Regulation of IGF and IGF binding protein gene expression by Regulation of IGF and IGF binding protein gene expression by

nutrition and aquaculture related stressors: nutrition and aquaculture related stressors:

Implications in fish growth and stress assessment Implications in fish growth and stress assessment

Cunming Duan

University of Michigan, Ann Arbor, MI

Genotype Environmental factors

Growth

Food

Growth hormone (GH) transgenic animals

IGFs

GH

Extra-hepatic tissues(somatic, gonadal)

Liver

Brain

Environment

IGFs

The growth-promoting action of GH in postnatal stages is mediated The growth-promoting action of GH in postnatal stages is mediated by Insulin-like growth factors (IGFs)by Insulin-like growth factors (IGFs)

"Somatomedin Hypothesis""Somatomedin Hypothesis"

"Endocrine""Endocrine"

"Paracrine, autocrine""Paracrine, autocrine"

+

+

-

Duan (1997) Am. Zool.

pituitary

Insulin-like Growth Factor-1

B-domain

C-domain

A-domain

D-domain

G

P

E

T

L

GA

EL V D A L Q F

V

GD

R

G

F

Y

F

N

K

P

TG

YGSSSRRA

PQ

TG

I

V

D

E

C

F

R

S

DL

RR

LE

M

YC

A

P

L

K

P

AKSA

C

C

C

C

GrowthDevelopment ReproductionAging

IGF1R

IGF-1

Insulin-like Growth Factor (IGF) Signaling:

IGF-2

The IGF signaling is a evolutionarily conserved pathway that plays fundamental roles in growth control

The IGF signaling is a evolutionarily conserved pathway that plays fundamental roles in growth control

IGF-IR deficientIGF-IR deficientControlControl

Schlueter et al., FASEB J, 2006

Woods et al., N Engl J Med, 1996

Abuzzahab et al., N Engl J Med, 2003

Walenkamp et al., JCEM, 2005

Sutter et al., Science, 2007

Liu et al., Cell, 1993 Baker et al., Cell, 1993

IGFs

GH

Extra-hepatic tissues(somatic, gonadal)

Liver

Brain

Environment

IGFs

IGFs mediate GH actions in postnatal stagesIGFs mediate GH actions in postnatal stages

"Endocrine""Endocrine"

"Paracrine, autocrine""Paracrine, autocrine"

+

+

-pituitary

J. Nutrition, 1998

_

+ elevated levels- reduced levels? unknown

IGFs

GHIGFs

Extra-hepatic tissue growth(muscle, bone, gonad etc.)

Liver

Brain

Environment

Wood, A.W., Duan, C., and Bern, H.A. (2005). Insulin-like growth factor signaling in fish. Int. Rev. Cyto. 243: 215-285

StarvationUndernourishment Malnourishment

IGF-1 expression is also regulated by nutritional factors

pituitary

IGFs

GHIGFs

Extra-hepatic tissue growth(muscle, bone, gonad etc.)

Liver

Brain

Environment

IGF-1 expression is also regulated by nutritional factors

StarvationUndernourishment Malnourishment

Wood, A.W., Duan, C., and Bern, H.A. (2005). Insulin-like growth factor signaling in fish. Int. Rev. Cyto. 243: 215-285

pituitary

The hepatic expression IGF-1 is under the dual regulation The hepatic expression IGF-1 is under the dual regulation of nutrients and GHof nutrients and GH

IGFs

GHIGFs

Extra-hepatic tissues

Liver

Brain

Environment

Nutrients

•The nutritional regulation of the GH-IGF-I axis is an interface between nutrients and hormones acting in concert to control animal growth.

•This interface is conserved throughout vertebrate evolution.

pituitary

IGFs are bound to IGF binding proteins (IGFBP) in IGFs are bound to IGF binding proteins (IGFBP) in extracellular fluids extracellular fluids

BP

IGF

ALS

BP

IGF IGF

•Regulate the biological activities of IGFs by controlling their access to the IGF-1 receptors on target cells.

•Prolong the half-life of IGFs.

IGFBP-1

Hypoxia

.1

1

10

100 *

Hypox

ia

Norm

oxia

IGF

BP

-1 m

RN

A/ß

-act

in m

RN

A (

fold

)

Normoxia

Maures and Duan, 2002, Endocrinology

Kelley et al., 2002, J. Endocrinology

IGFBP-1 is induced by stressors

Low O2 Normal O2

IGFBP-1 is a hypoxia-inducible gene in zebrafish fish embryos and larvae

Kajimura et al. PNAS, 2005

96 hpf

Kajimura et al., PNAS (2005); Kajimura and Duan Fish Biol. (2007)

(1) Induction of IGFBP-1

IGF receptor

(2) Reduced “available” IGF

(3) Reduced IGF signaling

(4) Suppression of IGF actions

(5) Growth retardation Developmental delay

BP

-1

BP

-1

BP

-1

BP

-1

Catabolic or stressful conditions

IGFBP-1 is a metabolically controlled molecular switch IGFBP-1 is a metabolically controlled molecular switch that inhibits IGF actions under catabolic states that inhibits IGF actions under catabolic states

Fasting induces and re-feeding reduces IGFBP-1 gene expression in young zebrafish

Kamei, Lu, Jiao, et al., PLoS One, 2008

Experimental Design

2 month-old fish were fed with various rations (1, 3, and 9% of body weight) for 4 weeks

1-month old juvenile fish were fed with different diets. They are standard diet followed with:

high vs. low carbohydrate;high vs. low protein;

high vs. low fat;high vs. low vitamin contents

4 fish were sacrificed and their IGFBP-1a/-1b mRNA levels were measured by qRT-PCR and normalized by β-actin mRNA levels

At each sampling time, 20 fish were randomly picked up to measure their body length and body weight at each time point

40-50 fish in each experimental group

Each experiment has two parallel groups

Effects of different feeding rations on growth and IGFBP-1a and -1b gene expressions

a

fg

c

b

a

ded

cbc

ef fg fgh fgh

gh gh gh gh

Feng Q et al. unpublished data

abcd

abcdabcd

abcd

abcd

abcd

bcd

abc

abcd

abcd

abcd

a

ab

abcd

dcd

IGFBP-1a

bcd

bcd

bcde

bcde

bcd

bcde

bcde

de

abc

abcd

bcd

bcde

a

ab

cde

e

IGFBP-1b

Feng Q et al. unpublished data

Effect of diet protein levels on growth and IGFBP-1 gene expression

a

a

b

bccd

d

d ee ef

efg

efg

g

Feng et al. unpublished data

ab

cde

aaa

bcbc

bcd

bcd

cde

cdede

e

IGFBP-1a

aab

ab abab

abcabc

ababc

cdede

de e

IGFBP-1b

Feng et al. unpublished data

abcd

bcde

bcdefdef

aab

abc abcd

bcdef

cdef

ef

eff

IGFBP-1a

abc

cd

a

ab

abc ab

abc abc bcd

cdcd

cd d

IGFBP-1b

Feng et al. unpublished data

Conclusions and Discussion

• The hepatic IGF-I expression is under the regulation of GH and nutritional states. This dual regulation of IGF-I represents an interface between nutrients and hormones acting in concert to control animal growth.

• The GH-IGF-I axis plays central roles in fish growth regulation.

• These results suggest that the levels of IGF-1 and IGFBP-1 expression (or their ratio) are useful indicators of growth and may be useful tools in nutrient utilization and stress assessment.

• IGFs in blood and other extracellular fluids are present in complexes with several IGFBPs.

• The levels of IGFBP-1 expression is reversely correlated with growth.

• IGFBP-1 is highly induced by food deprivation, malnutrition, stress, and hypoxia.

Hypoxia followed by re-oxygenation accelerates growth and developmental rates

Catch-up growth

Kamei et al. (2011) Development

Supported by grants from:National Science FoundationNational Institutes of Health

National Heart, Lung and Blood Institute , NIH