Expression of lrp (transmembrane type tyrosine phosphatase) mrna
along rat nephron segments.
Kaneko, Tetsuya, Toshiki Moriyama, Enyu Imai, Yoshitaka Akagi, Makoto
Arai, Takuya Inoue, Chen Xia, Tamio Noguchi, Takenobu Kamada, and
Naohiko Ueda.
First Department of Medicine, and Department of Nutrition and
Physiological Chemistry. Osaka University School of Medicine, 2-2
Yamadaoka, Suita, Osaka 565, Japan
APStracts 2:0031F, 1995.
Protein phosphorylation on tyrosine residues is one of the main cell
signaling mechanisms. Cellular phosphotyrosyl levels are regulated by
the activities of protein tyrosine kinases (PTK) and protein tyrosine
phosphatases (PTPase). We have previously reported cDNA cloning of
several types of PTPase from rat kidney, including LRP (leucocyte
common antigen related protein; transmembrane type tyrosine
phosphatase also called $QUOTRPTP[alpha]$QUOT). LRP mRNA was shown to
be abundant in the kidney, however our understanding on the
functional role of LRP in the kidney is very limited. To get closer
insight into the function of LRP in the kidney, our first approach
was to reveal its mRNA distribution along rat nephron segments. Large
signals were found in innermedulla by Northern blot analysis. By
using a reverse transcription and polymerase chain reaction assay
(RT-PCR) of individual microdissected tubule segments along the
nephron (proximal convoluted tubule; PCT, medullary thick ascending
limb; MTAL, cortical collecting duct; CCD, outermedullary collecting
duct; OMCD, and innermedullary collecting duct; IMCD) and glomeruli;
Glm, we revealed intrarenal localization of LRP mRNA. LRP mRNA was
detected in all nephron segments tested, but relatively rich in IMCD.
Rank of order of the signal intensity was;
IMCD>PCT=OMCD>CCD>MTAL=Glm. Immunohistochemistry also revealed
that LRP was abundant in IMCD. This pattern of expression gives rise
an interesting possibility that LRP might involve in the specific
renal tubule function such as urinary concentrating mechanism,
however further study is required to discuss the function of LRP in
more detail.
Received 5 December 1994; accepted in final form 19 January 1995.
APS Manuscript Number F428-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.