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Adiponectin and AMP kinase activator stimulate proliferation, differentiation, and mineralization of osteoblastic MC3T3-E1 cells.

Kanazawa I, Yamaguchi T, Yano S, Yamauchi M, Yamamoto M, Sugimoto T - BMC Cell Biol. (2007)

Bottom Line: AdipoR1 small interfering RNA (siRNA) transfection potently knocked down the receptor mRNA, and the effect of this knockdown persisted for as long as 10 days after the transfection.The transfected cells showed decreased expressions of type I collagen and osteocalcin mRNA, as determined by real-time PCR, and reduced ALP activity and mineralization, as determined by von Kossa and Alizarin red stainings.Taken together, this study suggests that adiponectin stimulates the proliferation, differentiation, and mineralization of osteoblasts via the AdipoR1 and AMP kinase signaling pathways in autocrine and/or paracrine fashions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Internal Medicine 1, Shimane University School of Medicine, Japan. ippei.k@med.shimane-u.ac.jp

ABSTRACT

Background: Adiponectin is a key mediator of the metabolic syndrome that is caused by visceral fat accumulation. Adiponectin and its receptors are known to be expressed in osteoblasts, but their actions with regard to bone metabolism are still unclear. In this study, we investigated the effects of adiponectin on the proliferation, differentiation, and mineralization of osteoblastic MC3T3-E1 cells.

Results: Adiponectin receptor type 1 (AdipoR1) mRNA was detected in the cells by RT-PCR. The adenosine monophosphate-activated protein kinase (AMP kinase) was phosphorylated by both adiponectin and a pharmacological AMP kinase activator, 5-amino-imidazole-4-carboxamide-riboside (AICAR), in the cells. AdipoR1 small interfering RNA (siRNA) transfection potently knocked down the receptor mRNA, and the effect of this knockdown persisted for as long as 10 days after the transfection. The transfected cells showed decreased expressions of type I collagen and osteocalcin mRNA, as determined by real-time PCR, and reduced ALP activity and mineralization, as determined by von Kossa and Alizarin red stainings. In contrast, AMP kinase activation by AICAR (0.01-0.5 mM) in wild-type MC3T3-E1 cells augmented their proliferation, differentiation, and mineralization. BrdU assay showed that the addition of adiponectin (0.01-1.0 mug/ml) also promoted their proliferation. Osterix, but not Runx-2, appeared to be involved in these processes because AdipoR1 siRNA transfection and AICAR treatments suppressed and enhanced osterix mRNA expression, respectively.

Conclusion: Taken together, this study suggests that adiponectin stimulates the proliferation, differentiation, and mineralization of osteoblasts via the AdipoR1 and AMP kinase signaling pathways in autocrine and/or paracrine fashions.

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Effects of recombinant adiponectin and AICAR treatments on BrdU incorporation by MC3T3-E1 cells. Cells were exposed to 0.01–1.0 μg/ml adiponectin or 0.01–0.5 mM AICAR for 24 h. Cell proliferation was determined by measuring the amount of incorporated BrdU. Proliferation was significantly promoted by both low dose adiponectin (A) and AICAR (B) treatments (p < 0.01). The results were the representative of three different experiments.
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Figure 9: Effects of recombinant adiponectin and AICAR treatments on BrdU incorporation by MC3T3-E1 cells. Cells were exposed to 0.01–1.0 μg/ml adiponectin or 0.01–0.5 mM AICAR for 24 h. Cell proliferation was determined by measuring the amount of incorporated BrdU. Proliferation was significantly promoted by both low dose adiponectin (A) and AICAR (B) treatments (p < 0.01). The results were the representative of three different experiments.

Mentions: We found that after 24-h incubation with adiponectin or AICAR, BrdU incorporation was significantly enhanced in MC3T3-E1 cells (p < 0.01) (Figs. 9A and 9B, respectively). These results showed that adiponectin and the AMP kinase activator stimulated the proliferation of the cells.


Adiponectin and AMP kinase activator stimulate proliferation, differentiation, and mineralization of osteoblastic MC3T3-E1 cells.

Kanazawa I, Yamaguchi T, Yano S, Yamauchi M, Yamamoto M, Sugimoto T - BMC Cell Biol. (2007)

Effects of recombinant adiponectin and AICAR treatments on BrdU incorporation by MC3T3-E1 cells. Cells were exposed to 0.01–1.0 μg/ml adiponectin or 0.01–0.5 mM AICAR for 24 h. Cell proliferation was determined by measuring the amount of incorporated BrdU. Proliferation was significantly promoted by both low dose adiponectin (A) and AICAR (B) treatments (p < 0.01). The results were the representative of three different experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2214728&req=5

Figure 9: Effects of recombinant adiponectin and AICAR treatments on BrdU incorporation by MC3T3-E1 cells. Cells were exposed to 0.01–1.0 μg/ml adiponectin or 0.01–0.5 mM AICAR for 24 h. Cell proliferation was determined by measuring the amount of incorporated BrdU. Proliferation was significantly promoted by both low dose adiponectin (A) and AICAR (B) treatments (p < 0.01). The results were the representative of three different experiments.
Mentions: We found that after 24-h incubation with adiponectin or AICAR, BrdU incorporation was significantly enhanced in MC3T3-E1 cells (p < 0.01) (Figs. 9A and 9B, respectively). These results showed that adiponectin and the AMP kinase activator stimulated the proliferation of the cells.

Bottom Line: AdipoR1 small interfering RNA (siRNA) transfection potently knocked down the receptor mRNA, and the effect of this knockdown persisted for as long as 10 days after the transfection.The transfected cells showed decreased expressions of type I collagen and osteocalcin mRNA, as determined by real-time PCR, and reduced ALP activity and mineralization, as determined by von Kossa and Alizarin red stainings.Taken together, this study suggests that adiponectin stimulates the proliferation, differentiation, and mineralization of osteoblasts via the AdipoR1 and AMP kinase signaling pathways in autocrine and/or paracrine fashions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Internal Medicine 1, Shimane University School of Medicine, Japan. ippei.k@med.shimane-u.ac.jp

ABSTRACT

Background: Adiponectin is a key mediator of the metabolic syndrome that is caused by visceral fat accumulation. Adiponectin and its receptors are known to be expressed in osteoblasts, but their actions with regard to bone metabolism are still unclear. In this study, we investigated the effects of adiponectin on the proliferation, differentiation, and mineralization of osteoblastic MC3T3-E1 cells.

Results: Adiponectin receptor type 1 (AdipoR1) mRNA was detected in the cells by RT-PCR. The adenosine monophosphate-activated protein kinase (AMP kinase) was phosphorylated by both adiponectin and a pharmacological AMP kinase activator, 5-amino-imidazole-4-carboxamide-riboside (AICAR), in the cells. AdipoR1 small interfering RNA (siRNA) transfection potently knocked down the receptor mRNA, and the effect of this knockdown persisted for as long as 10 days after the transfection. The transfected cells showed decreased expressions of type I collagen and osteocalcin mRNA, as determined by real-time PCR, and reduced ALP activity and mineralization, as determined by von Kossa and Alizarin red stainings. In contrast, AMP kinase activation by AICAR (0.01-0.5 mM) in wild-type MC3T3-E1 cells augmented their proliferation, differentiation, and mineralization. BrdU assay showed that the addition of adiponectin (0.01-1.0 mug/ml) also promoted their proliferation. Osterix, but not Runx-2, appeared to be involved in these processes because AdipoR1 siRNA transfection and AICAR treatments suppressed and enhanced osterix mRNA expression, respectively.

Conclusion: Taken together, this study suggests that adiponectin stimulates the proliferation, differentiation, and mineralization of osteoblasts via the AdipoR1 and AMP kinase signaling pathways in autocrine and/or paracrine fashions.

Show MeSH
Related in: MedlinePlus