Cell Communication - Weeblyeggersbiologypage.weebly.com/uploads/3/7/2/8/... · LE 11-2 Exchange of mating factors Mating Receptor a α α factor a α Yeast cell, a factor mating type

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 11

Cell Communication


Overview: The Cellular Conversation

•  Cell-to-cell communication is essential for multicellular organisms

•  Biologists have discovered some universal mechanisms of cellular regulation


External signals are converted into responses within the cell

•  A signal-transduction pathway is a series of steps by which a signal on a cell’s surface is converted into a specific cellular response

•  Signal transduction pathways convert signals on a cell’s surface into internal cellular responses

•  Pathway similarities suggest that ancestral signaling molecules evolved in prokaryotes and have since been adopted by eukaryotes

LE 11-2 Exchange of mating factors

Mating

Receptor

a α

α factor

a α

a factor Yeast cell, mating type a

Yeast cell, mating type α

a/α

New a/α cell


Local and Long-Distance Signaling

•  Cells in a multicellular organisms communicate by chemical messengers

•  Animal and plant cells have cell junctions that directly connect the cytoplasm of adjacent cells

•  In local signaling, animal cells may communicate by direct contact

LE 11-3 Plasma membranes

Gap junctions between animal cells

Cell junctions

Cell-cell recognition

Plasmodesmata between plant cells


•  In many other cases, animal cells communicate using local regulators, messenger molecules that travel only short distances

•  In long-distance signaling, plants and animals use chemicals called hormones

LE 11-4

Paracrine signaling

Local regulator diffuses through extracellular fluid

Secretory vesicle

Secreting cell

Target cell

Local signaling

Electrical signal along nerve cell triggers release of neurotransmitter

Neurotransmitter diffuses across synapse

Endocrine cell Blood vessel

Long-distance signaling

Hormone travels in bloodstream to target cells

Synaptic signaling

Target cell is stimulated

Hormonal signaling

Target cell


The Three Stages of Cell Signaling: A Preview

•  Earl W. Sutherland discovered how the hormone epinephrine acts on cells

•  Sutherland suggested that cells receiving signals went through three processes:

–  Reception

–  Transduction

–  Response

LE 11-5_3

EXTRACELLULAR FLUID

Reception

Plasma membrane

Transduction

CYTOPLASM

Receptor

Signal molecule

Relay molecules in a signal transduction pathway

Response

Activation of cellular response


1. Reception: A signal molecule binds to a receptor protein, causing it to change shape

•  The binding between a signal molecule (ligand) and receptor is highly specific

•  A conformational change in a receptor is often the initial transduction of the signal

•  Most signal receptors are plasma membrane proteins

LE 11-6 EXTRACELLULAR FLUID

Plasma membrane

The steroid hormone testosterone passes through the plasma membrane.

Testosterone binds to a receptor protein in the cytoplasm, activating it.

The hormone- receptor complex enters the nucleus and binds to specific genes.

The bound protein stimulates the transcription of the gene into mRNA.

The mRNA is translated into a specific protein.

CYTOPLASM

NUCLEUS

DNA

Hormone (testosterone)

Receptor protein

Hormone- receptor complex

mRNA

New protein


•  An ion channel receptor acts as a gate when the receptor changes shape

•  When a signal molecule binds as a ligand to the receptor, the gate allows specific ions, such as Na+ or Ca2+, through a channel in the receptor

Ligand Gated Ion Channels

LE 11-7c

Signal molecule (ligand)

Gate closed Ions

Ligand-gated ion channel receptor

Plasma membrane

Gate closed

Gate open

Cellular response


2. Transduction: A series of molecular interactions relay signals from receptors to target molecules in the cell

•  Transduction usually involves multiple steps

•  Multistep reaction pathways can amplify a signal: A few molecules can produce a large cellular response

•  Multistep pathways provide more opportunities for coordination and regulation


Signal Transduction Pathways

•  The molecules that relay a signal from receptor to response are mostly proteins

•  Like falling dominoes, the receptor activates another protein, which activates another, and so on, until the protein producing the response is activated

•  At each step, the signal is transduced into a different form, usually a conformational change


Protein Phosphorylation and Dephosphorylation

•  In many pathways, the signal is transmitted by a cascade of protein phosphorylations

•  Phosphatase enzymes remove the phosphates, kinases add them.

•  This phosphorylation and dephosphorylation system acts as a molecular switch, turning activities on and off

LE 11-8 Signal molecule

Activated relay molecule

Receptor

Inactive protein kinase

1 Active protein kinase

1



2



3

ADP

Inactive protein

Active protein

Cellular response

ATP

PP P i

ADP ATP

PP P i

ADP ATP

PP P i

P

P

P


Cyclic AMP

• Cyclic AMP (cAMP) is one of the most widely used second messengers

•  Adenylyl cyclase, an enzyme in the plasma membrane, converts ATP to cAMP in response to an extracellular signal

LE 11-13

Binding of epinephrine to G-protein-linked receptor (1 molecule)

Reception

Transduction

Inactive G protein

Active G protein (102 molecules)

Inactive adenylyl cyclase Active adenylyl cyclase (102)

ATP Cyclic AMP (104)

Inactive protein kinase A

Inactive phosphorylase kinase

Active protein kinase A (104)

Active phosphorylase kinase (105)

Active glycogen phosphorylase (106) Inactive glycogen phosphorylase

Glycogen Response

Glucose-1-phosphate (108 molecules)


3. Response: Cell signaling leads to regulation of cytoplasmic activities or transcription

•  The cell’s response to an extracellular signal is sometimes called the “output response”

•  Ultimately, a signal transduction pathway leads to regulation of one or more cellular activities

•  The response may occur in the cytoplasm or may involve action in the nucleus

•  Many pathways regulate the activity of enzymes, turn genes on or off.

LE 11-14

Reception Growth factor

Receptor

Phosphorylation cascade

Transduction

CYTOPLASM

Inactive transcription factor

Active transcription factor

P Response

Gene

mRNA

DNA

NUCLEUS


The Specificity of Cell Signaling

•  Different kinds of cells have different collections of proteins

•  These differences in proteins give each kind of cell specificity in detecting and responding to signals

•  The response of a cell to a signal depends on the cell’s particular collection of proteins

•  Insulin Signaling animation http://vcell.ndsu.nodak.edu/animations/insulinsignaling/movie-flash.htm


Termination of the Signal

•  Inactivation mechanisms are an essential aspect of cell signaling

•  When signal molecules leave the receptor, the receptor reverts to its inactive state

•  Cell Communication Animationshttp://www.dnalc.org/resources/3d/cellsignals.html

•  http://www.youtube.com/watch?v=U6uHotlXvPo


Pathway Mapping of EGF Signaling in a Cancer Model EGF

EGFR

EGFR

HER3

HER2

INTE

GRIN

CADH

ERIN

Caveolin

Catenin-δ

EPS15

CBL

GAB1

SRC

RhoGEF5

SHC

P85

CRKL

STAT3

ERK2

P110

RAS

RAF

SOS GRB2

MEK

Catenin-α1

PDK AKT

PLC-γ

α-Actinin

RhoGAP

Vinculin

F-Actin

PKC-δ

FAK

PXN

Cortactin

TFR

PXN

FAK

HGS

MET

MET

GSK3-α, β

EPH

Recs

ERK1 Y19

Y289

Y689

Y1422(β4)

Y132

Y251

Y657

Y88

Y198

Y207

Y204 Y187

Y1680

Y20

Y418

Y605

Y1197 Y1234

Y397

Y397 Y421

Y576

Y279, 216

Y446

Y464

Y822

Y118

Y22

Y329/334

Y1248

Y705

Y1253

Y1110

Y576

Y1207(β4)

Y783(β1)

Y998

Y318

Y1069

Y88

Y1016

Y869

Y349/350

Y280

Y771

Y313

Y1139

Y783

Y467

Y371

Y291

Y221

Y1092

Y704

Y228

Y6

Y248

Y280

Y213

Y217

Y14 Y849

Y772

Y614

Y655

Y455

Y602 Y596

Y779

Y334

Y118

Y296

SHB

Y201 Y333

Y355 Y423

Y1172

Y1328 Y797

Y570 Y427

Y575

Y628 Y608

Y594 Y1127

Cdc42

Ack p38 MAPK Y182

Y857

Y858 Y267

Crk

Y136

Y570

Y1510(β4)

DAPP1

Y139 Y154 Y141

Nck Y105


RAS

RAF-1

MEK1/2

ERK1/2

ELK-1, C-MYC

MNK

SHC

PLC

γ1 C

BL

SR

C GRB2

SOS

CRK

PI3K

PDK1

AKT GSK3

mTOR

JAK

STAT1

STAT3

GA

B-1

p38 MAPK

LAB

/LAT

IRS

1

IRS

2

CDC42

ACK1

JNK

C-JUN

GRB10 FAK

SPTAN1

SPRY2

SCF38

Proliferation

NF-κβ, ATF2, MNK

α α

β β

Insulin Receptor

SH

C

GR

B2

Crk

Fox0

Apoptosis

p90RSK

UV/Stress BCR

GR

B2

CB

L

Lipid Raft Aggregation

SY

K

PLCγ2

SOS VAV1

Protein Synthesis

EGFR/HER2

C-MYC

Integrins

SR

C

Pax

illin

FAK

Cell Adhesion Migration

GAB-1

γ β

Cytokine Receptor TCR GPCR

Endocytosis

p53

TfR

CSK

Ezr

in

Actin Cytoskeleton Migration

Amino Acid Transport

Rac

STAT3

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Cell Communication - Weeblyeggersbiologypage.weebly.com/uploads/3/7/2/8/... · LE 11-2 Exchange of mating factors Mating Receptor a α α factor a α Yeast cell, a factor mating type