Lecture 14 Flashcards
(24 cards)
What are the 5 gene therapy research examples?
- Whole cell gene therapy
- Gene therapy for immunocontraception
- CRISPR and its applications
- Clinical trials gene therapy for occular disease
- Molecular therapies for neuromuscular disorders
Define Gene Therapy
A collection of techniques for correcting a defective gene problem
What is the most common approach to gene therapy?
A normal gene copy is inserted into a non-specific location within the genome to replace a non-functioning gene
What are the 4 viral vectors in gene therapy?
- Adenoviruses
- Adeno-associated viruses
- Herpes Simplex Virus
- Retroviruses
Characteristics of Adenoviruses
- Double-stranded DNA
- Cause o Respiratory infections
o Intestinal infections
o Eye infections - Causes the ‘common cold’
Characteristics of Adeno-Associated viruses
- Small
- Single-stranded DNA viruses
- Insert their genetic material at a specific point on chromosome 19
Characteristics of Herpes Simplex Virus
- double stranded DNA
- Infect neurons
- HSV1 = cold sore
Characteristics of Retroviruses
- Create double-stranded DNA copies of their RNA genomes
- Integrate copies into chromosomes of host cells
- e.g. HIV
How does gene therapy of non-viral delivery work?
DNA is transferred by physical means
- direct injection
- electroporation
- gene gun
e.g. o Liposomal DNA delivery
o Whole cell transplantation
o (Mammalian expression) plasmids
Characteristics of Duchenne Muscular Dystrophy
- X-linked recessive
- Result of a non-functioning dystrophin gene
- Patients wheelchair bound by 12y.o.
- Death (cardiac/resp. failure) in third decade of life
Characteristics of the dystrophin gene
2.4 Mb long
79 exons long
Encodes multiple isoforms
What is the full length of the dystrophin protein?
427kDa
What are the genetics of DMD?
Nonsense or frameshift mutations causing premature termination of translation = truncation
What are the 5 genetic therapy approaches for DMD?
- Mini Dystrophin Gene Delivery
- Transcriptional Read Through
- Exon Skipping
- Homologue Induction
- Cell based whole gene replacement
What is the Mini dystrophin gene delivery process?
- smaller dystrophin genes based on Becker examples delivered via plasmid or viral vectors
What is the transcriptional Read Through process?
Some antibiotics will cause ribosomes to ignore STOP codons
What is the Homologue Induction process?
A dystrophin analogue called utrophin has a promoter which may allow selective upregulation
What is the Cell based whole gene replacement process?
Donor muscle precursor cells (myoblasts) which have the function dystrophin gene is transplanted by myoblast transfer therapy (MTT)
Define Myoblast Transfer Therapy
The direct injection of dystrophin expressing donor myoblasts into dystrophic muscle
–> provides a cell based gene rescue
What do the hinge regions do on a dystrophin gene?
Provide flexibility
What does the rod domain do on the dystrophin gene?
Provide stretchability
The rod and hinge regions on dystrophin gene do what together?
Protect from the force of contraction and relaxation
If you get a mutation in the actin binding regions or cysteine rich regions, which dystrophy would you get?
DMD
If a mutation is found in the hinge regions or C terminal domain, which dystrophy would you get?
BMD
