Endoplasmic reticulum-associated degradation (ERAD)is a protein quality control mechanism that eliminates unwanted proteins from the endoplasmic reticulum (ER) through a ubiquitin-dependent proteasomal degradation pathway. gp78 is a previously described ER membrane-anchored ubiquitin ligase (E3) involved in ubiquitination of ER proteins. AAA ATPase (ATPase associated with various cellular activities) p97/valosincontaining protein (VCP) subsequently dislodges the ubiquitinated proteins from the ER and chaperones them to the cytosol, where they undergo proteasomal degradation. We now report that gp78 physically interacts with p97/VCP and enhances p97/VCP-polyubiquitin association. The enhanced association correlates with decreases in ER stress-induced accumulation of olyubiquitinated proteins. This effect is abolished when the p97/VCP-interacting domain of gp78 is removed. Further, using ERAD substrate CD3, gp78 consistently enhances p97/VCP-CD3 binding and facilitates CD3 degradation. Moreover, inhibition of endogenous gp78 expression by RNA interference markedly increases the levels of total polyubiquitinated proteins, including CD3, and abrogates VCP-CD3 interactions. The gp78 mutant with deletion of its p97/VCP-interacting domain fails to increase CD3 degradation and leads to accumulation of polyubiquitinated CD3, suggesting a failure in delivering ubiquitinated CD3 for degradation. These data suggest that gp78-p97/VCP interaction may represent one way of coupling ubiquitination with retrotranslocation and degradation of ERAD substrates.

To investigate the curative effects of oral and nasal administration of chicken type II collagen (CII) on adjuvant arthritis (AA) in rats with meloxicam-induced intestinal lesions.

To investigate the effects and mechanisms of melatonin on immunological liver injury in mice.

To investigate the effects of Glucosides of Chaenomeles speciosa (GCS) on rat adjuvant arthritis (AA) and to clarify the role of synoviocytes in this process. METHODS: Complete Freund's adjuvant was used to induce AA in rats. Secondary paw swelling of AA rats was measured with MK-550 volume meter. The pain response and polyarthritis index were scored. Synoviocytes were separated by incubation of collagenase and trypsin, and morphological changes of synoviocytes were observed by transmission electron microscope. Interleukin-1 (IL-1) production was measured by thymocyte proliferation assay. Tumor necrosis factor (TNFα) and prostaglandin E2 (PGE2) production were determined by radioimmunoassay. RESULTS: There were significant secondary inflammatory reactions in AA rats. The morphology of synoviocytes from AA rats was changed, companying the elevation of the level of IL-1,TNFα, and PGE2 produced by synoviocytes from AA rats. GCS (60 and 120 mg/kg, ig, 8d) suppressed secondary inflammatory paw swelling, pain response, and polyarthritis index. It also improved ultrastructural changes of synoviocytes and inhibited IL-1,TNFα, and PGE2 production in AA rats. The inhibitory effect of GCS 120mg/kg was more evident than that of Actarit 60 mg/kg. CONCLUSION: GCS reduced the secondary inflammatory in AA rats, which is associated with prevention of ultrastructural changes of synoviocytes and inhibition of secretion of proimflammatory cytokines.

To investigate the role of melatonin in D-galactose-induced amnesic mice, the avoidance/escape and water maze tests were performed to evaluate their learning and memory function. Spectrophotometry was employed to determine the content of thiobarbituric acid-reactive substances (TBARS) and the activities of antioxidative enzymes in the brain. The present results demonstrate that D-galactose-induced amnesic mice had signir cantly decreased learning and memory function. The reduced activities of superoxide dismutase and glutathione peroxidase and increased levels of TBARS were found in brain tissue of the amnesic mice. Melatonin, administered (ig) at doses of 0.1, 1, or 10mg/kg to the D-galactose-treated mice for 3 months, was su

To investigate whether melatonin protects neurons from apoptosis, we used amyloid beta-peptide 25±35 (Ab25-35) to induce apoptosis in cultured hippocampal neurons, and monitored the apoptotic activity of the neurons with or without melatonin treatment. Present study shows that melatonin at concentrations of 1×10－6 and 1×10－5mol/L prevents neuronal morphological changes induced by apoptosis, as characterized by the shrunken and rounded morphology caused by condensed chromatin and fragmented DNA. Melatonin further exhibited the ability to inhibit apoptotic internucleosomal DNA degradation. Moreover, ow cytometric analysis of cell cycle demonstrated that melatonin abolished the Ab25-35-induced apoptotic peak. Our results suggest that melatonin may play an important role to protect neurons from Ab25±35-induced apoptosis.

This work investigated the ability of melatonin to prevent oxidative damage in brain tissue induced by injection of beta-amyloid peptide 25-35 (Ab25-35) in middle-aged rats. The Morris water maze was used to evaluate the cognitive function of the rats. Thiobarbituric acid-reactive substances and antioxidative enzymes (superoxide dismutase and glutathione peroxidase) activities were measured. It was found that injection of (Ab25-35) (20

To investigate the profile of endostatin on adjuvant arthritis (AA) and angiogenesis blockade in synovitis. METHODS: The model of rat AA was induced by injection of intradermal complete Freund's adjuvant (CFA). Hind paw volume of rat was measured by volume meter and the activities of interleukin-1 (IL-1) and IL-2 were measured by the assay of thymocytes proliferation. IL-1β and tumor necrosis factor-α (TNF-α) produced by synoviocytes was estimated with radioimmunoassay. The number of new blood vessels in knee joint synovium was counted under microscope by hematoxylin and eosin (HE) staining. RESULTS: The secondary inflammation of AA rats appeared on the 10th day after injection of CFA. The therapeutic administration of endostatin (0.1, 0.5, and 2.5mg·kg-1·d-1, sc, ×7d) was given from that time (d 10). It was found that endostatin significantly inhibited the secondary paw swelling and the number of new blood vessels in the synovium of AA rats. Endostatin significantly decreased the production of IL-1 derived from both peritoneal macrophages and synoviocytes and IL-2 from splenocytes, especially at the dose of 2.5mg/kg. This effect of endostatin also was seen on TNF-α produced by synoviocytes. CONCLUSION: The recombinant human endostatin had an inhibitory effect on rat AA, which was related to its anti-angiogenesis and inhibition of proinflammatory cytokines.

To study the effects and mechanisms of melatonin (MT) on immune responses in mice of different months. METHODS: Thymocyte proliferation and IL-2 activity were assayed by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) and activated mouse splenocyte proliferation methods, respectively; cAMP and methionine-enkephalin (met-Enk) level was determined by competitive protein binding assay and radioimmunoassay, respectively. RESULTS: The function of lymphocytes, obtained from BALB/c mice aged 6 and 11 months were decreased, which was restored by melatonin at the dose of 5 mg/kg or 30 mg/kg. In vitro, proliferation of lymphocytes in 11-month-old mice was decreased and cAMP level was increased. Melatonin (0.1nmol/L or 1mmol/L) had negative regulation to this. Forskolin (10 mmol/L) enhanced the cAMP level of lymphocytes in 2-and 11-month-old mice (P<0.01), which was antagonized partially by melatonin and this effect of melatonin was also abolished by pertussis toxin (1mg/L) completely. Melatonin (1mmol/L and 0.1nmol/L) increased the content of met-Enk of lymphocytes in 2-and 11-month-old mice, respectively (P<0.01), which was blocked by nifedipine (1 mmol/L). CONCLUSION: Melatonin exerted an effect on immune responses in mice of different months, which might be mediated by G protein-AC-cAMP signal transduction pathway and regulation of met-Enk level.