PU.1

PU.1 is an Ets-family transcription factor, which regulates the expression of immunoglobulin and other genes that are important for B-cell development. Absence of PU.1 results in a block in the early stage of B-cell development. PU.1 binds the 3' enhancer region of both immunoglobulin light chains, the intron enhancer region of immunoglobulin heavy chain, the promoter regions of several immunoglobulin variable genes and the promoter region of J chain. It is crucial to the expression of CD20, CD72 and CD79a. It acts in concert with other transcription factors including Pip, c-jun and c-fos. It also targets genes which include major histocompatibility class II, interleukin-5 receptor a and PU.1 itself, the promoter or enhancer regions of at least 24 myelomonocytic genes and four megakaryocytic genes. High levels of PU.1 expression promote macrophage differentiation, low levels promote lymphocytic differentiation and the combination with GATA promotes erythroid differentiation.

Expression

• B-lymphocytes, immature and mature, including mantle cells and most cells of the germinal centre, but not plasma cells

• Histiocytes, including plasmacytoid monocytes.

The lack of PU.1 protein expression in classical Hodgkin lymphoma likely contributes to the lack of immunoglobulin expression and incomplete B-cell phenotype characteristic of the Reed-Sternberg cells.

1Torlakovic, E., A. Tierens, et al. (2001). “The transcription factor PU.1, necessary for B-cell development is expressed in lymphocyte predominance, but not classical Hodgkin's disease.” Am J Pathol 159(5): 1807-14.

This page last revised 23.5.2004.

©SMUHT/PW Bishop