Vydehi veeramallaFinal yr pgDepartment of Biochemistry

CONTENTS

CELL SIGNALLING

TYPES OF SECOND MESSENGERS

CHARECTERISTICS OF SECOND MESSENGERS

HORMONES ACTING THROUGH CYCLIC AMP

MECHANISM OF ACTION OF CYCLIC AMP

EFFECTS OF CYCLIC AMP

HISTORYEarl Wilbur Sutherland Jr. – 1971 Nobel Prize in

Physiology or Medicine

Epinephrine – liver - glycogen to glucose – cAMP

INTRODUCTION

Cyclic AMP is a cyclic nucleotide

Chemically it is a 3’5’ adenosine monophosphate

It is synthesized in tissues from ATP under influence of ADENYLYL CYCLASE in presence of Mg ion

Degraded to 5’AMP in by Phosphodiesterase

It is a Second Messenger

cell signaling- 3 processes

A series of signaling events that mediate the response to each stimulus.

specific

amplified

regulated

coordinated.

receptors plasma membrane , cytoplasm or nucleus.

Second Messengers

cAMP pathway

cGMP pathway

IP3 / DAG pathway

Calcium as a second messenger

Eicosanoids

Second Messengers

General characteristics1) Low amounts in resting state

2) Regulated synthesis

3) Regulated destruction

4) Act through other proteins

hCGLHFSHLPH PTHCALCITON

IN

Epinephrine (β1,β2)NorepinephrineGlucagonCRHACTHMSH TSH

1.Somatostatin

2.Acetylcholine M2

3.Angiotensin II

4.Epinephrine α2

ATIVATE ADENYLYL CYCLASE

INHIBIT ADENYLYL CYCLASE

AVP/ADH

G Protein-Linked Receptors

G-PROTEIN COUPLED RECEPTOR

tes

Activation of G Proteins

AC

ADENYLYL CYCLASE

G PROTEIN ACTIVATES ADENYLYL CYCLASE

Cyclic AMP

PROTEIN KINASE A - ACTIVATION

EFFECTS OF CYCLIC AMP1. ALTERED GLYCOGEN METABOLISM BY ENZYME REGULATION

2. ALTERED GENE TRANSCRIPTION

3. HORMONE ESTRADIOL SECRETION

4. ALTERED ION TRANSPORT - HCL SECRETION IN STOMACH

5. WATER REABSORPTION BY ANTI DIURETIC HORMONE

6. CAFFEINE – PHOSPHODIESTERASE INHIBITORS

7. DRUGS – SALBUTAMOL , THEOPHYLLINE

ENZYME REGULATION

GSD VIII,IX GSD X

GENE TRANSCRIPTION

TRANSCRIPTION FACTOR COACTIVATOR

ESTRADIOL SECRETION

STOMACH - HCL SECRETION

HISTAMINE

KIDNEY - WATER REABSORPTION

ANTIDIURETIC HORMONE

PHOSPHODIESTERASE INHIBITORS

EPINEPHRINE NOREPINEPHRINE SALBUTAMOL

DRUGS

THEOPHYLLINEPDE

Summary

Cyclic amp is a mediator of hormone actionSecond messengerActivates protein kinase A

Causes glycogenolysis Causes lipolysisModulates TranscriptionActivates Hormone secretionIncreases gastric secretionRegulates cell permeability to water