DIFFERENTIAL EXPRESSION OF PROTEIN-TYROSINE KINASES IN THE CORTICAL AND MEDULLARY THYMIC EPITHELIAL-CELL LINES

Expression of protein tyrosine kinase (PTK) was evaluated and compared between cortical and medullary thymic epithelial cell (TEC) lines, TE C 14C18 and TEC 1C6, respectively. Reverse transcription-polymerase ch ain reaction (RT-PCR) methods using degenerate primers for conserved s equence in catalytic domain of PTK revealed the expression of 13 kinds of PTKs in these cell lines. These PTKs included 6 receptor and 7 non -receptor types. In the next step, we compared the intensity of mRNA e xpression level of these kinases between cortical and medullary TEC li nes. Tyrosine kinases of receptor type were differentially expressed b etween cortical and medullary TEC lines; e.g., mRNA expression of flg was observed more intensively in the cortical TEC line than in the med ullary one, while mRNA expression of bek, met and sky was vice versa. On the other hand, expression of non-receptor tyrosine kinases, includ ing four JAK-tyk family members, are comparable in both lines. These r esults suggested that these PTKs, especially of receptor type, might p lay an important role in the development of the thymic microenvironmen t. (C) 1995 Academic Press, Inc.