Gap junctional communication modulates gene expression in osteoblastic cells
Gap junctional communication modulates gene expression in osteoblastic cells
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DOI：
10.1091/mbc.9.8.2249
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发表时间：
1998-08-01
影响因子：
3.3
通讯作者：
Civitelli, R
中科院分区：
文献类型：
--
作者：
Lecanda, F;Towler, DA;Civitelli, R
骨形成细胞通过间隙连接组织成多细胞网络。在这些细胞中，缝隙连接由连接蛋白43（Cx43）和连接蛋白45（Cx45）形成。Cx43间隙连接形成的孔比Cx45孔对带负电荷的染料如荧光黄和钙黄绿素更可渗透。我们研究了通过操纵Cx43和Cx45的相对表达来改变缝隙连接通讯是否会影响成骨细胞的表型。在主要表达Cx43的细胞（ROS 17/2.8和MC 3 T3-E1）中转染Cx45降低了染料转移和骨钙素（OC）和骨唾液蛋白（BSP）的表达，这些基因对骨基质形成和钙化至关重要。相反，将Cx43转染到主要表达Cx45的细胞（UMR 106-01）中增加了细胞偶联以及OC和BSP的表达。启动子荧光素酶构建体和连接蛋白表达载体的瞬时共转染表明，在ROS 17/2.8和MC 3 T3-E1细胞中，OC和BSP基因转录被Cx45共转染下调，与染料偶联的减少相关。相反，在UMR 106-01细胞中共转染Cx43上调OC和BSP基因转录。其他特异性较低的成骨细胞启动子，如骨桥蛋白和骨连接蛋白的活性，对缝隙连接通讯的变化不太敏感。因此，通过操纵成骨细胞中Cx43和Cx45的表达来改变间隙连接通透性，可能是通过调节可以从细胞扩散到细胞的信号来改变成骨细胞特异性启动子的转录活性。细胞间的通讯网络是分化成骨细胞表型的完整表达所必需的。
Bone-forming cells are organized in a multicellular network interconnected by gap junctions. Ln these cells, gap junctions are formed by connexin43 (Cx43) and connexin45 (Cx45). Cx43 gap junctions form pores that are more permeable to negatively charged dyes such as Lucifer yellow and calcein than are Cx45 pores. We studied whether altering gap junctional communication by manipulating the relative expression of Cx43 and Cx45 affects the osteoblast phenotype. Transfection of Cx45 in cells that express primarily Cx43 (ROS 17/2.8 and MC3T3-E1) decreased both dye transfer and expression of osteocalcin (OC) and bone sialoprotein (BSP), genes pivotal to bone matrix formation and calcification. Conversely, transfection of Cx43 into cells that express predominantly Cx45 (UMR 106-01) increased both cell coupling and expression of OC and BSP. Transient cotransfection of promoter-luciferase constructs and connexin expression vectors demonstrated that OC and BSP gene transcription was down-regulated by Cx45 cotransfection in ROS 17/2.8 and MC3T3-E1 cells, in association with a decrease in dye coupling. Conversely, cotransfection of Cx43 in UMR 106-01 cells up-regulated OC and BSP gene transcription. Activity of other less specific osteoblast promoters, such as osteopontin and osteonectin, was less sensitive to changes in gap junctional communication. Thus, altering gap junctional permeability by manipulating the expression of Cx43 and Cx45 in osteoblastic cells alters transcriptional activity of osteoblast-specific promoters, presumably via modulation of signals that can diffuse from cell to cell. A communicating intercellular network is required for the full elaboration of a differentiated osteoblastic phenotype.