Use of Replicators in Gene Therapy

Gene therapies offer promising prospects of treating a wide variety of human diseases. In one method, a gene therapy vector can be utilized to deliver an unmutated copy of a gene, called a transgene, to replace a mutated gene in order to treat the genetic disorder. However, lack of expression of a therapeutic transgene and uncontrolled gene silencing are still major obstacles for safety and efficacy of these gene therapy interventions. There remains a need for a gene therapy vector that can deliver a stably maintained, appropriately regulated therapeutic transgene without adverse side effects.

Researchers at the National Cancer Institute (NCI) have shown that the inclusion of functional replicators, DNA sequences on chromatin that affect the sites of DNA replication initiation, can prevent gene silencing when incorporated into transgenes. The extent of transcriptional silencing of gene therapy vectors depends on their chromosomal location and on presence of nearby heterochromatin. Replicators interact with distal sequences to establish an epigenetic permissive state that directs the replication machinery to the replicator at a specific time during S phase. Most active genes replicate early during S phase, while transcriptional silencing correlates with late replication. NCI findings suggest that replicator sequences have an important role in stabilizing gene expression patterns, and the inclusion of replicators may be crucial in the prevention of gene silencing and replication delay.

Protected claims for this invention are directed to specific constructs and methods of use to inhibit, delay or prevent gene silencing. This technology thus enables the inclusion of functional elements in gene delivery vectors that permit stable maintenance and long-term regulated transgene expression, which may be key in the development of effective gene delivery vectors. This technology is available for licensing.