Pancreatic β-Cell
Nucleus Envelop
Nucleol
Chromatin
Lysosome
Mitochondria
Glucose
Glucose
Glucokinase
Glucokinase Gl
Glucose Transporter
T
t
Nonmaturated Vesicles
Glucokinase (sensor of glucose level)
Maturated Vesicles
Closing the K+ATP Channel
Endoplasmic Reticulum
Depolarization of the Membrane
Golgi Apparatus
Exocytosis
Opening the Ca+ Channel
secretory vesicle
Normal
102
secretory vesicle
~
ProInsulin
Insulin
ProAmylin
Amylin
< 102
Pro-diabetes
Amylin Deposition is a Hallmark of Type-2 Diabetes
in Humans
Diabetes 56:1324-1332 (2007)
HUMAN PANCREAS
20 µm
20
Amylin
Transmissible Spongiform
Encephalopathies
Dementia,
Alzheimer’s Disease
Parkinson’s
Disease
Type-2
Diabetes
Hyperamylinemia, Amylin Oligomerization,
& the Risk of Cardio-Cerebrovascular Diseases
β‐Cell Dysfunction & β
Cell Dysfunction &
Apoptosis
B
BLOOD
Pancreatic β‐Cell
β
AMYLIN
OLIGOMERIZATION
HYPERGLYCEMIA
(INSULINOGENIC DRUGS)
HYPERAMYLINEMIA
Florin Despa
HYPERINSULINEMIA
Department of Pharmacology
University of California, Davis
Relevance to Our Mission
This research project is relevant to understanding, preventing, and, possibly, treating
diabetes complications in two ways:
1. It uncovers an early pathogenic mechanism linking age-related metabolic
disorders with diabetic brain injury, dementia, and CVD;
2. It identifies hyperamylinemia as a feasible therapeutic target to reduce
accumulation of proteinaceous debris in the CV and CN systems, and thus to limit/
delay diabetes complications.
Outline of Research in My Laboratory
1. Mechanisms of amylin oligomer formation and accumulation:
a. understanding the etiology of hyperamylinemia;
b testing the circulating amylin oligomer hypothesis.
b.
hypothesis
2. Amylin oligomer-induced cardiac dysfunction:
a. primary structural defect induced by oligomers in myocytes;
b. hypertrophy, remodeling;
c. oxidative and inflammatory stress.
3. Role of oligomeric amylin in diabetic brain damage and dementia:
a. interaction & co-localization of amylin with Aβ;
b. amylin oligomer-mediated inflammatory and oxidative damage.
4. Curbing amylin deposition to delay/reduce the CVD risk:
a. pro-fibrinolytic molecules limit amylin attachment to sarcolemma
and reduce
red ce ROS prod
production
ction in cardiac myocytes.
m oc tes
Collaborators
• Kaleena
K l
JJackson
k
• Kathy Guglielmino
• Brian Koch
•
•
•
•
•
•
•
•
•
Sanda Despa
Bruce Hammock
Peter J Havel
Anne Knowlton
Donald Bers
Heinrich Taegtmeyer (UTHS)
Keneth B. Margulies (U Penn)
Donald Steiner (U Chicago)
Simon Xie (Stanford)
•
•
•
•
Heike Wulff
Elva Diaz
Gustavo Barisone
Dave Speca
AD Center
• Charles DeCarli
• Lee-way Jin
Funds: AHA, NSF, UCD AD Center, Vision Grant - UC Davis
Cardiotoxicity of Hyperamylinemia
(RATIONALE)
Lean
Non-Failing
g Hearts
Lean, Non-diabetes
Failing Hearts
Amylin
Oligomers
Obese/Overweight
Non-Failing
g Hearts
Obese/Overweight
Failing Hearts
Type-2 Diabetes
Failing Hearts
Amylin
Oligomers
distinct amylin oligomer
size distributions
Amylin Oligomers Accumulate in Heart
FAILING
OCTAMER
TETRAMER
TRIMER
DIMER
NON-FAILING
DM-HF
F
0
OW/OB
B-HF
100
**
Larger Amylin Oligomers
500
**
400
*
300
200
100
0
DM-HF
16-MER
200
OB-HF
OW/O
trimer
10
kDa
300
OW/OB
B-NF
15
**
O
OW/OB
-NF
tetramer
tet
a e
400
L-HF
octamer
**
L-HF
50
500
L-NF
OW/OB-HF
AmylinTTrimers
L-NF
L NF
L-NF
Amylin
n Level (% C
Control)
Anti-Amylin Antibody
Amylin Trimers (% C
Control)
Failing vs. Non-failing
Despa S, …, Despa F. Circ Res. 2012;110:598
Cardiac Amylin Deposition in Humans with Type-2 Diabetes
HEART
PANCREAS
HEART
20 µm
20 µm
HEART
Co
ongo Red Staining
Antii-Amylin A
Antibody
20 µm
20 µm
HEART
Control
HEART
20 µm
20 µm
Despa S, …, Despa F. Circ Res. 2012;110:598
Selection of Human Brain Samples
Type-2 Diabetes +
CD and/or AD
Amylin Accumulation
Late-onset AD
no diabetes
Amylin Accumulation
Age-matched, lean (?),
non-diabetics, without AD
?
Amylin Deposition in the Brain of Patients with Dementia
A
20 µm
B
20 X
D
20 X
20 µm
C
20 µm
20 X
20 µm
E
20 X
20 µm
20 X
F
20 X
20 µm
G
20 µm
PANCREAS
20 X
Amylin co-localizes with Aβ
B
A
10 µm
C
10 µm
E
D
10 µm
T2D-AD Group
10 µm
F
10 µm
10 µm
40 X
Not All Amylin Species are Amyloidogenic !
Human Amylin (amyloidogenic)
KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY
Q
Rat Amylin (non-amyloidogenic)
KCNTATCATQRLANFLVRSSNNLGPVLPPTNVGSNTY
Q
Despa et al., Biol. Phys. (2008)
Pancreas
Heart
PancreasHeart
25
15
10
kDa
HIP rats
UCD-T2DM rats
Animal Models
Human Amylin
pancreas
HIP rat
Rat Amylin
Pre Diabetes
Pre-Diabetes
180
160
140
120
100
H IP
B lo o d G lu c o s e
m g /d l)
(m
non-fasted
UCD-T2DM rat
200
U C D -T 2 D M
pancreas
Summary (1)
Circulating Amylin Oligomers
?

mitochondrial
dynamics
 Ca transients
attachment to endothelial
cells
 ROS
 RAGE
CaMKII/HDAC
activation
ti ti
Calcineurin/NFAT
activation
ti ti
 Hypertrophic signaling
 SERCA expression
i
?
 NF-κB
 TNF-α;
TNF α;  IL-6;
IL 6;

Altere
ed glucose
e/ lipid hom
meostasis; Other factors
attachment to sarcolemma
IL 10
IL-10
?
 Diastolic [Ca]i
Slower Ca transient
relaxation
Diastolic
dysfunction
 Ca transients
Systolic dysfunction
inflammation
Oligomeric amylin accelerates
diabetic HF !
0
HIIP
40
6000
4000
2000
0
HIIP
Maximum Rate of
P
Pressure
Ri
Rise
80
8000
RIIP
*
dP/dtmax (mm
mHg/s)
120
RIIP
End
d Systolic P (mmHg)
Cardiac Accumulation of Oligomeric Amylin Induces
Contractile Dysfunction in Pre-diabetic HIP Rats
Left-Ventricular
End Systolic Pressure
Maximum Rate of
Pressure Fall
0
HIP
2000
collab. with A. Knowlton (UC Davis)
6
4
2
0
HIP
4000
8
RIP
*
End Diasttolic P (mm
mHg)
6000
RIP
-dP/dtm
min (mmHg//s)
Left-Ventricular
End Diastolic Pressure
Cerebral Accumulation of Oligomeric Amylin Induces
Behavioral Changes in HIP Rats
collab. with S. Xie (Stanford)
Therapeutics:
Th
Reversing/Preventing
g
g Amylin
y
Oligomer-Induced
g
Injury
j y
Patent US20070031955
“Compositions and Methods for Refolding of Denaturated Proteins”
(sold to Maroon Biotech).
Circulating Amylin Oligomers
↑ EET
EETs
↓ sEH
EH
Altered glucose/ liipid homeo
ostasis; Otther factors
s
attachment to sarcolemma

 Ca transients
APAU
mitochondrial
dynamics
 ROS
CaMKII/HDAC
C
MKII/HDAC
activation
Calcineurin/NFAT
C
l i
i /NFAT
activation
 Hypertrophic signaling
 SERCA expression
 Diastolic [[Ca]]i
Slower Ca transient
relaxation
 Ca transients
Systolic dysfunction
Diastolic
dysfunction
Summary
Hyperamylinemia and consequent amylin oligomerization are an
early pathogenic mechanism linking age-related metabolic
disorders with diabetic brain injury, dementia, and CVD.
Hyperamylinemia is a feasible therapeutic target to reduce
accumulation of proteinaceous debris in the CV and CN systems,
and thus to limit/ delay diabetes complications.