p38 MAPK and NF-kappaB on IL-6 release in human gingival fibroblasts.

The induction of interleukin-6 (IL-6) using a proinflammatory cytokine (IL-1beta) was studied in human gingival fibroblasts (HGFs) in relation to p38 MAPK and NF-kappaB transcription factor. When added to HGFs, IL-1beta had a stimulatory effect on the production of IL-6, and this effect was significantly reduced by SB203580, a specific p38 MAPK inhibitor. In addition, the stimulation of IL-6 release also was reduced by the addition of pyrrolidine dithiocarbamate or NF-kappaB SN50, which has been reported as potent NF-kappaB inhibitor. Both the NF-kappaB inhibitors in the presence of SB203580 had more inhibitory effect on IL-6 release. IL-13 stimulated NF-kappaB binding affinity as well as p38 MAP kinase activation, leading to the release of IL-6. However, a specific inhibitor of p38 MAPK, SB203580, had no effect on the NF-kappaB activation, and both the NF-kappaB inhibitors failed to reduce the p38 MAPK activation in the IL-1beta-stimulated HGFs. These results strongly suggest that both p38 MAPK and NF-kappaB are required in IL-1beta-induced IL-6 synthesis and that these two IL-1beta-activated pathways can be primarily dissociated.

ERK MAP Kinase is required in 1,25(OH)2D3-induced differentiation in human osteoblasts.

Expression of alkaline phosphatase(ALP)activity represents a key event during the differentiation processes of osteoblasts, and the level of ALP activity has been routinely used as a relative measure of differentiation stages of osteoblasts. In human osteoblasts, we showed that vitamin D3 analogue, 1,25(OH)2D3, had a stimulatory effect on ALP activity after 3 days, compared with control. The treatment of PD098059, an ERK MAP Kinase inhibitor, had a reducing effect on ALP activity, a differentiation marker in 1,25(OH)2D3-treated primary human osteoblasts. However, SB203580, a potent p38 MAP Kinase inhibitor, had no effect on the differentiation in this system. This indicates that ERK, not p38, is directly related to 1,25(OH)2D3-stimulated ALP activity in primary human osteoblasts. These results also show that the vitamin D3 analogue stimulates ERK1 activation in primary human osteoblasts. This finding provides one of signaling pathways for differentiation in primary human osteoblasts.

Molecular mechanism of staurosporine-induced apoptosis in osteoblasts.

Staurosporine, a microbial alkaloid, is a strong inhibitor of protein kinases. We induced apoptosis in murine osteoblast MC3T3E-1 cells by exposure to the staurosporine. Staurosporine transiently increased the phosphotransferase activity of c-Jun N-terminal kinase-1 (JNK1), which in turn may activate the transcriptional activity of activating protein-1 (AP-1). We then prepared extracts from staurosporine-treated MC3T3E-1 cells and monitored the cleavage of acetyl-YVAD-AMC and acetyl-DEVD-AMC, fluorogenic substrates of caspase-1-like and caspase-3-like proteases, respectively. Staurosporine caused a significant increase in the proteolytic activity of caspase-3-like proteases, but not in the activity of caspase-1-like proteases. Furthermore, staurosporine increased the transcriptional activity of nuclear factor- kappa B (NF- kappa B). These data suggest that staurosporine-induced apoptosis in osteoblasts may occur via activation of JNK1, caspase-3-like proteases, and transcriptional factors including AP-1 and NF- kappa B.

Fiber Bragg grating temperature sensor with controllable sensitivity.

We demonstrate a fiber Bragg grating (FBG) sensor with controllable sensitivity by connecting two metal strips that have different temperature-expansion coefficients. By changing the lengths of the metal strips we successfully controlled and improved the temperature sensitivity to 3.3 times of that of bare FBG.