Deficiency in apolipoprotein E has a protective effect on
diet-induced nonalcoholic fatty liver disease in mice
Eleni A. Karavia
1
, Dionysios J. Papachristou
2
, Ioanna Kotsikogianni
2
, Ioanna Giopanou
2
and
Kyriakos E. Kypreos
1
1 Department of Medicine, Pharmacology Unit, University of Patras School of Health Sciences, Rio-Achaias, Greece
2 Department of Medicine, Anatomy, Histology and Embryology Unit, University of Patras School of Health Sciences, Rio-Achaias, Greece
Keywords
apoE-deficient mice; apolipoprotein E; low
density lipoprotein receptor; lipoproteins;
nonalcoholic fatty liver disease
Correspondence
K. E. Kypreos, Department of Medicine,
University of Patras School of Health
Sciences, Panepistimioupolis, Rio,
TK 26500, Greece
Fax: +302610994720
Tel: +302610969120
E-mail:
(Received 21 March 2011, revised 7 June
2011, accepted 6 July 2011)
doi:10.1111/j.1742-4658.2011.08238.x
Apolipoprotein E (apoE) mediates the efficient catabolism of the

chylomicron remnants and very low-density lipoprotein
(VLDL) [1]. The importance of this protein in
the maintenance of plasma lipid homeostasis and ath-
eroprotection was first established with the generation
of the apoE-deficient mouse [8,9], which develops
Abbreviations
apoE, apolipoprotein E; apoE
) ⁄ )
, apoE deficient; apoE3
knock-in
mice, mice containing a targeted replacement of the mouse apoE gene for the
human apoE3 gene; FFA, free fatty acid; HDL, high-density lipoprotein; IDL, intermediate density lipoprotein; LDL, low-density lipoprotein;
LDLr, low-density lipoprotein receptor; LDLr
) ⁄ )
, LDLr deficient; NAFLD, nonalcoholic fatty liver disease; VLDL, very low-density lipoprotein;
WT, wild-type.
FEBS Journal 278 (2011) 3119–3129 ª 2011 The Authors Journal compilation ª 2011 FEBS 3119
hypercholesterolemia and spontaneous atherosclerosis
[8,9].
Recently, using apoE-deficient (apoE
) ⁄ )
) mice,
C57BL ⁄ 6 mice and apoE3
knock-in
mice (mice containing
a targeted replacement of the mouse apoE gene for the
human apoE3 gene), we have shown that, in addition
to its role in the maintenance of plasma lipid homeo-
stasis, apoE plays a central role in the development of
diet-induced obesity and related metabolic dysfunc-

protein, 48.5% carbohydrate, 21.2% fat, 0.2% choles-
terol, 4.5 kcalÆg
)1
) for 24 weeks, and histological and
biochemical analyses were performed. We found that
deficiency in apoE has a protective effect on diet-
induced hepatic triglyceride accumulation, and the
apoE-mediated development of diet-induced NAFLD
in mice is independent of the low-density lipoprotein
receptor (LDLr). Our data establish that apoE plays a
central role in the deposition of post-prandial triglyce-
rides in the liver and NAFLD which, over long periods
of time, may lead to nonalcoholic steatohepatitis.
Results
apoE
) ⁄ )
mice are less sensitive than control
C57BL
⁄
6 mice to hepatic triglyceride
accumulation
To test the effects of apoE on hepatic triglyceride
accumulation, groups of 10–12-week-old male apoE
) ⁄ )
and WT C57BL ⁄ 6 mice were placed on a western-type
diet for a total period of 24 weeks. As shown
in Fig. 1A, hematoxylin and eosin staining of liver
AB
C D
Fig. 1. Histological analyses of liver

hematoxylin and eosin-stained sections revealed that
the number of lipid droplets within liver hepatocytes
was significantly elevated in C57BL ⁄ 6 relative to
apoE
) ⁄ )
mice (P = 0.0001). In agreement with these
data, staining of hepatic sections with reticulin showed
that, in C57BL ⁄ 6 mice fed a western-type diet for
24 weeks, NAFLD had progressed much more exten-
sively and had resulted in significant disruption in the
normal architecture of the extracellular reticulin fibrils
of the liver (Fig. 1D), relative to apoE
) ⁄ )
mice
(Fig. 1C) that displayed a normal hepatic histology.
No significant differences in the size and shape of vis-
ceral adipocytes were detected between the two groups
of mice (data not shown).
To further confirm that deficiency in apoE prevented
the accumulation of hepatic triglycerides in the liver of
mice fed a western-type diet for 24 weeks, liver sam-
ples were isolated from apoE
) ⁄ )
and C57BL ⁄ 6 mice
and their triglyceride contents were determined bio-
chemically, as described in the Materials and methods
section. This analysis showed that apoE
) ⁄ )
mice fed a
western-type diet for 24 weeks had a triglyceride

50
100
150
200
250
300
apoE
–/–
C57BL/6
**
**
**
**
Weeks
% of initial body weight
0
25
50
75
100
125
150
175
200
C57BL/6
apoE
–/–
**
Hepatic Triglyceride
content [mg Tg·(g tissue)

–1
)
0 1 2 3 4 5 6 7 8 9
0
1
2
3
4
5
6
7
8
9
10
Fraction number
Triglycerides (mg·dL
–1
)
CHYL/VLDL/IDL
HDL
0 1 2 3 4 5 6 7 8 9
0
25
50
75
100
125
150
175
200

FEBS Journal 278 (2011) 3119–3129 ª 2011 The Authors Journal compilation ª 2011 FEBS 3121
starting weight of 25.7 ± 0.2 g at week 0, P < 0.05).
At week 12, their average body weight was
30.7 ± 1.1 g and, at week 24, it showed a further
slight increase to 31.6 ± 1.7 g (19.7 ± 7.3% increase
relative to their starting weight at week 0, P < 0.05)
(Fig. 2A). In contrast, C57BL ⁄ 6 mice showed a signifi-
cant increase in their body weight during the course of
the experiment. At week 6, C57BL ⁄ 6 mice had an
average body weight of 31.8 ± 1.7 g (23.5 ± 3.9%
increase relative to their starting weight of 25.8 ± 1 g
at week 0, P < 0.05). At week 12, their body weight
was 35.3 ± 0.6 g and, at week 24, it showed a further
increase to 42.8 ± 1.7 g (66.7 ± 5.6% increase rela-
tive to their starting weight at week 0, P < 0.05)
(Fig. 2A). In agreement with our previous findings
[10], the increased body weight of C57BL ⁄ 6 mice cor-
responds to an increased body fat mass (data not
shown).
Plasma lipid levels and average daily food
consumption of mice fed a western-type diet for
24 weeks
To determine how plasma lipid levels may reflect differ-
ences in hepatic triglyceride accumulation in apoE
) ⁄ )
and C57BL ⁄ 6 mice, fasting plasma samples were iso-
lated every 6 weeks and cholesterol, triglyceride and free
fatty acid (FFA) levels were measured as described
in the Materials and methods section. As shown
in Fig. 2B, apoE

(79.4 ± 7.4 mgÆdL
)1
at week 24 versus 58.2 ±
1.1 mgÆdL
)1
at week 0) (Fig. 2C). Ultracentrifugation
analysis of plasma samples showed that the cholesterol
of these mice was mainly distributed in the high-density
lipoprotein (HDL) fractions (Fig. 2E,F).
Surprisingly, apoE
) ⁄ )
mice, which do not develop
NAFLD, had a higher plasma concentration of
FFAs than C57BL ⁄ 6 mice. Steady-state FFA levels
of apoE
) ⁄ )
mice were 7.6 ± 1.2 mmol eq., whereas
C57BL ⁄ 6 mice showed a much lower steady-state
plasma FFA concentration of 1.4 ± 0.1 mmol eq. (P =
0.0001).
To determine whether differences in hepatic triglycer-
ide accumulation could be explained by differences in
the average daily food consumption between the two
groups of mice, at weeks 12 and 24 of the experiment
we determined the average daily food consumption for
each mouse group. It was found that apoE
) ⁄ )
mice
consumed 3.3 ± 0.2 and 3.5 ± 0.6 gÆmouse
)1

intestinal triglyceride absorption in apoE
) ⁄ )
and
C57BL
⁄
6 mice
One mechanism that could affect the hepatic triglycer-
ide content is the secretion of hepatic triglycerides in
the circulation. To determine the contribution of VLDL
triglyceride secretion in apoE-mediated hepatic lipid
accumulation, we compared the rate of hepatic VLDL
triglyceride secretion between apoE
) ⁄ )
and C57BL ⁄ 6
mice. In accordance with previous studies [19–21], we
found that the rate of hepatic triglyceride secretion
decreased significantly in apoE
) ⁄ )
relative to C57BL ⁄ 6
mice. Specifically, secretion rates were 2.1 ± 0.4 mgÆ-
dL
)1
Æmin
)1
(minimum, 1.7 mgÆdL
)1
Æmin
)1
; maximum,
3.5 mgÆdL

NAFLD could be increased intestinal secretion of
Apolipoprotein E and diet-induced NAFLD E. A. Karavia et al.
3122 FEBS Journal 278 (2011) 3119–3129 ª 2011 The Authors Journal compilation ª 2011 FEBS
triglyceride-rich lipoproteins in the plasma of these
mice. To determine the rate of intestinal triglyceride
secretion, we calculated the total rate (intestinal and
hepatic) of plasma triglyceride input in apoE
) ⁄ )
and
C57BL ⁄ 6 mice fed a western-type diet, following an
oral fat load. Groups of five apoE
) ⁄ )
and C57BL ⁄ 6
mice were fasted for 16 h, and then given an oral fat
load of 300 lL of olive oil, as described in the Materi-
als and methods section. One hour post-gavage, mice
were injected with Triton WR1339 and plasma triglyc-
eride levels were determined as a function of time. As
shown in Fig. 3B, apoE
) ⁄ )
mice showed a lower rate
of total triglyceride input than C57BL ⁄ 6 mice. Specifi-
cally, the rates were 11.9 ± 1.3 mgÆdL
)1
Æmin
)1
for
apoE
) ⁄ )
mice and 14.5 ± 1.2 mgÆdL

⁄
6 mice
Another potential mechanism that could explain the
reduced sensitivity of apoE
) ⁄ )
mice to diet-induced
NAFLD could be reduced clearance of plasma trigly-
cerides in these mice. Thus, in the next set of
experiments, we sought to determine the kinetics of
post-prandial triglyceride clearance. As shown in
Fig. 3C, following gavage administration of olive oil,
the mouse groups reached similar maximum plasma
concentrations of 142.7 ± 29.6 and 161.4 ± 21.5
mgÆdL
)1
, respectively, at 120 min post-gavage (n =5,
P = 0.2195) (Fig. 3C). However, there was a signifi-
cant difference in post-prandial triglyceride clearance
in apoE
) ⁄ )
mice relative to C57BL ⁄ 6 mice. In particu-
lar, in C57BL6 mice, the rapid increase in plasma
triglyceride levels at 120 min after olive oil administra-
tion was followed by an immediate and steep decline.
At 240 min post-gavage, the plasma triglycerides of
C57BL ⁄ 6 mice reached baseline levels
(59.5 ± 10.7 mgÆdL
)1
; minimum, 20.7 mgÆdL
)1

low density lipoprotein receptor-deficient (LDLr
) ⁄ )
)
mice were fed a western-type diet for 24 weeks and
liver specimens were isolated and analyzed for triglyc-
eride content by biochemical and histological analyses.
apoE
–/–
C57BL/6
0
5
10
15
**
Rate of hepatic
VLDL-triglyceride
secretion (mg·dL
–1
·min
–1
)
60 90 120 150 180
0
500
1000
1500
2000
apoE
–/–
C57BL/6

**
**
Time post-gavage (min)
Plasma triglycerides
(mg·dL
–1
)
A
B
C
Fig. 3. Analysis of kinetic parameters associated with hepatic tri-
glyceride content. (A) Rate of hepatic very low-density lipoprotein
(VLDL) triglyceride secretion. (B) Rate of total triglyceride supply in
plasma in apolipoprotein E-deficient (apoE
) ⁄ )
)(h) and C57BL ⁄ 6(m)
mice. (C) Kinetics of post-prandial triglyceride clearance in apoE
) ⁄ )
(h) and C57BL ⁄ 6( ) mice. **P < 0.005.
E. A. Karavia et al. Apolipoprotein E and diet-induced NAFLD
FEBS Journal 278 (2011) 3119–3129 ª 2011 The Authors Journal compilation ª 2011 FEBS 3123
In agreement with our previous studies, LDLr
) ⁄ )
mice
were more susceptible than apoE
) ⁄ )
mice to diet-
induced obesity, but more resistant than C57BL ⁄ 6
mice [10]. Surprisingly, however, we found that hepatic
specimens from LDLr

eosin staining of liver sections from control mice
revealed increased levels of steatosis, as demonstrated
by the existence of a large number of lipid droplets
within the vast majority of the examined hepatocytes.
Steatosis was diffuse and of the macrovesicular type,
in which a large fat vacuole within the hepatocyte
pushed the nucleus towards the edge of the cell. In
contrast, however, hematoxylin and eosin-stained liver
sections from apoE
) ⁄ )
mice showed a normal micro-
scopic appearance, the liver architecture was normal
and there was no evidence of lipid accumulation within
hepatocytes. Our histological findings were in harmony
with the results obtained by reticulin staining, which
showed that, in the liver of apoE
) ⁄ )
mice, the reticulin
network was not distorted, in contrast with the liver of
C57BL ⁄ 6 mice, which showed heavy loading with fat.
The reticulin stain is a classical histopathological mar-
ker for the identification of hepatic architecture and
structural damage within the liver parenchyma. There-
fore, the presence of more extensive reticulin network
in Fig. 1C indicates that, in apoE
) ⁄ )
mice, the reticulin
network is better preserved, further confirming that the
structural damage in the liver of these animals is mini-
mal following feeding with a high-fat diet. In contrast,

3124 FEBS Journal 278 (2011) 3119–3129 ª 2011 The Authors Journal compilation ª 2011 FEBS
intestinal dietary triglycerides in the liver of the experi-
mental mice. In general, hepatic triglyceride content is
a function of three parameters: (a) dietary triglyceride
deposition in the liver; (b) endogenous triglyceride syn-
thesis and turnover; and (c) hepatic VLDL triglyceride
secretion in the circulation. Endogenous triglyceride
clearance and turnover cannot account for the
observed differences between apoE
) ⁄ )
and C57BL ⁄ 6
mice as it is well established that intracellular triglycer-
ide turnover and synthesis, as well as the activities of
diacylglycerol acyltransferase and microsomal triglycer-
ide transfer protein, are comparable between apoE
) ⁄ )
and WT C57BL ⁄ 6 mice [22]. Similarly, differences in
the rate of hepatic VLDL triglyceride secretion
between apoE
) ⁄ )
and C57BL ⁄ 6 mice could not explain
the observed resistance of apoE
) ⁄ )
mice to diet-
induced NAFLD. Consistent with previous data
[19–21,23], we found that apoE
) ⁄ )
mice displayed
approximately five times slower hepatic VLDL triglyc-
eride secretion compared with control C57BL ⁄ 6 mice

in
apoE
) ⁄ )
mice; P < 0.05). However, apoE
) ⁄ )
mice dis-
played a significantly slower clearance of post-prandial
triglycerides from the circulation, consistent with a
slower rate of dietary lipid deposition in the liver and
other peripheral tissues.
Previously, it has been suggested that 3–4-month-old
apoE
) ⁄ )
mice on a chow diet have a slightly higher
hepatic triglyceride content relative to control mice
[22]. Our results showed that the slightly higher base-
line hepatic triglyceride content of apoE
) ⁄ )
mice fed a
chow diet does not predispose these mice to increased
sensitivity to NAFLD. In contrast, we found that
apoE deficiency renders these mice less sensitive to
hepatic triglyceride accumulation following feeding
with a high-fat diet. A more recent study has suggested
that hypercholesterolemia sensitizes apoE
) ⁄ )
mice to
carbon tetrachloride-mediated liver injury [24]. Our
data show that the hypercholesterolemia of apoE
) ⁄ )

diet remained within normal values (< 150 mgÆdL
)1
),
although they were elevated compared with those of
C57BL ⁄ 6 mice for the duration of the experiment. It is
well established that apoE is a potent inhibitor of
plasma lipoprotein lipase [26–28], and that lipolysis-
mediated release of FFAs is more efficient in apoE
) ⁄ )
mice than in apoE-expressing C57BL ⁄ 6 mice [27]. In
agreement with these studies, apoE
) ⁄ )
mice showed
elevated plasma FFA levels relative to C57BL ⁄ 6 mice
(apoE
) ⁄ )
mice had steady-state FFA levels of
7.6 ± 1.2 mmol eq., whereas C57BL ⁄ 6 mice had a
much lower steady-state plasma FFA concentration of
1.4 ± 0.1 mmol eq.; P < 0.005). Despite this apparent
increase in lipoprotein lipase-mediated FFA produc-
tion and in steady-state plasma FFA levels, our
apoE
) ⁄ )
mice were resistant to diet-induced NAFLD
and obesity. Thus, our data do not support the notion
that elevated plasma FFAs are pivotal for the accumu-
lation of triglycerides in the liver of experimental mice
[29,30], and that enhanced plasma lipoprotein lipase
activity promotes the deposition of plasma triglycerides

from the circulation [28], it is possible that the ability
of apoE to promote the deposition of hepatic triglyce-
rides in the liver is associated with its lipoprotein-clear-
ing function.
Our data extend our current knowledge on NAFLD
development. Although additional experiments will be
needed in order to determine whether receptors medi-
ate the effects of apoE, our data clearly support a new
function of apoE as a key peripheral contributor to
hepatic lipid deposition and the development of diet-
induced NAFLD in mice.
Materials and methods
Animal studies
The apoE
) ⁄ )
[9], LDLr
) ⁄ )
[35] and C57BL ⁄ 6 mice were
purchased from Jackson Laboratories (Bar Harbor, ME,
USA; ); apoE
) ⁄ )
mice were bred on the
C57BL ⁄ 6 background for at least 10 generations. Male
mice, 10–12 weeks of age, were used in these studies. All
animals were housed separately (one mouse per cage) and
allowed free access to food and water. To ensure similar
average cholesterol, triglyceride and glucose levels and
starting body weights for all animal experiments, groups of
five mice (n = 5) were formed after determining the fasting
cholesterol, triglyceride and glucose levels, and body

the Laboratory Animal Center of The University of Patras
Medical School.
Plasma lipid determination
Following a 16-h fasting period, plasma cholesterol, triglyc-
eride and FFA levels were measured as described previously
[36].
Fractionation of plasma lipoproteins by density
gradient ultracentrifugation
Pools (0.5 mL) of plasma from five apoE
) ⁄ )
and five
C57BL ⁄ 6 mice were fractionated by density gradient ultra-
centrifugation over a 10-mL KBr density gradient, as
described previously [37].
Body weight determination and body mass
composition analysis
Body weight and body composition analyses were per-
formed as described previously [10].
Measurement of hepatic triglyceride content
For hepatic triglyceride determination, a liver sample was
collected, weighed and dissolved in 0.5 mL of 5 m KOH in
50% ethanol solution by overnight incubation at 65 °C.
The solution was adjusted to pH 7, and the final volume
was recorded. The total amount of triglycerides was deter-
mined in the resulting mixture as described above. The
results are expressed as milligrams of triglycerides per gram
of tissue ± SEM.
Histological analysis of liver samples
At the end of the 24-week period, mice were sacrificed, and
liver and visceral fat specimens were collected and stored at

surements, as described previously [38].
Determination of post-prandial triglyceride
kinetics following the oral administration of olive
oil
Groups of five apoE
) ⁄ )
and C57BL ⁄ 6 mice were tested.
Prior to the experiment, mice were fasted overnight for
16 h. On the following day, the animals were given an oral
load of 0.5 mL of olive oil, and plasma samples were iso-
lated 30, 60, 120, 180 and 240 min following olive oil
administration. A control sample for baseline triglyceride
determination was isolated 1 min prior to the gavage
administration of olive oil. Triglyceride levels were quanti-
fied in plasma samples as described above, and then plotted
on graphs as a function of time. Values were expressed as
mgÆdL
)1
± SEM.
Rate of secretion of triglyceride-rich
chylomicrons and VLDL
To determine the rate of intestinal triglyceride secretion in
the plasma of our experimental mice, we measured the total
rate of plasma triglyceride input (intestinal and hepatic)
and subtracted the rate of hepatic triglyceride secretion.
Briefly, to determine the total rate of triglyceride input
in the plasma of mice, groups of five apoE
) ⁄ )
and
C57BL ⁄ 6 mice were tested. Prior to the experiment, the

tion, groups of four to six apoE
) ⁄ )
and C57BL ⁄ 6 mice were
injected with Triton-WR1339 at a dose of 500 mgÆ(kg body
weight)
)1
using a 15% solution (w ⁄ v) in 0.9% NaCl, as
described previously [26,36,37,40].
Subtraction of the rate of hepatic triglyceride secretion
from the total plasma triglyceride supply yielded the rate
of intestinal secretion of triglyceride-rich chylomicrons
following an oral fat load, expressed as the mean ±
SEM.
Statistical analysis
Comparison of the data from the two groups of mice
was performed using Student’s t-test. When more than a
two-group comparison was required, the results were ana-
lyzed using ANOVA. Data are reported as the mean ±
SEM; n indicates the number of animals tested in the
group.
Acknowledgements
This work was supported by the European Commu-
nity’s Seventh Framework Program [FP7 ⁄ 2007-2013]
grant agreement PIRG02-GA-2007-219129, The Uni-
versity of Patras Karatheodoris research grant (both
awarded to K.E.K.) and the European Community’s
Seventh Framework Program [FP7 ⁄ 2007-2013] grant
agreement PIRG02-GA-2009-256402 (awarded to
D.J.P.). This work was part of the activities of
the research network ‘MetSNet’ for the study of

Weisgraber KH, Havel RJ, Goldstein JL, Brown MS,
Schonfeld G, Hazzard WR et al. (1982) Proposed
nomenclature of apoE isoproteins, apoE genotypes, and
phenotypes. J Lipid Res 23, 911–914.
7 Zannis VI & Breslow JL (1982) Apolipoprotein E. Mol
Cell Biochem 42, 3–20.
8 Plump AS, Smith JD, Hayek T, Aalto-Setala K, Walsh
A, Verstuyft JG, Rubin EM & Breslow JL (1992)
Severe hypercholesterolemia and atherosclerosis in apo-
lipoprotein E-deficient mice created by homologous
recombination in ES cells. Cell 71, 343–353.
9 Zhang SH, Reddick RL, Piedrahita JA & Maeda N
(1992) Spontaneous hypercholesterolemia and arterial
lesions in mice lacking apolipoprotein E. Science 258,
468–471.
10 Karagiannides I, Abdou R, Tzortzopoulou A, Voshol
PJ & Kypreos KE (2008) Apolipoprotein E predisposes
to obesity and related metabolic dysfunctions in mice.
FEBS J 275, 4796–4809.
11 Kypreos KE, Karagiannides I, Fotiadou EH, Karavia
EA, Brinkmeier MS, Giakoumi SM & Tsompanidi EM
(2009) Mechanisms of obesity and related pathologies:
role of apolipoprotein E in the development of obesity.
FEBS J 276, 5720–5728.
12 Gao J, Katagiri H, Ishigaki Y, Yamada T, Ogihara T,
Imai J, Uno K, Hasegawa Y, Kanzaki M, Yamamoto
TT et al. (2007) Involvement of apolipoprotein E in
excess fat accumulation and insulin resistance. Diabetes
56, 24–33.
13 Hofmann SM, Zhou L, Perez-Tilve D, Greer T, Grant

20 Huang Y, Liu XQ, Rall SC Jr, Taylor JM, von
Eckardstein A, Assmann G & Mahley RW (1998) Over-
expression and accumulation of apolipoprotein E as a
cause of hypertriglyceridemia. J Biol Chem 273, 26388–
26393.
21 Tsukamoto K, Maugeais C, Glick JM & Rader DJ
(2000) Markedly increased secretion of VLDL triglyce-
rides induced by gene transfer of apolipoprotein E iso-
forms in apoE-deficient mice. J Lipid Res 41, 253–259.
22 Mensenkamp AR, Van Luyn MJ, Havinga R, Teusink
B, Waterman IJ, Mann CJ, Elzinga BM, Verkade HJ,
Zammit VA, Havekes LM et al. (2004) The transport
of triglycerides through the secretory pathway of he-
patocytes is impaired in apolipoprotein E deficient mice.
J Hepatol 40, 599–606.
23 Mensenkamp AR, Jong MC, van Goor H, Van Luyn
MJ, Bloks V, Havinga R, Voshol PJ, Hofker MH, Van
Dijk KW, Havekes LM et al. (1999) Apolipoprotein E
participates in the regulation of very low density
Apolipoprotein E and diet-induced NAFLD E. A. Karavia et al.
3128 FEBS Journal 278 (2011) 3119–3129 ª 2011 The Authors Journal compilation ª 2011 FEBS
lipoprotein-triglyceride secretion by the liver. J Biol
Chem 274, 35711–35718.
24 Ferre N, Martinez-Clemente M, Lopez-Parra M, Gonz-
alez-Periz A, Horrillo R, Planaguma A, Camps J, Joven
J, Tres A, Guardiola F et al. (2009) Increased susceptibil-
ity to exacerbated liver injury in hypercholesterolemic
ApoE-deficient mice: potential involvement of oxysterols.
Am J Physiol Gastrointest Liver Physiol 296, G553–G562.
25 Ma KL, Ruan XZ, Powis SH, Chen Y, Moorhead JF &

Acta 1791, 479–485.
32 Yamamoto T, Choi HW & Ryan RO (2008) Apolipo-
protein E isoform-specific binding to the low-density
lipoprotein receptor. Anal Biochem 372, 222–226.
33 Kypreos KE & Zannis VI (2006) LDL receptor defi-
ciency or apoE mutations prevent remnant clearance
and induce hypertriglyceridemia in mice. J Lipid Res 47,
521–529.
34 Yang MH, Son HJ, Sung JD, Choi YH, Koh KC, Yoo
BC & Paik SW (2005) The relationship between apoli-
poprotein E polymorphism, lipoprotein (a) and fatty
liver disease. Hepatogastroenterology 52, 1832–1835.
35 Ishibashi S, Brown MS, Goldstein JL, Gerard RD,
Hammer RE & Herz J (1993) Hypercholesterolemia in
low density lipoprotein receptor knockout mice and its
reversal by adenovirus-mediated gene delivery. J Clin
Invest 92, 883–893.
36 Kypreos KE, Van Dijk KW, van Der ZA, Havekes LM
& Zannis VI (2001) Domains of apolipoprotein E con-
tributing to triglyceride and cholesterol homeostasis
in vivo. Carboxyl-terminal region 203–299 promotes
hepatic very low density lipoprotein-triglyceride secre-
tion. J Biol Chem 276, 19778–19786.
37 Kypreos KE (2008) ABCA1 promotes the de novo bio-
genesis of apolipoprotein CIII-containing HDL particles
in vivo and modulates the severity of apolipopro-
tein CIII-induced hypertriglyceridemia. Biochemistry 47,
10491–10502.
38 Duivenvoorden I, Teusink B, Rensen PC, Romijn JA,
Havekes LM & Voshol PJ (2005) Apolipoprotein C3