From the Department of Medicine, Diabetes Research Center, Albert
Einstein College of Medicine, Bronx, New York 10461, the
Division of Gene Therapy Science, Osaka University School
of Medicine, Suita, 505 0871 Japan, and the § Department of
Biochemistry and Molecular Biology I, School of Biology, Complutense
University, Madrid, 28040 Spain
Received for publication, August 14, 2000, and in revised form, May 2, 2001
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ABSTRACT |
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Leptin, a circulating hormone
secreted mainly from adipose tissues, is involved in the control of
body weight. The plasma concentrations are correlated with body
mass index, and are reported to be high in patients with insulin
resistance, which is one of the major risk factors for cardiovascular
disease. However, the direct effect of leptin on vascular wall cells is
not fully understood. In this study, we investigated the effects of
leptin on reactive oxygen species (ROS) generation and expression of
monocyte chemoattractant protein-1 (MCP-1) in bovine aortic endothelial
cells (BAEC). We found that leptin increases ROS generation in BAEC in
a dose-dependent manner and that its effects are additive
with those of glucose. Rotenone, thenoyltrifluoroacetone (TTFA),
carbonyl cyanide m-chlorophenylhydrazone (CCCP), Mn(III)tetrakis
(4-benzoic acid) porphyrin (MnTBAP), uncoupling protein-1 (UCP1)
HVJ-liposomes, or manganese superoxide dismutase (MnSOD) HVJ-liposomes
completely prevented the effect of leptin, suggesting that ROS arise
from mitochondrial electron transport. Leptin increased fatty acid
oxidation by stimulating the activity of carnitine
palmitoyltransferase-1 (CPT-1) and inhibiting that of acetyl-CoA
carboxylase (ACC), pace-setting enzymes for fatty acid oxidation and
synthesis, respectively. Leptin-induced ROS generation, CPT-1
activation, ACC inhibition, and MCP-1 overproduction were found to be
completely prevented by either genistein, a tyrosine kinase inhibitor,
H-89, a protein kinase A (PKA) inhibitor, or tetradecylglycidate, a
CPT-1 inhibitor. Leptin activated PKA, and the effects of leptin were
inhibited by the cAMP antagonist Rp-cAMPS. These results suggest
that leptin induces ROS generation by increasing fatty acid oxidation
via PKA activation, which may play an important role in the progression
of atherosclerosis in insulin-resistant obese diabetic patients.
Leptin, a circulating hormone secreted mainly by adipose
tissues, is involved in the control of body weight through the effects on food intake and energy expenditure (1, 2). In humans, the
plasma concentrations of leptin are markedly correlated with body mass
index and are also reported to be higher in insulin-resistant first-degree relatives of patients with
non-insulin-dependent diabetes mellitus
(NIDDM)1 and type I diabetes
compared with normal individuals (3-5). Disorders associated with
hyperleptinemia such as obesity and insulin resistance are major risk
factors for cardiovascular diseases (6, 7). Recently, the leptin
receptor has been identified on endothelial cells, and leptin has been
shown to promote both angiogenesis and inflammation (8, 9). However,
the mechanism by which leptin induces inflammation remains to be elucidated.
Adipocytes have recently been shown to secrete pro-inflammatory
cytokines such as tumor necrosis factor- Cell Culture Conditions--
Confluent BAEC cells (passage
4-10) were maintained in Eagle's minimal essential medium (Life
Technologies, Inc., Grand Island, NY) containing 0.4% fetal bovine
serum, essential and nonessential amino acids and antibiotics. Cells
were incubated with various concentrations of human recombinant leptin
plus either 5 mM glucose, 10 mM glucose, 30 mM glucose, 5 mM glucose plus 5 µM rotenone, 10 µM thenoyltrifluoroacetone
(TTFA), 0.5 µM carbonyl cyanide m-chlorophenylhydrazone
(CCCP), 100 µM Mn(III)tetrakis (4-benzoic acid) porphyrin
(MnTBAP), uncoupling protein-1 (UCP1) HVJ-liposomes, manganese
superoxide dismutase (MnSOD) HVJ-liposomes, 50 µM
genistein, 10 µM H-89 dihydrochloride, 25 µM Rp-cAMPS, or 20 µM tetradecylglycidate (TDGA),2 as indicated.
Leptin, rotenone, TTFA, CCCP, digitonin, palmitoyl-CoA, and butyryl-CoA
were purchased from Sigma Chemical Co. MnTBAP, genistein, and H-89
dihydrochloride were purchased from Calbiochem (La Jolla, CA).
2-deoxy-D-[1-3H]glucose,
[1-14C]palmitic acid,
L-[methyl-3H]carnitine, and
[1-14C]acetyl-CoA were purchased from Amersham Pharmacia
Biotech (Buckinghamshire, UK). 5 µl of each HVJ-liposome was added
for experiments in 96-well plates (80,000 cells). Cells were washed
after 2-h incubation. Transfection efficiency was >90% as assessed by
FACS analysis of eGFP expression. Reagents alone had no effect on the
variables measured in Figs. 1, 4, 5, 6, and 7 (data not shown).
Intracellular ROS--
The intracellular formation of ROS was
detected by using the fluorescent probe CM-H2DCFDA
(Molecular Probes Inc., Eugene, OR). Cells (1 × 105/ml) were loaded with 10 µM
CM-H2DCFDA, incubated for 60 min at 37 °C, and analyzed
in an HTS 7000 Bio Assay Fluorescent Plate Reader (PerkinElmer Life
Sciences) using the HTSoft program. ROS production was determined from
an H2O2 standard curve (10-200 µM).
2-Deoxy-D-Glucose (2-DG) Uptake--
Cells were
incubated with 10 ng/ml leptin for 45 min in medium containing 5 mM glucose. Then cells were washed five times with
phosphate-buffered saline (PBS) and incubated with 1 ml of PBS
containing 1 µCi 2-deoxy-D-[1-3H]glucose
for 5 min. Cells were solubilized in 1 ml of 1 N NaOH for 60 min at
37 °C, and the radioactivity was counted as described previously
(17).
Glucose Flux through Glycolysis--
Cells were incubated with
10 ng/ml leptin for 45 min in medium containing 5 mM
glucose. 10 µCi/ml of 5-3H was added, and the conversion
to [3H]H2O was quantitated as described
previously (15).
Glucose Flux through the Tricarboxylic Acid (TCA)
Cycle--
Cells were incubated with 10 ng/ml leptin for 45 min in
medium containing 5 mM glucose. 1 µCi/ml of
U-14C glucose was added, and the conversion to
[14C]CO2 was quantitated as described
previously (15).
Fatty Acid Oxidation--
Cells were prelabeled overnight in
medium containing 50 µM [1-14C]palmitic
acid. After trypsinization, cells were incubated with 10 ng/ml leptin
for 2 h in medium containing 5 mM or 30 mM
glucose. The conversion to [14C]CO2 was
quantitated as described previously (18).
Epstein-Barr Virus Replicon Vectors--
Rat UCP1 sense
and antisense cDNAs were generously provided by Dr. Daniel Riquier,
Center National de la Recherche Scientifique-Unite Propre 1511, Meudon,
France. Human MnSOD cDNA was generously provided by Dr. Larry
Oberley, University of Iowa College of Medicine, Iowa City, IA. These
cDNAs were cloned into the Epstein-Barr virus replicon-based
plasmid pEB (19) and used to prepare HVJ-liposomes.
Preparation of HVJ-Liposomes--
Cationic HVJ-liposomes were
prepared as described previously (19), using 9.75 mg of the dried
lipids and 200 µg of plasmid DNA.
Assay for CPT-1 Activity--
Cells were preincubated with or
without TDGA, a specific irreversible inhibitor of CPT-1, for 45 min
(20). Then the medium was aspirated, and cells were washed twice with
PBS. Cells were then treated with either genistein or H-89. After 45 min, cells were incubated with or without 10 ng/ml leptin and were
subsequently permeabilized with 700 µl of a medium containing 50 mM imidazole (pH 7.1), 70 mM KCl, 80 mM sucrose, 1 mM EGTA, 2 mM
MgCl2, 1 mM dithioerythritol, 1 mM
KCN, 1 mM ATP, and 0.1% (w/vol) defatted and dialyzed
bovine serum albumin (medium A), supplemented with 100 µl of 0.2 mg/ml digitonin. The medium was aspirated after 3 min, and reactions
were started by addition of 700 µl of medium A supplemented with 100 µl of 0.4 mM palmitoyl-CoA plus 1.2 mM L-[methyl-3H]carnitine. After
4-min incubation at 37 °C, the reactions were stopped with 0.8 ml of
2 N HCl, and [3H]palmitoylcarnitine product
was extracted with n-butanol (21).
Assay for Acetyl-CoA Carboxylase (ACC) Activity--
ACC
activity was determined in digitonin-permeabilized BAEC as the
incorporation of radiolabeled acetyl-CoA into fatty acids in a reaction
coupled to the fatty acid synthase reaction. Cells were pretreated with
or without either genistein or H-89 for 45 min and then treated with or
without 10 ng/ml leptin. Cells were washed twice with PBS and then
trypsinized. Reactions were subsequently started with 100 µl of cell
suspension plus 100 µl of assay mixture containing 126 mM
Hepes (pH 7.9), 21 mM NaCl, 4.2 mM
MgCl2, 1 mM citric acid, 20 mM
KHCO3, 4 mM ATP, 1 mM NADPH, 0.5 mM EGTA, 0.5 mM dithioerythritol, 1 mM KCN, 1 mM ATP, and 0.85% (w/v) defatted and
dialyzed bovine serum albumin, 125 µM butyryl-CoA, 125 µM [1-14C]acetyl-CoA, 3 munits of purified
rat fatty acid synthase and 0.39 mg/ml digitonin. After 5-min
incubation at 37 °C, the reactions were stopped with 100 µl of 10 N NaOH, and fatty acids were extracted by petroleum ether
(22).
MCP-1 Expression--
Cells were cultured with or without 10 ng/ml leptin in the presence or absence of genistein, H-89, Rp-cAMPS,
or TDGA for 24 h. MCP-1 content in the medium was analyzed using
an enzyme-linked immunosorbent assay kit derived from R&D systems
(Minneapolis, MN), according to the manufacturer's instruction.
PKA Assay--
Cells were incubated with or without 10 ng/ml
leptin for 45 min, lysed, and PKA activity was measured using a
commerical protein kinase A assay kit (Calbiochem) according to the
manufacturer's instructions.
cAMP Assay--
Cells were incubated with or without 10 ng/ml
leptin, lysed, and cAMP concentrations in whole-cell lysates were
determined using the cyclic Amp (3H) assay system (Amersham
Pharmacia Biotech, Arlington Heights, IL) according to the
manufacturer's instructions.
Statistical Analysis--
Data were analyzed using the
one-factor analysis of variance (ANOVA) procedure to compare the means
of all the groups. The Tukey-Kramer multiple comparisons procedure was
used to determine which pairs of means were different. Data are shown
as mean ± S.E.
Effects of Leptin on Intracellular ROS Production in BAEC--
To
determine the site of leptin-induced intracellular ROS production, BAEC
were incubated with either rotenone, an inhibitor of complex I, TTFA,
an inhibitor of complex II, or CCCP, an uncoupler of oxidative
phosphorylation that abolishes the mitochondrial membrane proton
gradient, MnTBAP, a stable cell-permeable SOD mimetic, UCP-1
HVJ-liposomes, or MnSOD HVJ-liposomes. Compared with basal conditions
(5 mM glucose), 10 ng/ml leptin increased ROS production to
about 2.3-fold (Fig. 1). Furthermore, all
the reagents were found to completely prevent the effects of leptin on
ROS production in BAEC, demonstrating that ROS generation arises from
mitochondrial electron transport chain.
We have very recently shown that hyperglycemia-induced ROS generation
also arises exclusively from the mitochondrial electron transport chain
(15). Therefore, we next investigated the additive effects of high
glucose and leptin on ROS production in BAEC. As shown in Fig.
2, leptin increased ROS production in a
dose-dependent manner at every concentrations of glucose
tested, and the effect was synergistic with that of glucose at the
highest leptin concentration.
Effects of Leptin on Glucose Transport, Glycolysis, and TCA
Cycle--
The effects of leptin on glucose transport activity of BAEC
was assayed with a glucose analogue, 2-DG, in confluent cultures preexposed to 10 ng/ml leptin for 45 min. Leptin did not affect the
uptake of 2-DG into BAEC (leptin-treated versus control
cells; 7.29 ± 0.2 versus 7.18 ± 0.34 µmol/mg/min). Intracellular glucose oxidation begins with glycolysis
in the cytoplasm, leading to the generation of pyruvate, which can also
be transported into the mitochondria where it is oxidized by the TCA
cycle. Therefore, we next investigated the effects of leptin on
glycolysis and the TCA cycle. Ten ng/ml leptin affected neither
glycolysis nor the TCA cycle in BAEC (glycolysis and TCA cycle of
leptin-treated versus control cells; 1.39 ± 0.36 versus 1.73 ± 0.16 nmol/mg/min and 0.131 ± 0.003 versus 0.123 ± 0.009 nmol/mg/min, respectively). These
results suggest that neither glycolysis nor the TCA cycle is the source
of increased ROS generation induced by leptin.
Effects of Leptin on Fatty Acid Oxidation in BAEC--
We next
investigated the effects of leptin on fatty acid oxidation in BAEC. For
this, BAEC were incubated with [14C]palmitate in the
presence or absence of leptin and then 14CO2
production was determined. Compared with basal conditions (5 mM glucose), 10 ng/ml leptin increased fatty acid oxidation about 1.5-fold (Fig. 3). Furthermore,
high glucose was found not to inhibit the leptin-induced increase in
fatty acid oxidation in BAEC. These results suggest that leptin
produces ROS generation through an increase of fatty acid oxidation
that is independent of glucose concentrations.
Effects of Leptin on CPT-1 and ACC Activity in BAEC--
CPT-1,
located in the mitochondrial outer membrane, catalyzes the pace-setting
step of long chain fatty acid translocation into the mitochondrial
matrix, and is a key regulatory site of fatty acid oxidation. We
investigated the effects of leptin on CPT-1 activity in BAEC. As shown
in Fig. 4, leptin increased CPT-1 activity about 1.7-fold. Genistein, an inhibitor of tyrosine kinases and H-89, an inhibitor of protein kinase A (PKA), completely prevented the leptin-induced increase in CPT-1 activity in BAEC. Because CPT-1 is
subject to inhibition by malonyl-CoA, the product of the reaction
catalyzed by ACC, a key regulatory enzyme of fatty acid synthesis, we
next studied the effects of leptin on ACC activity in BAEC. In contrast
to the case of CPT-1, leptin was found to decrease ACC activity to
about 50% of that of control cells (Fig. 5). Genistein or H-89 completely
prevented the leptin-induced decrease in ACC activity in BAEC. Rp-cAMPS
treatment similarly inhibited the leptin-induced increase in CPT-1 and
the decrease in ACC activity (data not shown). These results suggest
that activation of the leptin receptor tyrosine kinase increases fatty
acid oxidation by increasing CPT-1 activity and decreasing ACC activity
via PKA activation.
Effects of Genistein, H-89, Rp-cAMPS, or TDGA on Leptin-induced ROS
Production--
We next investigated whether the inhibition of fatty
acid oxidation induced by leptin could block leptin-induced ROS
generation in BAEC. As shown in Fig. 6,
genistein, H-89, Rp-cAMPS, or TDGA completely inhibited the production
of ROS induced by leptin. The results indicate that leptin-induced ROS
production is derived from PKA-induced fatty acid oxidation.
Effects of Genistein, H-89, Rp-cAMPS, or TDGA on Leptin-induced
MCP-1 Production in BAEC--
Because MCP-1 production is known to be
induced by ROS (14), we studied whether leptin can stimulate the
production of MCP-1 in BAEC. As shown in Fig.
7, compared with basal conditions (5 mM glucose), 10 ng/ml leptin increases the MCP-1 production
about 1.4-fold. Genistein, H-89, Rp-cAMPS, or TDGA was found to
completely inhibit the leptin-induced MCP-1 production in BAEC. The
results suggest that the leptin-induced ROS production enhances the
production of MCP-1 in BAEC by increasing fatty acid oxidation via PKA
activation.
Effect of Leptin on PKA Activity--
Because both H89 and
Rp-cAMPS blocked the effects of leptin on ROS and MCP-1 production, PKA
activity was directly measured in the presence and absence of 10 ng/ml
leptin. Leptin induced a 2-fold increase in PKA activity compared with
controls (56.0 ± 7.8 versus 27.2 ± 1.6 pmol/min/mg protein).
Effect of Leptin on cAMP Concentration--
To confirm that
leptin induced cAMP, levels were determined after leptin stimulation.
Leptin induced a 1.3-fold increase in cAMP in total cell lysate
(13.28 ± 1.08 versus 10.33 ± 1.25 pmol/mg protein, p < 0.03).
In this study, we found for the first time that leptin induces
mitochondrial superoxide production and MCP-1 expression in BAEC by
increasing fatty acid oxidation via PKA. Like the AMP-activated protein
kinase, PKA may stimulate CPT-1, a key enzyme of fatty acid oxidation,
by two mechanisms: one is by decreasing malonyl-CoA levels through
phosphorylation and inactivation of ACC, and the other is by modulating
the interactions between CPT-1 and the cytoskeleton through
phosphorylation of intermediate filaments in a malonyl-CoA-independent
manner (23, 24). Our results suggest that PKA activation is a key step
for the leptin-induced ROS generation in BAEC. According to the glucose
fatty acid cycle hypothesis of Randle (25), glucose oxidation inhibits
fatty acid oxidation. However, we did not observe this effect in our system. This likely reflects the fact that PKA and AMP-activated kinase
may inhibit ACC activation by citrate derived from glucose oxidation
and thus prevent the malonyl-CoA inhibition of CPT-1, which is the
basis for Randle cycle (25, 26). Thus, the additive effects of
leptin-induced fatty acid oxidation and glucose most likely reflect the
fact that hyperglycemia enhances ROS formation through increased
pyruvate oxidation in the TCA cycle (15), whereas leptin enhances ROS
formation through increased beta oxidation and oxidation of the
resultant acetyl-CoA through the TCA cycle.
Plasma levels of leptin in healthy subjects are less than 10 ng/ml. In
obese subjects and insulin resistant first-degree relatives of patients
with NIDDM, they are increased to 10-100 ng/ml, and similar values
have been reported in type I diabetes (3-5). In this study, 10 ng/ml
leptin was sufficient to nearly triple fatty acid-induced mitochondrial
overproduction of ROS. The effect of 10 and 100 ng/ml leptin was
further accentuated by diabetic levels of hyperglycemia. These data
suggest that hyperleptinemia accelerates atherosclerosis in obese
diabetic patients through ROS overproduction.
In insulin resistant states, the activity of hormone-sensitive lipase
in adipose tissues is known to be increased, contributing to the
elevation of free fatty acids (27). Therefore, the coexistence of
hyperleptinemia and insulin resistance-induced elevation of free fatty
acids may further enhance the ROS generation in vascular endothelial
cells, promoting atherosclerosis.
ROS is recently reported to up-regulate many genes that are involved in
various steps of atherosclerosis by inducing redox-sensitive transcriptional factors such as nuclear factor-
INTRODUCTION
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ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
and interleukin-6 (10, 11),
and plasminogen activator inhibitor-1, a serine protease inhibitor of
fibrinolysis, which together may play an active role in the
pathogenesis of accelerated atherosclerosis in diabetes (12-14). We
hypothesized that leptin is also one of the mediators promoting
atherosclerosis. We have very recently shown that hyperglycemia-induced
mitochondrial overproduction of reactive oxygen species (ROS) serves as
a causal link between elevated glucose and hyperglycemic vascular
damage (15). Therefore, we investigated the direct effects of leptin on
ROS generation, and the mechanism by which this induced expression of
the redox-sensitive chemokine, monocyte chemoattractant protein-1
(MCP-1) (16) in bovine aortic endothelial cells (BAEC).
EXPERIMENTAL PROCEDURES
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ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
RESULTS
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ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
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Fig. 1.
Effects of agents that alter mitochondrial
metabolism on leptin-induced ROS generation in BAEC. Cells were
preincubated with or without rotenone, TTFA, CCCP, or MnTBAP for 45 min, then treated with or without 10 ng/ml leptin for 45 min, and then
ROS was quantitated. Two days after transfection with HVJ-UCP-1 or
HVJ-MnSOD liposomes, cells were treated with or without 10 ng/ml leptin
for 45 min and then ROS was quantitated. *, p < 0.01 compared with cells incubated with 5 mM glucose
alone.
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Fig. 2.
Effects of various concentrations of glucose
and leptin on ROS generation in BAEC. Cells were incubated with
the indicated concentrations of glucose for 24 h and for the last
45 min with the indicated concentrations of leptin and then ROS was
quantitated. *, p < 0.01, #,
p < 0.01, or +, p < 0.01 compared with cells incubated with 5 mM glucose, 10 mM glucose, or 30 mM glucose alone,
respectively.
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Fig. 3.
Effects of leptin on fatty acid oxidation in
BAEC. Cells were prelabeled overnight with 50 µM
[1-14C]palmitic acid, and the conversion to
[14C]CO2 was quantitated under the indicated
conditions. *, p < 0.05 compared with cells incubated
with 5 mM glucose alone. #, p < 0.05 compared with cells incubated with 30 mM glucose
alone.
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Fig. 4.
Effects of leptin on CPT-1 activity.
Cells were pretreated with either genistein or H-89 for 45 min and then
incubated with 10 ng/ml leptin for 45 min. CPT-1 activity was measured
as described under "Experimental Procedures." Enzyme activities are
expressed as nmol of product/min/mg cell protein. *, p < 0.01 compared with cells incubated with 5 mM glucose
alone.
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Fig. 5.
Effects of leptin on ACC activity. Cells
were pretreated with either genistein or H-89 for 45 min and then
incubated with 10 ng/ml leptin for 45 min. ACC activity was measured as
described under "Experimental Procedures." Enzyme activities are
expressed as pmol of product/min/mg cell protein. *, p < 0.01 compared with cells incubated with 5 mM glucose
alone.
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Fig. 6.
Effects of genistein, H-89, Rp-cAMPS, or TDGA
on the leptin-induced ROS generation in BAEC. Cells were
preincubated with or without either genistein, H-89, Rp-cAMPS, or TDGA
for 45 min and then treated with or without 10 ng/ml leptin. After 45 min, ROS were quantitated. *, p < 0.01 compared with
cells incubated with 5 mM glucose alone.
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Fig. 7.
Effects of leptin on MCP-1 expression in
BAEC. Cells were incubated with or without 10 ng/ml leptin in the
presence or absence of either genistein, H-89, Rp-cAMPS, or TDGA for
24 h. Medium was collected and MCP-1 content in the medium was
analyzed with an enzyme-linked immunosorbent assay kit. *,
p < 0.01 compared with cells incubated with 5 mM glucose alone.
DISCUSSION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
B and activator protein-1 (28-30). Among these mediators, MCP-1, a CC chemokine, plays
an important role in the early phase of atherosclerosis by initiating
monocyte/macrophage recruitment to the vessel wall (31), and its
expression is actually known to be up-regulated in human
atherosclerotic plaques (32). Furthermore, the selective targeting of
CCR2, the receptor for MCP-1, was recently shown to markedly decrease
atheromataous lesion formation in apoE knockout mice (33). Therefore,
MCP-1 overproduction induced by leptin would promote fatty streak
formation, the earliest histopathological hallmark of atherosclerosis.
The elimination of ROS generation induced by leptin via fatty acid
oxidation may provide a new therapeutic strategy for the treatment of
accelerated atherosclerosis in diabetic patients.
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FOOTNOTES |
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* This study was supported by grants from the National Institutes of Health.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.
¶ To whom correspondence should be addressed: Dept. of Medicine, Diabetes Research Center, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461; E-mail: brownlee@aecom.yu.edu.
Published, JBC Papers in Press, May 7, 2001, DOI 10.1074/jbc.M007383200
2 TDGA was kindly given by Dr. J. M. Lowenstein (Brandeis University, Waltham, MA).
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ABBREVIATIONS |
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The abbreviations used are: NIDDM, non-insulin-dependent diabetes mellitus; ROS, reactive oxygen species; MCP-1, monocyte chemoattractant protein-1; BAEC, bovine aortic endothelial cells; TTFA, thenoyltrifluoroacetone; CCCP, carbonyl cyanide m-chlorophenylhydrazone; MnTBAP, 100 µM Mn(III)tetrakis (4-benzoic acid) porphyrin; UCP-1, uncoupling protein-1; MnSOD, manganese superoxide dismutase; Rp-cAMPS, the Rp diastereoisomer of adenosine 3', 5'-cyclic monophosphothionate, TDGA, tetradecylglycidate; 2-DG, 2-deoxy-D-glucose; PBS, phosphate-buffered saline; TCA, tricarboxylic acid; CPT-1, carnitine palmitoyltransferase-1; ACC, acetyl-CoA carboxylase; PKA, protein kinase A.
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