Lukianov, Stefan
(2013)
A Transgenic Mouse Model of Merkel Cell Virus Small Tumor Antigen.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Merkel
cell
carcinoma
(MCC),
a
primary
cutaneous
neoplasm,
originates
in
the
mechanoreceptor
Merkel
cells
in
the
basal
layer
of
the
epidermis.
Risk
factors
include
UV
exposure,
advanced
age
and
immunosuppression,
suggesting
an
infectious
etiology.
MCC
incidence
in
the
US
is
rising,
with
approximately
1500
cases
per
year.
The
non-‐enveloped,
double-‐stranded
DNA
Merkel
cell
polyomavirus
(MCV)
is
responsible
for
approximately
80%
of
MCC
cases.
The
virus
was
discovered
by
subjecting
MCC
tissue
samples
to
digital
transcriptome
subtraction,
in
which
mRNA
is
isolated,
the
human
transcripts
subtracted
in
silico
and
the
remaining
transcripts
compared
to
viral
sequences.
MCV
expresses
differentially
spliced
Large
(LT),
Small
(sT)
and
57
kT
tumor
antigens
from
the
T
antigen
early
locus,
similar
to
other
polyomaviruses
such
as
SV40.
Both
LT
and
sT
are
critical
for
transformation.
LT
is
a
helicase
responsible
for
replication
of
the
viral
genome,
however
in
integrated
viral
genomes
it
is
either
truncated
or
mutated
to
eliminate
its
replicative
functions.
sT
contributes
to
transformation
via
hyperphosphorylation
and
inhibition
of
the
cap-‐dependent
translation
inhibitor
4E-‐BP1.
The
function
of
57
kT
remains
unknown.
Knockdown
of
LT
induces
necroptosis
of
MCV-‐
positive
MCC
cells,
whereas
sT
expression
in
rodent
Rat-‐1
cells
is
transformative.
v
Being
that
sT
is
the
transformative
agent
in
rodent
cells,
it
would
be
of
interest
to
develop
a
mouse
model
expressing
sT
in
a
tissue-‐specific
manner
to
determine
whether
tumor
formation
occurs.
Indeed,
several
mouse
models
of
SV40
T
antigen
have
been
developed
over
the
past
decades,
each
resulting
in
tissue-‐specific
tumor
formation.
We
developed
a
MCV
sT
transgenic
mouse
model,
in
which
a
lox-‐stop-‐lox
sT
is
expressed
via
an
ER-‐inducible
Cre
gene
under
the
control
of
the
ubiquitin
promoter.
Upon
tamoxifen-‐
induced
MCV
sT
expression,
ER-‐Cre-‐positive
mice
demonstrate
severe
weight
loss,
ruffled
fur
and
a
hunched
posture,
necessitating
euthanasia.
Western
blotting
reveals
sT
expression
in
several
tissues,
whereas
TUNEL
staining
shows
significant
cell
death.
While
we
were
unable
to
observe
transformation,
we
believe
this
drastic
phenotype
demonstrates
the
validity
of
our
MCV
sT
transgenic
mouse
model
and
warrants
further
investigation
into
the
mechanism
of
death.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
2 December 2013 |
| Date Type: |
Publication |
| Defense Date: |
1 October 2013 |
| Approval Date: |
2 December 2013 |
| Submission Date: |
25 November 2013 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
53 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Integrative Molecular Biology |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Transgenic
Merkel
Tumor |
| Date Deposited: |
02 Dec 2013 16:13 |
| Last Modified: |
19 Dec 2016 14:41 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/20100 |
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