Expression profile of protein tyrosine kinase genes in human osteoarthritis chondrocytes

Objective: To determine the expression profile of protein kinase (PK) and p rotein tyrosine kinase (PTK) genes in human primary osteoarthritis (OA) cho ndrocytes and to compare it with that of immortalized human chondrocytes T/ C 28a4 with a view to learning whether T/C 28a4 cells can be used for eluci dating signal transduction pathways in human chondrocytes. Design: We used the Atlas Human cDNA Array and a method based on PCR with d egenerate primers to analyse the expression profile of protein kinase genes in primary human CA chondrocytes and compared it with that of immortalized human chondrocyte cell line T/C 28a4 using RT-PCR and Western blotting. Results: A total of 21 PTK genes were identified and several of these have never been shown to be expressed in human CA chondrocytes. Comparative expr ession analysis of some selected kinase genes showed that the mRNA expressi on pattern of many protein kinase genes in CA chondrocytes was identical to that of T/C 28a4 cells. However, there were differences in the level of pr otein expression of selected protein kinases in these cells. For example, m RNA expression of the novel kinase HCK was detected in CA chondrocytes and in the cell lines analysed but by Western blotting HCK protein was not dete cted in OA chondrocytes. In these studies, we also identified a novel mutan t form of the discoidin domain receptor 2 (DDR2) transcript from chondrocyt e-like cell line HTB-94. Conclusions: Our results provide novel information about protein kinase gen e expression in OA chondrocytes and indicate that the transformed chondrocy te cell line T/C 28a4 may be suitable for elucidating signal transduction p athways in chondrocytes and to investigate how they regulate chondrocyte fu nction in inflammatory and degenerative joint diseases. (C) 2001 OsteoArthr itis Research Society International.