Study of the role of the PGC-1β transcriptional coactivator

in white adipose tissue and its implication in the development of insulin resistance

Natàlia Enguix Elena

Laboratory of Metabolism and Obesity

Unit of Diabetes and Metabolism

Fatty acids

Fatty acids

Acyl-CoAs

Diacylglycerols

Ceramides

Insulin

IRS

PKC ATP

STOP

Thiazolidinediones

Adipogenesis

Mitochondrial Biogenesis Oxidative Metabolism

Fatty acid uptake Triglycerides accumulation

Lipid oxidation

White AdiposeTissue

Fatty Acid Oxidation

mtDNA replication/transcription

Oxphos System

NRF1/2

ERR

PGC-1

PGC-1

PGC-1

PGC-1

COLD EXPOSURE

EXERCISE

PPAR

Nucleus

TFAM

(Patti et al, PNAS 2003)

Skeletal Muscle

Decreased mitochondrial mass and function in diabetic patients is associated with low PGC-1 expression

White Adipose Tissue

(Bogacka et al, Diabetes 2005)

Mitochondrial Mass PGC-1 mRNA

No Diabetic Control

Placebo Pioglitazone

Diabetic

No Diabetic Control

Placebo Pioglitazone

Diabetic

Control

Diabetic Control

Diabetic

Expression of mitochondrial genes and mitochondrial biogenesis is not altered in WAT of PGC-1-FAT-KO mice

loxP loxP

1 2 3 4 5 6 7 8 9 10 11 12 13

1 2 3 6 7 8 9 10 11 12 13

+ aP2-Cre

Floxed allele

PGC-1-FAT-KO

0,0

0,5

1,0

1,5

a.u

.

mtDNA

wt ko 0

0,5

1

1,5

mR

NA

(a.

u.)

Gene Expression White Adipose Tissue

mR

NA

(a.

u.)

1.2

0.8

0.4

0

1.6

Kidney Liver Testis Spleen Muscle Thymus BAT WAT

Gene Expression Wildtype

PGC-1-FAT-KO

** **

Pardo et al. PLoS One (2011)

Rosiglitazone-induced mitochondrial biogenesis and function is independent of PGC-1

Rela

tive m

tDN

A c

onte

nt

mtDNA

Cont. Rosig

2.5

2.0

1.5

1.0

0.5

0

Citrate synthase

CS

activity

m

ol/m

g.m

in

Cont. Rosig

2.5

2.0

1.5

1.0

0.5

0

3.0

3.5

0

0.5

1.0

1.5

2.0

2.5

3.0

mR

NA

expre

ssio

n

(Rela

tive u

nits)

PGC-1

Wt FAT-KO COXII COXIV CYCS ATP5b CS ACO2 MCAD

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

mR

NA

expre

ssio

n

(Re

lative

units)

Wt Cont. FAT-KO Cont. Wt Rosig. FAT-KO Rosig.

Pardo et al. PLoS One (2011)

0

0,2

0,4

0,6

0,8

1

Pre Conf Post d0 d2 d4 d6 d8

mR

NA

(R

elat

ive

un

its)

Days during differentation

PGC-1β

PPARγ

Pref-1

0

0,2

0,4

0,6

0,8

1

1,2

1,4

mR

NA

(R

ela

tive

un

its)

PGC-1β ATGL

PGC-1β is highly expressed in mature white adipocytes

Pref-1

* **

*

0

0,5

1

1,5

2

2,5

NRF-2 NRF-1 ERRα ERRγ RIP140 PGC-1β

mR

NA

(R

ela

tive

un

its)

Wild type + Vehicle

Wild type + Rosiglitazone

Gene Expression

Generation of PGC-1β-FAT-KO mice

2 3 5 8 1 4 6 7 9 10 11 12

2 3 8 1 6 7 9 10 11 12

+ aP2Cre

Floxed allele

PGC-1β-FAT-KO

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

BAT iWAT Adipocytes Kidney Lungs Soleus Spleen Testis Thymus

mR

NA

(a.

u.)

PGC-1β Expression

Wildtype

PGC-1B-FAT-KO

Adipose tissues

** ** **

30ºC

Gene expression profiling in WAT of PGC-1β-FAT-KO mice

Microarray DNA

Wildtype (n=5)

Knockout (n=5)

PGC-1β regulates expression of genes involved in oxidative metabolism in white adipose tissue

0

0,2

0,4

0,6

0,8

1

1,2

1,4

NDUFAB1 NDUFB9 SDHB CytC1 CytCs Cox5a Cox5b Cox7a1 ATP5a1 ATP5o

mR

NA

(R

ela

tive

un

its)

Wild type

PGC-1β-FAT-KO

0

0,2

0,4

0,6

0,8

1

1,2

1,4

Aco2 Idh3a Idh3b MDH2 LDHB PGK1 Elovl6 Cpt1b Cidea Cideb

mR

NA

(R

ela

tive

un

its)

Wild type

PGC-1β-FAT-KO

* * *

** * *

* *

C I C II Cyt C C IV C V

OXPHOS

TCA Cycle Glycolysis Lipid Metabolism / Oxidation

* * *

** *

* **

*

*

Gene Expression White Adipose Tissue

Wild type PGC-1β-FAT-KO

Aconitase

ATPSynβ

NDUFB9

COX IV

SDHB

Cyt c

α-tubulin

PGC-1β-FAT-KO mice exhibit reduced levels of TCA cycle and OxPhos proteins and impaired oxidative capacity in white adipose tissue

White Adipose Tissue

0

0,05

0,1

0,15

0,2

μm

ole

/mg

/min

Citrate Synthase Activity

0

0,01

0,02

0,03

μm

ole

/mg

/min

Cytochrome Oxidase Activity

WT KO WT KO

* *

Rosiglitazone-induced mitochondrial gene expression and function is mediated by PGC-1β

0

1

2

3

4

CoxIV Cox8b Cox7a1 CytCs ATPSynB Aco2 CS Cpt1b

mR

NA

(a.

u.)

Gene Expression White Adipose Tissue

Wt + vehicle

KO + vehicle

Wt + Rosiglitazone

KO + Rosiglitazone**

** *

*

**

* * *

*

0

100

200

300

400

Vehicle Rosiglitazone

nm

ol/

mg·

min

Citrate Synthase Activity

*

0

1

2

3

4

5

Vehicle Rosiglitazone

a.u

.

mtDNA Content

Lack of PGC-1β in adipocytes does not induce whole body or tissue-specific insulin resistance

50

150

250

350

450

0 20 40 60 80 100 120

Glu

cose

(m

g/d

L)

Time (min)

Glucose Tolerance Test

Wt + Vehicle

KO + Vehicle

Wt + Rosiglitazone

KO + Rosiglitazone

0

50

100

150

0 20 40 60 80 100 120

Glu

cose

(m

g/d

L)

Time (min)

Insulin Tolerance Test

Conclusions

PGC-1β in white adipose tissue specifically regulates the expression of genes involved in mitochondrial energy production.

PGC-1β but not PGC-1α mediates the rosiglitazone-induced expression of mitochondrial genes and the oxidative capacity of white adipose tissue.

Full mitochondrial oxidative function is not required for the insulin-sensitizing effects of thiazolidinediones.

Thank You

Metabolism and Obesity Laboratory

PGC-1β regulates mitochondrial gene expression in 3T3-L1 adipocytes

0

1

2

3

4

mR

NA

(a.

u.)

PGC-1α

0

1

2

3

4

mR

NA

(a.

u.)

PGC-1β

0

2

4

6

mR

NA

(a.

u.)

CytCs

0

1

2

3

mR

NA

(a.

u.)

IDH3β

**

0

1

2

3

mR

NA

(a.

u.)

ATPSynβ

0

1

2

3

mR

NA

(a.

u.)

NDUFB9

siControl: siPGC-1α: siPGC-1β:

+ - - - + - - - - + - + - + - + - - + + - - + +

+ - - - + - - - - + - + - + - + - - + + - - + +

DMSO Rosiglitazone DMSO Rosiglitazone

siControl: siPGC-1α: siPGC-1β:

+ - - - + - - - - + - + - + - + - - + + - - + +

+ - - - + - - - - + - + - + - + - - + + - - + +

DMSO Rosiglitazone DMSO Rosiglitazone

0

1

2

3

4

5

6

7

Re

lati

ve U

nit

s

Oxygen Consumption Rate 3T3L1 Adipocytes

P=0.09

P=0.11

P=0.16

siControl: siPGC-1α: siPGC-1β:

+ - - - + - - - - + - + - + - + - - + + - - + +

+ - - - + - - - - + - + - + - + - - + + - - + +

Basal CCCP

DMSO

Rosiglitazone

Gene expression

** ** ** **

** ** **

**

** **

* **

** **

** ** ** **

* **

** **

** **