Question

Describe two diseases that occur as a result of cytoskeletal defects and explain how the protein defects result in the disease symptoms. (Tip: Write a brief description of each disease. Discuss the symptoms that occur as a result of the disease. Also make sure you mention which cytoskeleton element is defective and how this translates to the actual symptoms of the disease).

Answer 1

The eukaryotic cells contain Plasmamembrane and Cytoplasm.Cytoplasam contain cellular Organells which are mainly:

a) Nucleus

b) Endoplasmic Reticulum which has rough and smooth ER,

c) Golgiapparatus,

d) Mitochondria,

e)Ribosomes,

f)Lysosomes,

g) Peroxisomes all presented in cytoplasms termed as Cytosol,

The cytoplasm organised by the CYTOSKELETON and is highly dynamic.

The cytoskeleton has three types of protein filaments Crisscrossing the eukaryotic cell.

these three filaments are mainly Actin filaments, microtubles and intermediate filaments, all types provide the structure and organisation of to the cytoplasm and shape to the Cells.

The Motion and position of organells and cytoskeletal elements are under tight regulation at certain stages of life,

The interaction between the cytoskeleton and organelles are non covalent, reversible and extra cellular signals.

List of Diseases caused by Cytoskeleton defects:

1)Autosomal Dominant Cerebral Ataxia

2)Amyotrophic Lateral Sclerosis,

3)Asphyxiating Thoracic Dysplasia etc.

1)Autosomal dominant Cerebral Ataxia:

- The most common type of Hereditary Ataxia are autosomal dominant ataxia called SCA ( spine  cerebellar ataxia),

- The sca types are depending on the typical clinical manefestations and the gene location,

- Out of 36 types, the SCA 1,2,3,6,7,12, and 17 have been reported in India,

- the symptoms are mainly Slow eye Movement distinguished by visual symptoms progressing to Blindness due to Pigmentary Macaulay Dystrophy,

2) Amyotrophic Lateral sclerosis:

- ALS is a Motor Neuron Disease occurs due to unknown Reasons,

- main defect is the anterior horn cells from which the nerves of the spinal cord originate and the brain stem neurons or Bulbar neurons gradually destroyed, along with degeneration of pyramidal fibers, Intrestingly all , all sensations are normal,

- The symptoms mainly starts with muscle wasting in the hands and legs and movements become less,

- Gradually, climbing stairs and even wearing footwear also become difficult,

- they become stiff,

- 3 to 4 yrs of Disease completely Bed ridden.

- In Neurological Language, Signs and symptoms of both upper and lower Motor neuron dysfunction are seen on examination.

- the reason behind that reactive astrogliosis and microglial activation may play a vital role.

Note: The Cytokeratines are group of 20 proteins make up cytoskeleton intermediate filaments of epithelial cells,

Clinically Useful cytokeratines are:

a) Tissue polypeptide Antigen (TPA),

b) Tissue polypeptide Specific antigen,

c) cytokeratin 19 filaments,

d) Squamous cell carcinoma Antig