Matsushita Hiroshi, Blackburn Michael L, Klineberg Eric, Zielinska-Kwiatkowska Anna, Bolander Mark E, Sarkar Gobinda, Suva Larry J, Chansky Howard A, Yang Liu
Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Biochem Biophys Res Commun. 2007 May 4;356(2):411-7. doi: 10.1016/j.bbrc.2007.02.159. Epub 2007 Mar 9.
During the differentiation of chondroprogenitors into mature chondrocytes, the alternative splicing of collagen genes switches from longer isoforms to shorter ones. To investigate the underlying mechanisms, we infected mouse ATDC5 chondroprogenitor cells with retrovirus for stable expression of two closely related SR splicing factors. RT-PCR analysis revealed that TASR-1, but not TASR-2, influenced alternative splicing of type II and type XI collagens in ATDC5 cells. The effect of TASR-1 on splicing could be reversed with the addition of insulin. Results from our microarray analysis of ATDC5 cells showed that TASR-1 and TASR-2 differentially affect genes involved in the differentiation of chondrocytes. Of special interest is the finding that TASR-1 could down-regulate expression of type X collagen, a hallmark of hypertrophic chondrocytes. Immunohistostaining demonstrated that TASR-1 protein is more abundantly expressed than TASR-2 in mouse articular chondrocytes, raising the possibility that TASR-1 might be involved in phenotype maintenance of articular chondrocytes.
在软骨祖细胞分化为成熟软骨细胞的过程中，胶原蛋白基因的可变剪接从较长的异构体转变为较短的异构体。为了研究其潜在机制，我们用逆转录病毒感染小鼠ATDC5软骨祖细胞，以稳定表达两种密切相关的SR剪接因子。RT-PCR分析显示，TASR-1而非TASR-2影响了ATDC5细胞中II型和XI型胶原蛋白的可变剪接。添加胰岛素后，TASR-1对剪接的影响可以逆转。我们对ATDC5细胞进行的微阵列分析结果表明，TASR-1和TASR-2对软骨细胞分化相关基因有不同影响。特别值得关注的是，TASR-1可以下调X型胶原蛋白的表达，而X型胶原蛋白是肥大软骨细胞的一个标志。免疫组织化学染色表明，在小鼠关节软骨细胞中，TASR-1蛋白的表达比TASR-2更丰富，这增加了TASR-1可能参与关节软骨细胞表型维持的可能性。
