A Selective Peroxisome Proliferator-Activated Receptor-
(PPAR
) Modulator Blocks Adipocyte Differentiation but Stimulates Glucose Uptake in 3T3-L1 Adipocytes
Ranjan Mukherjee1,
Patricia A. Hoener,
Lily Jow,
James Bilakovics,
Kay Klausing,
Dale E. Mais,
Amy Faulkner,
Glenn E. Croston2 and
James R. Paterniti Jr.
Departments of Pharmacology (R.M., P.A.H., L.J., J.B., J.R.P.),
Endocrine Research (D.E.M.), Medicinal Chemistry (A.F.), Retinoid
Research (K.K.), and New Leads Discovery (G.E.C.) Ligand Pharmaceuticals, Inc. San Diego, California 92121
 |
ABSTRACT
|
---|
Peroxisome proliferator-activated
receptor-
(PPAR
) agonists such as the thiazolidinediones are
insulin sensitizers used in the treatment of type 2 diabetes. These
compounds induce adipogenesis in cell culture models and increase
weight gain in rodents and humans. We have identified a novel PPAR
ligand, LG100641, that does not activate PPAR
but selectively and
competitively blocks thiazolidinedione-induced PPAR
activation and
adipocyte conversion. It also antagonizes target gene activation as
well as repression in agonist-treated 3T3-L1 adipocytes. This
novel PPAR
antagonist does not block adipocyte differentiation
induced by a ligand for the retinoid X receptor (RXR), the
heterodimeric partner for PPAR
, or by a differentiation
cocktail containing insulin, dexamethasone, and
1-methyl-3-isobutylxanthine. Surprisingly, LG100641, like the
PPAR
agonist rosiglitazone, increases glucose uptake in
3T3-L1 adipocytes. Such selective PPAR
antagonists may help
determine whether insulin sensitization by thiazolidinediones is
mediated solely through PPAR
activation, and whether there are
PPAR
-ligand-independent pathways for adipocyte differentiation. If
selective PPAR
modulators block adipogenesis in vivo,
they may prevent obesity, lower insulin resistance, and delay the onset
of type 2 diabetes.
 |
INTRODUCTION
|
---|
Peroxisome proliferator-activated receptor-
(PPAR
)
is a member of the intracellular receptor family of transcription
factors (1). PPAR
is expressed at high levels in fat, spleen, and
colon but is also detectable in skeletal muscle, liver, and in other
tissues (1, 2). Interest in this receptor increased when it was clear
that insulin sensitizers of the thiazolidinedione class
[troglitazone, rosiglitazone (BRL 49653),
Pioglitazone], are high-affinity ligands for
PPAR
(3). A correlation was reported between the affinity of
thiazolidinediones for PPAR
and the minimum effective dose required
to lower glucose levels in diabetic rodent models (4). It was therefore
proposed that the antidiabetic activity of these compounds reflects
their ability to bind and activate PPAR
. However, antidiabetic
actions of thiazolidinediones may also be partly independent of
PPAR
.
Preadipocyte cell lines such as 3T3-L1 differentiate into adipocytes
after treatment with dexamethasone, insulin, and
1-methyl-3-isobutylxanthine (IBMX) (5, 6). Ectopic expression and
ligand activation of PPAR
also induces differentiation of
preadipocytes to adipocytes (7). PPAR
may therefore play a key role
in adipogenesis.
To understand better the role of PPAR
in adipogenesis, we
identified a compound, LG100641, that binds to PPAR
but does not
activate gene expression. This ligand displaces thiazolidinediones from
the receptor, thereby blocking its transcriptional activity.
We report here that LG100641 is a novel, PPAR
-specific antagonist
that blocks thiazolidinedioneinduced adipocyte differentiation but
stimulates insulin-mediated glucose uptake in adipocytes. It also
antagonizes target gene activation as well as repression in
agonist-treated 3T3-L1 adipocytes. Surprisingly, it does not block
differentiation induced by retinoid X receptor (RXR)-selective agonists
or by the combination of dexamethasone, insulin, and IBMX. Such a
selective antagonist will be a valuable tool to determine whether
PPAR
activation is necessary for inducing adipogenesis and for
elucidating the mechanism of insulin sensitization by
thiazolidinediones. Compounds of this class could determine whether
blocking PPAR
activity in vivo gives rise to animals with
less adipose tissue and increased insulin sensitivity. If that is the
case, then PPAR
ligands with activities very different from the
thiazolidinediones may be useful in the treatment of obesity, insulin
resistance, and type 2 diabetes.
 |
RESULTS
|
---|
We have identified a novel PPAR
ligand LG100641 (Fig. 1A
) that displaces
[3H]rosiglitazone from PPAR
with an
inhibition constant (Ki )
of 435 nM (Fig. 1B
). While the
affinity is less than that of rosiglitazone (3), it is higher
than that of troglitazone (8). Structurally, LG100641 is
very different from thiazolidinediones but similar to RXR selective
ligands or rexinoids (9, 10). However, LG100641 shows very weak binding
to RXRs (Ki of 25 µM for RXR
,
Fig. 1C
) and no detectable binding to RARs (Ki >
30 µM, data not shown).
In a cotransfection assay, LG100641 does not activate PPAR
(Fig. 2A
) whereas the PPAR
ligand and
agonist, rosiglitazone, shows significant activity. Since LG100641
binds to PPAR
but does not transactivate, we next determined whether
it antagonizes ligand-induced PPAR
activation. Indeed,
dose-dependent antagonism of rosiglitazone-induced activation of
PPAR
was observed (Fig. 2A
). LG100641 is a PPAR
-specific
antagonist since it does not antagonize activation of PPAR
by
GW2331, a PPAR
ligand and agonist (11) (Fig. 2B
) or that of RXR
by LG100268 (9, 10) (Fig. 2C
). It did not activate the glucocorticoid
receptor or PPARß (
) (data not shown). Hence, LG100641 is a
PPAR
ligand that is transcriptionally neutral and competitively
antagonizes activation of PPAR
by thiazolidinediones.
Ligand activation of nuclear receptors depends upon recruitment of
coactivators (12). One such coactivator, the steroid receptor
coactivator-1 (SRC-1), is recruited to rosiglitazone-bound PPAR
(13). Unlike rosiglitazone, LG100641-bound PPAR
does not recruit
SRC-1 (Fig. 3
). When present in molar
excess, LG100641 prevents rosiglitazone from binding to PPAR
and
recruiting SRC-1. Hence, a possible mechanism of LG100641 antagonism is
by preventing SRC-1 recruitment by a PPAR
agonist.
PPAR
is a key transcriptional factor controlling adipocyte
differentiation. Overexpression of PPAR
in nonadipogenic cell lines
(e.g. fibroblasts) and transcriptional activation by a
PPAR
agonist is sufficient to induce the adipocyte phenotype (7).
Indeed, induction of adipogenesis is a well documented response of
PPAR
agonists both in vitro (3) and in vivo
(14). Since LG100641 antagonizes the effect of rosiglitazone in
cotransfection assays, we next determined whether it blocks
thiazolidinedione-induced differentiation of 3T3-L1 cells. Figure 4A
demonstrates induction of adipocyte
differentiation by rosiglitazone as shown by an increase in
triglyceride content. LG100641 does not increase triglyceride levels,
which is consistent with the cotransfection data. It results in a
dose-dependent decrease in triglyceride accumulation when added
together with rosiglitazone. A similar result was obtained by Oil Red O
staining (see illustration on cover and data not shown). We conclude
LG100641 antagonizes adipocyte differentiation induced by
thiazolidinedione. LG100641 does not, however, block adipocyte
differentiation induced by dexamethasone, insulin, and IBMX (Fig. 4B
).

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Figure 4. LG100641 Blocks Thiazolidinedione-Induced 3T3-L1
Cell Differentiation (A) but not Differentiation Induced with
Dexamethasone, Insulin, and IBMX (B) or the RXR Ligand LG100268 (C)
3T3-L1 cells were induced to differentiate with rosiglitazone
(BRL 49653), LG100641, LG100268, dexamethasone, insulin,
and IBMX or combinations of inducer and antagonist at the
concentrations shown. Triglyceride quantification was performed after 7
days of differentiation. Data are the mean ±
SEM. Statistically significant differences in the
rosiglitazone plus LG100641- treated cells compared with cells treated
with rosiglitazone alone were determined by Students t
test.
|
|
RXR agonists also induce adipogenesis (15). However, LG100641 does not
block LG100268-induced adipogenesis (Fig. 4C
). LG100641 does not
displace LG100268 from RXR and is therefore unable to antagonize
LG100268-induced differentiation. We have previously shown that an RXR
antagonist (LG100754) does not antagonize PPAR
activation by
rosiglitazone (16). Here we demonstrate the converse: that a PPAR
antagonist does not antagonize a biological pathway driven by RXR
ligands via PPAR
/RXR. This result also demonstrates the selectivity
of LG100641 action for PPAR
. This is surprising and indicates that
adipocyte differentiation may occur via pathways that do not require
PPAR
activation.
LG100641 also blocks PPAR
-induced 3T3-L1 adipocyte differentiation
as measured by expression of aP2, an adipocyte-specific marker gene.
The aP2 mRNA is highly expressed in 3T3-L1 cells treated with
rosiglitazone, but the induction is severely blocked when LG100641 is
added together with rosiglitazone (Fig. 5A
). LG100641 alone does not induce aP2
gene expression.

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Figure 5. LG100641 Blocks Thiazolidinedione-Induced Gene
Expression
A, LG100641 blocks rosiglitazone-mediated aP2 mRNA induction during
adipocyte differentiation. Northern blot analysis was performed with
RNA from 3T3-L1 cells induced to differentiate with DMSO (vehicle), 1
µM rosiglitazone (BRL), 30 µM
LG100641 (LG641), or the combination of rosiglitazone and LG100641 (1
µM and 30 µM), respectively. RNA
was harvested from cells after 7 days of differentiation. B, LG100641
antagonizes rosiglitazone-induced gene expression in 3T3-L1 adipocytes.
3T3-L1 cells were fully differentiated into adipocytes with
dexamethasone, insulin, and IBMX. After 7 days of differentiation,
ligands were added for 3 more days. RNA was harvested and analyzed by
Northern blot analysis. Ligand concentrations were the same as in panel
A.
|
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To determine whether LG100641 antagonizes induction of PPAR
target
genes in fully differentiated adipocytes, 3T3-L1 adipocytes were
treated for 3 days with rosiglitazone in the presence or absence of
LG100641 and RNA levels of aP2 and adipsin, two known target genes for
PPAR
measured by Northern blot analysis (Fig. 5B
). Induction of aP2
RNA was observed in the presence of rosiglitazone. This induction was
abolished in the presence of the antagonist. Surprisingly,
rosiglitazone decreased adipsin RNA levels, and this repression was
attenuated in the presence of the antagonist. LG100641 by itself did
not have an appreciable effect on the expression of these two genes.
However, in adipocytes, it antagonized modulation of these two target
genes by the PPAR
agonist rosiglitazone. To the best of our
knowledge, this is the first demonstration of antagonism of
thiazolidinedione-induced target gene modulation in mature
adipocytes.
These results together demonstrate that LG100641 1) prevents
rosiglitazone-induced coactivator recruitment and transactivation of
PPAR
, 2) blocks conversion of preadipocytes to adipocytes by
rosiglitazone, and 3) antagonizes thiazolidinedione-induced target gene
expression in adipocytes. Therefore, LG100641 is an antagonist for
PPAR
.
PPAR
agonists (thiazolidenediones) are insulin sensitizers (17);
they decrease hyperglycemia and hyperinsulinemia and improve insulin
sensitivity in peripheral tissues in vivo (18). The
mechanism by which thiazolidinediones improve insulin sensitivity is
not known. Insulin-stimulated glucose uptake in 3T3-L1 adipocytes is a
well established assay in cell culture and a relevant measure of
insulin action in peripheral tissues. PPAR
agonists increase glucose
uptake in 3T3-L1 adipocytes (19). Since LG100641 is a PPAR
antagonist, we tested its effect on the magnitude of glucose uptake in
3T3-L1 adipocytes.
In this assay, rosiglitazone increases 2-deoxyglucose uptake (Fig. 6A
) in agreement with results reported
for other thiazolidinediones (19). Tumor necrosis factor-
(TNF
), a cytokine that induces insulin resistance in 3T3-L1
adipocytes (20) and in vivo (21), decreases
insulin-stimulated glucose uptake in these cells. This result
demonstrates that the assay identifies compounds that stimulate insulin
sensitivity, e.g. rosiglitazone, as well as those that
induce insulin resistance, e.g. TNF
. However, LG100641,
even at the highest dose of 30 µM, does not
decrease basal or insulin-stimulated glucose uptake. In fact, there is
a small but significant increase in glucose uptake at the higher
concentrations. Therefore, at a concentration that clearly blocks
adipocyte differentiation (Fig. 4A
), LG100641 does not decrease glucose
uptake in 3T3-L1 adipocytes. Hence, LG100641 is a selective modulator
of PPAR
activity. When both ligands were added together, LG100641
attenuates the high response induced by rosiglitazone consistent with
its ability to displace rosiglitazone from PPAR
(Fig. 6B
).

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Figure 6. LG100641 Increases 2-Deoxyglucose Uptake in 3T3-L1
Adipocytes
A. 3T3-L1 adipocytes were treated with vehicle (control), rosiglitazone
(BRL 49653), LG100641, and TNF at the concentrations
indicated for 3 days, and [3H]2-deoxyglucose uptake assay
was performed as described in Materials and Methods.
Data are the mean ± SEM. Statistically
significant differences compared with the vehicle-treated cells were
determined by Students t test and are indicated.
LG100641 antagonizes rosiglitazone-induced stimulation of
2-deoxyglucose uptake in 3T3-L1 adipocytes (B). The assay was performed
as above with the indicated concentrations of ligands. Statistically
significant decreases in LG100641-treated samples compared with
BRL 49653 treatment alone are indicated.
|
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 |
DISCUSSION
|
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We report the identification of a PPAR
antagonist,
LG100641, a novel PPAR
ligand structurally different from the
thiazolidinediones but related to a certain rexinoid selective
structure, LG100268. Surprisingly, it binds very poorly to RXRs but has
a greater affinity for PPAR
than troglitazone. In
binding assays carried out against all three RXR subtypes up to a
concentration of 30 µM, LG100641 failed to achieve a 50%
inhibition of [3H]-9-cis-RA, (Fig. 1C
and data not shown). However, extrapolating to obtain an
IC50 value allowed approximate
Ki values to be obtained in the 1525
µM range for the three RXR subtypes. Unlike the
thiazolidinediones, it does not transactivate PPAR
but, instead,
acts as an antagonist. LG100641 may induce a conformational change in
PPAR
different from that of an agonist, resulting in failure to
recruit a coactivator (e.g. SRC-1, Fig. 3
). Hence,
LG100641-bound PPAR
is transcriptionally silent.
LG100641 blocks rosiglitazone-induced 3T3-L1 cell differentiation (Fig. 4A
) but not adipocyte differentiation induced by dexamethasone,
insulin, and IBMX. This suggests that there may be at least two
pathways for 3T3-L1 adipocyte differentiation. One is regulated by
PPAR
and its ligand and is blocked by a PPAR
antagonist. The
second pathway is independent of PPAR
ligand activation and
therefore cannot be blocked by the PPAR
antagonist. Differentiation
by insulin, dexamethasone, and IBMX acting through the second pathway
may involve activation of genes like C/EBP
(22). Hence, a PPAR
antagonist is a useful tool to dissect the process of adipogenesis.
LG100641 does not block RXR agonist-induced adipogenesis. In
transactivation, the transcriptional response of an agonist to one
partner of the PPAR/RXR heterodimer is enhanced by an agonist bound to
the other partner (9, 16). However, a competitive antagonist bound to
one partner does not antagonize the transcriptional response from an
agonist bound to the other. This is true for both RXR antagonists
(e.g. LG100754) (16) and PPAR
antagonists
(e.g. LG100641). It is also possible that a different class
of antagonists, when bound to PPAR, induces a conformational change in
the PPAR/RXR heterodimer such that it disrupts binding of the RXR
ligand and vice versa. Such ligands would antagonize
transactivation from either side of the heterodimer.
LG100641 inhibits thiazolidinedione-induced conversion of preadipocytes
to adipocytes. In adipocytes it antagonized the ability of
rosiglitazone to induce aP2 expression. We show that although
rosiglitazone induced adipsin expression during adipocyte
differentiation (23), it unexpectedly repressed adipsin gene expression
in mature adipocytes. LG100641 blocked agonist-mediated repression of
adipsin. Thus, in mature adipocytes it also acts as a PPAR
antagonist effectively attenuating agonist-mediated transactivation and
transrepression of target genes.
Such an antagonist might be expected to decrease glucose uptake.
However, it did not inhibit basal and insulin-mediated glucose disposal
in adipocytes. In fact, LG100641 at high concentrations acts as a weak
agonist in glucose uptake assays. Identification of such selective
PPAR
modulators that block adipocyte differentiation but increase
glucose uptake offer the potential for improved therapy for metabolic
diseases. A partial PPAR
agonist (GW0072) that inhibits adipocyte
differentiation has been recently described (23). LG100641 is
structurally different from GW0072, and in contrast to GW0072, LG100641
in the cotransfection assays described shows no agonism of PPAR
.
Heterozygous PPAR
knockout mice show increased insulin sensitivity
in response to a high-fat diet compared with wild-type animals (24).
This suggests that in some cases (e.g. obesity)
down-regulating PPAR
activity may increase insulin sensitivity.
Since PPAR
activation is crucial for adipogenesis, PPAR
antagonists may be useful in the treatment of obesity. Obese
individuals have an increased body fat content above a normal standard
range. They often have elevated levels of FFA, which are recognized
PPAR ligands. 15-Deoxy-
12,14-PGJ2, is a naturally
occurring ligand and agonist for PPAR
(25, 26). Treatment with
current PPAR
agonists, the thiazolidinediones, leads to
increased adiposity and body weight gain in rodents (14) and weight
gain in human patients (27, 28). Our data suggest that compounds such
as LG100641 could prevent adipogenesis, insulin resistance, and obesity
by blocking endogenous ligand-induced activation of PPAR
and the
consequent differentiation of preadipocytes into adipocytes. In
addition, these compounds may increase glucose disposal in peripheral
tissues.
Controlling obesity in rhesus monkeys prevents the onset of diabetes
mellitus (29). In addition, an abundant literature documents that
weight loss in type 2 diabetic humans improves insulin sensitivity. An
effective antiobesity agent may lower insulin resistance and prevent or
significantly delay the onset of type 2 diabetes. Our data suggest that
such selective PPAR
modulators might prevent obesity without
inducing insulin resistance in peripheral tissues. In vivo
studies are necessary to further explore this hypothesis.
 |
MATERIALS AND METHODS
|
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Reagents
2-[(5,5,8,8-Tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)
carbonyl]benzoic acid (LG100641), GW2331(3), rosiglitazone (BRL
49653), and LG100268 were synthesized at Ligand Pharmaceuticals, Inc. (San Diego, CA). Stock solutions were made
by dissolving the compounds in dimethylsulfoxide (DMSO). TNF
and
insulin were purchased from Genzyme Corp. and
Sigma (St. Louis, MO), respectively.
Ligand Binding Assay
Binding affinities of LG100641 to recombinant
baculovirus-expressed hPPAR
1 and hRXR were determined using
[3H] rosiglitazone and
[3H] 9-cis-retinoic acid as the
radioligand, respectively (30). The Ki values
were calculated by measuring IC50 values and the
application of Cheng-Prusoff equation (31).
Transfection Assays
Cotransfection assays were performed in CV-1 cells (9) using
expression vectors for hPPAR
1 (16), hPPAR
(32), and hRXR
(33)
and the PPRE-tk-LUC reporter (34).
PPAR-SRC-1 Immunopulldown Assays
In vitro translated, labeled SRC-1 (12), and 5 µg
recombinant baculovirus-expressed hPPAR
1 protein extract were
incubated with ligand in IP buffer (10 mM HEPES,
pH 7.8, 50 mM KCl, 1 mM
DTT, 2.5 mM MgCl2, 20%
glycerol, and 0.1% NP40) for 1 h at 4 C. Twenty microliters of
protein A Sepharose (Pharmacia Biotech, Piscataway, NJ)
stock made by adding 1.5 g powder in 16 ml IP buffer, and 2 µl
of PPAR
polyclonal antibody were added in 100 µl of IP buffer,
rotated for 1 h at 4 C and centrifuged for 6 min at 14,000 rpm in
an Eppendorf 5415C microcentrifuge. The beads were washed
three times with cold IP buffer and boiled in Laemmli buffer, and the
supernatant was electrophoresed on 10% TrisGlycine gels
(Novex, San Diego, CA). The bands were visualized by
autoradiography using the Amplify detection system (Pharmacia Biotech, Piscataway, NJ).
3T3-L1 Cell Culture and Differentiation Assays
3T3-L1 cells (American Type Culture Collection,
Manassas, VA) were grown in DMEM supplemented with 10%
heat-inactivated calf serum. Two days after reaching confluence,
differentiation was induced in DMEM supplemented with 10% FCS
(HyClone Laboratories, Inc., Logan, UT), insulin (10
µg/ml, Sigma, St. Louis, MO) and PPAR
or RXR ligands.
After 3 days the medium was replaced by DMEM supplemented with 10%
FCS, insulin, and PPAR
or RXR ligands. Two days later the cells were
refed with DMEM plus FCS only. After 7 days of differentiation, cells
were harvested for RNA and triglyceride analysis, or stained by Oil Red
O, an indicator of cell lipid content.
Alternatively, cells were induced to differentiate with the combination
of dexamethasone, insulin and IBMX (35) with or without PPAR
ligand
present during the first 5 days of differentiation. Cells were
harvested for triglyceride analysis after 7 days of
differentiation.
Triglyceride Assay
Treated 3T3-L1 adipocytes were washed gently with PBS and lysed
with PBS supplemented with 0.1% NP40. Triglyceride content was
measured using the Triglyceride GPO-Trinder kit (Sigma).
The absorbance was measured at 540 nm, and triglyceride was normalized
to protein content determined by the Bradford assay.
[3H]-2-deoxy-D-Glucose Uptake
Assay in Differentiated 3T3-L1 Adipocytes
3T3-L1 cells were grown in 12-well tissue culture plates
(Corning, Inc. Costar, Corning, NY) and differentiated
into adipocytes with dexamethasone, insulin, and IBMX (35). Seven days
after induction of differentiation, test compounds were added for an
additional 3 days. After two rinses with serum-free DMEM, cells were
incubated for 3 h in serum-free DMEM and rinsed at room
temperature four times with freshly prepared KRPH buffer (5
mM phosphate, pH 7.4
(NaH2PO4-H2O
+
Na2HPO4-7H2O),
20 mM HEPES pH 7.4, 1 mM
MgSO4, 1 mM
CaCl2, 136 mM NaCl, 4.7
mM KCl). The buffer was removed and the cells were
incubated with or without 100 nM insulin in KRPH buffer at
37 C for 20 min. The buffer was replaced with 1 µCi/well of
[3H]-2-deoxy-D-glucose (NEN Life Science Products; Boston, MA) in KRPH buffer supplemented
with 100 µM 2-deoxy-D-glucose
(Aldrich, Milwaukee, WI) with incubation for 10 min at
room temperature. The supernatant was removed, and plates were rinsed
carefully four times with cold PBS. Plates were drained briefly and
cells lysed overnight in 0.5 ml/well 0.1 N NaOH. Four
hundred microliters of lysate were added to a scintillation vial,
neutralized with 40 µl of 1 N HCl, and 4 ml of Ecoscint A
scintillation fluid (National Diagnostics; Atlanta, GA) were added. The
vials were mixed and counted.
Northern Blot Analysis
3T3-L1 adipocyte RNA (10 µg per lane) was loaded onto a 1%
agarose-formaldehyde gel. Northern blotting was done by standard
procedures with cDNA fragments labeled by random priming. The bands
were visualized by autoradiography. To control for loading, the blots
were stripped and hybridized with pTRI RNA 28S riboprobe (Ambion, Inc. Austin, TX).
 |
ACKNOWLEDGMENTS
|
---|
We gratefully acknowledge the help of Kathy Ogilvie, Marcus
Boehm, Luc Farmer, and members of New Leads Discovery. We also thank
Drs. Bruce Spiegelman for aP2 and adipsin and Ming-Jer-Tsai for the
SRC-1 cDNA.
 |
FOOTNOTES
|
---|
Address requests for reprints to: James R. Paterniti, Jr. Ligand Pharmaceuticals, Inc., 10275 Science Center Drive, San Diego, California 92121 or Ranjan Mukherjee, DuPont Pharmaceuticals Co., Experimental Station, E400, Wilmington, DE 19880.
Ranjan Mukherjee and James R. Paterniti are joint corresponding
authors.
1 Present address: Dupont Pharmaceuticals Company, Experimental
Station, E/400, Wilmington, DE 19880-0400. 
2 Present address: Acadia Pharmaceuticals, 3911 Sorrento Valley
Boulevard, San Diego, California 92121-1402. 
{hd2}Note Added in Proof
{smtexf}While this manuscript was in preparation, Wright
et al., identified a synthetic antagonist for PPAR
, BADGE
with a Kd(app) of 100 µM (H. M. Wright, C. B. Clish, T.
Mikami, S. Hauser, K. Yanagi, R. Hiramatsu, C. N. Serhan, B. M.
Spiegelman, J Biol Chem 275:18731877, 2000). This compound inhibited
adipogenesis, but its effect on glucose uptake was not shown.
Received for publication March 1, 2000.
Revision received June 1, 2000.
Accepted for publication June 8, 2000.
 |
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