p57KIP2 modulates stress-activated signaling by inhibiting c-Jun NH2-terminal kinase/stress-activated protein Kinase

p57KIP2, a member of the Cip/Kip family of enzymes that inhibit several cyclin-dependent kinases, plays a role in many biological events including cell proliferation, differentiation, apoptosis, tumorigenesis and developmental changes. The human p57KIP2 gene is located in chromosome 11p15.5, a region implicated in sporadic cancers and Beckwith-Wiedemann syndrome. We here report that p57KIP2 physically interacts with and inhibits c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK). The carboxyl-terminal QT domain of p57KIP2 is crucial for the inhibition of JNK/SAPK. Overexpressed p57KIP2 also suppressed UV- and MEKK1-induced apoptotic cell death. p57KIP2 expression during C2C12 myoblast differentiation resulted in repression of the JNK activity stimulated by UV light. Furthermore, UV-stimulated JNK1 activity was higher in mouse embryonic fibroblasts derived from p57-/- mice than in the cells from wild-type mice. Taken together, these findings suggest that p57KIP2 modulates stress-activated signaling by functioning as an endogenous inhibitor of JNK/SAPK.     

Green fluorescent protein-labeled recombinant fluobody for detecting the picloram herbicide

A green fluorescent protein-labeled fluobody was designed to develop a simple immunoassay method for detecting picloram herbicide in an environmental sample. The gfp gene was successfully inserted into the pSJF2 vector harboring the picloram-specific antibody fragment to yield pSJF2GFP. Picloram spiking in an environmental river sample could be indirectly detected by observing the fluorescence intensity value of the gfp-fluobody, exhibiting specific sensitivity to free picloram with an IC50 value of 50 ppb. Using the gfp-fluobody immunoassay avoids the enzyme-substrate reaction for calorimetric detection that is required in an enzyme-linked immunosorbent assay (ELISA).     

Hydrazinocurcumin,a novel synthetic curcumin derivative,is a potent inhibitor of endothelial cell proliferation

Curcumin and some of its derivatives were known as in vivo inhibitors of angiogenesis. In present study, a novel curcumin derivative, named hydrazinocurcumin (HC) was synthesized and examined for its biological activities. HC potently inhibited the proliferation of bovine aortic endothelial cells (BAECs) at a nanomolar concentration (IC(50)=520 nM) without cytotoxicity. In vivo and in vitro angiogenesis experiments showed HC as a new candidate for anti-angiogenic agent.     

The control of mRNA stability in response to extracellular stimuli

Regulated mRNA turnover is a highly important process in control of gene expression. The specific sequence elements in mRNA modulate the stability of different mRNAs, which varies considerably in response to extracellular stimuli. But the mechanistic basis for regulation of mRNA turnover remains nebulous. Recent works indicate that several signaling pathways have been implicated in regulating the decay of specific mRNA and certain ARE binding proteins mediate rapid degradation of the mRNAs. This review provides a current knowledge of diverse extracellular signals contributing to stabilization of short-lived mRNA.     

Inhibition of microsurgical thrombosis by the platelet glycoprotein IIb/IIIa antagonist SR121566A

Despite major improvements in tools and significant refinements of techniques, microsurgical anastomosis still carries a significant risk of failure due to microvascular thrombosis. The key to improving the success of microvascular surgery may lie in the pharmacologic control of thrombus formation. Central to pathologic arterial thrombosis are platelets. Glycoprotein IIb/IIIa is a highly abundant platelet surface receptor that plays a major role in platelet aggregation by binding platelets to each other through the coagulation factor fibrinogen. To explore the ability of antithrombotic agents to prevent microvascular thrombosis, a rabbit ear artery model was used in which a standardized arterial injury results in predictable thrombus formation. This model was used to examine whether SR121566A, a specific and potent glycoprotein IIb/IIIa inhibitor, can successfully prevent microsurgical thrombosis.Using a coded, double-blind experimental design, 20 rabbits (40 arteries) were assigned to four treatment groups: (1) saline injection (n = 10), (2) acetylsalicylic acid 10 mg/kg (n = 10), (3) heparin 0.5 mg/kg bolus with subsequent intermittent boluses of 0.25 mg/kg every 30 minutes (n = 10), and (4) SR121566A 2 mg/kg bolus (n = 10). After vessel damage and clamp release, arteries were assessed for patency at 5, 30, and 120 minutes by the Acland refill test. Coagulation assays, in vivo bleeding times, and ex vivo platelet aggregation studies were also conducted. Scanning electron microscopy was used to examine mural thrombus composition.A significant, fourfold increase in vessel patency following administration of SR121566A over saline control (80 percent versus 20 percent patency, respectively, at 35 minutes after reperfusion, p < 0.01) was noted. This was correlated with marked inhibition of ex vivo platelet aggregation. This antiplatelet treatment did not prolong coagulation assays (mean international normalized ratio: saline, 0.66 +/- 0.04; SR121566A, 0.64 +/- 0.03; mean thromboplastin time: saline, 19.63 +/- 0.67; SR121566A, 17.87 +/- 3.27) and bleeding times (mean bleeding time: saline, 42 +/- 4; SR121566A, 48 +/- 6). Scanning electron microscopy demonstrated extensive platelet and fibrin deposition in control vessel thrombi. In contrast, thrombi from SR121566A-treated vessels demonstrated predominance of fibrin with few platelets when examined under scanning electron microscopy.Administration of SR121566A was associated with a significant increase in vessel patency, without deleterious effects on coagulation assays or bleeding times. The increase in vessel patency was correlated with inhibition of platelet aggregation and decreased platelet deposition, as demonstrated by scanning electron microscopy. Glycoprotein IIb/IIIa antagonists represent a new class of anti-platelet agents that may be suited for inhibiting microsurgical thrombosis. This study supports further investigation into the use of these agents in microsurgery.     

Inhibition of catalase activity by oxidative stress and its relationship to salicylic acid accumulation in plants

The decrease in catalase activity and its relationship to change in salicylic acid content were investigated in rice, wheat, and cucumber seedlings exposed to oxidative stresses. A decrease in chlorophyll fluorescence (F/Fm), measured as an indicator of the oxidative stress, and a drop in catalase activity were observed following treatment with NaCl in all plant seedlings tested . Furthermore, such decreases in F/Fm and catalase activity were also observed under low temperature conditions in both rice cultivars, whereas the degrees of decrease were dependent on their low temperature tolerance . Although the content of salicylic acid increased in rice seedlings stressed by NaCl treatment, it was inversely correlated with the decrease in the catalase activity . Such a relationship between the decrease in catalase activity and increase in salicylic acid content was confirmed with paraquat treatment of the rice seedlings . These results suggested that the fall in catalase activity is a phenomenon occurring in many plant species under oxidative stress and is related to the accumulation of salicylic acid in oxidatively-stressed plants.     

A potential role for cx43-hemichannels in staurosporin-induced apoptosis

To address the role of gap junction hemichannels in apoptosis, the cell death induced by staurosporine (ST) was evaluated in wild type HeLa cells (HeLa-WT) and transfectants expressing either full-length connexin43 (HeLa-Cx43) or a C-terminal truncation of Cx43 (HeLa-DeltaCT). Cell death was measured with fluorescence-activated cell sorting (FACS), both DNA and nuclear fragmentation methods and assays for PARP and caspase 3. The ST-mediated cell death was accelerated in HeLa-Cx43 cells compared to HeLa-WT and HeLa-DeltaCT. To determine why HeLa-Cx43 cells were more susceptible to ST, the phosphorylation state and the localization of Cx43 protein within cells were examined using specific Cx43 antibodies. The phosphorylated forms of Cx43 were sharply reduced in HeLa-Cx43 cells treated with ST. Moreover, in ST-treated HeLa-Cx43 cells, Cx43 was mainly observed at the cell surface. In contrast, the truncated form of Cx43 found in HeLa-DeltaCT cells, which lacks many of the normal phosphorylation sites, was observed in the cytosol with ST treatment. To examine the hemichannels in the plasma membranes of ST-treated HeLa-Cx43 cells, several dye uptake methods using carboxyfluorescein and propidium iodide were employed. While the number of fluorescent cells did not change in HeLa-WT and HeLa-DeltaCT cells with ST treatment, the number of fluorescent HeLa-Cx43 cells increased more than ten-fold. These results indicate that the increases in cell surface Cx43 seen with immunofluorescence and the elevated hemichannel activities detected with dye uptake could help explain the accelerated cell death observed in ST-treated HeLa-Cx43 cells.     

New Photosensitizers of Bacteriochlorin Series for Photodynamic Cancer Therapy

New derivatives of bacteriochlorophyll a bearing an extra glutarimide exocycle were synthesized, and their reactivity was studied. Acetyl group in 3-acetyl-2,7,12,18-tetramethyl-8-ethyl-13,15-dicarboxy-17-carboxyethyl-7,8,17,18-tetrahydroporphyrin (bacteriochlorin p) was chemically modified into -hydroxyethyl and vinyl groups. A simple method of preparation of vinylbacteriopurpurin esters under the catalysis by p-toluenesulfonic acid was proposed. The resulting compounds exhibit a high adsorption in the visible and near IR areas of electronic spectra, a reasonable stability, and amphiphilic properties and, therefore, may be regarded as promising photosensitizers for the photodynamic cancer therapy.