Multiple isoforms of PAX5 are expressed in both lymphomas and normal B-cells.

The transcription factor Pax5 plays a critical role in B cell development. It has been shown that alternative splicing of its gene ( PAX5) produces several distinct transcripts that modify the amino acid sequence of the putative Pax5 proteins. Subsequent studies have attempted to correlate the expression of PAX5 isoforms with certain B-cell lymphomas, the conclusions of which suggest that altered isoform expression is involved in lymphomagenesis. However, in the absence of definitive data for PAX5 isoform expression patterns in normal B cells it is difficult to confirm whether aberrant isoform expression can indeed be correlated with disease. Using a high-resolution method of analysis of reverse transcription polymerase chain reaction products, we sought to analyse the expression of the different PAX5 isoforms in normal B-cells as well as a number of B-cell lymphoma and chronic lymphocytic leukaemia cases. It was found that multiple PAX5 isoforms were expressed in both normal and malignant B cells. Immunodetection and polysomal RNA analyses also confirmed that the different PAX5 mRNAs were translated into their corresponding proteins. No consistent deregulation of PAX5 isoform expression was observed in B-cell lymphomas, but rather, complex isoform expression patterns were found in normal B cell as well as B-cell lymphoma and CLL cases. [ABSTRACT FROM AUTHOR]