We have used an embryonic endothelial cell line (IEM cells) as an experimen
tal system for identifying and characterizing new molecules which are regul
ated during blood vessel development. A novel gene isolated from IEM cells,
tubedown-1 (tbdn-1), is expressed at high levels in unstimulated IEM cells
and is down-regulated during formation of capillary tube structures by the
IEM cells induced by basic fibroblast growth factor (bFGF) and leukemia in
hibitory factor (LIF) in vitro. Tbdn-1 is also downregulated in M1 myeloid
leukemia cells after differentiation in response to LIF in vitro. Tbdn-1 is
homologous to the yeast NAT-1 N-terminal acetyltransferases and encodes a
novel protein of similar to 69 kDa associated with an acetyltransferase act
ivity. Levels and distribution of tbdn-1 expression are regulated in both e
ndothelial and hematopoietic cells during development in tissues such as th
e yolk sac blood islands, heart, and liver blood vessels. In the adult, tbd
n-1 expression is low or undetected in most organs examined with the except
ion of the atrial endocardium, the endothelial and myeloid compartments of
bone marrow, and the remodeling vascular bed of atretic ovarian follicles.
The distribution and regulation of expression of tbdn-1 suggest that this n
ovel acetyltransferase may be involved in regulating vascular and hematopoi
etic development and physiologic angiogenesis. Dev Dyn 2000;218:300-315. (C
) 2000 Wiley-Liss, Inc.