Submitted on July 12, 2005
Accepted on July 31, 2005
The UT-A Urea Transporter Promoter, UT-A
, Targets Principal Cells of the Renal Inner Medullary Collecting Duct
Robert A. Fenton1*, Adetola Shodeinde1, and Mark A. Knepper1
1 Laboratory of Kidney and Electrolyte Metabolism, National Institutes of Health, Bethesda, MD, USA
* To whom correspondence should be addressed. E-mail: ROFE{at}ana.au.dk.
The urea transporters, UT-A1 and UT-A3, two members of the UT-A gene family, are localized to
the terminal portion of the inner medullary collecting duct (IMCD). In this manuscript, we demonstrate that
4.2-kb of the 5'-flanking region of the UT-A gene (UT-A
promoter) is sufficient to drive the IMCD-specific
expression of a heterologous reporter gene, 
-galactosidase (-Gal), in transgenic mice. RT-PCR,
immunoblotting and immunohistochemistry demonstrate that within the kidney, transgene expression is
confined to the terminal portion of the IMCD. Co-localization studies with aquaporin 2 show that expression
is localized to the principal cells of the IMCD2 and IMCD3 regions. Utilizing -Gal activity assays, we
further show that within the kidney, the -Gal transgene can be regulated by both water restriction and
glucocorticoids, similar to the regulation of the endogenous UT-A gene. These results demonstrate that
4.2-kb of the UT-A promoter is sufficient to drive expression of a heterologous reporter gene in a tissue-specific
and cell-specific fashion in transgenic mice.
