cell signaling and bile acid metabolism

6
Bernard Bouscarel, Ph.D., D.Sc. Associate Professor of Biochemistry and Molecular Biology and of Medicine Director, Digestive Diseases Center Director, Molecular Medicine Program [email protected] 202-994-2114

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Bernard Bouscarel, Ph.D., D.Sc. Associate Professor of Biochemistry and Molecular Biology and of Medicine Director, Digestive Diseases Center Director, Molecular Medicine Program [email protected] 202-994-2114. 1988. Bile acids, hormone AA responses and cirrhosis/diabetes. - PowerPoint PPT Presentation

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Page 1: Cell signaling and bile acid metabolism

Bernard Bouscarel, Ph.D., D.Sc.

Associate Professor of Biochemistry and Molecular Biology

and of Medicine Director, Digestive Diseases Center

Director, Molecular Medicine Program

 [email protected] 202-994-2114

Page 2: Cell signaling and bile acid metabolism

Cell signaling and bile acid metabolism1988

1992

Chemotherapy and TopoI inhibitor

1994

UDCA as a chemotherapeutic

agent2000

Bile acid and chemoprevention

2006

UDCA and cholestatic liver

diseases

Elucidation of hepatic hormonal and AA response

Bile acids and skin fibroblast signaling

Bile acids and fibroblast proliferation

Bile acids and hepatic cell

proliferation

Bile acids, hormone AA responses and cirrhosis/diabetes

Relationship between fibroblasts and HSC

Hepatic fibrosis prevention

Bile acids & Taurine transport

Bile acids and hepatic signaling

Page 3: Cell signaling and bile acid metabolism

C M C M

Total PKC

P-PKC

-actin

CTL CDCA

(1)

(1)

(2.13)

(4.45)

PKC phosphorylation

glucagon

Bile Acid

DAG PIP2IP3

Ca2+

? P

P P

?

??

GR

P ?

?P

PSDAG

Ca2+

PKC

Catalytic domain

Pseudosubstrate

PLC

GS

AC

ATP

cAMP

Cholestasis: Bile acids/ hormonal response

Background:

Hypothesis:

Methods:PKCtranslocation

10’

6’

0’

Co-localization of GR & PKC

0’ 20’

Green: GR, Red: PKC, Yellow; merge

GR phosphorylation

CTL CDCA(25M)

PL

WB

(1) (3.0)

Bile acids are responsible for the decreased hepatic glucagon responsiveness in cholestasis through a mechanism involving PKC and GR phosphorylation.

Genomics, proteomics, and pharmacologic approaches to identify the relevant amino acids phosphorylated by bile acids leading to activation of PKC and inhibition of GR cellular response.

Le et al. Am J Physiol. 2006Ikegami et al. Endocrinology. 2006Krilov et al. (in preparation)

GR: glucagon receptorAC: adenylyl cyclasePLC: phospholipase C

Cholestatic and cirrhotic patients (50-80%) display: glucose intolerance decreased gluconeogenic response to glucagon hepatic resistance to glucagon attenuation of glucagon-induced cAMP production

Bile acids attenuate glucagon-induced cAMP production through a mechanism involving PKC

Page 4: Cell signaling and bile acid metabolism

Fibrosis: Bile acids/ fibroproliferation

Background:

Hypothesis:

Methods:

Co-Inv. and Collaborators:Drs. Rojkind, Ceryak and Kashanchi

Drs. Lin, Latham and Piper

Chronic liver disease and cirrhosis in particular, is the 12th leading cause of death in US.

Fibrosis is a hallmark of cirrhosis

Hepatic stellate cells (HSC) are key in the development of liver fibrosis.

ILK

Cox2

Growth arrest/death

Proliferation survival

Normal HSC

Cox2

ILK

Fibrotic HSC

Growth arrest/death Proliferation

survival

Zhang et al. Hepatology. 2006Meng et al. Am J Physiol. 2006Meng & Bouscarel (submitted)

HSC

CTL Chol

ILKCox-2

CDCACTL

Normal

CirrhosisFXR= farnesoid X receptorPKC= protein kinase CP38= p38 MAPKILK= integlin-liked kinase

PI3K

AKT

PKCFXR

ILKCox2P38

Proliferation

Bile acids

BA stimulate COX-2-mediated cell cycle arrest/death. In fibrosis, this signal is blunted through increased ILK expression/ activation fibroproliferation.

Isolation of HSC and Human skin fibroblasts (HSF) from control and patients with acute/chronic cholestasis.

Pharmacologic, genomic, and proteomic methods to identify key determinants of fibroproliferation.

Liver

Page 5: Cell signaling and bile acid metabolism

Cancer: Bile acids/ topoisomerase I inhibitors

Background:

Purpose/ Methods:

Compare the effect of various agents, BA, H+-pump inhibitor, PLC, CPT-11 analogs, CPT-11…. on:

•Tumor cell metastasis•Survival rate•Cell proliferation, apoptosis, cell cycle factors•Tumor gene expression

Colorectal cancer (CRC) is a leading cause of cancer-related death.

Bile acids play an important role in the etiology of CRC.

Certain bile acids (UDCA) may have chemotherapeutic properties against CRC.

CPT-11 (Irinotecan, Camptostar) is one of the leading anti-cancer drugs for CRC therapy.

Liver

Spleen

Kidney

Heart

LungSpleenFluorescence intensity

Liver

2 weeks later

I.P. injection

CPT-11

UDCA

drinking

MC-26 cells transfected with GFP

Spleen

Liver

BALB/c mice

Spleen

Liver

BALB/c mice

Ikegami et al. Cancer Res. 2002Ikegami et al. Mol Cancer Ther. 2006Ikegami et al. (submitted)

Hypothesis:

UDCA enhances the antitumor chemotherapeutic

action of CPT-11.

Page 6: Cell signaling and bile acid metabolism

www.gwu.edu/~ddc/

Bernard Bouscarel, PI

Jiamping Meng, Senior Scientist

Teruo Miyazaki, Post Doc

Maryam Alrashid, 5th year IBS student

Lada Krilov, 4th year IBS student

Amy Nguyen, 2nd year IBS student

Helen Johnston, 1st year IBS student (Rotation)

Nara Lee, Undergraduate student

Ivy Akid, Undergraduate student