Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
33 Cards in this Set
- Front
- Back
Why would one use gene therapy?
|
To compensate for a loss of function mutation
Replace/inactivate a dominant negative mutation provide a pharmocological effect to counteract the results of a mutation |
|
What are the two forms of gene therapy?
|
Somatic-manipulating gene expression in cells of patient, but not passing that manipulation on to the next generation
Germline-modifying germline cells, NOT AN OPTION |
|
Three approaches to gene therapy?
|
Ex Vivo
In Situ In Vivo |
|
What is Ex Vivo
|
cells removed from body, incubated with vector containing the gene of interest, and cells returned to body
as in stem cells with IL-2 |
|
In Situ?
|
vector placed directly into affected tissues(a type of in vivo)
|
|
In Vivo?
|
vector injected directly to tissue or ECF--taken up selectively by target cells
|
|
Transduction?
|
Viral infxn of normal cells
|
|
Nonviral introduction of target gene?
|
Plasmid
|
|
What genetic element must the target gene have in order to be produced in the target cell?
|
Promoter/Enhancer regions (aka regulatory elements)
confers: amount of expression, tissue specificity, and timing of expression |
|
What is necessary for the target gene to be integrated into the host genome?
|
Viral DNA that surrounds the target sequence and regulatory elements?
|
|
What part of the virus facilitates uptake?
|
The viral coat
|
|
What is necessary for a plasmid induction of target genes?
|
Lipid encapsulation or electroporation
(not as effective as viruses) |
|
Retrovirus advantages
|
Can enter nearly ever cell in target pop.
rendered incapable of replication nontoxic to cells low number of copies integrate stably into host cells |
|
Retrovirus disadvantage
|
can only infect actively diving cells(tumors)
only hold up to 8 Kb insert potential for insertional mutagenesis |
|
Lentivirus adv.?
|
Enters all cells via nuclear pore
Neurotropic, and will infect stem cells nontoxic Accepts a large sized insert Can be either integrating or autosomal |
|
Lentivirus Disadvantages
|
potential for insertional mutagenesis
deemed safe, but only used in one clinical trial for HIV disabled herpes can only transduce 8-10 kb inserts |
|
Adenovirus Adv.?
|
infect wide variety of cells
8-10 kb size when gutted, can hold up to 22 kb inserts!!!! Episomal, thus no inseritional mutagenesis very efficient, high titre |
|
Adenovirus Dis.?
|
transient expression in dividing
potential for strong immunological response-->student was killed due to explosive immunological response |
|
Adeno-Associated viruses Adv.?
|
no known adverse effects in humans, why its the "darling"
infects all cells(dividing and nondividing), thus neurotropic exists primary as an episome long expression time |
|
Adeno-Associated disadvantages?
|
very small insertion size
host response to viral vector could cause loss of virus producing cells. |
|
Name 4 non viral vectors?
|
Naked DNA
DNA in liposomes DNA protein conjugates Artificial chromosomes |
|
What are advantages and disadvantages of NON viral vectors
|
A: no infectious risk, and no limit on insert size
D: low efficiency of infection, degraded by host |
|
Risks of Gene therapy?
|
To great an immune response to vector
Transferred DNA may integrate into patients DNA, and cause disruption of tumor supressor activites or upregulate protooncogenes...also could disrupt and essential gene |
|
Name two cases of gene therapy success?
|
Hemophilia B-clotting factor 9 was transduced via adeno-associated virus
Angina-VEGF-2 transduced into patients to stimulate growth of new blood vessels (8/12 experienced decreased drop in angina) |
|
What is SCID? Why is it relevant to gene therapy?
|
severe combined immunodeficiency
no B or T cell immunity in the past, only able to due bone marrow transplant with gene therapy-->isolated bone marrow stem cells, inserted correct gene, returned stem cells to patient 9/11 developed normal T and B cell fxn 3 patients developed luekemia like symptoms due to insertional mutagenesis |
|
What is the basis of gene therapy for cancer?
|
Transfer of therapeutic genes to a tumor mass or the peritumoral tissue
--includes transfer of suicide genes to induce cell death following admin. of a prodrug |
|
What is Suicide Gene Therapy?
|
NOT GENE REPLACEMENT!
introduce a new gene that converts a nontoxic prodrug into a lethal drug compound |
|
What are the specific examples mentioned in class regarding suicide genes? Drugs? Enzymes?
|
In a tumor cell:
Ganciclovir=prodrug Vector=carries Thymidine Kinase Gene TK phosphoryates Ganc. converting it to its active form, facilitates cell death |
|
Parkinson's symptoms?
|
tremor of hands, arms, legs or jaw
rigidity of limbs, trunk bradykinesia-slowness of mov't postural instability/impaired balance, coordination classic stooped posture and shuffling gate |
|
Parkinson's causes?
|
Neuronal death, esp. in Substantia Nigra(lots of dopaminergic receptors)
Substantia Nigra deterioration-->striatum-->Subthalamic nuclei become overactive-->loss of inhibition of motor output |
|
What protein is genetically mutated in Parkinson's?
|
alpha-Synuclein--leads to aggregate formation known as Lewy bodies
|
|
What environmental factors contribute to Parkinson's?
|
Well water, pesticides, herbicides
synthetic narcotic MPTP |
|
How can we use gene therapy to treat our future Parkinson's Patients
|
Introduce the enzyme GAD-glutamic acid decarboxylase-to synthesize GABA(inhibitory NT).
use adeno associated virus transduced subthalamic nuclei become INHIBITORY vs. excitatory, stimulating motor activity(relieve inhibition of motor output) |