Killer Actin

Question 1

What cellular processes rely on actin dynamics?

Answer 1

Cell morphology → Determines shape and structure.
Cell polarity → Organizes directional transport and movement.
Endocytosis → Regulates vesicle formation.
Intracellular trafficking → Actin serves as a transport scaffold.
Contractility & motility → Required for crawling movement.
Cell division → Forms the contractile ring in cytokinesis.
Cell death → Actin aggregation is associated with apoptosis.

Question 2

How does actin aggregation contribute to neurodegeneration?

Answer 2

Abnormal actin filament accumulation disrupts cellular integrity.
Interferes with trafficking of essential proteins.
Leads to oxidative stress and mitochondrial dysfunction, a hallmark of Alzheimer’s.

Question 3

Why is yeast used as a model system to study actin aggregation?

Answer 3

Yeast have a single actin gene (ACT1) → Simplifies genetic studies.
Easy to manipulate genetically, allowing precise experiments.
Yeast undergo mitochondrial apoptosis, similar to mammalian cells.
Unicellular but naturally form clusters, mimicking tissue environments.

Question 4

What environmental factor triggers actin aggregation in yeast?

Answer 4

Nutrient depletion → Yeast cells aggregate actin and undergo apoptosis.

Question 5

What is the mitochondrial theory of ageing?

Answer 5

Ageing results from accumulated mitochondrial damage, reducing cellular function.

Question 7

What diseases have been linked to free radical damage?

Answer 7

Cancer
Arthritis
Alzheimer’s
Parkinson’s
Diabetes.

Question 8

What happens to mitochondria as yeast age?

Answer 8

Decline in mitochondrial performance.
Increased oxidative stress, contributing to cellular deterioration.

Question 9

What is Latrunculin A?

Answer 9

A natural compound isolated from the red sea sponge Latrunculia magnificans.

Question 10

How does Latrunculin A work?

Answer 10

Binds G-actin in a 1:1 ratio, preventing polymerization.
Locks ATP in the actin-binding cleft, disrupting filament formation.

Question 11

How does Latrunculin A affect actin aggregation?

Answer 11

Prevents actin aggregation, blocking apoptosis caused by nutrient depletion

Question 12

What is the sequence of events in the killer actin cycle?

Answer 12

1️ Nutrient depletion → Cellular stress increases.
2️ Actin aggregation begins → Disrupts cellular processes.
3️ Cell ageing & apoptosis occur → Organismal loss of function.