a pop to sis final

8/8/2019 A Pop to Sis Final

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Group 3 Section C2

Paraguya, Lanisa

Parias, Orlando IIPasajol, Margarita

Pascua, Vanessa


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To define Apoptosis

To differentiate apoptosis from necrosis

To determine the different cellular features

of both apoptosis and necrosis

To discuss the role of apoptosis in

embryogenesis, development and

differentiation of tissues, AIDS, Cancer and

immune defense

To discuss the different laboratory indices

that will define cells undergoing apoptosis


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a form of cell death designed to eliminate

unwanted host cells through activation of

coordinated, internally programmed series of

affected by a dedicated set of gene products.

Occurs under normal physiological condition

Can be induced by pathological conditions


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Hypoxia

Defective Energy (ATP) Production

Physical Agents and Drugs

Free Radicals

Infectious Agents

Immunological ReactionsGenetic Derangements

Nutritional Imbalance


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`Apoptosis (programmed cell death), isa normal component of the development

and health of multi-cellular organisms while

Necrosis (traumatic cell death) isuncontrolled cell death leads to lysis of

cells, inflammatory responses and,

potentially, to serious health problems.


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Causes regression of anatomical structures in fetal

development

Eliminates self-recognizing lymphocyte clones inimmunologic processes

Prevents overpopulation in continuously renewing

tissues

Maintains the balance of cellularity in the responseof the tissues to hormones

Deletes mutant cells or those with DNA damage

Eliminates cells infected with viruses


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APOPTOSIS Vs Death of single cells

Cytoplasmic blebbing

Chromatin condensation

Cell shrinkage Lysosomes and other

cytoplasmic organelles intact

Nuclear DNA breaks intofragments

Rapid phagocytosis of

apoptotic bodies bymacrophages and adjacentcells

No inflammatory response

NECROSIS Death of many cells

Plasma membranedisruption

Nuclear swelling and lysis Cell swelling

Lysosomal breakdown

Cell lysis and disintegration

Phagocytosis by

macrophage Often cause a damaging

inflammatory response insurrounding tissues


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Defining features Apoptosis Necrosis

Physiologic/pathologic features

Cellular role Usually normal Abnormal, accidental

Process Active, energy-dependent

Passive, results from

lack/loss of energy

Distribution Dispersed, affectsindividual cells

Contiguous,

simultaneous, andmassive affects in

damaged tissue areas

Triggers 100s of physiologic

and noxious stimuli

Sudden transfer of

energy, specifictoxins, or ATP

depletion

Induction Slow (hours),stochastic

Rapid (secs, mins)

Tissue inflammation Absent Present

Cell removal Rapid and discrete Slow


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Morphologic

featuresCellular membranes Integrity preserved,

blebbing of intactplasma membrane

Loss of integrity, with

spilling of cellconstituents

Cell volume Decreased, as well asthe formation of

small, fragmentedapoptotic bodies or

inclusions

Increased

Organelle structure Late preservation,with exception ofnuclear condensation

and fragmentation

Swelling of nucleus

and other organelles

Chromatin Discrete, organizedcondensation,

margination and

fragmentation (e.g.

pyknotic nuclei)

Pattern conserved


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Biochemical and

molecular featuresMitochondrial permeabilitytransition

Moderate Severe

Mitochondrial membranepotential (delta psi-m)

Transient loss Permanent loss

Requirement fro ATP Yes No

Membrane phospholipidasymmetry

Exteriorization of

phosphatidylserine from

inner to outer leaflet of

plasma membrane

Unchanged

Cell pH Acidification Unchanged

DNA cleavage Initial specific large

cleavage products of 300,then 50, kbp, followed by

internucleosomal cleavage

leading to DNA ladder

pattern of 180 bp unit

repeats

Random DNA cleavage

Caspase dependence Yes No


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The Extrinsic

or Death

ReceptorPathway

The Intrinsic or

Mitochondrial

Pathway


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There are 4 key processes:

1. Induction

2. Activation3. Execution

4. Removal of dead cells


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Triggered by transmembrane/external signals

or ligands:

Pro-apoptotic factors (Death signals) FasL TNF-

TRAIL

Anti-apoptotic factors Growth factors

Cytokines

Hormones


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Components:

Death Ligands- FasL, TNF, TRAIL

Death receptors e.g. Fas (CD95),

TNF-R1, TRAIL-R1

Adapter protein e.g. Fas-

Associated Death Domain (FADD)Caspases


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Cysteinyl-Aspartate Specific Proteases

Exist within the cell as inactive pro-forms or

zymogens

have been termed "executioner" proteins

Responsible for the cleavage of the key

cellular proteins that leads to morphologic

changes observed in cells undergoing

apoptosis


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Initiator CaspasesCaspases -2, -8, -9

and -10

Activated inresponse to deathsignal

Possess long pro-domains (CARDdomain)

Activate effectorcaspases

Effector CaspasesCaspases -3, -6 and -7

H

ave short pro-domains

Executioner ofapoptosis

Their action leads

to morphologicalfeatures such asDNA fragmentation


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1. Triggered by internal signals (pro-apoptotic)

such as: Growth factor deprivation

DNA damage Increased levels of reactive oxygen species

2. Regulated by Mitochodrial Outer Membrane

Permeabilization (MOMP)

3. Release of Cytochrome C


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Activation or inactivation of an

inner mitochondrial permeability transition

pore, which is involved in the regulation of

matrix Ca2+

, pH, and voltage. Some Bcl-2 family proteins can induce (pro-

apoptotic members) or inhibit (anti-

apoptotic members) the release

of cytochrome c into the cytosol which, oncethere, activates caspase-9 and caspase-3,

leading to apoptosis.


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` Differentiation of fingers and toes in a developing

human embryo occurs because cells between the

fingers apoptose; the result is that the digits are

separate.

` The effect of lack of programmed cell death (Specifically apoptosis) on

the toes of a human. A mutation caused the middle two toes to remainconnected.


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` During menstruation

` Development of an organ or tissue is often

preceded by the extensive division anddifferentiation of a particular cell, the resultant

mass is then "pruned" into the correct form by

apoptosis


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HIV Invades CD T Cells

CD T Cells dies


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IMMUNEDEFENSE

Immune defense isthe coordinated,

complicated interplay

of cellular

mechanisms andantibodies to fight

disease-causing

agents, including

viruses, bacteria, andother types of

infection.

APOPTOSIS

Apoptosis plays a keyand essential role in

the education of

immune cells in the

thymus and the bonemarrow, where

autoreactive cells are

eliminated, thereby

establishing toleranceto self tissues.


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The immune response to a foreign invader involves the proliferationof lymphocytes T and/or B cells. When their job is done, they

must be removed leaving only a small population of memory cells.

This is done by apoptosis.

Very rarely humans are encountered with genetic defects in

apoptosis.T

he most common one is a mutation in the gene for Fas,but mutations in the gene for FasL or even one of the caspases are

occasionally seen. In all cases, the genetic problem

produces autoimmune lymphoproliferative syndrome or ALPS.

Features: an accumulation of lymphocytes in the lymph nodes and

spleen greatly enlarging them.

The appearance of clones that are autoreactive; that is, attack

"self" components producing such autoimmune disorders.

the appearance of lymphoma a cancerous clone of lymphocytes.


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Associated with dysregulated apoptosis

Apoptosis elimnates damage cells

Damage mutation Cancer

Many cancer cells are defective in apoptoticpressure


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Histologic Examination

Tissues stained with H and E

Apoptotic cells

Fluorescent probes Mark apoptotic events in various ways

DNA strand breaks in situ

Change in mitochondria membrane potential


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Annexin V assay

Binds with high affinity to phosphatidylserine on the

outer surface of membrane

Cellular DNA fragmentation ELISA Labeling of target DNA using BrdU

Monoclonal antibody

Cell-death inducing reagent

Dna fragments (necrotic cells) Lying agent

y DNA fragments (apoptotic cells)

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