AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 1 142-R147, Copyright © 1997 by American Physiological Society
Temporal and spatial expression pattern of the angiotensinogen gene in mice and rats
F. Niimura, S. Okubo, A. Fogo and I. Ichikawa
Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
In situ hybridization for mouse angiotensinogen (Ao) mRNA was performed
using a Stu I-Pst I 0.43-kb fragment of exon 2 as a template to synthesize
RNA probes. The mouse Ao mRNA expression patterns were different from those
reported for rats. Ao mRNA was expressed in the fetal liver as early as
12.5 days postcoitus, and the liver remained the predominant organ of its
expression in utero. Within the developing kidney, Ao mRNA was demonstrated
at 17.5 days postcoitus in the proximal straight tubules undergoing loop
formation in the medulla. In the matured mouse kidney, the expression site
is within the outer stripe of outer medulla, hence identified as the pars
recta, not proximal convoluted tubules. Additional studies revealed that,
in rats also, Ao mRNA was localized in the pars recta. This was in contrast
to previously published results that showed that Ao mRNA was localized
primarily in the proximal convoluted tubules in rats. Thus the pars recta
appears to be an important intrarenal source of Ao for both rats and mice
throughout pre- and postnatal periods, whereas the liver can be the major
extrarenal source in utero in mice, but not in rats.
