Expression of Exon 2 of Type II Procollagen mRNA in Primary Culture of Rat Chondrocyte

Kim, Tae Gyun; Seong, In Ho; Kim, Sung Tae; Kim, Hee Joong; Seong, Sang Cheol

Abstract

Type II procollagen mRNA exists in two forms, type II A and II B, by alternative splicing of exon 2. Type II A procollagen mRNA has been known to be expressed in chondroprogenitor, periosteal and perichondrial cells, whereas type II B procollagen mRNA in chondrocytes. Previous reports indicate that both types of procollagen mRNA exist in primary culture of rat chondrocyte. In this study, the time-dependent change in the type II A and II B mRNA expression in the primarily cultured rat chondrocytes was analyzed using reverse transcription polymerase chain reaction (RT-PCR) and Northern hybridization. Most chondrocytes in the early stage of primary cell culture were oval or polygonal in their shape. However, since 2 to 3 weeks of primary cell culture, most cells changed their shapes into fibroblast-like or ameboid cells. RT-PCR revealed that until 1 week of culture, the expression of the type II B mRNA was greater than that of the type II A. After 2 weeks of culture, the expression of the type II A mRNA became greater. Northern blot analysis showed a gradual decrease in the expression of the total type II procollagen mRNA with time of culture. On the other hand, the expression of the type II A procollagen mRNA increased significantly at 2 weeks and the increased level was maintained thereafter. This study confirmed that in primary culture of chondrocyte, the cells changed their morphological and molecular characteristics at the relatively early stage. This study implicates that in order to delineate the changes of phenotypes of chondrocytes, quantitative analysis of both type II A and II B procollagen mRNA is necessary instead of performing analysis of total type II procollagen mRNA.