Non-specific binding. The blot was subsequently incubated with an anti-HIF-1a rabbit polyclonal antibody (1:200, Abcam), an anti-Sost rabbit polyclonal antibody (1:60, Abcam), or an anti-HSP90 rabbit polyclonal antibody (1:200, Abcam) followed by a secondary antibody (peroxidase-conjugated antirabbit IgG 1:5000, Sigma). After each antibody incubation, blots were extensively washed in TBS containing 0.1 Tween-20. For detection, the ECL kit (Amersham Life Sciences) was used according to the directions of the manufacturer.siRNA Interference RNA Isolation and Real-time RT-PCRTotal RNA was isolated from MC3T3 osteoblasts with TRIzol reagent (Invitrogen) followed by RNeasy mini kit (Qiagen) as previously described [27]. TaqMan One-Step RT-PCR Master Mix reagent (Applied Biosystems) was used for quantitative RTPCR. Reaction volume is 50 ul per well on 96-well plates. Analysis was performed with ABI PRISM 7500 sequence detection system (Applied Biosystems). Primers were ordered from Applied Biosystems. Transcript levels were normalized to heat shock protein 90 (HSP90) levels. All reactions were done in duplicate and all experiments were repeated at least three times. The relative mRNA expression levels were calculated according to the comparative CT (DDCT) method as described by the manufacturer (User Bulletin #2, Applied Biosystems). Target quantity is normalized to endogenous control and relative to a calibrator, and is calculated using formula: Target amount = 22DDCT. MC3T3 cells were transfected by siRNA against mouse HIF-1a with Lipofectamine 2000 as previously described [29]. siRNA oligos were purchased from Thermo Scientific Dharmacon, and siGENOME Lamin A/C Control siRNA was used as a nonspecific control. Cells were cultured in 6-well plates. One day before transfection, cells were plated in 1 ml of growth medium without antibiotics. Cells were 30?0 confluent at the time of transfection. For each sample, siRNA:Lipofectamine. 2000 transfection complex was prepared as follows: (1) Dilute 2 ml of 50 mM siRNA in 50 ml of Opti-MEM I Reduced Serum Medium without serum; (2) Mix Lipofectamine. 2000 gently, then dilute 3 ml in 50 ml of Opti-MEM I Medium; (3) Combine the diluted siRNA with the diluted Lipofectamine. 2000; (4) Add 100 ml of siRNA:Lipofectamine. 2000 complex to each 23148522 well. After 4 hours incubation, the growth medium was replaced. Cells were cultured at 37uC in a CO2 incubator for 24 hours before harvest.Protein Purification and Western BlotProtein was isolated by acetone precipitation from the cell lysates as previously described [28]. The protein pellet was dissolved in 1 SDS buffer, warmed for 15 min at 55uC, and centrifuged for 5 min at 14000 rpm. Protein concentrations in theTransient Transfection AssayHEK293 cells were plated in 12-well plates, cultured to 60 ?80 confluence and transfected with FuGENE 6 (Roche) as previously described [30]. Cells were cotransfected with 300 ng of Sost promoter reporter, HIF-1a- expression plasmid as indicated and 25 ng of pSV2-beta-gal. After transfection, cells wereHIF-1a Activates Sost Gene ExpressionFigure 4. Effect of HIF-1a on Sost promoter activity. (A) HIF-1a activates the Sost promoter in a Title Loaded From File dose-dependent manner. HEK293 cells were transfected with a 1 kb Sost promoter-luciferase reporter gene without or with increasing amounts of an HIF-1a-expression plasmid as indicated. Luciferase activity was normalized by b-galactosidase activity. St well-characterized heme importer and exporter respectively. As shown in Figure Values are presented as the mean 6S.D. (B) Jab1.Non-specific binding. The blot was subsequently incubated with an anti-HIF-1a rabbit polyclonal antibody (1:200, Abcam), an anti-Sost rabbit polyclonal antibody (1:60, Abcam), or an anti-HSP90 rabbit polyclonal antibody (1:200, Abcam) followed by a secondary antibody (peroxidase-conjugated antirabbit IgG 1:5000, Sigma). After each antibody incubation, blots were extensively washed in TBS containing 0.1 Tween-20. For detection, the ECL kit (Amersham Life Sciences) was used according to the directions of the manufacturer.siRNA Interference RNA Isolation and Real-time RT-PCRTotal RNA was isolated from MC3T3 osteoblasts with TRIzol reagent (Invitrogen) followed by RNeasy mini kit (Qiagen) as previously described [27]. TaqMan One-Step RT-PCR Master Mix reagent (Applied Biosystems) was used for quantitative RTPCR. Reaction volume is 50 ul per well on 96-well plates. Analysis was performed with ABI PRISM 7500 sequence detection system (Applied Biosystems). Primers were ordered from Applied Biosystems. Transcript levels were normalized to heat shock protein 90 (HSP90) levels. All reactions were done in duplicate and all experiments were repeated at least three times. The relative mRNA expression levels were calculated according to the comparative CT (DDCT) method as described by the manufacturer (User Bulletin #2, Applied Biosystems). Target quantity is normalized to endogenous control and relative to a calibrator, and is calculated using formula: Target amount = 22DDCT. MC3T3 cells were transfected by siRNA against mouse HIF-1a with Lipofectamine 2000 as previously described [29]. siRNA oligos were purchased from Thermo Scientific Dharmacon, and siGENOME Lamin A/C Control siRNA was used as a nonspecific control. Cells were cultured in 6-well plates. One day before transfection, cells were plated in 1 ml of growth medium without antibiotics. Cells were 30?0 confluent at the time of transfection. For each sample, siRNA:Lipofectamine. 2000 transfection complex was prepared as follows: (1) Dilute 2 ml of 50 mM siRNA in 50 ml of Opti-MEM I Reduced Serum Medium without serum; (2) Mix Lipofectamine. 2000 gently, then dilute 3 ml in 50 ml of Opti-MEM I Medium; (3) Combine the diluted siRNA with the diluted Lipofectamine. 2000; (4) Add 100 ml of siRNA:Lipofectamine. 2000 complex to each 23148522 well. After 4 hours incubation, the growth medium was replaced. Cells were cultured at 37uC in a CO2 incubator for 24 hours before harvest.Protein Purification and Western BlotProtein was isolated by acetone precipitation from the cell lysates as previously described [28]. The protein pellet was dissolved in 1 SDS buffer, warmed for 15 min at 55uC, and centrifuged for 5 min at 14000 rpm. Protein concentrations in theTransient Transfection AssayHEK293 cells were plated in 12-well plates, cultured to 60 ?80 confluence and transfected with FuGENE 6 (Roche) as previously described [30]. Cells were cotransfected with 300 ng of Sost promoter reporter, HIF-1a- expression plasmid as indicated and 25 ng of pSV2-beta-gal. After transfection, cells wereHIF-1a Activates Sost Gene ExpressionFigure 4. Effect of HIF-1a on Sost promoter activity. (A) HIF-1a activates the Sost promoter in a dose-dependent manner. HEK293 cells were transfected with a 1 kb Sost promoter-luciferase reporter gene without or with increasing amounts of an HIF-1a-expression plasmid as indicated. Luciferase activity was normalized by b-galactosidase activity. Values are presented as the mean 6S.D. (B) Jab1.
