ECTS2013 Poster Presentations Cell biology: osteoclasts and bone resorption (24 abstracts)
Inhibition of lipopolysacharide induced osteoclast formation and bone resorption in vitro and in vivo in mice by cystatin C
Strålberg Fredrik 1 , Catharina Lindholm 2 , Erik Lindström 5 , Franciszek Kasprzykowski 3 , Paul Saftig 6 , Magnus Abrahamson 4 , Anders Grubb 4 & Ulf H Lerner 1,
1Molecular Periodontology, Umeå, Sweden; 2Center for Bone and Arthritis Research (CBAR), Gothenburg, Sweden; 3Institute of Chemistry, Gdansk, Poland; 4Clinical Chemistry And Pharmacology, Lund, Sweden; 5Pharmacology and Molecular Sciences, Medivir, Stockholm, Sweden; 6Institute of Biochemistry (CAU), Kiel, Germany.
RANKL induced osteoclastogenesis is mediated by several transcription factors such as NF-κB, AP-1 and Nfatc1. We have found that also cysteine proteinases are involved in the signaling pathway downstream RANK. Thus, cystatin C, Z-RLVG-CHN2 (the sequence of which is based upon one of the enzyme inhibitory domains in cystatin C) and the fungal molecule E-64 – inhibit RANKL induced mouse and human osteoclast formation in vitro (Strålberg et al. in revision). Here, we demonstrate that osteoclastogenesis stimulated by lipopolysacharide (LPS) E.coli (10 μg/ml) in RANKL-primed (4 ng/ml RANKL for 24 h) mouse bone marrow macrophages (BMM) is inhibited by cystatin C, Z-RLVG-CHN2 and E-64. The effect was associated with decreased LPS-induced mRNA expression of Acp5, Ctsk, Calcr, Cfos, and Nfatc1, and protein expression of NFATc1 and c-Fos. Using fluorescent tagged cystatin C, we found that cystatin C was taken up by BMM, but only in LPS stimulated cells. Inhibition of osteoclastogenesis by cystatin C was observed also using LPS stimulated BMM on bone slices. Cystatin C inhibited LPS induced upregulation of JunB, Fra-2, p52, RelB, and IκBα mRNA. All three cysteine proteinase inhibitors using BMM from cathepsin K deficient mice also inhibited osteoclast formation. Similarly, the cathepsin K inhibitor L-006235 did not inhibit osteoclast formation. The data suggest that cystatin C inhibits osteoclast formation by inhibiting LPS-induced differentiation of osteoclast progenitors and that the effect is due to inhibition of signaling pathways downstream TLR-4 known to be important in RANKL-induced osteoclastogenesis. Most importantly, LPS-stimulated osteoclast formation in skull bones of adult mouse was inhibited by E-64, as assessed by counting the number of cathepsin K+ osteoclasts. These data indicate that i) cysteine proteinases are important in LPS- and RANKL-induced osteoclastogenesis both in vitro and in vivo, and ii) inhibition of osteoclast formation is not explained by inhibition of cathepsin K activity.
Article tools
My recent searches
My recently viewed abstracts
Authors
Bone Abstracts
ISSN 2052-1219 (online)
© Bioscientifica 2024 |
Privacy policy |
Cookie settings
BiosciAbstracts
Bioscientifica Abstracts is the gateway to a series of products that provide a permanent, citable record of abstracts for biomedical and life science conferences.
Find out more