Download Regulation of Bovine Parathyroid Hormone (Pth) Gene Expression

Medical Research Society
36r
("superficial" injury) molsidomine reduced intimal
(p<O.OI) and medial (p<0.05) SMC proliferation, but when
it was ruptured ("deep" injury) proliferation w a s
uninfluenced by molsidomine. Molsidomine failed to
reduce intimal thickening. These results provide the first
evidence that NO inhibits platelet adhesion and SMC
proliferation in uiza at sites of vascular injury. They also
show that intimal SMC proliferation is maximal at sites of
IEL rupture and that the anti-proliferativeeffects of N O are
overwhelmed in the presence of deep injury.
regulation by caicium was investigated and the
Vitamin D, response element (VDRE) in the gene
was localisad. In the former, low extracellular
calcium concentrations (0.4 a)had no effect on
steady-state
preproPTH
mRNA
levels,
but
increased
preproPTH
KIRNA
associated
with
membrane-bound polysomes by 2008 after 48 hours.
Act'inomycin D (5pg/ml) decreased steady-state
preproPTH mRNA levels measured by dot-blot
assays in cells incubated in 0 . 4 and 1.0 IM
calcium after 48 hr
incubation.
However,
actinomycin D did not abolish low calciuminduced rises in polysomal preproPTH mRNA but
increased preproPTH mRNA levels by 1.6-fold in
cells incubated in 0.4 and 1.0 UW calcium.
Sucrose density gradients confirmed increased
polysomal association of preproPTH mRNA. For
localisation of the VDRE, fragments of the PTH
gene were generated with SspI and sequenced.
Vitamin D, receptors
(VDR) were partially
purified from bovine parathyroid glands by
sucrose density ultracentrifugation and reacted
with DNA fragments in Southwestern assays. A
single band of 50 kDa was identified which was
coincident with bands obtained in Western blots.
Data from these assays indicated binding of VDR
to fragments -450 t o -350 and -700 to -450 base
pairs. This study shows regulation of PTH
synthesis at two sites: transcriptional and
translational.
INVgSTIGATION OF HERPES SIMPLEX VIRUS LATBNCI IN
TISSUE CULTURE SYSTEM
D R
S JAMIPSON
A
(Introduced by J M MODES)
HRC Virology unit, Institute of Virology, Church Street,
Glasgow Gll SJR, Scotland
14
REGUUTION OF BOVINE PARATHYROID HORMONE
(PTH) GENE EXPRESSION BY CALCIUM AND 1,25DIHYDROXYVITAMIN D, (1,25(OH),D,)
N S HAWA, J L H O'RIORDAN
and S M FARROW
Department of Medicine, University College
Medical School, London W 1 N 0 M , England
Parathyroid gland activity is regulated by
calcium which affects both transcription and
possibly
translation,
whilst
the
steroid
hormone, 1,25(0H)2D,, affects transcription of
the
gene.
In
this
study,
translational
The herpas simplex virus (HSV) is a human pathogen with
the ability to establish latency in ganglia during
primary
infection.
Reactivation gives
rise
to
serious
clinically important conditions the most
being
encephalitis and
those
in imnocanprauised
individuals.
Little is knom of the molecular
processes involved in the establishment and maintenance
or
h a
reactivation
occurs.
h i s
of
latency
investigation has established an in U model using
genetic manipulation of a mutant of HSV type 1, h i 8 1 4
which has a mutation in VMW65, a protein responsible
for the transactivation of iuumdiate early (IB) genes.
As a consequence, in1814 is strongly predisposed to
latency in tissue culture systems. By replacing an IE
gene pranoter in this mutant and pretreating cells with
human interferon a, high efficiency establishment and
reactivation of latency has been achieved. It is
possible to reactivate virus fran essentially all cells
in a culture in superinfection experiments.
Southern
hybridisation of latently infected cultures demonstrates
the presence of at least 1 copy of HSV DNA per cell,
present in a form which lacks genanic termini and
characteristic of the latent genane in vivo.
The
creation of other mutants possessing the B-galactosidase
gene has confirmed these findings. It has been shorn
that the latent genane in this model is closely
associated with the nuclear substmxture and will copurify with it. Surprisingly the latent viral genune is
not nucleosanal and by inference does not have a
chrauatin structure unlike all eukaryotic DNA.
It is
msre sensitive to digestion by micrococcal nuclease as
it progressses to the latent state yet such sensitivity
This model should
does not change on reactivation.
allow further investigation of latency and begin to
resolve questions which will facilitate the development
of therapies to diSNpt or disable it.