Ahlke Heydemann University of Illinois at Chicago Physiology and Biophysics [email protected] The MRL mouse strain is naturally resistant to high fat diet-induced hyperglycemia
Dec 30, 2015
Ahlke HeydemannUniversity of Illinois at Chicago
Physiology and [email protected]
The MRL mouse strain is naturally resistant to high fat diet-induced
hyperglycemia
MRLC57
day 3
3d
ay 2
0d
ay 9
day 1
Clark 1998
The super healing wild type MRL mouse
1) Heal ear punches used for identification
Heal all tissues; cartilage, blood vessels, glands, hair follicles, nerves
2) No fibrosis when breed to have muscular dystrophy
Mouse tissues stained with Masson’s trichrome at 8 weeks old. Blue represents fibrotic scar tissue. Very rare in the MRL mice on the right.
Heydemann 2012
Mull 2014
B6 CD B6 HFD MRL CD MRL HFD0
5
10
15
20
25
30
35
40
45
Perc
ent b
ody
fat m
ass
p<0.01
MRL HFDMRL CD
B6 CD B6 HFD
p<0.05
spinespine
spine spine
fem
ur
femur
femur
femur
3) The MRL and B6 mice gain equal amounts of fat and weight.
When put on a 12 week high fat diet. Fat appears white in dual energy X-ray (top). Quantified in the bottom panel.
But they are…
Mull 2014
4) Resistant to HFD mediated type 2 diabetes pathology
When challenged with a glucose bolus the HFD MRL mice cleared the glucose quickly, like the control diet mice.
B6 CD B6 HFD MRL CD MRL HFD0
100
200
300
400
500
600
700
AU
C 1
.5 h
our
blo
od g
lucose
Mull, 2014
p<0.0001
p<0.0001
The MRL mice
5) Are also susceptible to autoimmune diseases.
6) Contain 2 mitochondrialheteroplasmies (Sachadyne2008)
Serum analysis of 6hour fasted animals at end of 12 week
diets
B6 CD B6 HFD MRL CD MRL HFD0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6In
sulin
ng/
ml
P=0.001
A
B6 CD B6 HFD MRL CD MRL HFD0
1
2
3
4
5
6
7
adip
onec
tin n
g/m
l
Bp<0.0001
p<0.01
p<0.0005
B6 CD B6 HFD MRL CD MRL HFD0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
free
fatt
y ac
id p
Mol
es/u
l
C p<0.05
Mull, 2014
Mull, 2014
B6 CD B6 HFD MRL CD MRL HFD0
0.5
1
1.5
2
2.5
3
3.5
tric
ep p
AMPK
arbi
trar
y un
its
B6 CD B6 HFD MRL CD MRL HFD0
0.5
1
1.5
2
2.5
3
3.5
quad
ricep
s pAM
PKar
bitr
ary
units
p<0.001
p<0.0001
C
D
pAMPK quantitation of 6 hour fasted
animals
Mull, 2014
Quadriceps Tissue
AMPK
pAMPK
B6 MRL
CD CDHFD HFD
pAMPK
Rel
ativ
e p
AM
PK
B6 CD B6 HFD MRL CD MRL HFD0
5
10
15
20
p=0.0194 AMPK
Rel
ativ
e A
MP
K
B6 CD B6 HFD MRL CD MRL HFD0
5
10
15
20
25p=0.0194
Liver tissue of 6 hour fasted animals at end of 12 week diets
Glycogen Assay
um
ole
s g
luc
os
yl
un
its
pe
r g
ram
we
t w
eig
ht
B6 CD B6 HFD MRL CD MRL HFD D2 CD D2 HFD0
20
40
60
80
p=0.0029p=0.0191
Liver Glycogen Assayafter 12 week diet, 6 hour fast
B6 CD (n=8)
B6 HFD (n=18)
MRL CD (n=7)
MRL HFD (n=15)
0
1
2
3
4
5
6
7
8LV
Mas
s /
Tibi
a Le
ngth
p=0.015
Heart size
B6 CD B6 HFD MRL CD MRL HFD
pAM
PK (a
rbita
ry u
nits
)
B6 CD B6 HFD MRL CD MRL HFD
AMPK
(arb
itary
uni
ts)
*
*
Cardiac; pAMPK comparison (n=9)
* p<0.05
**
B6 CD B6 HFD MRL CD MRL HFD
HK
II (
arb
itary
un
its)
***
***
*
Cardiac; HKII comparison (n=6)
* p<0.05, *** p<0.0005
B6 CD B6 HFD MRL CD MRL HFD
GLU
T4 (a
rbitr
ary
units
)Cardiac; Glut 4 comparison (n=3)
*
*
* p<0.05
CD B6
HFD MRLCD MRL
HFD B6
** +
+
Heart
MRL mitochondrial heteroplasmies
• One mitochondria and cell containing more than one mitochondrial genome.
• MRL mice have 2; T3900C and an adenine tract length insert (Sachydyn 2008).–MRL cytosine at 3900–MRL more than 8 adenines in the tract
• Inherited from the mother• Inherited independently• Polymorphisms in tRNAMet and tRNAArg
Quadriceps Heart Diaphragm Abdominals0
5
10
15
20
25
D2
MRL/D2 0%MRL mito
MRL/D2 100%MRL mito
hyd
roxyp
rolin
e n
M/m
g t
issu
eMuscular dystrophy
fibrosis
6 7 8 9 10 11 12 130
0.5
1
1.5
2
Remaining ear wound sizeand adenine tract length
CD MRL, p<0.05
Adenine tract length
mm
2
10 20 30 40 50 60 70 80 90 100200
220
240
260
280
300 AUC weekly weightAnd % cytosines, HFD MRL, p<0.01
% Cytosine at 3900
wei
ghts
(g x
wee
k)
0 10 20 30 40 50 60 70 80100
120
140
160
Average weekly blood glucose and % cytosines, HFD MRL, p<0.02
% Cytosine at 3900
we
ek
ly f
asti
ng
BG
, m
g/d
L
0 10 20 30 40 50 60 70 80 90 10050
100
150
200Average blood glucose post ITT
and % cytosines, CD MRL, p<0.01
% Cytosine at 3900
2 ho
ur a
verg
ae b
lood
glu
cose
Mitochondrial DNA Correlations
Four pure-breeding resultant mouse lines;nucMmitoM Sgcg +/-nucMmitoD Sgcg +/-nucDmitoM Sgcg +/-nucDmitoD Sgcg +/-
Early generation sib-crosseswild type mice; ear wound healing (2mm ear punch)HFD, metabolic profile *Sgcg-/- mice; Muscular Dystrophy panel ** genome wide association studies with mitochondrial content as a covariate
Late generation sib-crosseswild type mice; ear wound healing HFD, metabolic profileSgcg-/- mice; Muscular Dystrophy panel
Male FemaleP1 D Sgcg-/- x MRL
F1 nucM50D50mitoM, Sgcg+/- x MRL
N1 (nucM75D25mitoM, Sgcg+/-)2 xMRLN2 nucM88D12mitoM, Sgcg+/- x MRL
N3 nucM94D6mitoM, Sgcg+/- x MRL
N4 (nucM97D3mitoM, Sgcg+/-)2 x MRL
Current andfuture plans
Tirsit K. BerhanuNathan W. Roberts
Aaron J. MullJenan Holley-Cuthrell
Magdalis Vega-Gonsalez
ConclusionsWild type MRL mice can heal ear wounds, heal cardiac
cryo-injuries, resist muscular dystrophy-mediated fibrosis, resist high fat diet-mediated type 2 diabetes.
Multiple pieces of data indicate MRL-introducedmitochondrial heteroplasmies beneficially alter metabolism.
Mull, Figure 2
B6 CD B6 HFD MRL CD MRL HFD05
1015202530354045
Fat m
ass/
Body
mas
s %p<0.01
p<0.05
femur
MRL HFDMRL CD
B6 CD B6 HFD spinespine
spine spine
femur
femur
femur
Rel
ativ
e p
AM
PK
/AM
PK
Rat
io
B6 CD B6 HFD MRL CD MRL HFD0
1
2
3
4
pAMPK/AMPK Ratio
p=0.0192
p=0.0252
Upstream stimulatory factors and downstream targets of AMPK in the heart.
Beauloye C et al. Cardiovasc Res 2011;90:224-233
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