Subcellular level of Injury Flashcards
What are the major functions of lysosomes?
- Turn over of cellular constituents
- Nutrient sensing via mTORC1 recruitment to promote anabolism
- Calcium storage
- Calcium signalling
How do lysosomes turn over cellular constituents?
- Endocytosis, phagocytosis, autophagy
What is calcium signalling important for?
- Lysosomal acidification
- Fusion with other organelles
- Membrane trafficking and repair
- Autophagy
How can indigestible material interact with lysosomes?
- Exogenous or endogenous materials may persist in lysosomes as residual bodies
What is the outcome of endogenous material interacting with lysosomes?
- Lipofuscin
What is lipofuscin? What can lipofuscin be made up of?
- Auto fluorescent lipopigment
- Highly cross-linked, undegradable protein that aggregates lipids, carbohydrates, and metals
What is lipofuscin known as?
- The wear-and-tear pigment
Why is lipofuscin formed?
- ROS and oxidative stress
How can oxidative stress and aging be detected due to lipofuscin?
- The gradual accumulation of lipofuscin in neurons, retinal pigment, epithelium, cardiac myocytes, and muscles cells
What are the major components of lysosomes? (3)
- Luminal proteins
- Integral membrane proteins
- Lysosomal-associated proteins (LAMPs)
What is the purpose of luminal proteins in lysosomes?
- This is where acid hydrolases or their activators for enzymes reside
What fits in the category of integral membrane proteins in lysosomes?
- Structural amino acids and lipid transporters
- Ion-channels
- Trafficking and fusion machinery
- Membrane catabolic enzymes
- Vesicular ATPase to sense acidity
What is LSD? What is it classified by?
- Lysosomal Storage Disease
- Inborn errors of metabolism
What are two “kinds” of LSDs?
- Caused by enzyme defects
- Caused by defects in enzyme activates or associated proteins
What are the most common forms of LSDs?
- Fabry
- Gaucher
- Metachromatic leukodystrophy
- Pompe
- What do Fabry and Gaucher disorders have in common?
- Characterized by the accumulation of glycolipids
What is metachromatic leukodystrophy?
- Destroyed white matter in the CNS
What is Pompe characterized by? Why does this happen?
- A glycogen storage disease
- Enzymes (GAA-acid alpha-glucosidase) are not breaking down glycogen, and it builds up