Expression of synaptotagmin viii in rat kidney.
Kishore, Bellamkonda K., James B. Wade, Kristel Schorr, Takeaki Inoue,
B[acute]eatrice Mandon, and Mark A. Knepper.
Laboratory of Kidney and Electrolyte Metabolism, National Heart,
Lung and Blood Institute, National Institutes of Health, Bethesda, MD
20892-0951. Department of Physiology, University of Maryland School
of Medicine, Baltimore, MD 21201
APStracts 5:0045F, 1998.
The synaptotagmins are a family of integral membrane proteins proposed
to function as regulators of both exocytosis and endocytosis. Here,
we have used immunochemical techniques and RT-PCR to assess sites of
renal expression of synaptotagmin VIII. A polyclonal antibody was
raised to a synthetic peptide corresponding to the carboxyl terminal
21 amino acids of mouse synaptotagmin VIII. On immunoblots of
membrane fractions from renal cortex and medulla (and in several
other tissues), the antibody labeled a 52 kDa band (absent with pre
-immune IgG). Immunofluorescence localization was carried out in
tissue sections from rat kidney. The synaptotagmin VIII antibody
labeled early proximal tubules, thin ascending limbs, thick ascending
limbs, connecting tubules, and collecting ducts. In collecting ducts,
both type A and B intercalated cells exhibited basolateral labeling,
while principal cells were labeled chiefly in the apical and
subapical portion of the cells. Thick ascending limbs were labeled in
both the basolateral and apical regions. RT-PCR experiments using
total RNA extracted from cortex and medulla or microdissected inner
medullary collecting ducts gave a single band of appropriate size.
Sequencing of the PCR product confirmed that the amplified target is
synaptotagmin VIII. We conclude that synaptotagmin VIII is broadly
expressed among renal tubule epithelia, raising the possibility that
it is involved in regulation of transport and/or cell remodeling at
several sites in the nephron and collecting duct.
Received 9 July 1997; accepted in final form 12 February 1998.
APS Manuscript Number F225-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 19 February 1998