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Evidence is accumulating that osteal macrophages, in addition to bone-resorbing osteoclasts and bone-forming osteoblasts, participate vitally in bone remodeling process. Oncostatin M (OSM), an inflammatory cytokine belonging to interleukin-6 superfamily, is recognized as an essential factor secreted by osteal macrophages to orchestrate bone remodeling. Osteoprotegerin (OPG) produced by osteoblasts regulates osteoclastogenesis. We have reported that bone morphogenetic protein-4 (BMP-4) stimulates OPG synthesis in MC3T3-E1 osteoblast-like cells, and that SMAD1/5/8(9), p38 mitogen-activated protein kinase (MAPK), and p70 S6 kinase are involved in the OPG synthesis. The present study aims to investigate the effect of OSM on the synthesis of OPG stimulated by BMP-4 in osteoblasts. OSM suppressed the release and the mRNA expression of OPG upregulated by BMP-4 in MC3T3-E1 cells. Neither the BMP-4-induced phosphorylation of SMAD1/5/9 nor that of p38 MAPK was affected by OSM. On the other hand, the phosphorylation of p70 S6 kinase stimulated by BMP-4 was considerably suppressed by OSM. These results strongly suggest that OSM suppresses the BMP-4-stimulated OPG synthesis via inhibition of the p70 S6 kinase-mediated pathway in osteoblast-like cells., (© 2024 The Author(s). Cell Biochemistry and Function published by John Wiley & Sons Ltd.)

Heat shock protein 90 (HSP90) is expressed ubiquitously in a variety of cell types including osteoblasts. HSP90 acts as a key driver of proteostasis under pathophysiological conditions. Here, we investigated the involvement of HSP90 in extracellular ATP-stimulated interleukin (IL)-6 synthesis and HSP90 downstream signalling in osteoblast-like MC3T3-E1 cells. In osteoblasts, extracellular ATP stimulates the synthesis of IL-6, a bone-remodelling agent. Geldanamycin, 17-allylamino-17-demethoxy-geldanamycin (17-AAG) and onalespib, three different HSP90 inhibitors, amplified the ATP-stimulated IL-6 release. Geldanamycin increased IL-6 mRNA expression elicited by ATP. ATP enhanced the triiodothyronine-induced osteocalcin release, but HSP90 inhibitors suppressed the release. Extracellular ATP induced the phosphorylation of p44/p42 mitogen-activated protein kinase (MAPK), p38 MAPK, c-Jun N-terminal kinase (JNK), p70 S6 kinase, Akt, and myosin phosphatase-targeting subunit (MYPT), a Rho-kinase substrate. SB203580, an inhibitor of p38 MAPK, suppressed ATP-stimulated IL-6 release. Inhibitors of MEK1/2 (PD98059), JNK (SP600125), upstream kinase of p70 S6 kinase (rapamycin) and Akt (deguelin), all increased IL-6 release. Y27632, a Rho-kinase inhibitor, failed to affect the IL-6 release stimulated by ATP. Geldanamycin and 17-AAG both amplified ATP-induced p38 MAPK phosphorylation, although geldanamycin inhibited the phosphorylation of Akt induced by ATP. In addition, SB203580 significantly reduced the amplification by geldanamycin of the IL-6 release. Taken together, our results strongly suggest that HSP90 inhibitors up-regulate extracellular ATP-stimulated IL-6 synthesis via amplification of p38 MAPK activation in osteoblasts. SIGNIFICANCE OF THE STUDY: Heat shock protein 90 (HSP90) acts as a key driver of proteostasis under pathophysiological conditions in a variety of cell types. We have previously shown that HSP90 is expressed at high levels in osteoblast-like MC3T3-E1 cells, even in their quiescent state, consistent with HSP90 performing an important physiological function in osteoblasts. In the present study, we investigated whether HSP90 is implicated in extracellular ATP-induced interleukin (IL)-6 synthesis in osteoblast-like MC3T3-E1 cells. Our results strongly suggest that HSP90 inhibitors up-regulate extracellular ATP-stimulated IL-6 synthesis via amplification of p38 mitogen-activated protein kinase activation in osteoblasts., (© 2020 John Wiley & Sons Ltd.)

Apremilast is a novel oral phosphodiesterase 4 inhibitor effective for psoriasis. It regulates the production of pro-inflammatory mediators. Apremilast was approved in December 2016 in Japan; however, its efficacy and safety in a real-world setting among Japanese patients have not been reported. We report on 44 patients treated with apremilast between March and October 2017. The median treatment duration was 25 weeks (range, 2-33). Thirty-five patients (79.5%) continued the drug for at least 23 weeks, and five (11.4%) achieved a Psoriasis Area and Severity Index 100 response within 12 weeks. Nine patients discontinued the drug within 24 weeks mainly due to insufficient efficacy (n = 3) and adverse events (n = 4). Seven patients continued their previous systemic therapies such as cyclosporin (n = 1), methotrexate (n = 1), etretinate + methotrexate (n = 1) and biologics (n = 4) combined with apremilast. Of these patients, 55.9% had at least one adverse event although no severe adverse events. The most common adverse event was diarrhea (31.8%), followed by nausea (25.0%), headache (13.6%), abdominal discomfort (6.8%) and vomiting (6.8%). The proportion of diarrhea in our patients was higher than those of previous clinical trials. Among 10 patients with psoriatic arthritis, apremilast did not improve joint pain in nine (90%). To investigate the relationship between treatment efficacy and plaque size, we defined a small plaque as an individual rash diameter of 1 inch or less. The efficacy of apremilast was greater in patients with small plaques than in patients with large plaques., (© 2018 Japanese Dermatological Association.)

The catalytic domain of death-associated protein kinase (DAPK) has been overexpressed, purified and crystallized using the sitting-drop vapour-diffusion method with PEG 8000 and magnesium acetate as precipitants. Complexes with the inhibitor staurosporine and its analogue BDB402 were also crystallized in the presence of PEG 400 and PEG 8000, respectively. Diffraction data were collected to 2.4 A for the native catalytic domain, to 2.9 A for the staurosporine complex and to 2.7 A for the BDB402 complex. All three crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 77.992, b = 109.909, c = 50.063 A for the catalytic domain, a = 78.911, b = 113.162, c = 50.658 A for the staurosporine complex and a = 77.337, b = 108.869, c = 50.186 A for the BDB402 complex. In both complexes the inhibitor molecule was clearly assigned in the difference Fourier map calculated on the basis of the phases obtained from the structure of the catalytic domain.