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Novel Genome-Editing Tools to Model and Correct Primary Immunodeficiencies.

Ott de Bruin LM, Volpi S, Musunuru K - Front Immunol (2015)

Bottom Line: With this treatment, severe complications may result due to integration within oncogenes.With these genome-editing tools a correct copy can be inserted in a precisely targeted "safe harbor." They can also be used to correct pathogenic mutations in situ and to develop cellular or animal models needed to study the pathogenic effects of specific genetic defects found in immunodeficient patients.This review discusses the advantages and disadvantages of these endonucleases in gene correction and modeling with an emphasis on CRISPR/Cas9, which offers the most promise due to its efficacy and versatility.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, Boston Children's Hospital, Harvard Medical School , Boston, MA , USA ; Department of Pediatric Immunology, Wilhelmina Children's Hospital, University Medical Center Utrecht , Utrecht , Netherlands.

ABSTRACT
Severe combined immunodeficiency (SCID) and other severe non-SCID primary immunodeficiencies (non-SCID PID) can be treated by allogeneic hematopoietic stem cell (HSC) transplantation, but when histocompatibility leukocyte antigen-matched donors are lacking, this can be a high-risk procedure. Correcting the patient's own HSCs with gene therapy offers an attractive alternative. Gene therapies currently being used in clinical settings insert a functional copy of the entire gene by means of a viral vector. With this treatment, severe complications may result due to integration within oncogenes. A promising alternative is the use of endonucleases such as ZFNs, TALENs, and CRISPR/Cas9 to introduce a double-stranded break in the DNA and thus induce homology-directed repair. With these genome-editing tools a correct copy can be inserted in a precisely targeted "safe harbor." They can also be used to correct pathogenic mutations in situ and to develop cellular or animal models needed to study the pathogenic effects of specific genetic defects found in immunodeficient patients. This review discusses the advantages and disadvantages of these endonucleases in gene correction and modeling with an emphasis on CRISPR/Cas9, which offers the most promise due to its efficacy and versatility.

No MeSH data available.


Related in: MedlinePlus

A double-stranded break (DSB) in the DNA can be repaired through the process of homologous recombination (HDR) or through the error-prone process of non-homologous end-joining (NHEJ). In HDR, a template is used to correct the DSB. HDR can be used to precisely introduce a gene or part of a gene or even a point mutation, whereas NHEJ can result in insertions and/or deletions (indels) around the DSB. An indel can lead to a frameshift and an early stop codon.
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Figure 1: A double-stranded break (DSB) in the DNA can be repaired through the process of homologous recombination (HDR) or through the error-prone process of non-homologous end-joining (NHEJ). In HDR, a template is used to correct the DSB. HDR can be used to precisely introduce a gene or part of a gene or even a point mutation, whereas NHEJ can result in insertions and/or deletions (indels) around the DSB. An indel can lead to a frameshift and an early stop codon.

Mentions: While SIN-RV and SIN-LV vectors demonstrate a safer integration site profile, greater control over vector site integration is still desired. Engineered endonucleases that introduce double-stranded breaks (DSB) at specific sequences in the genomic DNA offer much more control over the integration site of viral vectors. Cells repair a DSB either through the error-prone process of non-homologous end-joining (NHEJ) or through homology-directed repair (HDR) in which a highly homologous template, either a sister chromatid or an exogenous double-stranded or single-stranded DNA template, is copied accurately. HDR can be used to either insert a gene into a specific “safe harbor” or to replace a defective gene in situ (Figure 1). “Safe harbors” are regions in genomic DNA that do not contain oncogenes and that can be disrupted without adverse consequences. One such safe harbor is the adeno-associated virus integration site 1 (AAVS1) locus. In order to insert a functional copy of the PID-causing gene into a specific locus, such as AAVS1, one can use an engineered endonuclease to introduce a DSB at the site and a DNA repair template containing the gene flanked by two homology arms that match the AAVS1 sequence (36–39).


Novel Genome-Editing Tools to Model and Correct Primary Immunodeficiencies.

Ott de Bruin LM, Volpi S, Musunuru K - Front Immunol (2015)

A double-stranded break (DSB) in the DNA can be repaired through the process of homologous recombination (HDR) or through the error-prone process of non-homologous end-joining (NHEJ). In HDR, a template is used to correct the DSB. HDR can be used to precisely introduce a gene or part of a gene or even a point mutation, whereas NHEJ can result in insertions and/or deletions (indels) around the DSB. An indel can lead to a frameshift and an early stop codon.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440404&req=5

Figure 1: A double-stranded break (DSB) in the DNA can be repaired through the process of homologous recombination (HDR) or through the error-prone process of non-homologous end-joining (NHEJ). In HDR, a template is used to correct the DSB. HDR can be used to precisely introduce a gene or part of a gene or even a point mutation, whereas NHEJ can result in insertions and/or deletions (indels) around the DSB. An indel can lead to a frameshift and an early stop codon.
Mentions: While SIN-RV and SIN-LV vectors demonstrate a safer integration site profile, greater control over vector site integration is still desired. Engineered endonucleases that introduce double-stranded breaks (DSB) at specific sequences in the genomic DNA offer much more control over the integration site of viral vectors. Cells repair a DSB either through the error-prone process of non-homologous end-joining (NHEJ) or through homology-directed repair (HDR) in which a highly homologous template, either a sister chromatid or an exogenous double-stranded or single-stranded DNA template, is copied accurately. HDR can be used to either insert a gene into a specific “safe harbor” or to replace a defective gene in situ (Figure 1). “Safe harbors” are regions in genomic DNA that do not contain oncogenes and that can be disrupted without adverse consequences. One such safe harbor is the adeno-associated virus integration site 1 (AAVS1) locus. In order to insert a functional copy of the PID-causing gene into a specific locus, such as AAVS1, one can use an engineered endonuclease to introduce a DSB at the site and a DNA repair template containing the gene flanked by two homology arms that match the AAVS1 sequence (36–39).

Bottom Line: With this treatment, severe complications may result due to integration within oncogenes.With these genome-editing tools a correct copy can be inserted in a precisely targeted "safe harbor." They can also be used to correct pathogenic mutations in situ and to develop cellular or animal models needed to study the pathogenic effects of specific genetic defects found in immunodeficient patients.This review discusses the advantages and disadvantages of these endonucleases in gene correction and modeling with an emphasis on CRISPR/Cas9, which offers the most promise due to its efficacy and versatility.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, Boston Children's Hospital, Harvard Medical School , Boston, MA , USA ; Department of Pediatric Immunology, Wilhelmina Children's Hospital, University Medical Center Utrecht , Utrecht , Netherlands.

ABSTRACT
Severe combined immunodeficiency (SCID) and other severe non-SCID primary immunodeficiencies (non-SCID PID) can be treated by allogeneic hematopoietic stem cell (HSC) transplantation, but when histocompatibility leukocyte antigen-matched donors are lacking, this can be a high-risk procedure. Correcting the patient's own HSCs with gene therapy offers an attractive alternative. Gene therapies currently being used in clinical settings insert a functional copy of the entire gene by means of a viral vector. With this treatment, severe complications may result due to integration within oncogenes. A promising alternative is the use of endonucleases such as ZFNs, TALENs, and CRISPR/Cas9 to introduce a double-stranded break in the DNA and thus induce homology-directed repair. With these genome-editing tools a correct copy can be inserted in a precisely targeted "safe harbor." They can also be used to correct pathogenic mutations in situ and to develop cellular or animal models needed to study the pathogenic effects of specific genetic defects found in immunodeficient patients. This review discusses the advantages and disadvantages of these endonucleases in gene correction and modeling with an emphasis on CRISPR/Cas9, which offers the most promise due to its efficacy and versatility.

No MeSH data available.


Related in: MedlinePlus