View
217
Download
0
Category
Preview:
Citation preview
Institut de recherches cliniques de Montréal (IRCM)110, avenue des Pins ouestMontréal (Québec) CanadaH2W 1R7
September 25, 200963rd High Blood Pressure Conference 2009Lewis K. Dahl Memorial Lecture
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Affiliated to Université de Montréal
No relationship to disclose
Lewis K. Dahl: Web visibility…
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Lewis K. Dahl: Web visibility…
Lewis K. Dahl: enduring contributions
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Comparison of hypertension among geographically distinct populations with different salt intake levels• review published in:
Cottier P, Bock KD: Essential Hypertension—an InternationalSymposium. Berlin: Springer, 1960, pp. 53–65
• reprinted in: Int. J. Epidemiol. 34: 967–972 (2005)
Demonstration of the role of genetic factors in susceptibility to experimental hypertension due to chronic excess salt
• Nature 194: 480-482 (1962)• J. Exp. Med. 115: 1173-1190 (1962)• discussed in recent editorial: J. Exp. Med. 204: 1507 (2007)
Selective breeding program to establish genetic experimental models of salt-sensitive hypertension
• New rat strains: Dahl-S and Dahl-R• further established into inbred rat strains by J.R. Rapp• used in numerous animal genetic studies
Novel inbred rat strains: WKHT and WKHA
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
XWKY SHR
F1
F2
Syst. BP: ≡
WKY
Activity: > WKY, ≡
SHR
HW/BW: > WKY, < SHR
Phenotype selection followed by inbreeding
WKHA WKHT
Cross performed by E.D. Hendley (U. of Vermont)
Syst. BP: > WKY, ≡
SHR
Activity: ≡
WKY, < SHR
HW/BW: > WKY, < SHR
Note: WKHA are not “hyperactive”
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
WKY
SHR
WKHA
LEWISWISTAR
0
200
400
600
800
1000
rat strain
Loco
mot
or a
ctiv
ity
⇒ one should be cautious not to define quantitative phenotypes as “normal” or “abnormal” in absolute terms, but only in comparison to other phenotypes within a species
WKHA have concentric LVH vs. WKY
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
ANF in ventricles
Ventricular weight0
50
100
150
200
250
fmol
e / m
g w
et w
eigh
t
2.90
3.10
3.30
3.50
Ven
tr. w
eigh
t / b
ody
wei
ght
WKY WKHAAdditional observation: LV concentration of ANF correlates negatively with LV weight → → → →
F2 intercross between WKY and WKHA
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
F2
F1 X X
P1 P2n
phenotype
n
phenotype
X
n
n
phenotype
phenotype
F2 GENETIC INTERCROSS
* *
*
*** variance = environment** variance = environment x genetics
F2
F1 X XF1 X X
P1 P2n
phenotype
n
phenotype
X
n
n
phenotype
phenotype
F2 GENETIC INTERCROSS
* *
*
*** variance = environment** variance = environment x genetics
Co-segregation analysis in F2 population
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
L.V. weight / body weight tertile
lower mid higherlower mid higher40
60
80
100
120
fmol
e / m
g w
et w
eigh
t
ANF peptide
(31)
(72)
(41)
lower mid higher0.70
0.95
1.20
O.D
. rat
io
β-MHC mRNA
(30)
(23)
(24)
0.20
0.45
0.70
O.D
. rat
io
ANF mRNA
(18)
(45)
(25)
Circ. Res., 84:1453-1458 (1999)
Detection of QTLs for LVM and LV ANF
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
0 20 40 60 80 100 1200
1
2
3
4
5
LOD
(L.V
. mas
s)
0 20 40 60 80 100 1200
5
10
15
LOD
[ln(
vent
r. A
NF)
]
Mgh1 Rat126 Mgh3 Rat28 Rat173 Mgh8 Rat99Wox10 Rat245
Rat180
1-LOD interv.
1-LOD interv.
QTL/ANFv
QTL/LVM
a
b
Circ. Res. 88:222-227, 2001
→ One of the first examples of an “expression QTL in cis” (cis-eQTL) co-mapping with a whole organ QTL
Additional finding: SNP in Nppa promoter alters transcriptional activity
Physical confirmation of QTL in congenic rats
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Physiol Genomics 12:61-67, 2002
←
“Cm24”
Natriuretic peptide signaling
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Heart-specific guanylate cyclase transgene
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Not I Xho I(Start) (Stop) (A)n
α-MHC prom CAT - GC Rabbit -globinβ
brain
heart
kidne
y
liver
muscle
lungsto
mach
splee
n
18s
18s
Str. 09
Str. 19
GC cGMP0
200
400
600
800
fmol
/ mg
prot
NT
TG*
*
J. Biol. Chem. 278:47694, 2003
Not I Xho I(Start) (Stop) (A)n
α-MHC promα-MHC prom CAT - GC Rabbit -globinβRabbit -globinβ
brain
heart
kidne
y
liver
muscle
lungsto
mach
splee
n
18s
18s
Str. 09
Str. 19
GC cGMP0
200
400
600
800
fmol
/ mg
prot
NT
TG*
*
J. Biol. Chem. 278:47694, 2003
The cardiac GC transgene blocks the hypertrophic effects of aortic constriction on:
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
NT TG4
5
6
7
ratio
HW/BW
NT TG50
75
100
125
mm
x 1
0-2
IVSW
NT TG50
75
100
125
mm
x 1
0-2
LVPW
**
SHAM AAC
NT TG15
20
25
30
µm
cardiomyocyte width
NT TG1000
2000
3000
4000
5000
6000
µm 2
cardiomyocyte surface
***
******
**
SHAM AAC
LV weight →
LV wall thickness →
Surface area of isolated cardiomyocytes →
J. Biol. Chem. 278:47694, 2003
The QTL Cm24 has no effect on LVM of female rats under basal conditions….
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Physiol Genomics 12:61-67, 2002
…but Cm24 increases the effect of volume overload on adverse LV remodeling in female rats
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Hypertension, 47:128-133, 2006
Sex-specificity of QTLs linked to LVM
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Mamm. Genome 16: 700-711 (2005)
Where do we go from here?
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Two directions…
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
• cardioprotection• mechanisms of action• therapeutic potential
Genetic markers of cardiovascular risk / outcome
o
Increasing cardiac cGMP by pharmacologic means prevents cardiac hypertrophy
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
Chronic inhibition of cyclic GMP phosphodiesterase 5A (by Viagra) prevents and reverses cardiac hypertrophy.
Takimoto E et al. Nat Med 11: 214 - 22 (2005)
The cardiac GC transgene prevents functional deterioration in dystrophic hearts
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
mdx
mdx/GC+/0
PNAS 105:7028-7033 (2008)
The cardiac GC transgene and sildenafil have similar cardioprotective effects
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
PNAS 105:7028-7033 (2008)
Perfused working heart preperations with acute increase in cardiac mechanical stress by isoproterenol infusion
Cardioprotection via action on mitochondria?
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
From: Das A. et al. Am. J. Physiol. 296: H1236 (2009)
Sildenafil and MPTP opening (1)
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
[3H]‐DOG
PTP closed
PTP open
[3H]‐DOG‐6P
cardiomyocyte
(Burelle & al., unpublished
data)
Mitochondrial permeability
transition
pore opening
(MPTP)
RPP(mm Hg x bp
m)
Time(min)
Control
mdx
1 µM Norepinephrine
(Marcil et al. JMCC 2006)
LFI ReperfusionNormoxia
[3H]‐DOG
*mdx
+ Sil
*
Sildenafil and MPTP opening (2)
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
(Burelle & al., unpublished
data)
Index of membrane integrityLD
H re
leas
e (m
U*g
ww
*RPP
-1) * *
PTP opening
index
mdx
+ SilCtrl mdx
* *
([3 H]‐DOG ratio)
mdx
+ SilCtrl mdx
Two directions…
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
• cardioprotection• mechanisms of action• therapeutic potential
Genetic markers of cardiovascular risk / outcome
Phenotypic variation in young healthy adults
Cardioprotective effects of cyclic GMP: lessons from animal genetic models
50 60 70 80 90 100
110
120
130
140
0
5
10
15
LVM/BSA
Perc
enta
ge
0
500
1000
1500
2000
2500
3000
0
10
20
30
Plasma NT-ANP
perc
enta
ge(- 1 SD)
66.4 ± 7.6(+ 1 SD) 119 ± 8
(- 1 SD) 224 ± 49
(- 1 SD) 2220 ± 300
Institut de recherches cliniques de Montréalhttp://www.ircm.qc.ca
Acknowledgements Students and fellows:
• Sandra Masciotra• Isabelle Boutin-Ganache• Ahmad Zahabi• Emmanuelle Souzeau• Bastien Llamas
• Swapnil Sinha• Marie-Pier Scott-Boyer
Institut de recherches cliniques de Montréalhttp://www.ircm.qc.ca
Acknowledgements Collaborators:• U. of Burlington (Vt):
Edith Hendley
• U. of Montreal: Christine Des Rosiers Yan Burelle
• McGill University: Basil Petrov Jamie Engert
• Laval University: Éric Larose Philippe Pibarot
Funding: CIHR / NHLBI
VANCOUVER HYPERTENSIONSeptember 26-30, 2010VANCOUVER HYPERTENSION 2010September 26-30 2010
www.vancouverhypertension2010.com
Recommended