common and highly homologous microtubule-binding region consisting of three or four imperfect tandem repeats. In this paper we report the cloning and characterisation of a Xenopus laevis tau-like protein (XTP) from tadpole tails. This protein encompasses two isoforms of 673 or 644 amino acids with four tandem repeats that are highly homologous to mammalian tau repeats. Both isoforms share a common amino terminal half, whereas the carboxyl terminus downstream of the repeat region is unique for each isoform. Northern blot analysis revealed that both isoforms are preferentially expressed in the tail of X. laevis tadpoles, whereas a shorter version of XTP is expressed in the head. Recombinant proteins of both XTP isoforms were able to bind microtubules. The longest isoform, however, was more effective at promoting tubulin polymerisation, indicating that sequences downstream of the repeat region affect the microtubule assembling capacity. These results demonstrate that tau-like proteins are found in non-mammalian vertebrate species, where they may support the stability of microtubules.

Micromere Differentiation in the Sea Urchin Embryo: Expression of Primary Mesenchyme Cell Specific Antigen during Development: (sea urchin/micromere/primary mesenchyme cell/monoclonal antibody).

The temporal and spatial expression of antigen specific for primary mesenchyme cell (PMC) lineage cells during early development of the sea urchins Hemicentrotus pulcherrimus and Stronglyocentrotus nudus was studied with a monoclonal antibody (P4). P4 was produced by a hybridoma cell line prepared by fusion of myeloma cells and spleen cells from a mouse immunized with cultured spicule-forming cells. Immunofluorescence studies demonstrated that P4 antibody reacted strongly with the surfaces of PMC's and spicule-forming cells of both species. Immunoblot analysis showed that P4 antibody reacted with several proteins including those of 140-kDa, 120-kDa, 53-kDa, 43-kDa, and 41-kDa in H. pulcherrimus and with those of 130-kDa, 110-kDa, 51-kDa, and 43-kDa in S. nudus. These proteins appeared sequentially after the hatching blastula stage. Tunicamycin inhibited the expressions of these P4 antigens as well as spicule formation. Two of the P4-reactive antigens, the 140-kDa and 43-kDa proteins, in H. pulcherrimus were synthesized de novo and shown to be identical to micromere differentiation specific proteins. These results suggest that P4 binds to specific molecules that are important in spicule formation in developing sea urchin embryos.