Haematopoiesis involves the differentiation of a self-renewing stem cell in
to all of the lineages found in circulating blood. Myb-Ets transformed chic
ken blastoderm cells (MEPs) have many of the characteristics of multipotent
haematopoietic cells and represent a useful model system for the study of
haematopoiesis. The proline-rich homeodomain protein (PRH) has previously b
een shown to be expressed in the haematopoietic compartment. In this report
we show that PRH mRNA and protein levels are down regulated as MEPs differ
entiate along the myelomonocytic and erythrocytic lineages. In contrast, PR
H mRNA and protein levels remain high as MEPs differentiate toward the thro
mbocytic lineage. Over-expression of full length PRH in MEPs inhibits their
transformation and/or proliferation. However, the over-expression of N-ter
minally truncated PRH proteins results in normally proliferating cells that
are predominantly differentiated along the myelomonocytic and eosinophilic
lineages. These results suggest that PRH plays a role in the proliferation
and differentiation of haematopoietic cells. (C) 2000 Elsevier Science Ltd
. All rights reserved.