Ns. Dejneka et al., LOCALIZATION AND CHARACTERIZATION OF STANNIN - RELATIONSHIP TO CELLULAR-SENSITIVITY TO ORGANOTIN COMPOUNDS, Neurochemistry international, 31(6), 1997, pp. 801-815
The cDNA encoding the protein stannin was isolated previously via subt
ractive hybridization, using differential expression after trimethylti
n (TMT) intoxication, as a basis for isolating mRNA which may be expre
ssed in TMT-sensitive cells. Initial characterization revealed a novel
gene product which was differentially expressed in several tissues se
nsitive to TMT. In the current study, biochemical and molecular techni
ques were used to quantitate stannin expression at the cellular and su
bcellular Levels. Northern blot analysis showed that the stannin 3.0 k
b mRNA transcript was present, in decreasing amounts, in: spleen, hipp
ocampus, neocortex, cerebellum, striatum, midbrain, kidney and lung. L
iver, heart, skeletal muscle and testis showed no detectable expressio
n of stannin mRNA. Immunoblot analysis using antipeptide antisera rais
ed against stannin indicated a high level of expression in spleen, fol
lowed by brain and kidney. Stannin mRNA was present during early brain
development and consolidated by post-natal day (PND) 20 to patterns a
nd levels seen in adults. In situ hybridization studies showed widespr
ead neuronal expression of stannin mRNA at PND 1, which shifted to a r
estricted pattern of expression in specific regions by PND 20. Stannin
was partially purified from rodent brain and spleen using cation exch
ange, sizing and hydrophobic interaction chromatography. It behaved as
a monomer throughout purification. Stannin was also expressed in a ba
culovirus system, using a series of constructs containing the entire c
DNA, 1.0 kb of DNA flanking the open reading frame, and a 400 bp open
reading frame minimal construct. While all constructs expressed stanni
n, the best expression was seen with the entire cDNA. Based on current
findings, we suggest that stannin expression is necessary but not suf
ficient for TMT toxicity. (C) 1997 Elsevier Science Ltd. All rights re
served.