Up-regulation of the Pit-2 Phosphate Transporter/Retrovirus
Receptor by Protein Kinase C
*
Zsolt
Jobbagy
,
Zoltan
Olah
§,
Gyorgy
Petrovics
,
Maribeth
V.
Eiden¶,
Betsy D.
Leverett
,
Nicholas M.
Dean**, and
Wayne B.
Anderson

From the
Laboratory of Cellular Oncology, National
Cancer Institute, and ¶ Laboratory of Cellular and Molecular
Regulation, National Institute of Mental Health, National Institutes of
Health Bethesda, Maryland 20892,
Center for Biologics
Evaluation and Research, Food and Drug Administration,
Bethesda, Maryland 20892, and ** Department of Pharmacology, ISIS
Pharmaceuticals, Carlsbad Research Center,
Carlsbad, California 92008
 |
ABSTRACT |
The membrane receptors for the gibbon ape
leukemia retrovirus and the amphotropic murine retrovirus serve normal
cellular functions as sodium-dependent phosphate
transporters (Pit-1 and Pit-2, respectively). Our earlier studies
established that activation of protein kinase C (PKC) by treatment of
cells with phorbol 12-myristate 13-acetate (PMA) enhanced
sodium-dependent phosphate (Na/Pi)
uptake. Studies now have been carried out to determine which type of
Na/Pi transporter (Pit-1 or Pit-2) is regulated by PKC and
which PKC isotypes are involved in the up-regulation of
Na/Pi uptake by the Na/Pi transporter/viral
receptor. It was found that the activation of short term (2-min)
Na/Pi uptake by PMA is abolished when cells are infected
with amphotropic murine retrovirus (binds Pit-2 receptor) but not with
gibbon ape leukemia retrovirus (binds Pit-1 receptor), indicating that
Pit-2 is the form of Na/Pi transporter/viral receptor regulated by PKC. The PKC-mediated activation of Pit-2 was blocked by
pretreating cells with the pan-PKC inhibitor bisindolylmaleimide but
not with the conventional PKC isotype inhibitor Gö 6976, suggesting that a novel PKC isotype is required to regulate Pit-2. Overexpression of PKC
, but not of PKC
, -
, or -
, was found to mimic the activation of Na/Pi uptake. To further
establish that PKC
is involved in the regulation of Pit-2, cells
were treated with PKC
-selective antisense oligonucleotides.
Treatment with PKC
antisense oligonucleotides decreased the
PMA-induced activation of Na/Pi uptake. These results
indicate that PMA-induced stimulation of Na/Pi uptake by
Pit-2 is specifically mediated through activation of PKC
.
 |
INTRODUCTION |
Protein kinases, including members of the protein kinase C family,
regulate numerous biological functions, including intracellular protein
trafficking and the activities of different ion transporters (1).
Previously, we showed that sodium-dependent phosphate (Na/Pi)1
transport was stimulated by protein kinase C (PKC) and inhibited by
protein kinase A in NIH 3T3 cells. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, was found to cause a rapid (within 10 min)
stimulation of short term Na/Pi uptake (2). However, at
that time the identity of the Na/Pi transporter stimulated in response to PMA was not known, and this prevented further
characterization of the PKC-mediated activation of the transporter.
More recently, cell surface receptors for the gibbon ape leukemia virus
(Glvr-l and Pit-1) and the amphotropic murine leukemia virus (Ram-1,
Ear, and Pit-2) were demonstrated to serve as Na/Pi
transporters in the normal cellular physiology of diverse cell types
(3-5).
Amino acid sequence data obtained for the Pit-1 and Pit-2
receptor-transporters has revealed multiple sites potentially
susceptible to phosphorylation by protein kinases, including PKC, which
are found within the hydrophilic cytoplasmic domain of both
transporters between residues 250 and 450. Indeed, parathyroid
hormone-induced regulation of transporter function mediated through
activation of protein kinase A and PKC has been described for type I
and II Na/Pi transporters present in kidney brush-border
membranes (6). In addition to parathyroid hormone, prostaglandin E2, insulin-like growth factor 1, and vitamin D3 all have been
reported to regulate Na/Pi uptake through activation of PKC
in osteoblasts, another cell type that uses high levels of inorganic
phosphate (7-10). It also has been suggested that a phospholipase
C
-PKC signaling pathway is responsible for the up-regulated
Pi transport observed with platelet-derived growth factor
treatment of osteoblast-like cells. (11-13). In osteoblasts it is
possible that the more ubiquitously expressed type III
Na/Pi transporters, such as Pit-1 and Pit-2, might be
involved in the PKC-regulated uptake of Pi. Conversely, activation of PKC has been reported to inhibit Pi uptake in
opossum kidney cells, which may indicate different regulation of the
renal type I and II transporters (6, 14, 15). These differences in
PKC-mediated regulation of Pi uptake may be a consequence
of different expression patterns of either PKC and/or Na/Pi
transporter isotypes in different cell lines.
One of the major difficulties in determining which PKC isotypes are
involved in regulating Na/Pi transport is that different cell types express various combinations of PKC isoforms. Protein kinase
C is a family of at least 11 serine- and threonine-specific phosphotransferase isoenzymes that are characterized by a high degree
of homology in their catalytic and cysteine-rich domains (1). Although
the possible role(s) of different PKC isozymes in cell growth and
differentiation has been well studied (for review, see Ref. 1), much
less is known of their potential involvement in modulating
intracellular trafficking of transmembrane receptors and up-regulation
of ion transporters. In this study we have sought to determine which
type of Na/Pi transporter/viral receptor is regulated by
PMA activation of PKC and which PKC isotype(s) may be involved in the
up-regulation of Na/Pi uptake in NIH 3T3 cells. The results
presented in this communication indicate that the Pit-2
Na/Pi transporter/viral receptor is specifically activated by PMA stimulation of PKC
.
 |
EXPERIMENTAL PROCEDURES |
Materials--
Dulbecco's modified Eagle's medium (DMEM) and
fetal calf serum were purchased from Biofluids Inc. (Rockville, MD).
PMA, bisindolylmaleimide, and Gö 6976 were products of Calbiochem
(San Diego, CA). 32P-Labeled monopotassium phosphate was
from ICN (Costa Mesa, CA). The PKC isotype-specific antisense and
scrambled oligonucleotides (ISIS 17260, PKC
antisense; ISIS 17261, PKC
scrambled control) were from ISIS Pharmaceuticals. PKC
isotype-specific polyclonal antibodies were purchased from Life
Technologies, Inc.; PKC
-specific monoclonal antibodies were from
Upstate Biotechnology (Lake Placid, NY); and PKC
- and
PKC
-specific monoclonal antibodies were from Transduction
Laboratories (Lexington, KY).
Cell Culture--
Retrovirus-infected and vector-transduced NIH
3T3 cells were cultured in DMEM supplemented with 10% fetal calf
serum. After the cells reached confluency, the medium was changed to
serum-free DMEM for 24 h. To induce overexpression of any ectopic
gene products, the cells were incubated in the presence or absence of
20 µM zinc acetate, as indicated, to induce the
up-regulation of the metallothionein promoter of the p
MTH vector
(16).
Generation of Overexpressor Cell Lines--
The construction of
expression vectors and establishment of PKC overproducer cell lines
were carried out as described previously (17). The PKCa, -
, -
,
and -
plasmid constructs were prepared in the p
MTH vector, and
overexpressor cell lines were established following protocols described
elsewhere (18). Individually picked colonies (10 from each
transfection) were selected and combined for further studies to
eliminate potential cloning artifacts. These mixed populations of
overexpressor cells were used only through 12-14 passages in culture
to negate possible outgrowth of one particular clone.
Phosphate Uptake Measurement--
Sodium-dependent
phosphate uptake was determined as described previously (2).
Retrovirus Infections--
NIH 3T3 murine fibroblasts and mink
lung fibroblasts (ATCC CCL 64) were maintained in DMEM supplemented
with 10% (v/v) fetal bovine serum. NIH 3T3 cells were infected with
wild type amphotropic murine retrovirus (A-MuLV) strain 4070A or the
57A Friend strain of ecotropic MuLV (E-MuLV). Mink fibroblasts
expressing gibbon ape leukemia retrovirus (GALV)-competent PiT-1 were
infected with wild type A-MuLV strain 4070A or infected with a GALV
strain (SEATO), as described previously (4). Productive infection was
monitored by measuring the reverse transcriptase activity found in the
cell media of the infected cells (19).
Antisense Oligonucleotide Treatment--
NIH 3T3 fibroblasts
were cultured in 150-mm tissue culture dishes until they reached
~80% confluency. The cells then were harvested by trypsinization,
washed with DMEM, and resuspended in 400 µl of cytosalt
electroporation buffer (75% cytosalts (120 mM KCI, 0.15 mM CaC12, 10 mM
K2HP04, pH 7.6, 6.5 mM
MgCl2) and 25% Opti-MEM I). Twenty-µl aliquots of PKC
isotype-specific or scrambled control oligonucleotides were added to
the cells resuspended in prechilled BTX disposable electroporation
cuvettes (P/N 640; 4-mm gap) to reach the indicated concentrations and
then incubated on ice for 5 min. The oligonucleotides indicated were
introduced into the cells by electroporation with a BTX Electro Square
Porator (settings: low voltage mode, 99 msec; charge voltage, 475 V;
pulse length, 1 msec; number of pulses, 4). The electroporated cells were kept at room temperature for 10 min and then seeded onto 100-mm
tissue culture plates for immunoblot studies and onto 24-well plates
for Pi uptake measurements. Western blot analysis of PKC isotypes and Pi uptake studies were carried out 24 h
after introduction of the antisense oligonucleotides.
Western Blot Analysis--
Proteins were separated by precast
4-20% SDS-polyacrylamide gel (Owl Separation Systems, Portsmouth, NH)
electrophoresis and electrophoretically transferred from the gel onto
Protran membranes (Schleicher & Schuell, Keene, NH), and immunoreactive
proteins were detected as described elsewhere (16, 18).
 |
RESULTS AND DISCUSSION |
Most retroviruses have been found to use distinct cell surface
receptors for specific cellular recognition and infection (for review,
see Ref. 20). Furthermore, studies have revealed that the normal
cellular function of a number of these viral receptors is to serve as
membrane transport proteins (20). NIH 3T3 cells have been found to
express several of these viral receptor/transporters, including Pit-1,
Pit-2, and the cationic amino acid transporter CAT/y+, as determined by
viral infection studies and reverse transcription-polymerase chain
reaction analysis. NIH 3T3 cells are susceptible to infection by A-MuLV
via Pit-2 and to infection with E-MuLV via the CAT/y+ amino acid
transporter. However, because of the presence of specific point
mutations in the endogenous murine Pit-1, Pit-1 is not functional as a
GALV receptor in NIH 3T3 cells.
Effect of Viral Infection on PMA-induced Activation of Phosphate
Transport--
Previous studies have established that infection of
cells with retroviruses that selectively recognize either Pit-1 or
Pit-2 resulted in the specific down-modulation of phosphate uptake
mediated by that receptor/transporter (3, 5). A similar phenomenon has
been observed to occur with the E-MuLV CAT/y+ receptor (21, 22). To
examine which of the viral receptor/Pi transporters are
subject to regulation by PMA activation of PKC, studies were carried
out with NIH 3T3 cells infected with different C-type retroviruses. The
results presented in Fig. 1A
demonstrate that infection with A-MuLV decreased short term (2-min)
basal Na/Pi transport (from 900 ± 91 to 404 ± 28 pmol of Pi/min/mg of protein) and, importantly,
completely abolished the activation of Pi transport noted
with exposure of cells to PMA. Infection of cells with E-MuLV would not
be expected to alter Pi uptake, because this virus binds to
a distinct cell surface cationic amino acid transporter (21, 22). Thus,
to control for possible pleiotropic effects of retrovirus infection on
Na/Pi transport, Pi uptake experiments were
carried out with NIH 3T3 cells infected with E-MuLV (Fig.
1B). The results indicated that infection with E-MuLV did
not alter either basal or PMA-induced Na/Pi transport.

View larger version (20K):
[in this window]
[in a new window]
|
Fig. 1.
Effects of infection of cells with the
amphotropic murine leukemia virus, the ecotropic murine leukemia virus,
and the gibbon ape leukemia virus on the activation of
sodiumdependent Pi uptake by PMA. NIH 3T3
cells were productively infected with wild type A-MuLV (A,
) and E-MuLV (B, ) and then treated with 1 µM PMA for the periods indicated. Mink fibroblasts were
infected with wild type A-MuLV (C, ) and wild type GALV-1
(D, ) and then treated with 1 µM PMA for
the times indicated. Uninfected cells were used as control for each
experiment ( ). Pi transport activity was determined as
described under "Experimental Procedures." The data are given as
the mean ± S.E. of two to four separate experiments each carried
out in duplicate.
|
|
As noted, GALV binds to the Pit-1 receptor of mink fibroblasts and
selectively down-modulates Pi uptake caused by Pit-1 (4). To determine whether Na/Pi transport mediated by Pit-1 or
Pit-2 is stimulated by activation of PKC, Pi uptake was
measured in mink cells infected with either A-MuLV or GALV. Infection
of these cells with A-MuLV again completely abolished the activation of Pi transport noted with exposure of cells to PMA (Fig.
1C). Although GALV infection did result in an ~25%
decrease in basal Na/Pi transport, which apparently is
attributable to down-modulation of Pit-1, it did not decrease the
PMA-induced stimulation of Pi uptake noted in these cells
(Fig. 1D). Taken together, these results obtained with
C-type retrovirus-infected cells indicate that Pit-2 is the Pi transporter/viral receptor that is up-regulated with
exposure of cells to PMA.
Effect of Selective PKC Inhibitors on PMA-induced Up-regulation of
Pit-2 Pi Transport--
Although studies have established
a general role for PKC in the regulation of several membrane transport
mechanisms, little is known concerning the functional role(s) of
specific PKC isotypes in these regulatory processes. Thus, studies were
initiated to determine which PKC isotype(s) are involved in mediating
the PMA-induced up-regulation of the Pit-2 transporter/receptor in NIH
3T3 cells. NIH 3T3 cells express a limited, but representative, set of
different PKC isozymes (PKC
, PKC
, PKC
, and PKC
) (18, 23).
Because PMA does not directly activate atypical PKC
, this isotype
would not appear to be involved in the short term PMA-induced
activation of Pit-2 Pi transport. Thus, experiments were
initiated to address which class of PKC isoform stimulates
Pi transport in response to activation by PMA. Two
different PKC inhibitors were used to determine whether the PMA-induced
activation of Na/Pi transport in NIH 3T3 cells was mediated
via a conventional, Ca2+-dependent (PKC
), or
a novel, Ca2+-independent (PKC
and PKC
), isotype.
Addition of the pan-specific bisindolylmaleimide inhibitor, which
inhibits both classical and novel isotypes, resulted in pronounced
inhibition of the PMA-induced activation of Na/Pi uptake
(Fig. 2). Conversely, treatment of the
cells with the Gö 6976 PKC inhibitor, which selectively inhibits only the classical PKC isotypes, did not cause significant inhibition of the PMA-induced up-regulation of Pi transport. These
results suggested that the classical PKC
isoform likely was not
involved in mediating the activation of Na/Pi uptake by
Pit-2 with exposure of NIH 3T3 cells to PMA.

View larger version (15K):
[in this window]
[in a new window]
|
Fig. 2.
Effect of PKC inhibitors on the PMA-induced
stimulation of Pi uptake. Serum-starved NIH 3T3 cells
were preincubated with 0.01% dimethylsulfoxide as solvent control
( ), 500 nM bisindolylmaleimide ( ), or 500 nM Gö 6976 ( ) for 4 h, and then treated with
1 µM PMA for the times indicated. Pi
transport activity was determined as described under "Experimental
Procedures." Data represent the mean ± S.E. of three
independent experiments performed in duplicate (n = 6).
As determined by Student's t test, the inhibitory effects
noted with bisindolylmaleimide were statistically significant
(p < 0.05), whereas the slight effects noted with
Gö 6976 (p > 0.4) were not significant.
|
|
Effect of Overexpression of PKC Isotypes on PMA-induced Stimulation
of Pit-2 Na/Pi Uptake--
To further resolve which of the
PKC isotype(s) may be involved in mediating the PMA activation of the
Na/Pi uptake, we used NIH 3T3 cells overexpressing PKC
,
-
, -
, or -
isozymes to determine the ability of each isotype
to enhance Pit-2 Pi transport activity in the absence of
PMA treatment. The cell cultures were shifted to serum-free media and
incubated in the presence of 20 µM zinc acetate for
24 h to enhance expression of the indicated PKC isotype directed
by the metallothionein promoter of the p
-MTH vector. Overexpression
of PKC
was found to increase Na/Pi uptake, whereas overexpression of PKC
, PKC
, and PKC
did not appreciably alter the level of Pi transport relative to the level determined
in vector control cells (Fig.
3A). Exposure of the PKC
overexpressor cells to 1 µM PMA resulted in only an
additional 15-20% increase in Pi
transport.2 Western blot
analysis showed that the level of expression was similar for each of
the
epitope-tagged PKC isotypes (Fig. 3B). These results
indicate that the selective overexpression of PKC
alone can mimic
the stimulation of Na/Pi uptake observed with PMA treatment
of wild type cells.

View larger version (44K):
[in this window]
[in a new window]
|
Fig. 3.
Effect of overexpression of different PKC
isotypes on the PMA-induced stimulation of Pi uptake.
A, vector control and PKC isotype overexpressor NIH 3T3
cells were serum starved for 24 h in the presence (+) or absence
( ) of 20 µM zinc acetate. Short term (2-min)
sodium-dependent Pi transport activity was
determined in control and overexpressor cells as described under
"Experimental Procedures." Each column represents the mean ± S.E. of three independent experiments performed in duplicate.
B, Western blot analysis of the levels of epitope-tagged
PKC isotypes in total cell extracts of the indicated PKC isotype
overexpressor. NIH 3T3 cells were serum starved for 24 h in the
presence of 20 µM zinc acetate, and total cell extracts
then were prepared. Electrophoresis of total 20-µg protein lysate was
carried out on 4-20% SDS-polyacrylamide gels, and immunoblot analysis
was carried out with anti- epitope tag antibody as described under
"Experimental Procedures."
|
|
Effect of PKC
-specific Antisense Oligonucleotide on PMA-induced
Stimulation of Pit-2 Pi Transport--
To further support
the findings that PKC
is the isotype involved in mediating the
PMA-induced activation of the Pit-2 Pi transporter, studies
were carried out with PKC
-selective antisense oligonucleotide (AON)
to specifically inhibit PKC-
in the cell. As shown in Fig.
4A, pretreatment of NIH 3T3
cells with increasing concentrations of PKC
-AON significantly
decreased the expressed levels of PKC
and had no effect on the
levels of PKC
, PKC
, or PKC
. Densitometric scanning to
quantitate the intensity of the PKC
bands of cells treated with
PKC
-AON relative to AON scrambled controls indicated relative band
densities of 1.0, 0.59, and 0.28 with 0.24, 1.2, and 2.4 mM
oligonucleotide treatment, respectively. Importantly, treatment of the
cells with PKC
-AON did result in inhibition of PMA-induced
up-regulation of Pi transport (Fig. 4B).
Treatment of cells with scrambled oligonucleotides did not have any
effect on either the intracellular level of PKC
or PMA activation of
Na/Pi uptake. Similar experiments with PKC
-AON (ISIS
17254) caused a significant decrease in the levels of PKC
but had no
effect on PMA-induced stimulation of Pi uptake (data not
shown). These data provide additional evidence to support the exclusive
involvement of PKC
in mediating PMA activation of Pit-2.

View larger version (40K):
[in this window]
[in a new window]
|
Fig. 4.
Effect of PKC -specific antisense
oligonucleotide treatment of NIH 3T3 cells on PMA-induced stimulation
of Na/Pi-uptake. The antisense (a) and
scrambled control (c) oligonucleotides at the concentrations
indicated were introduced into NIH 3T3 cells by electroporation, and
the electroporated cells then were incubated for 24 h in the
presence of the introduced oligonucleotides. A, selective
decrease in PKC protein levels with treatment of cells with
PKC -specific antisense oligonucleotides. Cells treated with the
indicated concentrations of PKC -specific antisense (a,
ISIS 17260) or scrambled control (c, ISIS 17261)
oligonucleotides for 24 h were harvested by scraping into lysis
buffer. Aliquots of the cell lysates containing 100 µg of total
protein were analyzed for changes in the levels of specific PKC
isoforms by Western blotting using PKC , - , - , and -
izotype-specific antibodies. Western blot data represent a
characteristic expression pattern of three similar experiments.
B, treatment of NIH 3T3 cells with PKC -specific antisense
oligonucleotides inhibited the PMA-induced increase in Pi
uptake. Cells treated with the indicated concentrations of
oligonucleotides for 24 h were exposed to 0.01% dimethylsulfoxide
(solvent control) or 1 µM PMA for 10 min, and short term
Pi transport activity then was determined as described.
Data are presented as the fold increase in Pi uptake in
response to PMA treatment above basal values determined in the presence
of dimethylsulfoxide. Results are given as the average ± S.E. of
three separate uptake experiments performed in duplicate.
|
|
The suggestion that different PKC isotypes play distinct functional
roles in the cell by phosphorylating either isoform- or subcellular
compartment-specific substrates is widely accepted. However, few
studies have been reported that establish that a specific PKC isotype
may selectively regulate a given biological function. Although a role
for PKC has been implicated in the regulation of numerous membrane
transport mechanisms (10, 24-27), little information is available on
the specific PKC isotype(s) involved in the regulation of these
transport activities. Karim et al. (28) attributed the
modulation of the Na/H antiport to both PKC
and PKC
. PKC
also
has been implicated in the stimulation of anionic amino acid transport
(29), and treatment with antisense oligonucleotides to PKC
has been
shown to block the
1-adrenergic activation of Na-K-2Cl cotransport
(30). The evidence reported here indicates that PKC
is involved in
mediating the PMA-induced up-regulation of Na/Pi uptake by
the Pit-2 transporter/viral receptor.
The Pit-1 and Pit-2 viral receptor/Pi transporters share
56% amino acid identity (31). Hydropathy analysis of Pit-1 and Pit-2
suggested the presence of at least two clusters of putative transmembrane-spanning sequences, along with a large intracellular hydrophilic domain located between the sixth and seventh transmembrane helices (4, 19). There are a number of consensus phosphorylation sites
in both Pit-1 and Pit-2, particularly within the hydrophilic loop
domain. Thus, it is likely that PKC
may directly phosphorylate Pit-2
to stimulate Na/Pi uptake.
However, another mechanism of regulation found with other transporters
is induced redistribution of the transporter from intracellular stores
to the plasma membrane. For example, insulin has been reported to
regulate the intracellular trafficking of glucose transporter 4 (32).
Previously, we have shown that PKC
can regulate Golgi-related functions, including protein trafficking and secretion (17). To address
this possibility, studies were carried out to determine whether PMA
still was able to enhance Pi uptake under conditions in
which vesicle trafficking from the Golgi to the plasma membrane was
blocked by incubating cells at room temperature and by treatment of
cells with nocodazole (to disrupt microtubules) and cytochalasin D (to
disrupt actin filaments). It was found that these treatments did not
block PMA-induced activation of Pi uptake.2
Although these results indicate that PKC
does not act by modulating the trafficking of PiT-2 from the Golgi to the plasma membrane, they do
not fully rule out the possibility that PKC
might act to mediate the
rapid recruitment (fusion) of an existing pool of Pit-2-containing
vesicles to the plasma membrane.
In addition to their role as representative members of an important
family of phosphate transporters, Pit-1 and Pit-2 are of particular
interest as the cell surface receptors for the GALV and A-MuLV
retroviruses, respectively. Many current gene therapy protocols use
GALV- or A-MuLV-enveloped vectors (33, 34). A basic knowledge of murine
leukemia virus receptor regulation and trafficking is likely to be
useful in the development and improvement of gene therapy protocols
based on the use of these retroviral vectors. Although our results
clearly indicate that PKC
is involved in regulating
Na/Pi uptake by Pit-2, it remains to be determined whether
PKC
-mediated regulation of the Pit-2 transporter/viral receptor
might influence recognition of the viral envelope protein and viral
entry into the cell.
 |
ACKNOWLEDGEMENTS |
We thank Dr. Carolyn E. Wilson and Susan Wong
for their help with the reverse transcriptase assays.
 |
FOOTNOTES |
*
The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in
accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
§
Present address: Pain and Neurosensory Mechanisms Branch, NIDR,
National Institutes of Health, Bethesda, MD 20892.

To whom correspondence should be addressed: Laboratory of
Cellular Oncology, NCI, National Institutes of Health, Bldg. 37, Rm.
1E-14, 37 Convent Drive, MSC 4255, Bethesda, MD 20892-4255. Tel.:
301-496-9247; Fax: 301-480-0471; E-mail:
andersow{at}exchange.nih.gov.
2
Z. Jobbagy, M. V. Eiden, and W. B. Anderson, unpublished results.
 |
ABBREVIATIONS |
The abbreviations used are:
Na/Pi, sodium-dependent phosphate;
PKC, protein kinase C;
PMA, phorbol 12-myristate 13-acetate;
DMEM, Dulbecco's modified Eagle's
medium;
A-MuLV, amphotropic murine retrovirus;
E-MuLV, ecotropic MuLV;
GALV, gibbon ape leukemia retrovirus;
AON, antisense
oligonucleotide;
p
-MTH, p
-metallothionein.
 |
REFERENCES |
-
Nishizuka, Y.,
and Nakamura, S.
(1995)
Clin. Exp. Pharmacol. Physiol.
22 Suppl. 1,
S202-S203[Medline]
[Order article via Infotrieve]
-
Olah, Z.,
Lehel, C.,
and Anderson, W. B.
(1993)
Biochim. Biophys. Acta
1176,
333-338[Medline]
[Order article via Infotrieve]
-
Kavanaugh, M. P.,
Miller, D. G.,
Zhang, W.,
Law, W.,
Kozak, S. L.,
Kabat, D.,
and Miller, A. D.
(1994)
Proc. Natl. Acad. Sci. U. S. A.
91,
7071-7075[Abstract]
-
Olah, Z.,
Lehel, C.,
Anderson, W. B.,
Eiden, M. V.,
and Wilson, C. A.
(1994)
J. Biol. Chem.
269,
25426-25431[Abstract/Free Full Text]
-
Wilson, C. A.,
Eiden, M. V.,
Anderson, W. B.,
Lehel, C.,
and Olah, Z.
(1995)
J. Virol.
69,
534-537[Abstract]
-
Murer, H.,
Werner, A.,
Reshkin, S.,
Wuarin, F.,
and Biber, J.
(1991)
Am. J. Physiol.
260,
C885-C899[Abstract/Free Full Text]
-
Arao, M.,
Yamaguchi, T.,
Sugimoto, T.,
Fukase, M.,
and Chihara, K.
(1994)
Eur. J. Endocrinol.
131,
646-651[Medline]
[Order article via Infotrieve]
-
Schmid, C.,
Keller, C.,
Schlapfer, I.,
Veldman, C.,
and Zapf, J.
(1998)
Biochem. Biophys. Res. Commun.
245,
220-225[CrossRef][Medline]
[Order article via Infotrieve]
-
Veldman, C. M.,
Schlapfer, I.,
and Schmid, C.
(1997)
Bone
21,
41-47[CrossRef][Medline]
[Order article via Infotrieve]
-
Veldman, C. M.,
Schlapfer, I.,
and Schmid, C.
(1998)
Endocrinology
139,
89-94[Abstract/Free Full Text]
-
Caverzasio, J.,
and Bonjour, J. P.
(1996)
Kidney. Int.
49,
975-980[Medline]
[Order article via Infotrieve]
-
Palmer, G.,
Bonjour, J. P.,
and Caverzasio, J.
(1997)
Endocrinology
138,
5202-5209[Abstract/Free Full Text]
-
Zhen, X.,
Bonjour, J. P.,
and Caverzasio, J.
(1997)
J. Bone Miner. Res.
12,
36-44[Medline]
[Order article via Infotrieve]
-
Quamme, G.,
Biber, J.,
and Murer, H.
(1989)
Am. J. Physiol.
257,
F967-F973[Abstract/Free Full Text]
-
Quamme, G.,
Pelech, S.,
Biber, J.,
and Murer, H.
(1994)
Biochim. Biophys. Acta
1223,
107-116[Medline]
[Order article via Infotrieve]
-
Olah, Z.,
Lehel, C.,
Jakab, G.,
and Anderson, W. B.
(1994)
Anal. Biochem.
221,
94-102[CrossRef][Medline]
[Order article via Infotrieve]
-
Lehel, C.,
Olah, Z.,
Jakab, G.,
and Anderson, W. B.
(1995)
Proc. Natl. Acad. Sci. U. S. A.
92,
1406-1410[Abstract]
-
Lehel, C.,
Olah, Z.,
Mischak, H.,
Mushinski, J. F.,
and Anderson, W. B.
(1994)
J. Biol. Chem.
269,
4761-4766[Abstract/Free Full Text]
-
Wilson, C. A.,
and Eiden, M. V.
(1991)
J. Virol.
65,
5975-5982[Medline]
[Order article via Infotrieve]
-
Weiss, R. A.,
and Tailor, C. S.
(1995)
Cell
82,
531-533[Medline]
[Order article via Infotrieve]
-
Wang, H.,
Kavanaugh, M. P.,
North, R. A.,
and Kabat, D.
(1991)
Nature
352,
729-731[CrossRef][Medline]
[Order article via Infotrieve]
-
Wang, H.,
Dechant, E.,
Kavanaugh, M.,
North, R. A.,
and Kabat, D.
(1992)
J. Biol. Chem.
267,
23617-23624[Abstract/Free Full Text]
-
Mischak, H.,
Goodnight, J.,
Kolch, W.,
Martiny-Baron, G.,
Schaechtle, C.,
Kazanietz, M. G.,
Blumberg, P. M.,
Pierce, J. H.,
and Mushinski, J. F.
(1993)
J. Biol. Chem.
268,
6090-6096[Abstract/Free Full Text]
-
Ribeiro, C. M. P.,
and Putney, J. W., Jr.
(1996)
J. Biol. Chem.
271,
21522-21528[Abstract/Free Full Text]
-
Corey, J. L.,
Davidson, N.,
Lester, H. A.,
Brecha, N.,
and Quick, M. W.
(1994)
J. Biol. Chem.
269,
14759-14767[Abstract/Free Full Text]
-
Enyedi, A.,
Verma, A. K.,
Filoteo, A. G.,
and Penniston, J. T.
(1996)
J. Biol. Chem.
271,
32461-32467[Abstract/Free Full Text]
-
Rokaw, M. D.,
West, M.,
and Johnson, J. P.
(1996)
J. Biol. Chem.
271,
32468-32473[Abstract/Free Full Text]
-
Karim, Z.,
Defontaine, N.,
Paillard, M.,
and Poggioli, J.
(1995)
Am. J. Physiol.
269,
C134-C140[Abstract/Free Full Text]
-
Franchi-Gazzola, R.,
Visigalli, R.,
Bussolati, O.,
and Gazzola, G. C.
(1996)
J. Biol. Chem.
271,
26124-26130[Abstract/Free Full Text]
-
Liedtke, C. M.,
and Cole, T.
(1997)
Am. J. Physiol.
273,
C1632-C1640[Abstract/Free Full Text]
-
van Zeijl, M.,
Johann, S. V.,
Closs, E.,
Cunningham, J.,
Eddy, R.,
Shows, T. B.,
and O'Hara, B.
(1994)
Proc. Natl. Acad. Sci. U. S. A.
91,
1168-1172[Abstract]
-
Hudson, A. W.,
Ruiz, M.,
and Birnbaum, M. J.
(1992)
J. Cell Biol.
116,
785-797[Abstract]
-
Barquinero, J.,
Kiem, H. P.,
von Kalle, C.,
Darovsky, B.,
Goehle, S.,
Graham, T.,
Seidel, K.,
Storb, R.,
and Schuening, F. G.
(1995)
Blood
85,
1195-1201[Abstract/Free Full Text]
-
Kavanaugh, M. P.,
and Kabat, D.
(1996)
Kidney Int.
49,
959-963[Medline]
[Order article via Infotrieve]
Copyright © 1999 by The American Society for Biochemistry and Molecular Biology, Inc.