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A random Abstract
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Identification of allelic variants of pendrin (SLC26A4) with loss and gain of function.
[pendred syndrome]
Pendrin
is
a
multifunctional
anion
transporter
that
exchanges
chloride
and
iodide
in
the
thyroid
,
as
well
as
chloride
and
bicarbonate
in
the
inner
ear
,
kidney
and
airways
.
Loss
or
reduction
in
the
function
of
pendrin
results
in
both
syndromic
(
Pendred
syndrome
)
and
non-syndromic
(
non-syndromic
enlarged
vestibular
aqueduct
(
ns-
EVA
)
)
hearing
loss
.
Factors
inducing
an
up-regulation
of
pendrin
in
the
kidney
and
the
lung
may
have
an
impact
on
the
pathogenesis
of
hypertension
,
chronic
obstructive
pulmonary
disease
(
COPD
)
and
asthma
.
Here
we
characterize
the
ion
transport
activity
of
wild-
type
(
WT
)
pendrin
and
seven
of
its
allelic
variants
selected
among
those
reported
in
the
single
nucleotide
polymorphisms
data
base
(
dbSNPs
)
,
some
of
which
were
previously
identified
in
a
cohort
of
individuals
with
normal
hearing
or
deaf
patients
belonging
to
the
Spanish
population
.
WT
and
mutated
pendrin
allelic
variants
were
functionally
characterized
in
a
heterologous
over-expression
system
by
means
of
fluorometric
methods
evaluating
the
I
(
-
)
/
Cl
(
-
)
and
Cl
(
-
)
/
OH
(
-
)
exchange
and
an
assay
evaluating
the
efflux
of
radiolabeled
iodide
.
The
transport
activity
of
pendrin
P
70
L
,
P
301
L
and
F
667
C
is
completely
abolished
;
pendrin
V
609
G
and
D
687
Y
allelic
variants
are
functionally
impaired
but
retain
significant
transport
.
Pendrin
F
3
54
S
activity
is
indistinguishable
from
WT
,
while
pendrin
V
88
I
and
G
740
S
exhibit
a
gain
of
function
.
Amino
acid
substitutions
involving
a
proline
always
result
in
a
severe
loss
of
function
of
pendrin
.
Two
hyperfunctional
allelic
variants
(
V
88
I
,
G
740
S
)
have
been
identified
,
and
they
may
have
a
contributing
role
in
the
pathogenesis
of
hypertension
,
COPD
and
asthma
.
