Briefly, tibiae were collected at 4, 12, or 26 wk of age; fixed in 4% paraformaldehyde/PBS; and embedded in methylmethacrylate. osteolytic hormones and cytokines, including parathyroid hormone and 1,25-dihydroxyvitamin D3 (1,25(OH)2-D3) (21, 22). OCs and OBs work together to remodel or reshape bone structures to optimize their resistance to mechanical forces as well as to repair the bone and enable bone growth. This occurs through bone resorption by OCs and is followed by bone formation by OBs, actions that are closely coupled and coordinated to maintain bone architecture such that OC stimulation may result in elevated OB numbers and gene (Gene ID 108097): a 3144-bp NarI-AgeI 5 homology arm, and a 6020-bp AgeI-(32), and were used between passages 5 and 20. RAW264.7 cells were obtained from the American Type Culture Collection (Manassas, VA, USA). Primary murine calvarial cell cultures were prepared from neonatal calvaria by sequential ABT digestion with 0.1% bacterial collagenase (Worthing Biochemical Co., Freefold, Australia) and 0.2% dispase (Godo Shusei, Tokyo, Japan), as described previously (21). Bone marrow cells were obtained by flushing the marrow cavities of the long bones with sterile saline. Bone marrow macrophages (BMMs) were prepared as described previously by incubating bone marrow cells in the presence of L-cell ABT conditioned medium (30%) for 3 d and removing the nonadherent cell fraction containing enriched macrophage and macrophage progenitors (33). Western blot analysis of protein expression Cultured cells were washed with ice-cold PBS, scraped off using a rubber policeman, and collected and lysed in lysis buffer A (50 mM Tris, pH 7.5; 1 mM EDTA; 1 mM EGTA; 50 mM NaF; 5 mM NaPO7; 10% glycerol (v/v); 1% TritonX-100 (v/v); 10 g/ml trypsin inhibitor; 2 g/ml aprotinin; 1 mM benzamidine; 1 mM phenylmethylsulfonyl fluoride; and 1 mM dithiothreitol). Samples were snap-frozen in liquid nitrogen and stored at ?80C. Lysate total protein concentrations were determined using a colorimetric BCA? Protein Assay Kit (Pierce, Rockford, IL, USA), and the absorbance at 562 nm was measured using a Polarstar Optima microplate reader (BMG Labtech, Australia). Samples were diluted to equal protein concentration using lysis buffer A. AMPK heterotrimers were immunoprecipitated from lysates as ABT described previously (23). Briefly, Protein A-Sepharose beads coupled to anti-AMPK1 and 2 antibodies were added to lysates for 2 h at 4C Mouse monoclonal to WNT5A on an orbital shaker, followed by successive washing with ice-cold 1 PBS, 2% Triton X-100/PBS, and again with PBS. Immunocomplexed beads were resuspended in either 50 mM Tris, pH 7.5, for AMPK activity assay (see below), or 3 sample loading buffer for Western blot analysis. Acetyl CoA carboxylase-1 (ACC1) was affinity-purified from cell lysates in a similar manner using streptavidin-sepaharose beads (Amersham). Purified complexes were heated (95C, 5 min), separated on 10% SDS-PAGE gels and transferred to PVDF membranes (Millipore, Bedford, MA, USA). Membranes were preincubated with blocking buffer (PBS, 0.1% v/v Tween20, and 5% w/v skim milk powder), rinsed in PBS, and incubated with primary antibodies at 1:1000 for 1 h at room temperature. In the case of detection of total ACC, streptavidin-horseradish peroxidase conjugate (GE Healthcare, UK) was used. ABT Rabbit polyclonal anti- and – AMPK subunit specific antibodies were produced in our laboratory and have been previously described (34, 35). Anti-1, -2, and -3 polyclonal antibodies were raised in rabbits against the following peptide sequences; rat 1 (319-331) CQALVLT GGEKKP, human 2 (555-569) CLTPAGAKQKETETE, and human 3 (59-75) AESTGLEATFPKTTPLC. Peptide antibodies were produced and purified by peptide affinity chromatography as previously outlined (35). Membranes were washed in PBS containing 0.1% Tween (PBS-T), incubated with horseradish peroxidase-conjugated protein G secondary antibody (1:2000; Bio-Rad, Hercules, CA, USA), and washed, and the immunoreactive proteins were detected with enhanced chemiluminescence (ECL) reagent. AMPK assays AMPK assays were performed as described previously.