Expression of the HOX-2.3 homeobox gene in human lymphocytes and lymphoid
tissues
Y Deguchi, JF Moroney and JH Kehrl
Laboratory of Immunoregulation, National Institute of Allergy and
Infectious Diseases, National Institute of Health, Bethesda, MD 20892.
Homeobox proteins are sequence-specific DNA-binding proteins initially
implicated in the control of gene expression in developing tissues;
however, there is increasing evidence that these proteins are important in
gene regulation in adult tissues. A cDNA for the homeobox gene HOX- 2.3 was
isolated from an adult human B-lymphocyte cDNA library. Northern blot
analysis showed expression of a 1.1 and a 1.6 kb messenger RNA (mRNA) in a
human B-cell line. RNase protection assays demonstrated variable expression
in both human B- and T-cell lines. Virally transformed and nontransformed
lymphocyte cell lines expressed HOX-2.3 transcripts. Essentially no
transcripts were found in unactivated normal B and T lymphocytes; however,
B-cell activation with Staphylococcus aureus Cowan strain I and phorbol
myristate acetate (PMA) or T-cell activation with phytohemagglutinin and
PMA were accompanied by a rapid induction of HOX-2.3 expression even in the
presence of the protein synthesis inhibitor, cycloheximide. In situ
hybridization was performed to examine HOX-2.3 expression in lymphoid
tissues. HOX-2.3 mRNA was detected in the thymic cortex from an 8-year- old
child, in the germinal centers in adult tonsil, and in a limited number of
hematopoietic cells from the bone marrow. These findings suggest the
involvement of HOX-2.3 in regulating gene transcription not only in
developing tissues but in hematopoietic and lymphoid tissues as well.
Volume 78,
Issue 2,
pp. 445-450,
07/15/1991
Copyright © 1991 by The American Society of Hematology
