jaemyoung suh salk institute/hhmi la jolla, ca icdm nov.9, 2012icdm2012.diabetes.or.kr/slide/s3 jae...
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A New NR-FGF Axis: Regulation of Feast and Famine
Jaemyoung SuhSalk Institute/HHMI
La Jolla, CA
ICDM Nov.9, 2012
Feast and Famine
- Feast/famine cycles are a recurrent environmental stressor
- The ability to withstand periods of limited/excess nutrientavailability is critical to animal survival
Cinti S Am J Physiol Endocrinol Metab 2009;297:E977-E986
Adipose tissues:
Central to the feast/famine response
Visceral white adipose tissue
Subcutaneous white adipose tissue
Brown fat
Adipose tissues are dynamic and
possess wide developmental potential
Feast(Adipose expansion)
Famine(Adipose contraction)
Adipose development and remodeling–
coordination of multiple cell types
Adipose tissue remodeling - adaptive response to energy stress
PPARg
- Adipose tissues expand and contract during feast/famine cycles� a process called “remodeling”
- Remodeling is a complex process that requires coordinated changes within adipocytes, immune cells, surrounding vasculature, and the extracellular matrix
- Adaptive remodeling is dynamic and critical for maintaining metabolic homeostasis
- The mechanisms underlying remodeling are poorly understood
Fibroblast growth factors
Fatty acids Bile acids Vitamin D
PPARα/RXR FXR/RXR VDR/RXR
Nuclear
receptor
Growth factor
expression
Physiological
response
FGF21 FGF15/19 FGF23
Energy
homeostasis
Bile acid
homeostasis
Phosphate / Ca+
homeostasis
The NR-FGF axis
Ligands
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Fed HFD Fast Fed HFD Fast
Relative expression
Relative expression
FGF1A in Vis WAT FGF1B in Vis WAT
FGF1 in adipose tissue is regulated by
nutritional cues
**
**
Wild type visceral fat
Chow Diet High-Fat Diet
FGF1
FGF1 protein is induced by high fat diet in
adipose tissue
Adipose tissue subcompartments –
adipocytes and stromal cells
Collagenase
Adipocytes
(float)
Stromal –Vascular-Fraction
(sink)
. . .. . . . . ..
FGF1 is expressed predominantly
in visceral adipocytes
Whole Fat Subcutan. Visceral
SC adip. SVF adip. SVF
Fgf1
ERK1/2
Visceral fat depots are linked to metabolic disease and
has more active remodeling capacity than subcutaneous fat
Vis
Fibroblast growth factors
PPARαPPARα
FXRFXRVDRVDR
NR regulation?NR regulation?
Metabolism?Metabolism?
Normal
Normal
FGF1:a “boring” FGF
30
34
38
42
46
50
0 2 4 6 8 10 12 14 16 18 20 22 24
No change in body weight gain in FGF1
KO mice on a HFD
Time (weeks)
Body weight (grams)
Still boring>>.?
WT
KO
100
200
300
400
0 15 30 45 60 75 90
60
80
100
120
140
160
0 15 30 45 60 75 90
Time (min)
Glucose (mg/dl)
Glucose (mg/dl)
Time (min)
**
**
* **
Increased insulin resistance in FGF1 KO
mice on HFD
Glucose Tolerance Test Insulin Tolerance Test
WT
KO
0
4
8
12
16
0
5
10
15
20
25
Increased peripheral and hepatic insulin
resistance in FGF1 KO mice on a HFD
WT KO WT KO
IS-GDR HGP (% suppression)
GIR (mg/kg/m
in)
GIR (mg/kg/m
in)
*
*
Skeletal muscle Liver
WT
KO
Visceral adipose tissue fails to expand in
FGF1 KO mice on a HFD
0
2
4
6
8
% BW
Control HFD
0
1
2
3
4**
**
% BW
Control HFD
Liver Visceral fat
WT
KO
Increased liver fat accumulation in FGF1
KO mice on a HFD
KO
WT KO
Non-uniform size distribution in FGF1 KO
visceral adipocytes
WT
KO
-1
-0.5
0
0.5
1
1.5
2
2.5
3
Log (KO/W
T (frequency)
Small Medium Large
Bin (square µm area)
Increased fibrosis in visceral adipose tissue of
FGF1 KO mice on a HFD
Masson’s trichrome stain – collagen stains blue
KO
KOWT
Impaired vascularity in visceral adipose of
FGF1 KO mice on a HFD
WT KO
Visceral adipose tissue can’t properly expand in response to HFD in FGF1 KO mice;;. But, can it contract?
Heart perfusion of fluorescent spheres – vascular space in red, nuclei in blue
KO
36 weeks high fat diet
6 weekschow diet
Modern-day yoyo diet
WT
KO
Further impairment of FGF KO visceral
adipose tissue upon HFD withdrawal
Failure of FGF1 KO visceral WAT to properly contract upon HFD withdrawal
WT KO
Fat necrosis in FGF1 KO mice after
removal of HFD
Fatty
acids
Bile acids Vitamin D
NR PPARα/RXR FXR/RXR VDR/RXR
Nuclear
receptor
Growth factor
expression
Physiological
response
FGF1 FGF21 FGF15/19 FGF23
Fat
remodeling
Energy
homeostasis
Bile acid
homeostasis
NR-FGF Axis
?
?
?
Phosphate / Ca+
homeostasis
0
4
8
12
16
0
4
8
12
16
Regulation of FGF1 by PPARγ and TZDs
Luc/LacZ
PPARα
Ligand - + - + - +
PPARγ PPARδ PPARα
Ligand - + - + - +
PPARγ PPARδ
FGF1A FGF1B
**
**
*
0.00
0.05
0.10
0.15
0.20
0.25
PPARγ binds to the FGF1 promoter
FGF1
Input chromatin (%)
36B4
** Adip.
WT KO
FGF1
ERK1/2
SVF
WT KO
FGF2
FGF1 levels reduced in
PPARγ adipose KO mice
IgG
PPARγ
A new NR-FGF axis
Acknowledgements
Ron Evans Hans JonkerMichael DownesAnn AtkinsMaryam AhmadianRuth Yu
Jerry OlefskyPingping Li
Future directions
• Some major questions ;
- Why is only visceral fat affected by loss of FGF1?
- Are adipocytes solely responsible for the whole body KO phenotype?
- What are the target cells of FGF1 action?
- Is there any therapeutic relevance for FGF1 in treating metabolic disease?
Fasting glucose (mg/dl)
104
108
112
116
120
124
1.0 1.5 2.0
Fasting blood glucose
FGF1 (fold induction)
*
FGF1 (fold induction)
0.0
0.5
1.0
1.5
2.0
Induction of FGF1 by TZD
ctrl TZD
FGF1 link to insulin sensitization
- Is there a human connection?
FGF1 gain-of-function studies- exploring therapeutic possibilities
• Pharmacological
- Parental delivery of recombinant FGF1 protein into animal models of obesity/diabetes.
• Genetic
- Tissue-specific transgenic overexpression of FGF1
- Viral overexpression of FGF1
Experimental approaches
Anti-diabeticInsulin sensitization
TZD
PPARγ (master regulator)
Cardiovascular toxicityWeight gainEdemaLiver toxicityBone loss
FGF1
ActosAvandia
$ 4 bn
>100 target genes
FGF1 : therapeutic possiblities ?
?Time (days)
Recombinant FGF1 has potent glucose lowering effects in diabetic ob/ob mice
?
Adipose stem cell(CD34, CD29, Sca-1, CD24,
PPARγ, Zfp423)
1
2
3
Mature adipocyte(aP2, Glut4, Perilipin,
LPL, Leptin, Resistin)
4
Mural cell(SMA, NG2, PDGFRβ)
Endothelial cell(PECAM-1, VE-Cadherin,
VEGFR2,Tie2)
Hypertropic adipocyte(TNF-α, ROS, FFA)
Dying adipocyte(Perilipin-)
The adipocyte life cycle
DIET &NUTRITION
DRUGS
AGING
DEVELOPMENT
DISEASE
Biology of adipose tissues
Feast and Famine
VDR
PPARg
-Feast/famine cycles have occurred throughout time
-The ability to withstand periods of limited/excess nutrientavailability is a critical aspect of survival
Why would alleles predisposing to obesity
exist in natural populations?
“Thrifty allele hypothesis”
James V. Neel, M.D.,Ph.D.
(1960s)
“Genes associated with common modern diseases like diabetes,
hypertension and obesity are part of the human gene pool,
because they helped our early ancestors survive when calories
and salt were less abundant.”
Fatty
acids
Fatty
acids
Bile acids Vitamin D
PPARγ/RXR PPARα/RXR FXR/RXR VDR/RXR
Nuclear
receptor
Growth factor
expression
Physiological
response
FGF1 FGF21 FGF15/19 FGF23
Fat
remodeling
Energy
homeostasis
Bile acid
homeostasis
Phosphate
and calcium
homeostasis
A new member of the FGF-NR Axis
Acknowledgements
FGF1 is NOT boring!
+
BlastocystZygote
Ectoderm
Endoderm
Mesoderm
Development: Lineage RestrictionBrain Skin
Liver Pancreas
Lung ThyroidGI Tract
Bone Muscle
Blood Kidney HeartPluripotent
Stem Cells( )
Topological distribution of adipose
organs – developmentally regulated
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