AbstractIntroductionMicrogravity is thought to decrease osteoblastic activity and induce osteoporosis during spaceflight, but the mechanisms, particularly the attendant changes in gene expression, are not well understood. It is suspected that the cytoskeletal system is involved in the manifold changes of cell shape, function, and signaling under microgravity conditions.MethodsWe constructed cell lines stably transfected with pJI36EGFP and pJI23EGFP, which contained a 3.6 and a 2.3kb fragment, respectively, of the α1(I) collagen gene (COL1A1) promoter fused with the enhanced green fluorescence protein (EGFP) reporter gene. We then developed a semi-quantitative analysis of EGFP fluorescence intensity to evaluate the effects of clinorotation and/or cytochalasin B on the activity of the COL1A1 promoter. Simultaneously, we assessed the collagen type I protein content versus total protein content in clinorotated or control osteoblasts, using immunocytochemistry and the Bradford method, respectively.ResultsThe fluorescence intensity analysis revealed that the expression of COL1A1-EGFP increased in GFP-ROS cells clinorotated for 24 or 48h, as compared with stationary control cultures. We observed a similar trend in collagen type I content, as assessed by immunocytochemistry. We found that the osteoblast microfilaments tended to disassemble and show a reduction in stress fibers under space flight and clinorotation. Treatment with cytochalasin B in normal gravity resulted in a dose-dependent increase of EGFP fluorescence intensity, indicating that disruption of the actin system was associated with increased activity of the COL1A1 promoter.ConclusionOur study demonstrates that disrupting the actin cytoskeleton by treatment with cytochalasin B and real or simulated microgravity conditions led to altered COL1A1 promoter activity. Together, these results suggest that actin may participate in the regulation of the COL1A1 promoter activity under microgravity conditions.


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    Titel :

    Actin microfilaments participate in the regulation of the COL1A1 promoter activity in ROS17/2.8 cells under simulated microgravity


    Beteiligte:
    Dai, Zhongquan (Autor:in) / Li, Yinghui (Autor:in) / Ding, Bai (Autor:in) / Zhang, Xiaoyou (Autor:in) / Tan, Yingjun (Autor:in) / Wan, Yumin (Autor:in)

    Erschienen in:

    Advances in Space Research ; 38 , 6 ; 1159-1167


    Erscheinungsdatum :

    2006-02-05


    Format / Umfang :

    9 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch





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