HTLV-1 Tax-mediated TAK1 activation involves TAB2 adapter protein

Human T cell leukemia virus type 1 (HTLV-1) Tax is an oncoprotein that plays a crucial role in the proliferation and transformation of HTLV-1-infected T lymphocytes. It has recently been reported that Tax activates a MAPKKK family, TAK1. However, the molecular mechanism of Tax-mediated TAK1 activation is not well understood. In this report, we investigated the role of TAK1-binding protein 2 (TAB2) in Tax-mediated TAK1 activation. We found that TAB2 physically interacts with Tax and augments Tax-induced NF-κB activity. Tax and TAB2 cooperatively activate TAK1 when they are coexpressed. Furthermore, TAK1 activation by Tax requires TAB2 binding as well as ubiquitination of Tax. We also found that the overexpression of TRAF2, 5, or 6 strongly induces Tax ubiquitination. These results suggest that TAB2 may be critically involved in Tax-mediated activation of TAK1 and that NF-κB-activating TRAF family proteins are potential cellular E3 ubiquitin ligases toward Tax.     

Identification by an EPR technique of decreased mitochondrial reducing activity in puromycin aminonucleoside-induced nephrosis

The temporal changes in the electron paramagnetic resonance (EPR) signal intensities of a nitroxide radical, 4-hydroxy 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), in the kidney in rat puromycin aminonucleoside (PAN) nephrosis were investigated in vivo and in vitro. The rats of the PAN nephrosis group received intraperitoneal injections of PAN at 75 mg/kg body weight while those of control group received saline. The in vivo renal half-lives of TEMPOL were calculated from the decay curve of EPR signal intensities after the intravenous injection of the TEMPOL solution. The mitochondrial half-lives were obtained from the decay curve of the EPR signals after mixing the mitochondrial fraction of the kidney and TEMPOL solution. The in vivo half-lives of TEMPOL of the kidney from 7 to 14 d after PAN administration were significantly longer than those of the controls. The mitochondrial half-lives of TEMPOL on the 9th day after the PAN administration prolonged remarkably compared to the controls (378 +/- 69 vs. 676 +/- 183 s, p <.01). These findings indicate that the in vivo and mitochondrial reducing activity in PAN treated rats decreased markedly, because the half-life of TEMPOL in the kidney reflects the renal reducing activity.     

In Vivo Evaluation of Hippocampal Anti-Oxidant Ability of Zonisamide in Rats

We evaluated the anti-oxidant property of zonisamide (ZNS) in the rat brain under freely moving conditions by means of in vivo microdialysis of two exogenous nitroxide radicals, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL) and 3-methoxy carbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM). Time-dependent changes in the signal intensities of these exogenous nitroxide radicals obtained from the hippocampal perfusates were observed using an X-band ESR spectrometer at 20-min intervals. The ESR signal intensities of nitroxide radicals decreased exponentially in all animals, which indicates that their half-life could be used as a parameter to estimate the decay rate of nitroxide radicals. Nitroxide radicals lose their paramagnetism when exposed to reductants in a biological system. Thus, half-life reflects the in vivo reducing ability. Although the half-life of carbamoyl-PROXYL, which could not pass the blood-brain barrier (BBB), was not changed when compared with the controls, pre-treatment with ZNS significantly shortened the half-life of PCAM, which could pass through the BBB. These findings suggest that the ZNS-induced increase in reducing ability did not occur within the extracellular space, but rather mainly at the neural cell membrane. This study is the first in vivo evaluation of the reducing ability of ZNS in freely moving animals.     

A study on conformationally restricted sangivamycins and their inhibitory abilities of protein kinases.

Conformational restrictions of sangivamycin, a rather selective inhibitor of PKC, could be achieved by the use of the steric effect and the gauche effect of the substituents on the ribofuranose moiety. The conformational deviations obtained by these methods were found to nicely correlate with the inhibitory ability of PKC.     

Spontaneous skin damage and delayed wound healing in SOD1-deficient mice

Superoxide dismutase 1 (SOD1) is an important antioxidative enzyme that protects skin from oxidative stress. SOD1 ^?/? mice with a genetic background of b129Sv mice showed facial skin damage after 15 weeks of age. Eyelid swelling occurred as the initial symptom and caused impairment by triggering self-scratching. The period required for wound healing in the back was markedly delayed in 20-week SOD1 ^?/? mice. Oxidative stress markers, 4-hydroxynonenal and thiobarbituric acid-reactive substances, were unexpectedly lower in SOD1 ^?/? mice at day 1 after wounding. The decay rate of electron paramagnetic resonance signal intensity of intravenously injected nitroxide radical indicated that the half-life of the signal intensity was significantly prolonged in the wounded skin of SOD1 ^+/+ mice. However, while the half-life of the signal intensity in control skin was a little longer in SOD1 ^?/? mice, it did not change in wounded skin. Taken together, these data suggest that the skin of SOD1 ^?/? mice is in redox imbalance and prone to damage by wounding.     

Preparation of immobilized invertase

Immobilized invertase was prepared by ionically binding the enzyme to diethylaminoacetyl cellulose (DEAA-cellulose). DEAA-cellulose-invertase complex was quite stable to electrolyte in the range of pH 5–7. Bound invertase was less active than the native enzyme, and approximately 55–70% of the enzyme activity was lost on binding. The complex was stable for 9 days' continuous inversion in a column system at 30°C, but was rather unstable at 40°C. Heat stability and the effect of temperature on the reaction rate of the complex were almost identical with those of the native enzyme.